DEPARTMENT OF- THE

BULLETIN

UNITED STATES

GEOLOGICAL SURVEY

No. 86

CORRELATION PAPERS ARCHE AN AND ALGONKIAN.

WASHINGTON 

'GOVERNMENT PRINTING "OFFICE 

' 1892 ' " '

LIBRARY CATALOGUE SLIPS.

United States. Department of the interior. (U. S. geological survey). 

Department of the interior | |, Bulletin | of the | United 

States | geological survey | no. 86 | [Seal of the department] | 

Washington | government printing office | 1892

Second title: United States geological survey | J. W. Powell, 

director | | Correlation papers | Archeaii and Algoukiau | hy | 

Charles Richard Van Hise | [Vignette] |

Washington | government printing office | 1892

8°. 549pp. 12 pi.

Van Hise (Charles Eichard).

United States geological survey | J. W. Powell, director | | 

Correlation papers' | Archean and Algonkian | by | Charles liichard Van Hise | [Vignette] |

Washington | government printing office | 1892

8°. 549 pp. 12 pi.

[UNITED STATES. Department of the interior. (U. M. geological survey).' 

bulletin 86.]

United States geological survey | J. W. Powoll, director | | 

Con-elation papers | Archean and Algouluan | hy | Charles Kichard Van Hise | [Vignette] |

Washington | government printing office | 1892

8°. 549 pp. 12 pi.

[UNITED STATES. Department of the interior. (U. S. geological survey). 

Bulletin 86.]

G 2320
[Bulletin No. 86.]

The publications of the United States Geological Survey are issued in accordance with the statute 

approved March 3, 1879, which declares that 

"The publications of the Geological Survey shall consist of the annual report of operations, geological 

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.. Tenth Annual Report of the United States Geological Survey, 1888-'89, by J. W. Powell. 1890. 

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77. The Texan Permian and its Mesozoic Types of Fossils, by Charles A. White. 1891. 8°. 51 pp, 

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79. A Late Volcanic Eruption in Northern California aud its Peculiar Lava, by J. S. Diller. 1891. 8°. 

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80. Correlation papers Devonian and Carboniferous, by Henry Shaler Williams. 1891. 8°. 279pp. 

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81. Correlation papers Cambrian, by Charles Doolittle Walcott. 1831. 8°. 447 pp. 3 pi. Price 

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ADVERTISEMENT. V

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85. Correlation papers The Newark System, by Israel Cook Russell. 1892. 8°. 344 pp. 13 pi. 

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86. Correlation papers Archean and Algonkian, by C. R. Van Hise. 1892. 8°. 549 pp. 12 pi. 

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90. A report of work done in the Division of Chemistry and. Physics, mainly during the fiscal year 

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91. Eecord of North American Geology for 1890, by Nelson Horatio Darton. 1891. 8°. 88 pp. Price 

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92. The Compressibility of Liquids, by Carl Barns. 1892. 80 . 96pp. 29 pi. Price. 10 cents.

93. Some insects of special interest from Florissant, Colorado, and other points in tho Tertiaries of 

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95. Earthquakes in California in 1890 and 1891, by Edward Singleton Holclen. 1892. 8°. 31 pp. 

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96. The Volume Thermodynamics of Liquids, by Carl Barus. 1892. 8°. 100pp. Price 10 cents.

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97. The Mesozoic Echinodermata of the United States, by W. B. Clark.

98. Carboniferous Flora Outlying Coal Basins of Southwestern Missouri, by David White.

99. Kecord of North American Geology for 1891, by Nelson Horatio Darton.

100. Bibliography and Index of the publications of the U. S. Geological Survey, 1879-1892, by P. C. 

'Warm an.

101. Insect fauna of the Rhode Island Coal Field, by Samuel Hubbard Scudder.

102. A Catalogue and Bibliography of North American Mesozoic Invertebrata, by C. B. Boyle.

103. High Temperature Work in Igneous Fusion and Ebullition, Chiefly in Eolation to Pressure, by 

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104. Glaciation of the Tellowstone Valley north of the Park, by W. H. Weed.

105. The Laramie and the overlying Livingstone Formation in Montana, by W. H. "Weed, with 

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106. The Colorado Formation and'its Invertebrate Fauna, by T. W. Stanton.

107. The Trap Dikes of Lake Champlain Valley and the Eastern Adirondack's, by J. F. Kemp. 

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 Correlation papers Pleistocene, by T. C. Chamberlin.

 The Eruptive and Sedimentary Rocks on Pigeon Point, Minnesota, and their contact phenomena, by W. S. Bayloy.

 The Moraines of the Missouri Coteau, and their attendant deposits, by James Edward Todd.

 The Paleozoic Section in the vicinity of Three Forks, Montana, by A. C. Peale.'

 A Bibliography of Palcobotany, by David White.

STATISTICAL PAPERS.

Mineral Resources of the United States, 1882, by Albert Williams, jr. 1883. 8°. xvii, 813 pp. Price 

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Mineral Resources of the United States, 1883 and 1884, by Albert Williams, jr. 1885. 8°. xiv, 1016 

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Mineral Resources of the United States, 1885. Division of Mining Statistics and Technology. 1886. 

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Mineral Resources of the United States, 1886, by David T. Day. 1887. 8°. viii, 813pp. Price 50 cents.

MineralResources of the United States, 1887, by David T. Day. 1888. 8°. vii, 832 pp. Price 50 cents.

Mineral Resources of the United States, 1888, by David T. Day. 1890. 8°. vii, 652pp. Price 50 cents.

Mineral Resources of the United States, 1889 and 1890, by David T. Day. 1892. 8°. viii, 671 pp. 

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In preparation:

MineralResources of the United States, 1891.

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Survey should be addressed

TO THE DI HECTOR OF THE

UNITED STATES GEOLOGICAL SURVEY,

WASHINGTON, D. C.

WASHINGTON, D. C., December, 1893.
DEPARTMENT OP THE ISTBEIOE

BULLETIN

OF THE

UNITED STATES

GEOLOGICAL SURVEY

No. 86

WASHINGTON

GOVERNMENT PRINTING OFFICE 

1892

UNITED STATES GEOLOGICAL SURVEY

J. W. POWELL, DIRECTOR

CORRELATION PAPERS

ARCHEAI AND ALGOIKIAI

BT

CHARLES RICHARD VAN HISE

WASHINGTON

GOVERNMENT PRINTING OFFICE 

1892
, 8C,
CONTENTS.

PageLetter of transmittal ....................................................... 11

Outline of this paper........................................................ 13

Preface..................................................................... 15

Introduction................................................................ 19

Chapter I. The Original Laurentian and Huronian areas.................... 23

Section I. Eastern Ontario and western Quebec ........................ 23

Literature.......................................................... 23

Summary of results ................................................. 32

Section II. From north channel of lake Huron to lake Teniiscamang .... 35

Literature.......................................................... 35

Summary of results................................................. 46

Notes............................................................... 48

Chapter II. Lake Superior region........................................... 51

Section I. Work of the official geologists of the Canadian Survey and

associates............................................................. 51

Section II. Work of the early United States geologists and associates ... 72

Section III. Work of the Michigan geologists and associates............ 88

Section IV. Work of the Wisconsin geologists and associates ........... 105

Section V. Work of the Minnesota geologists and associates ............ 119

Section VI. Work of the later United States geologists and associates... 134

Section VII. Summary of results....................................... 156

Lake Superior sandstone ............................................ 157

The character of the Keweenaw series ............................... 160

Relations of Keweenaw and underlying series ...................... 161

General succession according to different writers .................... 162

Lithological characters of Azoic, Laurentian, Huronian, etc ......... 167

Origin of the iron ores .............................................. 170

The basic eruptives and stratigraphy................................ 173

Unconformity at base of clastic series............................... 174

Unconformity within clastic series .................................. 179

Correlation; general considerations ................................. 183

Equivalents of the Original Huronian series......................... 184

Equivalents of the Sioux quarfczites, St. Lojris slates, etc............. 186

Succession and equivalents of the Ponokee and Animikie districts

series............................................................. 187

Succession and equivalents of the Marquette district series .......... 189

Succession and equivalents of the Menoniinee and Felch mountain

districts series .................................................... 190

Equivalents of the Black river falls series............................ 190

Succession and equivalents of western Ontario and northeastern Minnesota series ........................................................ 190

Nomenclature........................................................ 391

Lake Superior basin ................................................ 196

Conclusion.......................................................... 196

Notes............................................................... 199

6
6 CONTENTS.

	Page. 

Chapter III. The Great Northern area ..............................i....... 209

Section I. The region ahout Hudson Lay............................... 209

Literature.......................................................... 209

Summary of results ................................................. 212

Section II. - Northern Canada........................................... 213

Literature.......................................................... 213

Summary of results from Dawsoii................................... 217

Section III. The lower St. Lawrence river and westward to lakes St.

John and MisstassinI.................................................. 218

Literature.......................................................... 218

Summary of results ................................................. 220

Notes............................................................... 220

Chapter IV. Eastern Canada and NeAvfouudland.... ,. ...................... 223

Section I. The Eastern townships ...................................... 223

Literature.......................................................... 223

Summary of results................................................. 226

Section II. Gaspe" peninsula............................................ 227

Literature .... t ....................................................^ 227

Section III. Central New Brunswick ................................... 227

Literature.......................................................... 227

Summary of results................................................. 229

Section IV. Southern New Brunswick .................................. 230

Literature.......................................................... 230

Summary of results................................................. 236

Section V. Nova Scotia and Ca,pe Breton ................................ 239

Literature .......................................................... 239

Summary of results ................................................. 244

Section VI. Newfoundland............................................. 247

Literature.......................................................... 247

. Summary of results .................................................. 251

Notes............................................................... 252

Chapter V. Isolated areas of the Mississippi valley......................... 257

Section!. The Black liills.'............................................. 257

Literature .......................................................... .257

. Summary of results ................................................. 260

Section II. Missouri.................................................... 261

. Literature .......................................................... 261

Summary of results .................................................. 265

Section III. Texas ..................................................... 266

. Literature .......................................................... 266

Summary of results ................................................. 269

"Notes............................................................... 270

Chapter VI. The Cordilleras................................................ 272

Section I. Laramie, Mediciue Bow, and Park ranges in southern Wyomin g. 272

. Literature .......................................................... 272

Summary of results ................................................. 276

Section II. Central and western Wyoming ............................. 277

. Literature of the Big Horn mountains............................... 277

Literature of the Rattlesnake mountains ............................ 278

Literature of the Sweetwater and adjacent mountains ............... 278

Literature of the Wind river mountains ............................. 279

Literature of the Gros Ventre and Wyoming ranges.................. 280

Literature of the Teton range....................................... 281

Summary of results ............... ................................ 281
CONTENTS.

Chapter VI. Continued.

Section ill. Central uud southwestern Montana, with adjacent parts ol'

Wyoming and Idaho .............................................. 282

Literature.. ......................................................... 282

Summary of results ................................................. 286

Section IV. Utah and southeastern Nevada ............................ 286

Literature of the Uiuta mountains .................................. 286

Literature of the Wasatch mountains................................ 289

Literature of the Promontory ridge, Fremont island and Antelope

island ranges ..................................................... 295

Literature of the Oquirrh mountains ............................. ^.. 295

Literature of the Aqui mountains ................................... 296

Literature of the Raft riv.er range .................................. 296

Literature of southern Utah and southeastern Nevada ............... 296

Summary of results ................................................. 297

Section V. Nevada, north of parallel 39° 30' ............................ 299

Literature........................................................... 299

Summary of results ................................................. 306

Section VI. Colorado and northern New Mexico ........................ 308

Literature of the Front range, north and east of the Arkansas........ 308

Literature of the Wet and Sangre de Cristo mountains............... 313

Literature of the Front range of southern Colorado and northern New

Mexico ........................................................... 314

Literature of the Park range ........................................ 316

Literature of the Sawatch mountains................................ 316

Literature of the Elk mountains...................................... 317

Literature of the Grand and Gunuison rivers ........................ 318

Literature of the Quartzite mountains .............................. 319

Literature of the La Plata mountains ............................... 323

Summary of results ................................................. 324

Section VII. Arizona and western New Mexico.......................... 326

Literature.......................................................... 326

Summary of results ................................................. 330

Section VIII. California, Washington, and British Columbia............ 332

Literature of California, with adjacent parts of Nevada and Arizona. 332

Literature of Washington........................................... 337

Literature of British Columbia...................................... 337

Summary of results ................................................. 341

Notes............................................................... 342

Chapter VII. Eastern United States........................................ 348

Section I. The New England States .................................... .348

Literature of Maine................................................. 348

Literature of New Hampshire ....................................... 350

Literature of Vermont ................................".............. 355

Literature of Massachusetts......................................... 361

Literature of Rhode Island...........................,.............. 377

Literature of Connecticut........................................... 377

General literature................................................... 379

Summary of results ................................1................ 382

Section II. The Middle Atlantic States .................:............... 386

Literature of New York............................................. 386

Literature of New Jersey ........................................... 399

Literature of Pennsylvan ia ......................................... 404

Literature of Maryland.............................................. 410

Literature of Delaware.................I............................. 412

General literature................................................... 413

Summary of results.................................................. 413
8 CONTENTS.

Chapter VII. Continued. Page.

Section III. The Southern Atlantic States .............................. 416

Literature of the AHrginias.......................................... 416

Li terature of North Carolina........................................ 418

Literature of Tennessee ............................................ 422

Literature of South Carolina ........................................ 423

Literature of Georgia ............................................... 425

Literature of Alabama .............................................. 426

General literature................................................... 427

Summary of results ................................................. 427

Notes ........................ ...................................... 429

Chapter VIII. General successions and discussions of principles ............. 440

Section I. Literature................................................... 440

Section II. General disciission.......................................... 470

Names applied to pre-Cambrian rocks ............................... 470

The character of the Archean........................................ 475

 Origin of the Archean............................................... 478

Delimitations of Archean............................................ 484

Stratigraphy of Archean ............................................ 487

Necessity for a group between Cambrian and Archean ............... 491

Delimitations of "the Algonkian...................................... 493

Difficulties in Algonkiau stratigraphy ............................... 496

The Original Laurentian and associated areas ....................... 497

The Original Hurouian.............................................. 498

Lake Superior region ............................................... 499

The region about.Hudson bay....................................... 500

Other regions of Northern Canada ................................... 501

The Eastern Townships ............................................. 501

Southern New Brunswick ........................................... 502

Nova Scotia and Cape Breton........................................ 502

Newfoundland...................................................... 503

The Black hills..................................................... 503

Missouri............................................................ 504

Texas............................................................... 504

Medicine bow range ................................................ 504

Southwestern Montana.............................................. 504

The Uinta mountains ............................................... 505

The Wasatch mountains ............................................. 505

Promontory ridge, Antelope and Freinont islands.................... 506

The Aqui mountains ................................................ 506

Scaell creek, Egan, Pogonip or AVhite Pine, and Piiiou ranges........ 506

Front range of Colorado ............................................ 506

The Quartzite mountains............................................ 507

Grand Canyon of the Colorado ...................................... 507

British Columbia.................................................... 507

The Adirondacks.................................................... 508

Other Algonkian areas .............................................. 508

Subdivisions of Algonkiau .......................................... 509

Comparison with other classifications................................ 509

Principles applicable to Algonkian stratigraphy ..................... 511

Results in America and Europe compared............................ 524

Notes............................................................... 527

Index................................................................ 531
ILLUSTRATIONS.

Page. 

Plate I. Geological map of a portion of southern Canada...... 1................ 24

II. Geological map of the Original Hnroniaii rocks....................... 34

III. Geological map of the lake Superior region........................... 52

IV. Geological map of northern Canada A................................ 210

V. Geological map of New Brunswick, Nova Scotia, and part of Qnehec.. 224

VI. Geological map of Newfoundland .................................... 248

VII. Geological map of portions of Montana, Idaho, Wyoming, and Dakota. 258

VIII. Geological map of Utah and Nevada.................................. 286

I.. Geological map of portions of Colorado and New Mexico.............. 308

X. Geological map of Arizona and part of New Mexi co................... 326

XI. Geological map of the northeastern states............................ 348

XII. Geological map of the southeastern states............................ 416

9

LETTER OF TR ANSMITTAL.

DEPARTMENT OF THE INTERIOR,

U. S. GEOLOGICAL SURVEY, 

DIVISION OF GEOLOGIC CORRELATION,

Washington, I). C1 ., January 30,

SIR : I have the honor to transmit herewith a memoir by Prof. 0. E. 

Van Hise on the Archeau and Algonkian of North America, prepared 

for publication as a bulletin.

The Division of Geologic Correlation was created for the purpose of 

summarizing existing knowledge with reference to the geologic formations of North America, and especially of the United States 5 of discussing the correlation of formations found in different parts of the 

country with one another and with formations in other countries 5 and 

of discussing the principles of geologic correlation in the light of American phenomena. The formations of each geologic period were assigned 

to some student already well acquainted with them, and it was arranged that he should expand his knowledge by study of the literature 

and by field examination of classic localities, and embody his results in 

an essay. The general plan of the work has been set forth on page 16 

of the Ninth Annual Eeport of the Survey, and on pages 108 to 113 of 

the Tenth Annual Eeport, as well as in a letter of trausmittal of Bulletin No. 80.

The present essay is the seventh of the series, having been preceded 

by essays on the Carboniferous and Devonian, the Cambrian, the Cretaceous, the Eocene, the Neocene, and the Newark systems; prepared 

severally by Messrs. Williams, Walcott, White, Clark, Dall and Harris, 

and Eussell, and constituting Bulletins 80, 81, 82, 83, 84, and 85.

The voluminous literature of the pre-Cambrian rocks of North America is abstracted in a thorough manner, being classified for this purpose 

primarily by geographic districts and secondarily by dates. The division of the rocks into two great classes, the Archean and Algonkian, 

taxonomically coordinate with the periods under which the fossiliferous clastic rocks are classified, is then advocated and set forth at 

length. As these rocks do not contain faunas available for purposes of 

correlation, their classification, both major and minor, is necessarily

11
12 LETTEE OF TRANSMITTAL.

based on physical characters and relations, and much attention is 

therefore given to the discussion of the possibilities and limitations of 

correlation by means of physical data. It is concluded that with present information the correlation of pre-Cambrian series and formations 

of different geologic provinces is impracticable. 

Very respectfully, your obedient servant,

G. K. GlLBEET,

Geologist in charge. 

Hon. J. W. POWELL,

Director U. S. Geological Survey.
OUTLINE OF THIS PAPER.

This hook is a review of the present state of knowledge of the general structure of 

the pre-Cambrian rocks of the United States and Canada. The material contained 

in the historical chapters is of two kinds: Summaries of all articles pertaining to the 

suhject considered, and summaries of the con elusions which appear to be established. 

The first represents the substance of the literature; the second brings together the 

important ascertained structural facts, and oftentimes becomes a more or less extended 

discussion. The final chapter covers the same grounds as the historical chapters for 

the various pre-Cambrian general successions proposed by different authors, and also 

contains a discussion of results and the principles upon Avhich they are based. Within 

the chapters, individual districts or regions are given separate sections, and the summary of literature for each is arranged in chronological order. As used in tins volume, the term Cambrian is defined as delimited below by the base of the Olenelliis 

fauna; Algonkian includes the pre-Olenellus elastics and their equivalent crystallines; while the Archean includes the completely crystalline rocks below the Algonkian.

The several chapters have the following scopes: Chapter I: The Original Laurentian and Huronian areas treats of eastern Ontario and western Quebec, and the area 

from the north channel of lake Huron to lake Temiscarnang. Chapter II: Lake 

Superior Region summarizes the work of the official geologists of the Canadian 

Survey and associates, of the early United States geologists and associates, of the 

Michigan geologists and associates, of the Wisconsin geologists and associates, of 

the Minnesota geologists and associates, of the later United States geologists and 

associates, and gives a summary and discussion of results. Chapter III: The Great 

Northern Area treats of the region about Hudson bay, northern Canada, and the 

lower St. Lawrence river region. Chapter IV: Eastern Canada and Newfoundland 

treats of the Eastern townships, Gasp6 peninsula, central New Brunswick, southern 

New Brunswick, Nova Scotia and cape Breton, and Newfoundland. Chapter V: 

Isolated Areas of Dakota, Missouri and Texas treats of the Black hills, the preCambrian of Missouri, and the central Mineral region of Texas. Chapter VI: The 

Cordilleras treats of 'the many mountain ranges in the far west. Chapter VII: 

Eastern United States" treats of the New England, Middle Atlantic, and Southern 

Atlantic states. Chapter VIII: General Successions and Discussions of Principlessummarizes the various general successions proposed, suggests one, and discusses the 

principles of pre-Carabrian stratigraphy.

The more important conclusions of this chapter are as follows: The Archean is the 

basal complex of America. It has everywhere, if large areas are considered, an 

essential likeness. It consists mainly of granitic, gneissic and schistic rocks, among 

which are never found beds of quartzite, limestone, or any other indubitable elastics. 

One kind of rock may occupy considerable areas, but when different kinds are associated their structural relations are most intricate. These relations, as well as the 

completely crystalline schistose character of the rocks, the frequent broken and distorted forms of the mineral constituents, and their involuted foldings, are evidence 

that these most ancient rocks have passed through repeated powerful dynamic movements.

As to the origin of the Archean rocks, three different views are proposed: (1) They 

may be considered as metamorphosed detrital rocks. (2) They may be considered as 

igneous and later in origin than certain of the pre-Cambrian elastics. (3) They may 

be considered as igneous and representing either a part of the earth's original crust 

or else originally crystallized material which has now reached the surface as a conse13
14 OUTLINE OP THIS PAPER,

quence of inward crystallization and subsequent deep denudation. The Archean 

rocks have no limit below, but are limited above by the Algonkian. While structural 

methods have been applied to the Archean rocks, they have not thus far been successful, and the only subdivisions which are at present applicable are those of a 

lithological character.

In various parts of North America are one or more series of clastic rocks between 

the Archean and Cambrian. These occur in the Original Lanrentian area, the Original Hurouian area, in the lake Superior region, in the region about Hudson bay, in 

the Eastern townships, in southern New Brunswick, in Nova Scotia and cape Bret6n, 

in Newfoundland, in the Black hills, in Missouri, in Texas, in many ranges of the 

Cordilleras, in the Grand canyon of the Colorado, in British Columbia, in the Adiroudacks, and in other areas. Within these rocks, in many localities, are evidences 

of abundant life, and in a few "places are definitely recognized fossils. The U. S. 

Geological Survey, recognizing that it is too early to classify the great thicknesses 

of rocks between the Archean and the Cambrian in North America into systems coordinate in value with those of the subdivisions of the Paleozoic, has proposed the 

term Algoukian for the whole. The Algonkiau system is then delimited below by 

the Archean and above by the Cambrian.

In many regions it is easy to differentiate the Algonkiau from other rocks. This 

is especially true where they are separated from them by unconformities. In other 

regions it is difficult to separate them from the Archean and Cambrian rocks, as 

there sometimes appear to be gradations between them. In this respect the Algonkiau system is in no way different from others.

Algonkian stratigraphy is more difficult than post-Algonkian stratigraphy; because the further back we go in the history of the world for any given region the 

more numerous and frequent have been the changes through which any given rock 

stratum has passed; and because as yet fossils have not been found in sufficient 

quantity to be of any assistance in 'stratigraphy. However, in many regions it has 

been possible to subdivide the Algonkiau rocks into series and these series into formations. In different regions these formations and series differ widely in the degree 

of crystallization, in their lithological character, and in their order of succession. 

In this respect Algonkian rocks are not different from those of post-Algonkian age. 

Considering the continent as a whole, age is no guide to the chemical or mineral composition, texture, color, degree of crystallization, or any other property of a formation, or vice versa, although in a given district or region any one of them may become important guides in stratigraphy.

In certain regions it has been fonnd possible to correlate series with a great degree of probability and in some cases formations which occur in different districts. 

In regions separated from each other by great distances, and which therefore may 

have had different physical conditions at the same period, it is not yet possible to 

make safe correlations of sxibdivisions of the Algonkian of America. If this conclusion be correct, it is evident that the application of such American terms as 

Keweenawan, Hnronian, etc., to European rocks is not warranted. In working out 

the geology of a region, local names should be applied to formations and scries. 

Later, with fuller knowledge, these may perhaps be correlated with series to which 

classical names have been applied.

Physical methods of correlation being the only ones at present available, it becomes 

necessary to closely scrutinize these methods, estimate their relative value, and point 

out the services that each may be expected to perform. Of these methods unconformity must be given the foremost place for major divisions within a region. 

Unconformity may be established by any one of the following phenomena, or by a 

combination of two or more of them: (1) Ordinary discordance of bedding; (2) differ, 

ence in the number of dynamic movements to which the series have been subjected; 

(3) discordance of bedding of upper series and foliation of lower; (4) relations with 

eruptives; (5) difference in degree of crystallization; (6) basal conglomerates; (7) 

general field relations.
PREFACE.

In the preparation of this book great difficulty has been encountered 

beowuse of the unequal value of statements of fact by different men. 

Oftentimes in regions with which the writer is not familiar it is impossible 

to discriminate surely between good and poor work. In certain cases 

in which reports have read plausibly, an examination of the purported 

facts in the field with the accounts in hand has shown the descriptive 

parts to be so inaccurate as to render the conclusions, while apparently 

well founded, wholly valueless. But in general, when an author of this 

class has written much, discrepancies between the statements of facts 

appear.

Those who change their opinions are of different classes. A man who 

progresses must change his views, but the descriptive parts, given 

while an old view was held, ought to be still more useful for support of 

the new position. The old view may have contained a large element of 

truth, and is perhaps included in the newer, larger position. In reports 

the part that purports to be facts should be wholly separable from 

the general theories held, just as detailed maps, if rightly constructed, 

indicate the observations made and the generalizations drawn. More 

frequently than not, facts and theories are so inextricably mingled 

that no independent judgment can be reached as to the correctness 

of the conclusions, and often the facts of a report can not be used even 

by one personally familiar with the districts of which the report treats. 

The conclusions of another class of geologists are .a series of guesses, 

which generally serve no purpose except that when any one of the 

numerous guesses has been established by the patient work of an investigator, the conclusion is at once claimed as a prior discovery of the 

guesser. Sometimes the discoveries announced by a writer almost or 

quite simultaneously, are wholly inconsistent with one another and 

with the facts which are described; for as with other men, so with 

geologists, many opinions are held at the same time which logically 

are exclusive of one another. Still another group of writers early 

reach a general theory as to the definite order of the evolution of the 

world. A person of this group year after year repeats the old statements and conclusions without any reference to the establishment of 

their falsity. More often than not, he is one who has done little or 

no systematic detailed field work in any region. All facts and conclusions which bear in his direction are hailed as discoveries; " all is grist

15
16 PREFACE.

which comes to his mill; ".while every adverse fact or conclusion is explained out of existence or dismissed as unworthy of consideration.

By following continuously the summaries of the writings of a geologist who has been long at work in.a region it will generally not be difficult to get a fairly accurate idea of the value of the work done.

During the preparation of this review, I have visited many districts 

of North America, but I have not been able to see important districts 

which I hoped to study before the submission of this volume. With 

the United States side of the lake Superior country I am tolerably 

familiar, having for a number of years given nearly the full field seasons 

to work in various parts of this region. Besides doing general work, 

I have mapped in detail certain districts. From time to time various 

parts of the Canadian lake Superior region have been visited. While 

no systematic mapping work has been done in regions other than that 

of lake Superior, reconnaissances and occasional detailed sections have 

been made in many. In the far West these include the Black hills of 

Dakota, southwestern Montana, the Laramie and Medicine Bow mountains of Wyoming; theTJinta and Wasatch mountains of Utah; and the 

Quartzite mountains arid Front range of Colorado, In the Mississippi 

valley the crystalline region of Missouri has been seen. In company 

with Eaphael Pumpelly, Bailey WiMis, J; A. Holmes, 0.D. Walcott, G. H. 

Williams, E. W. Ells, or alone, more or less extended trips have been 

made in Georgia, east Tennessee, North Carolina, eastern Maryland, eastern Pennsylvania, northern New Jersey, southern New York, the Berkshire hills, Green mountains, Adirondacks, Hastings district of Ontario, 

and the area of the Grenville series constituting the Original Laurentian. 

For the most part this work has not been of such a detailed nature as 

to add greatly to previous knowledge of these regions. The aim has 

been rather to get such a familiarity with them as would enable the 

writer to judge accurately of the results already reached. This statement does not apply to a part of the Adirondacks, where a somewhat 

closer study was made; also, in North Carolina a nearly complete section was made from the eastern side of the Piedmont plain through the 

Blue ridge to the uncrystalline rocks of east Tennessee. The Original 

Huronian area has been seen at three different times. The first time, 

in company with the late Dr. E. D. living, the North channel was 

coasted in a small boat and the interior visited, so that all of Logan's 

members of this series were seen, as well as the underlying Laurentian. 

In a second trip, also in company with Prof. Irving, the Canadian Pacific railroad was traversed twice on a hand car from Algoma Mills to 

Sudbury, a distance of 100 miles. The third trip, with Prof. Eaphael 

Pumpelly, was again along the North channel of lake Huron, the object 

of special study being the possible existence of two series within the 

Huronian3 and the structural relations between the lowest Huronian 

and the Laurentian.
PREFACE. 17

The labor involved in abstracting the pre-Cambrian literature of 

North America has been great. This is shown by the large number of 

books and articles actually summarized. These, however, give an imperfect idea of the volume of literature covered; for very numerous 

articles have been examined which repeat what had already been summarized from other papers. Also a vast a'mount of material from which 

nothing is taken has been looked through, in order to ascertain whether 

it contained anything Avhich ought to be considered. In all cases 

summaries are made from the original articles, with the exception of 

a part of the section upon northern Canada. Nearly the entire literature of the geology of this region has recently been clearly compiled by 

Dr. George M. Bawsou, and from this compilation the major part of the 

summary for this region is taken.

To a card catalogue of the Appalachians by 1ST. H. Barton, to Azoic 

Eocks and other works by Hunt, to the Minnesota reports, to the Azoic 

System by Whitney and Wadsworth, to Irving's Copper-bearing Bocks, 

and also to many other works the writer is much indebted as furnishing 

guides to the pre-Cambrian literature. In this way Barton's catalogue 

and the Azoic System have been by for the most valuable. After independently preparing abstracts of papers and reports I have compared 

them with the abstracts contained in the Azoic System in order to discover omissions, and this book has thus enabled me to make the survey of literature more nearly complete than it otherwise would have 

been. To a certain extent other books have been used in the same 

fashion.

Mr. W. N. Merriarn has dniAvn all the maps for the illustration of the 

volume. To Mr. George E. Luther the writer is indebted for most efficient clerical assistance from the outset, without which it would have 

been impossible to complete this volume within the time allotted.

To Sir Archibald Geikie, Br. Hans Keusch, Br. K. A. Losseii, MichelLevy, and Br. Johannes Lehniann I am indebted for summary statements 

of the condition of knowledge with reference to the pre-Cambrian of 

Groat Britain, France, Germany and Scandinavia.

With Messrs. 0. B. Walcott, G. fl. Williams, Bailey Willis, and E. W. 

Ells I have been in the field and in consultation, and from them have 

received much useful information.

Mr. G. K. Gilbert has kindly read the manuscript, and has made many 

suggestions which have been of value.

To the late Prof. Eoland B. Irving, and to Prof. Eaphael Pumpelly I 

am indebted in a peculiar manner. With the former 1 was associated 

in Avork from my earliest studies in geology until Ms death. With 

the latter I have been much in the field for the last two seasons and 

have received many pregnant ideas. What part of the thoughts contained come from these two friends I am unable to specify in detail, but 

I am conscious that the debt is a heavy one. 

Bull. 86 2
18 PREFACE.

No one else will feel so keenly the imperfections of this volume as the 

writer. Papers will be found to be overlooked of which sumin aries ought 

to have been made. Mistakes of interpretation will be found. Undue 

proportion in the summaries will be discovered. I can only say that 

I have attempted to reduce these defects to a minimum. It will be 

esteemed a great favor, with reference to a possible future edition, if 

all who discover such omissions and mistakes will communicate them 

to the writer.

C. E. V.

MADISON, Wis., July, 31,1801.
A REVIEW OF THE PRESENT STATE OF KNOWLEDGE 

OF THE PRE-CAMBRIAN ROCKS OF NORTH AMERICA,

BY 0. B. VAN HISE.

INTRODUCTION.

The purpose of this book is to give an account of the present state of 

knowledge of the general structure of the pre-Cainbrian of the United 

States and Canada. It is not a bibliography of pre-Cambrian literature, nor a petrography of the pre-Cambrian rocks, nor a treatment of 

metamorphism, nor an account of economic facts. Mere occurrences of 

pre-Cambrian or crystalline rocks are not referred to unless the districts 

are new. Petrography, metamorphism, and economic geology are considered only so far as they have a direct bearing upon structural results, and then the substance of the established conclusions is given 

rather than the facts upon which they are based and the manner of 

reaching them.

The material contained in the historical chapters of this volume is of 

two kinds: First, a summary of all articles or parts of articles which 

have contributed knowledge upon the subject considered; and second, 

summaries of the conclusions which appear to be established in the 

various regions, while the final chapter covers the same ground for 

general successions proposed and also a discussion of these results and 

the principles upon which they are based. °No summaries are made of 

writings based wholly upon the field work and reports of others. This 

report is not a review of reviews; neither is purely controversial literature noticed. When a paper is made up in part of an original investigation and of a discussion of the works of others, only the first part is 

summarized. When the same writer repeats the same facts and conclusions several times, summary is made of the most comprehensive 

article and references are made to the others in the footnotes. 1 Oftentimes a final report includes all found in several annual reports. In 

this case the final report only is summarized. In making summaries 

the conclusions reached by the various authors are always given, and 

as full an account of the facts upon which they are based as is possible 

without extending this book beyond bounds.

'At the end of each chapter.

19
20 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BOLL. 86.

The abstracts given have the defects of all summaries a certain 

amount of inaccuracy, because all modifying and qualifying facts can 

not be given, and an undue amount of emphasis in the conclusions. In 

regions in which much work has been done these defects are not so 

serious as in little studied regions, for in the former the observations 

of independent observers confirm or neutralize each other.

So far as possible, in the summaries, the original language of the 

author is used, although a single sentence of the summary may be taken 

from several sentences of the original. Where the ideas can be conveyed in a briefer manner than in the original language other words 

are used. No quotations are made; for the ideas contained, whether 

in the original language or not, are wholly the ideas of the author the 

whole is in fact really quoted. It might be thought that better results 

would have been reached by indicating through quotations what words 

are taken from the original, but this method would have necessitated 

an unpleasant and constant alternation from quoted to nonquoted 

phrases. It would have made it much more difficult to convey briefly 

the thoughts of the original; for the words which are adapted to complete expositions are often not the best adapted to a resume. At first 

the plan of quoting was followed, but this was abandoned, because it 

was seen that carrying it out would add greatly to the size of this 

volunie without enhancing, if indeed it did not diminish, the accuracy 

and comprehensiveness of the review.

Due proportion should be maintained between the abstracts of the 

various writings. Frequently a short article contains much more of 

structural importance than one of far greater length, although the 

longer article may contain much of interest which does not come within 

the scope of the paper. Into the summaries the editor enters only in 

so far that he must of necessity take what appears to him important 

and omit what appears unimportant. Undoubtedly in this respect many 

mistakes are made; future investigations will show that omitted facts 

and conclusions have greater importance than now appears; but a perfectly proportioned summary.could be made only by perfect knowledge.

The necessarily brief summaries will perhaps serve the purposes of 

those who are interested in the general stratigraphy of the pre-Cambrian. 'They will not answer for those who wish to understand in 

detail the structure of any given region. For this local details are necessary. As the summaries are not made with reference to upholding 

any theory, they of necessity will fail to give all the facts which bear 

upon any particular hypothesis. But even for these special purposes 

it is hoped this volume may be found sufficiently full to be useful, and 

it certainly will assist in directing to the important literature.

In the discussion the aim has been, not to call attention to all that 

seems to be erroneous, but first to point out where there is harmony 

between the different authors, often veiled because terms are used 

with different significations; and, second, to note the important conclu-
VANHISB.] INTRODUCTION. 21

sions which have been clearly determined. Statements and conelusknis with which,, the writer does not agree are in general not criticised, nor is any refutation attempted, unless the point at issue is one of 

such a fundamental character that it can not be overlooked.

The maps are in all cases compiled from the original sources, and, like 

the summaries, have whatever excellence or defects the original work 

has. In many cases the editor feels assured that the maps will need to 

be materially modified, but he has not the detailed knowledge necessary 

to make the modifications. The generalized character of the boundaries is often indicated by the fact that they are straight lines. It need 

not be said that true geological boundaries are not of this nature in 

much disturbed regions. In the Appalachians the maps merely 

outline the crystalline rocks. Much of the area included is known to 

belong to the Paleozoic, but it is impossible either accurately to separate 

these areas or to subdivide the pre-Cambrian. All that can be done 

in many areas is to indicate that the rocks are pre-Cambrian, although 

it is oftentimes certain that Algonkian and Archean rocks both occur, 

which have not been separated in mapping. In a few regions, not only 

can the Archean and Algonkian be discriminated, but the latter has been 

subdivided into series and these into formations. There are then on 

the maps all grades of knowledge, from the eastern United States, 

where the pre-Cambrian is not outlined, to areas in which pre-Cambrian series are divided into formations. The maps, as the summaries, 

are a re'sume' of the present imperfect knowledge.

The order in which the districts are taken up is not consistently 

geographical or geological, but rather the order of the development 

of exact knowledge of the pre-Canibriau rocks. The great Canadian 

pre-Cambrian area in all its parts is a geological unit, yet the detailed study of it has been confined somewhat closely to particular 

regions5 and of necessity the regions which have been units of work 

have to be followed rather than a strictly logical order. Chapter I is 

devoted to the original Laurentian and originalHuronian areas. Chapter II is given to the lake Superior region. These regions are taken 

first because the exact knowledge of the pre-Cambrian rocks is here 

greater than in other ^areas. The Appalachian region, although the 

earliest to be studied, is reviewed last, for it is the area in which the 

conditions for obtaining exact knowledge are the least favorable, and 

about which comparatively little structural knowledge of the pre-Cambrian has been acquired.

In the summaries of the individual districts the order is that of appearance of the papers. By giving the entire summary of the literature 

of one district before taking up another, epitomes of parts of a single 

paper are necessarily dissociated. By this method something of correlation is lost; but purely general work is summarized in the general 

chapter and the subject of correlation is bere treated.
22 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL.86.

In regard to regions like the Appalachians and California, in which 

post-Cambrian rocks have become completely crystalline and liavebeeu 

for many years and are yet confused with pre-Cambrian rocks, summaries unavoidably extend beyond the proper scope of this paper. Of 

series which were in the past supposed to be pre Cambrian, but which 

have been demonstrated to be Cambrian or post-Cambrian, the fact 

is mentioned, but the literature which concerns them is not summarized, since it does not fall within the scope of this paper. The particular position which such formations shall take in Cambrian or postCambrian time is a subject for others^o consider.

Of necessity the eruptives which have not been differentiated from 

the pre-Cambrian have to be considered. Oftentimes it is quite probable that eruptives noted belong to post-Cambrian time. No paper is 

summarized bearing upon the unmistakable Cambrian or post-Cambrian eruptives unless it has a direct bearing upon the character or relations of the associated rocks of pre-Cambrian age.

All references to literature are given at the ends of the respective 

chapters, the reference notes haying continuous numbers. In the discussions closing sections or chapters and in the general chapter citations are not repeated. The original source of any statement attributed to an author may always be found by the aid of the index, where 

the name of each author is followed by references to the pages where 

his work is summarized.

The terms group, system, series, are used with the stratigraphical 

significance given them by the International Geological Congress. The 

corresponding chronological terms era and period are used. Formation is used as one of the members of a series, as quartzite formation 

or limestone formation of the Huronian series. The term " crystalline 

schist" is rigidly confined to rocks which have a " completely crystalline interlocked texture, which is possessed of a schistose parting due 

to a parallel or foliated arrangement of the mineral ingredients, or of 

aggregations of these ingredients." The finely banded gneisses are 

typical examples. All rock masses which within themselves show indubitable evidence of clastic origin are excluded from the crystalline schists and are regarded as semi or partially crystalline. A clastic 

or semi-crystalline formation may grade into a crystalline schist.

In the summaries of results and in the general discussion (Chapter VIII), unless otherwise stated, the term Cambrian is delimited below 

by the Olenellus fauna. The term Algonkian is a system term, covering 

all recognizable pre-Cambrian clastic rocks. The term Arch eon i,ia coordinate-system term, covering all pre-Algonkian rocks. It therefore 

includes only completely crystalline rocks, but does not include all rocks 

of this kind, as lioJocrystalline rocks of eruptive and sedimentary origin may occur in. Algonkian or post-Algonkian time. The propriety of 

these usages will appear in what follows.
OHAPTEE I.

THE ORIGINAL LAURENTIAN AND HURONIAN AREAS. 

SECTION I. EASTEEN ONTARIO AND WESTERN QUEBEC.

LITERATURE.

LOG-AN, 1 in 1847, describes between the Ottawa and Mattawa rivers, a 

metamorphic series of rocks, which, in its highly crystalline character, 

belongs to the order named by Lyell Primary. They are called metamorphlc, because their aspect is such as to lead to the theoretical belief that they may be ancient sedimentary formations. A red syenitic 

gneiss, in which hornblende and mica are arranged in a parallel direction, is the predominant rock. The thickness of the gneiss is not ascertained. South of the Mattawa and Ottawa are important beds of 

coarse crystalline limestone inter stratified with the gneiss in a conformable manner, although this conformity would not be seen in a small 

area, because of the minor complicated contortions. One section at 

High fallSj on the Madawaska., has a thickness of 1,351 feet3 and consists of gneiss, crystalline limestone, with a small amount of micaceous 

quartz rock, the gneiss greatly predominating. The areas which bear 

limestone are so distinct that they are placed as a separate group of 

metamorphic strata, supposed from their geographical position and general attitude to overlie the syenitic group conformably. Both of the 

metamorphic groups are frequently traversed by dikes and veins, including those of a granitic and pyroxenic character. From the vicinity of Quebec the limestone group ranged along the St. Lawrence, a distance varying from 10 to 20 miles, reaches the seigniory of Argenteuil, 

where it makes a turn toward the valley of the Ottawa, is seen above 

Grenville, and is last seen about half way between Fort William and 

Joachim falls, and at Portage de Talon, on the Mattawa. In the vicinity of Grenville the limestone is plumbaceous.

LoGAN,2 in 1852, finds a metamorphic and gneissic series of a widespread occurrence upon the river du Kord and the country to the westward. The Potsdam formation rests unconformably upon the inetamorphic series.

MURRAY,3 in 1852, describes a metamorphic series upon and north of 

the Upper St. Lawrence. On the Thousand isles are micaceous and 

hornblende gneisses. Crystalline limestones, quartzites, and conglommerates are all found upon the mainland, and the latter is cited as 

decisive evidence of the metamorphic character of the series as a whole.

'For notes see end of chapter, p. 48.

23
24 PRE-CAMBRIAN ROCKS OF NORTH AMERICA." [BCLT..W.

LoGAN,4 in 1854, applies to the series before called " metamorphic" 

underlying the fossiliferous formations of Canada the name Laurentian 

series, because metamorphic is applicable to any series of altered rocks. 

The proposed name is founded on that given by Mr. Garneau to the 

chain of hills which they compose. Above the Laurentian series is the 

Potsdam sandstone.

MURRAY,* in 1854, remarks that south of the Laurentian series are 

the more recent fossiliferous rocks. The Laurentian series consists of 

masses of micaceous and hornblende-gneiss and masses of interstratified crystalline limestone. Intrusive granite is found in the gneiss. 

Th.e magnesian crystalline limestone layers, one 700 feet thick, are persistent. A section of gneiss, mica-schist and quartzite, all sometimes 

garnetiferoiis, and two belts of limestone, together 140 feet thick, make 

up a succession 1,369 feet thick at Birch lake. In the series is a conglomerate, the matrix of which in one case is a limestone and the pebbles of quartz and feldspar. In another conglomerate are distinct pebbles in a talcose slaty matrix. These pebbles are sometimes distinctly 

rounded and flattened, the flat sides always lying parallel with the bedding. The pebbles vary from 5 or 6 inches in diameter to those so small 

as not to exceed the size of snipe shot.

LOG-AN,C in 1857, describes the Laurentian formation for some distance north of the Ottawa river between rivers Rouge and du Nord. 

The rocks are found to be limestone, gneiss, and quartzite. The limestone formations are used chiefly in working out the structure, but even 

with this guide, on account of the repetition of layers by folding and 

lack of fossils, the work is very difficult. All of the above rocks are 

taken to be metamorphosed sediments. They are cut by eruptives, such 

as syenite, porphyry, and greenstone, which are older than the fossiliferous formations.

MURRAY,7 in 1857, finds Laurentian rocks largely exposed between 

Georgian bay and the Ottawa river. The rocks are red and gray 

gneisses, micaceous and hornblendic schists, quartzite, and crystalline 

limestone. On lake Mpissing and its islands is found the Laurentian 

formation, consisting of gneiss, mica-schist, hornblende schist, crystalline limestone, and associated with this beds of specular ore. Limestones are also found along Muskoka river. The strata are everywhere 

more or less corrugated, in many places exhibiting sharp and complicated folding. They are intersected by quartzo-feldspathic and quartz 

veins. The Laurentian rocks of Georgian bay are separated from the 

Huronian north of lake Huron by a line running from the northwest 

side of Shibahahnahning to the junction of the Maskanongi and Sturgeon rivers, its course being in a northeasterly direction.

HUNT,8 in 1857, states that stratified feldspathicrocks are closely associated with the crystalline limestones, which alternate with gneissoid 

and quartzose rocks of the Laurentide mountains. These rocks, besides 

containing pyroxene,which passes over into hypersthene and a triclinic 

feldspar, contain as accidental minerals, mica, garnet, and iliuenite.
U.S.GEOLOGICAL SURVEY. B

UNCLASSIFIED PRE-CAMB. ALGONKIAN ALGONIKIAN! POST-ALGONKIAN ERUP.TIVES

GEOLOGICAL MAP OF A PORTION OF CANADA

SHOWING PRE-CAMBRIAN AND CRYSTALLINE ROCKS

Compiled from Official Maps of the Canadian Geol. Survey Scale - '----
EASTERN ONTARIO AND WESTERN QUEBEC. 25

Loc-fAN, 9 iii 1858, in describing the Laurentian of Ottawa thinks it probable that it can be divided into two great groups: that characterized 

by the presence of limestone and that without, and the latter of these 

groupsvalso will be capable of subdivision. Often interstratified with 

the limestones are bands of quartzite which are heaviest near the junction of. the limestone and the gneiss. The greatest mass of quartzite 

is beneath the limestone and is 400 feet thick. The limestones of 

the Laurentian are influenced in their strikes and dips by subsequent 

masses of igneous rocks. However, to these rocks as a whole, as well 

as to their equivalent throughout Canada, is applied the term. Laurentian series, from the Laurentide range of mountains from lake Huron to 

Labrador, which are composed of this rock.

LoGrAN, 10 in 1859, gives an elaborate description of the distribution of 

the limestones along the Eouge river. There are found to be two belts 

which are regarded as interstratified with the gneisses. This latter 

rock is sometimes garnetiferous and occasionally is spoken of as the 

quartzite. The total thickness of rocks exposed on the Eouge is over 

22,000 feet, of which over 5,000 is limestone.

LOGAN, U in 1860, finds three belts of limestone, which are associated 

with massive orthoclase gneiss, mica-slate, hornblende rock, and quartz 

rock together 15,000 feet thick. The calcareous bands are largely associated with labradorite, and beds of hornblende rocks and quartz rocks 

often thickly studded with pink garnets. One of the beds of pure white 

quartz rock is a thousand feet thick. Certain fossil-like forms have 

been found which resemble Stromatocerium. The strata are very much 

folded.

LoCrAN,12 in 1863, gives a general account of the pre-Potsdam rocks, 

which are called Azoic and are divided into the Huronian series and 

the Laurentian system. In the Laurentian system are included anorthosite, orthoclase-gneiss, granitoid gneiss, quartzite, hornblende-schist, 

mica-schist, pyroxene and garnet rocks, limestones and dolomites. The 

anorthosites are composed of lime-soda feldspar, varying in composition from andesine to anorthite, and associated with pyroxene or 

hypersthene. The orthoclase-gneiss has a never failing constancy in 

the parallelism of its mineral constituents, which, however, is sometimes obscure. This rock is usually very feldspathic and "often coarse 

grained. With the feldspar and quartz are often mica and hornblende. 

The gueisses appear to attain several thousand feet in thickness, but 

are divided at unequal intervals by hornblende and mica-schist in 

which the stratification is more distinct. The quartzites are in considerable volume, two layers of which, nearly pure, have one a thickness 

of 400 and the other a thickness of 600 feet. The masses of limestone 

are generally very crystalline and coarse grained, but sometimes are 

saccharoidal. The bands of limestone are sometimes of great thickness. They are usually not pure, but contain many other minerals, 

among which are very frequently mica and graphite. Among the 

rarer minerals is chondrodite. The iron ore, which is mostly mag
26 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULi,.86.

uetite, is interstratified with or not far removed from the limestone 

bands. Associated with the limestones are dolomites, which, however, 

compose distinct beds.

There is not any special order in the masses, but beds of hornblende 

rock and hornblende schists are more abundant near the interstratifled 

bands of limestone than elsewhere, and in the same neighborhood there 

usually occurs a more frequent repetition of beds of quartzite than in 

other parts. Garnet is sometimes disseminated in the micaceous and 

hornblendic gneiss and quartzite and are commonly confined to the 

immediate proximity of the limestones. The limestones and gneiss 

beds as a whole are generally conformable to them. It often happens 

that a subordinate layer of gneiss will display contortions of the most 

complicated description. Notwithstanding the highly crystalline condition of the Laurentian rocks, beds of unmistakable conglomeritic 

character are occasionally met with. These generally occur in the 

quartzite or micaceous beds. The intrusives of the Laurentian consist 

chiefly of syenite and greenstones. The greenstone dikes are always 

interrupted by the -syenite when they have been found to come in contact with it, and the latter is therefore of posterior date. A mass of 

intrusive syenite occupies an area of about 36 square miles in the 

townships of Grenville, Chatham, and Went worth. It is cut and penetrated by masses of a porphyritic character which are therefore of a 

still later date.

The Laurentian series stretches on the north side of the St. Lawrence 

from Labrador to Lake Huron, and occupies by far the larger portion 

of Canada. Its strata probably possesses a very great thickness. To 

determine the superposition of the various members of such an ancient 

series is a task which has never yet been accomplished, and the difficulties attending it arise from the absence of fossils to characterize its 

different members. Bands of crystalline limestones are easily distinguished from the bands of gneiss, but it is scarcely possible to know 

from local inspection whether any mass of limestone in one part is 

equivalent to a certain mass in another part. They all resemble one 

another lithologically. The dips avail but little in tracing out the structure, for in numerous folds in the series the dips are overturned, and the 

only reliable mode of working out the physical structure is to continuously follow the outcrop of each important mass in all its windings as 

far as it can be traced, until it becomes covered by superior strata, is 

cut off by dislocation, or disappears by thinning out.

Several sections are described in detail. The general section is as 

follows, in ascending order: Orthoclase-gneiss, 5,000 feet; Trembling 

lake limestone, 1,500 feet; orthoclase-gneiss, 4,000 feet; Great Beaver 

lake and Green lake crystalline limestone, including interstratified beds 

of garnetiferous and hornblendic gneiss, 2,500 feet; orthoclase-gneiss, 

the lower part having several bands of quartzite, 3,500 feet; Grenville 

crystalline limestone, 750 feet; orthoclase-gueiss, 1,580 feet; Proctor's
EASTERN ONTARIO AND WESTERN QUEBEC. 27

lake limestone, 20 feet; orthoclase-gneiss, including quart/ite, 3,400 

f$et; anorthosite, thickness (wholly conjectural), 10,000 feet; total, 

32,750 feet. In the limestones are fossil-like forms which resemble 

Stromatopora rugosa. Accompanying the account of the Laurentinn is 

a detailed map of it in parts of the counties of Terrebomie, Argenteuil, 

and Two Mountains.

The anorthosite probably overlies the Grenville series uncomformably. 

It is remarked that if the two inferior limestone bands of the Grenville series disappear on reaching the margin of the anorthosite, it is 

conclusive evidence of the existence in the Laurentian system of two 

immense sedimentary formations, the one superimposed unconfprmably 

upon the other, with probably a great difference of time between them.

LoGAN,12 in 1863, first describes a part of what was later called the 

Hastings series. In ascending order are found contorted gneiss and 

micaceous schists cut by red syenite veins. Above this comes crystalliae limestone, and north of the village of Madoc, still in ascending 

order, occurs a somewhat micaceous schist, which contains numerous 

fragments of rock in character different from the matrix, some of them 

resembling syenite or greenstone. The pebbles are in places distinctly 

rounded.

BiGSBY, 13 in 1864, states that crystalline limestones occur in bands 

from 50 to 1,500 feet thick at Gananoque, on the lake of the Thousand 

isles, and on the Mattawa. The bands of marble are tortuous, and 

between them are sometimes found corrugated seams of gneiss. Conglomerates and grits occur at Bastard, on the Ottawa, and at Madoc, near 

lake Ontario. At the former place, between the beds of marble, is 

quarteose sandstone, with pebbles of calcareous sandstone and vitrified 

quartz. At M-adoc village are interstratified marble and conglomerate, 

one being bluish micaceous schist, holding fragments of greenstone and 

syenite, the other being a dolomite with large pebbles of quartz, feldspar, and calcite. As proofs of life are the occurrence of limestone, 

carbon, phosphorus, sulphur, and iron ore. The Laurentian system as 

a whole consists of, (1) orthoclase-gneiss, sometimes granitoid, with 

quartzite, hornblendic and micaceous schists, pyroxene, and garnet 

rock; (2) white crystalline limestone and dolomites, in numerous thick 

beds, containing serpentine, pyroxene, hornblende, mica, graphite, iron 

ores, apatite, fluor, etc., and interstratified with bands of gneiss; (3) 

lime-feldspar rock, or anorthosite, containing hypersthene, ilmenite, 

pyroxene, horneblende, graphite, etc. These three groups are traversed 

by granitic and metalliferous veins.

MACFARLANE, 14 in 1866, describes the Laurentian rocks of several 

towns in the county of Hastings. The rocks here found include granite, 

granite-gneiss, gneiss, petrosilex, conglomerates, and limestones. At 

Madoc are conglomerates consisting of pebbles, generally of quartzite, 

in a schistose matrix, lithologically not unlike some of the Huroniau 

rocks.
28 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BOLL.86.

LoGAN, 15 in 1866, farther describes the distribution and structure of 

the O ttawa Laurentian limestone. Th ere are here three great conforii^ible bands, which are termed the Grenville, Green lake, and Trembling 

lake bands. In these limestones Eozoon is found.

LOGKAN, 16 in 1867, states that the Hastings series is arranged in the 

form of a trough, and that to the eastward, and probably beneath them, 

are rocks which resemble those of the Grenville, and it is supposed 

that the Hastings series is somewhat higher than the Grenville. The 

Madoc limestone is overlain unconforinably at several places by the 

horizontal Lower Silurian limestone. In Tudor the limestone is suddenly interrupted for a considerable part of its breadth by a mass of 

anorthosite rock, rising 150 feet above the general plain, which is supposed to belong to the unconformable Upper Laurentiau.

VENNOB,17 in 1867, gives the ascending section of Laurentian rocks 

in Hastings county as follows: Red feldspathic gneiss, 5,000 feet thick; 

dark green chloritic slates, 200 feet; crystalline limestone, 2,200 feet; 

siliceous and micaceous slates, 400 feet; bluish and grayish mica-slates, 

500 feet; pinkish dolomite, 100 feet; micaceous limestone or calc-schist, 

containing Eozoon, 2,000 feet; green diorite slates, 7,500 feet; reddish 

granitic gneiss, 2,100 feet; total, 20,000 feet.

DAWSON 18 (Sir William), in 1869, states that the graphite of the Laurentian is scattered through great thickness of limestones, and is found 

also in veins. In one bed of limestone 600 feet thick the amount of 

disseminated graphite must amount to as much as a solid bed 20 or 30 

feet thick. The graphite is believed to be of organic origin because, 

first, it contains obscure traces of organic structure; second, its arrangement and microscopical structure corresponds with that of micaceous 

and bituminous matter in marine formations of modern date; third, if 

of metamorphic origin, it has only undergone the metamorphosis which 

is known to affect organic material of later age; fourth, it is associated 

with beds of limestone, iron ore, and metallic sulphides, presumably of 

organic origin.

VENNOR, 19 in 1870, in a report on Hastings county, describes the preSilurian rocks. The rocks are divided into three divisions, A, B, and 

C. A, the lower division, consists of syenite rock, granitic gneiss, 2,000 

feet; fine-grained gneiss, sometimes hornblendic and passing into micaschist, 10,400 feet; crystalline limestone, 400 feet. B, tfye middle division, is of hornblendic and pyroxenic rocks, including diorite and diabase, both massive and schistose, 4,200 feet. C, the upper division, 

consists of crystalline and granular limestone, 330 feet; mica-slates interstratified with dolomite, sometimes conglomeratic, with pebbles of 

gneiss or quartzite 1 to 12 inches in diameter, 400 feet; slate interstratified with gneiss, 500 feet; gneissoid micaceous quartzites, interstratijfied \yith siliceous limestone, 1,900 feet; gray micaceous limestone, 1,000 

feet. Total, 21,130 feet. The syenite in certain localities has no apparent marks of stratification. Associated with the above rocks are
VANHISE.] EASTERN ONTARIO AND WESTERN QUEBEC. 29

deposits of iron ore. Eozoon canadense occurs in the topmost member 

of the upper division (C). Division B rests immediately upon A, but 

whether conformably or not is not determined, as the basal members of 

B are massive diorites and greenstones.

VENNOE,20 in 1872, applies to the lowest division of the Hastings 

series (A), the term Laurentian, and the middle division (B) is placed 

as probable Huronian. The rocks of the upper group are found to lie 

uncouformably upon the gneisses and crystalline limestones of the lowest, and it is probable that the middle group is uncouformably below 

the upper and unconformably above the lower group.

VENNOE,21 in 1872, reports on Leeds, Frontenac, and Lanark counties, 

Ontario. The granite of the gold-bearing rocks is believed to represent eruptions which took place probably toward the close of the Laurentian period, or at some time prior to the deposition of the rocks of 

divisions B and C, for, whenever these higher rocks are wanting, the 

Laurentian gneisses, quartzites, and limestone are cut by a network of 

veins.

VENNOE,22 in 1873, gives an additional report upon the counties of 

Frontenac, Leeds, and Lanark. The area is divided into western, middle, and eastern sections. In the western section the main mass of 

rocks is of granite, syenite, and coarse and fine grained gneisses. The 

red granites sometimes appear to be of later date than the white micagranites and even of the diorites of division B. o Limestone was not observed. In a trough between two granite and gneiss areas are found 

diorite-slates, micaceous and chloritic schists, pyroxenic rocks, conglomerates, dolomites, and sandy crystalline limestones. In one conglomerate the pebbles of quartz in a matrix of sand and mica are flattened out along the plane of bedding, so that those which in cross 

measurement are not more than one-fifth of an inch broad have a length 

of from 5 to 10 inches. In places in the conglomerate, ID stead of pebbles, are layers of vitreous quartz or quaxtzite and mica-schist. The 

middle section is undoubtedly Lower Laurentian. The rocks met with 

include great thicknesses of gneiss, for the most part clearly stratified, 

with well defined strike and dip; masses of hornblende rock and diorite, 

graduating into slate or schist; large and important bands of crystalline limestones, and groups of calcareous strata associated with micaslates, and workable masses of magnetic iron ore. These rocks are 

clearly interstratified. Apparently five distinct bands of crystalline 

limestone a>re met with, separated by reddish granitic and dark hornblendic gneisses. The rocks of the eastern section consist chiefly of 

gneiss, but associated with this are coarsely granular limestones. The 

horizontal limestones of the Lower Silurian by a fault are brought into 

abrupt vertical contact with the Laurentian gneiss.

VENNOE,23 in 1874, further describes Frontenac, Leeds, and Lanark 

counties. The five belts of crystalline limestones mentioned in the previous report are described in detail. Eozoon occurs abundantly in 

places.
80 PRE-CAMBRIAN ROCKS OP NORTH AMERICA. [BULL,86.

VENNQR,24 in 1876, gives a further report on the rear portions of Frontenac and Lanark counties. Two sections are given,, representing the 

limestones asinterstratified with the quartzites and gneisses. The rocks 

are classified into five groups: I, Mica-schist group; II, Dolomite and 

slate group; III, Diorite and hornblende-schist group; IV, Crystalline 

limestone and hornblende-rock group; Y, Gneiss and crystalline limestone group. A sixth group, described in a previous report, occupies 

the front portion of Lanark county. Each of the five groups have 

many subordinate phases of rocks; they occupy distinct and separate 

positions, but it is not known whether they represent one or more formations.

VENNOR,25 in 1877, states that there is in eastern Ontario and the 

adjoining portions of Quebec an Azoic formation, consisting of syenite 

and gneiss(?), without crystalline limestone, in which there is but little 

indication of stratification. On it has been unconformably deposited a 

great system of gneisses, schists, slates, crystalline limestones, and 

dolomites, in the higher member of which Eozoon is found. The limestone occurs in four principal belts. Both Logan's Huronian and Upper 

Laurentian are considered to belong to the second division, which is for 

the present called the Upper Laurentian. Interstratified with several 

of the bands of limestone are labradorite rocks. No evidence is found 

for making these a distinct system. The Huronian and Hastings series 

are simply an altered condition in their westward extension of the 

lower portion of the upper system.

VENNOR,26 in 1878, reports on the counties of Benfrew, Pontiac, and 

Ottawa. Beferring to the work of previous years, it is said that the 

rocks of divisions B and G of the Hastings series are really the western 

extensions of the diorites, hornblende-schists, and mica-slates of Lanark 

and Beufrew counties, in other words, of groups I, II, and III; and 

these last have also been shown to be a low portion of the gneiss and 

limestone series, that is, groups IV, V, and VI; and these have always 

been looked upon as typical Laurentian. The conclusion is consequently 

reached that the Hastings series is not, as it has been considered to be, 

the most recent, but rather the oldest portion of this great system of 

rocks investigated. It is also clear that this great crystalline gneiss 

and limestone series rests upon a still older gneiss series, in which no 

crystalline limestones have yet been discovered. This series is the one 

referred to as division A, where limestones have been mentioned, but 

incorrectly. This occupies many hundreds of square miles between the 

St. Lawrence and Ottawa rivers, and is the rock which forms the backbone of eastern Ontario and the nucleus around which have been deposited all succeeding formations. This, then, is undoubtedly Archean 

and Lower Laurentian, and consequently the crystalline limestones 

and gneisses constitute a series which would come in beneath Logan's 

Upper Laurentian or Labradorite series. Whether this latter exists 

as a distinct formation is doubtful. In each instance in which the
YANHISE.] EASTERN ONTARIO AND WESTERN QUEBEC. 31

crystalline limestones have been found in the interior of the gneiss 

country, these have been proved to occur in the superficial condition of 

shallow troughs, and not as bands interstratifted in the gneiss itself.

The lower noncalcareous Laurentian is a great series of crystalline 

rocks, not only highly metamorphosed, but most intricately contorted. 

In the entire area studied the gneiss and syenite are by far the most 

abundant rocks, while gneisses with interstratifted crystalline limestones occupy but a comparatively limited area, and this only toward 

the margins of the former. The relative volumes of the two distinct 

sets of rocks, that is, the gneisses with the crystalline limestones, bear 

about the same relations to the volume of gneiss and syenite that the 

comparatively narrow belt of the Silurian does in this section of country 

to both of these together.

There is thus in these old crystalline rocks a great uncalcareous division and a smaller calcareous one. The first of these may be further 

subdivided into a stratified and uustratified portion, of which the latter 

is undoubtedly the lowest and oldest. As shown by the map, north 

and northwestward of the line, at the base of the gneiss and limestone 

series, there are numerous and repeated troughs of the lower member 

of this division which separate out over the great fundamental gneiss 

system in a most irregular manner, and it is these that have given rise 

to the supposition that the older gneiss and syenite is iuterstratified 

with the crystalline limestone. The three great subdivisions in eastern Ontario are, then, first, a great gneissic and syenitic series without 

limestone; second, a thinner gneissic series with labradorites and limestones j and, third, Lower Silurian (Potsdam to Trenton). The thickness of the upper series, exclusive of the fundamental gneiss, is placed 

tentatively as from 50,000 to 60,000 feet. No attempt is made to estimate the thickness of the underlying gneiss and syenite series.

BELL,27 in 1878, reports on geological researches north of lake Huron 

and east of lake Superior, including lake Nipissing. He finds the rocks 

along the whole northeast coast of Georgian bay, a distance of 125 miles, 

to belong to the Laurentiau series. They consist principally of varieties of gneiss, occasionally interstratified with bands of hornblendic and 

micaceous schists. The crystalline limestones are also found, as well 

as stratified diorites, trap rocks, and granite veins. The rocks have 

no uniform strike and are contorted into many anticlinals and synclinals. The crystalline limestones of Georgian bay and lake Nipissing are 

regarded as belonging in three and possibly more crystalline bands. 

Associated with the limestone are sometimes found chert, conglomerate, 

quartzite, and magnetic iron ore. A junction of the granite with the 

Huroniau quart/ite and hornblende-schist is mentioned.

WiLKiNS,28 in 1878, describes near the Grand Trunk station of Shannonville, about three-quarters of a mile north of the village, a gray ami 

green slate conglomerate which much resembles the slate conglomerate 

of lake Huron belonging to the Huronian system. The base of this
32 PRE-CAMBRIAN BOOKS OF NORTH AMERICA. [Buu,g8.

rock is a schistose gray orthoclase with green hornblende and epidote, 

while the pebbles are of Laurentiau gneiss., white and red micaceous 

and syenitic granite, 'syenite, felsite, dolerite, diorite, epidote, chlorite, 

and quartz, these masses being generally rounded, particularly the 

gneissic pebbles, and very rarely angular, while in size some exceed a 

foot in diameter, and others are not over 2 or 3 inches. At Gibson's 

mountain, 6 miles southwest of Belleville, occurs Laurentian porphyritic 

coarse grained granitoid syenitic gneiss.

SELWYN,29 in 1879, states that it has been conclusively demonstrated 

that the Grenville and Hastings groups, consisting of limestones and 

calcareous schists holding Eozoon, with associated dieritic, felsitic, micaceous, slaty, and conglomeratic rocks, form one great conformable 

series, which rests quite unconforniably upon a massive granitoid, syeiiitic, or red gneiss series, and are unconformably below the Potsdam or 

Lower Silurian rocks. The same may be said of the Huronian series 

of Georgian bay, which at lake Nipissing include some labradorite 

gneiss, and it is very probable that a connection will eventually be 

traced out between these supposed greatly different formations like that 

now proved to exist between the Hastings and Grenville series. The 

Norian series is thought to be a part and parcel of the great crystalline 

limestone series. These anorthosites are thought to represent the volcanic and intrusive rocks of the Laurentian period, and if so, their 

massive and irregular, and sometimes bedded appearance, and the fact 

that they interrupt and cut off some of the limes tones, is readily understood. Chemical and microscopical investigations both seem to point 

to this as the true explanation of their origin. That they are really 

eruptive rocks is held by nearly all geologists who have carefully 

studied their stratigraphical relations.

SELWYN,30 in 1884, finds from. Pembroke to Wahuahpitae river on 

the Canadian Pacific railway, nothing but Laurentian, which consists 

of red, gray, and white orthoclase gneiss, black hornblende-schists and 

mica-schists, often garnetiferous, pyroxenic gneiss banded like Eozooii, 

and large bands of crystalline limestone. These rocks are all very distinctly stratified, and dip generally in an easterly direction at augles 

varying from almost horizontal to vertical.

SUMMAKY OF KESULTS.

It is apparent that the great area, roughly bounded by Georgian bay, 

the Ottawa and St. Lawrence rivers, to which the term Laurentian is 

applied, is, as a whole, a very crystalline one. This is so far true that no 

attempt has been made over the greater part of the area to stratigraph 

ically subdivide the rocks. The exceptions to this are a small area in 

Argenteuil and adjacent counties, and a strip of country running from 

Ottawa to Madoc. Even in the districts in which the detailed maps 

are given there is no estimate of the thickness of the layers of the more 

massive parts of the series.
VANHISE.] EASTERN ONTARIO AND WESTERN QUEBEC. 33

In discussing the stratigraphicai succession, large areas of the rocks, 

including syenite, granite, porphyry, etc., can be excluded, for it is certain, as was early recognized byLogan and Murray, that many of these 

rocks are eruptives of later age than the gneissic and schistose rocks 

. with which they are associated.

Logan, Murray, and Vennor in his final comprehensive review, reached 

the same stratigraphicai conclusions. Occupying the inferior position 

in this region is an immense thickness of syenitic, granitic, and gneissic 

rocks. For the most part thisjower division is intricately folded, and if 

it has a stratigraphy, it is of so complicated a character that no estimate is made of the thickness. Where a structure is present there is 

no evidence that it is due to sedimentation. It contains no bedded 

limestones, no carbonaceous schists, no elastics, either volcanic or waterdeposited. It is, then, a complex, devoid of any structure which has 

been shown to be bedding, devoid of any materials which may not be 

of other than surface origin. As described by Yeniior, this lower noncalcareous Laurentian covers the larger part of the region. That limestones were at one time supposed to be contained in this series is explained by him to be due to the fact that overlying bands of the upper 

 division are included as infolded troughs.

Upon these rocks rests a series of a very different lithological character. It includes great thicknesses of limestones, quartzites, conglomerates, hornblende-schists, mica-schists, and bedded gneisses. If the 

limestones, quartzites and the regularly bedded character of the gneisses 

are not sufficient evidence of a clastic origin, the presence of unmistakable conglomerates at numerous points is conclusive. This clastic 

series, as shown by the descriptions of it in the vicinity of Madoc, is in 

part clearly volcanic. The very great estimated thickness of this bedded series may be questioned, for evidently the study was not close 

enough and the structure well enough determined to decide this difficult 

question.' The equivalence of the clastic rocks of the different districts 

has been assumed, but those more distant from the type area differ considerably from it in lithological character as well as from each other. 

That they are really equal has not been shown, although this is probable for certain of the districts.

As to the anorthosite series it may be excluded from*the bedded 

succession. It is now believed by most geologists that this rock is an 

eruptive. The unconformity at its base is an eruptive one, in all probability caused by the outflowing of this rock at a later period than the 

formation of the underlying series.

The Laurentian clastic series of the type area resembles, to a remarkable degree, the bedded gneisses, limestones, graphitic schists, 

and quartzites of the Adirondacks, except that the latter have become 

more completely crystalline. The core of the Adirondacks is " anorthosite rock," really gabbro, and away from this the bedded series 

dips in a quaquaversal manner, so that the anorthosites apparently 

Bull. 86 3
34 PRE-CAMBEIAN ROCKS OF NORTH AMERICA. [DULL. 86.

underlie the elastics. This is explicable by regarding the anorthosite 

as an intrusive which has pushed up the bedded elastics, causing the 

latter to dip away from it in every direction. In the Ontario area it 

appears that the " anorthosite" has actually burst through and overflowed the elastics.

Comparing the bedded clastic division of the Laurentian with the 

Original Huronian, the description of the latter by Bell at Nipissing 

approaches closely in lithological character that of the Huronian, to 

which division the series was referred by Selwyn. The clastic series 

in the vicinity of Madoc, before Vennor realized that it is probably 

a continuation of that to which the term Laurentian was applied at 

Ottawa by Logan, was considered as Hurouian, and by Logari himself 

was supposed to be higher than the Grenville series.

These two districts are intermediate in position as in character between 

the type areas of upper Laurentian and the Huronian.

The elastics of the Laurentian nowhere come in contact with those oi 

the Original Huronian area, so that we have no evidence whatever as 

to their relative age. The former are underlain by a banded and contorted gneissic and granitic series. The same is true of the Huronian 

of lake Huron. In this latter area the clastic series rests unconformably upon a lower gneissic one, but in eastern Ontario we have no 

positive evidence that similar relations obtain; but it is not improbable, as maintained by Yennor, that there is at the base of the clastic 

series a true unconformity. On the other hand, it is possible that the 

relations between the clastic series and the underlying completely crystalline series are those of sedimentary rocks and later intrusives.

Bearing in favor of an unconformity between the lower granite-gneiss 

and at least a part of the clastic series are several lines of evidence: 

(1) In Leeds, Frontenac, and Lanark counties the granites which cut the 

Laureutian gneisses in a network of veins never penetrate the series of 

quartzites, conglomerates, limestones, etc., although sometimes found 

in Vennor's middle or dioritic division. This indicates that the granite-gneiss not only existed but had been intruded by granitic eruptions 

before the elastics were deposited. (2) The abundant large pebbles 

and bowlders of granite and syenite found at many localities in the 

Laurentian region, and particularly about lake Nipissing and near 

Shannonville, show that earlier than the elastics existed gneisses 

and granites identical in character with those now designated as Laurentian. The probability is that these pebbles are, as supposed by 

Logan and Wilkins, derived directly from the Laurentian. If this is 

the case, between the two must have existed a great time gap, for these 

fragments when deposited show that the rocks from which they are 

derived were then at the surface in their present completely crystalline condition. (3) The rocks of plainly clastic origin are associated and 

occur in trough-like areas, although having mterstratified with them 

comparatively thin belts of gneiss, which, however, may be meta-
U.S.GEOLOGICAL SURVEY. 

Gray Quartzite

Green Chlorite Slate 

I Lower White Quartzite 

] Lower Slate Conglomerate 

I Limestone 

"1 Upper Slate Conglomerate

g [ 1 Red Quartzite

h [_. ""! Red Jasp.Conglomerate

i r~~1 Upper White Quartzite

k F I Yellow Chert & Limestone

I i "1 White Quartzite. Chert & Limestone

MAP OF THE ORIGINAL HURONIAN ROCKS

(After Lo^afr) 

Scdle soe.'sifo
VAN HISE.] LAKE HURON TO LAKE TEMISCAMANGL 35

inorphosed sedimentaries. Tliat this series is newer than the granitegneisses, is indicated by the fact that the intricate structure of the 

lower Laurentian is not simulated by the clastic rocks. Apparently the 

latter has undergone earlier and more intense orographic movements 

than the former.

SECTION II. FROM NORTH CHANNEL OF LAKE HURON TO LAKE

TEMISCAMANG-.

LITEKATUUE.

BiGSBY,31 in 1821, gives the earliest geological account of the north 

shore of lake Huron. He found north of the North channel two series 

of rocks, one of granite, gneiss, and trap, which was placed by him 

with the Primitive; the other, without mentioning distinct characters, 

he called the Transition formation.

MURRAY,32 in 1845, finds Primary and Metamorphic rocks to comprise the whole country to the north of lake Simcoe and the northeastern shores of lake Huron. The rocks are similar in appearance to the 

masses which compose the Thousand isles, and include granite, syenite, 

and gneiss, as well as a coarse micaceous sandstone, which at one place 

presents evidence of stratification.

L/OGAN,33 in 1847, finds, after passing over 63 miles of lower metamorphic or syenitic gneiss on the Ottawa, after leaving the Mattawa 

(Hearing lake Temiscamang), a succession consisting of (1) chloritic 

slates and conglomerates, (2) greenish sandstones, and (3) fossiliferous limestones. The conglomerates often hold pebbles and bowlders, 

sometimes a foot in diameter, of the subjacent 'gneiss, from, which they 

are chiefly derived. So indurated is the rock that the fracture breaks 

across the pebbles. The sandstone is of a sea-green color, and appears 

to be composed of quartz and feldspar, with occasional flakes of mica. 

The volume of (1) is probably not less and may be very much more 

than 1,000 feet, while that of the sandstone is between 400 and 500 feet. 

Formation (3), fossiliferous limestone, is often conglomeratic at its base, 

containing pebbles, fragments, and bowlders of the sandstone beneath 

in a calcareous cement. Some of the harder beds abound in chert and 

many of them are fossiliferous, the organic remains leading to the opinion that this rock is equivalent to the Niagara of New York. That 

these limestones are unconformable with the slates appears almost certain, but whether the intermediate sandstones are conformable with 

one or both of these can not be asserted, nor can it be asserted that 

the slates are conformable with the gneiss.

LoCKE,34 in 1847, having visited Echo lake and the Bruce mine, finds 

the rocks of the North channel to consist of sandstone, talcose slate, 

limestone, all metamorphosed by trap rock. The slate contains some 

pebbles of primitive rock, and thus approaches a conglomerate. The 

limestone at Echo lake shows original stratification, and is traversed
36 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

by seams of hard metamorphic slate, being nearly in the condition of 

a jasper. They are undulated, contorted, and pleated in a beautiful 

manner.

CHANNING,35 in 1847, reports on an examination of Sugar island, 

Sailors Encampment island, St. Joseph island, and the main shore to 

Sault Ste. Marie on the American side. Metamorphic sandstone 

quartz, chlorite-slate quartz, feldspar rock quartz, chlorite, granite, 

syenite are all found, and are constantly intersected by the trap dikes. 

At Echo lake is a metamorphic sandstone quartz, containing a stratum 

of pebbles converted into jasper. On Sugar island is found metamorphic sandstone, containing fragments of metamorphic sandstone and 

gray gneiss.

MURRAY,36 in 1849, describes the continuation of his work on the 

north coast of lake Huron west of French river, and upon the adjacent 

Manitoulin islands. The pre-Potsdam group of rocks consist, firstly, 

of a metamorphic series, composed of granitic and syenitic rocks in 

the forms of gneiss, mica-slate, and hornblende-slate; and, secondly, in 

ascending order, of a stratified series, composed of quartz rock or sandstoues, conglomerates, shales, and limestones, with interposed beds of 

greenstone. The first of these series is in so highly a disturbed condition, and is so much contorted that it is impossible to ascertain its 

thickness. The second series occupies the whole north coast of lake 

Huron, with many of its neighboring islands between little lake 

George and Shebawenahning. The breadth of country this series 

occupies, and the thickness it attains, there was no opportunity of 

determining. The quartzites sometimes pass into a sandstone, and 

into a beautiful conglomerate, whose pebbles are chiefly of blood-red 

jasper. Besides the jasper conglomerates there are other conglomerates, the pebbles and bowlders of which are of syenite, varying from 

those of small size to those 2 feet in diameter; and these are sometimes in a greenish quartz rock as a matrix, and sometimes in a 

greenish slate, more frequently the latter. Numerous greenstone dikes 

traverse the stratified series, and greenstone masses are interposed 

among the sedimentary beds. On some small islands granite veins 

and trap dikes were found breaking through the quartz rock, on one of 

which the latter beds dipped in opposite directions on opposite sides of 

the granite, and on another the quartz rock was found reclining on the 

granite, the contact being seen. The fossiliferous series is supported 

unconformably upon the older rocks.

LoGAN,37 in 1849, next gives a general account of the geology of the 

north shore of lake Huron. An area of rocks, 120 miles long, and from 

10 to 20 miles wide, is placed 'in a single formation. This formation 

rests unconformably below the Silurian, as shown by the fact that the 

latter horizontal strata rest upon the uptilted edges of the quartz rock, 

fill the valleys between, and overtop the mountains. Upon account of 

the eruptive material which the formation 'contains it is placed as the
VANHISE.] LAKE HURON TO LAKE TEMISCAMANG. 37

probable equivalent of the copper-bearing group of lake Superior. 

The series is divided into rocks of sedimentary and rocks of eruptive 

origin. The sedhnentaries consist of sandstones, conglomerates, slates, 

and limestones. The greenstones are of igneous origin, and are of two 

classes, intrusives and overflows. The intrusives are in part as sheets 

and in part as dikes. The various kinds of sedimentary beds grade 

into each other, while the greenstones do not thus grade into the sediments, and therefore present a strong contrast to the real sedimentary 

beds. The dikes and overflow sheets are lithologically alike, and the 

dikes reveal a history which has two or three episodes. The chief difference in the copper-bearing rock of lakes Huron and Superior seems 

to lie in the great amount of amygdaloidal trap in the latter, and of 

white quartz or sandstone in the former, but there are strong points of 

resemblance, SO it is highly probable, if not almost certain, that they 

are equivalent and beneath the lowest fossiliferous deposits. On the 

east and west the series seems to repose on granite, 

o MURRAY,38 in 1850, gives the result of a survey of the Spanish river. 

Upon this stream he finds exposed a granitic or metamorphic group and 

a quartz-rock group. The latter contains quartzites, slates, and conglomerates, holding sometimes pebbles of jasper, but more often of syenite or granite, as well as limestones and dikes and beds of intrusive, 

greenstones, and can scarcely be less than 10,000 feet thick. The granitic group appears to rise from beneath the metamorphic group at two 

places.

LOGA.N,39 in 1852, states that on lake Huron the Lower Silurian group 

rests unconformably upon a siliceous series, containing one band of 

limestone about 150 feet in thickness, having leaves of chert, but without discovered fossils. The series is the copper-bearing rocks of that 

district, is interstratified with igneous masses, and has a thickness of 

at least 10,000 feet; it is supposed to be the Oanibrian epoch. The 

gneissoid group is probably still older, and its condition is such as to 

make it reasonable to suppose that it consists of altered aqueous deposits.

MURRAY,7 in 1857, describes several of the more important streams 

between Georgian bay and lake Mpissing. They embrace two of the 

oldest recognized geological formations, the Laurentian and Huronian; 

the rocks of the latter are more recent and have been observed to pass 

unconformably below the lowest of the fossiliferous strata of the Silurian system. The contorted gneiss of the Laurentian series, with its 

associated micaceous and hornblendic schists, spreads over the country 

to the south and east, while the slates, conglomerates, limestones, 

quartzites, and greenstones of the Huronian occupy the northern and 

western parts. The difference in lithological character between the 

two formations is always sufficiently apparent, but though both were 

found a short distance apart, the immediate point of contact was always
38 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

obscure, and a mass of greenstone of rather coarse grain was usually 

the first intimation of the proximity of the higher rocks. Whether this 

greenstone is a contemporaneous flow or subsequent intrusion has not 

been ascertained. The lower slates stand nearly vertical on Sturgeon 

river near the gneiss. The following is the general succession within 

the Huronian, in ascending order: fine grained siliceous slates5. slateconglomerate, containing profuse syenite and occasional jasper pebbles j 

limestone; slate-conglomerate, like the first; green siliceous chloritic 

slate; and close grained quartzite of various colors running into a 

conglomerate, the pebbles of which include white quartz and red and 

green jasper. The thickness of the Huronian is calculated at 10,000 

feet and corresponds with the determination of the thickness of the 

quartz-rock series on the Spanish river.

LoGAN,40 in 1858, applies the term Huronian to the copper-bearing 

rocks of lake Huron. A limestone near the middle of the series is used 

to trace out the structure.

MURRAY,41 in 1858, gives a continuation of his study of the rocks. 

north of lake Huron. He places the rocks of French river, described 

in the report of 1857, as Laurentian. A belt of limestone 200 feet thick 

is used in working out the structure of the Huroniau. The Huronian 

is also called the copper-bearing rocks.

LOGAN,42 in 1858, gives a general description of the pre-Silurian 

Azoic rocks of Canada, which occupy nearly a quarter of a million 

square miles.0 These are a series of very ancient sedimentary deposits 

in an altered position. They are of great thickness and are capable of 

division into stratigraphical groups. In the formation about lake Temiscamang are sandstones, quartzose conglomerates, and slate conglomerates, the slate conglomerates holding pebbles and bowlders derived

from the subjacent gneiss. o The bowlders display red feldspar, translucent quartz, green hornblende, and black mica, arranged in parallel 

layers, which present directions accordant with the attitude in which 

the bowlders were accidentally inclosed. From this it is evident that 

the slate conglomerate was not deposited until the subjacent formation had been converted into gneiss, and very probably greatly disturbed; for while the dip of the gneiss, up to the immediate vicinity of 

the slate conglomerates, was usually at high angles, that of the latter 

did not exceed 9 degrees. A similar set of clastic rocks is found on 

the north shore of lake Huron, except that the series is here intersected 

and interstratified with greenstone trap, and pebbles of syenite and jasper are found. Eastward of lake Temiscamang, in an area of 200,000 

square miles imperfectly examined, no similar series of rocks has been 

met with. Because this clastic series of rocks occurs in typical development on lake Huron it has been decided to designate it by the teim 

Huronian.

MURRAY,43 in 1859, in continuing his study of the Huronian, gives 

most of his time to the region adjacent to the Thessalon and Mississagui
VANHISB.] LAKE HURON TO LAKE TEMISCAMAKG. 39

rivers. The Huroiiian is found to be in two main troughs and the thickness of the series of formations amounts to 16,700 feet. This thickness, 

greater than that given in the report of 1857, is due to the accidental 

existence here of intercalated greenstones.

BiGSBY,44 in 1862, concludes that the Huronian is greatly older than 

the Cambrian because: (1) Its marked similarity, lithologically, to the 

fundamental gneiss formation. (2) The conformity of these two sets of 

beds. (3) The great interval of time which must have elapsed between 

the periods of laying down the fundamental formation and the Silurian, if we are to judge from the occasionally vast thickness of the Cambrian. Beyond all comparison, the Huronian is more widespread and 

extensive, as well as more uniform in its mineral constitution, than the 

Cambrian group. It is, perhaps, also more important economically.

L/OG-AN, 12 in 1863, gives a general summary of the information as to 

the Huronian series north of lake Huron. This area is mapped in 

detail. It extends along the entire North channel of lake Huron, with 

the exception of a short distance where the Laurentian occupies the 

shore. The full csection on the north shore of lake Huron is as follows, from the bottom upward: (1) gray quartzite, 500 feet; (2) green 

chlorite slate, 200 feet; (3) white quartzite, 1,000 feet; (4) lower slate 

conglomerate, 1,280 feet; (5) limestone, 300 feet; (6) upper slate conglomerate, 3,000 feet; (7) red quartzite, 2,300 feet; (8) red jasper 

conglomerate, 2,150 feet; (9) white quartzite, 2,970 feet; (10) yellow 

chert and' limestone, 400 feet; (11) white"quartzite, 1,500 feet; (12) 

yellowish chert and impure limestone, 200 feet; (13) white quartzite, 

400 feet; total thickness, 18,000 feet. Interstratified with certain of 

these layers, and particularly Nos. 4, 6, 7, 8, and 9 are considerable 

masses of greenstone. That these are contemporaneous overflows iu 

places is indicated by the fact that they are amygdaloidal and are 

arranged in layers. There are, however, also present intrusive masses 

of greenstone and granite, which in the form of dikes cut the stratified 

rocks in many directions. The different sets of dikes are of at least 

three different ages, the granite being intermediate in age between two 

greenstone eruptions. Many of the pebbles of the red jasper conglomerate are' banded, showing their derivation from a more ancient 

stratified rock. South of lake Pakowagaming is a considerable area of 

granite which breaks through and disturbs the Laurentian gneiss, and 

from which emanates a complexity of dikes, the whole being supposed 

to be of Huronian age. The immediate contact of the gneiss with 

the overlying rocks has not been observed. The gneiss between Mississagui and St. Marys rivers has been much disturbed by intrusive 

granite and greenstone, and it is difficult to make out how the stratified 

portions are related to each other. Near Les Clrandes Sables, a gray 

quartzite, supposed to be the lowest Huronian, abuts against one mass 

of gneiss, and runs under another and appears to be much broken by 

and entangled among the intrusive rock. On. lake Temiscamang the
40 PRE-CAMBRIAN ROCKS - OF NORTH AMERICA. [BULL. 86.

Laurentian gneiss is followed by a slate conglomerate which contains 

pebbles and bowlders sometimes a foot in diameter of the subjacent 

gneiss. The Huronian of lake Huron is correlated with the lower copper-bearing rocks of lake Superior. Several detailed sections are 

described. The general sections represent the Hurouian series as 

resting unconformably upon the Laureutian.

LoG-AN,45 in 1865, states that the horizontal strata, which form the 

base of the Lower Silurian in western Canada, rest upon the upturned 

edges of the Huronian series, which in its turn unconformably overlies 

the Lower Laurentiau. The Huronian is believed to be more recent 

than the Upper Laurentian series, although the two formations have 

never yet been seen in contact.

SBLWYN,30 in 1884, west of Wahnahpitae river, on the Canadian Pacific 

railway, for 80 miles, finds Laurentian rocks, which consist of felsites 

or felsitic quartzites, thin bedded quartzites which hold angular fragments of granite and gneiss, diorite and diabase, with a series of coarse 

and fine fragmental beds varying in character from a fine ash to coarse 

agglomerate. *

IitviNG,46 in 1887, summarizes the information of the Canadian Survey 

with reference to the Huronian of lake Huron, and describes a contact 

near Thessalon river between the underlying gneissic series and the 

overlying Huronian. Here a basal conglomerate, containing partly 

rounded and angular fragments up to 2 feet in diameter, largely derived 

from the immediately underlying gneiss, rests directly upon the upturned edges of the gneissic series. Such a contact indicates a great 

structural break, whether the underlying gneissic series is of eruptive 

or of sedimentary origin. If sedimentary, it must have been metamorphosed to its present crystalline condition and upturned before the fraginentals were deposited upon it; if eruptive, its coarsely crystalline 

character shows that it belongs to the deep-seated rocks which must 

have crystallized at depth, and therefore has been subjected to great 

erosion in order that this class of rocks may be found at the surface. 

Such a contact is also found at two or three other points on the Algorna 

branch of the Canadian Pacific railway, an4 particularly at the vicinity 

of the mouth of Serpent river. Logan's 2 green, chloritic slate is composed of diabase sheets and a little interleaved fragmental material, 

perhaps partly volcanic ash,

WINCHELL (N. H.),47 in 1888, describes many localities within the 

Original Huronian. Logan's chloritic slates, as well as the-greenstones, 

are regarded as accidental features, the former being a part of the basic 

eruptive rocks of the region. Yast outflows of greenstone cover many 

square miles in the Thessalon valley and constitute hill ranges as conspicuous as those of any hill rock in the region. This series is classified 

and parallelized with the Minnesota rocks, as follows:
YAH rasa.] LAKE HURON TO LAKE TEMISCAMANG. 41

Original Huronian. Minnesota equivalents.

(Pcwabic quartzite (?). 

Otter Tail quartzite . .^........................ ^ New Ulm^ Pokegama and Waua.

Thessalon quartzite............................ f waugoniug quartzites.

Black slate .................................... Animikio black slate.

"Lithographic stone " and fine gray quartzite . .Not known.

Red felsite..................................... Felsites at Duluth and probably the

Great palisades. 

Mississagui quartzite .......................... Not known.

Slate conglomerate ............................ Oglshki conglomerate.

Chert and quartzite pebbles in the Thessalon quartzite lead to the 

inference that this is unconfbrmably upon the black slate. The existence of granite bowlders in the slate conglomerate indicates another 

unconformity between, it and the granites of the region. In this latter 

case the evidence is conclusive, and in the former it is inconsiderable.

WINCHELL (ALEx.),48 in 1888, also gives many observations upon 

the original Huronian. In the Huronian system is a large volume of 

eruptive rock with a great thickness of rocks of undoubted sedimentary origin, with an equal volume of an obscure slaty character. The 

latter appear to constitute the green chlorite schist of Logau, which is 

either an ancient or much altered eruptive or highly altered sedimentary material. The quartzites contain angular fragments of such a 

character that they seem to be derived from this diabase schist; and 

this circumstance countenances the theory that the latter are older and 

probably sedimentary in origin. The Huronian of Canada, in descending order, is as follows: Otter Tail white quartzite, 4,000 feet; Thessalon red and gray quartzite, 5,000 feet; Otter Tail cherty limestone, 100 

feet; Upper Plummer conglomeratic and siliceous argillite, 500 feet; 

red felsite, granulite, and quartzite, 100 feet; lower conglomeratic and 

siliceous argillite, 7,400 feet; Bruce limestone, 100 feet; Mississagui 

vitreous quartzite, 3,750 feet. This succession includes neither the 

lower nor the upper limit of the Hnronian. At St. Joseph's island the 

Huronian is immediately overlain by a fossiliferous limestone, apparently the Chazy. It thus appears that the Huronian is a system following downward immediately below the Lower Silurian, and if no 

intervening terranes are wanting it occupies the position of the Taconic 

of Emmons and the Lower Cambrian of Sedgwick. The lower limit of 

the Huronian must be succeeded by a formation of vitreous quartz, red 

jasper, and graywacke, besides greenstones, red granulite, red gneiss, 

mica-bearing granite, since fragments of all these are found in the 

Huronian. It may be that the quartzite pebbles are derived from the 

Mississagui quartzite, but the red jasper and greywacke must have 

been derived from a terrane older than the Huronian and newer than 

the crystalline masses of the Laurentian.

BoNNEY,49 in 1888, discusses the development of the crystalline 

schists in the neighborhood of Sudbury. The semicrystallines can be 

easily separated from the thoroughly crystalline rocks of the Lauren-
42 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BUM-. 80.

tian. In the Huronian rocks two groups may be distinguished, one of 

which is slightly altered and the other very much more extensively 

modified. The seruisrystallines are compared with those of like character in-Great Britain. 

BARLOW,SO in 1890, describes the relations between the Hurouian 

and Laurentian north of lake Huron. At many localities the contact 

is found to be an irruptive one, the granite and gneiss intruding the 

Huronian elastics. Very often the Huronian strata dip into or under 

the gneiss, although often the Huronian beds are superimposed upon 

the gneiss in perfect conformity, and occasionally gneiss is seen dipping 

away from the vertical Huronian strata. Huroniau rocks are also seen 

resting unconformably upon the upturned edges of Laurentian gneiss. 

The Huronian strata are often metamorphosed where in contact with 

the gneiss. These different phenomena are all explained by the later 

irruptive character of the gneiss.. It is concluded that the Huronian 

system is the oldest series of sedimentary strata known in this region.

BELL51 , in 1890, states that stretching from lake Huron to lake Temiscamang is the greatest area of Huronian rocks in Canada. The most 

prevalent rock in this region is gray wacke, often conglomeratic'. Another rock of great abundance is a quartz-diorite. These two are the 

parent rocks of the Hurouian. The quartzites and clay-slates are but 

phases of the gray wacke. The rocks of this region show three ways by 

which gneiss may be formed, namely, by the direct conversion of the 

thin bedded or slaty varieties of graywacke, by the alteration of the 

mixed quartz and feldspar rock derived from other varieties of it, and 

by the alteration of the modified quartz-diorites. The dolomites are of 

a concretionary or segregated nature, derived from the hornblende and 

augite of the rocks with which they are associated. During the process 

of conversion from graywacke into syenite, strings and veins of magnetite have formed.

WINCHELL (ALEX.)52, in 1890, gives further observations on the original Huronian region. Northwest of Echo lake is found a series of 

argilJites, slates, quartzites, and schists, which are frequently congloni' 

eratic and in one place contain outcrops of hematite. These strata are 

close to a vertical attitude, strike nearly east and west, and resemble the 

Knife lake series and Ogishki conglomerates of Minnesota. These 

rocks can not belong to the same system as the quartzites, upper 

slate conglomerates, and limestone of the Huronian, which dip at an 

angle of 20°. There is here a genuine discordance of stratification, and 

two series, not one, as mapped by Logan. The lower system is the 

formation which occurs at Gros cap, G-oulais bay, and Dore river, which 

was identified by Logan with the Huroniau of lake Huron. The author 

is convinced also of their identity with the vertical strata in Minnesota 

and Canada known as the Keewatin system. It is also clear that these 

gnarled, green pebble slates are the prolongation of the lower slate conglomerate of the Thessalon valley.
VAKHWR.] LAKE HUIiON TO LAKE TEMTSCAMANG. 43

WINCHELL (ALEX.)53 , in 1891, maintains that the Original Huronian 

is divisible into two unconformable series, the break occurring between 

the upper and lower slate-conglomerates, and the limestone'belonging 

with the upper series. The descriptions of this region by Murray indicate that near lake Wahnapitae there is a stratigraphic unconformity 

between the upper and lower divisions of the Original Huronian, as 

here the slate-conglomerates are in a nearly vertical attitude, while the 

newer members seldom have an inclination greater than 45°. In every 

instance in which the lower slate-conglomerate has been traced by Logan 

or Murray to the proximity of the gneiss these formations seem to be 

conformable in position, though the actual juxtaposition was concealed. 

At Murray hill the slate-conglomerate has a dip to the southward of 

78°, while 2 miles south of this the slate-conglomerate has a dip of 40° 

toward S. 30° w. The first is regarded as the lower slate-conglomerate 

and the second as the upper slate-conglomerate. At the junction of the 

Sudbury branch of the Canadian Pacific railway with Vermilion river 

an arenaceous slaty rock, having a dip of 45°, rests on a different schist 

having a different dip. At this locality, according to Lawson, the 

unconformity is similar to that at Penokee gap, Wisconsin. The lower 

rock is a fine micaceous gneiss or mica-schist, and the upper rock is 

interbedded quartzite and gray argillite. At Echo lake is a series, in 

descending order, of slate-conglomerate and quartzite, with a dip of 

about 20° ; after this is an interval of a third of a mile, and then appears a quartzose slate-conglomerate comparable with the Ogishki conglomerate; this is followed by quartzite, and this by alternations of 

quartette, quartz-schist, and various slates, schists, and argillites, the 

series having a dip of 75° to 80° southwesterly, and being as a whole 

more crystalline than the upper system. It is concluded that the name 

Huronian must be restricted to the upper or lower system; and if restricted to the upper system it remains attached to the best known and 

most characteristic portion of the old complex Huronian. For the older 

system, not distinctly named until 1886 as Keewatin by Lawson, the term 

Kewatian is proposed.

BELL,54 in L891, describes the geology of the district of Sudbury. The 

main outlines of the great Huronian area of this region are given. 

Within this region are many iuliers of gneiss and red quartz-syenite, 

which correspond with Laurentian types of rock, and it is uncertain 

whether they are protrusions of the older rocks from beneath or whether 

some of them may not be portions of the Huronian itself which have 

undergone further metamorphisni. In the Sudbury district many of 

the areas consist of separate masses, like large and small bowlders, the 

interspaces being filled by a 'breccia with a dioritic paste, and suggesting that these rocks may be underlain at no great depth by diorite 

which was in a soft condition after the gneiss and syenite had been consolidated. At some places within the syenite area, as, for example, 

about two miles west of C artier, a massive fine grained rock like some
44 PRE-CAMBRTAN ROCKS OF NORTH AMERICA. IBULL.SO.

varieties of graywacke may be seen passing into thoroughly crystalline 

quartz-syenite. The rocks in greatest quantity, and those which constitute the lowest member of the Huronian series between lakes Huron 

and Walmapitae, are quartzose graywackes and quartzites, with occasionally a little felsite. In this member of the series crystalline diorites 

occur as intruded masses, varying from a half a mile to ten miles in 

length. Also are associated obscurely stratified varieties of quartzdiorite and of dioritic and hornblendic schists, and also compact brownweathering dolomite. The next member of the series in ascending order 

is a black volcanic glass breccia consisting of angular fragments crowded 

together. The highest rocks of the series, or those which occupy the 

center of the trough, are evenly bedded argillaceous sandstones or graywackes, interstratified with slaty belts and overlain at the summit by 

black slates. The stratified Huronian rocks, as well as the gneiss and 

quartz-syenite, are traversed by dikes of coarsely crystalline diabase, 

which are often large and can be traced for considerable distances.

WINCHELL (N. H.),55 in 1891, gives further observations upon the Huronian. Northwest of Sudbury and eastward from Algoina there are 

two formations. In both, the slate and slate conglomerate constitute 

the upper formation. In the Sudbury region the underlying rocks are 

largely felsitic, but are also occasionally micaceous and hornblendic. 

In the section eastward from Algoma the underlying formation seems 

to be the Mississagui quartzite, with interbedded green fissile schist, 

with mica-schist varying into hornblende-schist. Logan's Mississagui 

quartzite is supposed not to be Logan's lowest gray quartzite, but 

is probably a constituent part of the Keewatin. It is concluded that 

the observations confirm, or at least do not contravene, the conclusion 

that the Huronian system' of the Canadian reports embraces two or 

three formations, one of these the true Huronian, first described and 

mapped by Murray; another, the Keewatin of Lawson; and another, 

the series of crystalline schists styled the Vermilion series.

PUMPELLY and VAN HisE,56 in 1892, describe the relations of the Huronian and Laurentian and also give evidence for the divisibility of 

the Huronian into two series as advocated by Winchell.

In reference to the latter point, at a limestone quarry about 2 miles 

northeast of G-arden river, the upper slate conglomerate was found in 

actual contact with the limestone member. This conglomerate has a 

rough appearance of stratification and bears numerous fragments of 

limestone, many of them more than a foot in length and all in precisely 

the condition in which is now the original limestone. In this conglomerate are also numerous fragments of schist and granite. The line of 

contact could be traced only a short distance, and it appears to follow 

somewhat closely the lamination of the limestone. These relations 

clearly indicate that after the limestone was deposited, before the beginning of the time of the upper slate conglomerate, there was a considerable interval of erosion. The observations thus tend to confirm
VANHISE.] LAKE HURON TO LAKE TEMISCAMANG. . 45

WinchelPs conclusion that the Laurentian is divisible into two discordant series, the break occurring above the lower limestone. If this 

break shall prove to be general at this horizon, it places in the Lower 

Huronian, using Logan's thicknesses for the formations,'about 5,000 

feet, and in the Upper Huronian about 13,000 feet.

Almost immediately below the limestone was found the lower slate 

conglomerate, which in lithological character is precisely like the slate 

conglomerate in contact with the granite below described.

As bearing upon the relations of the Huronian and Laurentian, one 

new locality was found, and the contact described by Irving east of 

Thessalon was again examined. About two miles northwest of Garden 

river the lower slate conglomerate of Logan was traced downward into 

a finely laminated seinierystalline quartzose schist, and this downward 

into a basal conglomerate and recomposed granite which rests almost 

directly upon the solid granite. The major part of the debris of the 

basal bowlder conglomerate is derived from the immediately subjacent 

granite. The evidence of erosive unconformability is thus of the clearest character. The likeness of the slate conglomerate at this locality 

to that below the limestone, the metamorphosed character of the 

Cjnartzose schist and the steepness of the inclination of the rocks all 

bear toward the correctness of Logan's mapping, that this slate conglomerate is the lower one, and, if so, the unconformable contact is 

between the lower series of the Huronian and the granite.

At the contact between the lower quartzite of Logan and the Laurentian east of Thessalon, described by Irving, it was found that the 

relations could be much more clearly seen than at the time the locality 

was visited by Irving, because the water was very low, and two islands 

upon which the contact occurs were then submerged. The Laurentian 

area does not consist of simply granite or gneiss, as might be inferred 

from Logan's mapping, but is an intricate complex of granite, gneiss, and 

schist. The granite has intruded the schist and fine grained gneisses in 

the most intricate manner. In many places large roundish fragments 

of schist or gneiss are contained in granite, and these have a decidedly 

water-worn appearance. However, in any given area the fragments 

are always of material identical with that of the immediate adjacent 

gneiss or schist. In short, the rocks furnish one of the most beautiful 

illustrations of the relations described by Lawson between schists and 

gneisses and a later intrusive granite. Eestiug upon this complex 

was found a great bowlder conglomerate which differs radically in 

its character from the pseudo-conglomerates of the Laurentian. The 

pebbles and bowlders instead of being widely separated are packed 

closely together. Within a very small area, a square yard or square 

rod, may be found all varieties of the material to be found within the 

basement complex: that is, many phases of crystalline schist, gneiss, 

granite, and granite-gneiss. On one of the islands in which the contact 

was seen, the line of separation is perfectly sharp and irregular, bend-
46 PRE-CAMBRIAN EOCKS OF NORTH AMERICA. [BULL. 80.

iiig at one place at an angle of 50°. Also the foliation of the granitegneisses abuts almost at right angles against the line of contact at one 

place. The contact here, then, has all the characteristics of one of erosive 

unconformability. Upon the second island, instead of a clear line of 

contact between the conglomerate and the basement complex there is 

an apparent gradation, the change occurring within 5 or 6 feet. Here 

the solid granite-gneiss is first broken; then in passing upward the angular fragments have moved somewhat; in passing still farther upward 

they become roundish and are mingled with extraneous material, until 

a bowlder conglomerate is reached which is in every respect like that 

before described. This relation is not uncommon wlien an encroaching 

shore-line overrides a rock formation.

It is concluded that between the lowest members of the Original 

Hnronian series and the granite-gneiss-schist basement complex which 

Logan has called Laurentian, there is the clearest evidence of a very 

great unconformity. Also, that the Laureutian series, instead of being 

a simple one, consists of rocks of many different kinds and has a most 

complex history.

SUMMARY OF 11ESULTS.

Bigsby's Transition formation is that to which the term Hnronian was 

later applied by Logan and Murray, and his description of this series 

is hence the earliest. From the first it is plain that Murray does not 

consider the series as metamorphic, since it is excluded from the rocks 

to which that term is applied. It is also plain that the true nature of 

the interbedded green stones was appreciated, Logan was distinctly a 

stratigraphical geologist, Avho believed in extreme metamorphism. of 

sedimentary beds, yet he also clearly saw that the greenstones associated with the fraginental rocks could not be regarded as other than 

of igneous origin.

As to the relations of the Huronian and Laurentian north of lake 

Huron, Murray made the distinction in 185.7 to rest upon age and upon 

lithological characteristics, the Laurentian being older and more completely crystalline than, the Huronian. While the Huronian and Laurentian by Logan and-Murray are. not described at any definite locality 

as having unconformable relations, the former states that the Huronian is a stratified series and reposes discordantly upon the Laurentian system, and in 1858 he again clearly indicates the same thing by 

the statement that in the slate conglomerates are bowlders and pebbles derived from the subjacent gneiss and that the lower formation 

was consequently converted into gneiss and probably greatly disturbed 

before the upper series was laid down. In 1865, Logan further says 

that the Huronian unconformably overlies the lower Laurentian, and 

is believed, although'not found in contact with it, to be more recent 

than the upper Laurentian. These statements are emphasized by his 

sections published in 1863, which represent the Uurouiau as resting 

unconformably upon the Laurentian. The first to describe an actual 

contact between the underlying gneissic series and the overlying Huro-
VANHISE.] LAKE HUEON TO LAKE TEMISCAMANG. . 47

nian was living, who in 1887 clearly showed that such an unconformity 

 \occurs. The observations of Putnpelly and myself reenforce this conclusion and show that between the lowest member of the Huronian and 

Laurentian complex is a very great discordance.

The facts given by Barlow, taken in connection with the foregoing, 

show tliat he has neglected to differentiate the clastic rocks of the 

Huron iau, from the more ancient underlying crystalline gneisses. Also, 

he has failed to separate an earlier granite-gneiss from a later intrusive. 

That a part of the granite is eruptive, of later age than the Huronian, 

was as well known to Logan and. Murray as to Barlow. These early 

geologists recognized both a later granite and a granite-gneiss basement 

complex upon which the Huronian was deposited, while the -latter 

failed to make this fundamental discrimination. He saw the former 

and assumed that this covered the entire ground.

As to the position taken by Alexander Winchell, that the Original 

Huronian is divisible into two unconformable series, it may be 

remarked that the locality in which the strongest evidence for this is 

given, Echo lake, is on the outskirts of the area mapped in detail by 

Logan and Murray. Before accepting the conclusion that these geologists, in their careful work extending over several years in the area of 

the Original Huroniau, have overlooked a great unconformity and have 

misunderstood what part of the area is covered by lower slate conglomerate and what by upper slate conglomerate, we ought to have the 

most decisive evidence. However, the observations of Pumpelly and 

myself tend toward the correctness of WinchelFs first conclusion. At 

least between the limestone and the upper slate conglomerate, in places, 

there has been a considerable erosion interval. That with the Huronian 

in the more general work of later years Logan and Murray placed two 

discordant series is certain. The same was done by the geologists on 

the south shore of lake Superior, and in view of this very common reference it is stated in another place that for these two series the terms 

Upper Huronian and Lower Huronian are used. If it is really the case 

that in the Original Huronian of the north channel of lake Huron, in 

the area covered by the detailed map of 1863, two discordant series do 

exist, this suggestion is eminently appropriate.

Great indisputable results were reached by the early Canadian 

geologists, Logan and Murray. This district north of lake Huron was 

the first in which it was shown that an unmistakable detrital and 

little metamorphosed series of rocks rests unconformably under the 

upper Cambrian. Also it was shown that this series is of such a character that the ordinary stratigraphical methods apply, and Logan and 

Murray were able to subdivide it into formations upon a lithological 

basis in the same fashion as is done in fossiliferous series. This is so 

evident that it would not be emphasized if it had not been denied. 

Far more to the credit of Logan and Murray is the recognition of the 

character of the amygdaloids and the interbedded greenstones. No 

extreme metamorphic theory was applied to them, and they were dis-
48 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

tinctly regarded as an exception to the ordinary stratigraphical lawu 

and separated both in descriptions and mapping. This' is the more 

creditable because for many years afterwards similar rocks were sup-- 

posed by many other writers to be parts of the stratified successions in" 

a completely metamorphosed condition had caused them to become 

crystalline. Finally it was recognized that this Huronian series rests 

unconformably upon an older gneissic and granitic crystalline series, 

which has yielded abundant fragments to the overlying rocks.

To the person who hypothecates that all pre-Cambrian rocks are 

wholly crystalline and that all truly detrital rocks are Cambrian or 

post-Cambrian, these conclusions prove only that inferior to the Potsdam sandstone, and separated from it by a great unconformity, is a 

series of rocks of great thickness, having a number of persistent members of varying lithological character, which are lower Cambrian. But 

this position does not lessen the value of the work done; for it would 

still be true that the Huronian series was the first so low in the geological column in which the above facts were shown.

The only rocks in the Original Huronian area which Logan correlated 

with tho:?e of the Original Laurentian area are the unconformably underlying granitic and gneissic series. These were called lower Laurentian, 

the idea being evidently to correlate them with the lower noncalcareous, 

division of the Original Laurentian. This correlation was plainly made 

on the ground of lithological likeness. That the Huronian is more 

recent than the upper T/aurentian was stated only as a belief. This 

belief appears to have been based upon the "nonmetamorphic" character of the Huronian as compared with the upper Laurentian. It is 

also possible that the fact that there is a structural break on the north 

shore of lake Huron, between the Huronian and the gneissic series, 

whereas no such break was found between the upper and lower divisions of the Original Laurentian, had an influence in leading to this 

conclusion.

NOTES.

The following are the titles of papers and works cited in the foregoing chapter, reference marks to which appear in the text:

1 On the Geology of the Ottawa and some of its Tributaries, W. E. Logan. Rept. of 

Prog. Geol. Survey of Canada for 1845-'46, pp. 40-51.

3 On the Geology of the Counties of Beauharnois and tho Lake of Two Mountains, 

W. E. Logan. Rept. of Prog. Geol. Survey of Canada for 1851-'52.

3 On the Geology of the Region between the Ottawa, the St. Lawrence, and the 

Rideau, Alexander Murray. Ibid., pp. 59-65.

4 W. E. Logan: Rept. of Prog. Geol. Survey of Canada for 1852-'53, pp. 8, 74. 

6 On the Geology of the Region between Kingston and Lake Sirncoe, Alexander 

Murray. Ibid., pp. 75-133.

6 On the Laurentian rocks of Grenville, Chatham, St. Jerome, etc., and the Economic Materials found in them, W. E. Logan. Rept. of Prog. Geol. Survey of Canada 

for 1853-'54-'55-'56, pp. 5-57. Accompanied by a sketch map.

7 On the Topographical and Geological Features of the Region between the Ottawa river and Georgian Bay, as well as North of Lake Huron, Alexander Murray, 

Ibid., pp. 59-190. Accompanied by two maps.
.ANHISB.] NOTES. 49

8 Reports of T. Sterry Hunt. Ib'id., pp. 397-494.

9 On the Probable Subdivision of the Laurentian Series of Rocks of Canada, Sir

~l.liam E. Logan. Proc. Am. Assoc. Adv. Sci., part 2, 1857, llth meeting, pp. 47-51.

1& 0n the Distribution of the Laurentian Limestones, and of the Drift in the Grenville Region, W. E. Logan. Rept. of Prog. Geol. Survey of Canada for 1858, pp. 8-40.

11 Contribution to the History of the Laurentian Limestones, Sir William E. Logan. 

Proc. Am. Assoc. Adv. Sci., 1859, 13th meeting, pp. 310-312.

12 Report of Progress of the Geological Survey of Canada from its Commencement 

to 1863, W. E. Logan, pp. 983. Accompanied by an atlas.

13 On the Laurentian Formation, its Mineral Constitution, its Geographical Distribution, and its Residuary Elements of Life, J. J. Bigsby. Geol. Magazine, 1864, vol. 

I, pp. 154-158, 200-206.

14 On the Geology and Economic Minerals of portions of the County of Hastings, 

Thomas Macfarlane. Rept. of Prog. Geol. Survey of Canada for 1863 to 1866, pp. 91-96.

15 Summary Report of Geological Investigations, W. E. Logan. Ibid., pp. 10-19.

16 On New Specimens of Eozoon, W. E. Logan. Quart. Jour. Geol. Soc., London, 

vol. xxm, 1867, pp. 253-256.

J7 Ascending Section of Laurentian Rocks in the County of Hastings, Canada West, 

H. G. Vennor. Ibid., pp. 256-257.

18 On the Graphite of the Laurentian of Canada, J. W. Dawson. Ibid., vol. xxv, 

1869, p. 406. See also vol. xxvi, pp. 112-117.

19 On the Geology of portions of Hastings, Peterborough, and Frontenac Counties, 

Ontario, Henry G. Vennor. Rept. of Prog. Geol. Survey of Canada from 1866 to 1869, 

pp. 143-171. Accompanied by a geological map.

20 Abstract of a Report on the Geology of parts of the Counties of Frontenac, Leeds, 

and Lanark (Ontario), Henry G. Vennor. Rept. of Prog. Geol. Survey of Canada for 

1870-;71, pp. 309-315.

21 Progress Report of Exploration and Survey of Leeds, Frontenac, and Lanark, 

Henry G. Vennor. Rept. of Prog. Geol. Survey of Canada for 1871-'72, pp. 120-140.

33 On Explorations and Surveys in the Counties of Frontenac, Leeds, and Lanark, 

Henry G. Vennor. Rept. of Prog. Geol. Survey of Canada, 1872-'73, pp. 136-179.

23 Report of Explorations and Surveys in Frontenac, Leeds, and Lanark Counties, 

Henry G. Vennor. Rept. of Prog. Geol. Survey of Canada for 1873-74, pp. 103-146.

 24 Progress Report of Explorations and Surveys in the rear portions of Frontenac, 

and Lanark Counties, Henry G. Vennor. Rept. of Prog. Geol. Survey of Canada for 

1874-'75, pp. 105-165. Accompanied by a map; see also Rept. of Prog. Geol. Survey 

of Canada, 1875-'76, p. 4.

26 Archean of Canada, Henry G. Vennor. Am. Jour. Sci., 3d ser., vol. xiv, 1877, pp. 

313-316.

26 Progress Report of Explorations and Surveys made during the years 1875 and 

1876 in the counties of Renfrew, Pontiac, and Ottawa, Henry G. Veiinor. Rept. of 

Prog. Geol. Survey of Canada for 1876-'77, pp. 244-320. Accompanied by a map.

27 Report on Geological Researches North of Lake Huron and East of Lake Superior, 

Robert Bell. Ibid., pp. 193-220.

28 Notes upon the Occurrence of Eozoic rocks in the South Riding of Hastings 

County, and in Prince Edward County, Ontario, D. F. H. Wilkins. Can. Nat., 2cl. ser. 

vol. vin, pp. 278-282.

29 Report of Observations on the Stratigraphy of the Quebec Group and the Older 

Crystalline Rocks of Canada, A. R. C. Selwyn. Rept. of Prog. Geol. Survey of Canada 

for 1877-'78, pp. 1-15 A. See also Summary report of the operations of the Geological 

Corps to December, 1880. Rept. of Prog. Geol. and Nat. Hist. Survey of Canada for 

1879-'80, pp. 1-9.

30 Descriptive Sketcb\>f the Physical Geography and Geology of the Dominion of 

Canada, Alfred R. C. Selwyn and G. M. Davvsou, pp. 55. 

Bull. 86 4
50 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

31 Geological and Mineralogical Observations ou the Northwest portion of Lake 

Huron, John J. Bigsby. Am. Jour. Sci., 1st ser., vol. in, 1821, pp. 245-272.

32 Report on the District lying in a general line from Georgian Bay on Lake Huron, 

and the lower extremity of Lake Erie, Alexander Murray. Rept. of Prog. Geol. Survey of Canada for 1842->43, pp. 16-17.

33 Report of W. E. Logan. Rept. of Prog. Geol. Survey of Canada for 1845-'46, pp. 98.

34 Report of Observations made in the Survey of the Upper Peninsula of Michigan, 

John Locke. Executive Docs., 1st sess. 30th Cong., No. 2, vol. n, 1847-'48, pp. 183-199.

35 Report of an Exploration of Several Points on the St. Marys River, William F. 

Channing. Ibid., pp. 199-209.

38 On the North Coast of Lake Huron, Alexander Murray. Rept. of Prog. Geol. Survey of Canada for 1847-'48, pp. 93-124.

37 Report of the Geological Survey of Canada on the North Shore of Lake Huron, 

W. E. Logan, 1849, pp. 8-20.

38 On the Geology of parts of the Coast of Lake Huron, the Spanish River, etc., Alexander Murray. Rept. of Prog. Geol. Survey of Canada for 1848-'49, pp. 7-46.

39 On the Footprints occurring in the Potsdam Sandstone of Canada, W. E. LoganQuart. Jour. Geol. Soc., London, vol. vm, 1852, pp. 199-213; with a geological map.

40 Remarks relating chiefly to the succeeding Reports, W. E. Logan. Rept. of Prog. 

Geol. Survey of Canada for 1857, pp. 1-12.'

41 On the Coast at the mouth of French River, Georgian Bay; on Echo Lake and its 

environs, and on the Limestone of Bruce Mines, Alexander Murray. Ibid., pp. 13-27; 

accompanied by a map.

42 On the Division of the Azoic rocks of Canada into Huronian and Lanrentian, Sir 

William E. Logan. Proc. Am. Assoc. Adv. Sci., llth meeting, part 2, 1857, pp. 44-47.

43 On the Country between the Thessalon River and Lake Huron, and between the 

Thessalon and Mississagui, Alexander Murray. Rept. of Prog. Geol. Survey of Canada 

for 1858, pp. 67-100; accompanied by a map and section.

44 On the Cambrian and Huronian Formations, J. J. Bigsby. Quart. Jour. Geol. Soc., 

London, vol. xix, 1863, pp. 36-52.

45 On the Occurrence of Organic Remains in the Laurbntian rocks of Canada, Sir W. 

E. Logan. Quart. Jour. Geol. Soc., London, vol. xxi, 1865, pp. 45-50.

46 Is there a Huronian Group ? R. D. Irving. Am. Jour. Sci., 3d ser., vol. xxxiv, 

1887, pp. 204-216,249-263,366-374.

47 The Original Huronian, N. H. Winchell. 16th Ann. Rept. Geol. and Nat. Hist. 

Survey of Minn. for 1887, pp. 12-40.

48 Observations in the Typical Huronian Region of Canada, Alexander Winchell. 

Ibid, pp. 145-171.

49 Notes on a part of the Huronian Series in the Neighborhood of Sudbury (Canada), 

T. G. Bonney. Quart. Jour. Geol. Soc., London, vol. XLIV, 1888, pp. 32-45.

60 On the Contact of the Huronian and Laurentian rocks North of Lake Huron, Alfred E. Barlow. Am. Geol., vol. vi, 1890, pp. 19-32.

51 The Origin of Gneiss and some other Primitive rocks, Robert Bell. Proc. Am. 

Assoc. Adv. Sci., 1889, 38th meeting, pp. 227-231.

62 Recent Observations on some Canadian rocks, Alexander Winchell. Am. Geol., 

vol. vi, 1890, pp. 360-370.

63 A Last Word with the Huronian, Alexander Winchell. Bull. Geol. Soc. America, 

vol. n, 1891, pp. 85-124.

54 The Nickel and Copper Deposits of Sudbury District, Canada, Robert Bell. Ibid., 

pp. 125-137.

56 Further observations on the Typical Huroniau, and on the rocks about Sudbury, 

Ontario. 18th Ann. Rept. Geol. and Nat. Hist. Survey of Minn. for 1889, pp. 47-59.

56 Observations upon the Structural Relations of the Uppe/Huronian, Lower Huro~ 

niau and Basement Complex on the North Shore of Lake Huron, Raphael Pumpelly 

and C. R. Van Hise. Am. Jour. Sci., 3d ser., vol. xun, 1892, pp. 224-232,
CHAPTER 11. 

LAKE SUPERIOR REGION.

SECTION I. WORK OF THE OFFICIAL GEOLOGISTS OF THE CANADIAN 

SURVEY AND ASSOCIATES.

BiGSBY, 1 in 1825, describes in detail the rocks at many points along 

the north shore of lake Superior, between, the falls of St. Mary and 

Grand Portage, an interval of 445 miles. The varieties of rocks are 

few in number when compared with a similar extent of country in 

Europe. Of mica-slate, clay-slate, etc., not a vestige was found, not even 

in de"bris, nor of any secondary deposits above the Mountain limestone. 

Sandstone, under various modifications, occupies the greatest space 5 

in intimate connection with tlienext prevailing rocks, the amygdaloids, 

porphyries, and greenstone trap. The alternating granites and greenstones of the northeastern and eastern coasts are nearly equal in quantity to these. The granites and syenites are not stratified. The porphyry, amygdaloid, and sandstone are considered contemporaneous and 

newer than the granites, although not much, as indicated by the transitions and alternations occurring about Gargantua. The age and connections of the greenstone trap the author is not prepared to state. 

The sandstone is most probably Old Eed, a conclusion reached from the 

materials composing it, and its direct superposition on inclined rocks in 

this and other great lakes of the St. Lawrence and because it supports 

a fossiliferous limestone full of product*, turbinolioe, earyophyllire, 

trilobites, conularise, encrmites, and orthoceratites, etc. The granite 

and syenite seem to be of the same age and belong to'the transition or 

to the youngest of the primitive.

On the old route from lake Superior to the lake of the Woods (for 

430 miles) is an alternation of chloritic greenstone and amphibolitic 

granite, but at and toward the lake of the Woods the greenstone 

passes into gneiss, and mica-slate, traversed in many ways and in great 

quantities by graphic granite.

BAYFiELD,2 in 1829, gives an outline of the geology of lake Superior. 

The rocks of the lake are divided into four divisions: First, the inferior 

order, comprising granites, which almost always contain more or less 

hornblende. In this division neither gneiss nor mica-slate was met 

with, although the granite by the abundance of its mica or lamellar 

structure may for a short distance assume the appearance, of either. 

Second, the subrnedial order, which includes greenstones, common 

jaspery variety of greenstone slates, flinty chlorite, talcose slate, and in

51
52 PKE-CAMBRIAN BOOKS OF NORTH AMERICA. [BULL. 88.

one place alone transition limestone, with perhaps traces of gray wacke. 

Third, trap or overlying rock, the most of which is amygdaloid; various 

kinds of porphyry are next in quantity; then trap, greenstone, syenites, 

and pitchstone. Fourth, the medial order, the only rock of which is 

the Old Eed sandstone. Then follows an account of the distribution 

'of each of these orders. The amygdaloid with little doubt rests upon 

the syenite and granite, although the junction was never seen. The 

amygdaloid passes into greenstone on the one hand simply by being 

divested of its nodules, and into porphyry on the other. The Old Eed 

sandstone may be traced from one extremity of the lake to the other. 

Its existence is noticed on both shores, and it is traced across the lake 

by many of the islands, so as to leave no doubt of its being a general 

formation throughout the whole of the basin of lake Superior. It is 

generally horizontally stratified or nearly so. There are many instances 

of the conjunction of the sandstone and granite, which serve.to prove 

that the sandstone was deposited after the granite occupied its present 

position. The sandstone, when conglomeratic, as Is very frequently 

the case, contains fragments of the trap as well as of the inferior order, 

which are rounded by attrition, and it is» therefore plain that the sandStone is later than the trap rocks. Organic remains were sought in 

this rock, but never discovered. It is placed as the Old Red because 

of its position immediately on the granite, its structure, and component 

parts.

BAYFIELD,3 in 1845, places with the Primary rocks most of the elastics on the north shore of lake Superior. These are cut by various 

greenstones. A red sandstone forms nearly the entire southern boundary of the lake. In places it is shattered by the upheaval of granite 

and by trap rocks which enter into the composition of its conglomerates. At Mpigon bay it is overlaid by an immense bed of greenstone. 

It is probable, although not certain, that this sandstone underlies the 

fossiliferous red sandstone of St. Marys.

LoGrAN,4 in 1847, in a report on the geology and economic minerals of 

lake Superior, gives an account of a rather detailed examination of the 

north shore of lake Superior from Pigeon river to Sault Ste. Marie. 

Michipicoten island was also examined. Lake Superior appears to be 

set in a geological depression, which presents formations of a similar 

character on both the north and south sides, dipping to the center. 

The series on the north, in ascending order, consists of the following: 

(1) Granite and syenite; (2) gneiss; (3) chloritic and partially talcose 

and conglomerate slates; (4) bluish slates or shales, interstratified with 

trap; (5) sandstones, limestones, indurated marls, and conglomerates, 

interstratified with trap. The gneiss is succeeded by dark green slates, 

which at the base appear to be occasionally interstratified with beds of 

the subjacent granite and gneiss. These slaty beds at times have the 

quality of a greenstone, at times a mica-slate, and a few are quartz 

rocks. Higher in the series are conglomerates, the pebbles of which
U.S. GEOLOGICAL SURVEY

a'H.i " ^=»-'> ll-'''^-? ' (_. t.^J^i \ ^ 5"-F^/-, _j^ SgM/r ^"--4i fegr*T?>;jt ^Jl

.TAN

HiirpiiiaKevveenawan 

["Ah"" r Ak 1

POST ALKONKIAX

GEOLOG1CAI, MAP OF 'AKE SUPEKIOR KEGIOX

SHOWING PRE-CAMBKD CRYSTALLINE ROCKS.

Compiled I'rornOtficia.S.nnA (Canadian Surveys.

HURONIAN

) 

2 T3 T

I 4 

5 

6 T

h7 h s h9 tilO 

A h II F
VANHISE.] LAKE SUPERIOR REGION. 53

are all apparently from hypogene rocks. Formations 4 and 5 rest unconformably upon 1, 2, and 3, having sometimes basal conglomerates, 

the pebbles being of quartz, red jasper, and slate. The upper part of 

3 strongly resembles the upper slates at lake Temiscamang. The succession of conglomerate and pebbly slates at Gros cap has a total 

thickness of 1,700 feet. In group 5 are the succession of rocks at 

Michipicoten island, a portion of those at Thunder bay,, and at other 

localities. At Michipicoten the thickness of the interbedded volcanics 

and water-deposited elastics is not less than 10,000 or 12,000 feet. 

Group i> exhibits an unconformity to the granite. The conclusion that 

the copper-bearing series is older than the Potsdam sandstone arrived 

at by Houghton in 1841, is thought to be probably true.

MURRAY,5 in 1847, in an account of the Kaministiquia and Michipicoten rivers, divides the geological formation into three groups: (1) 

Granite, syenite, gneiss, micaceous and chloritic schist; (2) blackish 

argillaceous slates, with associated trap; (3) drift clays and sands. At 

the portage of the Kaministiquia a massive syenite passes into a gneissoid syenite, upon which rest conformably dark colored altered slates, 

one rock passing imperceptibly into the other. The junction of 1 and 2 

was not observed.

LOG-AN,6 in 1852, finds the rocks of the north shore of lake Superior 

to have the following succession: Granite, syenite, and gneiss, or micaceous and hornblende-gneiss, which are succeeded by chloritic and 

talcose slates, interstratified with obscure conglomerates with a slaty 

base. Upon these rest unconformably bluish slates., with belts of chert 

and limestone toward the bottom, and thick flows of greenstone trap at 

the top. Above these are alternations of sandstones, conglomerates, 

ainygdaloids and traps, the whole thickness of the upper series above 

the unconformity being not less than 12,000 feet. The conclusion is 

reached that this upper series is the equivalent of the Potsdam sandstone, which rests unconformably upon the tilted beds of the lake 

Huron series, and that both are contemporaneous with the Cambrian 

series of the British isles.

BiGSBY,7 in 1852, finds the crystalline strata of the lake of the Woods 

to conform in strike with those several hundred miles southward on 

the river Mississippi. Granite occupies the axis in the northeast part 

of the lake of the Woods, and is always the lowest rock, the gneiss, 

mica-schist and greenstone dipping away from it on both sides. Greenstone is perhaps the most abundant rock in this part of the lake, and 

greenstone conglomerates are found which contain black masses of 

greenstone lying with their greater length parallel to the strike. The 

granites and mica-slates are intimately associated, and the granite includes greenstone in a thousand tortuous masses, tongues, and slender 

veins. Also the granite is cut by greenstone.

BiGSBY,8 in 1852, divides the rocks about lake Superior into (1) Metamorphic, including greenstone, slates, schists, gneisses, quartzites,
54 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

jaspers, and crystalline limestones; (2) aqueous, including the calciferous and Cambrian sandstones and conglomerates; (3) igneous, including granite, syenite, and trap. The lake is a trough or basin of Cambrian or Silurian sandstone, surrounded by two irregular and imperfect 

zones, the inner consisting of traps with conglomerates, the outer, of 

metaniorphic, flanked by igneous rocks. The metamorphic rocks, with 

the exception of quartzite and jasper, the oldest in the lake, support 

unconformably the sandstone. These rocks have been upheaved and 

altered by the intrusion of igneous rocks. The sandstone is generally 

horizontal, except near the intrusive rocks, where it rises a^ high 

angles and passes into jasper, porphyry, gneiss, or quartzite. The conglomerate is of the same age as much of the sandstone, and is between 

it and the trap; and there is reason to believe that the sandstone is 

interleaved with trap. The igneous rock, granite, everywhere forms 

the nucleus of the anticlinal axes. The trap rocks are divided into 

crystalline mountain masses sometimes anticlinal and syenitic; into 

bedded traps; and into dikes intersecting igneous and metamorphic 

rocks; but all are portions of one long series of volcanic operations.

BIGSBY, 9 in 1854, finds the geology of Eainy lake to be as follows: 

Chloritic and greenstone slates, gneiss and mica-slate, in proportional 

quantities in the order here set down, seem, once to have occupied the 

lake basin, with an ENE. strike, and a NNW. dip, at a high angle 

usually. But subsequently a very extensive outburst of granite, with 

some syenite, has taken place, to the great disturbance of the stratified 

rocks, and penetrating them both in intercalations and crosswise. 

These intrusive rocks occupy a very large portion of the lake, most of 

the western shore, nearly all the eastern trough or arm, and much of 

the east end of the lake about Stokes and Hale bays. Intercalations 

of syenite and hornblende-greenstone are frequent, and so is the occurrence of veins of porphyritic granite traversing the gneiss in all directions. The chlorite-slate greenstone, gneiss, and mica-slate are conformable with each other.

DAWSON (Sm WILLIAM), in 1857, finds between Sault Ste. Marie 

and Mamainse three of the oldest formations in America or the world. 

Beginning at the top are: (1) Potsdam sandstone; (2) an enormously 

thick formation of conglomerates, sandstones, slate, and trap, constituting the Huronian series of Logan; (3) a still older Laurentian series, 

represented here principally by syenitic rocks which have afforded the 

material of the Huronian conglomerates. The sandstones and conglomerates of the second series probably unconforma.bly underlie the 

Potsdam sandstone, as is indicated by their high inclination and disturbed condition.

LOGAN, u in 1863, finds on the north shore of lake Superior crystalline stratified rocks which occur in extensive tracts about Eainy lake 

and lac la Croix, as well as adjacent to lake Superior, which are probably 

of Laurentian age. There are three areas of Huronian along the
VANSISE.] LAKE SUPERIOR REGION. 55

northeast coast of lake Superior, and a narrow strip of Huronian rocks 

are seen along Thunder bay.

The Laurentian gneiss is succeeded by green or gray slates, which at 

the base appear to be hiterstratified with feldspathic beds of the reddish color belonging to the subjacent gneiss. Rising in the series the 

dark green slates become interstratined with layers holding a sufficient 

number of pebbles of different kinds to constitute conglomerates. It 

often happens, unless the pebbles are of white quartz, that they are 

very obscurely distinguishable on fracturing the rock, both the pebbles 

and the matrix having a gray color, and showing very little apparent 

difference in mineral character.

The Dor6 section, composed of strata inclined only 10° or 15° from 

the vertical, 1,700 feet thick, consists mainly of green slate rock and a 

green slate conglomerate^ the pebbles being of granite, gneiss, syenite, 

etc., and some of the bowlders of which are a foot in diameter. At the 

Dore" the lower part of the section assumes more the character of a 

gneiss and becomes interstratined with feldspathic layers. The Laurentian appears to be conformable with and to grade into the Huronian 

on the Kaministiquia river.

The Huronian formation of lake Superior is unconformably overlain 

by a second series of copper-bearing rocks, which may conveniently be 

divided into two groups, the lower consisting of bluish slates or shales, 

interstratined with chert beds, sandstones and trap, and the upper consisting of a succession of sandstones, limestones, marls, and conglomerates, also interstratined with trap which is often arnygdaloidal. At 

the top of the lower group is a crowning overflow of trap 200 or 300 

feet thick and the whole of it has a thickness of 1,500 or 2,000 feet. 

The upper group contains a great quantity of trap layers and has an 

enormous trappean overflow, the total volume having a thickness of 

between 6,000 and 10,000 feet. Dike rocks, consisting of greenstone, 

porphyry, and syenite, are found to be of two ages. The lower group 

composes the whole country, both islands and mainland, between Pigeon 

river and fort William. The upper group occupies the coast and islands 

from the south side of Thunder cape to the east end of Battle islands 

east of Mpigon bay. It also covers a large part of isle Eoyale and 

Michipicoten, at which latter island the total volume of the formation 

is at the most moderate estimation 12,000 feet. Upon the east coast of 

lake Superior this group is found at cape Ohoyye, cape Gargautua, 

point anx Mines, Mamainse, where the breadth across the measures is 

sufficient to give a thickness not far from 10,000, and at three other 

places on the coast between the last point and Sault Ste. Marie.

As to the age of this series, the fact that the generally moderate dips ot 

the red sandstone at Sault Ste. Marie contrasts with the higher inclinations of the copper-bearing- rocks, while none of the many dikes are 

known to intersect the Sault Ste. Marie sandstone, leads to the suspicion 

that the latter may overlie unconformably the rocks which, associated
56 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BOLL.86.

with the trap, constitute the copper-bearing series. The affinities of 

the Sault Ste» Marie red sandstone appear to bring it into the position 

of the Chazy rather than the' Potsdam formation, and, if this were established, the copper-bearing portion of .the lake Superior rocks might 

reasonably be considered to belong to the Calciferous and the Potsdam 

formations. . >

MACFAELANE, 12 in 1866, gives observations on the Laurentian, Huronian, and Upper Copper-bearing rocks of lake Superior. The Laurentian series on lake Superior seems to differ somewhat from other parts 

of Canada. The rocks are all highly crystalline, seldom thoroughly 

gneissoid, and all are unaccompanied by crystalline limestone, which is 

such a marked feature in some Laurentian districts. The gneiss strata 

are much contorted and are intersected with granite in almost equal 

quantity with the gneiss itself 5 and although this latter occurs in irregular veins, at the point of junction it is as firmly cemented with the 

gneiss as any two pieces of one and the same rock could well be. On 

the Goulais bay fragments of hornblende rock or schist up to 3 feet in 

diameter are inclosed in a coarse grained syenitic granite. In this series 

the oldest rock is the most basic in constitution, and this is the case 

without regard to mineralogical composition or structure of the rocks 

associated together. The indistinctness of parallelism in the rocks renders it a matter of extreme difficulty to form any clear ideas as to their 

succession, even if such should exist. Besides the above rocks there 

are considerable areas of granite, syenite, dolerite, diorite, and melaphyre found in the Laurentian.

The rocks of the Huronian system consist in large part of diabase, 

amygdaloid, diabase-schist, greenstone, breccias, and slaty greenstones. 

Interstratified with these are slate, slate conglomerate and quartzite. 

The bowlders and pebbles of the conglomerate of Dore" river are for the 

most part granite; they are elongated and flattened, the pebbles sometimes being scarcely distinguishable from the slate. Granitic veins or 

masses, like the Laurentiau, are found in the schistose greenstones, 

which are regarded as belonging to the Huronian. As to the succession of the strata, the author is as much at a loss among the irregular 

schistose Huronian greenstones as among the gneissoid granites of the 

Laurentian.

The Mamainse section of Upper Copper-bearing rocks consists of 

interbedded basic lava flows, often amygdaloidal, sandstones, and conglomerates, the total thickness being more than 16,000 feet. The total 

thickness of the series at Mamainse and Michipicoten is believed to be 

at least 20,000 feet. As to the relations of the horizontal Sault sandstone to the upper copper beaming series, a place was found on the south 

of point aux Mines where the Mamainse series adjoins the Laurentian 

rocks. The lowest member of the former is unconformably overlain by 

thin bedded bluish and yellowish gray sandstone, striking N. 50° E., 

and dipping 18° JsTW. The lowest layer is a conglomerate with granitic
VANHISE.] LAKE SUPERIOR REGION. 57

and trappean bowlders, and is followed by thin bedded sandstones, and 

these by thin shaly layers. ' 

MACFARLANE, 13 in 1868, describes the rocks of the north and east 

shore of lake Superior. He here finds four formations the Laurentian, 

Huronian, Upper Copper-bearing rocks, and St. Mary sandstone. The 

most prevalent rocks of the Laurentian series are of a massive crystalline character, more of a granitic than of a gneissic nature. Almost 

equally frequent with the granitic and gneissic rocks are aggregates of 

rocks which can be described as brecciated and intrusive, gneissic, 

granitic, and syenitic rocks. In these the order of age is always from 

basic to acidic. In one case fragments of hornblende-schists are found 

inclosed in syenitic granite, which is cut by granite dikes of different 

ages. It is believed that these rocks are wholly of igneous origin, representing a single period of time the basic rock first solidified; they 

were then rent off, broken up, and the crevices filled with more siliceous 

material, which gradually solidified, after which occurred another general movement with further intrusion of the most siliceous materials.

In the Huronian series is placed diabase, augite-porphyry, calcareous 

diabase, diabase schist, greenstone and greenstone slate, chlorite-schist, 

quartzite, hematite, greenstone breccia, and slate-conglomerate. The 

slate conglomerates frequently contains granite pebbles which are in 

roundish, lenticular, bent, long-drawn out masses, with a diabase-schist 

or greenstone-slate matrix. These rocks locally have a sedimentary 

appearance, but are believed to be due to the subsequent intrusion of the 

Huronian rocks, which have caught granite fragments in them, and, by 

movement and heat, have softened and much distorted the contained 

fragments. It follows that far the greater number of the Huronian 

rocks are regarded as purely igneous.

In the Upper Copper-bearing series are distinguished melaphyre of 

various kinds melaphyre breccia, porphyrite, porphyritic con glomerate, 

felsite-tuff, polygenous conglomerate, and sandstone. The polygenous 

conglomerate contains, at Mamainse, fragments chiefly of granite, gneiss, 

quartzite, greenstone and slate, while some of the newer contain abundant bowlders of melaphyre and amygdaloid. The igneous rocks and 

sandstones are regularly interstratified with each other. In many places 

the trap lies unconformably upon the upturned and contorted edges of 

the sandstone.

Along the coast and upon many islands is found an almost horizontal 

red sandstone, which is supposed to be a continuation of the Sault Ste. 

Marie sandstone. Its relations to the copper-bearing rocks are not 

clearly made out, but the lowest members of the Mamainse series, are 

unconformably overlain by sandstones which may be the equivalent of 

the horizontal red sandstones, but their lithological character is different. It is suggested, on lithological grounds, that this red sandstone 

may be of Permian age.
58 PRE-CAMBRXAN ROCKS OF NORTH AMERICA. [BULL.86.

MACFAELANE,14 in 1869, describes at Thunder cape a series of interstratified argillaceous and white and red dolomitic sandstones, which 

had been disturbed and eroded before the flow appeared which forms 

the summit rock of the cape*

BELL,IS in 1870, gives an account of the geology of the northwest 

coast of lake Superior and the Nipigon districts The copper-bearing 

rocks are divided into a lower group and an upper group, and each of 

these groups separated into several divisions, In the upper group only 

is found interbedded trap. Different portions Of this series are found 

overlying unconformably in certain places the Laurentian and in 

others the Huronian; and the great trap overflow which crowns Thun* 

der cape rests in various places unconformably upon different members of both the upper and lower groups of the Upper Copper-bearing 

series. On account of the great thickness of this series, the absence 

of fossils, the prevalence of marls and sandstones charged with red 

oxide of iron, and of basalts, amygdaloids, and trap rocks, and various 

zeolites and native copper, this series is considered as probably of 

Permian or Triassic age. Between the margin of the Upper Copper, 

bearing rocks on Thunder bay and the Laureutian range, all the country 

not occupied by the syenitic areas appear to be composed of rocks of 

the Huronian series, consisting of diorites, dioritic conglomerates, hornblendic and fine grained micaceous slates, with some quartzites.

BELL,IG in 1872, finds in the country north of lake Superior, between 

Mpigon and Michipicoten rivers, both Laurentiau and Huronian rocks. 

The former includes gneisses and granites, and the latter includes 

slates, conglomerates, massive and schistose diorites, fine grained 

gneisses, mica-schists, micaceous, hornblendic, chloritic, feldspathic 

and epidotic schists, slates, granites, and iron ore. The Huronian rocks 

dip in various directions. At White river hornblendic schist and light 

gray gneiss are interstratified with massive granitic gneiss, and similar 

schists appear to rest conformably upon massive gneisses for a long 

way north of the river.

BELL,17 in 1872, finds in the country between lake Superior and the 

Albany river areas of Laurentian and Huronian rocks. Between 

Mousewake lake and Martins falls bands of gneiss are inter stratified 

with the schists, and just at Martins falls the latter have'become entirely replaced by red and gray gneisses, apparently showing a conformable passage from the Huronian into the Laurentian rocks. A 

similar blending of these formations was noticed last year in the neighborhood of White lake.

SELWYN,18 in 1873, finds, between Mille Lacs and Separation lake and 

the lake of the Woods, a series of parallel bands of schistose and slaty 

layers where hitherto was supposed to be almost exclusively the 

Laurentian gneiss. The facts observed lead to the conclusion, as 

stated by Bell, that the two series are in conformable sequence; yet it 

is far from improbable that this apparent conformity is only local and
VANHISE.] LAKE SUPERIOR REGION. - 59

that a more extended and detailed investigation of the structure would 

show that there is in reality a very considerable break between the 

Laurentian gneiss and the overlying schistose and slaty strata referred 

to the Huronian rocks, The evidence as to the age of these latter is 

not satisfactory. They resemble as closely the altered rocks of the 

Quebec group as they do the Huronian of lake Huron and Superior.

BELL, 19 in 1873, finds in the country between lake Superior and lake 

Winnipeg rocks belonging to the Laurentian, Huronian, and Upper 

Copper-bearing series. The southern shores of lake of Mille Lacs are 

composed of Huronian strata. The Laurentian gneiss and Huronian 

schists at many places alternate with each other. The junction of the 

Laurentian rocks on the north with the Huronian schists on the south 

occurs at Eat portage on the lake of the Woods. The two rocks are 

seen almost in contact with each other and have the same strike and 

dip. The rocks classified as Huronian consist principally of a great 

variety of crystalline schists in which a greenish color prevails. In 

addition to these are grayish quartzites and schists, sometimes with 

iron ore, diorites, imperfect gneisses. The areas of granite and syenite 

in the region, which vary from patches to areas many miles in length, 

are always more or less intimately connected with the Huronian bauds. 

The distinction between the Laurentian and Huronian rocks is chiefly 

of a lithological character, the Huronian appearing to succeed the 

Laurentian conformably. The Upper Copper-bearing series, composed 

of slates, marls, sandstones, and traps, lie nearly horizontally on the 

edges of the Laurentian and Huronian rocks.

HUNT,20 in 1873, applies the name Animikie group to the lower division of Logan's Upper Copper-bearing series of lake Superior as it occurs 

at Thunder bay, where it includes dark colored argillites and sandstones 

.overlain with a slight discordance by red and white sandstones apparently the same as those of the Keweenaw district. The dark colored 

sediments of the Animikie group rest directly upon the edges of the 

crystalline Huronian schists and are cut by great dikes of diorite. The, 

great Keweenaw group, with its cupriferous amygdaloids, is here absent, 

although met with a few miles to the eastward. This group, as shown 

by Brooks and Pumpelly, occupies a place between the Huronian schists 

and the nearly horizontal red and white sandstone of the region, which 

is itself below the Trenton limestone.

BELL,21 in 1874, in the country between the Eed river and the South 

Saskatchewan, finds extensively mica-schists and gneisses; but a broad 

band of schist, having the character of the Huronian formation, crosses 

the central part of Eainy lake. On the islands of the lake of the Woods 

the granites, gneisses, and Huronian schists are intricately mingled with 

each other.

DAWSON (G-. M.)22, in 1875, gives an account of the geology of the lake 

of the Woods, where the rocks are wholly Laurentian and Huronian. 

The Laurentian formation is represented by a great thickness of granit-
60 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [Buu,.86.

oid and thick-bedded gneisses, which pass upward into thin-bedded 

gneisses and highly crystalline micaceous and hornblendic schists.

The Huronian rocks are more variable in character. The lowest beds 

are, for the most part, hard green rocks, with little traces of stratification, but hold some well stratified micaceous and chloritic schists and 

also imperfect gneiss. On these rest a great thickness of massive beds 

characterized by the predominance of conglomerate, but including 

quartzites and dioritic rocks. Above these is an extensive series of 

schistose and slaty beds generally more or less nacreous and chloritic 

or talcose, but often hornblendic and micaceous. They inclose also conglomerates, quartzites, and diorite beds. It is believed two movements 

have conspired to form the present features of the region, both being 

post-Huronian. The first of these is connected with the post-Huronian 

granite eruptions j the second and more important is believed to have 

taken place later, and to it is supposed to be due the parallelism in the 

folding of the Laurentian and Huronian rocks. At Eat portage the 

junction of the Laurentian and Huronian is so sharply defined that the 

hand can be laid upon it. This sharp contact is believed to be due to 

faulting. Adjacent to the granite the Huronian slate series is metamorphosed, and the occasional gneissic aspect of the Huronian is attributed to the granitic intrusions. The large Y-shaped granite mass in the 

northwest angle, in contact with the altered sedimentary rocks, assumes 

a more basic character and a darker aspect, becoming blackish gneissic 

diorite and gray syenitic diorite. The conglomerate beds are of immense 

thickness and could perhaps be best described as slate conglomerates. 

The pebbles generally resemble the matrix, and best appear upon a 

weathered surface; for pn a freshly broken surface no clear distinction 

appears between the fragments and the inclosing materials, and the 

rock differs from the more compact altered schists and slates only in its 

rougher surface of fracture and a somewhat spotted character. The 

greenstone conglomerates of Bigsby resemble roughly fractured pieces 

of diorite in a dioritic paste. The quartzites show a tendency to run 

into conglomerates, and certain of the conglomerates have an aspect of 

a volcanic breccia. There is an entire absence of any granitic or gneissic 

beds in the conglomerates and breccias, and in this respect these Huronian rocks differ from the typical area. It is suggested that ,this fact 

may mean that the formation of the whole Huronian series took place 

subsequent to that of the typical Huronian, and therefore are perhaps 

more nearly equivalent to those of the Quebec group. The granitoid 

gneisses and intrusive granites are universally cut by veins of red 

orthoclase feldspar associated with quartz; and basic diorite dikes cut 

both the granitic and altered Laurentian rocks.

BELL,23 in 1875, describes on the north shore of lake Superior the 

Laurentian, Huronian, and Upper Copper-bearing rocks. The Huronian occupies a large extent of country, alternating with bands of Laurentian, on both the north and south shores of the lake. North of lake
VA.NHISE.] LAKE SUPERIOR REGION. 61

Superior the Laurentian rocks consist for the most part of gray and reddish gneiss, with micaceous belts and mica-schists. In the same region 

the Huronian rocks are mostly of a schistose character, the most common of which are greenish schists and imperfect gneisses, which include 

micaceous, hornblendic, dioritic, porphyritic, siliceous, cherty, chloritic, 

felsitic, and argillaceous schists; more rarely dolomitic schists, and 

occasionally bands of magnetic iron ore and hematite. Connected with 

the Huronian rocks are various patches of granite and syenite which 

show no stratification. In the Mpigon basin the Upper Copper-bearing rocks have their maximum development in Canadian territory. The 

basin consists of marls, sandstones, often covered with trappean outflows. For this Upper Copper-bearing series the term Mpigon group 

is proposed.

BELL,24 in 1876, finds on lake Winnipeg extensive areas of Laurentian gneiss and Huronian schist. The run of the stratification is pretty 

uniform, averaging from 50° to 60° south of east, being almost at right 

angles to the general strike of the Laurentian and Huronian rocks in 

the great region north and northwest of lake Superior.

BELL,25 in 1877, describes the rocks from the head ol Moose river to 

Michipicoten and lake Superior; also along the Goulais river. Before 

reaching lake Superior there are several broad alternating belts of Laurentian gneiss and Huronian schist. The Huronian hornblende and 

mica-schists are cut by granite veins of various sizes, one of them 100 

feet thick. On the Goulais river there are again alternations of Laurentian and Huronian rocks.

BELL,26 in 1878, gives observations on the geology of the east shore 

of lake Superior from Batchawana bay to Michipicoten river. The 

Upper Copper-bearing series of Mamainse is calculated to have a thickness of 22,400 feet. It consists of a great variety of amygdaloids, volcanic tufas, felsites, cherts, crystalline diorites, sandstones and coarse 

conglomerates, the latter forming one of the most striking features in 

the series as it passes into a bowlder conglomerate. The bowlders are 

sometimes crowded in a sandy matrix, the largest running as high as 

3 feet 8 inches in diameter, but the majority are under 1 foot. Far the 

greater number consist of granite and crystalline schists like those of 

the Huronian series, but there are also found white quartz, amygdaloid 

and gneiss. Granites, gneisses and schists, as well as basaltic dikes, 

are found at many points. Cape Choyye is composed of Huronian rocks, 

which consist of mica-schists and hornblende-schists, slaty quartzite, 

and massive diorite. The rocks of Gros cap are mostly slaty diorite, 

interstratified with siliceous rock, in which occur exposures of purplish 

red hematite. A dioritic slate west of Gros cap holds layers and lenticular patches of felsite and also rounded pebbles of granite, the 

largest of which are 9 inches in diameter.

MACFARLANE,27 in 1879, in discussing Selwyn's paper on the Quebec 

group, maintains that there is frequently found between the water and
62 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

the Laurentian or Huronian hills narrow strips or patches of rocks of 

the Upper Copper-bearing group. Such localities are G-ros cap, south 

shore of Batchawana bay, and cape Gargantua. The conglomerates 

are full of Huronian debris, and in Batchawana bay bowlders may be 

observed of red jasper conglomerate, the characteristic rock of the 

typical Huronian. On Michipi coten island the igneous and sedimentary 

strata of the Upper Copper-bearing rocks have a dip of 25° to the 

southeast, while the nearest Haronian rocks dip 34° to 55° northward.

BELL,28 in 1883, gives a further account of the distribution of the 

rocks of the lake of the Woods and adjacent country. They are not 

different from those mentioned in his previous report for 1872-73. The 

line between the Laurentian and Huronian system, crosses the Winnipeg river at Eat portage, keeps near the railway to a point between 

lake Lulu' and Keewatin millSj where it crosses it diagonally and continues in a westerly direction on the south side of the track.

SELWYN,29 in 1883, as a result of an examination of the north shore 

of lake Superior from Thunder bay to Sault Ste. Marie, and thence 

eastward to Echo lake, fails to find evidence of the supposed unconformability of the Huronian and Laurentian. The author can give no 

better reason for supposing that certain sets of beds belong to the socalled Laurentian and others to the Huronian systems than a considerable difference in the lithological characters. The Laurentian are essentially granitoid, gneissic and feldspathic, while the Huronian are 

quartzose, hornblendic, schistose and slaty. As a whole the latter 

have a somewhat altered aspect and contain pebbles of rocks granite, 

gneiss, quartzite, etc. similar to those which form the Laurentian 

strata beneath them, while others, however, are not recognizable as 

from any known Laurentian sources. Bands of limestone and dolomite, 

more or less crystalline, are found in both Laurentian and Huronian 

areas, and, if we except the disputed form Eozoon, no fossil whatever. The Huronian follows and does not rest un conformably upon 

the Laurentian. The Mpigon or Keweenian is later in age than the 

Anindkie. No definite opinion can be expressed as to the position of 

the crowning overflow of Thunder cape.

SELWYN,30 in 1883, describes the trap and sandstone of lake Superior as unconforinably upon and entirely distinct from the Huronian. 

The series is divisible on the Canadian shore into two, and perhaps 

three divisions, between which there may be slight unconformities, 

which are, however, no greater than might be occasioned by the intermingling of sedimentary strata with volcanic material. The groups in 

ascending order are (1) the shales, cherts, dolomites and sandstones 

interbedded with massive diabase or dolerite of Pie island, McKays 

mountain and Thunder cape. (2) Conglomerates, shales, sandstones 

and dolomites, interstratified with massive beds of volcanic material, 

amygdaloids, melaphyres, tuffs, etc., many thousands of feet thick, 

occupying the east shore of Black bay, Mpigon strait, St. Igiiace,
VANHISE.] LAKE SUPERIOR REGION. 63

Micliipicoten island, Gargantua, Mamainse, etc. (3) The Sault Ste. 

Marie sandstone, which may be only the upper part of 2 without any 

intermingling of volcanic material. The whole together is Lower Cambrian, there being no evidence whatever of their holding any other 

place in the geological series. The first of these groups is the Animikie series while the second is the Keweeuian.

SELWYN,31 in 1885, places the crowning overflow of McKays mountain, Thunder cape and Pie island, etc., as a part of the Animikie. 

There was found no evidence of unconformity from the base of the 

Animikie to the top of-the Keweenian as developed on Thunder cape 

and the surrounding region.

LAwsoN,32 in 1886, gives a report on the geology of the lake of the 

Woods region, with special reference to the Keewatin (Huronian ?) belt 

of the Archean rocks.

Comprising a large part of the lake of the Woods is a series of crystalline and semi-crystalline schists to which the term Keewatin is 

applied. The term Huronian is not used, because it is very doubtful 

if the series belongs to this period. The rocks are found to differ fundamentally ill lithological character from Logan's Original Huronian.

In the Keewatin, quartzites are unimportantj there are no true basal 

conglomerates; and the fragmentals of the lake of the Woods are of 

volcanic origin. No bedded limestones were observed. Structurally, 

also, the two series are fundamentally different. The lake of the Woods 

schists are folded with the associated granite gneisses, which are referred to the Laurentian, while the Huronian series has not partaken 

of the folding to which the adjacent gneisses have been subject. Further, the large areas of granite are found to be intrusive in both the 

Laurentian gneiss and Keewatin schists, while in the Euronian of 

Logan such intrusions, if present at all, are mentioned at only one locality. The slate conglomerate of Dore* river appears to resemble the 

lake of the Woods agglomerates, but this area is distant from, the typical 

Hutonian region and appears to differ from it lithologically, as well as 

being in a nearly vertical attitude. These differences between the 

Dore" and Huron areas, with their geographical separation, may warrant 

the belief that possibly Logan embraced under one designation two 

distinct series. As to Prof. Irving's position that the Animikie series 

is probably the equivalent of the Huronian, it is considered exceedingly 

probable that the flat-lying unfolded Animikie is much later than the 

lake of the Woods schists.

The rocks of the region, including both the Laurentian and Keewatin, 

comprise gneiss, granite, felsite, schistose hornblende rocks, diabase, 

diorite, serpentine, coarse clastic rocks and agglomerates, mica-schists, 

slates, quartzites, clay-slates, felsitic schists, hydromica and chloriteschists, carbonaceous schists and limestones. The massive granites 

sometimes grade, into foliated gneisses. Dikes of granite have sometimes foliated structures parallel to their sides. The agglomerates are
64 PRE-CAMBRIAN EOCKS OF NORTH AMERICA. [BULL. 86.

not ordinary elastics, but are of volcanic origin. Both paste arid included fragments have evidently had a common origin and been laid 

down together, perhaps not even always under water. The fragments 

are usually more or less elongated or lens-shaped, due to pressure. 

The greatest planes in the fragments are parallel with the planes of 

schistosity, which are usually observably identical with those of bedding; at times the agglomerates merge into mica-schists on the one 

hand and into hornblende-schists on the other. The mica-schists, 

micaceous slates, clay-slates, and quartzites constitute a natural group 

of rocks intimately associated, both as regards their origin and their 

present relations in the field. They are all probably ordinary metamorphic elastics. The felsitic, sericitic and hydromicaceous schists 

are probably sediments, the material of which was probably volcanic. 

The mica-schists quite frequently pass into finely laminated micagneisses. The limestones are found only in small masses and seem to 

be vein stones rather than bedded strata.

The Keewatin schists and Laurentian granitoid gneisses are found 

oftentimes to be apparently interbedded. At other times the junction 

is of the most irregular sort, tongues of schists running into the granite, 

or masses of it being contained in the granite and gneiss. The gneiss 

acts in many places as though it had been in a fluid state intruding 

the schists, and the conclusion is reached that the junction, instead of 

being that of mterlaminated sediments, is that of a set of schistose 

rocks which have been intruded by^fluid ones, the fluid material often 

placing itself along the parting of the schist, at other times cutting 

across it or including fragments of it. If this conclusion is true the 

supposed conformable junction of the two series at certain localities is 

no proof of true conformity, because the foliation of the granitoid 

gneisses, if these rocks were once viscid or plastic, is quite independent 

of any arrangement due to sedimentation that they may have possessed. 

This conclusion does not imply that the gneisses and schists may not 

have been originally sedimentary and conformable. However, the 

author inclines to the belief that the granitoid gneisses of the Laurentian were never aqueous sediments.

The'granitic intrusions of the lake of the Woods are grouped into 

ten main centers. The granite cuts both the granitoid gneiss (Laurentian) and the various rocks of the Keewatiu series, and is therefore of 

later age than either. A granite, the intrusive character of which is 

undoubted, sometimes merges in the same rock mass into a granitoid 

gneiss. There is a marked association of felsites or microgranites with 

the main granite mass, there being an apparent tendency on the part 

of the former to an arrangement concentric with the periphery of the 

granite. Upon various sections a certain periodic arrangement of the 

Keewatin is made out, upon which1 as a basis it is found that the maximum thickness of the series is in the neighborhood of 20,000 feet. ° As 

to the general stratigraphical relations of the Keewatin, the conclusion
VAHHisE.1 LAKE SUPERIOR REGION. 65

is reached that they have been laid down and folded within a trough 

in the Laurentian formation.

HERIUCK, TIGHT, and JONES, 33 in 188G, find on the north shore of 

lake Superior three distinct groups of rocks with their respective intrusives, granitic, schistose, and conglomeratic. The granites are found 

underlying the schists in such a way as to suggest that they have been 

intruded beneath them, although similar granites constitute the pebbles of the basement conglomerates in the schists. The schists are met. 

amorphosed at contacts with the granites; the schists and schist-conglomerates especially, in several places, have been altered to porphyry 

and felsite-porphyry by contact with the eruptives. The third group 

consists of basement conglomerates, consisting of fragments of all the 

varieties of rock included in the other two series. Periodic overflows of 

igneous matter have left vast sheets of diabase, and there is a strong 

interaction between the sedimentary and eruptive rocks.

McKELLAtt, :!4 in 1888, describes the Aniinikie on the north shore of 

lake Superior as always resting unconformably upon the crystalline 

and schistose i'ocks to which the term HUronian is applied, the contacts being found at many points, In lithological character!sties these 

two series are fundamentally different. The original Huronian and 

the schists underlying the Animikie are compared, and it is concluded 

that they are the equivalent of these rocks rather than of the Animikie series; therefore the latter is later than the Huronian. The contacts of the Animikie and Keweenawan formations show that there is 

an unconformity by erosion between the two.

LAWSON, r'5 in 1888, reports on the geology of the Rainy lake region. 

The pre-Oambrian rocks are divided into an upper and lower Archean, 

as at the lake of the Woods. The upper is a bedded schistose and 

metamorphic series, while the lower is granitic, gneissic or syenitic in. 

character. In the upper division two groups are recogni/ed, one the 

Keewatin of the lake of the Woods, and the other, inferior in position, 

is given the name Coutchiching. In the lower division, distinctions of 

stratigraphical sequence and relationship, if any such ever existed, 

have been obliterated, and for this the term Laurentian is retained. 

These rocks can. be classified only on a petrographical basis. The contacts of the Keewatin with the Goutchiching and Laurentian are very 

frequent. The relations between the Keewatin and Laurentian are 

exactly like those described as maintaining upon the lake of the 

Woods. The schists are intruded by the granite, fragments of the 

former being included in the latter, and they are sometimes fused at 

the contact. Very frequently near the point of junction the Keewatin 

rocks become more crystalline and are glistening hornblende-schists.

At two localities basal conglomerates are found between the Keewatin and Coutchiching. At the first of these, Rat-root bay, Keewatin 

conglomerate rests upon Coutchiching schists, the conglomerates containing water-worn fragments of quartz and bowlders of granite. The 

Bull. 86 5
66 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BCLL.SC.

second is at Grassy lake, where there is a pebbly conglomerate at the 

base of the Keewatin. The contacts of the Keewatin and Coutchiching are usually in apparent conformity, and the mapping of the series 

is made to rest upon lithological characters rather than upon structural 

discordance, although it is recognized that the conglomerates at the 

two localities mentioned are indicative of erosion, at least in some 

places, between the two series. The apparent accordance affords little 

evidence as to the question of original conformity or unconformity, 

because the two formations have been squeezed together; but the 

marked contrast in lithological characters indicates an abrupt change 

in the conditions of formation.

The thickness of the Keewatin rocks is calculated to be about five 

miles. The rocks are found in the main to be of clastic origin, but 

probably in the nature of volcanic debris rather than water-deposited 

sediments, although a small quantity of the materials is of the latter 

character. The volcanic d6bris of the Keewatin has a basic and an 

acid division, the latter being higher in the series than the former. 

Microscopical study leads to the conclusion that the series has been 

subjected to great pressure, as is evidenced by the fracture of the 

grains as well as by the schistose structure. The granite bowlders 

found in the conglomerates may either be ordinary detritus or may 

have been brought up from beneath by volcanic forces, although the 

former is the more probable. All of the granites of the region appear 

to be in some degree later than the Keewatin rocks, but this does not 

imply that there was not a granite shore for the basin in which the 

Keewatin rocks were deposited. The author has no doubt that the 

original floor upon which the Keewatin and Coutchiching rocks were 

deposited was fused at the time of disturbance and appears now to us 

as the foliated granite of the Laurentian. The granite bowlders of the 

Keewatin agglomerates may have been derived from a granite basement 

now obliterated by subsequent plutonic fusion.

The Coutchiching series consists of mica-schists, or mica-schists in 

which feldspar is present. Hornblende has been observed only in one 

instance. No limestones or conglomerates have been discovered. The 

schistose structure is believed to represent original sedimentation. Calculating the thickness upon this basis, it is found that the formation 

has an average thickness of 4 or 5 miles. The relations of the Coutchiching series to the Laurentian are found to be precisely the same as 

between the Keewatiu and Laurentian. In the Coutchiching series 

there are no intercalations of recognizable volcanic rocks such as are 

found in the Keewatin, the rocks being acid crystalline schists which 

are regarded as ordinary metamorphosed quartzose sediments, with 

perhaps also volcanic material, although in no place has it been possible conclusively to prove this.

The Laurentian gneiss is intermixed with granite in such a way as to 

make it impossible at times to separate them. Its- structure, if it has
VANHISB.] LAKE SUPERIOR REGION. 67

any, is so complex that no attempt was made to work it out, and, while 

parts of the granite seem to belong to the Laurentian proper, it is certain that granitic eruptions have occurred in this series after the main 

mass of the rock had solidified. The belts of Keewatin rocks which 

encircle the Laurentian areas are anastomosing or confluent, forming a 

continuous retiform area, the meshes being occupied by the Laurentian 

gneiss. At their nodes or points of confluence, these belts have their 

greatest width. The Coutchiching schists dip away from, the Laurentian bosses in all directions, so that the general anticlinal structure of the belt is made up of three anticlinal domes. These relations 

are taken to mean that the surrounding schistose rocks represent sedimentary beds which have been thrust aside by the entering granite. 

Along the contacts of the Laurentian and Coutchichmg are found such 

minerals as andalusite, staurolite, and garnet. Besides the granite 

masses, which cut all three of the previous series and thus are later than 

all, are also numerous diabase and trap dikes, which cut the series 

mentioned and the granite besides.

iNGrALL, 36 in 1888, in describing the mines and mining of lake Superior, 

finds the rocks to consist of Laurentian gneisses and granite, within 

which are found considerable areas of plutonic and volcanic rocks and 

metamorphic slates, considered to be Huronian, while overlying these, 

chiefly about Thunder bay and lake Nipigon, are the sedimentary and 

volcanic rocks of the Animikie, Mpigon, and Keweenian groups, which 

are in approximately a horizontal position and contrast markedly with 

the steeply inclined or almost vertical older rocks. The Animikie formation is divisible into an upper and lowe'r portion. The chief character of the lower division is the preponderance of siliceous rock, such as 

chert andjasper, Avhich are often accompanied by ferruginous dolomite 

with magnetite; while the upper division is formed for the most part of 

black, soft argillaceous argillites, which are occasionally dolomitic and ferruginous, and sometimes contain silica in such proportion as to approach 

the character of the lower division. The thickness of the Animikie is 

placed at 12,000 feet. The traps of the Animikie are concluded to be 

intrusive, frequently breaking «as they do across the beds. In one case a 

sheet is seen to divide into three tongues. The dark color of the upper 

division of the Animikie is due to the presence of carbon. Patches of 

basal conglomerates are occasionally found at the base of the Animikie, 

lying in hollows in the old Archean sea bottom, the fragments consisting 

in general of granitic material.

SELWYN,37 in 1890, announces the discovery by Ingall of traces of a 

fossil in the Animikie rocks. A part of the impressions are pronounced 

by Matthew to be similar to Eophyton, while for others the names 

Taonichuites and Cteriichnites are proposed. A part of them are of 

similar origin with characteristic tracks of the Cambrian rocks of the 

St. John group of New Brunswick. °
68 PRE-C AM BRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

LAWSON,38 in 1890, discusses the internal relations and taxonomy of 

the Archean of central Canada. The Keewatin and Coutchiching are 

again described and the characteristic contacts which they have with 

the Laurentian. To the upper division, the Keewatiu and Coutchiching, 

since they are sedimentary rocks, the principles of strati graphical geology apply, and to cover these two series is proposed the term Ontarian, 

of vSystemic value. The principles applicable to the lower division, the 

Laurentian, are those of eruptive geology, since these rocks are of 

igneous origin. In the Laurentian there are at least two generations of 

rocks which are distinguishable in the Hunter island district, but both 

are the result of the crystallization of a subcrustal magma.

BELL,39 in 1890, gives the following as the chief Huronian areas 

about lake Superior, in Ontario. An important area lies around Michipicoten at the northeast angle of lake Superior, running for 60 miles 

west and 20 miles south of that point, and extending inland to Dog 

lake, a distance of 45 miles. Another large area stretches from the 

Pic river eastward or inland to Nottamasagami lake, and westward 

mingled with granites and greenstones, to Nipigon bay. Two extensive belts run eastward from lake Mpigon, one of which crosses Long 

lake. West of Thunfler bay, and stretching to the international 

boundary line, there is a large area which gives off arms to the northeast and southwest; and several belts and compact and straggling 

areas occur between this and the lake of the Woods basin, one of which 

follows the course of the Seine river. The lake of the Woods area, 

which has been already alluded to, occupies the whole breadth of the 

northern division of that "lake. An important belt starts between 

Rainy lake and lake of the Woods, and running northeastward has a 

breadth of 45 miles where it crosses the line of the Canadian Pacific 

railway. Minnietakie and Sturgeon lakes lie within this belt.

The Huronian is divided into a lower and upper division, although 

no horizon has been agreed upon at which to draw the line between the 

two even locally. There is no evidence whatever that the two divisions 

are unconforinableor that the lower part of the upper division are basal 

conglomerates. Conglomerates are foivjid indifferently throughout both 

lower and upper divisions.

The lower division includes the Keewatin of Lawson and its equivalents. It consists largely of a variety of crystalline schists, in which 

the prevailing color is dark green or gray. Among these may be enumerated micaceous, dioritic, chloritic, argillaceous, hornblendic, taleoid, 

felsitic, epidotic, siliceous, dolomitic, and plumbagenous. There are also 

crystalline diorites or diabases of various shades of gray and greenish 

gray (mostly dark), argillaceous and dioritic slate-conglomerates, granites and syenites, impure, banded, and schistose iron ores, dolomites and 

imperfect gneisses. Among the commoner of the rocks of this division 

are fine grained mica-schists and dark green dioritic or hornblendic 

schists. Two kinds of conglomerates are also abundant, one having an
VANHISE.] LAKE SUPERIOR REGION. . 69

argillaceous matrix with rounded pebbles of syenite and granite of various kinds, and some of -the. other Huronian rocks, but very seldom of 

gneiss; the other with a dioritic matrix, and often with rounded pebbles 

also. But, in perhaps theniajority of cases, what were formerly considered 

as pebbles are really concretions of a lenticular form, and differing but 

slightly from the matrix in color and composition. They are best seen 

on wetted surfaces of cross sections of the rock, where they appear as 

parallel elongated patches tapering to a point at each end. Both hematite and magnetic iron ores are common in these rocks. Gneiss is not 

common in the Huronian, and it differs from the ordinary Laurentiau 

gneiss in being imperfect and slightly calcareous.

In the upper division of the Huron!an probably the most abundant 

rock in Ontario is what may be called a graywacke, but which in the 

older reports was often styled a " slate conglomeratej" but it also includes clay-slates, argillites, felsites, quartzites, ordinary conglomerates, jasper conglomerates, breccias, dolomites, serpentine, etc. In 

some localities the nearly vertical bands of quartzite, having withstood 

denudation better than the other rocks, remain as conspicuous hills or 

ridges, and this circumstance has caused their relative volume in the 

series to be overrated by superficial observers. The materials forming 

the graywackes and the stratified quartzose diorites have been derived 

from volcanic sources. The igneous character of the Huronian is farther 

shown by the large masses and areas ot greenstone (diorites or diabases), granites, syenites, and other eruptive rocks which are so largely 

mingled with both the lower and upper portions of the Huronian system in all parts of their distribution, forming indeed one of its characteristic features. The crystalline greenstones occur either as compact 

areas, wide elongated masses, dikes, or thick interstratifying beds in 

nearly all the Huronian areas. In many cases the dioritic schists may 

have been originally massive, but assumed the cleaved structure by 

pressure when incorporated among stratified masses. The commonest 

position of the granite and syenite areas is within but to ward the borders of the Huronian tracts; but they sometimes occur in the Laurentian country, in their immediate vicinity, or at a distance from them in 

the direction of the longer axis of the Huronian areas.

Unconformably above the Huronian is the Cambrian system, which 

comprises, in the ascending order, the Animikie, Mpigon, and Potsdam 

formations.

The Animikie formation, in ascending order, consists of arenaceous 

conglomerate, with pebbles of quartz, jasper, and slate, seen on the 

north shore of Thunder bay; of thinly bedded cherts, mostly of dark 

colors, with argillaceous and doloinitic beds; of black and dark argillites, and flaggy black shales, with sandstones and ferruginous dolomitic bands and arenaceous beds, often rich in magnetic iron, together 

with layers and intrusive masses of trap (diabase). The Animikie formation occupies a great triangular area north and west of lake Supe-
70 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [nuu,86.

rior, the base of which is 60miles in length and the arms 40 and 80 miles, 

respectively.

The Mpigon formation, resting with apparent unconformity upon the 

Animikie formation, is characterized by reddish marls, sandstones, and 

conglomerates, with a large proportion of variously colored trappean 

beds and masses, a considerable part of which is amygdaloidal. The 

Mpigon formation occupies a great area about Mpigon lake and considerable areas at the east end of lake Superior and on Michipicoten 

island.

On the east side of Hudson bay and on the islands off the coast volcanic and sedimentary rocks are largely developed, comprising conglomerates, sandstones, limestones, chert breccias, shales, quartzites, 

argillites, porphyries, crystalline traps, amygdaloids, tufas, etc. The 

upper part of these may correspond to the Mpigon and the lower to 

the Animikie.

The sandstones of Sault Ste. Marie, of the peninsula between Goulais 

and Batchawana bays, isle Parisienne, etc., seem to be of Potsdam 

age. These sandstones are mostly red, but, unlike the Mpigon formation, they appear to be free from local disturbance and- lie almost flat. 

Although they resemble some of the sandstones of the Mpigon series 

at Mamainse in red color, they are believed to be newer and probably 

unconformable to them.

LAWSON,40 in 1891, states that the granite of Saganaga lake is found 

with abundant and clearly observed evidences of eruption, breaking 

through the Keewatin rocks, including the upper Vermilion fragmental 

rocks of Ogishki lake with their associated slates and grits. It is concluded that the break between the upper and lower Vermilion, described by Van Hise, is within the Keewatin group, dividing it into an 

upper and lower series, and that this break is therefore below the 

Animikie. It is further said that the conglomerates of the upper 

Kaministiquia series come out close to the shores of Thunder bay and 

form the basement upon which the undisturbed A.nimikie rocks rest with 

strongly marked unconformity. The following succession for the region 

northwest of lake Superior is presented: Keweenawan or Mpigon 

group; unconformity; Animikie group (possibly Huronian); unconformity; upper Keewatin series, unconformity; lower Keewatin 

series; unconformity^); Ooutchiching group; eruptive unconformity; 

Laurentian system, the granites and gneisses of which cut both Keewatin and Ooutchiching groups.

SMYTH (H. L.),41 in 1891, describes the structural geology of Steep 

Bock lake, Ontario. The lake is roughly in the shape of a letter M, the 

top is to the north, and its arms conform to the strike of the rock series. 

The rocks are divisible into three principal groups. The lower consists 

of granites and gneisses, and is designated as the basement complex. 

Eesting upon the basement complex is a series of rocks about 5,000 feet 

in thickness, composed of nine persistent formations, which together
VAN man.] LAKE SUPERIOE REGION. 71

constitute the Steep Eock series. Lying across the edges of the Steep 

Rock series, at the southeastern part of the lake, is a later series of 

granites, porphyries, and hornblende rocks which pass upward into 

the schists of the Aticokan river and are designated the Aticokan 

series. The granites and gneisses of the basal complex are cut by various dikes, which are of three kinds, those which supplied pebbles to 

the conglomerate at the base of the Steep Eock series5 those which 

traverse both the basement complex and the Steep Eock series but 

have been subjected to the folding; and, third, a single massive dike 

which is subsequent to the latest period of folding.

The formations of the Steep Eock series, in ascending order, are conglomerate, lower limestone, ferruginous horizon, interbedded crystalline traps, calcareous green, schists, upper conglomerate, greenstones 

and greenstone-schists, agglomerate, and dark gray clay-slate. It is 

then a series of sediments and interbedded eruptives.

Along the whole course of the lake this series dips at very steep angles, ranging from 60° to 80° away from the basement rocks, upon 

which they hang as a time-worn fringe having no extension inland. The 

basal part of the Steep Eock series is a bed having a maximum thickness of nearly a hundred feet,.presenting the various phases of a conglomerate, coarse and fine, and quartzite and quartz-schists with feldspar. The lowest member contains rounded and waterworn pebbles of 

quartz and greenstone, the largest being a foot in diameter. Near the 

junction of the Steep Eock series and basal complex both are sometimes very similar in composition, so that it is impossible to draw the 

lines between them by this criterion. There is an. apparent transition 

from one rock into the other. The transition zone has a highly schistose structure in the regional direction, which crosses the course of contact and the bedding nearly at right angles and is traced from the transition zone into the undoubted granite into which it gradually dies out. 

This transition is explained as due to probable disintegration of the 

basement complex before the Steep Eock series was deposited, combined 

with subsequent powerful dynamic movements which have affected both 

series. * 

The Steep Eock series is folded into an eastern synclinal, a middle 

anticlinal, and a western synclinal, the latter being faulted. The axes 

of these folds have a high pitch to the southward, varying from 60° to 

nearly 90°. Throughout the whole area is a regional cleavage which 

has a nearly uniform direction transverse to all the members of the 

Steep Eock series and also the contact between this series and the 

basement complex. This has largely obliterated the original lamination of the sediments and is now the dominant structure. It is therefore the last force which has left its marks upon the rocks of the la,ke. 

Before this last force acted upon the rocks, the"Steep Eock series had 

been folded into a southwestward dipping monoclinal which, under the 

action of the cleavage-producing force in a northeast and southwest
72 PRE-CAMBRIAN BOOKS OF NORTH AMERICA. [BCLUSO.

direction, caused the present fluted outcrop of the formations of the 

Steep Eock series. That the basement complex itself yielded to this 

latter force is shown by the irregular outcrops of the dikes cutting it. 

As a result of the study the following general conclusions are reached: 

The contact of the lowest horizon of the Steep Rock series with the 

basement complex is one of erosion. The complex at the time of the 

deposition of the Steep Eock series was made up of consolidated crystalline rocks, and there is no evidence whatever that it has since undergone fusion or recurred to the condition of a magma. The rocks of the 

Steep Eock series have been subjected at two periods, more or lens distant from one another, to great orotechuic forces, which acted the first 

in a northeast and southwest direction, and the second in a northwest 

and southeast direction. The latter force has imposed upon all the 

rocks of the region a northeast structure which has largely, but not 

entirely, obliterated preexisting lamination in the sediments and 

schists of the Steep Eock series. The two .orotechnic actions have 

produced great developments of autoclastic schists, both iu the granites and in the rocks of the Steep Eock series, the present structure 

of which was induced and determined in direction by the later force.

SECTION II. WORK OF THE EARLY UNITED STATES GEOLOGISTS AND

ASSOCIATES.

ScHOOLCRAFT/2 in 1821, in his Narrative Journal of Travels iu the 

"Northwest, makes various observations on the crystalline rocks. At 

Granite point is found a bluff of granite which is traversed by irregular veins of greenstone trap. The sandstone laps upon the granite and 

lits into its irregular indentations in a manner that shows it to ha<ve 

assumed that position subsequently to the upheaving of the granite. 

Its horizontality is preserved even to the immediate point of contact. 

All the rock along the south shore of Lake Superior is either red or 

gray variegated sandstone, which appears to be referable to one formation. On passing by the Porcupine mountains, the red sandstone is 

visible along the shore in a position nearly vertical, dipping under the 

lake toward the north. Eed sandstone in a vertical position is found 

at the mouth of the Montreal river and for a few miles beyond it 

toward Chequainegon bay. On the St. Louis river, after passing red 

sandrock in a horizontal position, is found on the banks of the river a 

slate (argillite) in a vertical position traversed by green stone and milky 

quartz. At the grand portage of the St. Louis the country is rough, 

consisting of slate in a vertical position. This continues for a longway and is succeeded by hornblende, which continues to the head of 

Grand rapids.

OATLIN,43 in 1840, finds the red pipestoue quarries of the coteau des 

Prairies to consist of a perfectly stratified rock in layers of light gray 

and rose or flesh colored quartz, the deposit being evidently sedimentary and of secondary age.
VANIIISE.] LAKE SUPEKIOR KEGION. 73

LOCKE/" in 1811, describes the rocks of Copper harbor as- well as the 

whole of Keweenaw peninsula as decidedly metamorphic, showing 

every degree of change produced by igneous action, from unchanged 

sandstone to compact greenstone. The original stratification is generally more or less evident; some layers bear evidence of semifusion with 

a corresponding degree of induration, while others seem scarcely to 

have been altered.

CUNNINGHAM, 45 ill 1845, SANDERS, 46 ill 1845, CAMPBELL," SANDERS, 48

GRAY,49 in 1845, GRAY,50 iii .1840, give various detailed observations as 

to the mineral regions of lake Superior, but give little or nothing of 

structural interest.

ROGERS,51 in 1846, describes the red sandstones and conglomerates of 

lake Superior as resting uneouforniably upon highly inclined slate rocks 

undoubtedly Primal, and the Potsdam sandstone of the New York survey at Chocolate and Carp rivers, and therefore of post-Paleozoic age.

OwEN,52 in 1847, finds the horizontal sandstone to overlap the crystalline and metarnorphic formations at the southern portion of the 

Chippewa land district near the falls of the streams flowing into the 

Mississippi. The region to the north is based upon crystalline, granitic, and other intrusive rocks. North of.the summit levels of the 

Chippewa land district the peculiar formations of the lake "Superior 

country commence. These are red sandstones, marls, and conglomerates, occasionally penetrated by intrusive ranges of hornblende, greenstone, trap, and amygdaloid similar in their general aspect to the contemporaneous ranges of igneous rocks which occur in the mining district of Michigan. Besides this trap formation, there is an entirely 

distinct trap system in immediate juxtaposition with which strata have 

been discovered which are as old as if not older than the Lingulabeds of 

the Potsdam sandstone of New York.

LocKE,53 in 1847, speaks of the relation of the trap rock and sandstone at Presque isle, and submits a drawing of it.

WniTNEY,54 in 1847, describes the wide band of trappean rocks commencing at the extremity of KeweenaAv point as continuing its course 

uninterruptedly as far as the Montreal river. Its distance from the 

lake between Portage and Ontonagon is generally from 8 to 10 miles. 

The highest and most imposing cliffs are found north and east of Agogebic lake. Beyond Agogebic lake the trap range widens and forms 

several ridges, between which it is not impossible that there may be 

sandstone. The Porcupine mountains embrace a system of trappose 

rocks in three tolerably distinct ranges. All the country north of the 

northern edge of the trap range from the Ontonagon to the Montreal, 

with the exception of the trappose rocks of the Porcupine mountains, is 

covered by the red sandstone of lake Superior.

OwEN,55 in 1847, gives many details of the formations of the interior 

of the Chippewa land district, and of the formation of lake Superior. 

In the first district are seen many varieties of granite, syenite, green-
74 PRE-CAMBRJAN ROCKS OF NORTH AMERICA. [BULL.86.

stones, hornblende-rock, gneiss, and mica-slate. Magnesian aud mag1 , 

netic slates are capped unconformably by pebbly sandstones for nearly 

a mile along Black river. The red sandstone of lake Superior on Eaymonds creek is estimated by Eaudall to be 10,000 feet in thickness.

NORWOOD,56 in 1847, describes various rocks on the St. Louis river 

in the district between. Fond du Lac and the falls of St. Anthony, and 

from the mouth of the Montreal river to the headwaters of the Wisconsin river by way of lake Flambeau. On the St. Louis river a conglomerate is found to rest unconformably upon the lower slates, the 

junction of the slates and conglomerates being exposed.

ROGERS,57 in 1848, remarks that the south shore of lake Superior is 

outlined by a series of east and west dikes.

WniTN-EY,58 in 1848, finds in the townships near the Anse fossiliferous 

limestone, which seems to be surrounded by and has been deposited on 

the lake Superior sandstone.

FOSTER,51' in 1848, in passing from Copper harbor to L'Anse, finds 

that the trap, instead of being forced through the layer of sandstone, 

as on the northern slope of Keweenaw point, protrudes through a fissure 

in it, causing an anticlinal axis. A few miles farther south the sandstone is nearly horizontal, being in a series of gentle undulations. At 

L'Anse the sandstones overlie the talcose, argillaceous, and hornblendic 

slates unconformably, while 15 miles southeast of L'Anse the granites 

protrude through these schists.

Upon the Michigauime river were found in order beds of quartz a.nd 

feldspar, hornblende, and specular oxide of iron, associated with talcose 

and argillaceous schists. On the left bank of the Michigamme (Sec. 1, 

T. 46 1ST., K. 30 W.) is a hill 170 feet'high, which exposes a very large 

mass of nearly pure specular oxide of iron. About 40 feet from the 

escarpment is a inetamorphic rock composed of rounded particles of 

quartz and feldspar with masses of ore intermingled like the pebbles of 

a conglomerate.

Iron ore and marble were observed along the Menominee, as well as 

various other kinds of rocks, including granite, hornblende-slate, talcose slate, etc. At Sandy portage, on the Menominee, is a class of plutonic rocks older than the traps of Keweenaw point, which were protruded among the slates and then denuded before the deposition of the 

sandstone; for the slates are intercalated among the igneous rocks 

with a vertical inclination, while the sandstone rests horizontally or 

nearly so upon them. This sandstone is regarded as the oldest of the 

Paleozoic rocks and is the equivalent of the sandstone on the northern 

slope of the upper peninsula. Besting upon this sandstone is a limestone which is sparingly fossiliferous.

JACKSON,60 in 1849, describes the sandstone of Keweenaw point remote from the trap as horizontal or but slightly waving, while near the 

trap rock it is as high as 30°. The conglomerate is limited to the borders of the trap and is of the same age as the finer grained sandstone
VANHISE.] LAKE SUPERIOR REGION. 75

with which it alternates. At the line of junction of the trap rocks and 

sandstone the two are interfused, producing the metamorphic rock 

amygdaloid, which resembles the vesicular lavas of volcanoes, but has 

its cavities filled with a great variety of curious and interesting rninerals. On isle Koyale about one quarter of the area is sandstone and 

conglomerate and the remainder trap, which formed ridges extending 

the whole length of the island.

WniTNEY,61 in 1849, describes the iron ore of the upper peninsula of 

Michigan as existing in the form of solid ridges and knobs interstratiRed 

with banded jasper, the whole evidently of igneous origin.

AG-ASSiz,62 in .1850, describes the outlines of the shore of lake Superior as largely due to six different sets of dikes of different inineralogical character, and each system running parallel to one of the main 

shores lines, although it would be a mistake to ascribe the form to any 

single geological event. Its position in the main is doubtless determined by a dislocation between the primitive range north and the sedimentary deposit south. The rocks of the north shore of lake Superior 

are extensively metamorphic. The new red sandstone passes into porphyries, into quartzite, granite and gneiss, the metamorphism being 

more or less perfect, so that the stratification is still sometimes preserved or passes gradually intp absolutely massive rocks.

JACKSON,63 DlCKENSON, MdNTYRE, BARNES, IiOCKE, FOSTER and

WIIITNEY, GIBES, HILL, BURT, and HUBBARD, in 1850, report upon 

the mineral lauds south of lake Superior in the state of Michigan.

JACKSON,64 describes the red sandstones and conglomerates of Keweenaw point as existing there anterior to the elevation of the trap 

rocks, being derived from the deposition of fine sand and pebbles from 

preexisting Primary rocks, such as granite, gneiss, or mica-slate. Porphyry furnishes a large portion of the debris, but it is doubtful if this is 

not a semi-fused sandstone. There is no reason to believe that igneous 

agencies had anything to do with the origin of the pebbles of the conglomerate, for they are rounded by the action of water. From the 

circumstance that the conglomerate borders the trappean rocks it is 

supposed an ancient shore may have existed along that line. It is cer: 

tain that the finer sandstone is more remote from the trap than the conglomerate is, and that it is less uplifted and inclined as it recedes from 

the trap band. Near the junction of the two rocks the strata dip 25° 

or 30°, while remote from it the sandstone is nearly horizontal. The 

mineral composition, association, and contents of the sandstone are iclentical with those of Nova Scotia, Connecticut, Massachusetts, and New 

Jersey, belonging to the new red sandstone series; and that the lake 

Superior belongs to this age has been confirmed by the discovery by 

C. F. Merion of a tract of limestone in the midst of the sandstone of 

Keweenaw point near the Anse. The limestone contains Pentamerus 

oblongus, and according to Whitney has a dip of 30°, while the overlying sandstone is horizontal and has been deposited around it. The
76 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BOLL. 86.

sedimentary strata have undergone great change by the action of the 

trap rocks. Along the line of the junction a chemical combination of 

the materials of the sandstones and trap rocks took place, forming the 

vesicular trap called amygdaloid, while there has further resulted from 

this action a breccia ted or trap tuff, consisting of broken pieces of 

amygdaloid and sandstone. At other times the sandstone is indurated 

into a flinty red rock resembling jasper. At the Copper falls mine is 

a case of what appears to be an Ortkocera in the breccia of amygdaloids 

and altered limestones. May it not have been torn from a subjacent 

bed of Silurian limestone by the agency of the intruded trap rocks? 

At the coast off lac la Belle the sandstone in contact with trap has a 

dip to the south of 30°, while at point Isabelle the sandstone cliffs are 

nearly horizontal.

LoCKE05 finds near L'Anse that the trappean rocks contain fragments of slate distributed through it and converted into a hornstone 

when in "small pieces, like the eruptive granite of Pigwacket mountain, 

New Hampshire. At point IsTo. 2, west of Presque isle, is a junction of 

red sandstone and syenite. The mass of syenite intersected by dikes 

of trap is under the sandstone and seems to have but slightly affected 

it.

.FOSTER and AVniTNEY 66 accompany their synopsis of their explorations by geological ma,ps of the region between Portage lake and the 

Montreal river, Keweenaw point, isle lioyale, and the region between 

Keweenaw bay and Chocolate river.

WniTNEY 67 finds the rocks in the district between Portage lake and 

the Ontonagon river to comprise the following: First, the red sandstone of lake Superior, the age of which can not be determined, as it is 

destitute of fossils. It lies directly upon the granitic rocks. Second, a 

bed of fossiliferous limestone of the Lower Silurian system, which 

occurs in an isolated position and has but a limited extent, and the 

relations of which to the sandstone have not been determined with certainty. Third, the trappean rocks. Fourth, granitic and syenitic 

rocks, with hornblende and greenstone. The farther the red sandstone is removed from the trappean rocks, so much nearer do its strata 

approach to the horizontal and also become lighter color and more 

fragile. The conglomerate of Keweenaw point occurs mixed and intercalated in such a manner with the sandstone as to leave no doubt of 

their common origin and identity of age. In general the beds of conglomerate increase in frequency in nearing the trap. The sandstone 

does not repose directly on the trap, but almost invariably a bed of 

coarse pebble rock is found interposed between. A trap breccia found 

at Cushinan's seems to be HI product of the interfusion of trap and 

sandstone. Compact quartz rock or jasper 'occurs abundantly in mountain masses in the Porcupine mountains.

Whituey describes a deposit of limestone which rises to a height of 

about 300 feet above the general level of the country near L'Anse.
VANHISK.] LAKE SUPERIOR REGION. 77

The limestone is indistinctly stratified and dips from zero to 30° at 

various points. At certain places it contains numerous fossils, .but 

the greater part of the rock seems to be destitute of them. Among 

the fossils are encrinites, orthoceratites, and others. The country 

around is low and swampy, but the indications are for nothing but 

sandstone horizontally stratified. As the limestone is apparently 

inclined at an angle of 30°, it seems evident that this is the oldest rock, 

though it can not be denied that the stratification of the limestone is 

very obscure and in some places it appears to lie nearly horizontal. 

On the data collected the author feels unwilling to pronounce which is 

the older formation.

FOSTER 68 finds at Copper harbor the junction of the trap and conglomerate. At the point of contact the trap is vesicular, but a few feet 

distant amygdaloidal. The conglomerate is made up of rounded pebbles of greenstone, porphyry, and rarely granite, cemented by a dark 

iron sand, with carbonate of lime among the interstices. Near the 

Quincy mine the conglomerate, or rather sandstone, containing quartz 

pebbles, forms the gorge of the stream below the falls, and differs essentially from that on the northern slope of Keweenaw point. Between the sandstone and compact trap is a bed of red slaty trap associated with amygdaloid. At L'Ause sandstone and conglomerate are 

found resting unconformably upon chlorite-slate, novaculiteor siliceous 

slate. In the Chippewa land district is found granite, gneiss, hornblende, chlorite, argillaceous slates, and magnetic iron ore. In Sec. 1, 

T. 46 K, E. 30 W., is a bed of quartz composed of rounded grains, with 

small specks of iron disseminated, and Iftrge rounded masses of the 

same material, inclosed, constituting a conglomerate. This bed is 15 

feet in thickness and is succeeded again by a specular iron exposed in 

places to the width of 100 feet.

The author is disposed to place the sandstone of lake Superior at the 

base of the fossilit'erous series. The imbedded traps of Keweenaw 

point and isleEoyale have broken through this sandstone, forming continuous lines of elevation. In receding from the trap of Keweeuaw 

point the inclination of the sandstone diminishes rapidly, and 5 or 6 

miles away is nearly horizontal. In a fork of Torch river, on the Bonglass Houghton mining company's land, the sandstone dips southerly, 

or away from the trap. On the north side of the stream it is seen resting on the trap in large blocks. On the south side of Keweenaw point, 

at Bete G-rise bay, the sandstone is white and granular, destitute of 

pebbles, and dips southerly or away from the trap. In the bottom of 

the bay, when the water is calm, the bands of sandstone can be seen 

describing immense curves parallel to the direction of the Bohemian 

range of mountains, and affording conclusive evidence that their bearing and upheaval are due to the protrusion of the igneous rocks. On 

the east side of Sec. 14, T. 59 N., E. 29 W., the sandstone is nearly hori- 

^outal, although removed but a few miles from the trap.
78 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 88.

BUET 69 finds on Keweenaw point and along the south shore of lake 

Superior to the mouth of Carp river and in the Porcupine mountains 

five principal groups of rocks: Primary, Slates, Trap, Conglomerate, 

and Sandstone. With the Primary rocks are placed syenite and granite. Flanking the Primary rocks is argillaceous slate; flanking the 

slates and resting upon them are red and variegated sandstones, and 

these also flank the Primary rocks. The Trap rocks have a much higher 

angle on the southeast than on the northwest side of the range, which 

runs from the northeast end of Keweenaw point and extends in. a course 

generally to the southwest. The Conglomerate flanks the trap range 

on the northwest, and is made up of sand, pebbles, and small bowlders 

principally derived from the rocks of the trap family. Besting conformably upon the conglomerate rock are a series of alternating strata 

of sandstone and conglomerate.

HUBBABD 70 finds, in the district south of lake Superior, Primary and 

Metamorphic regions, consisting of granite rocks, between which are 

metamorphic rocks which graduate into clay-slate.

BuET71 finds in the area bounded on the north by the Fifth Correction line and south by the Fourth Correction line and the Brule river, 

between ranges 23 and 37, granite and syenite, talcose and argillaceous 

slates, greenstone and hornblende-slate, mica-slates, coarse sandstone, 

calciferous sand rock, encrinal limestone, red sandstone and red clay, 

and magnetic iron ore beds.

FOSTER and WniTNEY,72 in 1850, give a systematic report on the 

geology and topography of the copper lands. On Keweenaw point these 

consist of trappean rocks associated with conglomerates and sandstones.

On this point are two trap ranges, the southern known as the Bohemian range. The conglomerates are volcanic friction rocks rather than 

the result of erosion. The pebbles may have received their rounded 

shape by being projected from fissures through water. The only instance in the district in which trap occurs remote from the lines of fissure 

is in the northeast corner of T. 49 K B, 36 W., where Silver mountain rises 

as an isolated and dome-shaped mass to the height of 1,000 feet. The 

summit of the rock consists of labrador and hornblende, while the surrounding plain is covered with clay, resting on sandstone in a nearly 

horizontal position. The sandstones and interbedded traps of Keweenaw point and isle Boyale dip in opposite directions and form a synclinal 

trough. Near L'Anse is a limited patch of limestone which has a dip 

to the eastward from 25° to 30°, the limestone being distinctly stratified. 

The sandstone about a quarter of a mile to the north is horizontal, and 

it seems evident that the limestone overlies the sandstone, although the 

position of the inclined beds of the more southerly portion of the limestone is difficult to explain, since the surrounding country is low and 

level and underlain by sandstone and horizontal beds. It seems evident 

that at this point the country has been disturbed and upheaved by 

igneous action beneath, which has raised the strata without any ap-
VANHI8E.] LAKE SUPEEIOR REGION. 79

pearance of trappeau rocks at the surface. This is indicated by the 

fact that at no great distance to the south an elevation occurs at which 

ILQ strata of sandstone dip on all sides, although there is no igneous 

ock visible. From the fossils entombed in this limestone Hall conmdes that the rocks may be regarded as the equivalent of any of the 

allowing: The Potsdam and Calciferous sandstones, the Chazy, Bird'seye, and Black river limestones, perhaps of the Trenton or even Hudson 

river groups. In T. 47 1ST., E. 25 W., Michigan, is a conglomerate, the 

pebbles of which comprise granite, hornblende, slate, greenstone, and 

iron ore.

FOSTER and WHITNEY", in 1851, report on the iron region of lake 

Superior land district, and give and an account of its general geology. 

The older rocks are classified as follows:

Of various ages.

^Feldspar and quartz rock.

Trappean ("Greenstone, or dolerite, porphyry, - basalt,

or I amygdaloid, hornblende and .serpentine

volcanic ] rocks, masses of specular and magnetic

rocks. [ oxide of iron.

( Gneiss, mica and hornblende slate.

Azoic system... < Chlorite, talcose and argillaceous slate. 

(_ Beds of quartz and saccharoidal marble.

Silurian system.

The igneous rocks are found in all these sedimentary systems. The 

oldest igneous rocks, consisting of hornblende, feldspar, and serpentine rocks are contemporary with the Azoic system. The granites and 

syenites are intermediate in age between the Azoic and Silurian systems. 

These are traversed by two systems of greenstone dikes which are 

anterior to the purely sedimentary deposits. Contemporaneous with 

the lower portion of the Silurian system are the bedded traps and 

amygdaloids of Keweenaw point, isle Boyale and the Ontonagon region, 

which are composed of nearly the same constituents as many of the 

older igneous rocks, although there is no difficulty from the diversity 

in external characters in drawing the line of demarcation between 

them.

Below all the fossiliferous groups of the region is a class of rocks consisting of crystalline schists, beds of quartz, and saccharoidal marble, 

which is denominated the Azoic system, a term first applied by Murchison and de Verneuil to designate the crystalline masses which preceded the Paleozoic strata. This term as here used is limited to rocks 

which are detrital in their origin and which have been formed before
80 PRE--CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

the dawn of organized existence. The general section shows the rocl?"- 

of Keweenaw point to be the counterpart of those of isle Boyale, excei 

that the dip of the sedimentary rocks is reversed, thus rendering 

highly probable that between these two points is a great curvafr 

in the strata caused by the elevation along the line of two volca 

fissures. The sandstone on the southern slope of the axis, equival 

to the Potsdam, is seen dipping away from the crystalline trap at' 

high angle, but at a short distance from the line of igneous outbr'-st 

it verges toward horizontality; and along the coast at the head of 

Keweenaw bay it is seen reposing uuconformably on the slates of the 

Azoic system. From L'Anse to Ohippewa' island in the Menomince 

river, a direct distance of more than 80 miles, the country is occupied 

by rocks of the Azoic system, which include immense deposits of specular and magnetic oxide of iron, and are invaded at many points by 

igneous rocks, both granitic and trappean. At Ghippewa island the 

Potsdam sandstone reposes upon the upturned edges of the slates.

The Azoic rocks have been so transformed by direct and transmitted 

heat as to exhibit few traces of their original character. Sandstone has 

been converted into massive quartz, limestone into saccharoidal marble, 

and shales into hard crystalline schists. These rocks are destitute of 

life, are a system of obscurely stratified rocks interposed between the 

Potsdam and the granite, and are unconformable to the former in dip. 

The Azoic series of the southern shore have not been capable of division into two groups as done by Logau on the north shore. The 

rocks are highly inclined and much contorted, and nowhere exhibit the 

characters of a purely sedimentary rock; but the evidences of metamorphism are more striking in approaching the lines of igneous outburst. Gneiss generally flanks the granite, succeeded by dark masses 

of hornblende, with numerous joints, but obscure lines of bedding, 

which often graduate into hornblende-slate or chlorite-slate in receding 

from the igneous products. The greenstones often form broad sheets, 

bearing the same relation to the slates that the trappean bands of Keweenaw point do to the conglomerates. Many of the slates appear to 

be composed of pulverulent greenstone, as though they might originally have been ejected as an ash and subsequently deposited as a sediment. They pass by imperceptible gradations from a highly fissile to a 

highly compact slate.

In Sec. 19, T. 49 1ST., E. 27 W., is found a talcose and chlorite slate, 

and quartzose rocks enveloping x>ebbles and displaying obscure lines of 

stratification. In Sec. 32, T. 48 N., E. 26 W., and near Jackson Company's forge are found quartzose conglomerates. On the line between 

Sees. 29 and 32, T.-47 N., E. 27 W., is a conglomerate forming an isolated 

rounded elevation, which is made up of coarse- blocks of various sorts 

belonging to the neighboring trappean and slaty beds. Among them 

are found fragments of the rock associated with iron, and masses of the 

iron itself, and of the banded and jaspery varieties. Most of the frag-
VANHISE.] LAKE SUPERIOR REGION. 81

-.ments of the breccia are but slightly-rounded and worn on their edges, 

laving in this respect the appearance of a Motion conglomerate. The 

locks are cemented together by a hard ferruginous paste. 

i:-The granites belong to £wo different epochs: That of the nortliwestrn coast and the vicinity of Pigeon river was elevated before the Azoic 

^riod, since the upper portion of the slates repose horizontally around 

c; while that of the northeastern coast, and that Avhich forms the axis 

o^ the river systems of the two lakes, was elevated after the termination 

of the ,Azoic x^riod and before the dawn of the Silurian, since th/j granite has disturbed the upper beds of slate, while the lower "'-^s of^tne 

Potsdam rest undisturbed aroundit\-. .. ' ^.,J)>. 

The masses of Iron ore and jasper have none of the characteristics of 

vein deposits. They-are intercalated among the metamorphosed sedimentark^ an&liave an intimate association:with the trappean, porphyritic, and serpentine rocks. If the trappean rocks were an invariable 

accompaniment, toe ores would with little hesitancy all be assigned to 

a purely eruptive origin; but when they are found in the form of beds, 

in^clearly metamorphic strata, having a common bearing and inclination, they are regarded as having been derived from the destruction of 

previously formed igneous masses, and their present association as having 

resulted from aqueous deposition. The Azoic period having been one 

of long continued and violent mechanical action, there is no reason to 

doubt that many of the strata of which it is composed* may have been 

derived from the ruins of previously formed rocks of the same age, both 

sedimentary and igneous, as is shown by the case of the knob of conglomerate already mentioned. The minute banding of the ore and 

jasper can hardly.be explained by any other than the action of segregating forces in an igneous rock. The authors are then disposed to 

regard the specular and magnetic oxide of iron as a .purely igneous 

product, in some instances poured out, in others sublimed, from the 

interior of the earth. Where the ores are in a state of purity, in the 

form of irregular masses in preexisting depressions, or where, the incumbent strata are metamorphosed or traversed "by the dikes of ferruginous matter, they are without doubt eruptive. Where impregnating 

metamorphic products, such as jasper, hornstone, or chert, quartz, 

chlonte, and talc slate, not only between the laminae but intimately 

incorporated with the mass, giving it a banded structure, they are 

regarded as the results of sublimation. The supposition that the ore 

may be a secondary product resulting from the decomposition of a" 

pyrite, or the inetamorphism of bog iron, is inadequate to account for 

the accumulation of such mountain masses and to explain the relations 

to the associated rocks.

, The bed of lake Superior, embracing an area of about 32,000 square 

miles, is occupied almost exclusively by the Potsdam sandstone. The 

sandstone in the vicinity of the trappean rocks attains the enormous 

thickness of 5,000 feet, and often consists of conglomerates composed 

Bull. 86 6
82 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

of trappean pebbles, and away from these lines of disturbance, where 

it abuts against the Azoic rocks, it is a purely siliceous sand. At 

Granite point masses of granite are overlain by horizontal sandstones. 

The granites are cut by dikes of green stoiie,Vhich in no case penetrate 

the overlying rock. The same phenomena are seen at Presque isle, at 

Middle island below Presque isle, and at Carp river. On the Menominee 

river, near the foot of Chippewa island; layers of sandstone are found 

on the upturned edges of the Azoic slates.

WLitney-d.oes not find the Pentamerm oblongus referred to by Jackson, no^- ~. e other form characteristic of the Niagara, formation;-but, on 

the oti- ^r fem'd, they are prononused as belonging to Lower Silurian 

types. - -^

FOSTEI? and WmTKEY,74 in 1851, repeat the^general ^conclusions 

contained in their report on the iron region, and remark that t\\& Azoic 

system is characterized by such immense deposits of specular and 

magnetic oxide of iron that it might with proprieVy'be denominated 

the Iron Age of geology, while the Silurian epoch with equal propriety 

might be designated the Copper Age.

FOSTER and WniTNEY,75 in 1851, farther speak of the age of the 

lake Superior sandstone. The sandstone of the St. Marys river is 

traced to the south shore of Keweenaw point and is found to increase 

in' thickness gradually, until in the vicinity of the trappean rocks it 

becomes of great thickness, accompanied by wide belts of conglomerate. The conglomerates of Ke ween aw point are the result of igneous 

rather than aqueous forces, being caused by friction and mechanical 

volcanic action along the line of fissure. The mural faces of the trappean ranges are almost without exception turned toward the south, 

and the sandstone on that side is elevated at a high angle, sometimes 

dipping almost vertical at the junction of the two formations, but in 

proceeding southward becoming almost immediately horizontal. The 

appearance is as if the strata had been broken and elevated just as the 

southern edge of the igneous mass. Where the sandstones and traps 

are interlaminated it* is difficult to determine the junction when the 

sandstone lies upon the trap, but when below it the line of separation 

is sharp. As further showing that the sandstone is Lower Silurian, a 

small deposit of Lower Silurian limestone resting upon the sandstone 

effectually completes the chain of evidence.

OWEN,76 in 1851, mentions various raetamorphic slates, quartzites, and 

other crystalline and trappean rocks as occurring on the south shore of 

lake Superior. On the north shore, in Minnesota, between Fond du 

Lac and the British possessions there is a repetition in inverse order of 

the same formations, forming a synclinal trough with the red sandstone 

nearest the lake, while the slates, conglomerates, and associated traps 

are crossed in succession in proceeding into the interior, and these are 

followed by the rnetamorphic slates and granitic rocks.
VANJIISK.] I,AKE SUPERIOR REGION. 83

OWEN,77 in 1852, discusses the age of the red sandstones of lake 

Superior. The test of "ithological character, if alone applied, is in favor 

of the view that they are of the same age as tlic red sandstones of New 

Jersey and Nova Scotia. On the St. (Jroix river, in Wisconsin, the 

white and buff qnartzose sandstones belonging lo the lowest Prqto/oic, 

formation are succeeded by red sandstones similar to those of lake Superior, and, like them, associated with coarse red. conglomerates and 

trap. The saute phenomena are seen at other points south of lake, 

Superior. It is, however, conceivable, as a result of the upthrust of 

igneous rocks, which sometimes break through the fossiliferous 

strata, entangling and partially indurating the fragments without altering or tilting the adjacent beds, that tilted red sandstones dipping 

to the south really may never rest conformably under the white and 

buff sandstones, but merely abut against them and not in fact overlie 

them at all; but the natural and reasonable inference is that the white 

and butt'sandstones do actually rest conformably upon the red sandstones in question.

NORWOOD,7" in 1852, gives a great number of details as to the geology 

of middle and western Minnesota and the country adjacent to the 

southwest shore of lake Superior, illustrating the relations of the shales, 

trap rocks, granites, etc., and showing the manner of intrusion of the 

eruptives and the complicated folding to which the strata have been 

subjected. At the St. Louis and Black rivers the sandstone rests 

uncon form ably upon the underlying argillaceous and siliceous slates.

WiiriTLESEY,7'' in 1852, gives geological descriptions of part of Wisconsin south of lake Superior. Passing from the lake southerly four 

great classes of rocks are seen in each section: (1) Sedimentary, including red sandstone, black slate, conglomerate. (2) Trappose rocks, or 

those of volcanic origin, including amygdaloid, greenstone, augitic, 

hornblendic, and feldspathic rocks, embracing syenites and granites ot 

the same age. (3) Metamorphosed rocks, including hornblende slates, 

iron slates, black slates, talcose slates, slaty quartz. (4) Granitic, including syenite and granite. The granites and syenites of the interior are 

the most ancient rocks of the district. After the protrusion of these 

granitic masses many changes harve occurred. The sandstone deposits 

of hike Superior must have been subsequent to the granites of the 

AVisconsin, Chippewa, and Montreal rivers; since that period has 

been one of long and intense igneous action in which the trap, hornblendic, and greenstone masses have been ejected, and also with them 

protrusions of recent granites and syenite. The metamorphic slates 

have been elevated during1 these convulsions, and the sedimentary 

rocks thrust away to the northward and tilted up at high angles. The 

old granites and syenites have been rent with lluid matter, such as 

quartz and. hornblende. The northern part of the Penokee range 

shows evidence of four formations of trappose rocks, which fill a geological epoch of no great duration between the area of the led sandstone
84 PRE-CAMBKIAN ROCKS OF NORTH AMERICA. [BULL. 86.

deposits and the metamorphic uplifts. There are cases where the trap, 

instead of being forced across the stratification, has spread out between 

the beds, forming alternate strata of trap and sandstone without any 

visible conglomerate.

SnuMARD,80 in 1852, mentions the quartzite ranges of Sank county, 

near Baraboo. The quartzites are surmounted by sandstone, and all 

are included in the great sandstone formation of southern Wisconsin.

JACKSON,81 in 1853, maintains that the red and gray sandstones of 

lake Superior are above the rocks of Devonian age. They rest horizontally around Silurian limestone, which has an inclination on Sturgeon 

river near Keweenaw point of 30°. In point of fact the sandstones of 

lake Sui>erior are the exact equivalents of those of Nova Scotia, where 

trap rocks of the same age as those of lake Superior pass through them. 

The arnygdaloidal trap of Keweenaw point and isle Eoyale is a vesicular rock formed by the interfusion of sandstone and trap rock.

MARCOTJ,82 in 1853, after having made a complete tour of lake Superior, places the red sandstone and traps bearing copper as the new red 

sandstone, and correlates it with the neAv red sandstones of Nova 

Scotia, New Brunswick, Connecticut, New Jersey, Maryland, and Virginia.

WniTNEY,83 in 1854, states that the basin of lake Superior is a great 

synclinal trough caused by a depression of the sandstone, which appears 

to form its bed. The northern and eastern shores for much of their distances are faced by perpendicular cliffs, while the southern shore is 

comparatively low. The reason for this difference is that on the east 

and north the sandstone which originally existed there has been worn 

away and the more enduring granitic and trappeau rocks only are left. 

The age and relations of the sandstones of lake Superior to the trappean rocks and Azoic slates are again described as before.

SCHOOLCRAFT, 84 in 1855, states that the granitic strata of the Thousand isles reappear on the north shore of lakes Huron and Superior, 

underlie the bed of the latter, and are found on the rough coast between 

Chocolate river and KeweenaAV, and cross the Mississippi near the falls 

of St. Anthony. The straits of St. Mary's appears to be the ancient 

line of junction between the great calcareous and granitic series of 

rocks on the continent. The island of St. Joseph is chiefly primitive 

rocks and at its South end is largely loaded with granitic, porphyritic and 

quartzitic bowlders. The north shore of the river, opposite the island, 

is entirely of the granitic series, which continues to Gros cap on lake 

Superior. The red sandrock of lake Superior is regarded as the Old 

Eed sandstone. The formation of red jasper in white quartz exists on 

the southern foot of Sugar island. In the granitic conglomerates are 

seen red feldspathic granite, black shining hornblende rock, whitefatty 

quartz, and striped jasper, all held together firmly. Volcanic action 

appears to have thrown up the trap rocks of the Pic, of the Porcupine 

chain, of isle lioyale, and the long peninsula of Keweenaw. The sand-
YAKUTSK.-] LAKE SUPERIOR REGION. 85

stone of the southern coast exhibits unclnlations of 8° or 10° at several 

places. Two instances of this are the point des Grands Sables, beginning with the horizontal strata of the Pictured rocks, and the second is 

at Grand island.

WniTNEY,85 in 185C, describes the northeastern side of lake Superior, 

from Gros cap to Nipigon bay, as consisting of rocks of the Azoic system. 

On the south shore of the lake, and along the northwest shore as far as 

the northeastern extremity of Nipigon bay, are found the shales, sandstones, conglomerates, and trappean rocks of the Potsdam system, except at Thunder bay and Carp river, where the Azoic appears. The south 

side of the Azoic on the north side of the lake runs from Kakabikka 

falls on the Kainhristiqnia in an almost straight line southwest, keeping a 

few miles from the lake. Thunder cape consists of thinly bedded slates 

for 800 feet of its thickness, above which is a sheet of trappean rock 

200 or 300 feet thick.

WniTNEY,86 iii 1856, maintains that the iron ores of lake Superior, 

Scandinavia, Missouri, and northern New York, form a class by themselves belonging to the Azoic age, and they have been poured out like 

other igneous rocks from the interior in a molten or plastic state. 

Besides the purest ores are others interlaminated with bands of quartz 

which are distinctly bedded and probably are of sedimentary origin. 

The iron ore in these may have been introduced either by sublimation 

during the deposition of the siliceous particles, or by precipitation from 

a ferriferous solution at the time of formation of the stratified rocks.

WniTNEY,87 in 1857, again maintains the Potsdam age of the sandstones of the Cupriferous series. Underlying this series un conformably on the south shore is the Azoic series, which is identical in character with the rocks of Thunder and Black bays. The rocks on the 

north shore of lake Hiiron and in the north and east of Canada are 

identical in position and lithological character with the Azoic system.

JACKSON,88 in 1860, again asserts that the red sandstones of Keweenaw point are certainly coeval with the sandstone of Nova Scotia, 

Connecticut river, and New Jersey, as proved by identity of composition, mode of disruption, character of associated minerals, and above 

all, by the fact that they rest upon Devonian limestones. OrtkoceraUto 

at Copper Falls mine and Pentamerus in the underlying limestone of 

Sturgeon river show that the sandstones are not Potsdam. This is also 

shown by the occurrence of pitch stone porphyry upon isle Eoyale such 

as are found in the isle of Arran of Triassic or Devonian age. The 

author is not disposed to place the sandstones of the Pictured rocks in 

the same formation with Keweenaw point a.nd isle Eoyale.

EoGERS,"9 in 1860, maintains that the argillaceous shales and conglomerates of a part of the southern shore of lake Superior are the 

equivalent of the Primal series. The Cupriferous series is in direct 

association with the Potsdam, and therefore the argument for Triassic 

age on account of texture and color is entirely valueless.
86 PRE-CAMBRTAN ROCKS OF NORTH AMERICA. [BTJLT, 86.

WILLIAMS and BLANDY,90 in 1862, describe the trap range's, of Portage lake as being about 3 miles wide and consisting of amygdaloidal 

trap, occasionally intercalated with sandstones and conglomerates. 

The dips vary from 60° to 75°^ becoming nearer horizontal toward the 

northwest, until finally the sandstone which succeeds it becomes absolutely so.

KiMBALL,91 in 18G57 divides the rocks of the Marquette region into 

two formations, Laurentian and Huronian; the former including the 

granite ridges, while the latter nearly agrees with Foster and Wliituey's 

limits for the Azoic. The crystalline rocks south of Keweenaw point 

are pre-Paleozoic, while the greenstones of that point are intercalated 

conformably with the Paleozoic. The specular iron ore and beds of 

specular conglomerate are heavy bedded strata and schists in which 

none of the phenomena of aqueous deposits are wanting. They exhibit 

not only stratification, but anticlinal and synclinal folds. From a 

stratigraphical point of view the Huronian greenstones, schists, and 

iron ores of Marquette exhibit characters which render quite untenable 

the theory of the exotic character of any portion of them.

AdAS.Siz,92 in 1867, finds at two ravines near Torch lake one the 

Douglass Houghton that the sandstone rests uuconformably upon 

the trap. The trap dips K". 42°, while the sandstone, 100 feet distant, 

lies nearly horizontal, with no trace of an anticlinal axis between.

The sandstone contains water-worn fragments of the trap. The sandstone north of the range is conformable with the trap, but the sandstone 

south is plainly of a different age.

WHITTLESEY,9:! in 1876, finds nowhere on the American side of the 

boundary, except at Vermilion lake, rocks which are like the Laurentian 

of Canada. The great masses of granite and syenite around which the 

Hnroiiiun is formed do not resemble the Laurentian of the Canadian 

geologists. Between the Canadian and American Huronian there is a 

very close resemblance. The conclusion of Foster and Whitney that the 

traps of lake Superior are of Potsdam age is adopted. The Bohemian 

range resembles more nearly the Huronian than it does the trap series. 

In this range are bands of friction conglomerates with the evidences of 

metamorphic sandstone passing into jasper, vesicular trap, and breccia.. A friction conglomerate also occurs at Aininicon, Douglas county, 

Wisconsin.

WABSWORTii,94 in 1880, gives notes on the geology of the iron and 

copper districts of lake Superior. The contacts of the jasper and ore, 

which are interlaminatcd and have a common origin with the associated schists, are described, and at numerous points the contacts are 

found to be those of eruptive and sedimentary. The schistose structure is regular, while the jasper and ore is exceedingly contorted, breaks 

across the schistose and other rocks, and contains fragments of the 

schists. Not the slightest sign of plasticity or intrusion of the schists 

relative to the ore and jasper was seen. The present lamination of the
VAXHISE.] LAKE SUPERIOR REGION. 87

schists existed prior to the intrusion of the ore. At the School-house, 

New York, and Jackson mines the overlying rock contains de"bris of 

the underlying ore and jasper. The diorites, felsites, and diabases are 

intrusive rocks. The soft hematites differ only from the hard ore and 

jasper in that they have been leached by thermal waters and changed 

to their soft condition. The granite is found at numerous points to cut 

the schists and gneisses. At several places, also, it cuts a quartzite, 

one of which resembles the ordinary Huronian quartzite. The crystalline rocks of Presque isle are peridotite and serpentine which has resulted from the alteration of the peridotite.

The only evidence that the Huronian unconformably overlies the 

Laurontian is the fact that the foliation of the latter does not conform 

in its dip to that of the former. However, no point was found in which 

it was possible to trace the rock continuously from well marked and 

mapped Laurentian into the Huronian. The general structure of the 

iron region seems to be as follows: The schists and sandstones were 

laid down in the usual way; were then disturbed by the eruption of the 

jasper and ore. Much of the original rock still remained horizontal, 

and new sedimentary deposits continued to be formed out of the jasper 

and other rocks. Next came the eruption of the diorite, which completed most of the local folding and tilting of the strata. Finally the 

granite eruption took place on both sides of the Huronian, uplifting and 

contorting the strata near it, and perhaps laterally compressing the 

inclosed iron-bearing rocks.

The conclusion reached by Foster, Whitney, and Marvine that the 

traps and lava, flows and were successively laid down one upon the 

other, are covered by sandstones and conglomerates, is agreed \vith. 

The sandstones and conglomerates when overlain by traps are usually 

baked and indurated. At the Douglass Houghton ravine and Hungarian river the eastern sandstone, which. h*as been maintained to rest 

against the trap and sandstone series unconformably, is found interlaminated with the melaphyres, and therefore settles the long-disputed 

question of the relative age of the traps and Eastern sandstone of lake 

Superior. The last melaphyre sheet which underlies the sandstone has 

a dip to the northwest of 20°. As the Douglass Houghton ravine is 

followed downward the dip gradually declines in steepness, although 

still to the northwest, the last dip measured being 5°. The junction 

between the Eastern sandstone and the trap., described by Agassiz and 

Pumpelly, is not the junction at all, it being some distance below instead of at the falls. In the Torch lake sandstone quarry the sandstone 

layers, instead of being horizontal as they have been regarded, have a 

dip of 15°, the former supposed bedding being due to joints. As the 

Eastern sandstone conformably underlies the traps, the Eastern and 

"Western sandstones and the traps lying between them are of the same 

geological age.
88 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 80.

WADSWORTH, 95 in 1884, as a result of an examination of a supposed 

fossil from the copper-bearing rocks of lake Superior, described by Hall 

as being very like the Huronia or siphuncles of Orthoceratites, finds it 

to be of inorganic origin, having probably been formed by the flowing 

of a pasty lava in such a manner as to raise a series of ridges, giving an 

appearance closely like that of some cephalapods. The interior of the 

specimen is in all respects that of an ordinary volcanic rock.

SECTION III. WORK OF THE MICHIGAN GEOLOGISTS AND ASSOCIATES.

HouGHTON,96 in 1840, divides the rocks in the south and southeastern 

part of the Upper Peninsula into primary and sedimentary. The 

primary region stretches continuously in a northwestward direction for 

many hundreds of miles, skirting portions of the shores of lake Superior, and constituting the highlands between that lake and the lake of 

the Woods. From these highlands it stretches a little east of lake 

Winnipeg, far to the northwest, finally constituting the immense " barren grounds" of the British Possessions. The rocks of St. Marys river 

and adjacent region comprise greenstone, argillite, and granular quartz 

rock, which passes into an almost conglomeratic quartz rock. In this 

occur small quantities of hematitic iron ore. The sedimentary rocks 

include the lake Superior sandstone and lime rock and shales. The 

lake Superior sandstone is nearly continuous on the southern shore of 

lake Superior, and in its easterly prolongation rests against and upon 

the primary range of St. Marys river, where it passes. conformably 

below the limestone above. The lake Superior sandstone, in its easterly prolongation, does not attain a very great thickness, but in proceeding westerly this thickness is vastly increased, attaining on the 

south shore of lake Superior to several hundred feet. A careful search 

for fossils in this sandstone has failed to reveal a single one.

HouGHTON,97 in 1841, divides the older rocks of the upper peninsula 

of Michigan into (1) Primary, (2) Trap, (3) Metarnorphic, (4) Conglomerate, (5) Mixed conglomerate and sandstone, (G) Lower or red 

sandstones and shales, (7) Upper or gray sandstone. The Primary 

rocks are in a broad sense granite. The granitic rocks are largely 

traversed by greenstone dikes. The trap rocks of the district in a 

chronological order would follow the metaniorphic slates and quartz 

rocks, but the granitic rocks pass by almost insensible gradation into 

the greenstones of the trap formation.

The sedimentary rocks on the south and southeast of the main trap 

range are scarcely disturbed, while those on the north and northwesterly sides are invariably tilted to a high angle near the range of hills. 

The sedimentary rocks on the north are traversed by frequent dikes, 

varying in thickness from 50 to 400 or 500 feet. The rocks on this 

northwestern escarpment were in an intense state of ignition while in 

contact with the sedimentary rocks, as shown l)y the great changes 

which these rocks have undergone. The author is disposed to regard
VANHISE.] LAKE SUPERIOR REGION. 89

the amygdaloid as due to the fusion.of the lower portions of the sedimentary rocks.

At Presque isle is a little isolated knob of trap which has been uplifted, as is shown by the way in which the stratification of the adjacent 

sedimentary rocks has been disturbed. They invariably dip at a high 

angle in all directions from the trap. At the immediate line of junction 

the character of both rocks is lost, and the sedimentary rocks for a 

distance of several hundred feet have been shattered while retaining 

their original position, and were again cemented by an injection of calcareous matter.

The area of country occupied by the metamorphic group is less than 

by the Primary or Trap. The group is made up of an alternating series 

of talcose and mica-slates, graduating into clay-slates, with quart/ and 

serpentine rocks, the quartz rocks being by far the most abundant. 

The metamorphic rocks are occasionally traversed by trap dikes.

The conglomerate rock, the lowest of the sedimentary rocks, is invariably connected with or rests upon, the trap rock. It is very variable 

in thickness and is without doubt a trap tuff which has accumulated or 

deposited around the conical knobs of trap during their gradual elevation. The pebbles of the rock consist of rounded masses of greenstone 

and amygdaloid. They are usually firmly cemented by calcareous and 

argillaceous material. Resting conformably upon the conglomemte is 

a mixed conglomerate and sandrock. This mixed rock occurs upon 

isle Hoy ale and was seen to be very widespread upon the south shore. 

The conglomeratic part of the mixed rock has the same character as the 

conglomerate rock. Dikes of greenstone are found in this mixed rock, 

but less frequently than in the rock below. The red sandstone is the 

chief rock that appears upon the immediate coast of the south shore of 

lake Superior. The primary, metamorphic, and trap rocks are almost 

invariably surrounded or flanked at their bases by this sandrock. The 

material of this sandrock differs widely from the conglomerate rocks, 

for these are, made up of materials clearly of trappean origin and very 

rarely of quartz; while the red sandstone is composed of materials derived from the granitic and metamorphic rocks, in which quartz occurs 

abundantly. The red sandrock is less frequently traversed by dikes 

than the rocks before described, although they are sometimes noticed 

traversing the whole of the several rock formations, including the red 

sandstone. The upper or gray sandrock conforms to the limestone 

above it, and rests conformably upon theuptilted edges of the red sandrock below.

WIKOHELL (ALEXANDER),98 in 1861, gives a general sketch of the 

geology of Michigan. Among the stratified rocks are placed the Azoic, 

while the unstratified rocks are divided into Volcanic, includin g lava, trap, 

etc., and Plutonic, including granite, syenite, etc. The Azoic rocks are 

of immense thickness and are interposed between the crystalline, pi utonic, 

and volcanic rocks and the lake Superior sandstone. The rocks in
90 PEE-CAMBETAN EOCKS OF NOETH AMEEICA. [BULL. 86

this system in Michigan consist of talcose, chloritic, and siliceous slates, 

quartz, and beds of marble. In it are found the specular and magnetic 

ores of lake Superior. The Lake Superior sandstone is placed in the 

lower Silurian system. The solid quartzose character of the rock of 

St. Joseph's and Sulphur islands suggests the idea of its being Azoic5 

but the gradual transition from the unaltered sandstone of the Sault 

to the altered sandstone of Keebish rapids and jasper conglomerates of 

the western shore of Campement d'Ours, favors the idea of the equivalency of the sandstone and quartzite, as it is also the fact that the fossiliferous Chazy limestone is found directly upon the quartzite at Sulphur island.

CREDNER," in 1869, describes in the upper peninsula of Michigan the 

Laurentian and Huronian systems. The Laurentian system is the 

gneiss-granite formation, which includes many varieties of massive 

rocks, as well as hornblende, chlorite, and other schists, and also thin 

layers of dolomitic limestones.

The Huronian system is the iron-bearing formation. The general 

succession, beginning at the base, is quartzite, in its upper parts often 

iron stained, 2,500 feet; crystalline dolomitic limestone, containing 

argillite, chlorite-schist, and layers of quartz, seldom conglomeratic, 

2,500 to 3,500 feet; more or less siliceous hematite, 600 to 1,000 feet; 

ferruginous chlorite-schist, 1,200 feet; dark clay-slate, with beds of hard 

quartzite, 8,500 feet; chlorites-chist, with beds of diorite, 1,300 feet; 

talc-schist, with various impurities, 100 feet; aphanitic to granular diorite, 2,300 feet; talc-schist, with various impurities, 1,500 feet.

In the iron group is a granite dike on the Sturgeon river 12 feet wide, 

which breaks through the iron ore and jasper at a right angle to the 

schist. Over the iron formation, at the Michigainme mine, is found a 

conglomerate of jasper and fragments of quartz in an iron and quartz 

base. There is a discordance between the Laureutian and Huronian. 

The Potsdam sandstone rests upon the Hurouian and Laurentian unconformably.

BROOKS and PUMPELLY,IO° in 1872, maintain that the copper-bearing 

rocks of lake Superior are unconformably below the Lower Silurian 

sandstone. This is shown by the fact that the horizontal strata abut 

against the steep faces of the cupriferous series on Keweenaw point, 

the latter dipping away from the sandstone at an angle of from 60° to 

40°. Also for a long distance between the Montreal river and lake 

Gogebic the cupriferous series conform in strike and dip to the Huronian schists, dipping steeply to the north at an angle of from 50° to 70°, 

while the Silurian sandstone to the north, in a flat-lying condition, covers an extensive country. In Sec. 13, T. 46 N"., E. 41 W., the Silurian 

sandstone is found in a nearly horizontal position, while 4 miles distant 

the cupriferous series dip to the north at an angle of 50°.

It is concluded that the cupriferous series was formed before the tilting of the Huronian beds upon which it rests conformably, and conse-
VAN HISS.] LAKE SUPERIOR REGION. 91

quently before the elevation of the great Azoic area. After the elevation of these rocks, and after they had assumed their essential lithological characters, came the deposition of the lake Superior sandstone and 

its accompanying shales as a product of the erosion of the older rocks, 

and containing fossils which show them to belong to the Lower Silurian. 

At several places have been detected alack of conformity between the 

Laurentian and Hurouian in the upper peninsula of Michigan, but when 

the Huronian and Cupriferous are seen in contact there seems to be a 

well marked concordance between them.

BROOKS, 101 in 1873, divides the rocks of the upper peninsula in descending order into Lower Silurian, Copper-bearing rocks, Iron-bearing 

rocks, and Granitic rocks, and gives a systematic account of the last 

two, and especially of the economic geology of the iron-bearing series. 

The copper-bearing rocks correspond Avith the Tipper Copper-bearing 

rocks of the Canadian geologists and occupy a narrow belt on the northwestern edge of the upper peninsula. This series includes sandstones, 

which are nearly or quite identical with the Silurian in appearance, but 

their great mass is made up of different varieties of trap, often amygdaloidal, interstratified with beds of peculiar conglomerates. The layers of these rocks are inclined, dipping northwest and north toward 

lake Superior, from vertical to as low as 23° on Keweenaw point. The. 

iron-bearing rocks are assumed to correspond with the Hurouian system 

of Canada. They may have a thickness of 5,000 feet and consist of a 

series of extensively folded beds of diorite, quartzite, chlorite-schists, 

clay-slate, mica-slate, and graphitic shales, among which are intercalated extensive beds of several varieties of iron ore. The most abundant rock is greenstone or diorite, in which the bedding is usually obscure, but the intercalated schists and slates usually bear strong marks 

of stratification. The dips are usually at a high angle and are more 

apt to be north or south than any other direction.- t The granitic, rocks 

are believed to be the equivalents of the Lanrentian of Canada.. In 

these the bedding indications are still more obscure and often entirely 

wanting. Also, if possible, there is more irregularity in strike and dip 

than in the Huronian.

A full lithological description of the different phases of rocks found 

in the Huronian system, and the various sections at the many mines in 

the upper peninsula are given in detail.

The formations of the lluroniau system in the Marquetteregion comprise nineteen members, n umbered from the base upward. I, II, HI, and 

IV are composed of beds of siliceous ferruginous schist, alternating with 

cMoritic schists and diorites, the relations of which have not been fully 

made out; V is a quartzite, sometimes containing marble and beds of 

argillite and novaculite; VI, VIII, and X are siliceous ferruginous 

schists; VII, IX, and XI are dioritic rocks, varying much in character; 

XIII is the bed which contains all the rich specular and magnetic ore, 

associated with mixed ore and magnesian schist; XIV is a quartzite,
92 PRE-CAMBRIAN ROCKS OF NORTH AMERICA.. [Buu,86.

often conglomeratic; XV is argillite or clay slate; XVI is uncertain, 

it contains some soft hematite; XVII is anthophyllitic schist, containing iron and manganese { XVIII is doubtful; XIX is mica-schist, containing stanrolite, andalnsite, and garnets. The total thickness of the 

whole Marqnette series may have an aggregate of 5,000 feet.

The beds appear to be metamorphosed sedimentary strata, having 

many folds or corrugations, thereby forming in the Marquette region 

an irregular trough or basin, which, commencing on the shore of lake 

Superior, extends west more than 40 miles. The upturned edges of 

these rocks are quite irregular in. their trend and present numerous outcrops. While some of the beds present lithological characters so constant that they can be identified wherever seen, others undergo great 

changes. Marble passes into quartzite, which in turn graduates into 

novaculite.

Near the junction of the Huronian and Laurentian systems, in the 

Marquette region, are several varieties of gneissic rocks, composed in 

the main of crystalline feldspar, with glassy quartz and much chlorite. 

Intersecting these are beds of hornblendic schist, argillite, and sometimes chloritic schist. These rocks are entirely beneath all of the iron 

beds, seem to contain no useful mineral or ores, and are of uncertain 

age. No attempt is here made to describe or classify them.

The diorites, dioritic schists and related rocks range in structure from 

very fine grained or compact (almost aphanite) to coarsely granular 

and crystalline, being sometimes porphyritic in character. The rock 

passes on the one hand into a hornblende rock, and on the other into a 

rock resembling a diorite. It is eminently schistose in character, splitting easily, and appearing more like chloritic schist than any other 

rock. At several points dioritic schists, semi-amygdaloidal in character, were observed, and in one instance the rock had a strong resemblance to a conglomerate. The bedding of the rocks is generally obscure 

and sometimes entirely wanting. It is only by a full study of the rock 

in mass and its relations to the adjacent beds that one becomes convinced, whatever its origin, that it presents in mass precisely the same 

phenomenon as regards stratification as do the accompanying schists 

and quartzites. Chloritic magnesian schists are associated with the 

pure and mixed ores. Oftentimes these magnesian schists several feet 

in width cut across the stratification and are called slate dikes. It is difficult or impossible to draiv the line between these magnesian schists 

and the dioritic schists. It is suggested that on the New England-Saginaw range and at the lake Superior mine, tepid alkaline waters have 

penetrated the formation and have dissolved out the greater portion of 

the siliceous matter, leaving the iron oxide in a hydrated earthy condition.

At the S. 0. Smith mine and along Plumbago brook is found carbonaceous matter. These carbonaceous shales burn white before the blowpipe and mark paper like a piece of charcoal.

Above the Cascade ore is a bed of coarse conglomerate. The uppfer
VANHISE.] , LAKE SUPERIOR REGION. 93

quartzite of Republic mountain, near'its base, is a conglomerate contaiuing large and small fragments of flaggy ore. At the New England 

mine between the ore and the quartzite is a mass of specular conglomerate ^imilar to that at Republic mountain.

The iron-bearing series is unconformably above the older Laurentian 

rocks. The contact is observed in Plumbago brook, where a talcy red 

rock, unmistakably belonging to the Huronian, dipping at a low angle 

to the northwest, is in contact with the Laurentian chloritic gneiss, 

which dips at an angle of about 35° SSW. The same' phenomena can 

be seen near Eepublic mountain, where the Huronian schists strike 

nearly at right angles to the Laurentian gneiss only 5.0 feet distant; 

both series dipping at high angles, the Laurentian east of north, and 

the Huronian about 45 degrees west of north. The non-conformability 

is further shown by the fact that the Laurentian generally abounds in 

dikes of granite and diorite, which are almost entirely absent from the 

Huronian.

Many details are given as to the Menomiuee and Felch Mountain 

districts. The rocks of these ranges are parallel with those in the 

Marquette district. At many places the Silurian rocks unconformably 

cap the iron-bearing rocks.

The lake Gogebic and Montreal river iron range is regarded as an 

eastern prolongation of the Penokee range of Wisconsin. The northern 

geological boundary is the south copper range, consisting of massive 

and amygdaloidal copper-bearing traps, the bedding of which is exceedingly obscure, with occasional beds of sandstone and imperfect conglomerates. The strike of these rocks is east and west, with a dip to 

the north at a high angle, thus conforming with the Huronian rocks 

underneath. On the south of the iron-bearing rocks is a series of 

granites, gneisses, and obscure schists, which are unmistakably Laurentian in their lithological character, and they are unconformably 

overlain by the Huronian rocks. The horizontal Lower Silurian sandstones occupy a broad belt of country north of the copper range. Their 

actual contact with the highly tilted copper rocks was not seen, but 

they show not the slightest evidence of disturbance within a few miles 

of these steeply inclined rocks, and are regarded as unconformably above 

them.

PuMPELLY,102 in 1873, gives a systematic account of the copperbearing rocks. These on Keweenaw point consist of an immense development of alternating trappean rocks and conglomerates dipping to the 

northwest at an angle running from 60° to 23°. The red sandstone and 

shales of lake Superior are everywhere nearly horizontal on the south 

shore of lake Superior between the Sault Ste. Marieand Bete Grise bay. 

At the western edge of this belt its nearly horizontal strata abut against 

the steep face of a wall formed by the upturned edges of beds of the 

cupriferous series of inelaphyre and conglomerate, which dip away from 

the sandstone at angles of from. 40° to 60°. This sharp line has been
94 PRE--CAMBRIAN ROCKS OF NORTH AMERICA. [BULL.86.

explained as due to a fault, the'horizontal sandstone being regarded as 

of the same age as the conformable overlying sandstone of the cupriferous series. One objection to this explanation is the enormous amount 

of dislocation required, amounting to several miles. Again,near Houghton there are t\vo patches of sandstone lying on the upturned nielaphyre 

beds; In the horizontal sandstone near the so-billed fault are abundant 

pebbles of melaphyre and conglomerate of the cupriferous series. But 

the most decided facts found by Maj. Brooks and the author are in the 

country between the Bad river in Wisconsin and the middle branch of 

the Ontonagon, east of lake Gogebic. Here the quartzites and schists 

of the Huronian formation are bordered on the south by the Laurentiau 

gneisses, and are overlain conformably by the bedded melaphyres and 

interstratified sandstones of .the cupriferous series. Between these 

ridges forming the south mineral range and the main range of Keweenaw point is the horizontally stratified Silurian sandstone, forming 

a generally level country. The conformable cupriferous and Huronian schists dip to the northward at angles from 50° to 70°, but in approaching Gogebic- lake from the west the pre-Silurian erosion has made 

a deep indentation across the cupriferous series and the Huronian, as 

well as into the Laurentian, so that a short distance west of the lake 

these rocks end in steep and high declivities, at the base of which 

lies the level country of the Silurian sandstone. On the Ontonagou 

river the Silurian sandstone is nearly horizontal, while about 150 steps 

from the base of the cliff are outcrops of Laurentian schists having a 

dip of 45° to 00° southeast. The nearest outcrop of the cupriferous 

series is about 4 miles distant, and it strikes nearly east and west and 

dips 50° to the north. The lithology of the copper-bearing rocks of the 

Portage lake district is fully given. The rocks are melaphyres and 

atnygdaloids, interstratined with conglomerates. The paragenesis of 

the minerals associated with the copper is worked out. Several 

detailed cross sections are given at Portage lake, and one cross section 

at the Central mine describing the thickness and character of the 

alternating rocks in great detail.

MAnviNE,103 in 1873, gives in the greatest detail the structure and 

lithology of the alternating trappean and detrital beds of the copperbearing rocks on the Eagleriver section. The correlation of the Houghton and Kewcenaw rocks is fully discussed. The Albany, Boston, and 

Allouez conglomerates are regarded as the sa me bed. Stratigraphically 

eleven out of fifteen conglomerates have equivalents in both the Houghton and Keweeuaw regions. The conglomerate beds of KeweenaAv 

point are not mere local deposits, but.are unusually persistent, and 

while a bed may thin out and lose its character as a conglomerate, it 

may still exist as a mere seam. In one instance a band extends for 

at least 50 milos, varying in thickness from a few to over 75 feet. It 

is therefore concluded that the changes which formed the rnelaphyres
VANIUBB.I <LAKE SUPERIOR REGION. 95

ceased to act over extended areas during the time of the formation of 

the sandstones and conglomerates. The abundance of acid rocks among 

the conglomerates was noted, and opposite Calumet the former prgsence of predominant quartz-porphyry was inferred.

ROMINGER, 104 in 1873, places the lake Superior sandstone as Potsdam, 

finding it directly overlapped by the calciferous formation. At Presque 

isle and Granite point the horizontal sandstones are found resting 

upon the crystalline rocks, there being at the former place a conglomerate which rests unconformably upon the dolomite of Presque isle. 

The sandstones on the eastern shore of Keweenaw point retain their 

horizontal position and lithological character to such a degree that the 

different strata can be parallelized without difficulty with those of the 

more eastern localities. Near the center the horizontal sandstones are 

found abutting against the uplifted edges of a different rock series, the 

copper-bearing rocks. The abrupt edges of the strata look to the southeast, and their clip is in the opposite direction under angles varying 

from 70° to 40°. The unconformable abutment of th^e sandstones against 

the trappean series is plainly observed at several places near Houghton, 

on the property of the Isle Royale company, near the stamp works of 

the Calumet and Hecla mines, on the railroad coming down from the 

mines to the stamp works, and on the Sheldon and Columbia property.

KoMiNGER, 105 in 1870, describes the red lake Superior sandstone as 

unconformably abutting against or overlapping the trap rock with horizontally disposed layers. On the western slope of the ridge the trap 

rocks are conformably overlain by sandstones, conglomerates, and slates, 

the age of which is intermediate between the trap and the horizontal 

sandstone, butbetween all three there are such great lithological affinities 

that it is natural to regard them as consecutive products of one and 

the same epochs. The absence of trappean rocks distinguishes the 

upper division from the lower.

The Huron mountains are a crystalline granitic and dioritic Laurentian rock series. These granitic rocks are surrounded by a narrow belt 

of the horizontal red sandstone of lake Superior, which abuts uuconformably against theni. The Huronian rock series, with uplifted beds 

alternating with slate rocks, quartzites, diorites, and jaspery strata, 

with seams of iron ore, lean unconformably against the granitic series.

BROOKS, 1UG in 1870, places granite as the youngest Huronian rock 

south of lake Superior. This granite occurs as the uppermost member of 

the Menominee and Penokee series, but in the latter it thins out and disappears before reaching the Gogebic region. The lithological character 

of this granite belt bears .a general resemblance to the Laurentian 

rocks. This granite, from the fact that it does not give off dikes cutting the copper-bearing series, is believed to be earlier than the latter. 

Although there is approximate conforinability in strike and dip, there 

is probably an unconformity between the copper-bearing rocks and the
96 PRE-CAMBRIAN ROCKS OF NORTH 'AMERICA. [BULL.80.

Peuokee-Gogebic Huronian, as shown by the fact that the former series 

is in contact in different places with various members of the Huronian. 

T^ere is also an unconformity between the Huronian and Laurentian.

As supporting the view that the pre-Silurian systems are distinct 

periods, attention is called to the lithological differences between the 

three series, as well as to the intensity of folding to which they have 

been subjected. The detrital members of the copper series consist of 

friable sandstone showing no greater metamorphism than the Silurian, 

and it is folded only in regular magnificent sweeps, the same strike and 

dip continuing in some cases for about 150 miles. The Huronian series 

consists of greenstones, various schists, clay-slates, quartzites, marbles, 

with gneisses and granites containing no copper, and having conformable beds of the various oxides of iron, and is everywhere sharply folded 

into narrow troughs and irregular basins trending in every direction. 

The Laurentian is still more plicated and metamorphosed, the stratification often being entirely obliterated. Whether the Laurentian rocks 

can be separated into two or more nonconformable systems, as in 

Canada, no opinion is ventured. Since Keweeuaw peninsula is a striking geographical feature in lake Superior, and is the locality Avhere the 

copper series is best exposed, the name Keweenawian is suggested for 

this period.

BROOKS107, in 1876, gives a list of the rocks of the Huronian series 

in order of their abundance and as they occur in stratigraphical succession in the Marquette, Menominee, Penokee, and G-ogebic series. 

Lithologically the rocks are divided 'into (1) Fragmental rocks, exclusive of limestone j (2) Metamorphic rocks, not calcareous; (3) Calcareous 

rocks; (4) Igneous rocks.

The Fragmental rocks include quartz-conglomerates, which occur in 

the middle horizon, both in the Marquette and Menominee and in the 

latter at the base of the series where it holds pebbles of granite, gneiss, 

and quartz. In the Metamorphic rocks not calcareous are included 

many varieties; the mica-bearing series includes granite, syenite, 

gneiss, mica- schists, hornblende-schists, mica-slates, .clay-slates, diorites, 

diabases, quartzites, siliceous schists, chert and jasper rocks, iron ores, 

as well as many others. Among the eruptive rocks is a feldspathic 

series, including granite dikes; hornblendic and pyroxenic series, including diabase and similar rocks, and hydrous magnesian schistose 

rocks which are found in dike-like forms crossiug the quartzites, iron 

ores, and greenstones.

The succession in the Marquette region from the base upward is (a) 

syenite, diorite, diabase, hornblende-schists, slates, conglomeratic 

quartzites, and various quartzose iron ores; (b) quartzite graduating 

into protogine, and containing interstratified beds of dolomitic marble; 

(G) ferruginous quartzose schist; (d) hornblendic rocks with greenstones; (e) ferruginous quartzose flags, clay-slates, and quartzites; (/) 

hornblendic rock? related to diorite and diabase; (</) siliceous hematitic
VANHISE.] LAKE SUPERIOR REGION. 97

and limouitic schistose ores; (/*) diorite, hornblende-schist, and chlorite-schist; (i) arenaceous quartz-schist, banded with micaceous iron 

and quartzose liinonitic ore; '(_;') pure specular hematite and magnetite, 

with banded jaspery schists and interstratified beds of chloritic and 

hydromica-schist; (Jc) an arenaceous quartzite, often semischistose and 

conglomeratic; (1) argillaceous slate;, (m) quartz-schists; (n) anthophy Hi tic schist; (o) mica-schist. Similar successions are given in the 

other regions mentioned and correlated with, that in the Marquette 

region, and all of these successions are compared and correlated with 

Logan's succession in Canada.

The Huronian in the Marquette, Menominee, and Gogebic regions is 

 nonconformable with the Laurentian.

PuMPELLY, 108 in 1878, describes lake Superior as divided into two 

distinct basins by Keweenaw point, the western basin being a geosynclinal trough. The southeastern lip of this trough consists of an immense development of volcanic rocks in the form of great beds and 

flows associated with conglomerates and sandstones, both of which consist essentially of porphyry detritus. This Keweenaw series is more 

nearly conformable with the underlying highly tilted Huronian schists 

than with the Potsdam sandstone. The prominent eruptive rocks of 

the Keweeuaw series fall under the two heads, diabase and melaphyre. 

The changes which have taken place in the interior of the rock masses 

since eruption, that is, the nietasomatic development of these rocks, is 

traced out in great .detail.

WEIGHT,109 in 1879, describes the Laurentian series as consisting of 

coarsely crystalline massive granites, passing into gneissoid rocks, and 

these graduating into mica-schists, and the latter even as imperceptibly 

into slates. The Laurentian granite is regarded as a metamorphic 

sedimentary rock, because the quartz grains contain cavities filled 

with liquid, while igneous granites never contain such cavities, but 

rather those tilled with glass or stone. The lower Huronian. strata have 

been chiefly derived from the ruins of the Laurentian rocks. The nonconformity between the Laurentian and Huronian maybe seen atPcnokee gap. Here the dip of the gneissoid granite is^ibout 70° to the 

souih, while the plainly bedded Huronian strata in direct contact have 

a dip of 05° to the north. At the Macomber mine, near Eegaunee, is 

found a bed of inanganiferons hematitic shale bearing the impression 

of some fossil which Profs. Brush, Verrill, Dana, and Smith pronounce 

to belong to the lower forms of life. The Lower Silurian sandstone 

about the city of Marquette is nearly horizontally bedded, and rests 

imconforinably on and against the Huronian.

liOMTNGrEE., 110 in 1881, gives a general account of the Marquette and 

Menominee iron region, with very voluminous details as to particular 

localities.

The Marqiiettc region. In general remarks on the geology of the Marquette district the succession is (1) Granitic group; (2) Dioritic group; 

Bull. 80 7
98 PRE-CAMBRIAN EOCKS OF NORTH AMERICA. [BULL.8fl.

(3) Quartzite group5 (4) Iron group; (5) Arenaceous Slate group; (6) 

Mica-schist group; and (7) Serpentine group; but later it is seen that 

the Quartzite group reposes upon the Iron group, so that the order 

of 3 and 4 is reversed. The Silurian sandstones rest horizontally on 

the other rock formations and frequently contain fragments of the 

underlying formations. The crystalline granitic masses are directly 

confined to the northern and southern limits of the Marquette district. 

The dip of the strata on the south part of the trough is usually to the 

north, and on the north side to the south, so that we may consider this 

area as a synclinal caused by the upheaval of its northern and southern 

margins. The granitic and sedimentary rock masses are traversed by 

rock belts of a crystalline character, which represent lava streams 

intruded at different periods subsequently to the rocks cut.

In the Granitic group the granites are found interstratified with the 

Huronian schists of the Dioritic group. The granites are usually middling coarse grained and in the main are massive, although distinct 

gneissoid rocks have a limited occurrence. Besides the dioritic dikes 

there are in the granites crystalline non-stratified masses resembling 

eruptive dikes. In several instances granite dikes show a laminar 

arrangement of the mica sc'ales. Also syenites are associated with the 

ordinary granites. The hornblende rocks associated with the granites 

are distinguished from those occupying a higher position in the series 

by the brighter luster of the hornblende crystals. Dioritic rocks occur 

interstratified with the granites, which are probably of the same origin 

as the volcanic eruptives. In the Laurentian rocks no limestones, layers of quartzite, nor beds of iron ore are found. The granitic rocks in 

their present position are actually the younger rocks, as shown by the 

intrusion of large masses of granite between the stratified sediments of 

the Dioritic group.

The dioritic group is regarded as remelted, completely metamorphosed Huronian sediments, their more crystalline character being due 

to their closer proximity to the volcanic forces. The rocks of the Dioritic group include a large succession of schistose beds of uniform 

character, interstratified with massive diorite. In the dioritic rock 

chlorite frequently replaces the hornblende and often seems to be a 

product of its decomposition. The massive diorites are usually conformably bedded with the schists and often insensible gradations from 

the.schistose conditions to the massive diorite can be seen. The exposures of massive diorite generally form a nucleus around which the 

inclosing rock masses are arranged concentrically with a more perfect 

schistose structure. In the Dioritic group are conglomerates. One 

variety is well exposed at Deer lake furnace, where the pebbles are of 

a feldspathic substance which on fresh fracture contrasts little with 

the surrounding schistose mass. Also extensive conglomeratic masses 

are found fall of granite pebbles of large size in Sec. 2,.T. 48 N., R. 26 

W., and in Sec. 29, T. 48 1ST., E. 25 W. In opposition to Brooks it is 

maintained that there is but one iron-group formation.
VANHISB.] LAKE SUPERIOR REGION. 99

The Quartzite group is in places interstratified with ferruginous and 

siliceous seams, as well as novaculitic strata and siliceous limestones. 

Frequently in the quartzite is a conglomerate containing abundant 

quartz fragments, and also not infrequently containing granite and 

slate fragments. Oftentimes these conglomerates containing the granite fragments are very close to the massive granite, while it not infrequently underlies them. At one place in which the quartzite is in contact with the granite the one rock is seen to graduate by imperceptible 

stages into the other, in which case the sedimentary strata are changed 

into the granite-like rock by being exposed to the contact with the 

eruptive granite. In another place a granite breccia containing large 

fragments of granite, is found in connection with such large masses of 

granite as to be too' great to be fragments of a breccia, and this suggests that the nucleus of the hills are solid granites, whose shattered 

portions are recem.en.ted on the spot by sedimentary debris washed 

into the interstices. In the next hill to the south the inclosed waterworn pebbles are in part granite and in part slate. Above the orebearing rock beds is generally a very coarse quartzite conglomerate 

which often has the characters of a coarse grained ferruginous quartzite and grades down into a brecciated ore. The fragments are chiefly 

ore, jasper and quartz, and the cement is arenaceous or ferruginous. 

This occurrence is so general as to suggest that great disturbances not 

of a local extent must have occurred at the end of the era of iron sediments. The number of localities and mines at which this conglomerate 

or breccia occurs is very great. Among the latter are the Home, Gibbon, Jackson, Cleveland, Cascade, Gribben, Salisbury, Lake Superior, 

Champion, Saginaw and Goodrich, Keystone, Eepublic, and Michigamme.

The Iron group occupies a position inferior to the Quartzite group, 

and there are not two horizons here, as supposed by Brooks. It is composed of banded jasper, conformable chlorite-schist, and ore. The oredeposits are not regular sedimentary layers, but the product of the 

decomposition of the impure Jedges by percolating waters, leaching out 

the siliceous matter and replacing it with iron oxide, and are therefore 

very irregular in form. The strata are in a much disturbed condition, 

folded and distorted in every possible way, usually without fault. 

These disturbed beds lie in every instance directly, but often unconformably, on chloritic or hydromicaceous schists, or on crystalline dioritic masses, which are constant associates of the chlorite schists, or on 

clioritic schists. At the Jackson mine are knobs of diorite associated 

Avith schists surrounded by the banded jasper rocks, which are evidently corrugated by the intrusion of this mass. In places the orebearing formation is not found incumbent on the Dioritic group. At 

Teal lake the quartzite is found under the ore and the diorite over the 

ore, which leads to the conclusion that these strata are in an over- 

.tamed position.
100 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [sou.. 88.

The Arenaceous Slate group of great thickness is so designated 

because a large portion of the rocks here included consist of sandy siliceous layers, alternating with slaty argillitic rock beds and occasionally with compact quartzite. The strata in different localities quite 

often differ considerably. The rocks of this group are incumbent on 

the quartzite formation, but also sometimes rest upon the ore-bearing 

rocks, and quite often are found in direct contact with the dioritic 

series. The rocks are sometimes conglomeratic or brecciated, the fragments consisting of different kinds of rocks. In the black roofing 

slates of Huron bay the cleavage is discordant with the bedding. 

Occupying a position above the black slates are the ore deposits of the 

Taylor mine, near L'Anse, and of the Northampton and D'Alaby, north 

of Champion; also the S. C. Smith and other mines. These ores are 

contemporaneous and equivalent to that of the Commonwealth in the 

Menominee district.

The Mica-schist group is found exposed for the most part about 

Michigamme village. The Serpentine group includes the rocks of 

Presque isle and those of similar class. The Silurian sandrock reposes 

unconformably upon the Serpentine formation at Presque isle. Besides 

the serpentine and other magnesian silicates, limestone comprises an 

important share of this group.

The seven previous groups, considered to be a succession of sedimentary strata, are intersected by various dikes, among which are a 

dioritic rock and dolerite dikes, the latter of which are later in age than 

the former. No proof has been found of any discordance between the 

granites of Marquette and the adjoining Huronian beds. On the contrary, outcrops of the two kinds of rocks exhibit a remarkable parallelism in strike and dip, and in many localities the Huronian schists and 

belts of granite are interlaminated in perfect conformity. The granite 

is, however, regarded as intrusive masses. The granites are therefore, 

with reference to the stratified sedimentary rocks, actually the younger 

rock..

The Menominee region. Many localities and sections in the Menominee iron region are described in detail. The Silurian sandstone is found 

to rest unconformably upon the nearly vertical Huronian strata. Near 

Sturgeon river falls, in the river, the quartzite formation reposes unconforniably on the granite. Thick layers of limestone are found in 

the series, and this is sometimes conglomeratic. The fissile phyllite 

schists are found in discordance with the dioritic schists at lake Hanbury. The granitic and giieissic rocks south and north of the Felch 

mountain ore formation are found to be absolutely identical. The dioritic rocks are found generally and play the part of an intrusive with 

regard to the strictly sedimentary rock beds of the Huronian series. 

The dioritic group is held to be older than the iron-bearing group because it exhibits a greater degree of metamorphism and on the ground 

that it is lithologically like the equivalent dioritic group of the Mar-
VANHISE.] LAKE SUPERIOE REGION. 101

quette district. It has evidently been transformed under the cooperation of heat and partially brought into a plastic condition.

In the eastern part of the Menominee region the rocks found comprise, in descending order, the lake Hanbury slate group, perhaps 2,000 

feet in thickness; the Quiunesec ore formation, which comprises micaceous and argillitic strata, containing ore bodies, not less than 1,000 feet 

thick; and the Norway limestone belt, at least 1,000 feet thick. The 

Commonwealth mine, in the western part of the Menominee district, represents a higher horizon than the Quinnesec ore formation.

WiaiCHELL (N. H.), 111 in 1888, describes in the Marquette district the 

conglomerate overlying the ore and jasper formation at several mines, 

and places the overlying quartzite in the Potsdam. North of Bessemer 

is a basal conglomerate of the Cupriferous series which is inferred to lie 

nnconformably upon the Gtogebic iron-bearing rock. This conglomerate 

appears to be the equivalent of the overlying Potsdam conglomerate of 

the Marquette region, which makes the Gogebic series pre-Potsdam. 

The granite underlying the Huronian slates at the Aurora mine was 

originally a conglomerate, bnt it has acted the role of an eruptive rock 

and has flowed over the adjoining sedimentary strata. This granitic 

conglomerate is parallelized with the Ogishki conglomerate of Minnesota, and the overlying sedimentary rocks are the equivalent of the 

Animikie.

WINCHELL (ALEX.),112 in 1888, finds the Marquette iron-bearing rocks 

to have the same geological position with respect to the crystalline 

schists and gneisses and to consist of sediments of the same character 

as those of the Vermilion range. At Deer lake furnace is a peculiar 

conglomeratic rock which appears sedimentary, but is much altered and 

has a quasi-eruptive aspect. This conglomerate is like that of Stuntz 

island in Vermilion lake. Near Negaunee is an argillite which has a 

lower dip than a greenish chloritic quartzose rock across a railroad from 

it, and the two are therefore unconformable.

The rocks of Marquette are older than the Huronian because they 

differ from them lithologically; because the Canadian Huronian is immediately succeeded by the Paleozoic system, while the Marquette strata 

is not; because some evidences are found that in the Marquette district there is an overlying unconformable sub-Paleozoic system; and 

because the Marquette series, being the equivalent of the Vermilion, is 

older than the Animikie slates, which are the equivalent of the Huronian.

The rocks of the Gogebic range are regarded as the equivalent of 

those of the Marquette region because they resemble them lithologically, and because they are in an analogous position to the crystalline 

rocks. Between the Penokee series and the underlying schists there is 

a marked unconformity, the Penokee rocks dipping to the north, while 

the hornblende-schists dip to the south. The Penokee series strata are 

lithologically unlike the ore-bearing strata of Gogebic, Marquette, and
102 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. -[BULL. 86.

Vermilion regions, but resemble those of the Animikie series and are 

therefore perhaps Huronian, while the Gogebic iron-bearing strata are 

not.

WADSWORTH,113 in 1890, gives a general account of the geology of 

the Marquette and Ke ween aw districts based upon his own and other 

works. The Azoic system includes fragmental and eruptive rocks. 

Among the former are various argillites and schists of the Marquette 

district. Among the eruptive rocks are placed the jaspilites and their 

associated ores, with the exception of certain soft iron ores of chemical 

origin. The Keweenawan is again placed as a part of the Potsdam, 

since the first lava flow found on Keweenaw point flowed over the 

Eastern sandstone. Subsequently there has been a fault line or fissure 

running near the contact of the sandstones and lavas. This fault is 

regarded as normal and it accounts for the fact that sometimes the 

lavas and sometimes the associated conglomerates are brought in contact with the Eastern sandstone along the fault line.

WADSWORTH, 114 in 1891, modifies somewhat the foregoing account of 

the Azoic system. A portion of the jaspilites and associated iron ores 

are still held to be eruptive, but it is suggested that even for these 

supposed nonfragmental jaspilites of Ishpemiiig and Negaunee, their 

present relations may be due to sedimentary and chemical action and 

the squeezing together of the jaspilite and schist. The jaspilite and 

ore, with the associated quartzites, occurring at Cascade, Eepublic, 

Humboldt, and a part of those at Ishpeming and Negaunee, as well as 

those of the overlying quartzites and schists, are sedimentary. In the 

Marquette district there are three distinct geological formations or ages 

in ascending order as follows: First, the hornblende-schist and granite 

of Cascade or Palmer and the nonfragmental jaspilite and ore of Ish> 

perning and Negaunee the Cascade formation. Second, the fragmental jaspilite and ore, with their associated quartzites and schists of 

Cascade, Eepublic, Humboldt, Ishpeming, IsTegaunee, and elsewhere 

the Eepublic formation. Third, the overlying conglomerates, quartzites, and schists of Cascade, Eepublic, Holyoke, and elsewhere the 

Holyoke formation.

Above the detrital Eepublic formation at the Cascade range is another 

detrital'formation which contains water-worn debris derived from the 

underlying deposits of jaspilite and ore, and is therefore unconiformably above it. At present it is not possible to determine positively 

whether there are really three formations as given, or from four to six 

different ones, or whether the three may be reduced to two.

WADSWORTH, 115 in 1891, finds that the Lower Silurian, containing 

Trenton fossils near L'Anse, overlies the sandstone conformably, both 

having a synclinal structure; which tends to confirm the commonly 

received view of the Potsdam age of the Eastern sandstone.

WADSWORTH,116 in 1891, gives observations upon the South Trap 

range and adjacent sandstones. Various places are mentioned, includ-
LAKE SUPERIOR REGION. 103

ing Silver mountain, which are composed of lava flows. These traps 

sometimes have a dip not higher than. 9° to 20°. In Sees. 11,13 and 

14, T. 46 K, E. 31 W., sandstone is founi overlying the lava flows. The 

Eastern sandstone on Traverse island, in Keweenaw bay, is said to 

have an inclination of from 5° to 14°, while in the vicinity of Torch lake 

it has a dip of from 5° to 23°. It is concluded that the above observations go to show that the lava flows of the South Trap range east of 

lake Gogebic do not dip at a high angle, as has been generally asserted, 

and further that the Eastern sandstone is not horizontal, as has been 

generally stated, but that the two dip at a low angle, generally 5° to 

20°. These observations also indicate that the Eastern sandstone and 

the lava flows of the South Trap range are one formation, and are as 

conformable as eruptions of lava can be with a contemporaneous 

sedimentary deposit.

EoMiNG-ER,117 in unpublished manuscript of the Michigan Survey for 

1881 to 1884, farther reports upon the complex described in the former 

volume as the Huronian system. The lower granite and gneissoid portion of the rock groups in the Marquette region exhibits the characters 

of an eruptive and not of an altered sedimentary rock. Generally a 

solid crust of granite probably served as a substratum on which the 

Huronian sediments were laid down, but an opportunity is not often 

afforded to see the rocks in contiguity well enough exposed to allow a 

discrimination as to whether such contact is an original primary one or 

resulted from, dislocation. The existence of granite as a surface rock at 

the time the Huronian sediments formed is proved by the occurrence of 

belts of granite, conglomerate and breccia in different horizons of the 

series.

A large belt of con glomerate formed of rounded weather-worn granite 

pebbles and schistose rock fragments, cemented by a matrix of similar 

schistose material, is seen in contact with a granite belt in the south 

half of Sec. 2, T. 48 K, E. 26 W. j in the SE. £ Sec. 22, T. 47 N., E. 26 W. j 

and in the north half of Sec. 29, T. 48 E"., E. 25 "W. In the first of these 

localities the fragments are different from the underlying granite. The 

second locality furnishes a better proof of the deposition of Huronian 

sediments on a base of granite. Here several knobs centrally composed of massive granite are surrounded by a mantle of coarse granite 

breccia, with a well laminated quartzose material as a cement. This 

breccia is conformably succeeded by hydromica-slates, rnterlarninated 

with heavy belts of compact quartzite. At the third locality granite 

conglomerate is interlaminated with dioritic schists, but is remote from 

granite outcrops. The gradation of the quartzite formation into the 

granite, described in the previous report as occurring in the north part 

of T. 47 N., E. 25 W., is now considered as a recemented mixture of 

granite fragments mingled with arenaceous material, although it is singular that the orthoclase crystals copiously found in the mass have all 

sharp outlines and are quite fresh.
104 PEE-CAMBEIAN EOCKS OF NOETH AMEEICA. [BULL. 86.

The upheaval of the granite and its intrusion into the overlying strata 

occurred in all probability near the termination of the Huronian period, 

as we find the granite in contact with all the Huroni an strata up to the 

youngest, and these always in a dislocated position. Intrusive belts of 

granite are usually never found to intersect beds higher than the ironbearing group, except in the country north of the Penokee range in 

Wisconsin, and in the vicinity of Duluth, Minnesota, where granite or 

granite-like rocks cut across eruptive belts of gabbro which are themselves more recent than any of the sedimentary strata of the Hurouian. 

These granites differ from the ordinary granites at the base of the 

Huronian, and are most likely younger. The dislocation of theIluronian 

beds is not exclusively due to the upheaval and intrusion of the granite, 

but has been caused in part by diorite and diabase intrusives which 

intersect the granite as well as the incumbent beds. The diorites intersecting the granite are identical with similar rocks interstratified with 

the schists of the Huronian group conformably or transversely intersecting them, and they therefore represent one and the same volcanic 

injection. From the massive forms of diorite a gradation exists into a 

schistose condition. This led to the conclusion in the former report 

that the massive diorites had suffered secondary fusion; but as the 

author is now convinced that schistose structure is not necessarily the 

result of aqueous sedimentation, it is concluded that the dioritic group 

does not belong in the sedimentary succession. Dolerite or diabase 

rocks intersect in dike-like-form all the Huronian rocks, as well as the 

granites. As they are like those of the copper-bearing series, these 

rocks, as well as the contemporaneous flows, are regarded as belonging 

to the same geological period. In the Felch mountain region one dike 

(1.5 or 16 feet in thickness) of holocrystalliue granite cuts across the ironbearing series. In Sec. 33, T. 42 IS., E. 28 W., another granite dike cuts 

through the iron-bearing rocks.

Above the iron-ore group of the Marquette and Menomin.ee districts 

before described is found at many localities important deposits of iron 

in both these regions which belong in the Arenaceous Slate group. 

There are, therefore, two iron horizons instead of one, as before supposed. The mica-schist formation, supposed to belong above the Arenaceous Slate group, is found to dip conformably below it in some places, 

and therefore is really a part of the Arenaceous Slate group, and is 

believed to represent its middle horizon. The slate group about L'Anse 

and Huron bay is black and often graphitic. The slate beds at Plumbago creek are succeeded by schistose beds richer in red feldspar and 

containing little quartz, which might by superficial examination be mistaken for granite, but which fs evidently a fragmental rock formed by 

the detritus of the granite which near by forms large mountain masses, 

and the granite of which is very rich in red feldspar and contains comparatively little quartz.'
VAN man.] LAKE SUPERIOR REGION. 105

The Gogebic region is described and the rocks are divided into granitic, dioritic, iron ore, and upper slate groups, which are analogous to 

th e similar groups in the Marquette country. Granite seam s were found 

here cutting across the dioritic schists, but were not found to cut the 

truly sedimentary strata. Locally, in contiguity with the granite, are 

heavy quartzite strata w'hich are often conglomeratic, and are filled with 

rounded granite pebbles. The dioritic rocks above the granite often 

have a brecciated or conglomeratic structure, the fragments being various kinds of diorite cemented by the same material. The diorite is of 

eruptive character, as is shown by the occurrence of belts of it cutting 

transversely through the ore-bearing series. Limestones are also found, 

which occupy the same position as the limestones below the ore-bearing 

strata in the Menominee district.

The succession in the Felch mountain, from the base upward, is (1) 

granitic or dioritic rocks; (2) quartzite beds; (3) fissile quartz schists; 

(4) micaceous argillite; (5) crystalline limestone with siliceous seams; 

(6) ferruginous quartzites, containing the ore beds.

SECTION IV. WOEJC OP THE WISCONSIN GEOLOGISTS AND ASSOCIATES.

PERCiVAL, 118 in 1856, describes the quartzite ridges of Baraboo and 

Portland. The rock is a hard granular quartz, which has more or less 

distinct lines of stratification, and resembles much a Primary granular 

quartz. In the Baraboo rock are layers more or less filled with rounded 

pebbles of quartz, resembling layers of the same kind in the lower 

sandstone, and oblique cross lines between the regular lines of stratification, which occurrences appear to connect it with the lower sandstone. The dip of these ranges is at a moderate angle to the north, 

and if the rock is formed from the sandstone by igneous action from 

beneath, the inetamorphic change has not been- accompanied by much 

disturbance of the strata. The localities in which Primary rocks are 

found are all within the limits of the lower sandstone, and most of them 

occur at the falls of the northern rivers. These rocks are mainly hornblendic and syenitic, although trap rocks resembling the intrusive traps 

of Connecticutareseen,butthese arebelieved to berather Primary greenstones. Descriptions are given of the rocks of Marquette and Waushara counties, of those of Black, Wisconsin, St. Oroix and other rivers. 

On Black river the rocks are syenite, greenstone and chlorite slate, the 

latter accompanied by iron ores.

DANiELj 119 in 1858, describes the iron ores of Black river falls as associated with the chloritic and micaceous slates of the Azoic system. 

Syenite is also found adjacent. The fossiliferous horizontal sandstone 

rests upon the upturned edges of the Azoic slates, and at the base of 

it is a brecciated conglomerate consisting of sand, ore and slate. In 

the lower part of the Baraboo valley are lofty ranges of hard quartzite 

which are the soft crumbling Potsdam sandstone violently disturbed 

and changed.
106 PBE-CAMBEIAN ROCKS OF NOETH AMEEICA.

LAPHAM, 120 in 1860, describes the Penokee iron range. Here is found 

a mountain mass of iron ore in an ancient chloritic slate, which rests 

upon a light colored quartz rock. Above and north of the ore the slate 

is hardened, probably by some volcanic agency. The whole series dip 

to the north.

HALL ( JAMES),m in. 1861, describes the quartzite ranges of northern 

Wisconsin, and particularly those of Spirit lake, as having been original 

stratified sandstones which have undergone subsequent metamorphism. 

These rocks are folded with their axes lying in an east and west direction and had become uplifted and metamorphosed before the commencement of the Potsdam era. In the quartzites in two or three localities 

are found beds of conglomerates. These metamorphic masses are in all 

probability the extension of the Huronian formation of Canada.

HALL (JAMES), 122 in 1862, describes the central and northern areas of 

Wiscon sin as consisting of the Azoic rocks. These are hard and crystalline, are often destitute of lines of bedding, though they are in reality 

as regularly stratified as the more modern formations. Notwithstanding their crystalline character, their alternation of beds of different 

texture indicates their original different mechanical conditions as clearly 

as in any of the unaltered strata. They were deposited precisely as 

clay, sand, and limestone strata of more recent geological periods, and 

owe their present character to metamorphism. These rocks are granitic, syenitic, gneissoid, or hornblendic. In the southern part of the 

area of the crystalline rocks are numerous elevations of them appearing within the limits of the succeeding stratified rocks, so that we know 

that these latter are of later date. North of the Azoic rocks is the 

range of trap, conglomerate and sandstone bordering Lake Superior 

and known as the copper region. The quartzite ranges of Baraboo and 

Necedah hold the same position relative to the Potsdam sandstone as 

the Huronian system of the Canadian survey.

WniTTLESEY, 123 in 1863, describes the copper-bearing strata of Keweenaw point as extending southward across the boundary of the 

state of Michigan into Wisconsin, a distance of 160 miles. The order 

of rocks along the line is everywhere the same. Beyond the copper 

range, which is nearer to lake Superior, is a second range known as 

the iron range, and to this the name Pewabik was applied, although by 

a misprint it was transformed to Penokee.

Passing from lake Superior to south of the iron range, the structure in 

descending order is as follows: Formation No. 1, Potsdam sandstone, 

consisting of sandstones, conglomerates, black slates, and alternations 

of trap and sandstone; No. 2, Trappose, in two members; No. 3, Hornblendic; No. 4, Quartz, with slaty layers, separated into two members 

by a bed of magnetic iron and iron slate; No. 5, Granites and syenites 

of central Wisconsin. This system is everywhere stratified and conformable throughout. On the Bad and Montreal rivers are found no 

masses of crystalline limestone.
VAN RISK.] LAKE SUPERIOR REGION. 107

TRYING, 124 in 1872, maintains that the quartzites of Sank connty are 

unconformably below the Potsdam, because they are uptilted at a 

high angle, while the Potsdam is horizontal, and the horizontal sandstorie abuts against the quartzite and holds fragments derived from 

it. These quartzites are either Laurentian or Huronian.

MuBRiSH,125 in 1873, describes the quartzite ranges of Baraboo as a 

metamorphic sandstone of the Potsdam age. On the Black and Yellow rivers are found granitic andhornblendic Azoic and plutonic rocks. 

At Black river falls are knobs of magnetic ore in a series of elongated 

knobs or mounds, associated with quartz and micaceous slate. At 

Grand rapids, on the Wisconsin river. Azoic rocks similar to those onBlack river are found. A quartzite mound at Necedah occupies a 

geological position similar to the iron ores at Black river falls.

EATON/26 in 1873, maps the quartzites of the Baraboo river. -At 

Ableman's the highly tilted quartzites are flanked on both sides by 

horizontal sandstone and conglomerate, the latter having angular fragments of the quartzite of varying magnitudes. The overlying sandstone is exactly like that described by Irving at Devil's lake as containing Potsdam fossils. The sandstone is above horizontal limestone 

containing Pleurotomariai! The quartzite is then an old Azoic reef of 

tilted rocks which has suffered, enormous erosion before washed by the 

waves of the Potsdam sea.

IRVING,127 in 1873, maintains the pre-Potsdam age of the Portland 

quartzite on the same ground as the pre-Potsdam age of the Baraboo 

ranges. There is a close similarity between the Baraboo and Portland 

quartzites and the rocks in northern Wisconsin and Michigan which 

are now regarded as Huronian.

InviNG,128 in 1874, describes as occurring in northern Wisconsin four 

distinct groups of rocks, the Laurentian, Huronian, Copper-bearing, 

and Lower Silurian. The Laurentian consists of granites, gneisses, 

and syenites for the most part, although there may be various schist 

beds present. The Huronian rocks consist of siliceous schists, quartz 

rock, and black slates, magnetic and specular schists and slates, 

metamorphic diorite and diorite-schists. Its lowest portion is of 

simple siliceous schist with some granular white quartz, gray quartzite, and black slate. The central portion consists of magnetic and 

specular slates and schists in which all the ores are found, and the 

highest and northernmost portion consists of diorites, diorite-slates, 

diorite-schists, and quartz-slates. The Copper-bearing series is next 

north of and immediately overlies the Huronian, and is of enormous 

thickness, never less than 4 miles. The lower portions of the group 

are probably in part of igneous origin, but the upper portions are beyond all doubt exclusively the results of sedimentation. The group 

consists of shales, sandstones, conglomerates, amygdaloids, and traps. 

The sedimentary series do not altogether overlie the trappean beds, 

but are near their junction directly and unmistakably iuterstratified
108 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

with them. The Silurian rocks in Ashland county are in. a horizontal 

position in a trough between two lines of highly tilted beds of the 

Copper-bearing series. At one place the horizontal sandstone is found 

within a feAv hundred feet of the copper-bearing trap and within 2 miles 

of vertical sandstones of the same group.

In Douglas county the horizontal sandstone is traceable to within a 

short distance of the trap, and sometimes to actual contact, the trap 

dipping, whenever it is observable, always to the southward, and 

having no tilted sandstones and conglomerates associated with them. 

As the Huronian and Copper-bearing series are in apparent conformity it is concluded that they were once spread out horizontally 

one over the other, and owe their present highly tilted position to one 

and the same disturbance; and subsequently, after a long period of 

erosion, the horizontal Silurian sandstones were laid down over and 

against the upturned edges of the Copper-bearing series; and that 

hence the Copper-bearing series is more nearly allied to the Archean 

than to the Silurian rocks. One fact is, however, difficult of explanation on this hypothesis. In Douglas county at several places the horizontal sandstones, when traced to their junction with the southward 

dipping trap, present ^remarkable change; the horizontal layers are 

suddenly seen to change from, their ordinary position, to a confused 

mass of broken layers, dipping in every conceivable direction and increasing in confusion as the trap is approached, until finally the whole 

changes to a confused breccia of mingled trap and sandstone fragments. 

It is suggested that this appearance is due to the movement of the solid 

trap northward against the sandstone since the deposition of the latter 

rock. The great lake Superior synclinal of Copper-bearing rocks is 

found to extend west into northern AYisconsin.

SWEET, 129 in 1876, describes the junction of the Laurentian and Huronian rocks on Bad river. Here'at the base of the Huronian series is 

a siliceous marble dipping to the northward at an angle of 66°, while 

100 feet to the south is a ledge of gneissoid granite showing a well 

denned dip of 77° to the south. There can be no doubt of the unconformability of these formations. The Penokee series is found to be 

aboii* 5,000 feet thick, to be everywhere conformable, and to dip about 

C6° to the north.

On the Chippewa is found a quartzite which has a layer the lowest 

stratum of which is a reddish metaniorphic conglomerate having a 

thickness of 300 feet. The pebbles of this conglomerate are either 

jasper or amorphous quartz. The conglomerate and quartzite are distinctly and heavily bedded. South of this quartzite axe syenitic granites which are assumed to be of Laurentian age, and the quartzites 

and conglomerates are assumed to overlie them unconformably. A 

short distance north of the mouth of Snake river cupriferous melaphyres 

and amygdaloids are overlain by horizontal beds of light colored Potsdam sandstone, while a few miles to the north conglomerates and shales
VANHISE.I LAKE SUPERIOR REGION. r 109

conformably overlie the cupriferous strata. -The conglomerate is heavily bedded, but does not cover the melaphyres and amygdaloids at all 

points, appearing to fill pockets and depressions in them rather than 

being interstratified. At St. Oroix falls on the St. Croix river Potsdam sandstone containing fossils are found in a horizoatal position within 

a few feet of the cupriferous rocks. Depressions and pockets in the surface of the cupriferous rocks are filled with horizontal layers of the 

sandstone, and detritus from the crystalline rocks are found in its layers. The lake Superior synclinal is traced westward across the state 

of Wisconsin and enters the state of Minnesota. It is then over 300 

miles in length and from 30 to 50 miles in width.

IftViNG, 130 in 1877, summarizes the facts proved as to the older rock 

series of Wisconsin. There are here four series: The oldest (1) are 

gneisses and granites with other rocks; these are overlain unconformably by (2) a series of quartzites, schists, diorites, etc., with some 

gneiss and granite; these in turn are overlain probably also unconformably, but this is not certainly proved by (3) the Copper series, 

which includes greenstones and melaphyres and also great thicknesses 

of interstratified sandstone, melaphyres, amygdaloids, and shales, the 

whole having a thickness of several miles; these finally are unconformably covered by (4) a series of unaltered horizontal sandstone including 

numerous fossils, many of which are closely allied to those of the Potsdam sandstone of New York, and all of which have a marked Primordial aspect. To the Laureutian and Huronian systems of Canada are 

referred (1) and (2) because they bear the same relations to one another 

and to the Copper series that these systems do.

The exact junction between the Potsdam sandstone and the Hnronian quartzite is seen at numerous places. The Potsdam, containing 

fossils and numerous fragments from the older rocks, lies upon and 

wedged in between the tilted ledges of the Huronian. Exactly similar 

unconformability is to be seen at the Dalles of the St. Croix between 

the Potsdam and Copper series.

WiCrHT, 131 in 1877, describes the horizontal Potsdam sandstone as 

resting on the uneven and tilted surface of the underlying igneous or 

crystalline rocks at St. Croix falls. Almost in contact with the trap 

the sandstone contains numerous well preserved fossils. At I hue 

island in Kettle river the Superior red sandstone contains abundant 

fragments of the adjacent trap, forming abrecciated conglomerate kindred to the conglomerate which-extends from Keweenaw point along 

the northern base of the Porcupine and Penokee mountains. Everywhere this conglomerate is composed of fragments of the more elevated 

Huronian or trap ridges. The Superior red sandstone, wherever it 

borders the trap ridges, shows that it has been tilted, broken up, or 

crushed. It appears that the trap, whether erupted or upheaved convulsively or slowly, encountered this formation in its ascent. On the 

contrary, the Potsdam sandstone everywhere rests in a horizontal
110 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BOLL. 86.

undisturbed position on the bedding of the trap. Either the Superior 

red sandstone is older than the Potsdam or the trap rocks in conjunction with the Superior red sandstone are younger than those in conjunction with the Potsdam.

CHAMBERLIN, 132 in 1877, describes the Archean rocks which in the 

eastern part of Wisconsin protrude bat are not intrusive in the Paleozoic formations. These are the Mukwa granite, the Berlin porphyry, 

the Pine bluff quartz-porphry, the Marquette quartz-porphyry and the 

quartzites of Portland and Waterloo. The porphyries are found to 

have obscure but distinct bedding. The metamorphosed quartzites 

show ripple marks and contain conglomeratic layers. The Potsdam 

sandstone and Lower Magnesian limestone rest in a horizontal position 

against and contain fragments from the crystalline rocks. The quartzites are regarded as originally sandstones and conglomerates which 

were metamorphosed before the deposit of the neighboring horizontal 

rocks, and which have been tilted and eroded before the stratified rocks 

were deposited. These quartzites are regarded as a portion of the Baraboo quartzite series.

IRVING-, 133 in 1877, describes the Archeau rocks which cover all of 

Marathon, most of Wood, and much of Clark, Jackson and Portage 

counties, in Wisconsin. The Laurentian is a great mass of crystalline 

rocks, granite, gneiss, chloritic,micaceous and hornblendic schists which 

are folded and eroded so as to offer the greatest obstacles to their detailed study. On the south side of the Laurentian core, on Black river, 

and in isolated masses, are ferruginous schists, quartzites, and quartzporphyries, which are probably Huronian. The presence of these rocks 

on the south, the quartzites of Chippewa and Barron counties on the 

west, and the Huronian rocks of the Penokee range on the north leads 

to the Suggestion that the Huronian rocks entirely surround the Laurentian core of northern Wisconsin. The line of junction between the 

Archean area and the Potsdam formation to the south is exceedingly 

irregular. The latter always rests in a horizontal position upon the 

crystalline formations with the most marked unconformability, the exact contacts being found at several places. The most abundant of the 

crystalline rocks is gneiss, and the original bedded condition of the 

whole series is evident, not only by a prevailing gneissoid and schistose 

character, but also by the existence of distinct bedding planes which 

can generally, even in the granitoid kinds of rocks, be readily made out. 

The processes of metamorphism and disturbance have been carried to 

the last extreme, as shown by the highly crystalline character of the 

rocks and the fact that the gneiss grades into granite, as well as by 

the greatly contorted condition of the gneiss lamina and the close folding of the whole series. While the series as a whole is bedded, distinctly intrusive granite occurs, as shown by the way in which it joins 

and penetrates the bedded rocks. The main area of the crystalline 

rocks certainly belongs to the Laurentian, and a small area only on the 

south of the district is doubtfully Huronian.
VANHISE.] LAKE SUPERIOR REGION. Ill

Very numerous details are given as to particular localities, 

the manner of occurrence and relations of the different varieties of 

rocks and the unconformities which exist between them and the Silurian. On Mosinee and Eib hills are found large exposures of quartzite, 

At Black river falls the regularly bedded succession of highly tilted 

strata of many members consists in large part of regularly laminated 

schistose rocks, such as ferruginous quartz-schist and magnesian schist 

or slate, having together an approximate thickness of at least 5,000 

feet. Gneiss and granite are also here found.

Isolated from the main Archean area are quite numerous exposures 

of crystalline rocks which protrude in mound-like forms from beneath 

the horizontal strata. The largest of these are the quartzite ranges of 

Baraboo. About many of these areas are found horizontal sandstone 

lying immediately against the tilted crystalline rocks and carrying pebbles and bowlders derived from them, proving that they are all of 

greater antiquity than the surrounding sandstone layers. These relations are particularly well shown in the Baraboo quartzite ranges. Aside 

from these ranges, the more important areas are theMarcellou, Observatory hill, Moundville, Seneca (Pine bluff), Marquette and Berlin 

quartz-porphyries, the Montello and Marion granites, and the Necedah 

quartzite.

InviNGr,134 in 1878, describes at Potato, river the siliceous slate, one 

of the lower members of the Huronian, as in contact with the chloritic 

gneiss of the Laurentian. The slate inclines at a high angle to the 

north, while the gneiss layers dip to the south and strike in a direction 

oblique to that of the slate layers.

CHAMBEKLiN, 135 in 1878, describes on the Gogogashugun, in the 

Penokee district, the exact junction between the Laurentian and Huronian series. The Laurentian member consists of a peculiar gneissoid 

rock like that which occupies a similar relation at Penokee gap. The 

Huronian lies in absolute contact with this. Its siliceous material at 

the time of its deposition so insinuated itself into the irregularities of 

the surfaces of the gneiss that the two formations are interlocked, and 

a hand specimen was obtained, one portion of which is Laurentian 

gneiss and the other Huronian schist, the two being unconformable. 

The Huronian siliceous schists are overlain by beds of white and red 

quartzite, and these graduate into alternating layers of quartzite and 

iron ore. The iron ore horizon is here hematitic and soft, but is the 

equivalent of the hard magnetic horizon to the west. In this part of 

the belt is presented the greatest probabilities of the existence of workable ore.

IRVING,136 in 1880, gives a comprehensive account of the general 

structure of northern Wisconsin. Here are found four great systems, 

the Laurentian, Huronian, Keweenawan, and Lower Silurian, all of 

which are unconformable with each other. The rocks of the crystalline nucleus are correlated with the Laurentian of Canada because they 

sustain the same structural relations to the Huronian, Keweenawan,
112 . PRE-CAMBRTAN ROCKS OF NORTH AMERICA. [BULL. 86,

and Lower Silurian as does the typical Laurentian of Canada, and because they have the same general lithological peculiarities. There can 

be no reasonable doubt that they are directly continuous with the 

Canada Laurentian. The prevailing rocks are granite and gneiss. 

These rocks are greatly folded and have certainly an enormous thickness. It is evident that these rocks are of true sedimentary origin.

The granites are generally without distinct bedding, but no eruptive 

granite recognizable as such has been observed.

Lying immediately against the Laurentian, and sharply denned from 

it, extending from Montreal river to lakeNumakagon, is a belt of schistose rocks which are beyond question the westward extension of the 

iron-bearing series of the upper peninsula of Michigan. This belt has 

an aggregate thickness of strata of 13,000 feet. The subdivisions, beginning below, are (1) crystalline limestone 5 (2) quartz-schist and argillitic mica-schist; (3) tremolitic magnetite-schists, magnetic and specular 

quartzites, lean magnetic and specular ores; (4) alternations of black 

mica-slate with diorite and schistose quartzites; (5) mica-schists with 

coarse intrusive granite. These major divisions" are again subdivided 

at Penokee gap and vicinity. The system always dips north, usually 

at a high angle, the strikes are oblique to the underlying Laurentian 

gneiss, proving the unconformability of the tAvo systems, the actual 

contact of which can be seen in several places. These rocks are regarded as the equivalent of the Huronian of Canada, because they are 

the direct continuation of the iron-bearing system of Marquette, because 

the grand divisions of the Bad river and Marquette system are similar, because they show the same relations to the Laurentian and Kcweenawan systems as found in the Huronian of Canada, i.-e., newer 

than the former and older than the latter, and because the Marqnette 

and Menoininee sediments are in unconformable contact with the Lower 

Silurian sandstone.

The Keweenawan system is a distinctly stratified one, in large measure made up of eruptive rocks in the form of flows. These constitute 

the lower 10,000 feet of the system, and above these' are found the detrital rocks, increasing in frequency, until they wholly exclude the igneous rocks in the upper 15,000 feet. The eruptives of the system are 

chiefly diabase, melaphyre, and gabbro. The succession on the Montreal river is (1) chiefly diabase and diabase amygdaloid, with little 

satisfactory appearance of bedding and having a width of about 33,000 

feet; (2) alternations of (1) with red sandstone and shale, 1,200 feet; (3) 

bowlder conglomerate, 1,200 feet; (4) alternations of shale and quartzless sandstone, 350 feet; (5) red sandstone and shale, 12,000 feet. If 

the series is regarded as a continuous one it is at least 50,000 feet thick. 

There are two prominent belts of the Keweenaw rocks in northern Wisconsin lying parallel to each other and having between them a synclinal 

depression which is occupied by Chequamegon bay. The Keweenawan 

system is evidently newer than the Penokee system. That the two sys.*
VANHISB.] LAKE SUPERIOE KEGION. . 113

terns are actually nonconformable in these regions is not evident, for 

in sections the dip in passing from one to the other is generally nearly 

the same. That there is a real unconformity is indicated by the facts 

(1) that in passing westward irom Penokee gap the uppermost beds of 

the Huronian are gradually cut off by the gabbro that forms the base 

of the Keweenaw series; (2) that there is not an absolute conformity in 

dip between the Huronian and Keweenawan rocks; (3) west of lake 

Numakagon the diabases and other eruptive rocks of the Keweenaw 

series appear completely to cover the Huronian.

The lake Superior sandstone is always in a horizontal position and is 

more highly siliceous than the sandstones of the Keweenawan system. 

At the St. Louis river it overlies unconformably the Huronian schists. 

In Douglas county are several junctions of the sandstone with the Keweenawan rocks. Here the horizontal sandstones in approaching the 

eruptive rocks of the Keweenawan system are found to be brecciated 

and tilted, the original lines of deposition being sometimes entirely 

obliterated. These peculiar appearances are regarded as due in part to 

the naturally confused mode of deposition on the cliffy shore in which 

the sandstone was originally deposited; but a slight movement of the 

deep-seated crystalline rocks against the more superficial sandstones 

woujd also account for much of the phenomena. That the sandstone 

formation rests unconformably upon th Keweenawan system is further 

shown by the fact that in the Dalles of the St. Croix the horizontal 

sandstone and shales, with characteristic Primordial fossils, lie upon 

the irregular and eroded surface of a Keweenawan melaphyre.

The Penokee series is compared with the Marquette Huronian and 

there is found to be a general likeness in the rock succession in the two 

regions. Very numerous detailed sections and outcrops at particular 

localities are fully described and mapped.

WEIGHT,137 in 1880, describes the Hurouiau series west of Penokee 

gap. The succession here found is limestone, chloro-silicious schists, 

quartzites, magnetic schists, Keweenawan; the magnetic schists being 

occasionally interstratilied with greenstone. At Penokee ga,p is found 

adolomitic limestone overlain with quartzite and chloro-siliceous schists, 

which rest unconformably upon the Laurentian rocks. The Huronian 

rocks here have a dip of 66° to the north, while the Laurentian rocks 

have a southern inclination from 65° to 80°. West of Nuinakagon lake 

the magnetic attractions are found to cease and the Copper-bearing 

series and granite belonging to the Laurentian are found in direct contact. This appearance is regarded as being due to the covering up of 

the Lower Huronian by the Copper-bearing rocks.

SWEET,138 in 1880, describes the geology of the western lake Superior 

district. The geological formations here found comprise the Laureutian, 

Huronian, and Keweenawan systems. The Keweenawan rocks are found 

in a great synclinal. In ndrthern Wisconsin, below the Keweenawan, 

no southward' dipping rocks are found referred to the Huronian, but in 

Bull. 86 8
114 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

Minnesota, along the St. Louis river are strata which occupy a position 

inferior to the Keweenawan series, are lithologically like the slates of 

Ashland county, and are cut by numerous dikes in lithological character precisely like the rock at the base ot the Copper-bearing series. 

They are hence regarded as Huronian. The Copper-bearing strata consist of a detrital upper portion of sandstones, conglomerates, and breccias, 

having a maximum thickness of 9,000 feet, and of eruptive strata, consisting of melaphyre, diabase, porphyry, gabbro, etc., having an apparent maximum thickness of over 36,000 feet. The quartzites, siliceous 

schists and chloritic slates along the St. Louis river, referred to the 

Huronian, are many thousand feet thick. Upon the St. Louis slates at 

one place the lake Superior red sandstone and conglomerate repose 

unconformably. The Keweenawan eruptiveroeksarebedded. They have 

a very persistent and quite uniform dip and strike in any given locality. 

The layers are seldom less than a foot or two in thickness and aremore 

often many feet thick, so,as to give an exposure an unstratifled appearance. On one side of each layer is a precipitous and somewhat jagged 

ridge, owing to the exposure of the edge of the layers, while on the other 

side the soil descends with the inclination of the bedding.

As to the age of the Copper-bearing series, it can be only said that 

they are older than the lake Superior red sandstone; for when the latter 

is conglomeratic the pebbles are almost invariably derived from the 

Keweenaw series. Also the perfectly horizontal sandstones approach 

in that condition within 15 or 20 feet of the dipping crystalline rocks; 

and from this it is assumed that they unconformably overlie them. At 

Black river falls on the lower Black river, at the gorge of Copper creek, 

and along the west bank of Middle river, the horizontal sandstones are 

found, in approaching the eruptives of the Copper-bearing series, to become uptilted, brecciated, and in some cases conglomeratic, and sometimes wholly lose their structure. The eruptives in all these cases dip 

away from the uptilted sedimentary rocks.

CHAMBERLIN and STRONG-, 139 in 1880, describe the geology of the 

upper St. Croix district. The Keweenaw series is composed of two 

classes of rocks, massive crystalline beds which owe their origin to the 

succession of outflows of molten rocks, and conglomerates, sandstones 

and shales derived from the wear of these igneous rocks and from the 

older formations. They are in part interstratified with the igneous 

rocks and in part overlie them. The eruptives are mainly diabase and 

diabase amygdaloid, although melaphyre is found. The Keweenawan 

beds were deposited in essentially a horizontal condition, were bent into 

their present trough-like form, and eroded, and upon their upturned 

edges was deposited the Potsdam sandstone. This is shown by the fact 

that at St. Croix falls the horizontally stratified sandstone is found within a few feet of an exposure of highly inclined Keweenawan melaphyre 

containing numerous fragments derived from it. This sandstone has 

characteristic Potsdam fossils. At one place near the falls'the Potsdam is
VANHISB.] LAKE SUPERIOR REGION. 115

found directly superimposed in a small gorge upon the melaphyre. The 

melaphyre is cut by vertical planes of division which are quite smooth 

and uniform; but there is another persistent set which is much less 

smooth, but persistent and constant in direction. These planes are 

usually in detail slightly uneven and undulatory, and separated by several feet. They are believed to represent the dip of the igneous beds. 

It is upon the persistence of these inclined beds, taken in connection 

with their parallel lithological habit, that the determinations of dip are 

made. Outside of the district the northward dipping diabase is found 

on one side of the Numakagon river, while upon the other is seen the 

Laurentian granite.

BROOKS,HO in 1880, gives the geology of the Menominee iron region. 

The Lower Silurian sandstone is found capping the older rocks near 

lake Eliza. The Laurentiau granite, gneiss, and crystalline schist series 

is not Subdivided. No limestones, dolomitic marbles, conglomerates, 

calcareous or arenaceous chloritic schists are considered as belonging 

to the Laurentian system. It is not certain whether this series occurs 

in Wisconsin within the area surveyed.

The Huronian series is divided into lower, middle, and upper divisions. The lower division comprises the lower quartziteof great thickness, the great marble formation, and the great iron ore horizon containing magnetic, hematitic, and jaspery schists as well as deposits of 

iron. The middle Huronian comprises quartzites, clay-slates, and obscure soft schists. The upper Huronian includes mica-schists, gneisses, 

and granite, the last of which may possibly be eruptive, but is the 

topmost member of the Huronian succession. Interstratified with the 

Huronian are diorites, diabases, gabbros and greenstones, and greenstone schists, which are believed to be conformable beds of metamorphosed sediments. They are never found in the form of dikes. The 

thickness of the Huronian in the Menominee is not far from 10,000 to 

15,000 feet. There is great difficulty in ascertaining exactly the thickness on account of the sharp folds, where thick beds double back upon 

themselves. This especially affects the quartzites, clay-slates, and 

greenstones. The relative proportions of the different kinds of rocks of 

the Huronian and a correlation of the successions in various districts of 

the Menomiuee are given, and the twenty members (including the upper 

granite) are correlated in detail with successions north of lake Huron, 

and in the Marquette, G-ogebic, Peuokee, and central Wisconsin regions. 

The resemblance between the Marquette, Menominee, Sunday Lake, 

and Peuokee series are so numerous as to point unmistakably to their 

having been formed in one basin under essentially like conditions. 

Detailed sections and maps of the rock exposures are given at numerous 

points. The youngest Huronian member, the granite, has a wide extent. 

While this is true, granite dikes are rare in the Menominee Huronian 

and have never been observed in the Marquette series. No rocks 

affording the slightest suggestion of conglomeratic structure have been
116 PRE-CAMBRIAN ROCKS OP NORTH AMERICA. [BULL. 88.

found in the Laurentian, its rocks always being much metamorphosed 

and often so much as to destroy all traces of bedding. Underlying the 

quartzite at Sturgeon river falls is a schist-conglomerate which has 

numerous pebbles of what appear to be granite and gneiss from the 

adjacent Laurentian. In the Pine and Poplar river regions is found 

conglomeratic quartz-schist containing micaceous iron and magnetite. 

In the Commonwealth section are included quartz-schists which are 

conglomeratic, containing pebbles of white quartz and jasper. There 

are also found in the upper beds of the Huronian, conglomeratic micaceous quartz-schists. At various places granites and gneisses overlie 

conformably the younger Huronian schists, into which they send dikes. 

As the evidence of bedding is rare, it is possible that toward the end 

of the Huronian period~there was a great eruptive overflow of these 

rocks. Cutting the Laurentian rocks in all directions are dike-like 

masses of granite and greenstone. The abundant greenstone dikes of 

the Laurentian are much more common than in the Huronian, and 

resemble the Huronian bedded diorites. It is suggested that these 

dikes have afforded the material for the greenstones and related schists 

of the Huronian. May not also considerable of the magnetite come 

from the same source?

WRIGHET, 141 in 1880, in describing the western and southern extension 

of the Menorninee range, states there can be no doubt that the granite 

is younger than the lower Huronian. This latter dips under the former, 

and veins of the former penetrate the latter, but whether it belongs to 

the lower Huronian is an open question.

STRONG-, SWEET, BROTHERTON and CHAMBERLiN, 142 in 1882, further 

describe the quartzites of Barren and Chippewa counties. They are 

found in several localities to contain beds of conglomerate, to have not 

infrequently distinct bedding, and to contain locally beds of pipestoue.

KING-,143 in 1882, describes the rocks of the upper Flambeau valley. 

They are found to be mainly granite, gneiss, hornblende-schist and 

mica-schist, and are all referred to the Laurentian.

IRVING- and VAN HiSE,144 in 1882, describe the crystalline rocks of 

the Wisconsin valley. The crystalline rocks here found are a great 

series of schistose gneisses. Alternating with these are finer grained 

and more highly lamellar schists. Intersecting the gneiss are dikes 

of various basic rocks, while structureless masses of granite, presumably intrusive, are also found. In the vicinity of Wausau are argillaceous quartz schists and quartzites, which on lithological ground may 

be referred to the Huronian, although of the structural relations of these 

rocks with the Laurentian gneisses nothing is known.

CHAMBERLiN, 145 in 1883, gives a systematic account of the geology 

of Wisconsin. The rocks of Laurentian age are mainly of the granitic 

type, consisting largely of granites, gneisses, syneites, hornblendic, 

micaceous, and chloritic schists, with allied rocks. These are associated 

with igneous diabase, diorites, and similar rocks. This series is re-
VANHISE.] LAKE SUPERIOR REGION. 117

garded as a sedimentary accumulation, on the grounds (1) of foliation 

and stratification 5 (2) of the alternating bands of varying chemical constitution ; (3) of the verging of one kind of rock into another laterally; and 

(4) of the presence of kinds of rocks not known to be produced by 

igneous agencies. The thickness of these sediments is enormous. An 

estimate of 30,000 feet is probably not too great.

The calcareous and carbonaceous beds of the Laurentian of Canada, 

as well as the Archean limestones and iron ore beds of New York, are 

considered to be Huronian rather than Laurentian, and if this is so, 

there is present in the Laureutian no positive evidence of life, although 

i investigations in the future may reveal evidences of organic beings. Th e 

development of life in the Primordial is so abundant as to lead.to the 

conclusion that for its evolution to this degree of perfection a vast 

prior period of time was required-which probably would carry the life 

well down into the Laurentian series. It is further suggested that the 

abundance of alkaline rocks in the Laurentian may be due to the effects 

of life in the Laureutian ocean.

Between the Laureutian and Huronian periods the Laurentian beds 

were closely folded; the sediments were changed by metamorphisni to a 

thoroughly crystalline condition, and the series was profoundly eroded. 

About the thus formed Laurentian isles was deposited the Hurouiau. 

This comprises .the Penokee series, the Menominee series, the Baraboo 

quartzites, the quartz-porphyries of central Wisconsin, the quartzites 

and catliuite of Barron and Chippewa counties, and the iron-bearing 

series of Black river falls. These series consist for the most part of 

limestones, slates, sometimes heavily carbonaceous, quartzites, hematitic and magnetitic schists, mica-schists and diorites. The presence of 

limestones, carbonaceous shales, and iron ore are taken, as the evidence 

of life. After the deposition of the Huronian it was upheaved, metamorphosed and eroded before the beginning of Keewenawan time, 

although the unconformity between the two series in Wisconsin Is 

but slight and the above changes were only partially accomplished 

when the Keweenawan eruptions began. The metarnorphisin was less 

in degree than that which has affected the Laurentian strata, but is 

more intense than that which the Keweeuawan series has suffered. It 

was not in general sufficient to obliterate the original grains and pebbles, nor to destroy ripple and rill marks. In the Huronian strata are 

igneous beds and dikes of gabbros, diabases, and diorites, the age of 

which is not certain. They may be, so far as yet known, in part contemporaneous and in part subsequent, or wholly the one or the other.

The rocks of the Keweenawan period consist of interstratified igneous and sedimentary beds; the former mainly diabases, with some 

gabbros, inelaphyres, 'and porphyries; the latter conglomerates, sandstones, and shales, derived mainly from, the igneous rocks. The maximum thickness is about 45,000 feet, of which the upper 15,000 feet is 

sedimentary. The bottom of the lake Superior basin was gradually
118 PRE-CAMBEIAN ROCKS OF NORTH AMERICA. [BULL.'86.

subsiding during the time of the formation of these beds. While tilted, 

they are not contorted or metamorphosed. There is in this period no 

direct evidence of the existence of life. Over the great conglomerate 

of the Penokee and Porcupine mountain regions is a black shale that 

simulates those of later ages formed in association with life. After 

the close of the Keweenawan period, before the Potsdam sedimentation 

began, there was a period of erosion. How great this interval was has 

not yet been determined; quite possibly the lower Cambrian formations of Great Britain and Bohemia bridge the entire interval.

iRViNGr,146 in 1883, gives a systematic account of the lithology of 

Wisconsin. Among the eruptive rocks are placed diabase, melaphyre, 

gabbro, norite, diorite, peridotite, syenite, porphyry, and granite. 

Among the schistose rocks are gneiss, mica-schist, hydromica-schist, 

actinolite-schist, tremolite-schist, hornblende-schist, augite-schist, chlorite-schist, talc-schist, magnetite-schist, hematite-schist, quartz-schist, 

quartzite in part, chert1 schist, and jasper-schist. Among the half fragmental rocks are quartzite, clay-slate, and novaculite. The explanation of the origin of gneiss or lamellar granite by metamorphism, the 

structure being regarded as residual sedimentation, is regarded as unsatisfactory. Many rocks which have been called metamorphic are 

placed as eruptive, and it seems not improbable that the same origin 

is to be attributed to some rocks with a strongly developed schistose 

structure. The hornblende-schists are regarded as altered forms of 

augite-schists.

WooSTER, 147 in 1884, describes, upon the St. Croix river near Osceola 

mills, the Potsdam sandstone carrying fossils, which grades down into 

a conglomerate containing pebbles from the Keweenawan, Laurentiau,

and Huronian series. The sandstone and conglomerate rest unconformably upon the underlying Keweenawan rocks.

FULTON, 148 in 1888, describes the Huronian rocks of the eastern Menominee region as consisting of three formations. The basal formation 

is a crystalline siliceous limestone at least 1,200 feet thick, which outcrops at many localities along the range, especially north of the Norway, 

Quinnesec, and Chapin mines. The. next group, estimated at a thousand feet in thickness, is the Quinnesec ore formation. It consists of 

siliceous or jasper slates, largely impregnated with iron oxides. These 

are succeeded by argillaceous hydromica slates and flesh-colored slates. 

This formation embraces the deposits of iron ore. The third formation 

is a series of dark gray, slaty, or schistose rocks, with occasional 

quartzose bands, having a thickness of 2,000 feet, and is called the lake 

Hanbury slate group. Detailed sections at the East Vulcan, Curry, 

Norway, Cyclops, and Quinnesec .mines are described. In some cases 

the ore is associated with the Potsdam sandstone, which rests unconformably in a horizontal position upon the flexed and denuded Huroniau 

rocks. The iron ore beds in the Huronian are generally associated 

with aluminous slates or soapstones.
LAKE SUPERIOR REGION. 119 

SECTION V. WORK OF THE MINNESOTA GEOLOGISTS AND ASSOCIATES.

EAMES,149 in 1866, mentions different crystalline rocks as occurring 

t many points in northeastern Minnesota.

EAMES, 150 in 1866, describes in Minnesota various granitic, igneous, 

nd metamorphic rocks. The most prevalent rocks found in the northam part of the state are granite, porphyry, hornblende slates, siliceous 

slaves, trap, greenstone, talcose slate, primitive schistose rock, gneiss, 

. nnd Potsdam sandstone. The rocks of the Upper Mississippi river are 

described. At Pokegaina falls the rock is a quartzite belonging to the 

Potsdam. There is also found along the river jasperoid rock with iron 

ore and argillaceous slate. In Stearns county are numerous exposures 

of granite. The varieties of rocks in the Vermilion lake district are 

found to be very numerous.

HALL ( JAMES),151 in 1869,,finds in the vicinity of New Ulm, on the Big 

Cottonwood river and on the Little Cotton wood, extensive exposures 

of quartzite. At New Ulm the rock is shown to be a metamorphosed 

quartz rock or conglomerate. This rock is succeeded below by compact quartz rock, with beds of syenite, which graduate still lower into 

purple or reddish quartz rock in distinct layers, alternating with shaly 

seams. The quartzite of this region has a thickness of not less than 

1,500 feet. At Eedwood falls are found gneiss and granitic 'rocks of 

Laurentian age. The quartzites are regarded as of the age of the 

Huronian of Canada and .equivalent to the quartzites of Wisconsin;

WHITE, 153 in 1870, describes the quartzites of Iowa, Minnesota, and 

Dakota. They are completely metamorphosed, intensely hard rocks, 

although the lines of stratification are distinct and there are frequently 

seen distinct ripple marks upon the bedded surfaces. Not infrequently the quartzite is conglomeratic. In them no fossils have been 

found. They are, however, regarded as belonging to the Azoic age because of their complete metamorphic character, because of their disturbed condition, and because "the Lower Magnesian limestone at New 

Ulm rests upon the quartzites unconformably, and in this part of North 

America no disturbances are known to have oceurred between the commencement and close of Paleozoic time.

WINCHELL (N. H),15b in 1873, states that the granitic, and metamorphic rocks occupy a great portion of the state of Minnesota 

These are regarded - as Laurentian and Huronian. Their lithological 

and mineralogical characters are complex and variable. The original 

nucleus was granite and syenite, and around these are arranged the 

metamorphosed slates and gneisses in upturned or even verticaFbeds, 

while intercalated with them, are numerous injected beds or dikes of 

trap. The Sioux quartzite and those of New Ulm are placed as a part 

of the Potsdam sandstone. The Potsdam was laid down before the 

close of the volcanic disturbance, for the St. Croix beds of later age 

rest unconformably upon the Laurentian as well as upon the upturned
120 PRE-CAMBEIAN EOCKS OF-NORTH AMERICA. [B0ix.8«.

beds of the Potsdam. In lithological character the Potsdam beds dif-> 

fer from those of the St. Croix, being hard and vitreous and usually of a 

red color. The Potsdam has a thickness of at least 400 feet. j

WINCHELL (N. H.), 154 in 1874, gives details as to the geology of tW 

Minnesota valley. . The quartzites in the vicinity of New Ulm and_R j 

stone, referred to the~:Potsdam? are conglomeratic- in places. .In tu? 

valley there are quite numerous outcrops of granite which are 

times'cut by trap dik6s. At Granite falls there are sudden 

from real granite to hornblende-schist. - , - '?</ 

STRENa and KLOOS,15? in 1877, describe in the -Upper Mississippi a. 

set "of granitic, syenitic,Mioritic, and rgabbro-like rocks which are referred to the Laurentian, while north of these, is a zone of metaniorphic 

schist mica-slate, talc-slate,' and clay-slate with gneiss-like rocks, 

which may be Huronian. South of Vermilion lake-is a region of granite, gneiss, and crystalline slate which belong, to the Laurentian formation-, while occupying a wide extent of country about the St. Louis .. 

river are roofing slates and quartzites which are -probably; the representative of the Huronian. The igneous rocks.at: the west end of lake 

Superior are without doubt of Potsdam, age. On the St. Croix river is' 

_ a melaphyre which lies unconformably below a sandstone and conglomerate bearing fossils of Lower Silurian age, which relation .points to 

the Huronian age of the -melaphyre.

WINCHELL (iT. -H.),156 in 1878,"describes the crystalline rocks "along 

the Northern Pacific railroad. Syenites and^ granites occur at Little 

falls on the Mississippi, and at Thompson on the St. Louis river are 

slates, the former varying into a mica-schist. In Pipestone and Kock - 

counties are large exposures of quartzite which are lithologioally like, 

those of New TJlm, and like them are placed in the Potsdam. ' - WINCHELL (K H.), 157 in 1879, gives the geological results of an 

examination of the northeastern part of the state of Minnesota. The 

formations that compose the coast.line of 'lake Superior include, in descending order, (1) metamorphic shales, sandstones, and quartzites cut . 

by dikes and "interbedded with igneous rocks, perhaps Sir William 

Logan's Quebec group. . (2) Sandstones, metamorphosed- into basaltiforra red rock,interstratified with igneous rock along the Palisades and 

at Black point. (3) A quartzose conglomerate at the Great-Palisades 

and at Portage bay island. (4) The quartzites and slates of Grand 

Portage bay. . (5) The jasper, flint, and iron-bearing belt of Gunfliht 

lake, Yermilion Jake and Mesabi. (6) The slates and schists which the. 

Canadian geologists designate Huronian. (7) Syenites, granites and 

'other rocks which have .been classed as Laurentian. (8) The igneous 

rocks known as the Cupriferous series. "* The Cupriferous series seems 

to overlie several formations unconformably, and is interstratified with - 

some of the later, and especially with ISTos. Land 2. 

WINCHELL (N. H),158 ' in. 1880, describes the Cupriferous series of 

Duluth. At Duluth the most Important rock is the gabbro. This is
VANHISE. LAKE SUPERIOR REGION. 121

intimately associated with a syenitic granite which is a metamorphic 

'rock, all stages being seen, from the perfectly crystalline granite to the 

unchanged sedimentary layers. The Cupriferous series is regarded as 

t, Potsdam.

-'UPHAM,159 in 1880, describes granites and gneisses at numerous localia tes in the Minnesota valley. In the conglomerate opposite New Ulm 

< > jid in the quartzite at Eed stone are found numerous pebbles of quartz 

 *.nd jasper, but no granite-pebbles are seen, although it outcrops close 

So the west.

HALL, (C. W.), 160 in 1880, describes the rocks between the mouths of 

Poplar and Devil's track rivers on lake Superior to be dark colored 

basic rocks of igneous origin belonging to the Cupriferous series, with 

the exception of a few beds of sandstone and conglomerate interbedded 

with the igneous rocks. The Sawteeth mountains are formed as a result of combined igneous action and the folding of sedimentary strata 

and erosion.

WINCHELL (N. H.),161 in 1881, gives many details as to the rocks of 

northeastern Minnesota. At Pigeon point is a massive bedded or jointed 

formation like that at Duluth, with which it may be parallelized. The 

latter belongs to the Cupriferous series and the former to the Animikie, 

so that the Animikie appears to be a downward extension of the Cupriferous. At Mountain lake the hills are short monoclinals of gray 

quartzite, with beds of argillaceous and black slate, dipping to the 

southward usually at an angle of 8° or 10°, and covered with a greater 

or less thickness of trap rocks. In beds generally less than 50 feet, 

but sometimes 150 feet thick, the trap and slate dip together, so that 

the hills have gradual slopes toward the south, and steep or perpendicular slopes toward the north. The quartzite must be an immense 

formation, as it is seen at Grand portage and all over Pigeon point, 

and on the islands of the point. The quartzite formation of Gunflint 

lake seems to graduate downward into the irony and carbonaceous 

Gunflint beds. A greenish, schistose, porphyritic rock cut by veins of 

milky quartz is found in nearly a vertical attitude on Gunflint lake. 

This is supposed to be the Canadian Huronian, and underlies the 

quartzite and Gunflint beds apparently unconformably; at least, it is a* 

distinct formation from the Grand portage slates. The quartzite is locally 

a quartzite conglomerate. The Knife lake serpentinous quartzite is 

,regarded as Huronian. On the south side of Yermilion lake are beds of 

jasper and iron which are regarded as the equivalent of the Gunflint 

beds. These are conformable with the magnesian schists and slates, 

which are in a vertical attitude. They pass down into the schists, and 

in places the schists and schistose structure penetrate the jasper and 

iron. It is suggested that the apparent conformity between the ferruginous beds and underlying slates and schists is only a superinduced 

one, the original bedding, which may have been nearly horizontal, having been obliterated by the change;
122 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

WINCHELL (N. H.), 163 in 1881, describes the Cupriferous series of 

Minnesota as having a wide extent. In passing from the shore of lake 

Superior it gradually becomes more changed and crystalline. The 

tilted red shales, conglomerates, and sandstones at Fond du Lac are 

the same as those associated with the igneous rocks all along the shore. 

At Fond du Lac they lie on a white quartz pebbly conglomerate a few 

feet in thickness, which rests unconformably on the roofing slates of the 

Huronian, the same formation that succeeds to the red rock formation 

at Ogishki Manissi and Knife lakes, northwest of Grand Marais. The 

Cupriferous series differs from the Upper Laurentian or dorian only in 

the absence of beds of limestones, but, as the lake Superior Cupriferous 

is Cambrian or Lower Silurian, it is inferred that the so-called Upper 

Laurentian, containing Eozoon canadense, is really Cambrian or Lower 

Silurian.

WINCHELL (N. H.),163.in 1882, continues his description of localities. 

At Fond du Lac the detailed succession of sandstones and shales is 

given. The nint and jasper formations of Gunnint lake appear to be 

in apparent unconformity with the underlying slates and syenites. On 

Ogishki Manissi lake is found a great conglomerate. This conglomerate 

carries large rounded pieces of the Saganaga granite, which proves 

the greater age of that granite and the unconformability to it of the 

conglomerate. The conglomerate also contains red jasper.

The descending succession in northeastern Minnesota is (1) the horizontal quartzites and slates running from Grand portage to Gunnint lake; 

(2) the conglomerate; (3) jaspery and calcareous Gunnint beds; (4) 

gray marble; (5) the tilted slaty Ogishki Manissi conglomerate; (6) 

amphibolitic and chloritic slates;. (7) mica-schists alternating with syenite; (8) syenites and granites of Saganaga and Gull lakes. As to 

whether the Gunnint beds belong with the schistose and tilted slates 

and conglomerates of Ogishki Manissi lake is an open question, although 

there are several things which indicate that they belong to the same 

series. The gabbro is found to have a widespread extent. It is suggested that if this gabbro and the associated red gneisses belong to the 

Cupriferous, the Minnesota and Wisconsin quartzites, as well as the 

red, gneisses of the Upper Mississippi valley, may also belong to this 

series. The red syenite of Beaver bay is a metamorphosed conglomerate which was brecciated and mingled with the trap. This red rock 

was fluidized so as to intrude itself in the form of belts and veins. A 

conglomerate at Taylors falls, on the St. Croix, contains water-worn 

bowlders and traps of the region, but the superposition of the conglomerate on the trap can not actually be seen. This sandstone is fossiliferous.' It is concluded that the Potsdam is represented by the copperbearing series, while the underlying Aniinikie is equivalent to the 

Taconic of Emmons.

UPHAM,104 in 1884, describes the crystalline rock outcrops in central 

Minnesota.
VANHISE.] LAKE SUPERIOR REGION. 123

CHESTER,165 in 1884, describes the rocks of the Mesabi and Vermilion 

iron ranges. The slates and schists on the south side of the Mesabi 

range are nearly horizontal. The rocks here found are precisely like 

those of the Penokee region of Wisconsin, and the two series bear the - 

same relation to the Hnronian series. The iron ore at Vermilion lake 

is found in connection with jasper and quartzite and is intimately 

bedded with the country rock, chiefly sericite-schist, standing in nearly 

a perpendicular position. These rocks are the representative of the 

Michigan and Wisconsin iron deposits, and there is no doubt that they 

belong to the Huronian. The Vermilion deposits bear the same relations.to the granite as do those of Mesabi, and they are regarded as the 

same formation.

WINCHELL (N. H.),16G in 1884, gives the general succession of rocks 

in northeastern Minnesota, in descending order, as follows: (1) Potsdam, including the Keweenawan sandstones, shales, and conglomerates, 

changed by igneous gabbros and dolerites locally to red quartzites, felsites, quartz-porphyries, and red granites. (2) Taconic group, including the Animikie series, the Gunflint beds, the Mesabi iron rocks, the 

Ogishki Manissi conglomerate ("?), the Thompson slates and quartzites, 

and the Vermilion iron rocks. (3) Huronian group (?), including magnesian soft schists, becoming syenitic and porphyritic, found on the 

north side of Gunuint lake, along the national boundary, and at Vermilion lake. (4) Montalban (*?), including mica-schists and micaceous 

granites about Vermilion lake and on the Mississippiriver. (5) Laurentian, including massive hornblende-gneiss and probably the Watab and 

St. Cloud granites. .This succession is parallelized with those of other 

writers given for the northwestern States.

WINCHELL (IsT. H.) and UPHAM, 167 in 1884 and 1888, give detailed 

geological maps and descriptions of many of the counties of Minnesota, 

which include the Laurentian gneisses and granites of the Mississippi 

and Minnesota rivers, the slates of the Upper Mississippi, the quartz, 

ites and conglomerates of Cottonwood, Pipestone, Rock, Brown, and 

Nicollet counties, which are regarded as Potsdam sandstone. The copper-bearing traps and conglomerates of Chisago and Pine counties are 

placed as Lower Cambrian. These reports contain nothing as to structural relations not found in the annual reports.

WINCHELL (N. H),168 in 1885, finds between Two harbors and Vermilion lake two rock ranges, the first being Mesabi proper and the 

second the Giant's range. Resting unconformably upon the syenites of 

Giant's range are the Huronian conglomerates and greenstones of Vermilion lake, while south of this range are the slates and quartzites of 

the Animikie, overlain by the gabbro and red granite of the Mesabi 

range, which is in turn overlain by the trap rocks of the Cupriferous 

series. The Huronian is represented as resting conformably below the 

Animikie, although not appearing at the surface. There are three ironore horizons, the titanic iron of the gabbro belt; the iron ore of the
124 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL.86.

Mesabi range belonging in tlie Animikie, and the hematite of the Yermilion mines, which seems to be the equivalent of the Marquette and 

Menominee iron ores.

WINCHELL (N. H.), 1C9 in 1885, finds in the red quartzite at Pipestone 

two fossils, Lingula calumet and Paradoxides barberi, which are taken 

as indicative that this formation, as well as the Sioux quartzite of Iowa 

and Dakota, the Baraboo quartzites of Wisconsin, the quartzites of 

southwestern Minnesota, as well as the associated red gneisses, felsites, 

and felsite-porpkyries, are all Primordial.

TJPHAM,170 in 1885, gives descriptions of the quartzites of Minnehaha 

county, Dakota. These arQ not infrequently ripple-marked and conglomeratic; they are like the quartzites of Pipestone county in Minnesota, and, like them, are placed in the Potsdam.

WINCHELL (N. H),m in 1885, divides the crystalline rocks of the 

northwest into six groups, in descending order: (1) A granitic and 

gabbro group, which is a part of living's Cupriferous, and is by Hunt 

parallelized with the Moutalban. It includes rocks which have passed 

for typical Laurentian; while the gabbros are eruptive and are like the 

Upper Laurentian or Norian of Canada. The granites and gneisses 

show evidence of metamorphic origin. Below the granite and gabbro 

is (2) a mica-schist group. This is penetrated by biotite-granite. (3) 

Is the black mica-slate group, which often contains graphitic schists, 

in which are such ore deposits as the Commonwealth mine of Wisconsin. (4) Is a series of obscure hydromicaceous and greenish raagnesian 

schists, along with quartzites and clay slates, with which are the more 

important bodies of heinatitic iron ores? including those at Marquette 

and the magnetic belt at Penokee. (5) Is the great quartzite and marble 

group. It includes the marble of Menominee and marble and lower 

quartzite of Marquette, the great, conglomerate of Ogishki Manissi lake 

and the lower slate-conglomerates of Canada. In. (6) are the granites 

and syenites with hornblende-schists. This is the lowest recognized 

horizon of the Laurentian. . Nos. 3,4, and 5 together are the equivalent 

of the Taconic system, 3 being the equivalent of the Animikie, while 5 

is the equivalent of the Huronian of Canada. This succession is compared with the successions of Brooks and Irving in Michigan and Wisconsin.

WINCHELL (ALEX.),t72 in 1887, gives detailed observations made on 

an extensive trip in northeastern Minnesota. The region presents a 

series of schists flanked on the north and south by massive crystalline 

rocks. In the western part of the district these rocks are gneissic on 

both sides, but to the east the gneissic rocks on the south are replaced 

by gabbro and greenstone. The schists and bedded crystallines stand 

in a nearly vertical attitude, having a persistent and uniform strike 

and dip, the latter oscillating from 80° to the north to 80° to the south. 

The rocks are sericitic, chloritic, micaceous, and hornblendic schists, and 

argillites and graywackes. The schists grade into the gneissic rocks,
VANHISE.] LAKE SUPERIOR REGION. 125

there being nowhere an abrupt passage from one class to the other. In 

the passage from the schists to the gneisses there is first an increase in 

frequency of ramifying veins, then lumps of gneiss or granite in the 

schists, and next interstratification of the schists and gneisses. The 

conglomerate at Ogishki Mauissi lake, which attains an enormous development and contains varieties of granitic and quartzose bowlders, as 

well as flint, jasper, and other substances, is regarded as a local phase 

of the schists, as the bowlders are interbedded with the flinty argillites 

and sericite-schists. The entire system, of gneisses and schists is regarded as belonging to one structural system, as they all possess a 

common dip and pass by gradations into each other. The iron-bearing 

rocks are interlaminated with the country schists, and while they exhibit much persistence, they do not persist without interruption. In 

structure the region is a simple synclinal fold, the strata of which have 

a thickness of 106,204 feet. The succession from the bottom upward is 

granite, gneiss, micaceous and hornblendic schists, gray wacke, argilliteschist bearing conglomerates, and sericitic and chloritic schists bearing 

iron ores. As the plainly fragmental rocks grade by imperceptible 

stages into the gneiss and granite, the whole is regarded as a sedimentary series. While granite pebbles are found in the conglomerates, 

this is not the underlying granite, as many of the fragments differ in 

character from the inferior granite.

WINCHELL (N. H.),1T5 in 1887, gives very numerous details as to the 

geology of northeastern Minnesota. At several places there are transitions between the granite gneiss and a fine grained mica-schist. In 

the syenite are sometimes found angular fragments of micaschist. The 

Yermilion group is denned as including the lower portion of the complex series of schists designated as Keewatin by Lawson. It embraces 

the mica-schists and hornblende-schists of Yermilion lake and their 

equivalents, and lies between the gray wackes on the one side and the 

basal syenites and granites on the other.

The iron ores of Minnesota are at three horizons. At the top are the 

titaniferous ores, which are associated with the gabbro and constitute 

what is locally known as May hew Iron range, and is found from this 

range at many points all the way to Duluth. The nontitaniferons magnetic ores occur at several localities associated with hematite ores and 

included in a quartz-schist. These ores are comparable to those of the 

Penokee-Gogebic Iron range on the south side of lake Superior, and 

those of Black river falls in Wisconsin. Adjacent to Yermilion lake are 

hematite ores associated with jasper, which are inclosed in a schist-, the 

bedding of which stands vertical. This schistose rock is probably of 

igneous origin, and in its relations to the jasperoid rocks it fills all their 

cavities, overlying them unconformably, and holding fragments of the 

jasper; all indicating its later origin. This igneous rock passes into 

achlorite-schist, and this into the sericite-schists and graywackes, which 

show unmistakable evidence of an aqueous arrangement. The jasper-
126 PEB-CAMBEIAN ROCKS OF NORTH AMERICA. [BULL. 86.

old hematite is a sedimentary rock and not an eruptive as has been supposed by Wadsworth. The rock was not, however, deposited in its 

present condition. The beds have been upturned, folded, crushed, and 

affected by intense chemical action. The ore is regarded as a result of 

chemical or metasomatic change. The general succession from above 

downward is as follows: (1) gabbro; (2) diabase dolerite. These rest 

unconformably upon the lower members. (3) Beddish gneiss and 

syenite, which includes the Misquah hills, White Iron lake, and the 

Giant's range (Mesabi heights). This is a case of a fusion of sedimentary beds in situ, although it is not generally complete. (4) Graywacke, 

sericite-schist, argillite, quartzite, and jaspilite, which occur about Vermilion lake. (5) Mica-schist, hornblende-schist, and diorite. The Vermilion group. (6) Mica-schist and granite veined .with syenite and 

granulite. (7) Lower syenites and gneisses, generally regarded as Laurentian. Nos. 3 to 7 are conformable, and Nos. 4 to 7 graduate into 

each other.

There is reason for believing that the Aniniikie rocks overlie the 

greenstone No. 2 and underlie the gabbro, No. 1, of the above succession.

WINCHELL (N. H.),174 in 1888, finds the Upper Huronian quartzites 

to be so similar to those of Pipestone, Gottonwood, and other counties 

in Minnesota that the former are regarded, with the latter, as Huronian. 

The Aniinikie on Gunflint lake, while not found in exact superposition 

on the Keewatin, bears such relations as to render it probable that the 

two formations are discordant. A short distance north of the Aniniikie 

the Keewatin rocks are found with a dip of 80°, and these a little farther to the north grade conformably into the crystalline schists of the 

Vermilion group, and these still farther to the north by transition pass 

into the'gneisses and syenites of the Laurentian. The Aniinikie rocks 

are found resting unconformably on the gneiss west of Gunflint lake. 

The gabbro is observed overlying the Aniinikie at many places, the 

Pewabic quartzite, the Keewatin rocks north of Gunflint lake, and the 

syenite-gneiss north of Flying Cloud lake.

In passing from Gunflint lake the Auimikie is found to nave a clip as 

high as 30°. Near Gobbemichigomog lake there is a gradation from the 

flat-lying Animikie to rocks in a broken and tilted condition, and from 

these into the Ogishki Manissi conglomerate, with which they are interstratified. There is also extending from Stuntz island in Vermilion lake 

past Ely to near Ogishki Manissi lake an older schistose eruptive-loolSng 

conglomerate associated with the Keewatin schists, and therefore older 

than the Ogishki conglomerate. The beds on the north side of Gunflint lake resemble those on the south side of the Giant's range and belong in the same stratigraphical position near the beds of the Animikie. 

The gneiss is regarded as a metamorphosed sedimentj because of the 

gradation of the Keewatin beds into it, and because it cuts through 

and is interstratified with the Keewatin. The Keewatin schists
VANHISB.] LAKE SUPEEIOR REGION. 127

are interstratifled eruptives and sedimentaries, as is the Cupriferous series. On Ke"ke"kabik lake there is an extension of the Ogishki 

Manissi conglomerate westward. The green schist conglomerates here 

found are apparently of about the same date as the Ogishki conglomerate or else its immediate conformable successor. The Animikie 

' slates associated with this green schist conglomerate are also in conformable succession to the green schists, but it is likely that this conformity would not be found in the vicinity of the old volcanic vents.

WINCHELI, (ALEX.),175 in 1888, finds upon Wonder island in Saganaga 

lake a conglomerate which contains abundant rounded pebbles in a 

groundmass of syenite. The lower limit of the conglomerate is quite 

abrupt, and whether it overlies the syenite or grades into it is uncertain, but it is figured as overlying the syenite. The syenite is regarded 

as erupted after the conglomerate existed and the conglomerate was 

not laid down on the solidified syenite. The Animikie slates are found 

resting unconformably upon vertical schists, gneisses, and syenites at 

several points on Gunflint lake, 2 miles west of Gunflint lake, and on 

the north side of Epsilon lake. On the west side of Sea Gull lake the 

conglomerate and syenite are interbedded. This conglomerate is 

thought to be comparable with that of Wonder island. On the north 

side of the same lake the syenite contains sharply limited rounded pebbles and irregular masses of hornblendic and diabasic material. On 

Epsilon lake the argillite has schistic planes standing vertical, while 

the bedded structure has a dip of only 23°.

Summing up the succession: At the base are the granitoid and 

gneissoid rocks in three areas, the Basswood, White Iron, and Saganaga 

lakes. These granitic masses everywhere have a bedded structure 

more or less distinct. They are traversed by quartzose and granulitic veins, as well as dikes of diabase. The gneisses and granites 

are flanked by vertical crystalline schists of the Vermilion group. The 

transition from the gneisses to the crystalline schists is never abrupt, but 

is a structural gradation, near the line of junction the beds of gneisses 

and schists occurring in many alternations. Above the Vermilion group 

are the Keewatin semicrystalline schists, the two series being everywhere conformable; but there is a somewhat abrupt change from one 

group to the other, and there is a possibility that the original unconformity has been destroyed by lateral pressure, although such an unconformity is thought improbable. There has been no actual connection 

traced between the Keewatin schists north of Gunflint lake and those 

of Knife lake. The Keewatin schists are almost everywhere vertically 

bedded. When the bedding is obscure this is sometimes due to the 

action of erupted masses, but more often the cause of the metamorphosed condition of the strata is not ascribable to any visible cause. 

The Keewatin schists include graywacke, argillite, sericite-schist, chlorite schist, porphyrellyte schist and hematite. 

The Ogishki conglomerate is placed as a part of the Keewatin system
128 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL.86.

as it is traced by actual gradations into the adjoining argillites. These 

argillites and associated schists are in continuity with the argillites and 

schists of Vermilion lake, while in the conglomerate itself are local developmentsof sericite-schist. The bedding of the con glomerate is nearly 

vertical; its pebbles are metamorphosed; they include numerous varieties, among which are syenite resembling the Saganaga syenite, greenstone, porphyry, red jasper, flint, quartz, petrosilex, ordinary syenite, 

diorite, porphyroid, siliceous schist, and carbonaceous siliceous argillite. 

On structural as well as lithological grounds theOgishki conglomerate 

seems to be a part of the Keewatin, although there are some reasons 

for suspecting it to grade into the Animikie. That the Keewatin schists 

are eruptive is regarded as improbable.

The Animikie series, resting uneonformably upon the Keewatin, 

stretches from Thunder bay as far as Duluth and still beyond to the 

, Mississippi river, and perhaps includes the slates as far west and north 

as Knife lake. The Animikie formation is generally in a nearly horizontal position, the dip not being more than from 5° to 15°. The formation is essentially an argillite, which embraces jaspery, magnetitic, 

hematitic, and sideritic beds. At Gobbemichigomog lake the Animikie, 

represented by the "muscovado," is in its characteristic horizontal 

position, while the vertically bedded terrane underlies it.

For the system of semicrystalline schists subjacent to the Animikie, 

to which the term Keewatin has been applied, Marquettian is proposed. 

The succession of terranes in northeastern Minnesota is, in descending 

order, then as follows: (1) Huronian system, over 4,082 feet thick, including the magnetic group, siliceous group, and argillite group; (2) 

Marquettian system, 27,500 feet thick, including the Ogisliki group, 

10,000 feet thick, the Tower group (earthy schists), 15,000 feet thick, 

and the graywacke group, 2,500 feet thick; (3) Laurentian system, 

89,500 feet thick, including the Vermilion group, over 1,500 feet thick, 

and the gneissic group, over 88,000 feet thick. Total, more than 

121,082 feet.

WINCHBLL (H. V.),176 in 1888, gives detailed observations about 

many localities in northeastern Minnesota. The mica-schist and interbedded gneiss are cut by granite veins at numerous places.

WINCHELL (N. H.), 177 in 1888, maintains that there is a great Primordial quartzite extending from New England through Canada, Wisconsin, and Minnesota to the Black hills of Dakota. It includes the 

Taconic quartzite of Emmons, that of Sank and Barron counties in 

Wisconsin, the Sioux quartzite of Dakota, the quartzites of Minnesota, 

and those of the Black hills of Dakota. At the exhibition in New 

Orleans in 1884 was seen a block of the Potsdam sandstone of the state 

of New York exactly similar to the Pipestone quartzite of Minnesota, 

and as the latter bears Primordial fossils there is no lack of evidence to 

parallelize these outcrops. An examination of the quartzites of the
VANHISE.] LAKE SUPERIOR REGION. 129

Original Huroniau convinced the author of the parallelism of the great 

quartzite there displayed with those of Wisconsin and Minnesota. But 

things that are equal to the same thing are equal to each other, hence 

the Huronian quartzite is no other than the Potsdam sandstone of New 

York, the Eed sandrock of Vermont, and the granular quartz of the 

Taconic.

WINOHBLL (N. H.),178 in 1889, gives a summary of the results of work 

on the crystalline rocks of northeastern Minnesota. In many points the 

conclusions and facts are the same as in the previous reports. The 

Laureutian age is made to include the gneiss, granite, and syenite, but 

excludes the crystalline schists. It is the fundamental gneiss of Minnesota. Associated with this fundamental gneiss are areas of massive 

eruptive syenite which are regarded as due to the hydrothennal fusion 

of the gneissic belts. The gneisses grade into the Vermilion schists, 

which are the equivalent of Lawson's Coutchiching. Along their contact the Laurentian plays the part of intrusive rocks, which is indicative that the opening of Vermilion age was one of violent volcanic 

action. The beds have subsequently been affected by hydrotherrnal 

fusion, which has tended to unify the Laurentian and Vermilion systems.

The Vermilion group passes by conformable transition into the 

Keewatin. The character of the Keewatin rocks indicates that there 

was active volcanic action during the whole period and that the ejectiinenta were received and distributed by the waters of the surrounding 

sea. This is indicated by the alternation of breccias and volcanic material with truly sedimentary strata. The Keewatin is the iron-bearing 

formation. The iron ore is associated with the jaspilite, which is*of a 

sedimentary origin. Parallel with the Keewatin of Minnesota is. the 

serpentine and dioritic group of Eorninger in the Marquette region. 

Above this group in both regions is a profound unconformity.

The Animikie series of Minnesota, bearing iron at one horizon, is the 

equivalent of the Marquette series bearing the iron group of Eominger, 

of the Penokee-G-ogebic series of Michigan and Wisconsin, of the Mesabi 

range in Minnesota, of the Black river iron-bearing schists in Wisconsin, and of the quartzites of the Black hills. All are of Taconic age, for 

the Lower Cambrian is equal to the Taconic, the Huronian is equal to 

the Taconic; therefore the Lower Cambrian is equal to the Huronian.

In the Potsdam sandstone, which is unconformably on the Taconic, 

is included the upper quartzites of the Original Huronian, certain of the 

quartzites of Marquette, the Sioux quartzites of Dakota, and the 

quartzites of Minnesota and Wisconsin. This is also the age of the 

Copper-bearing rocks, which are an alternation of basic and acid eruptions with interbedded sandstones and conglomerates. The great gabbro eruption is later than the beginning of the Potsdam age. Unconformably above the Potsdam is the St. Croix sandstone. 

Bull, 86. 9
130 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86. 

The general succession in descending order is then as follows:

Calcifeimis ...... Magnesias limestones and sandstones ..) 1V1 -, , i i,,;,,, St. Croix......... Sandstones and shales ................. J Dikelocephalus horizon.

Overlap unconformity. 

Potsdam......... Qnartzite, gabbro, red granite, and Keweenawan ................................ Paradoxides horizon.

Overlap unconformity. 

Taconic .... ..... Black and gray slates and quartzites, iron

ore (Huronian, Animikie)..............Olenellus horizon.

Overlap unconformity. 

Keewatin... . (Including the Kawishiwin or greenstone "1 

belt, with its jaspilite), sericitic schists | 

y wackes .............

ihing) crystalline schis"

Eruptive unconformity.

and gray wackes ..................... j

Vermilion ....... (Coutchiching) crystalline schists....... }> Archean.

Laurentian ...... Gneiss

WINCHELL (ELY.), 179 in 1889, gives further observations on the iron 

regions of Minnesota. On the Giant's range the Animikie is found to 

rest upon the syenite. Here is a semicrystalline rock between the 

two, Avhich grades into the syenite. The character of the transition is 

not inetamorphic, but rather fragmental, there appearing to be a certain amount of loose crystalline material which has resulted from the 

decay and erosion of the syenite lying on top of this rock in the bed 

of the sea upon and around which the Animikie sediments were deposited. The coarse detritus grades up into the fine detritus of the 

Animikie. The Animikie beds are found also to rest unconformably 

upon, the upturned edges of the Keewatin schists. The same relations 

are found to prevail in the Birch lake region. The gabbro containing 

ores in the vicinity of Kawishiwi river are found to contain fragments 

of the Animikie slates and quartzites, and is, therefore, of later origin. 

At Gunnint lake the Animikie rests unconiformably upon the Keewatin, 

and is found upon greenstone. The Keewatin schists are largely of 

eruptive origin. The contacts of the jaspilite with the basic schists 

are abrupt and angular, and numerous fragments are found contained in. 

the schists. The jaspilite is regarded as a sedimentary formation which 

was broken up and involved in the eruptions of Keewatin age. The 

Huronian quartzite associated with the magnetite, lying unconformably 

upon the syenite, is believed to lie conformably upon the Animikie slates.

GuANT,lito in 1889, gives geological observations made in northeastern Minnesota. North of Gunflint lake the vertical Keewatin and crystalline schists, with an east and west strike, strike directly across a 

range of immediately adjacent gneisses, the schists showing no evidence of being twisted or bent within 200 feet of the gneiss. In the 

syenites of Gunflint lake are found fragments,of schist, which indicate 

that the syenite is eruptive later than the schists. At Winchell lake 

the syenite upon the top grades down by an apparent transition into
vANmsE.] LAKE SUPERIOR REGION. 131

gabbro. The gabbro is sometimes cut by veins or dikes of syenite, 

which indicates that the latter is of later age, although the syenite is 

generally below the gabbro.

WINCHELL (ALEX.),181 in 1889, maintains that the Saganaga and 

West Sea Gull granite conglomerate before described is produced 

from a fragmental rock by selective metamorphism, the completely 

crystalline gneissoid rocks retaining rounded fragments which are* 

residual clastic material. The conglomerate of Wonder island is not 

one consisting originally of a mass of pebbles over which a fluid 

magma has been poured, for the pebbles are not in contact,- they could 

not have lain where they are before the gneissic magma existed. The 

gneissic magma was present, and it was this which supported the pebbles and prevented their contact. It is, then, contemporaneous with the 

pebbles. The magma must have been plastic, but it was low temperature igneo-aqueous plasticity.

WINCHELL (N. H.), 182 in 1889, in a general discussion of the origin of 

the eruptive rocks, maintains that there are four epochs of basic eruption in Minnesota: first, the Yermilion group; second, those succeeding 

the graywackes; third, those succeeding the Animikie; and fourth, 

those of the Cupriferous formation.

MEADS,183 in 1889, describes the Stillwater, Minnesota, deep well. 

The well, after passing through about 700 feet of St. Croix and Potsdam 

sandstone, passes into rocks which are in every respect identical with 

those of Keweenaw point; hence the KeAveenaw rocks are below the 

light colored sandstones of the northwest. For the first 1,500 feet these 

are brown shales and brown feldspathic sandstones, and these gradually assume the characters of a volcanic detrital tuff amygdaloid 

and finally at a depth of 3,300 feet unmistakable beds of trap were encountered alternating with sandstone beds. At this depth grains of 

native copper were seen in the drillings.

WINCHELL (8. H. and H. V.), 184 in 1889, maintain that the iron ores 

of the Keewatin of Minnesota are not derived from a carbonate, but are 

probably a direct chemical precipitate; for there is no evidence of the 

existence of carbonate of iron at any time, and the nature of the country rock is such as to imply that no carbonates in amounts required 

could have been deposited at the time the rocks were formed.

WINCHELL (ALEX.),185 in 1890, repeats his general conclusions as to 

the stratigraphy in northeastern Minnesota and gives in descending 

order a succession, as follows:

V. The Uncrystalline schists (Animikie, Huronian).

IV. The Semi-crystalliue schists (Keewatin). 9 

III. The Crystalline schists (Vermilion).

II. The Gneissoid rocks.

I. The Granitoid rocks (Laurentian).

WINCHELL (N. H. and H. V.),186 in 1890, state that the iron ores of 

Minnesota are at five different geological horizons, in descending order,
132 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

as follows: (1) The hematites and limonites of the Mesabi range, the 

equivalents of the hematites of the Penokee-Gogebic range in Wisconsin ; (2) the gabbro titaniferous magnetites near the bottom of the rocks 

of the Mesabi range; (3) Olivinitic magnetites, just below the gabbro 

in the basal portion of the Mesabi rocks; (4) the hematites and magnetites of the Vermilion range in the Keewatin formation; (5) the magnetites of the crystalline schists of the Vermilion formation. It is maintained that the upper iron deposits of the Mesabi and those of the 

Peuokee-Gogebic are the equivalents of the Taconic ores of western New 

England.

WINCHELL (N. H.) 187, in 1891, gives numerous additional field observations. The relations of the jaspilite, argillite, and green schist are 

considered, and the argillite at least is regarded as a sedimentary 

rock. The position of the Pewabic quartzite is left uncertain. It is 

considered, however, to overlie the Aniinikie black slate, unless there 

are two great quartzites. This quartzite has heretofore been made the 

parallel of the great quartzite that overlies the Anhnikie unconformably, but it is possible that it runs below it conformably. In the Stuntz 

conglomerate is found a large bowlder which contains pebbles of chalcedonic quartz and quartzose felsite and the porphyrel at Kekekabik 

lake. A study of the ore formation leads to the conclusion that al 

three of the known agencies for rock-forming were intermittently at 

work and concerned in the formation of the iron ore, viz: Eruption, to 

afford the basic eruptive material; sedimentation, to arrange it (in the 

main), and chemical precipitation in the same water, to give the pure 

hematite and the chalcedonic silioa. The great gabbro of the Cupriferous formation is regarded as lying below the Animikie, among other 

reasons, because it lies next to and immediately south of the gneiss of 

the Giant Range without the appearance of any black slate between 

them; and because bowlders of characteristic gabbro, red syenite, and 

quartz-porphyry occur abundantly in the later traps of the Cupriferous.

WINCHELL (1ST. H and H. V),188 in 1891, give an extended treatment 

of the iron ores of northeastern Minnesota and the rocks in which they 

are contained. Excluding the Cretaceous, the rocks here found are 

divided in descending order, as follows: Keweenawan trap rocks, tuffs, 

red .sandstones, and conglomerates (Potsdam1?); Animikie black slates, 

gray, feldspathic sandstones and limestones; Norian gabbro of the 

Mesabi hills, red granite, quartz-porphyry, red felsite; Pewabic quartzite (Granular quartz, Potsdam1?); Keewatin. sericitic schists, graywackes, greenstones, agglomerates, jaspilite; Vermilion mica-schists 

and hornblende-schists (Coutchiching?), Laurentian sedimentary, 

gneissic and eruptive, massive or porphyritic. The Keweenawan to the 

Pewabic inclusive are placed in the Taconic, and the Keewatin to the 

Laurentian inclusive in the Archean or Azoic.

The jaspilite and schist of the Keewatin are found to occur sometimes minutely interlaminated;. at other times the jasper is in irregular 

layers; which never have any great extent and always finally pinch
VANHIHB.] LAKE SUPERIOR REGION. 133

out; at other times it is in oval forms, the greater lengths being parallel with the schistose structure. Again, the jaspilite is in great fragments within the green or massive diabasic schists, the masses having 

sometimes such relations with each other as to show that they .are a 

broken continuous layer. The branches from the large bodies of jaspilite are supposed to be caused by the crumpling, breaking, and squeezing of the entire rock structure by which the thinner sheets have been 

buckled out and thrust laterally among the inclosing schists. The ore 

always occurs associated with the jaspilite, the forms of the deposits 

being exceedingly irregular. The ore and jasper are regarded as a direct chemical deep-sea precipitate, accompanied and interrupted by reported ejections ot basic volcanic rocks from which the iron for the ore 

is extracted.

The rocks of the Aiiimikie equivalent to the Huronian and included 

in the Taconic consist chiefly of carbonaceous and argillaceous slates 

with siliceous slates, fine-grained quartzites, and gray limestones. At 

the bottom of the series is a fragmental quartz sandstone 300 feet in 

thickness, which is named the Pewabic quartzite. The slates, conglomerates, and quartzites are profoundly affected and intermingled with 

eruptive material which is similar to that found so abundantly in the 

Keewatin. These beds have the appearance of consolidated beds of 

basic lava or of porous tuff, but where this prevails there is a sensible 

gradation from the dark trap-looking beds to thin beds of slate. At 

Ogishki lake there is a slate conglomerate similar to that on the north 

shore of lake Huron. This .conglomerate is not the same as the agglomerates of the Keewatin such as that on Stuntz island, at Vermilion 

lake and Ely. The Keewatin is always nearly vertical while the dip 

of the Tacouic rarely exceeds 15°. The iron-ore beds of the Taconic 

are the quartzose, hornblendic, magnetitic group of the Pewabic quartzite; an impure jaspilite, hematite, and limonite group5 a carbonated 

iron group; and a gabbro titanic iron group. The jaspilitic hematite 

group has the same lithological peculiarities as the jaspilite beds of 

the Vermilion range. The gabbro in which the titanic iron occurs constitutes the Mesabi range. This has been before regarded as the base 

of the Keweenawan, into which it fades upwardly, but it has been 

found that this great gabbro flow was outpoured at an earlier date, 

and it is placed at or near the bottom of the Animikie.

WINCHELL (II. V.)139, in 1891, states that the syenite of Saganaga 

lake is conglomeratic in places and contains pebbles which are similar 

to each other, being mostly composed of lamellar augite, with or without grains of feldspar, but there are no pebbles of syenite or jasper such 

as occur in the Keewatin conglomerates. In the Saganaga granite, at 

the end of the portage on Granite river, is a band of silica 1£ inches in 

diameter and -3 feet in length. North of Saganaga lake the syenite 

grades into chloritic syenite-gneiss, and this into thick bedded to massive Keewatin rocks. From these facts it is concluded that the syenite 

is simply a result of locally intense metamorphism.
134 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BOLT, 86.

SECTION VI. WORK OF THE LATER UNITED STATES GEOLOGISTS

AND ASSOCIATES.

HAYDEN, 190 in 1867, in his sketch of the geology of northeastern 

Dakota, describes quartzites along the James river, Vermilion river, 

and at Sioux falls. These quartzites are sometimes conglomeratic. On 

the James river the lines of stratification are nearly obliterated, but the 

rock appears to be metamorphic. The pipestone bed on Pipestone creek 

is associated with the quartzites already mentioned and this rock is 

undoubtedly of the same age. At Sioux falls, while no well defined 

fossils were discovered, upon the outer surfaces of the rocks are rounded 

outlines of what appear to be organic remains, but the peculiar character of the quartzite points toward the Azoic series. The formation is 

tentatively referred to the Super-Carboniferous, Triassic, or downward 

extension of the Cretaceous; but Hall's opinion that this rock is Huronian is entitled to great weight.

IRVING,191 in 1883, gives a systematic account of the Copper-bearing 

rocks of lake Superior. From this group is excluded the so-called lower 

group of Logan, the Animikie group of Hunt, and also the horizontal 

sandstones known as the Eastern and Western sandstones; although it 

includes the dolomitic sandstones, with accompanying crystalline rocks 

between Black and Thunder bays, and occupies the valley of the Black 

Sturgeon and Nipigon rivers, as well as lake Nipigon. The Keweenaw 

or Copper-bearing series then includes the succession of interbedded 

traps, amygdaloids, felsitic porphyries, porphyry-conglomerates, and 

sandstones, and the conformable overlying sandstone typically developed in the region of Keweenaw point and Portage lake. These rocks 

have their most widespread extent about the west half of lake Superior, 

but also occur in the eastern part of the lake. The entire geographical 

extent in the immediate basin of lake Superior is about 41,000 square 

miles.

The eruptive rocks include basic, intermediate, and acid kinds, but 

there is no such chronological relations between these three kinds as is 

found to be the rule in Tertiary and post-Tertiary times. In the Pali- 

; sades of the Minnesota coast quartz-porphyries are found both overlain and underlain by basic rocks with abundant evidence that the 

porphyry is a surface flow. The same phenomena are seen at other 

places. Acid flows are superimposed upon basic flows, flows of intermediate acidity immediately overlie acid flows, flows of intermediate 

: acidity overlie porphyritic conglomerates, flows of intermediate acidity 

: are superimposed upon basic flows, basic rocks are intersected by 

:acid rocks, basic flows overlie acid rocks, basic flows overlie those 

of intermediate acidity, acid rocks are intersected by basic rocks. 

'There is a complete absence from the series of anything like volcanic 

: ash. The detrital rocks of the series are composed of fragments broken 

for the most part from the acid rocks of the series that is, such mate-
VANHISE.] LAKE SUPERIOR REGION. 135

rial as porphyry, both non-quartziferous and quartzifer.ous, felsite, 

augite-syenite, granitell and granite, but there are also often ionnd 

pebbles of the basic rocks, and in. some cases particles of gneiss and 

granite from the underlying series. This is thought to be due to the 

fact that such viscous material would solidify into more or less bulky 

erect masses of relatively small area, and thus be most favorably situated for degradation. Between the several kinds of original rocks there 

are no sharp lines, but a continuous series of kinds from the most basic 

to the most acid.

The lithology of the different members of the series is given in detail. 

The basic original rocks include granular, porphyritic, and glassy kinds, 

the most abundant of which are gabbro, diabase, rnelaphyre, and porphyrite. The acid original rocks include quartzless porphyry, quartziferous porphyry, and felsite, au'gite-syenite, granite-porphyry, arid 

granite. Here is included the so-called "jaspers," which have been regarded by many as metamorphosed sedimentary rocks. The basic crystalline rocks make up the greater part of the thickness of the. series, 

the beds varying from a few feet to several hundred feet in thickness. 

Each of these beds often has a twofold division, an upper amygdaloidal 

portion, and a lower compact portion, which, however, grade into each 

other. The amygdaloids not infrequently resemble beds of sedimentary 

origin, but they never show any trace of fragmental character, and 

the stratiform condition is seen to be due to a succession of thin flows 

and two fluidal structures. Laterally the beds are not of indefinite ex. 

tent, and are far less extensive than sedimentary beds of the same 

thickness. It is generally, however, difficult to prove the continuity 

or noncontinuity of a single flow over a great distance, but on the Minnesota shore individual layers were traced with certainty for 10 or 15 

miles, while other beds almost certainly have an extent of nearly 30 

miles, while groups of layers of allied characters are recognizable over 

much longer stretches. The more massive, thicker beds generally occur 

in the lower part of the series. Numerous dikes cut the basic rocks. 

These are generally small, commonly not more than 10 feet in width, 

but in the immediately underlying series on the north shore, the Lower 

Copper-bearing or Aniniikie group, are dikes of great magnitude. Of 

the original acid rocks true granite has been observed only in the Bad 

river region of Wisconsin intersecting the coarse gabbro at the base of 

the series. Quartz-porphyry and allied acid rocks have a widespread 

occurrence, two of the largest masses being the palisades of Minnesota 

and the core of the Porcupine mountains of Michigan. The detrital 

members have often a great extent. The outer conglomerate of Keweenaw point, for instance, is traced from the eastern extremity of the 

point to the Bad river in Wisconsin, a distance of at least 170 miles, 

although its thickness in this distance varies from less than 100 to as 

much as 4,000 feet. Thinner conglomerates have been traced for as 

great a distance as 50 miles.
136 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL.86.

The Keweenaw series is strati graphically separated into two grand 

divisions, an upper member, made wholly of detrital material, for the 

most part red sandstones and shale; and a lower division, made chiefly 

of a succession of flows of basic rocks, but including layers of conglomerate and sandstone nearly to the base, and also original acid rocks. 

The line of separation between the two divisions is somewhat arbitrary, 

for the sandstone gradually increases in quantity upward, but above 

the highest known eruptive member is a maximum thickness of 15,000 

feet of detrital material. The chief characteristics of the lower division 

are, first, that coarse grained basic rocks in very heavy beds are much 

more common at lower horizons; second, amygdaloidal texture is more 

frequent and highly developed at high horizons, this being more characteristic of the thinner beds; third, the gabbros are more often found at 

lower horizons while the ordinary diabases and melaphyres affect higher 

horizons; fourth, the acid rocks are found especially in low horizons, 

rarely reaching above the middle of the lower division; and,-fifth, the 

detrital beds, although seen all the way to the base, are rare in the 

lower third of the series and increase in thickness and frequency toward 

the top. The thickness of the lower division is placed in round numbers at 25,000 to 30,000 feet, while at the Montreal river its apparent 

thickness is 33,000 to 35,000 feet, but a part of this may be due to the 

westward continuation of the Keweenaw fault.

.Detailed descriptions are given of the rocks of Keweenaw point, of 

the region between Portage lake and the Ontonagon river, of the South 

range, of the region between the Ontonagon river and Kumakagon lake, 

including the Porcupine mountains, of northwestern Wisconsin and the 

adjoining part of Minnesota, of the Minnesota coast, of isle Boyale and 

Nipigon bay, of Michipicoten island and the east coast of lake Superior. 

Silver mountain, belonging to the South range, is composed of diabase,

dipping at an angle of 30°, and appears to be surrounded by horizontal 

sandstone. On the west branch of the Ontonagon are found cliffs of 

horizontal sandstone almost in proximity with ferruginous slate supposed 

to belong to the Huronian, and but a short distance from diabases regarded as Keweenawan. The isolated position of the South range is 

regarded as due to a fault, as there is no evidence whatever of a fold, 

and to regard this part of the series as a continuous conformable 

succession with the Keweenawan rocks to the north would give the 

series an incredible thickness. The Porcupine mountains are found 

to be due to a subordinate fold in the series, the core being a quartzporphyry.

All the known facts with reference to the relations of the horizontal 

sandstone to the Copper-bearing rocks of northwestern Wisconsin and 

the adjoining part of Minnesota are recapitulated. The unconformity 

between the fossiliferous Cambrian of the St. Croix valley and the 

bedded melaphyre and aniygdaloids described by Sweet, Strong, and 

Chamberlin is indisputable, and the latter rocks are identical in nature
LAKE SUPERIOR REGION. 137

and in structure with the similar rocks of Keweenaw poiut and have 

been shown to be in actual continuity with them. At Snake and Ket: 

tie rivers the diabase and diabase-amygdaloids with interbedded porphyry conglomerates are in all respects like those of Keweenaw point, 

and here, as shown by Chamberlin and McKinlay, the horizontal Cambrian sandstone overlies these beds unconformably. Sweet's examination of the Kettle and St. Oroix rivers shows that here are cupriferous 

rocks which are identical with those of Keweenaw point, upon which 

the red sandstone of lake Superior west of the Montreal reposes unconformably, at Black river, Copper creek, Aminicon river, and Middle 

river. The disturbances of the overlying sandstone described by Sweet 

are due in part to the irregularities of an unconforniable contact and to 

the pressure of the deep-seated Keweenaw rocks against the more 

shallow sandstone, but also in large measure to a faulting that has

taken place along the contact line. The phenomena if not explained as 

above may be regarded as due to the intrusion of disturbing masses or 

dikes, as suggested by Whittlesey and Norwood, or the sandstone may 

be supposed to belong to the upper division of the Keweenaw series let 

down by a great fault. The first of these suppositions is forbidden by 

the bedded structure of the rocks, and the second is shown by the general structural features of lake Superior to be a physical impossibility.

The amygdaloidal and porphyritic rocks, and the granite, granitic 

porphyry, and felsite of the Duluth gabbros and the Minnesota coast 

are found in every case to be original .eruptive rocks having all the 

evidences in their structure of this origin and none whatever of being 

metamorphosed shales and sandstones resulting from the red sandstones of Fond du Lac, as supposed by Prof. K. H. Winchell.

It is concluded that the Eastern sandstone along the south face of 

Keweenaw range is both a fault cliff and a shore cliff against which the 

newer sandstone was laid down, but not until after a large erosion, and 

that faulting again took place during or after the deposition of the 

sandstone; that this original faulting is demanded along this line by 

the relations of the Keweenaw and South ranges, without Avhich the 

Keweenaw rocks would have an enormous thickness.

The relations of the Eastern sandstone and Keweenawan traps are 

described at Bete Grise bay, along the Hungarian river and Douglass 

Houghton ravine, and sections given showing the sandstone to rest 

unconformably upon the eruptives. At the Torch lake quarry the 

Eastern sandstone is found horizontally disposed in heavy layers, containing no fragments of porphyry such as are distinctive of the Keweenawan sandstones. No evidence of a northwesterly dip described by 

Wads worth was here found. The sandstone adjacent to the trap is of 

the ordinary quartzose character. It is remarked that Wadsworth's 

statement that the feldspathic constituents have been leached from it, 

thus accounting for its differences from the Keweenawan sandstone, is 

a pure supposition. Farther west on and near the Ontona.gon river, as
138 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL.80.

at B6te Grise bay, the sandstone dips away from the north-dipping 

Keweenawan diabases at quite a high angle near the contact, which 

rapidly flattens as it is receded from. Finally along the north face of 

the South range eastward from lake Agogebic the sandstone is not 

infrequently met in a flat-lying position, and at one place lies directly 

across the course of the Keweenawan belt.

As to the age of the Eastern sandstone, it is regarded as demonstrated that it is older than the Trentonj hence its Triassic age is not 

discussed. The Western sandstone is regarded as the equivalent of the 

Eastern sandstone, although they are not found connected, nor is the 

Western sandstone at any point connected with the Mississippi valley 

Cambrian sandstone. It has, however/, already been shown that the 

Keweenawan rocks rest unconformably under the Cambrian sandstone 

of the Mississippi valley in western Wisconsin.

The Animikie series in the Thunder bay district is of great thickness, 

probably upward of 10,000 feet, comprising qnartzites, quartz-slates, 

clay-slates, magnetitic quartzites, sandstones, thin limestone beds, and 

beds of cherty and jaspery material. With these are associated in 

great volume both in interbedded and intersecting masses coarse gabbro and fine grained diabase, like those well known in the Keweenaw 

series. A broad examination of the region shows that there is little 

ground for the belief in one crowning overflow. The Animikie series is 

lithologically like the Penokee range in Wisconsin5 both series bear the 

same relations to the newer Keweenawan rocks and the older gneisses, 

and the two groups are regarded as the same.

The Animikie rocks are also the equivalent of if not actually continuous with the Mesabi iron range running to Pokegama Falls and the 

slates of the St. Louis river, although these latter are affected by slaty 

cleavage.

The Original Huronian of Logan is compared with the Animikie 

slates of Thunder bay and the two are regarded as equivalent. The 

Marquette and the Menominee Huronian, with minor exceptions due 

perhaps to metasoinatic changes, are lithologically like the Animikie 

and Penokee series, and are also regarded as belonging to the same 

horizon. The Original Huronian, the Animikie slates, the Penokee 

iron rocks, and iron-bearing rocks of Marquette and Menominee appear 

then to belong together and may hence properly be called Huronian. 

The Huronian schists in each of these areas are limited by granite and 

gneiss. There are, however, considerable areas of crystalline schists 

the relations of which are doubtful, and it is suspected that in several 

of the iron regions there are two distinct kinds of schists, those belonging to the Huronian and a schistose greenish phase belonging with an 

older series. It is also possible that a portion of the granites are eruptive and relatively new, while others, and especially those connected 

with the gneisses, may be of some sort of metamorphic origin not understood. The iron-bearing schists of Vermilion lake are, however, so
VANHISK.] LAKE SUPERIOR REGION. 139

j

like the Huronian that they are regarded as a folded continuation of the 

Aniinikie beds.

That the Aniraikie Huronian is beneath the Keweenawan rocks is 

shown by the fact that the Keweenawan beds along the Minnesota 

coast arepassed in descending order until the Animikie slates are reached 

at Grand portage bay, but there is not a direct downward continuation 

of the Keweenawan into the Animikie, for between the two there has 

been an intervening period of erosion. This is shown by the fact that 

at Grand portage bay where the two formations coine together the underlying slate? suddenly rise entirely across the horizon of 600 or 700 

feet of the Keweenawan sandstone. Also in northeastern Minnesota 

and in the Penokee district the overlying Keweenawan now is in contact with one member of the underlying series and now. with another. 

Further, in the Keweenawan sandstones of Thunder bay are found chert 

and jasper pebbles from the Animikie, while in the Wisconsin Keweenawan are quartzite pebbles apparently from the underlying Huronian. 

More abundant than these, in the Keweenawan conglomerates are pebbles of older gneiss and granite. Lithologically the Keweenawan rocks 

are also unlike the Huronian. The bedded and sedimentary series of 

the two groups are in strong contrast. The shales and sandstones of 

the Keweenawan have nothing in common with the quartz-slates and 

quartz-schists of the Huronian. Also in the Huronian there is nothing 

like the acid eruptives of the Keweenawan. They have the common 

feature only of basic eruptive rocks, and of these in the Huronian there 

are no amygdaloiclal or vesicular layers. A further difference between 

the Huronian and Keweenawan is in the degree of metamorphism. 

The Keweenawan sediments are unaltered, while the Huronian sediments are metamorphic. .Whether this metamorphism took place before 

or during the period of Keweenawan eruptions and deposition is uncertain.

That the closely plicated Huronian rocks were folded before Keweenawan time is indicated by the fact that the troughs of Huronian schists 

adjacent to lake Mpigon lie directly athwart the flat-lying Keweenawau 

beds. - If these schists are truly Hurouiau and equivalent to the unfolded rocks, as supposed by Bell, there can be no doubt of the existence of a genuine unconformity between the two systems. The Keweenawan synclinal forming the bed of lake Superior is found to comprise the whole basin, as well as a considerable area in northern Wisconsin and Minnesota. Not only the form of the lake as a whole, but 

its chief bays are due to subordinate folding or faulting of the Keweenawan series. In the great synclinal movement the underlying Huronian has partaken.

CHAMBEKUN, 192 in 1883, gives a summary of the arguments for regarding the copper-bearing series of lake Superior as pre-Potsdam: 

(1) The weakest argument of all, the general stratigraphical relations, 

indicate this. The Potsdam sandstone throughout the entire basin of
140 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [Buu,86.

o

lake Superior is always horizontal, or nearly so, while the Keweenawan 

series at many points immediately adjacent have suffered extensive disturbance. (2) The difference in thickness is enormous; the Potsdam 

rarely reaches 1,000 feet thick, while the Keweenawan series has, in 

addition to. a vast thickness of interstratified eruptives and detrital 

rocks, an upper portion free from igneous matter 15,000 feet in thickness. (3) The sandstones of. the Keweenawan series are largely composed of silicates, while the Potsdam sandstone is mainly quartzose. 

(4) At numerous points the Potsdam is found to rest against or upon 

the upturned edges of the Keweenawan series unconformably. Strong 

has found fifty-five places on the St. Oroix where the unconformable 

contact occurs. In Douglas county are four sections in which the Potsdam sandstones become conglomeratic, bearing material from the Copper-bearing series, but here the contacts are complicated by subsequent 

disturbances. There are several other districts, such as the upper St. 

Croix river, the Snake and Kettle fivers in Minnesota, and the vicinity 

of lake Agogebic in Michigan, where the quartzose Potsdam sandstone 

is in a horizontal position and lying near the upturned igneous and 

detrital rocks of the Keweenaw series. (5) The foregoing facts are all 

consistent with each other. (6) The view is dynamically simple, whereas 

any other explanation implies an extraordinary amount of local faulting 

and disturbance. (7) In the Grand canyon of the Colorado is a series 

of rocks remarkably similar to the Keweenawan, which lie directly and 

unconformably below the Cambrian.

IRVING- and VAN HiSE,193 in 1884, describe quartzites of many localities belonging to the rock series referred to the Hurom'an in the Northwest, and find that their supposed nietainorphism is due to the deposition of interstitial silica, which has for the most part coordinated itself 

with the original grains, the forms of the latter being as perfect as at 

the time of deposition. The list of rocks given include those from the 

Original Huroniau, from the various iron-bearing regions of Michigan 

and Wisconsin, from the Baraboo and Chippewa quartzites, from the 

Minnesota, Iowa, and Dakota quartzites, and from other localities.

IKVING- and CHAMBERLIN, 19' in 1885, give a systematic account of 

the junction between the Eastern sandstone and Keweeiiaw series on 

Keweenaw point. Detailed descriptions are given of the relations of 

the two series at Bete Grise bay, at the Wall ravine, at the St. Louis 

ravine, at the Douglass Hough ton ravine, at Torch lake quarry, at Hungarian ravine, and at other points. The conclusions, and the grounds 

upon which they are based, of Jackson, Foster and Whitney, Agassiz 

Kominger, Credner, and those who have followed them, are discussed 

in detail.

At Bete Grise bay the horizontal sandstone is found upon approaching the melaphyre to become tilted upward, and along the junction is 

found the evidence of faulting, both in the fluccan of the sandstone and 

in the broken character of the inelaphyre at the contact. At the
VANHISE.] LAKE SUPERIOR REGION. 141

Wall ravine the sandstone and conglomerate bearing fragments of the 

porphyry-conglomerate, with which rock the contact here occurs, are 

found to dip at a considerable angle away from the eruptive rock and 

to rest directly upon it. At the St. Louis ravine the sandstone is found 

upon approaching the Keweenaw series to become rapidly tilted upward, and before reaching the Keweenawan rocks to become vertical, 

while the interstratified eruptives and detrital rocks of the Keweenaw 

series dip away from the sandstone. At'the Douglass Hough ton ravine the horizontal sandstone is found upon approaching the Keweenaw 

series to become bent into a series of folds and to dip downward under 

the traps and porphyries, which dip at a steeper angle in the same direction. Along the contact the trap is shattered. At Torch lake 

quarry the sandstone is found to be in a horizontal position, there being 

no evidence whatever found that this structure is jointing or that the 

real dip has an inclination, as described by Wadsworth. The crystal 

outlined grains of sand here contained are found to be produced by 

secondary growth rather than crystals derived from quartz-porphyry. 

At the Hungarian ravine the relations are much the same as those at 

the Douglass Houghton ravine, except that the Keweenawan diabase is 

interstratified with conglomerate instead of quartz-porphyry. Along 

the contact the sandstone is broken.

In getting at an explanation of the facts there must be taken into 

account the bedded nature of the Keweeuaw series; the uniformity and 

steadiness of dip; the enormous thickness of the Keneenaw series; the 

general horizontality of the Eastern sandstone; thequartzosecharacter 

of the Potsdam sands in distinction to the silicate nature of the Keweenawan sands; the mutual relations and distribution of the two series; 

the relations to topography; the relations of the two series to drainage; the comparative straightness but gentle undulations of the junction line throughout its course of nearly 100 miles; the coincidence 

of the line of escarpment with the line of junction of the two series; 

the disturbance along the line of contact; the special character of the' 

distortions; the character of the junction; the junction debris; the irregular and broken contact faces of the two series; the fact that the contact occurs between the Eastern sandstone and different members of 

the Keweenaw series; the discordance of strike; the derivation of the 

pebbles of the Eastern sandstone from the Keweenaw series; the distribution of the pebbles, those of the Keweenaw series being found 

only near the immediate junction; the imperfect assortment of the 

pebbles -and matrix near the junction; the angularity of the pebbles at 

this place; the absence of large fallen masses of trap in the Eastern 

sandstone; and the proximity and relations of the Trenton limestone, 

resting as it does upon th'e Eastern sandstone within a short distance. 

These specifications are taken to point with distinctness to the conclusion that the Keweenaw series is much older than the Eastern Potsdam 

sandstone, that it was upturned, faulted along the escarpment and
142 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

much eroded before the deposition of the Eastern sandstone, that the 

latter was laid down unconforinably against and upon the former, and 

that subsequent minor faulting along the old line ensued, disturbing 

the contact edge of the sandstone.

IRVING,195 in 1885, discusses the divisibility of the Archean in the 

Northwest. The relations of the Penokee-Gogebic series to the overlying Keweenawan and to the underlying complex are first discussed. 

The area south of the Penokee-Gogebic series is found to consist of crystalline hornblendic, chloritic and micaceous schists which locally show 

unmistakable evidence of fragmental origin, but which as a whole are 

intensely metamorphosed. The granites, however, are considered as of 

eruptive origin as they intersect intricately the associated schists at 

their contacts with them, but the granite is never found to cut the 

overlying slates. Above this granite-gneiss-schist area is, first, a belt 

of slate 500 feet thick, over this a belt of iron-bearing rocks of various 

kinds, and above this quartzites and slates, all having a dip to the 

north-and extending for many miles east and west. None of these rocks 

are inetamorphic.

North of this succession of layers, the Penokee series, is the Keweenawan series, which appears at first to be conformable, but a closer inspection shows that it is now in contact with one member of the underlying series and now with another, even lying against the lowest 

member of the Penokee series. These relations are taken to imply that 

between the Keweenawan and Penokee series there was a long period of 

erosion. There is also an unconformity between the granite-gneiss-schist 

complex and the Penokee-Gogebic series. This is shown in the manner in which the regularly succeeding belts of the iron series traverse 

the courses of the lower; in the strong contrast between the two series 

in degree of crystallization, the lower series being nearly completely 

crystalline while the higher is little altered; in the highly folded and 

contorted condition of the lower series as contrasted with the unfolded 

condition of the higher; in the contrast between the contacts of the 

granite with the lower schists and with the higher slates, the former 

being invaded by it in an intricate manner, the latter never; in the 

discordant lamination of the two sets of rocks when in contact or close 

proximity; in the occurrence in the upper series, not only at horizons 

above the base, but also at points on the contact line, of abundant 

detrital material from the lower series.

In the Marquette district is found a slaty iron-bearing series which 

by common consent is regarded as the equivalent of the PenokeeGogebic series; but the two have one point of contrast, the Marquette 

is highly folded. Here intervenes between the iron-bearing slates and 

the granites and gneisses a set of greenish hornblendic rocks, called 

by Eomiuger adioritic group, which at their contact with the bounding 

granite are penetrated by them in the most intricate manner, so that one. 

can not resist the conclusion that the granite is the more recently formed
VASHISB-] LAKE SUPEEIOE REGION. 143

rock. These green schists are regarded as the equivalent of those cut 

by granite in the Penokee-Gogebic district. On this view the slate 

series of the Marquette district, consisting in the main of little altered 

rocks, was built up on a basement composed of granite and gneiss 

and greenish schist, and subsequently pushed into trough-like forms. 

In support of this view is cited the failure of 'the granite to penetrate 

the slates and quartzites associated with the iron, and the occurrence 

in the higher series of fragments from the lower, recoinposed rocks 

occurring at points where the quartzites come in contact with the 

basement rocks.

The Archean in these regions is then divisible unless the upper series 

are called Cambrian, for which there is no ground until in them fossils 

have been discovered. These upper series are compared with the Huronian of lake Huron, and are found to be lithologically like them, and 

to bear the same relations to the underlying rocks, and to them the 

term Huronian is'applied, while the underlying complex is regarded as 

Laurentian.

IBVING- 196, in 1885, gives a preliminary account of an investigation of 

the Archean formations of the Northwestern States. The problems to 

be solved are discussed. An examination pf the Original Huronian area 

of Murray and Logan shows that it is a series of rocks which is bent 

into gentle folds and which is composed for the .most part, excluding 

eruptive material, of quartzites and graywackes, with a subordinate 

proportion of limestone and chert. The rocks as a whole are very little 

altered and resemble more the fossiliferous formations than the crystaliine schists.

The Marquette and Menoininee iron-bearing series are highly folded 

and the metasomatic changes which the crystalline members of the 

series have undergone are often extreme. Excluding the greenish 

schists of the lower part of the series, which may belong to an older 

formation, the rocks are mainly fragmental slates and quartzites, including a large proportion of basic eruptives, and also iron ores, limestones, etc., the whole having a distinctly Huronian aspect. The various greenstone layers of Brooks' scheme are regarded as eruptive, either 

contemporaneous or subsequent, as are also many of the greenish schists 

whiclrby gradation pass into the massive gfeenstones. The iron ore 

a,nd jasper are regarded as of sedimentary origin, being remarkably 

like similar material in the Penokee-Gogebic and Vermilion formations 

where there can be no doubt of their water-deposited character. In the 

Marquette district, as well as in the Vermilion lake district in Minnesota, are conglomerates overlying the iron belt which sometimes contain fragments of the underlying formation several feet in length. 

These fragments prove the existence of the thejaspery and chalcedonic 

material in its present condition before the formation of the overlying 

quartzite.

The Penokee-Gogebic iron belt is regarded as continuous with the
144 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. (BULL. 86.

Hnronian of the Marquette district. The slate belt of the St. Louis and 

Mississippi fivers is undoubtedly the equivalent of the Animikie serif a 

and of the Huronian. Equivalent with those are also-the quartzitestct, 

Ghippewa and Barron counties, the ferruginous schists of the BL-.bly 

Biver, the Baraboo qua.\czites, and the quartzite series of sonth«nce 

Minnesota and southear " >rn Dakota. heir

At J$ew TJlm and Begone in Minnesota the quartzites and congi^ed 

erates plainly uncomformably overlie the gneiss. The thickness of this. 

formation here exposed is probably about 5,000 or 6,000 feet, a continuous section being found by Merriam at Sioux Falls, South -Dakota, 

having a thickness of not less than 3,000 to 4,000 feet. The tilted position of these quartzites, their great thickness, their lithological contrast 

with the Potsdam sandstone, make it evident that between these series 

and the overlying Potsdam sandstone is a great unconformity.

In the Animikie series isa rustrongly marked continuous horizon of 

cherty and jaspery magnetitic schists and -quartzites. The series as a 

whole is quite flat-lying, although having subordinate irregularities. 

The series having ferruginous schists north and west of lake Superior 

are regarded in part as having been once continuous with the Animikie 

series and are now-separated merely because of erosion on the crowns 

of the folds, the close folding of the Vermilion schists being produced 

concomitantly with the broad simple trough of lake Superior. In support of this position is the fact that the great conglomerate of Ogishki 

Manissi, with the alternating quartzites and slates of Knife lake, is 

strikingly like the Huronian rocks. It is also the case that in the 

vicinity of Agamok lake the Animikie quartzites appear gradually to 

take on a folded condition.

In these various Huronian areas quart/Ates, graywackes, and clay 

slates, with intermediate phases, make up the most of the clastic seriesAs has been seen, these are rocks which have been indurated by metasomatic changes, and it follows that the bulk of the rocks which form 

the Huronian do not properly fall under the head of metamorphic rocks. 

The various augitic and hornblendie greenstones, peridotites, and -felsitic porphyries are regarded as eruptives, while many of the schists are 

modified rocks of the same character. The cherty and jaspery rocks 

are supposed to be some sort of original chemical sediment, certainly 

not the result of metamorphisrn of sedimentary material. The limestones are in no essential respect different from many met with in the 

formations of later date.

IBYING,197 in 1886, discusses the origin of the ferruginous schists and 

iron ores of the lake Superior region. An examination of the Animikie, Penokee, Marquette, Menominee, and Vermilion districts reveals the 

fact that in all of them is found abundant carbonate of iron, which oftentimes grades into the other forms of the iron-bearing formation. The 

silica of the jasper, actinolite, magnetite schists, and other forms of 

the iron belt never shows any evidence of fragmental texture, so easily
VAN HISE.] LAKE SUPERIOR REGION. , 145

'iscovered in the case of the ordinary quartzites and graywackes, and

'therefore of chemical origin. Associated with the iron-bearing beds

ften a considerable quantity of carbonaceous or graphitic schists.

* concluded, (1) That the original form of the iron-bearing beds of

>ake Superior region was that of a series bf thinly bedded carbonf interstratified with carbonaceous shalv ?.yers in places, which

-<<3 more or less highly ferriferous. ^.Thaiy^y a process of silicin- 

 Nation these carbonate-bearing layers were transformed into the various 

kinds of ferruginous rocks now met with. (3) The iron tiros removed 

from the rock at the time of silicification, passed into solution in the 

percolating waters, was redeposited in various places, and thus formed 

the ore bodies and bands of pure oxide of iron. (4) That in other 

places, instead of leaching out, the iron has united with the silicifying 

waters to form the silicates now found, such as actinolite. (5) That 

some of the silicifying process went on before the folding, but some 

afterwards, and to the latter period belong probably the larger bodies 

,of crystalline ore. . <

WiLLis,19^ in 1886, describes the rock occurrences at several iron districts in northeastern Minnesota. At Pokegaina falls on the Mississippi 

are found outcrops of red quartzite, coarse grained sandstone, sometimes metamorphosed to a quartzite and irregularly interstratified with 

hard specular ore. On Prairie river is found granite, southeast of 

which are quartzites, sandstone, and ore.

At Vermilion lake the iron-bearing series has a dip of between 85° 

and 90°, the structure being regarded as an anticline, upon the north 

side of which is the Vermilion range and on the south side that of Two 

rivers. The succession from the base upward is as follows: (1) Light 

green, thinly laminated, chloritic schist. (2) Jasper of white, gray, 

brown, and bright red colors, interstratified with layers of hard blue 

specular ore, which also occurs in ore-bodies of considerable extent running across the bedding,- thickness 200 to 600 feet or more. -(3) Chloritic schist, similar to 1; original thickness probably about 150 feet. (4) 

Quartzite, dark gray, white, or black, of saccharoidal texture, containing grains of magnetite which make it a readily recognized magnetic 

formation; probable thickness 200 feet. (5) Conglomerate, consisting 

of sandstone pebbles and traces of black slate inclosed in siliceous 

chloritic schist. (6) Compact homogeneous rock, composed of quartz 

grains, chlorite, hornblende, plagioclase feldspar, and calcite. This 

rock may be an eruptive quartz-diorite, but is considered a metamorphosed sedimentary transition bed between 5 and 7. (7) Black clay 

slate, fissile and sonorous. It occupies a broad area north of Vermilion 

range. In section 28 huge masses of jasper form the crown of the arch 

and are imbedded in green schist, with which they agree in strike and 

dip. The jasper blocks are rectangular and several hundred feet long; 

the ends of the bands come out squarely to the contact with'the schist 

as to a fault.

Bull. 86 10
146 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

9 in 1887, discusses the separability of a Huronian group 

from an underlying series. The character of the Original Huronia'- 

area is again fully discussed. When two series of rocks are in conta 

one of which is crystalline in character and the other unquestiona 

of sedimentary origin, there is, presumptive evidence of a discorda 

between them, as, whatever the origin of the crystalline schists, tl 

present condition indicates the action of long-continued and deep-seal, 

processes of alteration and profound'erosion before the deposition upon 

them of the overlying detritals. In the Original Huronian area there 

is not only this distinction in its most marked form, but also the actual 

contact between this series and the Archeaii complex is found near the 

mouth of Thessalon river, the upper series having at its base a basal 

conglomerate, the fragments of which are plainly derived from the 

foliated crystalline underlying 'series. Allied "phenomena are also 

seen on the Canadian Pacific railway between Algoma mills and Sudbury. It is concluded that the Huronian has a group value because it 

is essentially noncry^stalline, because it is. truly clastic and sedimentary, and because it has an immense volume. There is reason to believe 

that the area which stretches from the north shore of lake Huron to 

the Mississippi river, including the basin of lake Superior, is one geological basin.

In the Marquette district the contradictory conclusions reached by 

older writers are regarded as due to the fact that the stratiform rocks 

themselves are made up of two entirely distinct sets; an older series 

of intensely altered and crumpled crystalline schists, in the main of 

greenish color, which are intricately invaded by the granite, and a newer, 

little altered, mainly fragmental series whose contacts with the granites 

and the schists of the older basement are such as to render an intervening structural break evident. The peculiar granitoid quartzites which 

Eominger regards as having been produced by the metamorphosed 

action of granite are plainly detrital derivatives from the granite, and 

often run into coarse bowlder conglomerates, particular occurrences of 

which are described. Here, as north of lake Huron, as proof of distinctness of the newer series, is a general litholdgical contrast between the 

two ; visible discordances ; the penetration of the lower strata of the 

lower series by granite veins which fail to penetrate the higher detrital 

rocks, but yield fragments to them; the development of true basal conglomerates at the contacts of the two series; and the fact that the 

higher detrital rocks are in contact with different members of the lower 

series. The most abundant of the upper series detrital rocks are 

quartzites, but there are also present clay-slates, shales, mica-schists, 

and various calcareous and dolomitic rocks, with jasper and ferruginous 

schists and iron ores Avhich are regarded as chemical sediments.

In passing southward from Marquette great areas underlain by the 

granites; gneisses and schists of the older formation are passed, but 

before the Menoniiuee river is reached at least four distinct belts are
VANUISB.J LAKE SUPERIOR REGION. 147

crossed occupied by the newer iron-bearing series. These belts of 

newer rocks are more closely folded than the Marquette district, but 

the relations between the newer and older series are identical with that 

district.

Passing now to the Penokee district of northern Wisconsin and 

Michigan, the iron-bearing series is highly tilted but unfolded, and the 

relations are therefore particularly plain. Here the lower of the two 

unconformities is established (1) by the fact that the iron-bearing series 

traverses lithologically distinct areas of the older or basement formation; (2) the intersection of the older schistose rocks by granite which 

never cut the higher series; (3) the occurrence in the higher series of 

basal conglomerates, fragments of which are from the underlying gneiss, 

granite, and schist; (4) the lithological contrast of the two sets of 

rocks, the lower being completely crystalline, folded and foliated, while

the upper is but little altered and regularly bedded. The upper unconformity is shown by the manner in which the flows of the Ke ween aw 

series are found in contact with all members of the iron series at different places along the contact line.

The Aniniikie series is gently tilted, and rests in palpable unconformity upon a folded series of schists, granites, and gneisses. Above it is 

the Keweenaw series, which bears the same relations to the underlying 

rocks as they do to the Penokee series.

North of the Animikie beds are schistose iron-bearing rocks, which 

extend from Vermilion lake to the vicinity of Knife and Saganaga 

lakes. These are flanked by gneisses and granites, and .on account of 

their lithological similarity to the Animikie rocks are taken to be their 

folded equivalent. While there is not here the same palpable unconformities as in the other regions discussed, it is believed that there are 

two groups of rocks, the apparent conformity being due to the intense 

folding.

There is then a graded series in the structural relations of the older 

and newer rocks from the Animikie, which lie upon the older formations with a slight inclination through the Penokee, which is unfolded, 

although deeply inclined; the typical Huronian, which is gently folded 

without schistose structure; the Marquette, which is crumpled between 

walls of older schists; the Menominee district, where the folding is so 

close that the discordances are no longer distinct; to the Vermilion 

lake district, where extreme pressure has produced a general community of inclination between the two groups of rocks. There is then 

in all these regions a great basement complex of crystalline schists, 

gneisses, and granites, above which, separated by a great structural 

hiatus, is the Huronian group,- mainly of detrital rocks, which is followed in turn, after a severe structural break, by the Keweenaw group, 

upon the eroded edges of which rest the Potsdam or Upper Cambrian 

sandstone. For the combination of clastic series above the basement 

complex and below the Potsdam sandstone the system name Agnotozoic is proposed.
148 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

InviNG-,200 in 1888, discusses the classification of the early Cambrian 

and pre-Cambrian formations, and particularly those of the northwestern states. The relations of the Baraboo quartzites to the Potsdam sandstone, the relations of the Potsdam to the Keweenaw series, 

the relations of the Animikie, Penokee, Marquette, Menominee, and 

Vermilion lake iron-bearing series to the underlying and overlying 

series are again fully discussed. The Keweenawan is held to overlie 

the Huronian everywhere by a very considerable unconformity. Evidence before given is repeated, and important additional evidence of 

the break is found in northeastern Minnesota. At the base of the Keweenawan is a great mass of gabbro, which extends from Duluth northeast to the national boundary, more than 100 miles, and at its maximum is more than 20 miles wide. This basal gabbro is now in contact 

with one member of the Animikie, and now with another, while in 

other places it is in contact with the lower crystalline schists or granite. In the Huronian are placed the Original Huronian, the iron-bearing series of Michigan and Wisconsin, the Black river falls iron-bearing 

series, theAnimikie series, the St. Louis and Mississippi slate series, the 

Vermilion lake iron-bearing series, the Baraboo quartzite series, and 

the Sioux quartzite series. Under the Huronian is the Laurentian, 

separated from it by a great unconformity. This is a series of granites, 

gneisses, hornblende-schists, mica-schists, and other green schists.

These correlations are held to be warranted both by the lithological 

ikenesses of the rocks in the different districts referred to the same 

grand division, and the lithological contrasts between the divisions, as 

well as by the fact that such unconformities as exist between the series 

must necessarily have a very wide extent. That one or two organic 

forms have been found in the rocks referred to the Huronian is not sufficient evidence for extending the term Cambrian down to cover this 

and the Keweenawan groups. In the Huronian are shales and slates 

which have abundant organic matter and important beds of ferruginous 

strata which were probably accumulated because of the existence of 

organic matter. The fossils discovered are of types which have a great 

vertical range above the Cambrian and may have as great a vertical 

range below it. That a pre-Cambrian fauna existed is evident, while it is 

probable that this fauna had affinities with the Cambrian itself. Such 

weak paleontological evidence is not sufficient reason to disregard the 

enormous thickness of the formations to be included in the Cambrian in 

case the Keweenawan and Huronian are here placed, as well as the two 

great unconformities below the Potsdam which must also be covered by 

this term. Archean is restricted to the pre-Huronian rocks. The volume of the clastic series between the Cambrian and the Archean is such 

as to demand a term of value equivalent with Paleozoic, and Agnotozoic or Eparchean is proposed as this term.

VAN HiSE,201 in 1889, finds the iron ores of the Penokee-G-ogebic 

series to be of sedimentary origin and to have been derived from an
VANHISE.I LAKE SUPERIOR REGION. 149

original cherty carbonate of iron which is yet abundantly present in 

the tipper horizons of the ore-bearing formation.

HALL202 (0. W.), in 1889, describes the distribution of the granites of 

the Northwestern states, and particularly those of Minnesota. They 

are found to be either intrusive or granitic veinstones, the latter being 

insignificant in quantity. The granites of Minnesota as to age are 

probably later than the Laurentian floor of the continent but earlier 

than the close of the Agnotozoic era. There are three or four grand 

periods of eruptive activity.

WILLIAMS,203 in 1890, as a result of an extended examination of the 

field relations and microscopical characters of the widespread greenstones, greenstone schists, and agglomerates of the Marquette and Menominee districts, concludes that they are all of eruptive origin. This 

conclusion is reached from a consideration of the field evidence, the

schistose phases being frequently traced by continuous gradations into 

massive forms j and from the microscopical evidence, these unaltered 

forms having all the characteristics of eruptive rocks. The original 

rock types were rather numerous, including gabbro, diabase, diabaseporphyry, melaphyre, diorite, diorite-porphyry, and tuifs. These rocks 

have been compressed, faulted, and crushed, as a result of which, combined with metasomatic changes, their present condition is produced. 

lEViNG,204 in 1890, discusses the field relations of the greenstones and 

greenstone schists of the Marquette and Menominee districts. A field 

study of these rocks, heretofore generally considered sedimentary, led 

to the conclusion that they are largely of eruptive origin, and the detailed study of Williams has shown this conclusively. In the Marquette 

district the line of demarcation between the schists and granites is not 

a sharp one, the granites intricately intruding the schists, often in such 

a manner as to render it certain that the granite is the later rock. Also 

the basic dikes which cut the greenstone schists are of wholly subsequent date to the schists themselves, and are equivalent in age to those 

which have intruded the overlying detrital iron bearing series. On the 

other hand, it is concluded that the greenstone schists themselves do not 

belong within the same geological period as that which holds the remainder of the stratiform rocks of the region; that is, the greenstone schists 

are placed along with the granites and gneisses to form the basement 

upon which the overlying detrital iron-bearing series was horizontally 

and unconforniably spread. This is shown by the fact that at a number 

of points the detrital beds which form the basement member of the ironbearing series proper bear numerous waterworri fragments of the granite when in contact with that rock, and, when in contact with the greenstone schists, fragments of those rocks. In some cases the basal quartzite appears to grade into the granite, but a study of this quartzite in 

the thin section shows its completely fragmental character. These contacts or basal conglomerates are described in Sees. 1,2,3,4,5, T. 47 N., 

E. 25 W., Mich.; in Sees. 21 and 22, T. 47 N., E. 26 W., Mich.; in Sec.
150 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

29, T. 48 N., B. 25 W., Mich.; in Sec. 20, T. 48 K, B. 27 W., Mich.; in 

Sec. 17, T. 48 K, E. 26 W., Mich.; in Sec. 21, T. 48 N., B. 27 W., Mich.; 

and at various points in T. 49 N., B. 28 W., Mich.

From these occurrences it does not appear possible to escape the 

conclusion that the greenstone schists, together with the granite, are 

greatly older than the detrital rocks, and before the latter were formed 

had already suffered disturbance a,nd deep denudation. This is certainly true if the underlying rocks are fragmental, and the conclusion can 

not be escaped if they are eruptive, for both the greenstone schists and 

the gneissoid granite must have received their schistosity before yielding 

the fragments; and, moreover, their character is such that it is generally believed that they must have crystallized in depth, and must 

therefore have had removed from them great masses of material before 

yielding the discovered fragments to wave action. There are evidently granitic rocks of two different ages in the Marquetfce district, 

because dikes of a iine grained reddish granite frequently cut the 

other granite. This later granite, of relatively small extent compared 

with the main masses, may have perhaps been later in time of formation than the detrital rocks themselves, as indicated by the presence of 

rare quartz-porphyry dikes and rare granitic dikes in the Felch mountain district intersecting a ferruginous schist of the iron-bearing series.

The above conclusions are further confirmed by the fact that the 

later greenstones interstratified with sedimentary layers, as shown by 

Prof. Williams, are precisely like the corresponding dikes in the greenstone schist area, which were evidently intruded subsequent to the 

production of a schistosity. Also the schistosity of the greenstone 

schists corresponds at times with the bedded structure of the iron series, 

while at other times there is no such correspondence. A similar examination of the facts in the Menominee district leads to identical

conclusions; that is, that the granite both south and north of the ironbearing series and the associated green schists and gneisses constitute a complex upon which the newer series was deposited.

IRVING- and VAN HiSE,205 in 1890 and 1892, give a detailed description of the Penokee series of Michigan and Wisconsin, of the complex 

of rocks south of this series, and discuss the relations which.the Penokee rocks bear to the underlying and overlying series, as well as to 

the Eastern sandstone.

South of the Penokee series is the Southern Complex, an area of fine 

grained green hornblende-schists and mica-schists, gneisses, and granites. There is often no proper contact between the granite, gneiss, and 

schist, but an apparent gradation through a considerable distance 

from one to the other, while the granite often also cuts the schist, 

playing the part of a later intrusive. Distant from the lines of contact 

the schists occupy considerable areas. In none of these rocks is discovered any evidence of clastic; origin. If the massive granites and 

syenites are regarded as eruptive, it must be concluded that many of
VANHI8R.1 LAKE SUPERIOR REGION. lf)l

the schists also have a like origin, because of the gradations between 

them.

The Penokee series proper is made up of three members, Quartz-Slate, 

Iron-Bearing, and Upper Slate, and these rest unconformably upon a 

Cherty Limestone member.

The Cherty Limestone below the base of the Penokee series proper 

varies in thickness from nothing to 300 feet and is not continuous. 

This member shows no evidence as a whole of mechanical origin, 

although occasionally a small amount of detrital material is found in it. 

It is regarded either as a chemical or organic sediment, and is called 

the Lower Penokee formation.

The Quartz-Slate member, resting upon the Cherty Limestone or upon 

the Southern Complex, is a continuous persistent layer of very constant 

thickness for many miles. It is for the most part in the neighborhood

of 450 feet thick, although at one locality it reached 800. feet in thickness. The rocks of which it is composed comprise felclspathic quartzslates, biotitic and chloritic quartz-slates, and vitreous quartzite, the 

latter being a persistent phase at the uppermost horizon. All these 

rocks are plainly fragmental and for the most part little altered, although 

occasionally by metasomatic changes they have become semicrystalline. 

The lowest horizon of the Quartz-Slate in the Penokee series proper 

was found at times to be a vitreous'quartzite and other times to be a conglomerate. The debris of this conglomerate is usually derived chiefly 

from the Southern Complex, but at several localities contains a large 

quantity of chert from the Cherty Limestone member, and also includes 

a considerable amount of red jasper pebbles, and occasionally contains 

pebbles of white vitreous quartzite.

The next overlying formation is the Iron-Bearing member, which is 

longitudinally coextensive with the underlying Quartz-Slate. The 

thickness of this formation is surprisingly uniform, varying for the 

most part between 800 and 1,000 feet, although at its eastern extremity 

it apparently becomes thicker. The main phases of rocks here included are slaty and cherty iron carbonates, ferruginous slates and 

cherts, and actinolitic and niagnetitic slates, none of which show any 

evidence of being of mechanical origin. The original form of the entire 

formation is taken to be an impure cherty iron carbonate, also bearing 

magnesium and calcium carbonate. From this condition the many 

phases and varieties of rocks now found are traced by minute stages. 

These transformations are mainly produced by secondary chemical 

changes. A comparison with the iron-bearing formation of the Animikie shows that it consists of the same kind of rocks, which have been 

derived from an iron carbonate in the same manner as those of the iron 

formation of the Penokee series. The iron ores are found to rest for 

the most part upon the underlying quartzite and upon a series of dikes 

which have cut the stratified layers. The ores in this position are secondary concentrations regarded as produced at the same time as the
152 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. IBULL.S&

modifications of the Iron-Bearing member and due to downward percolating water, which has removed silica and has substituted iron oxide.

The Upper Slate member follows above the Iron-Bearing member. It 

is of great and variable thickness, the maximum being over 12,000 feet, 

and it varies from this to entire disappearance, the overlying series 

coming in contact with the Iron-Bearing or lower members. The rocks 

here comprised are mica-schists and mica-slates, graywackes and graywacke-slates, clay-slates or phyllites, and quartzites and conglomerates, 

all of which are of original mechanical detrital origin. The micaschists and mica-slates are traced by imperceptible stages back to their 

original little altered or unaltered condition.

These. three members constitute the Penokee series proper. The 

Eastern area of the series is found to differ in many respects from the 

main area already described. This was the center of great contemporaneous volcanic activity, and consequently the succession includes 

large thicknesses of lava flows and volcanic tuffs, which are not paralleled by the rocks found in the western area, and as a result of this 

disturbing force the detrital succession is not so simple and regular.

With the Penokee series are found eruptives of two classes, dikes 

cutting' the formation and interbedded sheets, which are probably intrusions of the same age as the dikes. These eruptives are usually 

diabases, which are like the dikes found in the complex below the 

Penokee series, and which chemically are like the overlying Keweenaw 

series.

The Penokee series has approximately an east and west strike, is 

unfolded, and dips to the north at an angle varying usually from 60° 

to 80°. There are sharp flexures at a few points and small faults at 

only two localities.

While the strikes and dips of the Penokee series are persistent, those of

the underlying schists are variable and often are at marked discordance 

with the Penokee succession. The granites which cut the fine grained 

schists of the underlying complex are never seen to intersect the limestone or quartz-slate. At quite a number of places the limestone or 

quartz-slate is found immediately adjacent to or in actual contact with 

the underlying complex, when it is always found to bear numerous 

water-worn fragments from the Southern Complex, the condition of which 

is that of the rock from which it is derived. When the contact is with 

the green schists the schistose structure of the underlying rocks abuts 

against the strike of the quartz-slate, while the fragments, with their 

greater length parallel to the schistose structure, are found with their 

longer diameters in the direction of the bedding of the slate, showingthat their schistosity was produced before they were broken from their 

original position. It is then concluded that the Southern Complex is 

separated from the Penokee series by a great unconformity, and that as 

the quartz-slate is persistent for a distance of many miles, that the 

underlying complex had nearly reached a base level before the overlying series was deposited.
VALISE.] LAKE SUPERIOR REGION. 153

Above, the Penokee series are the Keweenawau rocks, which are found 

at Tyler's fork above a thickness of at least 13,000 feet of sediments 

belonging to the .Penokee series. In passing east or west from this 

point the Keweenawan rocks come in contact with lower and lower 

horizons of the Penokee series. At one place the entire succession 

appears to be cut off by it. This is taken to imply that between the 

deposition of the Penokee series and the outflows of Keweenawan time 

there lapsed a sufficient time for erosion to remove at least this thickness of sediments, and consequently that between the Keweenawan 

and Penokee series is a very considerable unconformity.

This unconformity is not, however, evident in single cross-sections. The bedded Keweenawan traps have a high inclination which 

is not markedly different from that of the Penokee succession. The 

inclination of this bedding is ascertained by the contacts of the different flows, by the inclination of their amygdaloidal horizons, and, north 

of Bessemer, by the contact between the traps and an interleaved sandstone.

At lake Gogebic the Eastern sandstone is found in a horizontal position to rest against the upturned edges of the Southern Complex and 

Penokee series alike, and to contain numerous characteristic fragments 

which can have been derived only from these series. Also very numerous fragments are found equally characteristic of the Keweenaw series, 

and it is therefore concluded that after the deposition of the Penokee 

and Keweenawan series, before the Eastern sandstone was laid down, 

that the two former were upturned and suffered great denudation.

A comparison of the Penokee series proper and the Animikie series 

shows that they are made up of like succession of rocks, occupying the 

same relative positions with reference to overlying and underlying rocks, 

one dipping northward under the basin of lake Superior and the other 

dipping southward under the same body of water. They are therefore 

regarded as equivalent. As probably equivalent with the Penokee 

series are also placed the various areas of rocks in the lake Superior 

basin referred to the Upper Huronian.

A comparison of the Penokee with the Marquette succession shows 

that there is a very close correspondence. Unconformably below the 

Marquette and Penokee elastics is a crystalline basement complex. 

Within the pre-Keweenawan elastics in each district is a second physical break. Below this break, in the Penokee district, the formations 

of the lower Marquette are now represented only by the Cherty Limestone. That other members once existed is indicated by the presence of 

fragments of jasper and quartzite in the lowest horizon of the QuartzSlate. Formations composed of these rocks and a cherty limestone 

are the characteristic members of the lower Marquette.

The correspondence of the members of the Penokee series proper 

with those of the upper Marquette is complete. The upper Marquette 

and Penokee series, looked at broadly, are great slate formations, both
154 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. | BULL. 86.

of which contain, near the base, an iron-bearing horizon. In the Penokee 

series that portion of the slate overlying the ore formation has been 

called the Upper Slate member, and that below it the quartz-slate 

member. The lower part of the quartz-slate is a quartzite and conglomerate, which corresponds to the quartzite and conglomerate forming the base of the upper Marquette series. The uppermost horizon of 

the Penokee quartz-slate is a narrow layer of persistent quartzite, 

which does not appear to be represented in the Marquette district. 

The character of the ore-bearing' member is identical in both districts, 

being unquestionably derived from a lean, cherty carbonate of iron. 

The characteristic rocks of both are now the iron carbonates, ores, and 

cherts containing bands and shots of ore. The chief difference between 

the two is that in the Penokee district the actinolite-inagnetite-schists 

are more prevalent, and that the iron-bearing formation is more persistent. Connected with this fact is perhaps the presence of the upper horizon of quartzite, which shows that a clearing up of the waters occurred 

before the beginning of deposition of the iron-bearing sediments. A 

still further analogy between the Penokee and Upper Marquette series 

is the presence in both of abundant surface volcanics. We have then 

in the two districts the following parallel descending pre-Keweenawan 

succession.

PENOKKE.

Upper slate, locally mica-schist.

Iron-bearing formation.

Quartz-slate; upper horizon persistent 

quartzite; central mass a slate; lower 

part often conglomeratic, bearing fragments of lower series, and locally a

quartzite. 

Unconformity. 

Eroded away. 

Limestone. 

Unconformity. 

Basement complex.

MAUQUETTE.

Upper slate, rather exteusiArely niicaschist.

Iron-bearing formation.

Lower slate; lower part quartzite or 

quartzite-cougloinerate, bearing fragments of lower series, either lower Marquette or Archean.

Unconformity.

Iron-bearing formation.

Limestone and lower quartzite.

Unconformity.

Basement complex.

VAN HiSE,206 in 1891, describes the physical break between a Lower 

and an Upper Huronian series. In the Marquette district the Lower 

series includes the lower quartzite and novaculite of Brooks, the limestone formation as well as the chief iron-bearin g formation containing 

the hard ores, which is composed chiefly of jasper and actinolitic and 

magnetitic slates. The Upper series has at its base a vitreous quartzite, but is chiefly composed of black slates sometimes carbonaceous, 

graywackes, and mica-schists, together of great thickness, and locally 

contains belts of ferruginous cherts and slates, including ore-bodies, 

which are, however, of a different character from the ores of the Lower 

series. The area occupied by the Upper series is equal to or greater 

than that of the Lower series. That the two series are separated by
VAN Hian.1 LAKE SUPERIOR REGION. 155

a great unconformity is shown by numerous contacts. At these contacts the lower quartzite of the Upper series contains abundant 

fragments of the Lower series which had reached their present condition before being deposited in the former. Tliat the Lower series 

has been greatly folded and deeply truncated before the Upper series 

was deposited, is further shown by the much banded and contorted 

jasper abutting at all angles against the beds of the uptilted but simply folded Upper series, and also by its more crystalline character.

Since great belts of conglomerates containing abundant fragments of 

ore and jasper are found in the Upper Vermilion, at Ogishki lake, and 

in the Upper Kaministiquia series, it is argued thr,o the source of this 

material is the great belts of iron ore and jasper contained in the Lower 

Vermilion, Hunters island, and Lower Karninistiquia series. That the

Vermilion lake conglomerate is imconformably above the schists in

vertical attitude, bearing ore and jasper, is further indicated by the 

fact discovered by Merriain that on the islands of Vermilion lake 

the conglomerate is found to be in a series of gentle folds although 

having a vertical cleavage developed. Merriain regards the conglomerate as a comparatively thin formation overlying and overlapping 

the Lower series. The presence of red jasper conglomerate in the 

Original Huronian suggests that in this district-will be found in the 

future a Lower series similar to the Lower Vermilion bearing jasper 

and ore.

It is concluded that the confusion in correlation of the formations 

about lake Superior is due to the failure to recognize this general unconformity. Once recognized, the structural conclusions to which the various writers have most steadfastly held are found to be in general 

harmony. Above the physical break, and constituting the Upper 

Huronian (equivalent to the Original Hurouian) are the Anirnikie and 

Upper Karainistiquia, Upper Vermilion, Upper Marquette, Western 

Menominee, Penokee-Gogebic proper, the Dakota, Iowa, Minnesota, and 

Wisconsin quartzites surrounded by the fossiliferous series. In the 

Lower Huronian is the Keewatin (in part at least), the Lower Kaministiquia, Lower Vermilion, Lower Marquttte, Felch mountain iron-bearing 

series, Menominee proper, and the Cherty limestone at the base of the 

Penokee series, and the Black river falls iron-bearing schists.

BAYLEY, 207 in 1892, concludes, after a microscopical examination of 

the specimens obtained in the neighborhood of Akeley lake, from the 

formation designated Pewabic quartzite by the Minnesota geologists, 

that they are granulitic and quartzose phases of the gabbro, and that 

none of them are sedimentary rocks. These granulitic and quartzose 

gabbros are traced into ordinary gabbros; consequently the Pewabic 

. quartzite is a part of the gabbro. The ore beds of the Akeley lake 

series, interstratified with these granulitic gabbros, also belong with the 

overlying gabbro and not with the Animikie. This conclusion agrees 

with that of Chauvenet reached in 1883 and 1884. This iron-bearing
156 PRE-CAMBRIAN ROCKS OF NORTH AMERICA.. fBULi.80.

silicified gabbro has been traced by this geologist southwest through 

sees. 25, 35, 34, T. 65 K, E. 5 W., to Mitchigamme lake. The same 

silicified gabbro belt has been found by Merriam at lake Gobbemichigomog.

MERRiAM, 2"8 in 1888 and 1889, in a detailed systematic study of parts 

of the Marquette district, ascertained that about many of the masses 

of basic eruptives the clastic rocks bow in a quaquaversal manner, indicating that many of the diabases, gabbros and diorites are intrusive 

subsequent to the formation of the Marquette series, and that the local 

strikes and dips are often due to this cause.

VAN HiSE,209 in 1890, examined the rock succession at Iron mountain, Michigan. Overlying the ore formation of the Ludington and 

Chapininines is a conglomerate which bears fragments of ore and jasper. 

It therefore appears that after this material reached its present condition in the ore-bearing series it was eroded and furnished debris for a 

newer series.

PUMPELLY and VAN HiSE,210 in 1891 and 1892, find that in places 

the ore formation of the Menominee and Felch mountain districts passes 

down into the limestone. This gradation may be well seen in the Menominee district at a quarry east of the Ohapin mine. Also in the 

deeper workings of the Chapin, the ores resting almost directly upon 

the limestone are found to bear a considerable percentage of carbonates, 

including iron, calcium, and magnesium. The Metropolitan ore deposits 

in the Felch mountain district are found associated with or within the 

limestone. At one pit the ore and jasper may be seen interlaminated 

with and grading down into a limestone. It is therefore probable that 

the ore formation of these districts, in part at least, is but an upward 

continuation of the limestone formation, perhaps differing from it originally only in that the upper part contained a greater quantity of original carbonate of iron.

Above the ore formation at Quinnesec, test pits show the presence 

of a typical chert and jasper conglomerate, in every respect like the 

basement conglomerates of the Upper Marquette.

SECTION VII. SUMMARY OF RESULTS.

The lake Superior region is the one in America about which most 

has been written and which has furnished the most definite knowledge 

of the structural relations of the pre-Cambrian rocks. Contained in the 

foregoing summary of literature is potentially much that follows, but 

it seems desirable to put together the conclusions which may be considered as determined and see how far the various positions taken 

by the' different writers are really in harmony. Unless otherwise stated, 

the cited positions of the various authors are their later expressions; 

oftentimes earlier and different views have been held. For the sources 

from which the conclusions are drawn it will be necessary to turn to
YANHISK.I LAKE SUPERIOR REGION. 157

the literature, from which, by means of the footnotes, the material may 

be traced to the originals.

The four series to be arranged are those known as the lake Superior 

sandstone, the Keweenawau, the Huronian, and the Laurentian. The 

last two have by certain later writers been again subdivided.

LAKE SUPERIOR SANDSTON.K.

The horizontal red sandstone of lake Superior was recognized as the 

most extensive formation of the lake by the earliest geological voyageurs, and in what follows this formation will be called the lake 

Superior sandstone. The early travelers, Schoolcraft, Bigsby, and 

Bayfield, regarded it as the Old Red sandstone, although Bayfield later 

considered it to probably underlie the fossiliferous red sandstone of St. 

Marys river. It was placed by Jackson, Marcou, and for a long time 

by Bell, as the New Bed sandstone. Very early others, including- Dawson (Sir William), Foster, Houghton, Logan, Owen, Whitncy, and 

Kogers, regarded the sandstone as Lower Silurian or Potsdam. In 

1873 Komiuger finally demonstrated what Houghton had long before 

stated, that the horizontal sandstone is directly overlapped by the Calciferous formation. The sandstone was therefore placed as Potsdam, 

Avhich position it has held since that time without dispute by anyone 

acquainted with the region.

It was very early seen that the horizontal sandstone is newer than 

the granites and slates of lake Superior, which occupy a lower position 

than the Keweenawan. Schoolcraft saw, as early as 1821, the unconformity between the granite and. sandstone at Granite point, and that 

between the latter and the slates on the St. Louis river at the head of 

lake Superior. Bayfield recognized this unconformity in 1829, saying 

that the many instances of the conjunction of the sandstone and granite 

proved that the sandstone was deposited after the granite occupied its 

present position. Rogers saw the same relations between the sandstone 

and the slates of Chocolate and Carp rivers, although at first he regarded 

the latter as Primal. Owen, in 1847, described in northern Wisconsin 

like unconformable relations between the horizontal sandstone referred 

to the Potsdam and the crystalline rocks. Norwood, in 1847, again saw 

the unconformity between the lake Superior sandstone and St. Louis 

slates at Fond du Lac, described by Schoolcraft many years before. 

Foster, in 1848, saw the same unconformable relations between the 

sandstones and slates at L'Anse. Since these early discoveries of the 

relations between the sandstone and the crystalline rocks were announced they have been confirmed at these original localities and at 

numerous other localities by many observers.

As to the relations of the lake Superior sandstone with the sandstones interstratified with the trappean rocks, i.e., the Keweenawan, 

there has been the greatest diversity of opinion, and the question is one 

in which there is not yet entire unanimity, although the weight of the
158 PRE-OAMBKIAN ROCKS OF NORTH AMERICA. [nuLL.86.

evidence is so strongly in favor of the inferior position of the Keweeiiaw series that this conclusion is doubted by but few geologists.

Bayneld, Bigsby, Burt, Rogers, Schoolcraft, and Whittlesey made 

no distinction between the lake Superior and Keweenawan sandstones, 

apparently not recognizing that there was any'question of their not 

being equivalent. Jackson, followed by Bell, for many years apparently regarded the Keweenawan sandstones as later than the lake Superior sandstone. Jackson places the former as New Bed, and states 

that the sandstone of the Pictured rocks may not be of the same age. 

Bell at iirst thought the Keweeiiawau Permian or Triassic, while cognizant of the fact that the lake Superior sandstone is older than the 

Triassic, but recently this writer places the sandstone as probably unconformably above the Keweenawan. Foster, Wads worth, Whitney, 

and Winchell (N. H.), after comparisons and studies of the problem, have 

maintained that the lake Superior and Keweenawan sandstones belongto the same series. Agassiz, Brooks, Chamberlin, Dawson, Houghton, 

Irving, Logan, Macfarlane, Bell, Owen, Pumpelly, Bominger, Selwyu, 

Strong, Sweet, and Wooster have held as their latest view that the 

Keweenaw series is older than the lake Superior sandstone. Agassiz 

at first regarded all the sandstones of the same age, but came to the 

conclusion afterwards that the sandstone was deposited against the upturned Keweenaw series. Agassiz, Brooks, Chamberlin, Dawson, Irving, Owen, Pumpelly, Rominger, Strong, Sweet, and Wooster maintain 

a great unconformity between the two. Macfarlane held that there was 

a doubtful unconformity between the Keweeuaw series and the lake 

Superior sandstone, the former occupying an inferior position. Houghton's, Logan's, and Selwyn's position is that the Keweenaw series is a 

downward extension of the lake Superior red sandstone. The latter is 

regarded by Logan as probably Chazy, and the Keweeiiawau therefore

Calciferous or Potsdam. Selwyn and Bell now place the Keweenawan 

as Cambrian.

The relations of the horizontal sandstone in northern Wisconsin to 

the melaphyres and traps regarded as Keweenawan have been described by all observers to be those of unconformity, the horizontal 

sandstone resting upon the upturned edges of the Keweenaw series. 

The only point of difference has been whether this sandstone is Potsdam 

or not. It is so regarded by the Wisconsin geologists and by Owen, 

but is by N. H. Winchell called St. Croix and is placed above the Potsdam. The true position of this sandstone another will discuss, but no 

one doubts that it belongs near the base of the Northwestern Paleozoics. 

The extensive area of horizontal sandstone about Agogebic lake between the two highly tilted trap ranges was long ago cited by Brooks 

and Pumpelly as evidence that the lake Superior sandstone is far later 

in age, it being found not distant from the highly tilted Keweenawan 

eruptives.

The controversy has been most extended as to the relations of the
vAN-msiv] LAKE SUPEEIOE EEGION. 159

two series on Keweenaw point. A part of what has been regarded as 

the lake Superior sandstone, adjacent to the trap range, has been shown 

by Wadsworth to belong with the Keweenaw series, and it is even yet 

a debatable question as to just where at certain places the lake Superior 

sandstone begins and the Keweenaw series ends; because by all it is 

now agreed that nea,r this contact is an ancient fault of great magnitude, along which post-Potsdam slipping has taken place.

In considering the question whether the lake Superior sandstone is a 

part of the Keweenawan, the general field relations are more significant 

 than all else. Wherever the Keweenaw series appears in its characteristic development about lake Superior, ironi Michipicoten on the east 

to Duluth on the west, from Thunder bay on the north to Keweenaw 

point on the south, it is a titled series, the inclinations rarely being less 

than «'W°, never less on the south shore, while more commonly they are

much higher, running often to 80°. The lake Superior sandstone, on 

the other hand, wherever found, is horizontal, except along lines of contact with Keweenawan or other rocks, and here the tilting has been 

explained to be due to faulting. The only locality remote from a contact at which the sandstone is said not to be horizontal is Traverse 

island, and at this place the facts upon which the statement is based 

have not been published. The lake Superior sandstone runs as a long 

tongue for a distance of more than 50 miles, always in horizontal attitude, gradually narrowing to the west; between the north and south 

highly inclined Keweenawan trap ranges to near the Montreal river. 

Nowhere is it interlaminated with or cut by a single eruptive rock of 

any kind. The finding of detrital rocks between the lava flows of the 

South range of the Keweenawan has no bearing against this.assertion 

any more than does the existence of such rocks in the main trap range. 

Before it can be concluded that such tilted interlaminated detritals are 

a part of the horizontal Eastern sandstone the two must be traced 

together in continuous exposure.

. These broad field relations and the absence of trap point with irresistible force to the conclusion that the lake Superior sandstone is a far 

later formation, laid down, since the Keweenawan was deposited, uptilted, 

and eroded. If this is not the case, that it in broad areas should have 

wholly escaped the dynamic movements which upturned the Keweenaw 

series everywhere about lake Superior is absolutely inexplicable. 

Equally strange is the fact that it has everywhere escaped intrusive 

material. It is not a common thing for eruptive activity which extends 

over distances of 300 miles east and west and 100 miles north and south 

to continue in full force up to and stop along a ruled line 100 miles 

long. That this occurred must be believed if the lake Superior sandstone is regarded as belonging to that part of the Keweenaw series, 

interbedded with the traps, as advocated by Wadsworth. The absence 

of eruptive material in the horizontal sandstone on the theory that it is 

a part of the Keweeuawan can be explained only by regarding it as the
160 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

equivalent of the upper members of the Keweenawan, and even this 

hypothesis would leave wholly unexplained the strange field relations. 

The amount of positive evidence, based upon contact relations, necessary to establish the conclusion that the lake Superior sandstone is 

interstratified with the Keweenaw series, considering these general 

relations (mentioned by Logan as early as 1863), would need to be very 

great indeed.

However, the great mass of the evidence of contacts bears toward 

the later age of the sandstone. At the very numerous .localities in 

Wisconsin in which the contacts are not obscured by faulting, all who 

have examined the district are agreed that the sandstone there found 

does rest unconformably upon melaphyres and traps in every respect 

identical with those of the Keweenawan. Also the order of superposition of the Potsdam sandstone and the Keweenawan are shown by the 

deep well at Stillwater, Minnesota, described by Meads. This well 

passed through 700 feet of St. Croix and Potsdam sandstone and then 

went into the characteristic interbedded sandstones and eruptives of 

the Keweenaw series. This occurrence alone would seem to demonstrate the inferior position of the Keweeuawan, although from the 

nature of the case it can not determine whether there is an unconformity between the. two. The only district in which anyone has maintained that the lake Superior sandstone does pass in continuous exposure between the traps is along the southern, border of the Keweenawan of Keweenaw point, and, as already said, it is now not denied 

that there has been faulting here both before and since the deposition of the Eastern sandstone. Moreover, the fault is probably an 

overthrust. It is, then, a district in which the contacts and relations 

are particularly liable to be confusing and misleading. Even here, 

however, examinations by Agassiz, Chamberlin, Irving, Eominger and

Pumpelly, have led them all to the conclusion that the Eastern sandstone is newer than and overlies the trap, while only Foster and Whitney 

and Wadsworth maintain the contrary.

Nearly all of the positive evidence as to the relations of what is 

known to be the lake Superior sandstone to the Keweenaw series is 

that the former is far later than and was deposited upon and against the 

upturned edges of the Keweenawan; that between them is a great unconformity ; and, as has been seen, this conclusion is the one reached 

by the greater number who have studied the question critically. As 

the lake Superior Sandstone is Potsdam, it follows that the Keweenawau is pre-Potsdani: and since the unconformity separating the two 

is so great, the latter is probably pre-Cambrian.

THK CHARACTER OF THE KEWEENAW SERIES.

Of the forms of the word proposed for this series, Keweenawian, 

Keweeniau, and Keweenawan, the last is apparently preferable as being 

most directly derived from the geographical term Keweenaw.
VANHJSE.] LAKE SUPERIOR REGION.

Bayfield, in 1829, recognized the detrital character and source of the 

debris of the Keweenawan conglomerates, and concluded that they 

must be later than the traps.

The existence of a succession of interbedded elastics and volcanics 

12,000 feet thick about lake Superior was recognized by Logan as early 

as 1847, while in 1852 the same author accurately characterized the series 

as an alternation of sandstones and conglomerates, ainygdaloids- and 

traps. The work of Foster and Whitney on the south shore established 

about the same time the existence of a similar great succession on. 

Keweenaw point, although the conglomerates were by these authors 

regarded as friction conglomerates caused mainly by volcanic action 

upon the earlier sandstones. Jackson recognized that the conglomerates are of true detrital. origin. The first clear appreciation of the 

contemporaneous iiiterstratified relations between the voloanics and 

detrital rocks on the south shore was reached by Pumpelly and Marvine. 

Their work was much fuller on this series of rocks than any that had 

gone before, and as a consequence of this the rocks were recognized as 

a distinct system to which the term Keweenaw group was applied. 

Logan, on the north shore, included in his Upper Copper-bearing rocks 

what is here called Keweenawan and the 'iincomformably underlying 

Animikie. He however recognized that the two have a very different 

lithological character. The felsites, quartz-porphyries, and other acid 

rocks in the earlier reports frequently called jaspers and amygdaloids 

were by many of the earlier authors supposed to be metamorphosed 

sandstones. This position is, I believe, for the acid rocks, held by no 

writer at the present time, with perhaps one exception, and for the 

amygdaloids by none. The work of Wadsworth, Pumpelly and Irving 

has demonstrated beyond all doubt that these rocks are original eruptives. The Keweenawan is now generally recognized as a series many 

thousands of feet thick, consisting of interbedded lava flows and waterdeposited detrital material, derived chiefly from, the contemporaneous 

igneous rocks. The volcanics are predominant in the lower part of the 

series, the interstratifications of the two are most frequent in the middle 

portion, and the upper part of the series is free from volcauics.

.RELATIONS OF KEWEENAW AND UNDERLYING SERIES.

Coming now to the relations of the Keweenaw and next underlying 

series, opinion is nearly unanimous. As these two series were folded 

together to form the basin of lake Superior, the earlier writers regarded 

them as conformable. ' That they are really discordant was first recognized by Brooks and Pumpelly, who found that the base of the Keweenawan is now in contact with one formation of the underlying series 

and now Avith another, and from this general relation they argued an 

erosion interval. Brooks also brought forward as evidence of this conclusion the wholly unaltered character of the Keweenaw an detritals and 

. the simplicity of its folding as compared with the Huronian, The >\risBull. 80 11
162 PRE-CAMBRIAN. ROCKS OF NORTH AMERICA. [nu.L.86.

cousin geologists corroborated Brooks's and Pumpelly's results. When 

the relations of the series on the north shore were closely examined 

actual evidence of the erosion interval was found by Irving1 at Thunder 

bay. The same was seen by McKellar, and upon mapping the two 

series in northeastern Minnesota, Trving and Merriam found that the 

same discordance which was found on the south shore appeared, that is 

to say, the base of the Keweeuawan is now in contact with one member 

of the underlying series and now with another. Selvvyn finds at Thunder bay no evidence of this erosion interval, but this testimony is negative and stands alone. The great mass of evidence from many localities agrees that there is a physical break at the base of the Keween a wan.

The last point to consider in this connection is the reality of the existence and the position of the so-called crowning overflow of the northwest shore. This was described by Logan, Bell, Selwyn and others, 

and some were inclined to place it with the Aniinikie and others with 

the Keweenawau. Irving, in his general treatise on the copper-bearing 

rocks, does not-recognize this overflow as a general formation, but places 

the more important flows to which this term has been applied at the base 

of the Keweeuawan. Later work in northeastern Minnesota shows that 

at the base of the Keweenawau is a great area of gabbro, the thickness 

and magnitude of which, is incomparably greater than the so-called crowning overflow of Thunder bay. This great mass of gabbro extends from 

Duluth northeast to the National boundary, a distance of 100 miles or 

more, and is at its maximum outcrop more than 20 miles in width. 

There is no question, unless it be considered a subsequent intrusion, 

that this great gabbro is.the base of the Keweenawau, foritnow comes 

in contact with one member of the Aniinikie and now with another. 

At other times it is in contact with the crystalline schists of the Lower

Huronian, and again with the granite and gneiss of tlie Laureiitian,so 

that it is evident, if it is a part of the regular succession, that all of 

these rocks have been deeply eroded before its appearance. This gabbro has been, however, too little studied to venture an opinion as to 

whether it is a great surface flow or succession of flows, or, as suggested by Bayley, an immense reservoir in the nature of an early laccolite or batholite which furnished material for the subsequent diabase 

dikes and sheets of the Auirnikie and for basic surface flows of the 

Keweenawau. Eecently N. H. Winch ell, contrary to all previous work, 

places this gabbro as older than,the Aniinikie. Little evidence is given 

to support this change of view. 'No section is given illustrating the supposed structure. To the writer there appears to be great if not insuperable difficulties in the*way of the correctness of this conclusion.

(JKXKRAJ, SUCCESSION ACCORDING TO JJ1FFEUKXT WAITERS.

In taking the next step downward, we come to the complex about which 

there has been great diversity of opinion and about which it is difficult
VAN BIBB.] LAKE SUPERIOR REGION. 163

even yet to see clearly all the results which legitimately follow from the 

work done. The crude 11 otion that the sandstones, traps, j aspers, gneisses, 

granites, and all other rocks of lake Superior represent one great formation, the crystalline phases being more metamorphosed materials, as 

maintained by some of the earlier geologists, would now hardly be held 

by any one. Also it is doubtful if any would deny that the rocks below 

the Keweenaw series are divisible on a structural basis, if the Auimikie 

series is here included. The successions deduced by the geologists who 

have made the most extended study of the lake Superior region are as 

follows:

Logan makes the Keweenawan a downward extension of the lake 

Superior sandstone. Below the Keweenaw series, as before defined, 

is a set of slates (the Animikie) of very considerable thickness, which 

are, however, a part of the Upper Copper-bearing group, and therefore 

superior to the Original Huronian or Lower Copper-bearing group. The 

'Auimikie rests uuconformably upon the Huronian. As to the relations 

of the Huronian and Laurentian about lal^e Superior little is said, except that at one place they appear to be conformable and grade into 

each other. We thus have Logan's succession, lake Superior sandstone; Keweenawan; Animikie; unconformity; Huronian; Laurentian. 

The Auimikie, as well as the Keweenawan, is regarded as a part of the 

Cambrian series.

Selwyn's succession differs from Logan's only iu that he maintains 

that all of the rocks underlying the Animikie in Canada constitute one 

general conformable succession, but divisible into two systems upon 

lithological grounds and the superior position of the second. These 

are the Laurentian and Huronian. This order is also that, of Bell. 

With these authors the Laurentian is granitoid and gneissic, while 

the Huronian is quartzose, hornblendic, schistose and slaty.

Foster and Whitney's succession is Keweenawan, which includes the 

lake Superior sandstone; unconformity; Azoic the latter said to be 

indivisible except on the north shore, and the granites are intrusive 

rocks later than the Azoic slates. On the north shore the Animikie 

reposes upon the granite. Until recently Wadsworth has held to the 

same succession as Foster and Whitney. In his last paper, however, 

he states it is probable that in the Marquette Azoic there are three distinct geological formations or ages to which he applies, beginning at 

the base, the terms Cascade, Bepublic, and Holyoke formations. The 

last two are unconformable with each other.

Macfarlane recognizes a Huronian and a Laurentiau, but -regards 

both series as wholly of igneous origin and the distinction between the 

two a lithological one, the basic green schists referred to the Huronian 

being newer than the granite and gneiss, and the pseudo-conglomerates 

found in the Huronian a consequence of the intrusion of the latter, in 

which process fragments of granite and gneiss were caught. The 

Keweenawan is full of debris from the Huronian,
164 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

Brooks, Punipelly, Irviiig, Chamberlin, Sweet, and. Wright recognize 

about the same general succession; lake Superior sandstone; unconformity; Keweenawan; unconformity; then a great system of rocks 

included in the Huronian; another unconformity; and then a complex 

of granites, gneisses and schists., Irving in his later work separates 

from the Huronian and puts in the Laurentian the formation of dioritic 

schists, obscure green conglomerates, chlorftic schists, etc., cut by 

granite veins in the Marquette district, which Brooks placed as the 

lowest part of the Huronian, but the relations of which are said not to 

have been fully made out. There is the further resultant, difference 

between Brooks and Irving that Brooks regards^ very considerable 

masses of granite in the Menominee district as the highest member of 

the Huronian. As this granite is said to overlie conformably the Huronian schists and to send dikes into them, it is suggested that toward 

the end of the Hurouiau period there was a great eruptive outflow of 

granite. As has been seen, these facts are explained by Irving by 

excluding from the Huronian the granite and the schists cut, although 

it is recognized that lesser granitic intrusions have occurred since Huronian time. c

Bominger, in his earlier work on the south shore, seeing that his dioritic group of Huronian rocks is cut by granite, and considering the 

former as a sedimentary rock, and finding also, as he believed, actual 

transitions between the fragmental quartzites and granites, placed the 

whole complex as Huronian and regarded the granite as the youngest 

member. These positions are, however, very largely abandoned in his 

later unpublished work. The existence of granite and gneiss prior to 

the deposition of, and which have yielded d6bris to, the lowest members 

of the Huronian, is recognized, although contacts are said to be not 

often sufficiently frequent to enable a discrimination to be made between the original primary granites and gneisses and those of later 

eruptive origin. The recomposed character of the detrital rocks which 

repose upon, and have derived debris from the granites and gneisses, 

instead of grading into them, is now seen. It is, however, still maintained that the great mass of the granite and gneiss is an eruptive of 

later age than the detrital rocks. The dioritic group, which is so frequently cut by granite veins, before considered as the bottom of the 

Iluronian, is recognized as an igneous rock which must be excluded 

from the sedimentary series. Eominger's succession is, then, la.ke Superior sandstone; unconformity; Keweenawan; unconformity; Huronian sedimentary series, which has, however, been disturbed by great 

intrusions of granite and gneiss, with also basic rocks; unconformity; 

granite-gneiss-schist complex.

It is therefore to be noted that Brooks, Irving, and liomlnger, who 

have done the most work in the detailed mapping of the rocks of the 

south shore, reach an identical conclusion as to the succession, the only 

difference being one of emphasis. Roniinger insists on the great impor-
VASHISE.] LAKE SUPERIOR REGION. 165

ta-nce of the later granite-gneisses, but does not emphasize the presence 

of the granite-gneiss-schist complex; Irving, on the other hand, reverses 

the emphasis; while Brooks occupies an intermediate position. It is 

most significant that these three men, starting with different views, 

have finally reached like conclusions. For a long time Ron-linger denied 

the existence of the basement granite-gneiss-schist complex. Irviug 

was slow to recognize the presence of later intrusive granite. In 

Brooks's earlier work in the Marquette district he did not find the 

evidence of intrusive granite-gneiss which he found later in the Menominee district.

Lawson recognizes a physical break at the base of the Keweenawan 

and a great break at the base of the Animikie, and divides the underlying complex about the lake of the Woods and Kainy lake, Ontario, 

into Keewatin, Coutchiching, and Lanrentiau, this being the order of 

occurrence downward, but in age the granitic and gneissic rocks are 

later than and Intrusive in the schistose rocks. In this matter Lawson 

agrees with the earlier work of Bigsby upon Rainy lake and that of 

Dawsou upon the lake of the Woods, except that Dawson did not regard all of the granite-gneiss of the lake of the Woods as later igneous material. These relations are the same as those described by 

Foster and Whitney, and by Waclsworth between the granite-gneisses 

and the Azoic slates on the south shore. With Dawson, Lawson agrees 

that the Laureritian gneiss and granite and the overlying schists are 

conformable. By both of these writers the schistose rocks of the lake 

of the Woods are regarded as sedimentary and largely of volcanic origin. There is the further agreement between Lawson and Dawson on 

the north shore and Foster and Whitney, Wadsworth, Irving, and 

Williams on the south shore that they regard the greenstone slates 

as largely iathe nature of volcanic ash. Lawson gives the schistose 

rocks about Rainy lake a tAvofolcl division, both series being regarded 

as sedimentary and in apparent conformity, but there are great differences in the materials of which the series are composed as well as in 

degree of crystallization, and basal conglomerates are found at the 

bottom of the upper series. Between the two there is believed to be 

a considerable geological break. The upper is the equivalent of the 

schistose series of the lake of the Woods. To cover the two series is 

proposed the system name Ontarian. Lawson's succession is therefore 

Keweenawan, unconformity, Animikie, unconformity, Keewatin, unconformity, Coutchiching, irruptive unconformity, Laurentian ciittingboth 

Keewatin and Coutchiching.

It is of interest to note that Eoininger's early conclusions as to the 

general relations of the rock series on the south shore were almost identical with those rea,ched by Lawson as to the relations of the different 

series on the north shore; that is, the dioritic group, the lowest Huron - 

ian, is regarded as remelted metamorphosed Huronian sediments, the 

more crystalline character of the rocks being due to their closer prox-
16G PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

iinity to the volcanic forces, and while the great masses of granite-gneiss 

are below the dioritic group, these rocks are also interstratified with 

and cut the dioritic rocks, the whole granitic group being regarded as 

of igneous origin, and later in age than the sedimentaries. The likeness 

of the dioritic group and Lawson's Keewatin at once suggests itself. 

As has been seen, Bominger's later studies led him materially to modify 

his opinions and to bring them more nearly in harmony with the conclusions of Brooks andlrving.

N. H. Wiuchell's succession is: Keweenawan, Animikie, Norian, 

Pewabic quartzite (all of which are included in the Tacouic), Keewatiu, 

Vermilion, Laurentian (which are included in the Archean or Azoic). 

The Keweenawan is doubtfully called Potsdam, and is, with the Auimikie, placed as the Georgia formation; and the Pewabic quartzite is 

provisionally placed with the Potsdam granular quartz. Included in the 

Taconic are the quartzites of Minnesota, Iowa, Dakota and Wisconsin. 

The part of the succession placed in the Taconic differs from Irviug's succession for this part of the column in that the formations which Winchell 

includes in the Norian and Pewabic are regarded as the great basal gabbro mass of the Keweenawan, between the upper Keweenawan and the 

Animikie instead of below the Animikie. It is not necessary to say 

that Irving regarded all of these members as pre-Cambrian. The succession within the Archean is the same as that of Lawsou, the difference 

being only that Vermilion is substituted for Coutchiching. Also the 

Keewatin elastics, Vermilion schists, and Laurentian gneiss are regarded 

as incomplete conformity, all detrital, and the lower members but more 

metamorphosed than the upper.

Alexander Winchell's succession below the Keweenawan is Huronian, 

Keewatiu, Vermilion and Laurentian. At the base of the Huronian is 

a great structural break. The three lower series are in conformity and 

grade into each other. This is much the same as this part of the succession given by N. H. Winchell, except that one great series, the 

Ogishki conglomerate, is placed by the latter as a part of the Animikie 

(Huronian) while by Alexander Winchell it is placed with the Keewatin.

Doubtless to the minds of many the great thickness of the combined 

Keewatin and Coutchiching of Profs. Winchells and Lawson *will be 

presumptive evidence against the structure which they have worked 

out. This thickness as given by Alexander Winchell is more than 

30,000 feet, while Lawson gives the Keewatiu a thickness of 5 miles and 

the Coutchichiug a thickness of 4 or 5 miles, or in the neighborhood of 

50,000 feet. The manner in which the structure of the Keewatin and 

Coutchiching schists always strike parallel to and encircle the adjacent 

granite masses suggests that these intrusives have developed slaty 

cleavage or schistose structure which has been mistaken for bedding. 

Lawson supposes the intruding granite has iipthrust the beds until 

they noAv stand on end. That both schistose structure and bedding, 

with marked discordance to each other, exist east of Eainy lake is positively maintained by Puinpelly and Smyth.
VAN BISK.] LAKE SUPERIOR REGION. 167

If the objection of great thickness for the Keewatin and Coutchiching has weight, the enormous thickness of over 120,000 feet glveu 

for the conformable system in north eastern Minnesota, on the theory 

that the Keewatin and Coutchiching are conformable and grade into 

the gneissic series, and that all are of sedimentary origin, now folded 

into a simple synclinal structure, will be still more weighty evidence, 

against the correctness of the conclusion reached. It is notable that 

Willis's explanation of the structure at the center of this supposed 

syncliue, Vermilion lake, reverses this and makes it an anticline. 

Lawson does not have to meet this difficulty because lie regards the 

granite and gneiss as irruptive and consequently a series to which the 

principles of ordinary strati graphical geology do not "apply.

From the foregoing statements it might be concluded that lake 

Superior stratigraphy below the Keweenawan is in a greater state of 

confusion than is really the casue, for a closer examination of the various successions shows that many apparent discrepancies are not real, 

if conclusions are not extended beyond the field .studied in each case. 

Confusion has resulted because the conclusions built up from a study 

of a small part of the region have been assumed to apply to the whole, 

and because different names are used for the same thing. The lake 

Superior region is so large that no one has had or can have a detailed 

personal knowledge of more than a small part of it.

UTHOrxXUCAL CHARACTERS OV A/OJC, LAUKKNT1AN, IIL'KOXfAX, KTC.

Before going farther it will be well to summarize the lithological 

characters of the pre-KoweenaAvan rocks included by the various writers 

under the terms applied to the different series in different districts, 

although to a certain extent this will repeat the preceding paragraphs. 

It is here much less easy to make definite statements than in the case of 

the lake Superior sandstone and Keweenawan.

Azoic, as used by Foster .and Whitney and those who followed these 

authors, was made to include everything below the Keweenawan, with 

the exception of the rocks which are plainly igneous. It covered conglomerates, quartzites, slates and marble, as well as the gneisses, 

mica-schists, hornblende-schists, etc.; that is, rocks which vary in 

their character from those which are plainly clastic, as conglomerates, 

to those which are completely crystalline. The granites, syenites, 

greenstones, greenstone slates, iron ore, jasper, etc., were regarded as 

igneous rocks, in part contemporaneous Avith and in part newer than 

the rocks of the Azoic system, all of which were supposed to be of 

detiital origin, but in age earlier than the Keweenawan.

Laurentian, as used by most of the earlier Canadian geologists, covers 

the most of the light colored granites^and coarse grained gneisses. It 

was recognized that these rocks are cut by basic eruptives. This usage 

was followed by many of the American geologists up to the time of 

Brooks, who excluded a large part of the granite and gneiss from the
168 PRB-CAMBRIAN EOOKS OF NORTH AMERICA.

Laurentian, believing tliis part to be of later age and intrusive. Dawson about the lake of the Woods made the same discrimination. 

Irving, in his la'er work, differed from those who preceded him in that 

he included in the Laurentian all the thoroughly crystalline schists, 

with some of the obscure green schist-conglomerates; that is, he placed 

as a part of the Laurentian a large group of finely schistose rocks cut 

by granite veins which had heretofore been taken to be greatly metamorphosed detrital material and had been placed in the Huronian. He 

also regarded as belonging here many of the fine grained crystalline 

schists of a similar character on the north shore, placed by the earlier 

Canadian geologists with the Huronian. For this Laurentian increased 

in magnitude he used the term Archean.. Lawson and the Profs. 

Winchell use the term Laurentian to cover practically the same class 

of rocks as the earlier Canadian geologists, although Lawsou differs 

from them in regard to their origin and age. It was early remarked 

by Macfarlane and later by Whittlesey, Brooks and Kominger that the 

Laurentian of lake Superior differs from that system in eastern Canada 

in containing no limestones, quartzites, iron ores, or other rocks of the 

plainly detrital class. Brooks and Charnberlin remark that it is 

doubtful whether the lake Superior Laurentian is the equivalent of the 

eastern Laurentian of Canada.

The lake Superior Hnronian of the larger number of the Canadian 

geologists includes the quartzites, slates, fine grained green schists, 

all of which are sometimes conglomeratic, and the. pebbles often distorted and metamorphosed. It also includes the mica-schists, horn, 

blende-schists and fine grained gneisses bearing calcite, with certain 

ferruginous schists and basic and acid volcanic products. The attitude 

of the Huronian schists is either vertical or steeply inclined. The Animikie is not included in the Huronian. On the south shore Brooks and

Pumpelly in their earlier work included in the Huronian all the rocks 

in character like those placed in this system on the north shore, with 

also large areas of rocks the clastic character of which is evident, such 

as limestones, ferruginous beds, slates, graywackes, etc., which while 

always tilted or gently folded have not the schistose structure of the 

Huronian of the north shore, but rather resemble the Animikie. Later? 

Brooks placed as the upper member of the Huronian large areas of 

gneiss and granite which had earlier been regarded as Laurentian. 

Eominger went a step farther and recognized in his published report 

on the south shore the Huronian only, seeing as he did that a part of 

the granite-gneiss certainly cuts a portion of the schistose rocks which 

had been regarded as Huronian. He thus included in the Huronian 

the granite-gneisses which are equivalent toLawson's Laurentian, and 

reverted to the position of Foster and Whitney, making his Huronian 

the equivalent of their Azoic, one indivisible system. In Eominger's 

later unpublished manuscript he, howeverj distinctly recognizes besides 

a later intrusive granite an earlier granite-gneiss upon which the lowest
VANHISB.] LAKE SUPERIOR REGION. 160

detrital beds wore deposited, although lie nowhere states whether this 

is coDsidered Laurentian or not. Irving excludes from the Huroni;m 

on the south shore large areas of green crystalline hornblende schists, 

chlorite-schists and green schist-conglomerates cut by granite veins 

heretofore called Huronian; that is, he included in the Huronian only 

those detrital rocks the clastic character of which is apparent or which 

can be traced into the clastic rocks, such as the quartzites, limestones, 

ferruginous beds, argillaceous slates, the raetamorphic mica-schists, 

etc. In his Huronian he included the Aniniikie on the north shore, 

placed above the Huronian by the Canadian geolgists.

Lawson abandons the term Huronian and divides the schistose rocks 

included under this term by the earlier Canadian geologists into two series the Coutchichirig and Keewatin. The Coutchiching includes the 

lowest rocks in contact with the Laurentian gneisses and granites and

comprises mica-schists and fine grained, evenly laminated gneisses; that 

is, thoroughly crystalline finely laminated rocks. The Keewatin includes 

fine grained green schists, both basic and acidic, with volcanic tuffs, agglomerates, peculiar altered conglomerates with intersecting eruptives, 

and jaspery iron ore beds. It does not include the unaltered slates, 

graywackes and ferruginous beds of the Animikie. The position of the 

Profs. Winchell is practically the same as that of Lawson, except that 

instead of using Coutchiching, Vermilion is used, and both the Keewatin and Coutchiching are held to be inferior to all of the Huronian.

The Animikie includes the unaltered, or little altered, gently inclined 

or folded slates, graywackes, and ferruginous beds on the north shore 

and in northeastern Minnesota.

Belonging to the series designated by the foregoing terms are recognized by all writers interbedded and cutting basic and acid eruptives 

of various sorts, only in the Animikie and in the Huronian of Irving the 

acid eruptives are insignificant in amount. Many of the fine grained 

green schists, with some exceptions, in early days regarded as much 

metamorphosed sedimentary Huronian rocks, arenow considered by all to 

be much altered eruptives, either of surface or deep-seated origin, their 

present structure being due to secondary causes. That acid eruptive 

material should be found plentifully cutting the elastics series is not at 

all surprising. Acid eruptions were abundant and widespread in the 

lake Superior region as late as Keweenawan time, as is attested by the 

original acid rocks of the copper-bearing series, and still more emphatically by the vast amountof debris from felsites, quartz-porphyries, etc., 

found in the interlaminated detrital beds. That so few acid dikes are 

found in the upper Huronian of the south shore can be explained only 

by the fact that the acid eruptives of the Keweenawan are mostly remote from the Marquette, Menominee, and Penokee series. A closer 

study in the future will probably show in these districts a greater 

abundance of acid eruptives than has been supposed^ The deep-seated 

pipes and bosses formed by the eruptions of the Keweenawau felsites
170 * PRE-CAMBRIAN ROOKS OF NORTH AMERICA. [BULL. 80.

and porphyries perhaps crystallized in the form of granite. It may 

well be that large masses of intrusive granite may be of Keneewanan 

or Animikie age. Even if this were the case and there are two epochs 

of granitic eruptives later than the upper Huronian elastics, this would 

be no evidence of the absence of an ancient floor composed mainly of 

granite-gneiss upon which the oldest Huronian has been deposited.

ORIGIN7 OF THE IRON ORES.

Before taking up the correlation of the pre-Keweenawan lake Superior series, one further point remains to be considered, whether the iron 

ores and associated rocks are eruptive or are sedimentary, for upon 

this point depends the correctness of many structural determinations. 

If, as believed by Wads worth and Foster and Whitney, the iron ore is 

partly igneous, and by the first named that a part of the jasper has the 

same genesis, they may occur at any horizon up to that of their eruption 

and can not be used as guides in working out the structure. Those who 

believe the iron-bearing formations are sedimentary have regarded them 

as persistent members, and the striking and peculiar lithological characters of these belts have furnished key horizons to which to refer the 

associated elastics.

Foster and Whitney saw that the masses of iron ore and jasper have 

none of the characteristics of vein deposits, and believed that the supposition that they resulted from, the decomposition of pyrites or the 

metamorphism of bog ore is wholly inadequate to account for the 

accumulation of such vast masses as occur, or to explain the relations 

to the associated rocks. If not of this origin, they could only conceive 

that they are igneous. The frequent association of the ore with eruptives and the fine banding led to the conclusion that these facts can 

hardly be explained except by igneous action, These writers saw,

however, that when the ore is found in beds in clearly metamorphi'c 

strata having a common bearing and inclination they must be sedimentary, and such deposits arc regarded as having been derived from the 

destruction of previously formed igneous masses and their present 

association to have resulted from aqueous deposition, so that even in 

this case the iron has an igneous source. "At the present time few 

would assert that the iron ores are vein deposits, or the result of 

decomposition, of pyrites, or the metamorphism of bog ores; but there 

are other explanations overlooked by Foster and Whitney which may 

apply before being driven to the igneous hypothesis.

The reasons given by Foster and Whitney for an igneous origin of 

the ore-bearing formations are of a negative character, and the only 

case in which positive evidence is given the rocks a,re recognized as 

detrital. But Wadsworth brings forward positive evidence as to the 

'origin of the ores. Many instances are cited showing the way in which 

the jasper and ore have eruptive contacts with the associated schists. 

The facts, however, indicate the eruptive character of the ore and jas-
LAKE SUPERIOR REGION. 171

per only if the schists are of sedimentary origin. The investigations 

of Irving, Williams, and the Profs. Winehell, as well as our OAVU later 

work, have shown ;that the lower Vermilion and lower Marquette ironbearing members contain many schistose dikes, and also that in many 

eases the massive greenstone knobs found in these districts vary by 

imperceptible stages into the finely laminated schists associated with 

the iron ore and jasper. The schists are, then, in part at least, of eruptive origin. Brooks noted the dike-like character of certain magnesian 

schists associated with the ore formation, between which and the dioritic schists, believed to be of sedimentary origin, it was said to lie 

impossible to draw the line. That these well laminated schists should 

not at first be regarded as eruptive is natural, but the variation of 

massive igneous rocks into those which are well laminated as a result 

of dynamic action and rneta'somatic changes is now so well known that 

new cases of it excite no surprise. I would by no means assert that 

all of the schistose rocks associated with the iron ores and jaspers in 

the Marquette and Vermilion districts are of eruptive origin, but this 

is certainly the case at many localities. This view reverses Wadsworth's and makes his sedimentary rocks eruptive and his eruptives 

sedimentary. It will, however, be seen that this position harmonizes 

irving's conclusion as to the sedimentary origin of the ores and jaspers 

and the point upon which Wadsworth places most emphasis, that there 

are eruptive contacts between these rocks and the associated schists.

It is to be noted that the eruptive theory has been applied only-to the 

Marquette and Vermilion jasper and ore. No one has asserted such an 

origin for the iron-bearing horizon of the Penokee and Animikie series. 

This is an independent question, as will be seen by what follows; for 

these formations probably occupy a higher position than the lower Marquette and lower Vermilion ores. We have, then, to ansAver two questions: "What is the origin of the iron-ore formations of the Penokee, 

Animikie, and equivalent iron-bearing formations"? "and, second, "What 

is the origin of the great masses of ore and jasper of somewhat irregular shape, apparently not continuous formations, although probably at 

rather persistent horizons, in the Lower,Vermilion, Lower Marquette, 

Kaministiquia, and similar areas'?"

Upon the first of these questions there is practically no dispute. The 

iron-ore formation in the Penokee district has been found to extend for 

many miles as a simple belt of very uniform thickness between two readily recognized detrital formations, all with a common strike and dip 

varying within very narrow limits. A precisely similar condition of 

affairs is found in the Animikie district. These formations have been 

shown by later work to have been originally altogether what they still 

are largely, thinly laminated impure cherty carbonates of iron, in every 

way analogous to similar earthy carbonates of later geological periods. 

The other forms of material now associated with them, such as jasper, 

actiuolitic and magnetitic schists, ore bodies, etc., are the consequence
172 rRE-CAMBRTAN ROCKS OF NORTH A.MERICA. tnuu,.8rt.

of subsequent changes. The ore bodies, for instance, are secondary 

concentrations, generally in troughs, due to the action of percolating 

water. The same facts are apparent as to the Upper Marquette and 

Upper Menominee ores and jaspers.

In the case of the iron formations of the Lower Ma.rquette, Lower 

Vermilion, and similar districts the question can not be so decisively 

answered. The Lower Marquette iron-bearing formation is generally, 

if not always, the uppermost member found in the lower series, when erosion has not carried it away, and therefore apparently occupies a definite 

horizon, although as the structure of this district has not been worked 

out in detail this can not be positively asserted. In the Vermilion lake 

district the great masses of ore and jasper of immense thickness seein 

to extend only for a short distance along the strike of the rocks, then 

disappear and reappear at intervals to the north eastward at Long lake, 

at Hunter's island, and other points, probably also north of Port Arthur 

in the Kaministiquia district. This lack of persistence may be due to 

the fact that the fold or folds are nothorizontal, but ha.ve a varying pitch. 

Th e ore form ation at the s w ells oftl i e pitcl lin g folds in ay have been rein o ved 

by erosion. While it is not proved, it is probable that the ore formation is at a definite horizon, since the different outcrops appear to be in 

the same part of the series and along the same general line of strike 

for considerable distances. These ore and jasper formations contain 

abundant iron carbonate, are interlaminated with graphitic schists containing iron carbonate, the graphite of which is so abundant and widely 

disseminated in minute particles that it can hardly be believed to be 

other than of organic origin, and from these forms there are gradations 

to the other forms of rock found in the iron-beating formation. In the 

deeper workings of some of the larger mines of the Marquette and Menominee districts, the ore bears much residual carbonate of iron and 

also carbonates of calcium and magnesium. At Iron Mountain and 

Metropolitan the iron formation grades downward by insensible degrees into the limestone. All of these points, and the remarkable lithological likenesses between the phases of-rocks found at these horizons 

and those occurring in the iron formations of the Penokee and Animikie, 

demoustrably of detrital origin, axe cited as evidence that these ores 

are derived from an originally impure cherty carbonate of iron. A 

study of the Vermilion iron formation by 1ST. H. and H. V. Winchell 

has led them to the conclusion that it is of direct chemical detrital 

origin rather than derived from an impure cherty carbonate. Which 

of these views is the correct one does not concern the present question, 

for if the ore-bearing formation is detrital it may be used for the purposes of stratigraphy. We thus have in favor of an origin for these 

lower ore formations similar to those of the Penokee and Animikie a 

large amount of positive evidence, while the only adverse positive facts 

are those cited Itjj AVadsworth, and these, as has already been said, may 

be brought into accordance with the sedimentary theory by consider-
VA.VIHPB.I LAKE SUPERIOR REGION. 173

ing the schistose rocks having eruptive contacts with the ores and jaspers as the intrusives, which in many cases they dernonstrablyare. In 

his most recent paper Wadsworth himself suggests that the supposed 

eruptive jasper and ore may be " truly fragmental, their present relations being due to sedimentary and chemical action and the squeezing 

together of the jaspilite and schist."

It was suggested by Brooks that the ore deposits of the ~$ew England-Saginaw range and of the lake Superior mine in the Marquette 

district are secondary concentrations due to the removal of silica and 

the deposition of iron oxide. The same position was taken by Eominger 

for the entire Marquette district. Later I have shown that it is a general 

truth for the lake Superior region that the iron ore deposits are secondary concentrations, produced by downward percolating waters along 

the paths of great water channels, and particularly at places where the 

waters are converged by tilted impervious basement formations.

THE BASIC EllUPTIVES AND STRATIGRAPHY.

At one other point the problem of lake Superior stratigraphy has 

been made-more difficult by certain of the geologists than was necessary. The diabases, diorites, and gabbros were by several writers in 

early days regarded as nietamorphic sedimentary rocks. Logan, Murray, and Foster and Whitney are notable exceptions. Partly as a consequence of this fact came the minute subdivision of the Marquette, 

Menomiuee, Penokee, and other series. All now regarding these rocks 

as intrusives, the facts that they are often in boss-like masses, and when 

interleaved do not necessarily continue for any considerable distance, 

present no difficulty; while a great formation like the Upper Slate of 

the Penokee and Marquette districts is left as a whole rather than divided into a number of members separated by layers of greenstone. 

Also it is now known that the " dioritic schists " are ancient eruptives, 

in part contemporaneous and iuterbedded with the sedimentary it>cks. 

The volcanic character of these rocks was suggested by Foster and 

Whitney, and their igneous origin was appreciated by Eominger. Later 

investigations by Wadsworth and AYilliams, with the microscope, lead 

to the same conclusion.

The intrusions of the diabases, gabbros, and diorites, as suggested by 

Eominger, Wadsworth, andMerriam, have oftentimes had an important 

influence upon the structure of the sedimentary beds, although Eominger holds that the folding is primarily due to the intrusive granite. 

Strong and Eominger also suggested, in the St. Louis river district, 

that the eruptives were the pipes which furnished the outflows of Keweenawan time. This idea is not only plausible for this district, but 

is probably true for the entire lake Superior region. A closer study will 

probably demonstrate that the fresher eruptives in both the upper and 

lower Huron! an, including the great intrusive beds of the Animikie, are 

really Keweenawan in age. Also the numerous dikes of like character
174 PRE-CAMBRIAN . ROCKS OF NORTH AMERICA. [BULL. 83.

cutting the fundamental complex doubtless represent in other series 

the same manifestation of igneous activity.

UNCONFORMITY AT BASE OF CLASTIC SERIES.

In attempting to determine how far the different views held as to lake 

Superior stratigraphy are really in harmony, it is desirable to have, if 

possible, as starting planes upper and lower horizons. From the preceding pages it is evident that for the first of these we have the base 

of the Keweenawan. Nearly all are agreed that below this series is a 

break more or less considerable, and all are agreed that it is a recognizable plane. It appears to the writer that the evidence shows the 

existence of another general plane for the lake Superior region at 

the horizon elsewhere defined as separating the Archean from the 

Algonkian that is, the plane between the basement granite-gneissschist complex and the overlying clastic series with their equivalent 

crystallines. The failure generally to recognize this plane is due to the 

fact that the banded and contorted gneiss, which is the most prominent 

rock of the basal complex, does not differ greatly in Jithological character from areas of later granite-gneiss which have intruded the elastics. This later granite-gneiss is, however, usually somewhat nearer 

the normal form of an eruptive rock, not having suffered so many vicissitudes in its briefer history. Those whose attention has been mainly 

directed to the contact phenomena of the intrusive granite-gneisses 

have generally refused to believe in an earlier granite-gneiss, although 

recognizing, at least in some cases, that the lowest detrital rocks bear 

numerous fragments of a granite-gneiss. On the other hand, those 

whose attention has been directed to. the unconformities, as indicated 

by basal contacts and other phenomena between the basal complex and 

the clastic series, have sometimes been disinclined to believe in the 

existence of important areas of granite-gneiss which are intrusives later 

than the clastic series. Generally, in the districts which have been 

studied by individual writers the phenomena of the one class are conspicuous while those of the other class are unimportant or perhaps 

lacking altogether. Naturally this has engendered an inclination in 

each observer to conclude that the relations which have strongly impressed him are true of the entire lake Superior region.

Bell and Selwyn find no evidence of discordance between their Laurentian. and Huroniau. Bell, in 1873, says the distinction between the 

Laurentiau and Huroniau is chiefly of a lithological character, while 

Selwyn, in 1883, states that he can give no b'etter reason for supposing 

that certain sets of beds belong to the Laureutian and others to the 

Huronian than a considerable difference in lithological character, the 

former being essentially granitoid, gneissic. and feldspathic, while the 

latter is quartzose, hornblendic, schistose, and slaty.

There is, however, much evidence that the plane between the Algonkian and Archean is definitely fixed over much of the lake Superior 

region by a great unconformity.
VANHisB-l LAKE SUPEKIOK REGION. 175

That below the Cherty Limestone of the Penokee series there is a 

great physical break would, in the face of the evidence at present 

known, be hardly doubted by anyone. The cherty limestone, forming 

a single line of outcrops, although not continuous, now rests upon 

granite, now upon gneiss, now upon the green crystalline schists. 

The granite is definitely known to be later than the schists because it 

intricately intrudes them, but it never intersects the cherty limestone. 

This basement is clearly a complex upon, which the limestone has 

been deposited.

Turning now to the Marquette district: Unconformable contacts 

have been found at many localities, but here the clastic series are 

folded, and certain of the contacts between the elastics and crystalline 

complex, by overlapping, are below upper members of the clastic series 

rather than truly basal contacts. Of the two localities cited by Brooks 

for the unconformity between the Huroniaii and Laureutian, that at 

Republic mountain is clearly between the lower part of the Marquette 

scries and the granite-gneiss-schist complex, while that at Plumbago 

creek, in the L'Anse district, is certainly below a high horizon. Of the 

many localities cited by Romiuger and Jrving in which there are contacts between the gianite-gneiss-scliist complex and the overlying elastics, if Brooks's succession be accepted, several belong Avell down 

in, if not actually at, the base of the Ma.rqu.ette series. At these 

contacts the elastics are generally. conglomerates, built up chiefly 

of the debris of the underlying rocks,.and oftentimes so thoroughly 

cemented as closely to resemble them and to lead to the conclusion, if 

not carefully examined, that there is a real transition between the 

clastic and crystalline rocks. As already indicated, this was at first 

Rominger's opinion, and the apparent transition was taken to indicate 

a gradual metamorphism from the conglomerates to the granite or 

schists as the case might be. But Rominger's later studies led him to 

see, as did also Irving, that these basal conglomerates are recomposed 

rocks resting upon an earlier formed crystalline and often granitic; base. 

In the Menominee district Brooks, Rominger, and Irving all hold that 

contacts are found between very low, or the lowest members of the 

clastic series and the granite-gneiss complex, the relations being those 

of profound unconformity. The actual contact described by Smyth 

(too late to summarize in the literature) between the lowest formation 

of the lower Marquette and the granite-gneiss at Republic mountain 

is the clearest case on the south shore. Here is a basal conglomerate 

containing numerous water-worn bowlders and pebbles of granite, resting directly upon the granite from which the fragments are derived.

As shown by Irviug, the magnitude of the break in the Penokee, 

Marquette, and Menominee districts is not lessened whether the underlying schist, gneiss, and granite are igneous or sedimentary, for they 

had reached their present crystalline condition before the overlying 

rocks were deposited upon them, a condition which a part or all
176 PKE-CAMBRIAN ROOKS OF NORTH AMERICA. . [BULL.86.

could not have had as surface rocks; and "which shows, whether igneous or aqueous, profound induced structures and deep erosion, and 

therefore a system of rocks which had an intricate history before the 

elastics were deposited. In this connection the-physical break at the 

base of the Animikie and its equivalents is not cited, because this 

series occupies a higher position than the series overlying the break 

just considered.

As further evidence for a great physical break between the basement complex and the lowest overlying elastics are cited by Brooks and 

living (1) the strong contrast in thejithological characters of the two, 

the fundamental complex being thoroughly crystalline, while the overlying rocks are mainly plainly detrital, or such as may have been 

derived from detritals; (2) the fact that the complex is cut by very 

numerous granite dikes, which''are but rarely found in the elastics; 

and (3) their general field relations, the complex having most obscure structures and very great variability in strike and tip, while 

the elastics are less intricately folded, showing that the older series 

has been subjected to orographic movements prior to the newer.

As before stated, Brooks, liominger, and Irving the three who have 

done the most detailed and continuous work on the south shore had 

at the outset different opinions as to the relations of the elastics to a. 

basement granite-gneiss, but they all came to the same final conclusion, that between the two is a great structural break. Pumpelly and 

Ohamberlin, who have also done much general work in this region, 

agree with this conclusion. While this is true, all of these writers do 

not agree in every district as to the position at which this plane is 

found.

Whether the physical break which exists below the clastic series 

on the south shore is paralleled by a widespread unconformity on the 

nortli shore is less certain, although such an unconformity is found 

locally. Lawson, who has done the most work in this region, maintains 

that between the Keewatin and Coutchiching a profound physical 

change took place in the conditions of deposition, consequent upon 

which are great differences in lithological characters and a prevalent 

more crystalline condition in the inferior series. He also describes 

conglomerates in two places at the base of the Keewatin which bear 

both granitic fragments and fragments from the Coutchiching. From 

these facts Lawson believes that there is a real unconformity between the two series, although at the present time they have been so 

squeezed together and secondary structures formed as to be usually 

in apparent conformity, and the separation in mapping is based for 

the most part upon lithological grounds. Lawson, however, believes 

that the Coutchiching is a bedded sedimentary series, rather than a 

part of the basal complex, as here defined. If this be true,this unconformity docs not bear on the question under discussion.

Pumpelly and Smyth, who have recently made a rather extended trip
VANHISE.] LAKE SUPERIOR REGION. 177

in western Ontario, acquiesec in Lawson's conclusion in so far as tlie 

unconformity is concerned, but differ from Lawson in that they find a 

great structural discordance between the basal clastic series east of 

Rainy hike and a fundamental complex consisting of granite, gneiss, 

and schist, while finding the superinduced foliation of both series 

parallel.

In Minnesota the Profs. Winchell, although recognizing the plane 

between the elastics and crystallines as a boundary between two groups 

of rocks, maintain conformity and gradations, although Alexander 

Winchell suggests that it is a possibility that the apparent conformity 

is superinduced by subsequent dynamic action.

The probability of an unconformity here follows from the same line 

of reasoning as that applied to the lake of the Woods and Rainy lake 

districts, and is further indicated by the descriptions of conglomerates

at Saganaga and .Epsilon lakes in northeastern Minnesota by Alex. 

Winchell. In the published note-books these conglomerates are 

described and figured as sharply separated from the underlying syenite 

and containing rounded pebbles of it, although it is said the conglomerates were not laid down on the solidified syenite. Later these occurrences are interpreted to mean that the syenite and gneiss are of sedimentary origin, being completely metamorphosed. However, I am not 

sure that I understand the descriptions well enough to be certain that 

these so called conglomerates are not really due to the intrusion of the 

later irruptive syenite, as was suggested by Winchell himself. In the 

earlier work on the north shore of lake Superior done by Bell, no distinction was made between the ftue grained elastics and the crystalline 

schistose rocks, although it is not improbable that closer work will make 

impossible to extend the structural subdivisions of Pumpelly and Smyth. 

Macfarlane noted that the squeezed Huronian slate conglomerates frequently contain granite fragments, although he did not consider them 

to be of sedimentary origin. Herrick found in his schistose group on 

Michipicoten bay basement conglomerates, the pebbles of which are like 

the granite below, although the relations between the granite and 

schists are such as to suggest to him that the granite had been intruded 

beneath the schist. Dawson (Sir William), Logan, and Bell all mention 

granite and gneiss fragments in the Original Huronian east of lake 

Superior, and Logan clearly believed the two to be unconformable. 

Irviug found additional evidence in favor of this unconformity. Recent 

work of Pumpelly and myself has shown that the lowest member of 

the Original Hurouian, as mapped by Logan, rests with a great unconformity upon the basement complex, the Laurentian of Logan. Selwyii, 

although thinking the Huroniaii and Laurentian conformable, states 

that Laureutian pebbles occur in the Huronian.

As shown in another place, the gradation described by the Profs. 

Winch ell in northeastern Minnesota, and which appears to occur in 

other places, is wholly consistent with a real structural break between 

Bull. .80 12
178 rRE-CAMBRIAN EOCKH OF NORTH AMERICA. [DULL.80.

the basal complex and the elastics. When a clastic series grades down 

into a crystalline one, this may be caused by progressive metarnorphisin> 

by contact action of a subsequent intrusive, or by later folding, which 

destroys the original bedding of both series, and produces a common 

secondary structure, at the same time can sing the newer series to assume 

a crystalline character. Such induced conformity and traii si tion are the 

more likely to occur when the materials of the newer series are chiefly 

derived from the older, and, as shown by Pumpelly, will be particularly 

likely to be perfect when the earlier series has suffered atmospheric disintegration before the deposition of the later. Future study may show 

still other causes of gradations between un conform able series.

Evidently north and east of lake Superior we are not without positive evidence that a great physical break occurs at certain points 

between an ancient granite-gneiss-schist complex and the clastic series, 

which, however, are often cut by recent intrusive granite-gneisses. Also 

at many localities in which an unconformity has not been positively 

shown the evidence at hand points in this direction. When the conditions are considered which are necessary to produce an unconformity 

it is difficult to see how one can really be of a local nature. Thus while 

it can not be asserted that a universal structural break north arid east 

of lake Superior exists between the Algonkian and Archean, there is 

a probability that such is the case.

The foregoing evidence combined gives a strong case of probability 

for a general structural break in the lake Superior region between the 

lowest clastic series and a basement crystalline complex. However, it 

can not be denied that certain of the contacts, cited as showing this unconformity, although unquestionably beneath the lowest clastic series 

for particular districts, may be at higher strati graphical positions than

the base of the lowest clastic series of the whole lake Superior region,

Before the question of a break at this position can be considered as settled beyond all question for the entire lake Superior region much 

more detailed mapping must be done. However, the existence of this 

break tor many districts is so strongly supported, that it gives for the 

present the best available guidance as to one fixed horizon for comparisons of the rock series of the different districts. The recognition of this 

break does not imply that the lowest clastic series at certain localities 

ftre not penetrated by, and now rest upon, intrusive granite-gneiss, but 

in such cases the evidence of this break, if it once existed, has been destroyed.

We have, then, for structural work two starting planes, the base of the 

Ke ween a wan and the base of the elastics, included between which are 

the larger part of the series of rocks placed in the Huronian by the 

earlier Canadian geologists, the Auimikie, Lawson's Keewatin the Profs. 

AVinchell's Keewatin and Animikie, living's Huronian, and perhaps in 

part the Profs. Winchells' Vermilion and Lawson's Gout-cinching.
VAXITISE.] .LAKE SUPER TOR REGION. 170

UNCONFORMITY WITHIN CLASTIC SERIES.

Jt is believed that many of the further difficulties as to correlation in 

the districts about lake Superior have arisen from the failure to recognize a third physical break which has a very wide, if not universal, 

extent in this region. The early Canadian geologists found a break at 

the base of the Animikie, and while this series was first placed with 

the Huronian, the fact that unconformably below it was another series 

Avhich also resembled the Huronian led the later Canadian geologists 

to exclude the entire Animikie from the Huronian, and they have thus 

restricted the term in this district to the pre-Animikie Huronian rocks. 

The Michigan and Wisconsin geologists include in the Huronian the 

equivalents of both the Animikie and pre-Animikie Huronian, and while 

facts were clearly contained in their reports pointing to a discordance 

within the rocks referred to the Huronian no attempt was made to 

carry these facts to their conclusion and to subdivide the series. But as 

early as 1883 Irving saw that there is a series of green schists and 

scliist-conglomerates which must rest discordantly below other rocks 

recognized as Huronian, as shown by their attitude and degree of crystallization, as well as by the fact that they had yielded fragments to 

the newer formations. As a consequence of this he was led to exclude 

from, the Huroniau these lower schists, which had before been everywhere accepted as Huronian. Lawson, in 1886, saw that his Keewatin 

series is fundamentally different from parts of the original Huronian, 

and especially from the Animikie series, and was led to refer it to the 

Huronian series only doubtfully; at the same time he saw that the 

Keewatin is like the Dore" river series at the east end of lake Superior, 

and suggested that possibly Logan and Murray had placed in the 

Huronian two discordant series. Alexander Winchell, in his last 

paper, which appeared almost simultaneously with his death, announced 

definitely that two series had been confounded in the Huronian.

We will now consider the evidence for a physical break within the 

rocks which have generally been referred to the Huronian.

Evidence of this break in the.Marquette district was first noticed by 

Foster and by Foster and Whitney, who found over the ore horizon at 

what has since become the Eepublic mine, and one or two other localities, a conglomerate bearing fragments of the ore, jasper, and other rocks 

associated with the iron ore. It Avas next noted by Kimball, who 

.mentions beds of specular conglomerate. Crediier describes, over the 

iron .formation at Michigamme mine, a conglomerate, the fragments 

of ja,sper and quartz being in an iron and quartz base. Brooks 

describes the upper quartzite of Eepnblic mountain and that at the 

New England mine as a conglomerate containing fragments of ore. 

By Eomiiiger the break was noticed at so many places that he remarked that above the iron-bearing rock is generally a very coarse 

qnartzite-congionierate \vhich often has the character of a coarse-
180 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

grained ferruginous quartzite, the fragments of which are chiefly ore, 

jasper and quartz. This occurrence is so general as to suggest to this 

author that great disturbances not of a local extent must have occurred 

at the end of the era of iron sediments. Wadsworth says that these 

conglomerates mark old water-worn, beaches after the jasper and ore 

were in situ in nearly their present condition. Believing in the eruptive 

origin of these rocks, Wadsworth did not regard the conglomerates as 

evidence of the existence of more than a single series. Recently this 

author has changed his opinion in this particular. Irving recognized 

the break, and the fragments included in the conglomerate overlying 

the iron belt are said to prove the existence of the jaspery and chalcedonic material in its present condition before the formation of the upper 

quartzite. Lately the break was noticed by the Profs. WincheJl, and 

N. H. Winchell regarded it as so great that the rocks above the break 

were provisionally referred to the Potsdam. The writer has described 

the break as of universal extent and as representative of a great unconformity, for the banded and contorted jasper aud ore are found to abut 

perpendicularly against a quartzite bearing abundant fragments of the 

underlying formation, which are in exactly the condition there found. 

The lower series is a semicrystalline, much folded one, while the upper 

series has usually not become crystalline nor closely folded. Before the 

upper series was deposited the lower series was folded and truncated.

It is, then, plain that in the Marquette district, within the rocks which 

have heretofore been referred to the Huronian, are two series. Below 

the break which separates them are the lower quartzite of Brooks, the 

associated novaculite and limestone, and the loAver ore-bearing formation, including the hematitic, magnetitic, and actiuolitic schists and jaspers, which contain the larger number of great mines. Above the physical break are Brooks's upper quartzite, the base of which is generally 

the conglomerate already described. Over the upper quartzite follow 

the black slates, sometimes carbonaceous, gray wackes, and mica-schists, 

together of great thickness, and occupying an area as large as or larger 

than the Lower Marquette series. In these upper slates, apparently at 

rather persistent horizons, are locally belts of chert aud iron carbonate 

associated with ore bodies of considerable size. These ores are, however, of a very different character from those which occur in the lower ore 

formation.

In the Menominee district as evidence in favor of a physical break 

within the clastic series are the conglomerates described by Brooks at 

the Pine and Poplar rivers district, and in the Common wealth section. 

At the first is found conglomeratic quartz-schists, containing micaceous 

iron and magnetite; in the second are included conglomeratic quartzschists, containing pebbles of white quartz (chert) and jasper. Similar jasper conglomerates have been found by Pumpelly and the writer 

over the ore at certain of the mines. The relations here are, then, exactly like those in the Marquette district. Also, the structural break
VANHISE.] LAKE SUPERIOR REGION. 181

indicated by these conglomerates is supported by Brooks's mnjor divisions of the Menoininee rocks. His inferior Huroiyian comprises the 

lower qua.rtzite of great thickness, a great marble formation, and the 

great iron-ore horizon, consisting of inagnetitic, hematitic, a/nd jaspery 

schists, with deposits of iron ore. In this formation are the Norway, 

Qninnesec, Ludiugton, Chapin mines, etc. Brooks's middle Huronian, 

presnma.bly above the unconformity, includes quartzites, clay-slates, 

and obscure soft schists. Within these soft slates is the upper ironbearing horizon, including such mines as the Commonwealth, those at 

Crystal falls, etc.

In thePenokee district this unconformity is represented by the basal 

conglomerates of the Quartz-Slate member, containing numerous fragments of chert and a few of jasper, which Avere in their present condition 

when derived from the Gherty Limestone and Iron-bearing members. 

The lower series is now represented by the Clierty Limestone member 

alone, while the upper series includes the Quartz-Slate, Iron-bearing, 

and Upper-Slate members.

That there is a similar unconformity within the clastic series between, 

the Lower Vermilion, Hunters island, and Lower Kaministiquia series 

and the conglomerates at these places bearing abundant material 

derived both from the ore-bearing formation and from the green schists, 

is inferred because the water-worn fragments of schist, jasper, and ore 

are in precisely the same condition in the conglomerates that they are 

in their original position. In none of these places have actual contacts 

been described. The unconformity is further indicated in the Vermilion 

lake district by a strongly developed schistose structure in a nearly 

vertical position in the Lower Vermilion series, while the overlying conglomerates at places on the islands of Vermilion lake are found to be 

gently folded.

The Avork of the Profs. Winchell also gives evidence of this unconformity. N. H. Winchell, in tracing the flat-lying Animikie series to 

the westward from Gunflint lake, finds that it becomes more steeply inclined and takes on, at times, a slaty cleavage. It is traced as far as 

Agamok lake, near the great Ogishki conglomerate, and the latter is 

consequently placed with the Animikie. To these statements Alexander 

Winchell agrees so far as to Agamok lake, but places the Ogishki conglomerate as a part of the Lower Vermilion series, for he traces this conglomerate all the way to Vermilion lake and he recognizes no break between the Vermilion lake conglomerate and the Lower Vermilion. Taking the positive evidence given by Profs. Winchell and disregarding 

their partial conclusions, it would seem to indicate that there is a gradation and actual continuity between the flat-lying Animikie and the 

conglomerates with a vertical superinduced structure at Ogishki and 

Vermilion lakes. That between the Animikie and the Lower Vermilion 

there is a great physical break is now denied by no one, and if the foregoing reasoning is true, it shows that this break is a continuation of
182 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BCLL.8&

the one between the Lower Vermilion and the Upper Vermilion which 

bears fragments of the lower series. The only published detailed succession of the Vermilion series is that by Willis. His chloritic schists 

and jasper (I, n, and in) belong in the lower series, while his conglomerate and black clay-slate (V and vn) belong in the upper series. 

The position of the niagnetitic quartzite (iv) is uncertain, while the 

quartz-diorite (vi) is probably an eruptive rock.

It has been long well known that near Port Arthur, Ontario, the 

Auiniikie and underlying Kaininistiquia series are unconformable. 

McKellar, who for many years has been familiar with this district, has 

proved this conclusively. Therock series here unconformably underlying 

the Animikie are identical with the Vermilion lake iron-bearing series.. 

Considering the foregoing evidence and the complete likeness of this 

lower series with that bearing iron at Vermilion lake, it can no longer 

be doubted that there is a great physical break between the Animikie 

and Lower Vermilion series in northeastern Minnesota, although the 

equivalence of the Auimikie and Upper Vermilion may yetbe maintained..

In the last few years the difference of .opinion has been sharp as to 

the equivalence or nonequivalence of the Auimikie with the Vermilion 

lake and equivalent iron-bearing series. Irving has maintained that 

the Animikie series in its lithological character is like the Penokee and 

Marquette, these like the Vermilion, and therefore the Animikie in all 

probability the equivalent of Penokee, Marquette, and Vermilion.. 

Alex. Wiuchell, having visited the Lower,Marquette series and seeing 

but little of the ground in which the Upper Marquette is found, and 

consequently not appreciating that in area and in volume this series 

probably surpasses the Lower Marquette, has maintained that theMarqnette rocks are the equivalent of the Vermilion lake iron-bearing series, but that the Animikie series is separated from that at Vermilion 

lake by a great unconformity. He, however, appreciated that in the 

Marquette district are certain slates which in lithological character are 1 

like, and might be equivalent to, the Animikie. Both Irviug's and 

Winchell's positions probably have an element of truth and an element 

of error. The Upper Marquette, Upper Vermilion, Upper Hunter's 

island (Ogishki), in their lithological characters and gentle folding, are 

closely analogous to the Animikie, and, as maintained by Irving, are 

its probable equivalent 5 while the Lower Marquette and Lower Vermilion lake, as maintained by Alex. Winchell, uuconformably underlie 

the Animikie. The physical break within the clastic series in the 

Marquette, Vermilion, Hunters island, and Kaministiquia districts isy 

then, provisionally identified with the great physical break recognized 

by everyone at the base of the Animikie.

It is only fair to say that Lawson considers the unconformity at the 

base of the Animikie at a higher horizon than the physical break described in these various districts. He regards the Animikie series as 

separated by another great unconformity from the Upper Marquette,
VAXHISK.J LAKE SUPERIOE REGION. 183

Upper Vermilion, Upper Kaministiquia, etc. To the writer there seem 

grave difficulties, based on general relations, in the way of accepting 

this conclusion. On the other hand, the Upper Kamiuistiquia conglomerates, not far distant from the ordinary-phases of the Animikie rocks, 

have a decidedly different appearance. This may, however, be due to 

the fact that certain of these conglomerates are of volcanic origin, the 

chert and jasper of which appear to have been broken from their beds 

by volcanic action and mingled with lava and volcanic ash. This sudden 

change in the character of the beds of the same age is parallelized in the 

Penokee di strict, where tl i e strata, wi thin a di stance of a feAv inil.es, rapidly 

change in character, become immensely thick, and are largely in the 

nature of agglomerates, greenstone conglomerates, etc. But it must be 

said that such detailed mapping has not been done adjacent to the 

National boundary of northeastern Minnesota and Ontai-io and in the

Thunder bay district as will warrant any positive statement as to 

whether within the clastic series, between the base of the Keweenawan 

and the Basement Complex, there is another higher physical break, 

making two unconformities which separate the rocks into three series. 

The ore, chert and jasper conglomerates used as evidence of physical 

breaks within the clastic series are not to be confounded with the 

purely volcanic conglomerates which may occur at any hori/on. Also 

the occurrence of these conglomerates will have no such meaning as here 

assigned by those who believe that the ore, chert and jasper in their 

present condition are igneous rocks. To such they will be no more evidence of two series than that the Keweenawan conglomerates, the fragments of which are derived from contemporaneous traps, are evidence 

of many series. But to those who think the evidence is sufficient for 

the belief that the ore, chert and jasper are not only sedimentary rocks, 

but sedimentary rocks which have gone through a long and complex 

history, the evidence of a physical break furnished by these conglomerates will be satisfactory.

CORKKLATIOX; (JKNKliAL COXS1DKKATIONS.

We pass now to the general correlation of the lake Superior formation lying between the two planes already defined, the base of the 

Keweenawan and the top of the Archean schist-gneiss-granite complex.

Before it can be decided whether series so far distant from each 

other as the Dakota quartzites and the Original Huron i an (separated, 

by 800 miles) can be parallelized, it ought to be more definitely settled 

to what extent correlation can be made by unconformities andlithological likenesses. Trying inclined to the belief that such structural breaks 

as that described in the Marquette district are of great extent, and this 

accords with the general trend of modern structural work. From what 

has gone before it appears exceedingly probable that the structural 

break between the Upper and Lower Marquette is identical with that
184 PRE-CAMB'RIAN ROCKS OF NORTH AMERICA. [BULL. 86.

which separates, even in a more pronounced manner, the Animikic and 

Kaministiquia series and the upper and lower Vermilion lake series 

on the other side of the lake Superior basin. The break, being thus so 

strongly marked at points so far separated, would argue that it extends 

over a very considerable area of the lake Superior region, not improbably from the most distant rock series before mentioned, the Dakota 

quartzites and the Original Huronian of the north shore of lake 

Huron. It would not be expected that a like succession is now recognizable in,each of the areas parallelized, even if they all belong to the 

same geological series. In the first place, the rocks in some districts 

are not sufficiently tilted to make it certain that all of the layers are 

exposed. Further, nine-tenths or more of the surface of the country 

over large areas is heavily covered by the drift, so that it is all but 

certain that some of the formations which exist a.t the rock surface have 

not been discovered. Still further, no satisfactory explanation has yet 

been made of the subordinate succession of formations in the Marquette, Felch mountain, Menorninee and Vermilion lake districts; so 

it is not yet known how far the order found in one of the districts is 

equivalent with that of another. From recent work it is probable that 

future investigations will show that this likeness is greater in the 

series below correlated than has been suspected. But even supposing 

the disagreements are as great as the present known facts might lead 

one to suppose, it would not be any very strong evidence against the 

correlations; for it is not to be expected that the same conditions of 

sedimentation have prevailed at all times in a geological basin 800 

miles in diameter. While in one part of the basin fragmental sediments were accumulating, it would not be very strange if chemical 

sediments or organic sediments were accumulating elsewhere. Below,

it is seen that the Penokee and Animikie series are the equivalents of

each other in the broadest sense of the term. It is not necessarily true 

that sedimentation began or ended simultaneously in both districts, but 

only that in the main they stand as time equivalents. How far a correspondence can be made out among the subordinate members of the various districts can be determined only by a detailed investigation of each 

of the areas.

EQUIVALENTS OF THE ORIGINAL HURONIAN SERIES.

Passing now to the Original Huronian, shall this series be correlated with the Upper or Lower Marquette, or is it the equivalent of 

both?

Alex. Winch ell lately announced that the Lower Slate conglomerate and the underlying formations of the Original Huronian are separated froin the Upper Slate conglomerate and the overlying formations 

by an unconformity. No contacts are described, the conclusion being 

based upon general relations. No characteristic debris of the Lower 

Huronian is said to occur in the Upper Huronian. The locality at which
VANHISB.I LAKE SUPERIOR REGION. 185

the strongest evidence is brought forward is on the outskirts of the 

Original Huronian, and a part of the formation which Logan and Murray have mapped as Lower Slate conglomerate is placed by Winchellas 

Upper Slate conglomerate. The observations of Pumpelly and myself 

at a contact between the limestone formation and the Upper Slate conglomerate tend to confirm Winchell's conclusion, but since limestone, 

fragments are plentiful in the Upper Slate conglomerate, we place the 

physical break just above this lower limestone, i. e., 300 feet higher 

than indicated by Wmchell.

The term Original Huronian as here used is strictly confined to the 

areas first described by Logan and Murray on the north shore of lake 

Huron, and in 1863 mapped in detail. The Original Hurouian only is 

here compared with the series about lake Superior because it is the 

area to which the term was first applied, and also because it has been 

more thoroughly described and mapped than any other area in Canada 

designated by the term Huronian. . A careful field and laboratory study 

of the rocks of the Original Huronian has shown its upper series to consist in great part (1) of fragmental quartzites, the induration of which 

has been caused by deposition of interstitial silica; (2) of graywackes 

and graywacke slates (often conglomeratic Logan's Upper Slate conglomerate), the induration of which is due to the deposition of interstitial silica and metasomatic changes in the feldspar; (3) of cherty limestones, and (4) of eruptives. The Lower Huronian series is more metamorphosed than the Upper.

In its readily recognized fragmental character and in its gentle folding the upper Original Huronian series, i. e., the upper 13,000 feet, is 

closely analogous to thePenokee, Upper Marquette, and Auiinikie, while 

the Lower Huronian may be compared with the Lower Marquette and 

Lower Vermilion iron-bearing series. In the order of succession of 

formations it can not be said that either series corresponds very 

closely with the series about lake Superior, to which, they are compared.

It seems to us that in correlation the unmetamorphosed character of 

the Upper Huronian is a guide of some importance. As pointed out by 

McKellar, the intense folding to which the Vermilion lake and Kaministiquia series have been subjected must have preceded the much 

more gentle synclinal movement which formed the basin of lake Superior. That no violent dynamic movement has occurred since the beginning of Animikie time is known to be true of the lake Superior basin, 

and it seems exceedingly probable that the gently folded upper members of lake Huron belong with those of like character about lake 

Superior. If this is not the case, the intense dynamic movements 

which produced the closely folded rocks of northeastern Min.nesotaa.nd 

Ontario lost their force before reaching the area about lake Huron, and 

this region must have escaped any serious folding for a longer time than 

any other closely studied part of the earth's crust.
186 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [M.'JJ,.M.

Besides the reason already mentioned for placing1 the upper Original 

Huronian as the equivalent of the Animikie and Upper Marquette rather 

than below these series, as advocated by certain geologists, we have one 

characteristic feature already cited which is of some weight. One of the 

most peculiar rocks of the Upper Original Huronian is a conglomerate 

which carries numerous fragments of blood -red jasper. At present the 

source of these fragments is unknown unless they come from the ironbearing formation of the Lower Huronian. From what has gone before 

it is apparent that a jasper conglomerate is the basal member of the 

Upper Marquette series, and also that similar conglomerates occur in a 

like position, in Ontario and northeastern Minnesota. Considering the 

widespread character of this jaspery, cherty, and iron-ore conglomerate, its occurrence in the Upper Huronian of lake Huron suggests that 

this jasper may there be found in the future in the Lower Hnronian in 

large quantity. This series would therefore, in position and in lithological character, be like the Lower Vermilion and Lower Marquette ironbearing series. The existence of such a jasper-bearing series was 

inferred by Logan himself. Taking the Original Huronian north of 

lake Huron as a whole, if Winch ell's general conclusion that it consists of two unconforinable series be correct, the analogy between this 

district and the lake Superior region is complete. Above the fundamental complex and below the Keweenawan, as about lake Superior, 

are two discordant series.

EQUIVALENTS OV THE SIOUX QUAKT/ITKS, ST. LOUIS STATES, ETC.

Much of what has been said to- show that the Upper Huronian series 

is the equivalent of the Animikie, Upper Vermilion, and Upper Marquette applies with equal force to such rock series as the Chippewa 

quartzites, the Baraboo quartzites, the Sioux quartzites and the St. 

Louis slates. None of these series are closely folded, although often 

dynamic movements have developed slaty cleavages. Also their original fragmental character is always seen under the microscope at a 

glance. Between these series and the Potsdam is a great unconformity. They present thick beds of fragmental rocks, the induration of 

which has been caused by the same process which \7 itrified the quartzites of the upper Original Huronian. The supposed absence of ferruginous rocks in these districts has been used in the past as an argument 

against the correlation of them with the Penokee and Animikie series

considered, but this absence has no particular weight because 

such beds, as compared with the mechanical sediments, are insignificant 

in amount; and further, it is quite possible that these formations may 

in the future be found in several or all of these districts. This probaability is rendered greater by recently developed ferruginous beds 

between the two quartzite ranges of Baraboo and in the northward 

extension of the St. Louis slates. The rocks here found are the exact 

parallel of the iron-bearing beds of the Penokee and other iron-bearing
VANHISE.I LAKE SUPERIOR REGION. 187

districts. The percentage of iron is so great in certain localities that 

the material is being mined for an ore. For placing these rock series 

with the Keweenawan, as has sometimes been done, there is neither 

lithological nor structural grounds. In the character of the material of 

which they are composed, in the presence of iron formations in certain 

localities and in their induration, they differ profoundly from any of 

the rocks known to belong with the Keweenawan.

No one has placed these series lower in the geological column than 

Upper Huronian, so perhaps it is not necessary to give evidence that 

they are not Lower Hnrouian. The occurrence of chert and jasper 

fragments in the Chippewa quartzites, mentioned by Sweet, and the 

presence of abundant identical material in the quart/ites of southern 

Minnesota and southeastern Dakota, at least show that before the formation of these series there was a prior series bearing chert and jasper. 

Such a series is the Lower Hnronian.. These series then in degree, of 

induration, amount of folding and in lithological character are like the 

Upper Hnronian.

SUCCESSION AND EQUIVALENTS OF THE PENOKEE AND AMMTKIE DISTTUCTS SEIMKS.

In the Penokee district of Michigan and Wisconsin is the following 

succession: At the base isa granite-gneiss-schist complex. The schists 

are always completely crystalline, although often iinely laminated or 

foliated. The granites, with granite-gneisses, an d the fine grained green 

hornblende-schists, mica-schists, and chlorite-schists occupy large separate areas, with a debatable ground along their borders. The contacts 

of the granites and granite-gneisses with the crystalline schists are 

eruptive ones, the former being clearly the intrusives. Above this complex, and separated from it by a great unconformity, is a Cherty Limestone member which in places is 300 feet thick. While it extends east 

and west many miles, it is not longitudinally continuous. Above this 

Cherty Limestone, separated by an unconformity, is the Penokee series 

proper, which consists of a Quartz-Slate member, the upper horizon of 

which is a vitreous quartzite, an Iron-bearing member, and an Upper 

Slate member. Above the Penokee series, separated by another very 

considerable unconformity, is the Keweenawan. The parallelism between this district and the Marquette already described is at once manifest. The Penokee series proper is the equivalent of the Upper Original Huronian, Upper Marquette and their equivalents; the Cherty 

Limestone member stands as the only known equivalent of the Lower 

Marquette; for in the Penokee district the upper members of the equivalent of the Lower Marquette have not been found or have been removed 

by erosion. That the latter is not improbable is indicated by the very considerable thickness in some places of the cherty limestone and its absence in others, while numerous fragments of it are found in the basal 

member of the Penokee series proper. These fragments are so abundant in places as to constitute a true basal conglomerate. They are well
188 FEE-CAM BRIAN ROCKS OF NORTH AMERICA. [DULL. 86.

rolled and are mostly of chert, but are sometimes jasper. This chert and 

jasper, whatever their origin, were in their present condition before 

the deposition of the Penokee series proper.

Further, the relative geographical positions of the Penokee, the 

Upper Marquette, and the Chippewa quartzite districts are such as to 

strongly suggest that they were once connected. The Peuokee series 

at the east is cut off by the uncouformably overlying lake Superior 

sandstone: but east of the south end of Gogebic lake there are here 

and there outcrops of slate which are like the Upper Slate member of 

the Penokee district, and a short distance to the east the na.rrow belt 

spreads out into the broad a>rea of upper fragmental rocks, of which 

the Marquette and Menominee districts are arms. At the west the 

Penokee series has been entirely swept away by erosion, the copperbearing rocks coming in contact with the underlying gneisses and 

granites; but to the southwestward appear the fragmental quartzites 

of the Chippewa valley, which are believed to be its continuation.

The equivalency of the Penokee series with the Animikie is as plain 

as the equivalency of any two areas of detached rocks in a single geological basin can possibly be in which is lacking clear paleontological 

evidence. It has been seen that above the cherty limestone of the Penokee series is an erosion interval. In the Animikie series proper we 

know of no equivalent to this member, and in what follows it is excluded 

from the discussion. The Peuokee and the Animikie rocks have a parallelism in lithological characters which is most remarkable. Not only 

is there a general likeness between the specimens from the two regions, 

but almost every phase of rock from the Animikie series can be matched 

by specimens from the Penokee series. In the Animikie district the 

formations underlying the iron-bearing belt are not extensively exposed, 

and consequently little is known of the Animikie equivalent of the 

Quartz-Slate of the Penokee series. But along the Lower Current 

river, near port Arthur, Ontario, quartz-slates underlying the ironbearing member are found which resemble certain phases of the Penokee quartz slate. Beginning with the iron formations, the parallelism 

between the two series is almost exact. The irony beds upon Gnnflint 

lake, where are found the best known exposures of the formation, are 

in their lower parts jasper, magnetite-actinolite-schist, and cherty ferruginous rocks containing more or less iron carbonate. Higher up are 

thick layers of thinly bedded cherty iron carbonate. All these varieties of rock are found in the iron formation of the Penokee series, and 

at many places the order of succession is the same. Above the ironbearing belt in both districts is a great thickness of fragmental clayslates and graywacke-slates which are again practically identical in 

character in both districts. It is true that in the western part of the 

Penokee district mica-schists have developed from these slates, but the 

original condition of these rocks was essentially like that of the unaltered phases.
VAN HISE.I LAKE SUPERIOR KEG I ON. 189

Underlying both the Aniinikie and Penokee series is a complex of 

granites and schists, the unconformity between which and these series 

is of the most pronounced character. That the Auhnikie series is thus 

separated from the underlying rocks has been seen by all who have 

studied it. Above both series follows the Keweeuawan. In both districts, in passing at any place from the underlying rocks to theKeweenaw series in section, the two are in apparent conformity; but, Avhen 

the lines of contacts between the iron-bearing and the Keweenaw 

series are followed for some distance, both with the Auimikie and 

Penokee series, this apparent conformity is found to be illusory. That 

is, the Keweenaw series is found to come in contact with one member of 

the underlying series atone place and with another member at another 

place, until in both districts at one or more places the entire iron-bearing 

series is cut off, the basal Keweenaw rocks coming directly in contact 

with the fundamental complex. These relations mean that between 

the deposition of the Penokee and Animikie series and the outflows of 

Keweenaw time there intervened a period of erosion which was sufficient in places to remove the whole of the inferior series and to cut 

in some places quite deeply into the fundamental complex. There is 

then an immense time gap between these series and the Keweenawan, 

although this unconformity does not approach in the length of time involved to that separating the Aniinikie and Penokee series from the 

underlying schists and granites.

The Animikie series in its most typical development extends from 

Gunfli lit lake on the national boundary, between Minnesota and Ontario, 

to Thunder bay, lake Superior. The Penokee series lies upon the opposite side of lake Superior. The latter is a simple unfolded succession 

dipping to the northward under the lake; the Animikie is another such 

succession dipping to the southward under the same body of Avater. 

There is then little doubt, considering all the facts, that the two series 

represent a single period in the history of the synclinal trough which 

forms the basin of lake Superior. The relations and likeness of the 

Penokee and the Aniinikie series have been repeated at length as showing the breadth of the "geological basin in which the deposition of like 

rocks was taking place simultaneously. The equivalency here shown 

is a long step in understanding the equivalency of other rocks in the 

lake Superior basin.

SUCCESSION AND EQUIVALENTS OF THE MARQUETTE DISTRICT SERIES.

la the Marquette district, as the succession has already been discussed, it need here be only briefly repeated. It is as follows: At the 

base is the Archean gneiss-granite-schist complex. In ascending order 

follow the Lower and Upper Marquette, having the lithological characters and relations above described.

Much work remains to be done in this district which has been studied so closely. From present knowledge it is not even definitely known
190 rRE-CAMHHIAX ROCKS OF NORTH AMERICA. [BULL. 88.

whether certain of the iron ranges, as for instance that of Teal lake, are 

Upper or Lower Marquette, .although it is very probable that the one 

mentioned belongs to the Upper. Also it is a serious question what 

part of the green schists and schist-conglomerates, some of which are cut 

by granite, belong in the Lower Marquette series. Eecent work appears to indicate that much if not all of this surface volcanic material 

belongs here, although it can not be asserted that surface volcanic material does not occur with the green schists of the Archean.

SUCCESSIONS AND EQUIVALENTS OF THE MENOMINEE AND FELCH MOUNTAIN DISTRICTS SERIES. .

Passing now to the Menominee and Felch mountain districts, information is less exact. It is, however, clear that in both of these areas 

the fundamental complex is found; that is, the granites and .gneisses 

associated with crystalline schists having the usual eruptive contacts. 

Above this complex, Pumpelly, with whom this whole subject has been 

discussed and who has great familiarity with the entire lake Superior 

region, suggests as exceedingly probable that in the Felch mountain 

iron-bearing series only the equivalent of the Lower Marquette occurs, 

the upper series, if it once existed, having been removed by erosion; 

while in the Menominee district both representatives of the Lower and 

Upper Marquette are present. The Menominee proper that is, that 

part of the area which includes the Chapin, Ludington, and Norway 

mines, those in which a cherty limestone is found are Lower Marquette, Avhile the western district, including such mines as the Commonwealth, Florence, and many others occurring in the upper black 

slate, are Upper Marquette. That between these two is a probable 

unconformity has already been shown.

EQUIVALENTS OF THE BLACK RIVER FALLS SERIES.

The Black river falls iron-bearing schists of Wisconsin have not such 

observable structural relations as to enable one certainly to determine 

their position. They arc, however, thoroughly crystalline schists, and 

are in vertical attitude. On these grounds they are provisionally 

placed as the equivalent of the Lower Marquette.

SUCCESSION AND EQUIVALENTS OF WESTERN ONTARIO AND NORTHEASTERN MINNESOTA

SERIES.

Combining the work of Dawson and Lawson about Kainy lake and the 

lake of the Woods, Smyth about Steep Itock lake, the Winchells and 

Irving in northeastern Minnesota, the succession appears to be granitegneiss-schist (Coutchiching"?) complex, unconformity, Keewatin, unconformity, Auimikie, unconformity, Keweenawan. There are also ir; 

this district great masses of granite-gneiss at least as late as the 

Keewatin. Included in the granite gneiss-schist basal complex are 

only such granite-gneisses as are more ancient than the oldest sedi-
VAN insB.] LAKE SUPERIOR REGION. 191

mentaries. This vast area has been too little studied to say definitely 

what part of the areas referred to Irving's mica-schist group, Wiuchell's 

Vermilion series, and Lawson's Coutcuidling belongs with the Basement 

Complex. It is equally difficult to say whether the Keewatin of Lawson and Winchell does not comprise more than one series. It is 

Lawson's opinion that it- does and that the physical break described 

as occurring iu the clastic series on the south shore exists between 

the Upper and Lower Keewatin. Our knowledge of this part of the 

lake Superior region is not sufficiently advanced to outline with 

any accuracy the areas which are to be referred to these main 

divisions. It is, however, tolerably clear that in this part of the region 

there are the same great subdivisions of the pre-Cambrian rocks as 

elsewhere; that a part of what has ordinarily been called Laurentian 

will be included in the Basement Complex; that a part of Irving's niicaschist group, Lawson's Coutchiching, and the Profs. Winchell's Vermilion also falls within this complex. It is further probable that a part 

of the Keewatin is the equivalent of the Lower Marquette, Lower Menominee, and equivalent series. It is possible that other parts of the 

series which have been designated Keewatin belong rather with, the 

Animikie. If, however, the break at the base of the Animikie is higher 

than that above the Vermilion, Hunter's island, and Kaministiquia ironbearing series, and the latter break belongs within the Keewatin, as 

now known, this group will need to be subdivided into two series, and 

the succession will thus be expanded at this point, into Lower Keewatiu, 

unconformity, and Upper Keewatin.

NOMENCLATURE.

There still remains the question of nomenclature. In Chapter vui, 

the major taxonomy of the' pre-Cambrian is discussed and reasons 

are given for including under the term Algonkiau all the preCambrian elastics, for confining the ternrArchean to the inferior crystalline complex, for restricting the term Laurentian to the coarser 

grained light colored granite-gneiss part of this complex, and for proposing for the dark colored fine grained schistose part of this complex 

the term Mareniscan. These reasons will not be repeated here, but the 

terms with these definitions will be applied to the rock successions of 

different districts of the lake Superior region. This will serve to illustrate the usage of these terms and at the same time will be a test of 

the propriety of the usages proposed, since the lake Superior region is 

the one in America about which most has been written and which furnishes the fullest pre-Cambrian column.

Belonging to the Archean on the south shore are the Southern Complex 

of the Penokee districts, the fundamental complex of the Marquette and 

Menominee districts, and a great expanse of rocks in northern Wisconsin. 

This complex is more largely of the Laurentian gneiss than of the 

Mareniscan schists. Between the two are often the peculiar gradations
192 FEE-CAMBRIAN ROCKS OF NORTH AMERICA. [B0JX.86.

described which are-taken to indicate the intrusive character of the 

granite-gneiss. Between the Archeau and the Algonkian, as indicated 

by evidence fully given in another place, there is a great unconformity.

On the north shore Smyth finds decisive evidence of a thoroughly 

crystalline fundamental complex below the lowest elastics at Steep Bock 

lake. As has been seen, evidence pointing in this same direction is to 

be found in the reports of Logan, Dawsou (Sir William), Selwyu, Bell, 

Macfaiiane, Herrick, and Lawson, although several of these authors do 

not reach this conclusion. The difficult and uncertain point in this 

connection is in reference to the Coutchiclimg of Lawson or the Vermilion of Profs. Wmchell. If, as believed by Lawsou, there is a great 

time break between the Keewatin and Coutchiching and if the 

Coutchiching is found to be older than any of the elastics, it belongs 

to the fundamental complex and the term Coutchiching has priority 

over Mareniscan, proposed for the dark colored, fine grained schistose 

part of the Archeau. This is the outcome which-seems to the writer, 

according to present published evidence, to be most likely; but it must 

be stated that this impression does not accord with Lawsou's opinion, 

Avho regards the Ooutchichiug as a sedimentary series more nearly connected with the Keewatin than with the Archeau, nor with the Profs. 

Winchell, who regard the equivalent Vermilion as but a more metamorphosed doAvnward extension of the Keewatin.

In restricting the word Laureutian to the granite-gneiss of the 

Archeau, much of what has heretofore been denominated Laurentian 

will be excluded. This usage will throw out all of the-granite-gneisses 

of an age later than the elastics, and therefore much of the granitegneiss which Lawson has called Laurentian. It must be recognized 

that about the lake Superior region there are granite-gneisses of various ages. This is more evident in the main granite-gneiss areas than 

elsewhere, for not infrequently intruding them are other large bosses 

of granite or gneiss, which, with the earlier granite-gneiss, may -have 

again been cut by still later material of the same kind. It is believed 

by sOme that there are in the lake Superior region granite-gneisses of at 

at least four different ages. It will not do to conclude that any certain 

granite-gneiss is Archeau unless its structural relations to the Algonkian elastics are determined. However, the granite-gneisses which 

belong to the Archeau on the south shore are pegmatized through and 

through and banded and contorted in the most intricate manner. 

Their constituent minerals show that they have undergone repeated 

dynamic movements. They are cut by eruptives of many kinds and of 

different ages, Many of the basic eruptives are so ancient that they 

themselves have become schistose and have passed over into hornblende-gneisses and similar rocks, which now are seen as dark colored 

intersecting or parallel layers in the pink granite-gneiss. This intricate complex of granite, gneiss,'and schist, which has been subjected 

to repeated dynamic movements in various directions, is very different
TAN HJBB.] LAKE SUPERIOR REGION. 193

from the somewhat regular, little altered granite-gneiss which acts as 

a subsequent intrusive.

The early Canadian geologists used the term Huronian to cover all the 

fine grained schistose and clastic rocks between the Keweenawan or Upper Copper-bearing rocks and the Laurentian. The same is true of many 

of the American geologists. It is clear that the fine grained crystalline 

schists which constitute a part of the Archean can not here be included. 

Huronian can include only that part of the Algonkian between the Keweenawan and Archean, and, as has been seen, this Huronian is separable into two uncomformable series. On the part of the Canadian 

geologists of late there has been a tendency to restrict this term to the 

lower series, as shown by the exclusion of the Animikie from the Huronian, but if this is done the greater part of the Original Huronian 

must itself be excluded from the Huronian. Upon the other hand, Irving and the Profs. Winchell have advocated restricting Huronian to the 

upper series alone. The recognition of a general stratigraphical break 

in the rocks heretofore included by most authorities in the Huronian 

leads to the natural suggestion that for the superior division Upper 

Huronian shall be used, and for the inferior Lower Huronian. The fact 

that it has been recently maintained that in the Original Huronian area 

itself both of these series exist but renders this suggestion more appropriate. Further in favor of this position is its conservative character, although it is recognized that the rules of good nomenclature 

point rather to the restriction of Huronian to the upper or lower 

series. ' If restricted to one it should clearly be the upper, for it is certain that the greater part of sediments of the Original Huronian mapped 

in detail here belongs. Hence, as advocated by Alex. Winchell, is 

placed as an alternative to Lower Huronian in the following tabulation 

Lawson's term Keewatin. This term was first defined to cover a series 

of elastics with some crystalline schists about the lake of the Woods. It 

was later more clearly defined and restricted to the unmistakable elastics and altered volcanics about Kainy lake. By the Profs. Winchell it 

was applied to the Vermilion lake iron-bearing series, which was believed by them to be the equivalent of the Rainy lake Keewatin. In 

many respects the greater part of these series is like the Lower Marquette, Felch mountain, Lower Menominee, Hunters island, and Lower 

Karninistiquia series. If this supposed equivalence were demonstrated 

it would be preferable to adopt this term to cover all the series included 

under the Lower Huronian. -It is, however, by no means clear that the 

Keewatin will not prove to be a complex series, just as have the Marquette and Vermilion lake rocks, consequently it is only tentatively 

placed in the general column. One other term has been proposed for 

this place, Marquettian; but this term is objectionable because as used: 

it included both Upper and Lower Marquette.

Lawson has proposed the term Ontarian to cover the Keewatin and 

Coutchiching. It appears to us that the purposes of geology are betBull.. 86 la ' '
194 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [B0u,.8G.

ter subserved by using the term Algonkian to cover all the clastic 

series between the Fundamental Complex and Cambrian, and to retain 

Archean as a term of coordinate value with this to cover the basal complex. If it shall turn out that the writer is correct as to the position 

of the Coutchiching, the base of the Lower Huronian, not the base of 

the Coutchiching, is the important horizon to mark. More evidence is 

desirable for the application of stratigraphical methods to the prominent structure of the Coutchiching, since, in many respects this structure has the characters of an induced one. Lawson recognizes a true 

physical break at the base of the Keewatin, not at the base of the 

Coutchiching. The break between the Coutchiching and the granitegneiss is one which is also found between the granite-gneiss and Keewatin. It is not a structural horizon^ but an eruptive contact. Upon 

the other hand, a great mass of evidence goes to show that there is at 

the base of the Keewatin a persistent structural plane which is recognizable throughout the lake Superior region.

Selwyn and ST. H. Winchell maintain that the Keweenawan and 

Animikie are properly Cambrian. Whether the term Cambrian shall 

be so extended downward as to cover two great unconformities and 

two additional rock series of very great thickness is, purely a matter of 

policy and of nomenclature, which is more fully discussed in another 

place. While it is of primary importance that an agreement shall be 

reached as to the actual rock successions in the lake Superior region, 

it is but a secondary matter as to the names which shall be applied to 

them. That fossils are found in the Huronian is not sufficient reason 

for extending the Cambrian downward indefinitely. That the evidences of abundant life are here found has been long known. Many 

of the thick beds of slates heretofore called Huronian, on the south 

shore of lake Superior, not only contain graphitic material, but a considerable percentage of hydrocarbons, not infrequently becoming graphitic or carbonaceous schists. In the Animikie, on the north shore of 

lake Superior, Ingall finds abundant carbon, and it is said that in 

certain mines and openings rock gas forms in -considerable amount. 

Also small quantities of rock may even be Obtained which will burn. 

These substances must result from the ordinary processes which produced rock gas and coal in the rocks of far later age. Also the great 

beds of iron carbonate are, to many, evidence of abundant life. In the 

Sioux quartzites one generally accepted fossil has been discovered by 

N. H. Winchell. A discovery of a fossil has been announced by Selwyn 

as occurring in the Animikie. It is a hope that in the future numerous 

other fossils will be found in this series, so that we may have the assistance of paleontology in lake Superior stratigraphy. Until, however, 

a fauna is known in these regions which is distinctly Cambrian, the 

discovery of life or of certain fossils in the Keweenawan and Huronian 

rocks is wholly insufficient evidence for placing them with the Cambrian.

We then have in the lake Superior region the following successions 

and correlations for the pre-Cambrian rocks:
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Upper Vermilion.

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196 PKK-OAMBRIAN ROCKS OF NORTH AMERICA. [BULL.86.

LAKE SUPERIOR BASIN.

The synclinal structure of the formations about lake Superior was 

noted as early as 1847 by Logan in his remarkably accurate general 

account of the lake Superior region. His five general formations were 

found to recur in reverse order on both sides of the lake, dipping to the 

center. Eogers and Agassiz, in 1848 and 1850, maintained that the 

shores of the lake are due to dikes. Owen, in 1851, in his studies north 

and south of the west part of the lake, saw that the formations occur 

in reverse order, and reached independently the same conclusion as did 

Logan. Bigsby and Whitney followed Logan and Owen in describing 

the lake Superior basin as synclinal. The next exact contributions to 

the structure of the lake Superior synclinal were by Sweet and Irving, 

who found it to continue to the southwestward in Wisconsin and Minnesota, the rocks adjacent to the shore on the south side of the west 

end of the lake being on the north side of the synclinal basin. Sweet, 

in 1876, spoke of the lake Superior synclinal as over 300 miles in length 

and 30 to 50 miles in width. That the lake Superior formations are 

not only a synclinal in an east and west direction, the rocks dipping 

respectively from the north shore south and the south shore north, but 

that it is a basin in the exact sense of the term, the rocks on the east 

shore dipping to the west, while the western termination of the synclinal 

in Minnesota plunges to the east .or northeast, was shown by Irving. 

This author went further and also showed that the major bays of the 

lake are due either to faults or subordinate flexures within the Keweenawan. The basin is clearly a product of Keweenawan time. Chamberlin suggests that it began early in the Keweenawan. The Upper 

Hurouian series partakes in several districts in large measure of the 

basin structure. This is apparent from the fact that the Huronian of

the Penokee and Animikie series was so long regarded as conformable

with the Keweenawan. It lias been seen that there is between these 

series a great unconformity, although not one so vast as the other 

physical breaks about the lake. As a consequence of this the Upper 

Huronian series corresponds only locally with the synclinal structure, 

and chiefly about the west half of the lake. The structures of the Lower 

Huronian and Archean have no reference to that of the lake Superior 

basin.

CONCLUSION.

It appears that in the lake Superior region is a general succession 

which may be recognized, and that there is really a much greater 

degree of harmony than has been thought in the conclusions which the 

various writers have held most steadfastly as to the lake Superior 

stratigraphy. From the base up ward it is as follows: Archean, including Laurentiaii granite and gneiss, the origin of which is largely unknown, but which were certainly in their present condition earlier than 

the formation of the Lower Huronian j unconformity} Lower Huroniau
VANHISE.] LAKE SUPERIOR REGION. 197

(a closely folded seinicrystalline series); unconformity; Upper Huronian (a gently folded and plainly clastic series, although indurated 

by cementation and metasoniatic changes); unconformity; completely 

unaltered Keweenawan; unconformity; lake Superior sandstone. In 

addition to the above are great masses of eruptive rocks in all the series, 

both basic and acidic, including granite-gneiss, gabbro, porphyry, diabase,, etc.

I can not close without comparing this succession of lake Superior 

formations with that given byLoganin his remarkable paper published 

in 1847. It is as follows: " (1) Granite and syenite; (2) gneiss; (3) 

chloritic and partially talcose and conglomeratic slates; (4) bluish 

slates or shales interstratified with trap; (5) sandstones, limestones, 

indurated marls, and conglomerates, interstratified with trap." Between 1, 2, 3, and 4, 5 there was said to be an unconformity. The 

granite, syenite, and gneiss are Archean; the chloritic and partly talcose and conglomeratic slates, Lower Huronian; the bluish slates or 

shales interstratified with trap. Upper Huronian; and the sandstones, 

limestones, indurated marls, and conglomerates interstratified with 

trap, Keweenawan. Of course, Logan at that time did not appreciate 

all the structural relations which obtain between these various series, 

although the greatest of the unconformities was discovered, nor did he 

suppose that they are all pre-Carnbrian, and in his mapping in 1863,1 

and 2 are placed together as Lower Laurentian, and 4 and 5 together as 

a part of the Quebec group above the Potsdam; yet that he appreciated 

that in this region there are five fundamentally different kinds of rock, 

that he gave an accurate characterization of the Keweenaw series, comprehending that it is one of great thickness, not less than 10,000 or 

12,000 feet, and that this series rests unconformably upon the granite 

and gneiss, can not be too highly spoken of. Not only was this paper 

the first announcement of all of the above great conclusions, but it gave 

the first mention, as has been seen, of the synclinal structure of lake 

Superior.

Looking toward the future as to the possible modifications of this 

arrangement by further work, the point of greatest doubt lies as to 

whether the unconformities here recognized as universal in the lake 

Superior region are really so. Is it not possible that the unconformity 

at the base of the Animikie is at a different position from that between 

the Penokee proper and the Cherty Limestone, and may not these be 

different horizons from that between the Upper and Lower Marquette? 

May not the break above the Lower Marquette be at a different position from that above the Lower Vermilion. These questions can not 

be positively answered in the negative, although all the evidence at 

hand bears strongly in this direction. It may be found in the lake 

Superior basin, so extensive in area, that while the folding and erosion 

producing an unconformity in one part was occurring, at some 

other distant part deposition was going on. In all probability this is
198 PRE-CAMBRIAN ROCKS OP NORTH AMERICA. ' [BOLL.86.

to some extent true. That the rocks in the different districts referred 

to these periods have the same absolute duration would hardly be expected. Sedimentation in the series correlated probably continued 

longer in certain parts of the region than in others. A break even if 

as widespread as believed probably did not begin nor end everywhere 

at the same time; and certainly it would be true, after a certain movement and erosion had ended, as the sea began to encroach, that sedimentation would begin in one district before it reached another. So 

that if these correlati ons are correct and the breaks really general, as 

is believed, it does not follow that the periods opened or closed simultaneously, but that they stand in a general way as equivalent. The 

equivalency advocated may be much more strongly asserted of the districts immediately adjacent to lake Superior than of the more remote 

districts.

The further question arises, whether as work continues new breaks of 

considerable magnitude, not now recognized, will be found. This is not 

improbable. In fact, there is already some indication of such a break, 

although not now capable of being proved at any point. Does the series 

of great conglomerates which are placed at the base of the Upper Huronian, the debris being derived mostly from the Lower Huronian, grade 

conformably upward into the Animikie, or is there here a considerable 

additional break? It is by no means certain that the truth is not with 

the latter alternative, for the conglomerates certainly seem to have suffered more intense dynamic action than the adjacent Ammikie. Their 

thickness is great, and it may well be that in the Thunder bay district 

will be found a considerable break which in a part at least of the lake 

Superior region will subdivide the Upper Huronian.

Also as a problem for the future is the real nature of the Archean 

schists. Are they clastic or igneous in origin! Are they, as has been 

supposed, a real fundamental complex, or will this be subdivided upon 

a structural basis? A few years ago all below the pre-Cambrian was a 

fundamental complex. Will not the future find our present funda. 

mental complex further divisible and the real fundamental complex at 

a still lower horizon?

Accepting the general stratigraphy as given above, how far will it be 

possible to correlate the individual formations of the series? How far 

are the Quartz-Slate member, the Iron-bearing member, and the Upper Slate member of the Penokee series equivalent to those of the Animikie? When, as in this case, three like formations of great thickness 

are found in the same order, and the two series as wholes bear identical 

relations to underlying and overlying series, the correlation may perhaps be made with a considerable degree of probability, and later closer 

work rather leads to the conclusion that much will be accomplished in 

the direction of correlating formations; that is, several of the series may 

be divided into two or three or more members, which may with a considerable degree of probability be correlated with equivalent members
VANHISE.] LAKE SUPERIOR REGION. 199

in other- districts, but that it will bet possible to subdivide these various 

series into fifteen or twenty or more members, as was done by the early 

authors, and to correlate these small divisions with each other throughout the lako Superior region, there is not the least probability.

While perhaps more has been done in pre-Cambrian stratigraphy in 

the lake Superior region than in any other region in America, this very 

fact opens before us numerous and difficult problems.

NOTES.

1 Notes on the Geography and Geology of Lake Superior, John J. Bigsby. .Quart. 

Jour. Sci., Lit. and Arts, vol. xvm, pp. 1-34,222-269; with map.

3 Outlines of the Geology of Lake Superior, H. W. Bayfield. Trans. Literary and 

Historical Soc. of Quebec, vol. i, 1829, pp. 1-43.

3 On the Junction of the Transition and Primary Rocks of Canada and Labrador, 

Capt. Bayfield. Quart. Jour. Geol. Soc., London, vol. 1,1845, pp. 450-459.

4 On the Geology and Economic Minerals of Lake Superior, W. E. Logan. Rept. 

of Prog. Geol. Survey of Canada for 1846-'47, pp. 8-34.

6 On the Geology of the Kaministiquia and Michipicoten Rivers, Alexander Murray. Ibid., pp. 47-57.

6 On the Age of the Copper-Bearing Rocks of Lakes Superior and Huron, and 

various facts relating to the Physical Structure of Canada, W. E. Logan. Rept. of 

British Assn. for the Adv. Sci., 1851, 21st meeting, pp. 59-62, Trans.; see also, On 

the Age of the Copper-Bearing Rocks of Lakes Superior and Huron, William E. 

Logan. Am. Jour. Sci., 2d ser., vol. xiv, 1852, pp. 224-229.

7 On the Geology of the Lake of the Woods, South Hudson s Bay, Dr. J. J. Bigsby. 

Quart. Jour. Geol. Soc., London, vol. vm, 1852, pp. 400-406. With a geological map 

of the Lake of the Woodj.

8 On the Physical Geography, Geology, and Commercial Resources of Lake Superior, John J. Bigsby. Edinburgh New Phil. Jour., vol. LIII, 1852, pp. 55-62.

9 On the Geology of Rainy Lake, South Hndsons Bay, Dr. J. J. Bigsby. Quart. 

Jour. Geol. Soc., London, vol. x, 1854, pp. 215-222. With a geological map of Rainy 

Lake.

10 On the Geological Structure and Mineral Deposits of the Promontory of Mamainse, Lake Superior, John W. Dawsoii. Can. Nat. and Geol.,vol. n, 1857, pp. 1-12. 

With a section.

11 Report of Progress of the Geological Survey of Canada from its Commencement 

to 1863, W. E. Logan; pp. 983. With an atlas.

12 On the Laurentiau, Huronian, and Upper Copper-Bearing Rocks of Lake Superior, Thomas Macfarlane. Rept. of Prog. Geol. Survey of Canada for the year 

1863 to 1866, pp. 115-164.

13 On the Geological Formations of Lake Superior, Thomas Macfarlane. Can. 

Nat., 2nd ser., vol. in, 1866-'68, pp. 177-202, 241-257.

14 On the Geology and Silver Ore of Woods Location, Thunder Cape, Lake Superior, 

Thomas Macfarlane. Can. Nat., 2d series, vol. iv, pp. 37-48, 459-463; with a map.

16 On the Geology of the Northwest Coast of Lake Superior and the Nipigon District, Robert Bell. Rept. of Prog. Geol. Survey of Canada from 1866 to 1869, pp. 313- 

364; with a topographical sketch-map.

16 Report on the Country North of Lake Superior, between the Nipigon and Michipicoten Rivers, Robert Bell. Rept. of Prog. Geol. Survey of Canada for 1870-71, pp. 

322-351.

1T Report on the Country between Lake Superior and the Albany" River, Robert 

Bell. Rept. of Prog. Geol. Survey of Canada for 1871-'72, pp. 101-114.

18 Notes of a Geological Reconnaissance .from Lake Superior to Fort Carry, A. R. C. 

Selwyn. Rept. of Prog. Geol. Survey of Canada for 1872-'73, pp. 8-18.
"Y

200 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

19 On the Country between Lake Superior and Winnipeg, Robert Bell. Ibid., pp. 

87-111.

20 Tke Geognostical History of the Metals, T. Sterry Hunt. Trans. Am. Inst. Min. 

Eng., vol. i, pp. 331-345; vol. n, pp. 58-59.

31 On the Country between Red River and the South Saskatchewan, with Notes on 

the Geology of the Region between Lake Superior and Red River, Robert Bell. Rept. 

of Prog. Geol. Survey of Canada for 1873-74, pp. 66-90.

32 Report' on the Geology and Resources of the Region in the Vicinity of the Fortyninth Parallel, from the Lake of the Woods to the Rocky Mountains, George Mercer 

Dawson, pp. 387; with a geological map.

23 The Mineral Region of Lake Superior, Robert Bell. Can. Nat. and Geol., 2d ser., 

vol. vu, 1875, pp. 49-51.

24 On the Country west of Lakes Manitoba and Winnipegosis, with Notes on the 

the Geology of Lake Winnipeg, Robert Bell. Rept. of Prog. Geol. Survey of Canada 

for 1874-'75, pp. 24-56.

28 Report on an Exploration in 1875 between James Bay and Lakes Superior and 

Huron, Robert Bell. Rept. of Prog. Geol. Survey of Canada for the year 1875-'76, pp. 

294-342.

2S Report on Geological Researches North of Lake Huron and East of Lake Superior, Robert Bell. Rept. of Prog. Geol. Survey of Canada for 1876-'77, pp. 213-220. 

 27 Remarks on Canadian Stratigraphy, Thomas Macfarlane. Can. Nat., 2d ser., 

vol. ix, 1879, pp. 91-102.

28 Report on the Geology of the Lake of the Woods and Adjacent Country, Robert 

Bell. Rept. of Prog. Geol. and Nat. Hist. Survey of Canada for the years 1880-'81-'82, 

pp. 11-15 C; with a map.

29 On the Geology of Lake Superior, A. R. C. Selwyn. Trans. Royal Soc. Canada, 

vol. I, sec. 4, 1883, pp. 117-122.

30 Age of the Rocks of the Northern Shore of Lake Superior, A. R. C. Selwyn. 

Science, vol. i, p. 11. See also the Copper-Bearing Rocks of Lake Superior, A. R. C. 

Selwyn. Ibid., p. 221.

al Notes on Observations, 1883, on the Geology of the North Shore of Lake Superior, A. R. C. Selwyn. Trans. Royal Soc., Canada, vol. u, sec. 4, p. 245.

32 Report on the Geology of the Lake of the Woods Region, with Special Reference 

to the Keewatin (Huronian?) Belt of Archean Rocks, A. C. Lawson. Ann. Rept. 

Geol. and Nat. Hist. Survey of Canada for 1885, vol. i (new series), pp. 5-151 CC; 

with a map.

33 Geology and Lithology of Michipicoten Bay, C. L. Herrick, W. G. Tight, and H. 

L. Jones. Bull. Denison Univ., vol. n, pp. 120-144; with 3 plates.

34 The Correlation of the Animikie and Huronian Rocks of Lake Superior, Peter 

McKellar. Proc. and Trans. Royal Soc., Canada, for 1887, vol. V, sec. 4, 1887, pp. 

63-73.

36 Report on the Geology of the Rainy Lake Region, A. C. Lawson. Ann. Rept. 

Geol. and Nat. Hist. Survey of Canada for 1887-;88, vol. in (new series), pp. 1-196 

P; with 2 maps and 8 plates. See also the Archean Geology of the Region Northwest of Lake Superior, A. C. Lawftm. Etudes sur les Schistes Cristallins, International Geol. Congress, London, 1888, pp. 66-88; Geology of the Rainy Lake Region, 

with remarks on the classification of the Crystalline Rocks West of Lake Superior. 

Preliminary note. Am. Jour. Sci., 3d ser., vol. xxxm, 1887, pp. 473-480.

36 Report on Mines and Mining on Lake Superior, E. D. Ingall. Ann. Rept. Geol. 

and Nat. Hist. Survey of Canada for 1887-'88, vol. MI (new series), pp. 1-131 H; 

with 2 maps and 13 plates.

37 Tracks of Organic Origin in Rocks of the Animikie Group, A. R. C. Selwyn. 

Am. Jour. Sci., 3d ser., vol. xxxix, 1890, pp. 145-147.

38 The Internal Relations and Taxonomy of the Archean of Central Canada. Andrew C. Lawson. Bull., Geol. Soc. of America, vol. i, pp. 175-194.
VANHISE.] LAKE SUPERIOR REGION. 201

39 Geology of Ontario with special reference to economic minerals. Robert Bell. 

Report of the Royal Commission on the Mineral Resources of Ontario, Toronto, 

1890, pp. 1-70.

40 Lake Superior Stratigraphy, Andrew C. Lawson. Am. Geol., vol. vn, 1891, 

pp. 320-327.

41 The Structural Geology of Steep Rock Lake, Ontario, Henry Lloyd Smyth. Am. 

Jour. Sci., 3d ser., vol. XLII, 1891, pp. 317-331.

42 Narrative Journal of Travels through the Northwestern Regions of the United 

States, extending from Detroit through the Great Chain of American Lakes to the 

Sources of the Mississippi River, Henry R. Schoolcraft. Albany, 1821; pp. 419 with 

map.

43 Account of a Journey to the Coteau des Prairies, with a description of the Red 

Pipe Stone Quarry and Granite Bowlders found there, George Catlin. Am. Jour. Sci., 

1st ser., vol. xxxvm, pp. 138-146.

44 Geology of Porter's Island and Copper Harbor, John Locke. Trans. Am. Phil. 

Soc., vol. ix, 1844, pp. 311-312; with maps. 

46 Keporfc of Walter Cunningham, late Mineral Agent on Lake Superior, January 8.

1845. Senate Docs., 2d sess. 28th Cong., 1844-'45, vol. vii, No. 98, pp. 5

46 Mineral Report, George N. Sanders. Ibid., No. 117, pp. 3-9.

47 Report of J. B. Campbell. Ibid., vol. XI, No. 175, pp. 4-8.

48 Report of George N. Sanders. Ibid., pp. 8-14.

49 Report of A. B. Gray. Ibid., pp. 15-22.

60 Report of A. B. Gray on Mineral Lands of Lake Superior. Executive Docs., 1st 

BOSS. 29th Cong., 1845-'46, vol. vn, No. 211, pp. 23; with map.

fil Mineralogy and Geology of Lake Superior, H. D. Rogers. Proc. Best. Soc. Nat. 

Hist., vol. H, 1846, pp. 124-125.

62 Preliminary Report, containing Outlines of the Progress of the Geological Survey 

of Wisconsin and Iowa, up to October 11,1847, David Dale Owen. Senate Docs., 1st 

seas. 30th Cong., 1847, vol. n, No. 2, pp. 160-174.

63 Report of Observations made in the Survey of the Upper Peninsula of Michigan, 

John Locke. Ibid., pp. 183-199.

64 Report of J. D. Whitney. Ibid., pp. 221-230.

65 Report of a Geological Reconnaissance of the Chippewa Land District of Wisconsin, etc., David D. Owen. Ibid., vol. vii, No. 57, pp. 72.

66 Report of J. G. Norwood. Ibid., pp. 73-134.

67 On the Origin of the Actual Outlines of Lake Superior (Discussion), William B. 

Rogers. Proc. Am. Assoc. Adv. Sci., 1848, 1st meeting, pp. 79-80.

6S Report of J. D. Whitney. Senate Docs., 2cl sess. 30th Cong., 1848-M9, vol, n, No. 

2, pp. 154-159.

69 Report of J. W. Foster, Ibid., pp. 159-163.

GO On the Geological Structure of Keweenaw Point, Charles T. Jackson. Proc. Am. 

Assoc. Adv. Sci., 1849, 2d meeting, pp. 288-301.

61 The Lake Superior Copper and Iron District, J. D. Whitney. Proc. Bost. Soc. 

Nat. Hist., vol. m, 1849, pp. 210-212.

62 The Outlines of Lake Superior, Louis Agassiz. Lake Superior: Its Physical Character, Vegetation, and Animals, compared with those of other and similar regions, 

by Louis Agassiz and J. Elliott Cabot, pp. 417-426. See, also, Proc. Am. Assoc. Adv. 

Sci., 1848, 1st meeting, p. 79.

63 Report on the Geological and Mineralogical Survey of the Mineral Lands of the 

United States in the State of Michigan, Charles T. Jackson. Senate Docs., 1st sess. 

31st Cong., 1849-J50, vol. in, No. 1, pp. 371-935; with 14 maps. Contains reports by 

Messrs. Jackson, Dickenson, Mclntyre, Barnes, Locke, Foster and Whitney, Whitney, 

Gibbs, Whitney, Jr., Hill and Foster, Foster, Burt, Hubbard.

«4 Ibid., pp. 371-503.

66 United States Geological Survey of Public Lands in Michigan. Field Notes, John 

Locke. Ibid., pp. 572-587.
202 PKE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

6ti Synopsis of the Explorations of the Geological Corps in the Lake Superior Land 

District in the Northern Peninsula of Michigan, J. W. Foster and J. D. Whit.ney. 

Ibid., pp. 605,626, with 4 maps.

67 Notes on the Topography, Soil, Geology, etc., of the District between Portage 

Lake and the Ontonagon, J. D. Whitney. Ibid., pp. 649-666. Report of J. D. Whitney. Ibid., pp. 705-711.

68 Report of J. W. Foster. Ibid., pp. 766-772. Notes on the Geology and Topography of the Country Adjacent to Lakes Superior and Michigan, in the Chippewa 

Land District, J. W. Foster. Ibid., pp. 773-786.

69 Topography and Geology of the Survey with reference to Mines and Minerals, of 

a district of township lines south of Lake Superior, William A. Burt. Ibid., pp. 

811-832. With a geological map opposite i>. 880.

70 General Observations upon the Geology and Topography of the District south 

of Lake Superior, subdivided in 1845 under direction of Douglass Houghton, Deputy 

Surveyor, Bela Hubbard. Ibid., pp. 833-842.

71 Geological Report of the Survey " with reference to Mines and Minerals," of a 

district of township lines in the State of Michigan, in the year 1846, and tabular 

statement of specimens collected. Ibid., pp. 842-882, with a geological map.

72 Report on the Geology and Topography of the Lake Superior Land District, 

part 1, Copper Lands, J. W. Foster and J. D. Whitney. Executive Docs., 1st sess. 

31st Cong., 1849-'50, vol. ix, No. 69, p. 244, with map.

73 Report on the Geology and Topography of the Lake Superior Land District, 

part 2, the Iron Region, J. W. Foster and J. D. Whitney. Senate Docs., special 

sess. 32d Cong., 1851, vol. in, No. 4, 406 pp., with maps. See also Apercu de 

Pensemble des Terrains Siluriens du Lac Superieur, by J. W. Foster and J. D. Whitney. Bull. Soc. G6ol. France, 1850 (2), pp. 89-100.

74 On the Azoic System, as developed in the Lake Superior Land District, J. W. 

Foster and J. D. Whitney. Proc. Am. Assoc. Adv. Sci., 1851, 5th meeting, pp. 4-7.

76 On the Age of the Sandstone of Lake Superior, with a Description of the Phenomena of the Association of Igneous Rocks, J. W. Foster and J. D. Whitney. 

Ibid., pp. 22-38.

76 Abstract of an Introduction to the Final Report of the Geological Surveys made 

in Wisconsin, Iowa, and Minnesota, in the years 1847,1848,1849 and 1850, containing a Synopsis of the Geological Features of the Country, David D. Owen. Ibid., pp.

119-132.

77 On the Age, Character, and True Geological Position of the Lake Superior Red 

Sandstone Formation, David D. Owen. Report of a Geological Survey of Wisconsin, Iowa, and Minnesota, pp. 187-193.

78 Description of the Geology of Middle and Western Minnesota; including the 

country adjacent to the Northwest and part of the Southwest Shore of Lake Superior; illustrated by numerous general and local sections, woodcuts, and a map, 

J. G. Norwood. Ibid., pp. 209-418.

79 Description of part of Wisconsin South of Lake Superior, Charles Whittlesey. 

Ibid., pp. 419-470.

80 Local Details of Geological Sections on the St. Peters, Wisconsin, Mississippi, 

Baraboo, Snake, and Kettle rivers, B. F. Shumard. Ibid., pp. 475-522.

81 Geology, Mineralogy, and Topography of the Lands around Lake Superior, 

Charles T. Jackson. Senate Docs., 1st sess. 32d Cong., 1851-'52, vol. xi, pp. 232-244.

82 A Geological Map of the United States and the British Provinces of North America, with an Explanatory Text, Geological Sections, etc., Jules Marcou. Boston, 

1853, p. 92. See also "Re~ponse a la Lettre de MM. Foster et Whitney sur le Lac 

Superieur," Jules Marcou. Bull. Soc. Ge"ol., France, 2d series, vol. vin, pp. 101-105.

s3 The Metallic Wealth of the United States, J. D. Whitney. Philadelphia, 1854, 

Henry R. Schoolcraft. 510 pp.

 * Observations on the Geology and Mineralogy of the Region embracing the
VAN HISE.] LAKE SUPERIOR REGION. 203

Sources of the Mississippi River, and the Great Lake Basins, during the Expedition 

of 1820, Henry R. Schoolcroft, Summary Narrative of an Exploratory Expedition 

to the Sources of the Mississippi River, in 1820; Resumed and Completed by the Discovery of its Origin in Itasca Lake, in 1832, Henry R. Schoolcraft. Pages 303-362.

86 Remarks on Some Points Connected with the Geology of the North Shore of Lake 

Superior, J. D. Whitney. Proc. Am. Assoc. Adv. Sci., 1855,9th Meeting, pp. 204-209.

80 On the Occurrence of the Ores of Iron in the Azoic System, J. D. Whitney. Ibid., 

pp. 209-216.

CT Remarks on the Huronian and Laurentian Systems of the Canada Geological 

Survey, J. D. Whitney. Am. Jour. Sci., 2d ser., vol. xxiu, pp. 305-314.

88 Age of the Lake Superior Sandstone, Charles T.Jackson. Proc.'Bost. Soc. Nat. 

Hist., 1860, vol. vn, pp. 396-398.

89 Age of the Sandstone, William B. Rogers. Ibid., pp. 394,395.

90 Some Contributions to a knowledge of the constitution of the Copper Range 

of Lake Superior, C. P. Williams and J. F. Blandy. Am. Jour. Sci., 2d ser., vol. xxxiv, 

pp.112-120.

91 On the Iron Ores of Marqnette, Michigan, J. P. Kimball, Ibid., vol. XL, pp. 290-

303.

92 On the Position of the Sandstone of the Southern Slope of a portion of Keweenaw 

Point, Lake Superior, Alexander Agassiz. Proc. Bost. Soc. Nat. Hist., vol. xi, 1867, 

pp. 244-246.

9:) Physical Geology of Lake Superior, Charles Whittlesey. Proc. Am. Assoc. Adv. 

Sci., 24th Meeting, 1875, part 2, pp. 60-72, with map.

P4 Notes on the Iron and Copper Districts of Lake»Su perior, M. E. Wadsworth. Bull. 

Mus. Comp. Zool. Harvard College, whole series, vol. vn; Geological series, vol. i, 

No. 1, pp. 157. See also by the same author, on the Origin of the Iron Ores of the 

Marquette District, Lake Superior. Proc. Bost. Soc. Nat. Hist., vol. xx, 1878-'80, 

pp. 470-479. On the Age of the Copper-bearing Rocks of Lake Superior (abstract); 

Proc. Am. Assoc. Adv. Sci., 29th Meeting, pp. 429-430. On the Relations of the 

" Keweenawan Series" to the Eastern Sandstone in the vicinity of Torch Lake, 

Michigan; Proc. Bost. Soc. Nat. His., vol. xxni, 1884-;88, pp. 172-180; Science, vol. 

I, pp. 248, 249, 307.

95 On a Supposed Fossil from the Copper-Bearing Rocks of Lake Superior, M. E. 

Wadsworth. Proc. Bost. Soc. Nat. Hist., vol. xxni, 1884-'88, pp. 208-212.

9*Third Annual Report of the Geological Survey of Michigan, Douglass Houghton. 

State of Michigan, House of Representatives, No. 8, pp. 1-33.

97 Foiirth Annual Report of the State Geologist, Douglass Houghton. Ibid., No. 27, 

pp. 184. See also Metalliferous Veins of the Northern Peninsula of Michigan, 

Douglass Houghton. Am. Jour. Sci., 1st ser., vol. XLI, 1841, pp. 183-186.

98 First Biennial Report of the Progress of the Geological Survey of Michigan, 

Alexander Winchell. Lansing, 1861, pp. 339.

99 Dievorsilurischen Gebilde der "ObernHalbiusel von Michigan " in Nord-Amerika, 

Hermann Credner. Zeits. dor Deutsch. Geol. Gesell., vol. xxi, 1869, ]pp. 516-554. 

See also Die Gliederung der eozoischen (vorsilurischen) Formationsgruppe NordAiuerikas, Hermann Credner. Zeits. fur die Gesamniten Naturwissenschafteu, Giebel, 

1868, vol. xxxn, pp. 353-405.

100 On the Age of the Copper-Bearing Rocks of* Lake Superior, T. B. Brooks and 

R. PurnpeHy. Am. Jour. Sci., 3rd ser., vol. in, 1872, pp. 428-432.

101 Iron-Bearing Rocks, T. B. Brooks. Geol. Survey of Michigan, vol. I, part 1, 

1869-'73, pp. 319, with maps.

IK Copper-Bearing Rocks, R. Pumpelly. Ibid., part 2, pp. 1-46, 62-94, with maps.

108 Copper-Bearing Rocks, A. R. Marvine. Ibid., part 2. pp. 47-61, J'5-140.

104 Paleozoic Rocks, Charles Rominger. Ibid., part 3, pp. 105.

10S Observations on the Ontonagon Silver Mining District and the Slate Quarries of 

Huron Bay, Charles Rominger. Geol. Survey of Michigan, vol. in, part 1, 1876, pp 

151-166.
204 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

106 Ou the Youngest Huronian Rocks South of Lake Superior, and the Age of the 

Copper-bearing Series, T. B. Brooks. Am. Jour. Sci., 3d ser., vol. xi, 1876, pp. 

206-211.

107 Classified list of Rocks observed in the Huronian Series south of Lake Superior, 

T. B. Brooks. Ibid., vol. xn, pp. 194-204.

108 Metasomatic Development of the Copper Bearing Rocks of Lake Superior, 

Raphael Pumpelly. Proc. Am. Acad. Arts and Sci., 1878, vol, xm, pp. 253-309.

109First Annual Report of the Commissioner of Mineral Statistics of the State of 

Michigan for 1877-'78, Charles E. Wright. Marquette, 1879, 229 pp.

110 Upper Peninsula, C. Rominger. Geological Survey of Michigan, vol. iv, pp. 

1-248, with a geological map.

111 Report of N. H. Winchell. 16th Ann. Rept. Geol. and Nat. Hist. Survey of 

Minnesota for 1887, pp. 13-129.

115 Report of Alexander Winchell. Ibid., pp. 133-391.

113 A Sketch of the Geology of the Marquette and Keweenawan District, M. E. 

Wadsworth. Along the South Shore of Lake Superior, by Julian Ralph. 1st edition, 1890, pp. 63-82.

»<Ibid., 2d edition, 1891, pp. 75-99.

116 On the Relations of the Eastern Sandstone of Keweenaw Point to the Lower 

Silurian Limestone, M. E. Wadsworth. Am. Jour. Sci., 3d eer., vol. XLII, 1891, pp. 

170-171 (communicated).

116 The South Trap Range of the Keweenawan Series, M. E. Wadsworth. Ibid., pp. 

417-419.

117 Geological Report on the Upper Peninsula of Michigan, exhibiting the progress 

of work from 1881 to 1884, C. Rominger.

This report was finished and transmitted to-the governing board of the Michigan 

Geological Survey several years ago, but as yet remains unpublished. A manuscript 

copy was kindly furnished us for our use, and from this the abstract is taken.

118 On Southern Wisconsin, including the iron, lead, and zinc districts, with an account of the Metamorphic and Primitive Rocks, James G. Percival. Ann. Rept. Geol. 

Survey of Wisconsin, 1856, pp. 111.

H9The Iron Ores of Wisconsin, Edward Daniels. Ann. Re*pt. Geol. Survey of Wisconsin for the year ending 1857, pp. 62.

110 The Penokee Iron Range, Increase A. Lapham. Trans. Wis. State Agr. Soc., vol.

V, 1858-59, pp,391-400, with map.

131 Geological Report of the State of Wisconsin, Jaines Hall. Report of the Superintendent of the Geological Survey (1861), exhibiting the progress of the work, pp. 52-

m Physical Geography and General Geology, Jaines Hall. Report on the Geological Survey of the State of Wisconsin, vol. I, pp. 1-72.

1S3 The Penokie Mineral Range, Wisconsin, Charles Whittlesey. Proc. Boat. Soc. 

Nat. Hist., vol. ix, 1863, pp. 235-244.

124 On the Age of the Quartzites, Schists, and Conglomerates of Sank County, Wisconsin, R. D. Irving. Am. Jour. Sci., 3d ser., vol. m, 1872, pp. 93-99.

126 Report on the Geological Survey of the Mineral Regions, John Murrish. Trans. 

Wis. Agr. Soc., l872-'73, pp. 469-494.

126 On the relations of the Sandstone, Conglomerates, and Limestone of Sauk County, 

Wisconsin, to each other and to the Azoic, James H. Eaton. Am. Jour. Sci., 3d ser., 

vol. v, pp. 444-447.

127 Note on the Age of the Metamorphic Rocks of Portland, Dodge County, Wisconsin, R. D. Irving. Ibid., pp. 282-286.

1M On some Points in the Geology of Northern Wisconsin, R. D. Irving. Trans. Wis. 

Acad. of Sci., vol. 11,1873-'74, pp. 107-119. See also on the Age of the Copper-bearing 

Rocks of Lake Superior, and on the Westward Continuation of the Lake Superior 

Synclinal. Am. Jour. Sci., 3d ser., vol. vm, 1874, pp. 46-56. Ann. Rept. of Progress 

and Results of the Wisconsin Geological Survey for 1876, pp. 17-25; Report of Progress and Results for the year 1874; Geol. of Wisconsin, vol. n, pp. 46-49.
VAN BISK.! LAKE SUPERIOR REGION. 205

i39Notes on the Geology of Northern Wisconsin, E. T. Sweet. Trans. Wis. Acad. of 

Sci., 1875-'76, vol. in, pp. 40-55.

130 Note on the Age of the Crystalline Rocks of Wisconsin, R. D. living. Am. Jour. 

Sci., 3rd ser., vol. xm, 1877, pp. 307-309.

131 Report of Progress and Results, for the year 1875, 0. W. Wight. Geol. of Wisconsin, vol. n, 1873-'77, pp. 67-89.

1W Geology of Eastern Wisconsin, T. C. Chamberlin. Ibid., pp. 93-405, with 3 

atlas maps.

13-< Geology of Central Wisconsin, R. D. Irving. Ibid., pp. 409-636, with 2 atlas 

maps.

134 On the Geology of Northern Wisconsin, R. D. Irving. Ann. Rept. Wisconsin 

Geol. Survey for the year 1877, pp. 17-25.

136 Report on the Eastern part of the Penokee Range, T. C. Chamberlin. Ibid., pp. 

25-29.

136 General Geology of the Lake Superior Region, R. D. Irving. Geol. of Wisconsin, vol. in, pp. 1-24. Geology of the Eastern Lake Superior District. Ibid., pp. 

51-238, with 6 atlas maps. Mineral Besources of Wisconsin. Trans. Am. Inst. Min.

Eng., vol. vni, 1880, pp. 478-508, with map. Note on the Stratigraphy of the Huroniaii 

Series of Northern Wisconsin, and on the Equivalency of the Huronian of the Marquette and Penokee Districts. Am. Jour. Sci., 3d ser., vol. xvn, 1879, pp. 393-398.

137 Huronian Series west of Penokee Gap, C. E. Wright. Geol. of Wisconsin, vol. 

in, pp. 241-301, with an atlas map.

138 Geology of the Western Lake Superior District, E0 T. Sweet. Ibid., pp. 303- 

362, with an atlas map.

139 Geology of the Upper St. Croix District, T. C. Chamberlin and Moses Strong. 

Ibid., pp. 363-428, with 2 atlas maps.

140 Geology of the Menominee Region, T. B. Brooks. Ibid., pp. 430-599, with 3 

atlas maps.

141 Geology of the Menominee Iron Region (Economic Resources, Lithology and 

Westerly and Southerly Extension), Charles E. Wright. Jbid., pp. 666-734.

142 The Quartzites of Barron and Chippewa counties, Moses Strong, E. T. Sweet, F. 

H. Brotherton, and T. C. Chamberlin, Geol. of Wisconsin, vol. iv, 1873-;79, pp. 573-581.

143 Geology of the Upper Flambeau valley, F. H. King. Ibid., pp.583-615.

144 Crystalline Rocks of the Wisconsin Valley, R. D. Irving andC. R. Van Hise. Ibid., 

pp.623-714.

146 General Geology (of Wisconsin), T. C. Chamberliu, Geol. of Wisconsin, vol. i, pp. 

3-300, with an atlas map.

14<5Lithology of Wisconsin, R. D. Irving. Ibid., pp. 340-361.

147 Transition from the Copper-bearing series to the Potsdam, L. C. Wooster, Am. 

Jour. Sci., 3d ser., vol. xxvn, pp. 463-465.

148 Mode of Deposition of the Iron Ores of the Menominee Range, Michigan, John 

Fulton. Trans. Am. Inst. Min. Eng., vol. xvr, pp. 525-536.

149 Report of the State Geologist on the Metalliferous Region bordering on Lake 

Superior, Henry H. Eames. St. Paul, 1866, pp. 21.

150 Geological Reconnaissance of the Northern, Middle and other Counties of Minnesota, Henry H. Eames. St. Paul, 1866, pp. 58.

151 Notes upon the Geology of some portions of Minnesota, from St. Paul to the 

western part of the State, James Hall: Trans. Am. Phil. Soc., vol.xm, new series, 

pp. 329-340.

153 Report on the Geological Survey of the State of Iowa, containing Results of 

Examinations and Observations made within the years 1866, 1867, 1868, and 1869, 

Charles A. White. Des Moines, 1870, pp. 391.

IBS pir8t Annual Report Geological and Natural History Survey of Minnesota, N. 

H. Winchell, pp. 129.

IB4 The Geology of the Minnesota Valley, N. H. Winchell. Second Report on the 

Geol. and Nat. Hist. Survey of Minn., pp. 127-212.
206 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

165 Ueber die Krystallinischen Gesteine von Minnesota in Nord-Amerika, A. Strong 

and J. H. Kloos. Leonhard's Jahrbuch, 1877, pp. 31,113, 225. Translated by N. H. 

Winchell in llth Ann. Rept. Geol. and Nat. Hist. Survey of Minn., pp. 30-85.

166 Sixth Ann. Rept. Geol. and Nat. Hist. Survey of Minn. for 1877, N. H. Winchell, 

pp. 226.

187 Sketch of the Work of the Season of 1878, N. H. Winchell. Seventh Ann. Rept. 

Geol. and Nat. Hist. Survey of Minn. for 1878, pp. 9-25.

168 The Cupriferous Series at Duluth, N. H. Winchell. Eighth Ann. Rept. Geol. 

and Nat. Hist. Survey of Mitm. for 1879, pp. 22-26.

169 Preliminary Report on the Geology of Central and Western Minnesota, Warren 

Upham. Ibid., pp. 70-125.

'6° Report of Prof. C. W. Hall. Ibid., pp. 126-138.

lei Preliminary List of Rocks, N. H. Winchell. Ninth Ann. Rept. Geol. and Nat. 

Hist. Survey of Minn. for 1880, pp. 10-114.

162 The Cupriferous Series in Minnesota, N. H. Winchell. Proc. Am. Assoc. Adv. 

Sci., 29th Meeting, pp. 422-425. See also, Ninth. Ann. Rept. Geol. and Nat. Hist. Survey of Minn. for 1880, pp, 385-387.

les Preliminary List of Rocks, N. H. Winchell. Tenth Ann. Rept. Geol. and Nat. 

Hist. Survey of Minnesota for 1881, pp. 9-122.

184 Notes on Rock-outcrops in Central Minnesota, Warren Upham. Eleventh Ann. 

Rept. Geol. and Nat. Hist. Survey of Minn. for 1882, pp. 86-136.

IDS The Iron Region of Northern Minnesota, Albert H. Chester. Ibid., pp. 154-167.

168 Note on the Age of the Rocks of the Mesabi and Vermilion Iron District, N. H. 

Winchell. Ibid., 168-170. See also Proc. Am. Assoc. Adv. Sci. 1884, 33rd Meeting, pp. 

363-379.

167 The Geology of Minnesota, N. H. Winchell and Warren Upham. Vols. I and n of 

the Final Report, pp. 697, 695.

168 Notes of a trip across the Mesabi Range to Vermilion Lake, N. H. Winchell. 

13th Ann. Rept. Geol. and Nat. Hist. Survey of Minn. for 1884, pp. 20-24. The Crystalline Rocks of Minnesota, N. H. Winchell. Ibid., pp. 36-38.

169 Fossils from the Red Quartzite at Pipestone, N. H. Winchell. Ibid., pp. 65-72. 

170 Notes on the Geology of Minnehaha County, Dakota, Warren Upham. Ibid., pp. 

88-97.

171 The Crystalline Rocks of the Northwest, N. H. Winchell. Ibid., pp. 124-140.

172 Report of Geological Observations made in Northeastern Minnesota during the 

Season of 1886, Alexander Winchell. 15th Ann. Rept. Geol. and Nat. Hist. Survey of 

Minn.-for 1886, pp. 5-207.

m Geological Report of N. H. Winchell. Ibid., pp. 209-399, with a map.

17< Report of N. H. Winchell. 16th Ann. Rept. Geol. and Nat. Hist. Survey of Minnesota for 1887, pp. 13-129.

175 Report of Alexander Winchell. Ibid., pp. 133-391. See also The Unconformities 

of the Animikie in Minnesota. Am. Geol., vol. I, pp. 14-24; Two Systems Confounded 

in the Huronian. Ibid., vol. in, pp. 212-214, 339-340. Systematic Results of a Fit-Id 

Study of the Archean Rocks of the Northwest. Proc. Am. Assoc. Adv. Sci., 37th 

Meeting, p. 205; The Geological Position of the Ogishki Conglomerate. Ibid., 1889, 

38th Meeting, pp. 234-235.

178 Report of H. V. Winchell. Sixteenth Ann. Rept. Geol. and Nat. Hist. Survey 

of Minn. for 1887, pp. 395-462, with map.

i" A Great Primordial Quartzite, N. H. Winchell. Am. Geol., vol. I, pp. 173-178. 

See, also, Seventeenth Ann. Rept. Geol. and Nat. Hist. Survey of.Minn. for 1888, pp. 

25-56.

178 Report of N. H. Winchell. Seventeenth Ann. Rept. Geol. and Nat. Hist. Survey 

of Minn. for 1888, pp. 5-74; see also The Animikie Black Slates and Quartzites, and 

the Ogishki Conglomerate of Minnesota, the equivalent of the "Original Huronian." 

Am. Geol., vol. i, pp. 11-14; Methods of Stratigraphy in Studying the Huronian. 

Ibid., vol. iv, pp. 342-357.
VAN HIHB.]" LAKE SUPERIOR REGION. 207

170 Report of Field Observations made during the season of 1888 iu the Iron Regions 

of Minnesota, H. V. Winchell. Seventeenth Ann. Rept. Geol. and Nat. Hist. Survey 

Of Minn. for 1888, pp. 77-145; see also The Diabasic Schists Containing the Jaspilyte 

Beds of Northeastern Minnesota. Am. Geol., vol. in, pp. 18-22.

180 Report of Geological Observations made in Northeastern Minnesota during the 

summer of 1888, Uly S. Grant. Seventeenth Ann. Rept. Geol. and Nat. Hist. Survey 

of Minn. for 1888, pp. 149-215.

181 Conglomerates Enclosed in Gneissic Terraues, Alexander Winchell. Am. Geol., 

vol. in, pp. 153-165, 256-262.

182 Some Thoughts on Eruptive Rocks with Special Reference to those of Minnesota, 

N. H. Winchell. Proc. Am. Assoc. Adv. Sci., 1888, 37th Meeting, pp. 212-221.

183 The Stilhvater, Minn., Deep Well, A. D. Meads. Am. Geol., vol. in, p. 342.

184 On a Possible Chemical Origin of the Iron Ores of the Keewatin in Minnesota, 

N. H. and H. V. Winchell. Ibid., vol. iv, pp. 291-300, 382-386. Also Proc. Am. 

Assoc. Adv. Sci., 1890, 38th Meeting, pp. 235-242.

185 Some Results of Archean Studies, Alexander Winchell. Bull. Geol. Soc. of 

America, vol. I, pp. 357-394.

186 The Tacouic Iron Ores of Minnesota and of Western New England, N. H. and 

H. V. Winchell. Am. Geol., vol. vi, pp. 263-274.

187 Record of Field Observations in 1888 and 1889, N. H. Winchell. 18th Ann. Rept. 

Geol. and Nat. Hist. Survey of Minn. for 1889, pp. 7-47.

188 The Iron Ores of Minnesota, N. H. and H. V. Wiuchell. Bull. No. 6. Geol. and 

Nat. Hist. Survey of Minn., pp. 430; with a geological map.

189 Geological Aee of the Saganaga Syenite, Horace V. Winchell. Am. Jour. Sci., 

3d ser., vol. XLI, 1891, pp. 386-390.

19(1 Sketch of the Geology of Northeastern Dakota, with a notice of a short visit to 

the celebrated Pipestone Quarry, F. V. Hayden. Am. Jour. Sci., 2d series, vol. XLIII, 

pp. 15-22.

191 The Copper-Bearing Rocks of Lake Superior, R. D. Irving. U. S. Geol. Survey 

Monograph v, pp. 464,15 1., 29 pi. and maps. See also the Copper-Bearing Rocks of 

Lake Superior, R. D. Irving. Third Ann. Rept. U. S. Geol. Survey 1881-'82, pp. 

89-188; 15 pi. and maps. The Copper-Bearing Rocks of Lake Superior, R. D. Irving. Science, vol. i, pp. 140, 359 and 422. The Copper-Bearing Rocks of the Lake 

Superior Region. Am. Jour. Sci., 3d ser., vol. xxvm, p. 462, vol. xxix, pp. 67-68, 

258-259, 339-340.

192 The Copper-Bearing series of Lake Superior, T. C. Chamberliu. Science, vol. 

I, pp. 453-455.

193 On Secondary Enlargements of Mineral Fragments in Certain Rocks, R. D. Irviiig and C. R. Van Hise. Bull. U. S. Geol. Survey, No,8, 56 pp., 6 pi.

194 Observations on the Junction between the Eastern Sandstone and the Keweenaw 

Series on Keweenaw Point, Lake Superior, R. D. Irving and T. C. Chaniberlin 

Bull. U. S. Geol. Survey, No. 23, 124 pp., 17 pi.

195 Divisibility of the Archaean in the Northwest, R. D. Irving. Am. Jour. Sci., 3d 

series, 1885, vol. xxix, pp. 237-249.

i% Preliminary Paper on an Investigation of the Archaean Formations of the Northwestern States, R. D. Irving. Fifth Ann. Rept. U. S. Geol. Survey, 1883-'84, pp. 

175-242, 10 pis.

197 Origin of the Ferruginous Schists and Iron Ores of the Lake Superior Region. 

R. D. Irving. Am. Jour. Sci., 3d ser., vol. xxxn, pp. 255-272.

198 Report of a Trip on the Upper Mississippi and to Vermilion Lake, Bailey Willis. 

10th Census Report, vol. xv, pp. 457-467.

199 Is there a Huronian Group? R. D. Irving. Am. Jour. Sci., 3d ser., vol. xxxiv, 

1887, pp. 204-216, 249-263, 365-374.

*°°On the Classification of the Early Cambrian and Pre-Cambriau Formations, R. 

D. Irving. Seventh Ann. Rept. U. S. Geol. Survey, 1885-'86, pp. 365-454, with 22 pis. 

and maps.
208 . PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

201 The. Iron Ores of the Penokee-Gogebic Series of Michigan and Wisconsin, C. R. 

Van Hise. Am. Jour. Sci., 3d ser., vol. xxxvn, pp. 32-48, with plate.

202 The Distribution of the Granites of the Northwestern States, and their general 

lithologic characters, C. W. Hall. Proc. Am. Assoc. Adv. Sci., 37th Meeting, 1889, p. 

189.

203 The Greenstone Schist Areas of the Menominee and Marquette Regions of Michigan, George Huntington Williams. Bull. U. S. Geol. Survey No. 62, pp. 31-238, with 

16 pis. and maps. See also, Some examples of Dynamic Metamorphism of the Ancient 

Eruptive Rocks on the South Shore of Lake Superior. Proc. Am. Assoc. Adv. Sci., 

36th Meeting, pp. 225-226.

204 Explanatory and Historical Note, R. D. Irving. Bull. U. S. Geol. Survey, No. 

62, pp. 1-30.

205 The Penokee Iron-Bearing Series of Michigan and Wisconsin, R. D. Irving and 

C. R. Van Hise. U. S. Geol. Survey, Monograph xix, pp. , with pis. and maps. 

See also Tenth Ann. Rept. U. S. Geol. Survey, 1888-'89, 341-507, with 23 pis. and 

maps.

206 An attempt to Harmonize some Apparently Conflicting Views of Lake Superior 

Stratigraphy, C. R. Van Hise. Am. Jour. Sci., 3d ser., vol. XLI, 1891, pp. 117-137.

207 Notes on the Petrography and Geology of the Akeley Lake Region, in northeastern Minnesota, W. S. Bayley. 19th Ann. Rept. Geol. and Nat. Hist. Survey of 

Minn. for the year 1890, pp. 193-210.

' ""' Based on unpublished field notes made by W. N. Merriam in the summers of 1888 

and 1889.

209 Based on unpublished field notes made by C. R. Van Hise in the summer of 1890.

2111 Based on unpublished field notes made by Profs. Raphael Pumpelly and C. R, 

Van Hise in the summers of 1891 and 1892.
OHAPTEE III.

THE GREAT NORTHERN AREA.

SECTION I. THE REGION ABOUT HUDSON BAT.

LITERATURE.

BELL, 1 in 1877, reports on explorations between James bay and lakes 

Superior and Huron. The rocks are described as Huronian on the 

course followed until the north side of Shatagami.lake is reached, with 

the reservation that the gneiss just below Paul's lake may be Laurentian. In this distance the rocks are limestones, quartzite, diorite, chertslate-conglomerate, hornblende-schist, pegmatite, syenite, clay-slates, 

and, at Paul's lake, gneiss. The diorites have a widespread occurrence, 

and an area of massive syenite continues for several miles in one local, 

ity. It is often mixed with crystalline diorite. Beyond Shatagaini 

lake are several alternations of rocks which are referred to the Huronian and Laurentian before the fossiliferous series is reached. The conspicuous feature of the last Laurentian belts are large diorite dikes. 

The junction of the Laurentian and Huronian occurs at Davis's rapid, 

51 miles north of the outlet of lake Kenohamissee.

On the return trip the course followed is by the west branch of 

Moose river, along toward its headwaters, thence to Michipicoten and 

lake Superior. The rocks are chiefly granite and syenite, gneiss, hornblende-schists and mica-schists and greenish schists. These are in part 

referred to the Huroniau and in part to the Laurentian, several belts 

of the Huronian being found. At one place the Huronian is spoken of 

as passing into the Laurentian. As a result of othe work it is shown 

that an immense area of Huronian rocks runs northward from lake 

Huron through the greater part of the distance lying between it and 

the area of unaltered rocks of the southwest side of James bay.

BELL,Z in 1879, reports on explorations of the east coast of Hudson 

bay. In this region are large areas of gneisses which are referred to 

the Laurentian, and belts of schists referred to the Huronian. With 

the Hurojiian are schist-conglomerates and quartzites. At the contact 

of the Laurentian and Huronian, the former consists of a coarse quartz 

and mica rock, while the first rock which is considered Huronian is a 

dark green, highly crystalliae hornblende-schist. The two formations 

appear as usual to be conformable. Along Manitounuck sound is an 

unaltered stratified series in which no fossils were found and which 

resemble the Nipigon rocks, These are called the Mauitounuck group,

209 

Bull. 86 14
210 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

They consist mostly of siliceous and argillaceous limestones, sandstones, 

quartzites, shales, ironstones, amygdaloids, and basalts. At Little 

Whale river is a quartz-conglomerate of great thickness below these 

rocks. The limestones are found at many localities at the base of the 

series. They have a cherty concretionary and concentric structure. 

The quartzites and sandstones come in ascending order. Associated 

with the quartzites, and overlying them, is a series of cherts and shales. 

These are surmounted by a great thickness of amygdaloids of various 

kinds and of diorites of a basaltic character. At Richmond gulf the 

base of the section consists of sandstone and conglomerate, above which 

is limestone in a slightly uncoiiformable position and all is capped by 

trap. In one place the trap rests with a slight unconformity upon ferruginous beds. Spathic iron ore, sometimes of considerable thickness, 

is sometimes interstratified with the sandstone.

BELL,3 in 1879, reports on the country between lake Winnipeg and 

Hudson bay. The rocks along the route, with the exception of one Huronian trough, are described as Laurentiau gneiss. The Huronian rocks 

belong in one basin or trough, conforming with the general trend of 

the Laurentian gneiss and mica-schist. Its breadth is about 14 miles 

and its length 143 miles, giving an area of about 2,000 square miles. A 

mica-schist at Pipestone lake contains different kinds of pebbles. At 

Seven-mile point the rock is a micaceous slate-conglomerate, the pebbles 

of which are chiefly of gray syenite. At the junction of the Laurentian 

and Huronian the two formations appear as usual to be conformable 

with each other. The last of the Laurentian series consists of gray 

coarse, rough-surfaced quartz and mica rock. The first rock on what is 

considered to be the Huronian side of the boundary consists of highly 

crystalline dark green hornblende-schist, ribboned with fine lines of 

white quartz grains. This schist is interstratined with bands of finely 

ribboned, slightly calcareous gray gneiss.

BELL,4 in 1880, reports on explorations of the Churchill and Nelson 

river and around God's and Island lakes. The Laurentian gneiss is the 

prevailing rock throughout the whole district between Knee and Island 

lakes. The stratification, while moderately distinct, is often banded and 

contorted. Its average texture is of a medium variety, or rather tending 

to fine grain, but coarse forms are occasionally seen. There is no prevailing or general direction in the strike of the gneiss. The Huronian 

rocks occupy a series of troughs in several localities. The rocks are 

schist-conglomerate, sometimes garnetiferous, steatite-schists, green 

schists and felsite schists, most of them being more or less calcareous. 

The Laurentian gneiss occupies the area between the Huronian troughs. 

The strike of the Laurentian gneiss in the neighborhood of the Huronian rocks appears in most cases to correspond with that of the latter.

BELL,* in 1881, reports on Hudson bay and some of the lakes and 

rivers lying to the west of it. Various gneisses and schists are found 

at different points which are referred respectively to tlie Laurentian and
U.S. GEOLOGICAL SURVEY. 

GEOLOGICAL MAP OF ORTHERN CANADA

SHOWING PRE-CAMBRIANiND CRYSTALLINE ROCKS

Complied from Official Maps j the Canadian Geol. Survey Scale. 2J.9000.
VANHISB.] THE GREAT NORTHERN AREA. 211

Huronian. Hudson bay as a whole lies in the great Laurentian area 

of the Dominion. The long chain of islands which fringe the east coast 

are composed of bedded volcanic and.almost unaltered sedimentary 

rocks, resembling the Nipigon series of lake Superior, which may be of 

Lower Cambrian age. On the western side of the bay, from the Churchill 

river northward, quartzites and other rocks are found which may also 

belong to the Cambrian system. Cambro-Silurian rocks rest almost 

horizontally upon the Laurentian along the southwestern side of the bay.

BELL,6 in 1883, reports upon the geology of the basin of Moose river 

and adjacent country. The boundaries of the Laurentian and Huronian formations appear to be conformable to each other. Massive 

granites occur abundantly with the Laurentian gneisses and Huronian 

schists. The granites generally lie close to the junction of the Hurouian and Laurentian, this being the usual position of these granite 

areas in the great region northward of lakes Huron and Superior.

BELL,7 in 1885, describes granite and gneiss at North head, Button 

islands, Ungava bay, Nunaungok, Ashe's inlet, Nottingham and Digges 

islands, Stuparts bay, Eskimo inlet, port DeBoucherville, and port 

Laperriere. A portion of the west coast of Hudson bay is occupied 

with diorites, hornblende-schists and mica-schists, which may be referred to the Huronian series. Deadman's island consists of white 

and light-gray quartzites, and glossy mica-schists, striking north 75° 

west. The whole of the western part of Marble island consists of white 

and light colored quartzite bearing a strong resemblance to Avhite and 

vein marble. The beds of quartzite are very massive, although their 

surfaces are often ripple-marked, being sometimes as fine and regular 

as the fluting on a washboard.

B ELL,8 in 1885, gives a general characterization of the geology of 

Hndson bay. The distribution of the Huronian series is intimately connected with that of the Laurentian, being found mostly within the 

limits of the latter. The rocks of the Huronian system appear to rest 

conformably upon the Laurentian in all cases observed. About the 

mouth of Churchill river, on the west side of the bay, and for some 

miles along the coast, are found massive and thinly bedded quartzites 

with conglomerate beds, the pebbles being mostly of white quartz, interstratified with occasional thin shaly. layers. These strata may form 

a part of the Huronian series, but they also resemble the gold-bearing 

rocks of Nova Scotia. On the Little Whale river and in Richmond 

gulf on the east side of the bay another set of rocks is found following 

the Huronian and underlying unconformably the Mpigon series. This 

intermediate formation consists of beds of hard red siliceous conglomerate and red and gray sandstones, with some red shales, and appears 

to have a considerable volume. The Nipigon formation is largely developed along the east main coast of Hudson bay, between cape Jones 

and cape Dufferin, and consists of compact, nonfossiliferous, bluish 

gray limestones, coarse cherty limestone breccias, quartzites, shales,
212 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BOLL. 86.

diorites, amygdaloids, and manganiferous clay ironstones. The limestones of lake Misstassini, in the interior of the Labrador peninsula, 

bear a strong resemblance to those of the east main coast.

BELL, 9 in 1886, gives additional observations on the geology of Hudson bay. From Eskimo point to the entrance of Chesterfield inlet, a 

distance of 180 miles, the rock specimens embrace hornblende-schists, 

greenstones, sandstone altered to quartzite and holding fragments of 

indurated shale, white quartz rock, quartzite like that of Marble island 

felsite, crystalline hornblende rock, diorite, chert, mica-schist, porphyry, 

granulite, red jasper, chloritic schists, etc. The majority of the lithological specimens correspond with the rocks of the Huronian series, 

Laurentian types are absent, and the probabilities are that Huronian 

rocks prevail all along the northwest coast of Hudson bay, from Eskimo 

point to Chesterfield inlet, and again at Eepulse bay. The widely extended areas of massive granitoid character about Hudson bay are 

regarded as primitive gneiss, and there is little doubt are more ancient 

than the regularly stratified gneisses which prevail on the Ottawa valley. The Huronian rocks of the region are unlike those on the north 

shore of lake Huron, consisting of massive diorites, argillaceous and 

dioritic slate conglomerates, granite-syenites, schistose and jaspery 

iron ores, limestones, dolomites, and imperfect gneisses^ with a great 

variety of schists. The Manitounuck series is largely made up of rocks 

of volcanic origin.

BELL,10 in 1887, reports on explorations of portions of the Attawapishkat and Albany rivers. Various granites, gneisses, and schists 

are found upon Pelican lake, lake St. Joseph, and the upper sections 

of Albany and Boulder rivers, and lake Lansdowne. "Upon lake St. 

Joseph a conglomerate is found. The granites and gneisses are placed 

with the Laurentian and the schists and conglomerates with the Huronian.

SUMMARY OF RESULTS.

In all of the above works by Bell the rocks are classified as Laurentian or Huronian almost wholly upon lithological grounds, the coarse 

granites and granitoid gneisses being regarded as Laurentian and 

the clearly sedimentaiy rocks and fine grained calcareous gneisses 

and various green schists with associated rocks being placed as Huronian. Whenever the relations of the two series are spoken of they 

are said to be in conformity. The Huronian is, however, frequently 

spoken of as occurring in troughs, which probably implies that this 

series is taken to be the newer of the two; but in general this is an 

inference from its lithological character rather than a determination 

from an ascending succession. The dips are usually high and no 

structure is worked out, so that from the facts given it would be impossible to determine which is higher and which lower, except by the 

implication Jn tfc© words Huronian and Laurentian. While certain of
VANHISE.] THE GREAT NORTHERN AREA. 213

tlie rocks placed with the Hurouian are lithologically like those of the 

Original Hurouian, Bell distinctly states that in the main they are quite 

different. The likeness apparently goes no further than the fact that 

occasionally there are found unmistakable clastic rocks, and some of 

these elastics resemble more closely the fragmentals of the Ottawa 

series than they do those of the Original Huronian.

The Manitounuck group on Hudson bay, which is described as resembling very closely the Mpigon series, is, from the illustrations, a 

comparatively flat-lying one and is probably newer than either of the 

series referred to the Laurentian or Huronian. At least two unconformities are mentioned in it, one between two sedimentary rocks and 

another between a sedimentary rock and a trap. These unconformities 

are spoken of as slight, but the cuts illustrative of them represent the 

first of these unconformities as very considerable.

SECTION II. NORTHERN CANADA.*"

LITERATURE.

STEINHAUER," in 1814, gives localities for la,bradorite on the coast of 

Labrador.

McOuLLOCH, 12 in 1819, describes as coming from Baffin bay, 70° 37', 

granite, gneiss, and graywacke-schist.

BiCHARDSON, 13 in 1823, describes clay-slate as occurring in the northern arm of Great Slave lake. North of Great Slave lake the granite 

formation continues for a considerable distance toward Fort Enterprise, 

but contains more foreign beds in advancing to the north ward. In this 

region in places mica-slate prevails and in other places the granite contains beds of mica-slate. Gneiss appears to exist throughout the great 

district to the eastward of Coppermine river. About Fort Enterprise 

are numerous hills capped by red granite, around which, on the acclivities, gneiss is wrapped in a mantle form. The rocks of this district include granite, micaceous and hornblendic gneiss, greenstone, mica-slate, 

and clay-slate. At Point lake are found graywacke-slate, clay-slate, 

and transition greenstone slate, as well as transition conglomerate, the 

fragments of which appear to consist of the same material with the 

bases. In the first part of the region of Coppermine river, between 

Point lake and the sea, are found granite, syenite, gneiss, clay-slates, 

and hills of trap. North of latitude 66° 45' 11" are found red and gray 

sandstones, compact feldspar rock, granular foliated limestone, trap 

rock, and greenstone which constitutes the Copper mountains. In 

these mountains are amygdaloids which contain amygdules of pistacite 

and calc-spar, scales of copper being generally disseminated through the

*This section is largely compiled from Geo. M. Dawson's account of this region accompanying his 

geological map of it. With a number of exceptions the original reports have not been seen. This 

unusual plan is bere adopted because Dawson's summary of the geological material, widely scattered 

through the many volumes of Arctic travel, is so complete as to render unnecessary the labor of 

going through them a second time.
214 PRE-CAMBRIAN ROCKS OF KORTH AMERICA. [BULL. 86.

rock. In. this region were also found masses of native copper and prehnite. The shores of Bathurst inlet are partly of granite and gneiss and 

partly of later rocks. On the road from Bathurst inlet to Point lake 

and Fort Enterprise, beyond Hood's river, the rocks are entirely gneissic 

or granitic.

PARRY,14 in 1824, found granitic and gneissic rocks to occupy the 

whole southern part of the east shore of Melville peninsula and to 

continue northward behind a tract of limestone country, forming a 

range of mountains in the center of the peninsula to Hecla-and-Fury 

strait. They also form the south shore of this strait, most of the islands 

adjacent to it, and apparently the whole eastern shore of the adjacent 

south part of Cockburn "island."

KoNiNGr, 15 in 1824, describes the most characteristic rock collected by 

Capt. Parry on the west coast of Baffin bay as gneiss and micaceous 

quartz rock, with some ambiguous granitic compound in which hornblende seems to enter as a subordinate ingredient.

LYON,IG in 1825, describes cape Fullerton on the main shore west of 

Southampton island to be composed of rugged red and gray granitic 

rocks with the strata running in a northwest direction.

JAMESON,17 in 1826, states that the material collected by Capt. Parry 

shows that the west coast of Davis strait and Baffin bay, south of 

Lancaster sound, consists of primitive rocks, among which are gneiss, 

mica-slate, hornblende-slate, granite limestone, hornblende-rock, and 

greenstone. All these rocks are more or less distinctly stratified and 

numberless transitions from one into the other were observed.

RICHARDSON, in 1828, describes the rocks of the Coppermine river 

series as extending westward to the Height of Land' and consisting 

chiefly of sandstone and conglomerates with granite and porphyry. 

The southeast extremity of McTavish bay consists of red granites and 

gneisses. At the mouth of Dease river and the northeast extremity of 

the lake the prevailing formation is granitic and gneissic. On mount 

Fitton, along the Arctic coast west of the Mackenzie river, the mountain range consists of gray wacke slates which are considered transition 

rocks.

LESLIE, JAMESON, and MURRAY (Huan),19 in 1830, mention in the 

region of Southampton island, Melville peninsula, and Hecla-and-Fury 

strait, as prominent varieties of rock, granite, gneiss, mica-slate, clayslate, chlorite-slate, primitive trap, serpentine, limestone, and porphyry. 

The Primitive range bordering the east coast of Baffin land is a continuation of the Labrador coast; and on the west coast of Davis strait and 

Baffin bay, south of Lancaster strait, primitive rocks preponderate, 

including gneiss, mica-slate, and granite.

Boss,20 in 1835, finds granitoid and gneissic rocks to occupy exclusively the coast line and adjacent islands of the Boothian and M'elville 

peninsula south of 70° 35'.

FiTTON,21 in 1836, describes the north side of Great Slave lake from
VANHIBE.] THE GREAT NORTHERN AREA. 215

the entrance of the north arm westward as consisting mainly of gneiss, 

porphyry, and granite. The large islands and promontory of the eastern part of the lake are of the trap formation. These are compared to 

the Coppermine series. Pebbles of jasper conglomerate were collected 

near the west end of the lake, but the rock was not seen in place. The 

rocks on the route from Great Slave lake northeastward by ClintonGolden and Aylmer lakes and the Great Fish river to the Arctic coasts 

are different varieties of granite and gneiss.

BACK,22 in 1838, describes granite as occurring in two places along 

the southeastern coast of Southampton island.

SiMPSON,23 in 1843, applies the name Trap Point to the Kent peninsula. After an interval of low ground to the eastward granite forms 

the coast line.

EAE,24 in 1850, finds north of latitude 61° on the west coast of Hudson bay, beyond Nevill's bay, the shore steep and rugged, being 

lined with bare primitive rocks. On the southern shores of the gulf of 

Boothia granite occurs in several places, and among the specimens 

found are gneiss, mica-slate, quartz-rock, hornblende-slate. Precipitous 

cliffs of trap were found on Simpson bay, in latitude 08° 27'.

RICHARDSON,25 in 1851, states that the eastern side of the north arm 

of Great Slave lake is occupied by primitive rocks, which run across 

the outlet of Athabasca lake to the deep, northern arm of Great Slave 

lake, and onward by Marten lake, across the two eastern arms of 

Great Bear lake,' to the Copper mountains. On Eae river, which flows 

into Coronation gulf near the mouth of the Coppermine, are limestone, 

quartz-rock, and high cliffs of basalt. From the similarity of the 

various rocks associated in this quarter to those occurring at Pigeon 

river and other parts of the north shore of lake Superior the author is 

inclined to consider that the two deposits belong to the same geological era, both being more ancient than the Silurian. At Eae river and 

Richardson river, to the northwest of the mouth of the Coppermine and 

on the west side of the Coppermine river, are series of basaltic cliffs.

SUTHERLAND,26 in 1853, describes the rocks at cape York and cape 

Atholl, latitude 76°, as consisting of sandstones, interstratified with 

volcanic material. On the east coast of Baffin land, from Lancaster 

sound to Cumberland sound, are crystalline rocks which occupy the 

whole coast southward to Cumberland strait.

MuRCHiSON,27 in 1857, states that cape Granite in the Arctic Archipelago is composed of quartz, feldspar, and chlorite, and is accompanied with gneiss of the same composition.

KANE,28 in 1857, states that the rocks of the coast between Rensselaer harbor and the great Humboldt glacier (in Peabody bay), are stratified limestones, sandstones, feldspathic and porphyritic granite passing into gneiss, and in some places trap.

HAUGHTON,29 in 1857, describes granitic rocks as composing a considerable part of Korth Greenland, on the north side of Baffin bay, and
216 PRE-CAMBRIAN EOCKS OF NORTH AMERICA. lBtnx.86.

constituting the rock of the country at the east side of the island of 

Forth Devon. Between capes Osborne and Warrender the rocks are 

graphic granite, which passes into a laminated gneiss, and with the 

gneiss are interstratified beds of garnetiferous mica-slate. The whole 

series is overlain by red sandstones of banded structure. The granitoid rocks are again found on the north side of the island of Forth Somerset, where they form the eastern boundary of Peel sound. Cape 

Granite is the northern boundary of the granite. On Peel sound and 

Prince of Wales island is a dark syenite composed of feldspar and 

hornblende. This rock is massive and eruptive at cape M'Clure, and 

occasionally gneissic. The Silurian of the Arctic archipelago rests 

everywhere directly on the granite, with a sandstone, passing into a 

coarse grit, at its base.

HATTCKHTON,29 in 1859, states that granitoid rocks everywhere underlie the Arctic archipelago. At Montreal island is a gneiss which exhibits the phenomena of foliation in a marked degree. At Beliefs straits, 

in latitude 72° north, are found gneissoid granite, graphic granite, and 

syenite. At Pond's bay, at the northern extremity of Baffin land, 

quartziferous mica-schist underlies the Silurian limestone and is interstratified with gneiss and garnetiferous quartz rock inclining 38° 

WSW. Cape York, on the Greenland coast, is composed of fine 

grained granite. At Wolstenholme sound the granitoid rocks are converted into mica-si ate and actinolite-slate, the two rocks passing into 

each other by almost insensible gradations. Carey's islands, west of 

Wolstenholme sound, are composed of a gneissose mica-schist, formed of 

successive layers of quartz granules, and layers of jet-black mica. The 

mica-schist passes into white gneiss. Yellow and white sandstones are 

also found in small quantity upon the islands, reposing upon the granitoid rocks.

LiEBER,30 in 1860, describes on the coast of Labrador, gneisses, granites, labradorites, etc., at various localities.

DERANGE and FiELDEN,31 in 1878, state that the Laurentian system 

is the fundamental one for the region visited by Sir George Fares. At 

cape Eawson is an important overlying series which occupies the 

coast of Grinnell land from Scoresby bay to cape Cresswell, in latitude 

82° 40' north. The rocks are in a series of sharp folds with a general 

west-southwest strike, the beds being often vertical and frequently 

cleaved. They consist of jet-black slates, of impure limestones, traversed by veins of quartz and cherts, and of a vast series of quartzites 

and grits. They are compared to the gold-bearing series of Fova Scotia 

and doubtfully referred to the Huronian system.

HiND,32 in 1878, describes at Mullens cove, in the Laurentian series 

of Labrador, a succession of interbedded gneisses, micaceous schists, 

crystalline limestones, and a bed of calcareous conglomerate. The 

thickest layer of white crystalline limestone is 35 feet.

EMERSON,33 in 1879, describes the rocks of Frobisher bay, collected
VANHISE.] THE GREAT NORTHERN AREA. 217

by 0. F. Hall, as consisting of granite, gneiss, magnetite-gneiss, hornblendic gneiss, mica-schist, etc.

BELL,U in 1885, describes on the Labrador coast gneiss and granite at Ford's harbor and Mission station, Nain, at Nachvak inlet, at 

Skynners cove, and other points. The granite sometimes becomes 

syenitic and the gneiss is sometimes well laminated.

BOAS,34 in 1885, describes the nucleus of Baffin land as everywhere 

of gneiss and granite.

GREELY,35 in 1886, finds toward the head of Chandler fiord high 

cliifs of schists and slate, and in Euggles river, at the outlet of lake 

Hazen, large slabs of slate.

PACKARD,36 in 1888, describes syenitic and gneissic rocks of the 

Laurentian formation at various points, among which are Sleupe harbor in Gore island near Shallop, the bay east of Ause-au-Loup, Caribou 

island, cape St. Francis, and Square island.

McCoNNELL,37 in 1890, mentions granite-gneisses east of the Eocky 

mountains at the rapids of Slave river and fort Eae. These evidently 

belong to the Laurentian or the oldest division of the Archean. West of 

the Eocky mountains, crystalline schists are largely developed along the 

valley of the Pelly-Yukon, occurring in numerous exposures from thje 

International boundary to fort Selkirk, and they continue up the Lewis 

about 30 miles. This belt of crystalline rocks has a width of somewhat 

over a hundred miles. The eastern edge of the area consists largely of 

quartzose schists, chlorite-schists, mjca-schists, diabases, and serpentines, which are occasionally interbedded with bands of slate, limestone, 

and are broken in many places by igneous intrusions. The green 

schists, in ascending the river, are underlain by foliated mica-gneisses, 

alternating with hornblende-gneisses, which are distinctly Archean in 

appearance and lithological character.

SUMMARY OF RESULTS FROM DAWSON.

DAWSON, 38 in 1887, as a result of an exhaustive review of the literature 

of northern Canada, states that Archean or Eozoic rocks are dominant 

in the northern part of the continent. They also form the greater part 

of Greenland, and doubtless underlie at no great depth the entire Arctic 

archipelago. While the information available is sufficient to indicate 

the existence of the different subdivisions of the Archean which are 

met with in the southern portion of Canada, including the lowest Laurentian or granitoid gneiss series, the Middle -Laurentian, possibly the 

peculiar rocks classed as the " Upper Laurentian " and certain of the 

more schistose and generally darker colored and more basic rocks classed 

as Huronian, it is far too imperfect to admit of the separation of these 

subdivisions on the map. It is evident that the Huronian is represented 

in parts of the west coast of Greenland, and it is probably also recognizable on the Labrador coast, and on the west coast of Hudson bay. 

The occurrence of well stratified gneisses with mica-schists and crystal-
218 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. . [BULL. 86.

line limestones, with associated graphite and magnetite, appears to indicate the presence of Middle Lanrentian. These rocks occur on the 

southern part of Baffin land, Frobisher bay, Cumberland sound, and 

Melville peninsula. The term Cambrian is made to include all rocks 

above the Huronian to the base of the Cambro-Silurian. Extensive 

areas placed in the Cambrian on the Arctic coast and in the vicinity of 

Coppermine river are analogous in character to those of the Keweenaw 

or Animikie of the lake Superior region, and probably represent both 

groups of that great copper-bearing series. Throughout the northern 

part of the continent the characteristic Cambrian formation, composed 

largely of volcanic rocks, apparently occupies an unconformable position 

with regard to the underlying Laurentian and Huronian systems. The 

present remnants show that these rocks have undergone comparatively 

little subsequent disturbance. The cape Rawson beds of Grinnell land 

are provisionally referred to the Cambrian, on account of their lithological resemblance to the rocks of the Animikie, and also on account of 

their similarity to the Nova Scotia gold-bearing series.

In the above summary, as the terms are used in this volume, the Middle Laurentian, much of the Huronian, and the Coppermine and equivalent series, which are placed in the Cambrian, are to be included in the 

Algonkian; while the Lower Laurentian is largely or wholly Archean.

SECTION III. THE LOWER ST. LAWRENCE RIVER AND WESTWARD TO 

LAKES ST. JOHN AND MISSTASSINI.

LITERATURE.

BAYFIELD,39 in 1840, describes granite rocks as occupying the following districts: Along the St. Lawrence from the Saguenay to pointe de 

Mcnts, a distance of 130 miles; from pointe de Monts to the Seven 

islands, a distance of 60 miles; the main] and to the eastward of Mingan 

islands and opposite Ste. Genevieve island, where the country for many 

miles inland is composed of low granite mounds; the coast from Ste. 

Genevieve east to cape Whittle, longitude 60° W., latitude 50° 10' H". 

The granites are in part hornblendic and in part nonhornblendic. At 

Ste. Genevieve was observed hypersthene and Labrador feldspar. The 

granitic rocks are regarded as unstratifiecl. They are traversed by 

trap veins, insignificant in size as compared with the immense size of 

the lake Superior granite masses. Eeposing horizontally on the granites 

on the east side of Pillage bay and mount Ste. Genevieve are limestones. 

The islands of the south shore of the St. Lawrence and the south coast 

from Saguenay to cape Eozier are composed of alternating strata of 

graywacke and slate dipping to the southward at angles varying from 

30o to 90°.

Loo-AN,40 in 1850, describes a metamorphic group of rocks in the 

vicinity of bay St. Paul, Murray bay, and "White cape on the St. Lawrence river. The predominant rocks are mica-gneisses and hornblendegneisses. No crystalline limestones were noted.
VANHISE.] THE GREAT NORTHERN AREA. 219

LoGAN,41 in 1854, describes the district north of the St. Lawrence 

river, between Montreal and cape Tonrment, below Quebec. To the 

metainorphic sediments the word Laurentian is applied. It is used to 

cover all of the prefossiliferous rocks. The name is founded on that 

given by Mr. Garneau to the chain of hills which the Laurentiau 

series compose. At St. Maurice the Potsdam sandstone rests upon the 

gneiss.

DAWSON,42 in 1861, describes the Lanientian rocks exposed on the 

coast cliffs of Murray bay. At oue place the succession includes 

gneiss, white quartz rock, impure limestone, and hornblende slate, but 

the beds are so inverted that little reliance can be placed on apparent 

superposition. The crystalline limestone, dolomite, and serpentine are 

together 14 feet thick. The Silurian rocks rest unconformably upon 

the Laurentian beds.

EiCHARDSON,43 in 1870, describes the Laurentian and Labradorite 

rocks on the north shore of the lower St. Lawrence. The Laurentian 

gneiss has sometimes little appearance of stratification. The dips are 

high, approaching the vertical. The Labradorite, with moderate dips, 

rests unconformably upon the Laurentian. At one place there occurs 

in the gneiss a bed 12 feet thick of coarsely crystalline limestone. The 

Labradorite rocks have a wide extent. Both the Laurentian gneiss and 

labradorites are cut by granitic veins.

EiCHARDSON,44 in 1872, reports on the prefossiliferous rocks in the 

country north of lake St. John. They are classified under two heads: 

First, Laurentian gneiss, including a little crystalline limestone; second, crystalline schists, consisting of chloritic and epidotic rocks, with 

dolomites, serpentines, and conglomerates. The Laurentian occupies 

much the largest area of country and includes gneissic rocks cut by 

granite veins, limestones, quartzites, and hornblende rocks. The limestones and quartzites are comparatively unimportant, but the former is 

said to be in thickness not less than 500 or 600 feet. The rocks of the 

second class immediately succeed the Laurentian near the north end of 

lake Abatagomaw. Large expanses of the conglomerate of this series 

are composed entirely of rounded fragments of Laurentian gneiss of 

gray and red colors. In some places, without close examination, the 

conglomerate might be mistaken for the Laurentian gneiss. Sandstones 

and shales are met with which show lines of deposition. It is remarked 

that whatever the geological horizon of this series of rocks, it will be 

prudent for the present to withhold an opinion until further investigations are made. The only indication as to the geological age of this 

series is given by an obscure fossil occurring in a limestone which 

Billings thinks is a coral.

LAFLAMME,45 in 1885, gives geological observations on the Sagueuay 

region. The pre-Cambrian rocks are divided into two series, a gneissic 

and alabradorite series, which are together included in the Laurentian, 

although nothing is said as to their structural relations.
220 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL.86.

Low,46 in 1886, reports on the Mistassini expedition. The Laurentian 

gneisses and associated rocks occupy the whole country from the gulf 

of St. Lawrence to James bay, along the route traversed, with the exception of some areas of Huronian and Cambrian in the vicinity of lake 

Mistassini. The Laurentian rocks include gneiss, hornblende-schists, 

mica-schists, crystalline limestones, and areas of triclinic feldspar rocks. 

The rocks described by Eichardson, north of lake Abatagomaw, are similar to the epidotic and chloritic slates of the Shickshock mountains and 

the eastern townships and are referred to the Hurouian.

SUMMARY OF RESULTS.

In the very brief and general studies of the area north of the lower 

St. Lawrence no attempt is made to map the region in detail nor to 

work out the structure of the rocks. The Labradorite rocks are separated by Eichardson from the gneissoid rocks, to which he applies the 

term Laurentian. The reason for doing this is not given, so that we 

have no indication as to whether this is an eruptive or a sedimentary 

series, and if sedimentary, whether it underlies or overlies the gneisses. 

As JD the Ottawa region, the great mass of gneiss is free from limestones. The limestones are local and are associated with other rocks 

which are presumably of clastic origin, such as quartzites.

The remarks which are made with reference to two series in the 

Ottawa area would apply equally well to this region. We have no indication as to the relations of the clastic series, described by Eichardson, to the Laurentian gneiss which is referred by Low to the Huronian. 

Eichardson, who did the work upon this series, was not able to give an 

opinion as to its position, and its reference to the Huronian by Low is 

made wholly upon lithological grounds. It is, however, probable that 

the great conglomerates in the neighborhood of Lake Abatagomaw, composed almost entirely of rounded fragments of Laurentian gneiss and 

which in some places closely resemble the gneiss, mark the structural 

boundary between the two series of rocks. The description of this conglomerate is that of a recomposed rock, the material being derived from 

the immediately underlying formation.

NOTES.

1 Report on an Exploration in 1875 between James bay and lakes Superior and 

Huron, Robert Bell. Rept. of Prog. Geol. Survey of Canada for 1875-'76, pp. 294-342.

2 Report on an Exploration of the East Coast of Hudson Bay, Robert Bell. Rept. 

of Prog, of Geol. Survey of Canada for 1877-;78, pp. 1-37 C. With a map.

3 Report on the country between Lake Winnipeg and Hudson's Bay, Robert Bell. 

Ibid., pp. 1-31 CC. With 5 plates and 2 maps.

4 Report on Explorations of the Churchill and Nelson Rivers, and around God's 

and Island Lakes, Robert Bell, Rept. of Prog. Geol. Survey of Canada for 1878-'79, 

pp. 1-44 C. With a map.

'Report on Hudson Bay and some of the Lakes and Rivers lying to the west of 

it, Robert Bell. Rept. of Prog. Geol. Survey of Canada for 1879-'80, pp. 1-56 C.

6 Report on the Geology of the Basin of Moose River and adjacent country, Robert
VANHISB.] THE GEE AT NORTHERN AREA. 221

Bell. Rept. of Prog. Geol. and Nat. Hist., Survey of Canada for 1880-'81-'82, pp. 

1-9 C. Accompanied by a map.

7 Observations on Labrador Coast, Hudson Strait and Bay, Robert Bell. Rept. of 

Prog. Geol. and Nat. Hist. Survey and Museum of Canada for 1882-'83-;84, pp. 3-37 DD.

8 The Geology and Economic Minerals of Hudson Bay and Northern Canada, Robert Bell. Proc. and Trans. Royal Soc. Canada, vol. n, sec. 4,1884, pp. 241-245.

y Observations on the Geology, Zoology, and Botany of Hudson's Strait and Bay, 

made in 1885, Robert Bell. Rept. of Prog. Geol. and Nat. Hist. Survey of Canada for 

1885 (new series), vol. I, pp. 1-27 DD. With a chart.

10 Report on an Exploration of portions of the Attawapishkat and Albany Rivers, Lonely Lake to James Bay, Robert Bell. Rept. of Prog. Geol. and Nat. Hist. 

Survey of Canada for 1886, (new series) vol. n, pp. 5-39 G. With 4 plates.

11 Notice relative to the Geology of the Coast of Labrador, Rev. Mr. Steinhauer. 

Trans. of the Geological Society, vol. n, 1814.

12 Geological Appendix, Dr. McCulloch. A Voyage of Discovery, for the purpose 

of exploring Baffin's Bay, etc., by Sir John Ross, in 1818. London, 1819, vol. n, p. 141.

13 Appendix I, J. Richardson. Narrative of a Journey to the Shores of the Polar 

Sea in the years 1819-;22, by Capt. J. Franklin. London, 1823, pp. 520-534.

14 Journal of a Second Voyage for the Discovery of a Northwest Passage, etc., 

1821-'23, Captain Parry. London, 1824.

15 Notes on Rock Specimens, Charles Kouing. Supplement to the Appendix to 

Capt. Parry's Voyage for the Discovery of a Northwest Passage in the years 1819-'20, 

(Natural History). London, 1824, p. CCXLVII.

16 A Brief Account of an Unsuccessful Attempt to reach Repulse Bay, etc., Capt. 

G. F. Lyon. London, 1825, pp. 51, 88.

17 Appendix on Geology of Countries discovered during Capt. Parry's Second and 

Third Expeditions, Prof. Janieson. Journal of a Third Voyage for the discovery of 

a Northwest Passage, etc., by Capt. W. E. Parry. London and Philadelphia, 1826.

18 Appendix I, J. Richardson. Narrative of a Second Expedition to the shores of 

the Polar Sea in the years 1825-'27, by Capt. J. Franklin. London, 1828.

19 Narrative of Discovery and Adventure in the Polar Seas and Regions, Sir John 

Leslie, Prof. Jameson, Hugh Murray. Edinburgh, 1830.

20 Appendix on Geology. Narrative of a Second Voyage in Search of a Northwest 

Passage, etc., 1829-'33, Sir John Ross. London, 1835.

al Geological Notice on the New Country passed over in Capt. Back's Expedition, 

by W. H. Fitton. Narrative of the Arctic Land Expedition to the Mouth of the 

Great Fish River and along the shores of the Arctic Ocean, in the years 1833, 1834, 

1835, Capt. Back, Appendix No. 4. London and Philadelphia, 1836.

** Narrative of an Expedition in H. M. S. Terror, 1836-'37, Capt. Back. London, 

1838.

23 Narrative of the Discoveries on the North Coast of America, etc., 1836-'39, Thomas 

Simpson. London., 1843.

24 Narrative of an Expedition to the Shores of the Arctic Sea in 1846-'47, Dr. John 

Rao. London, 1850.

25Arctic Searching Expedition, a Journal of a Boat Voyage through Rupert's Land 

and the Arctic Sea, Sir J. Richardson. London, 1851.

20 On the Geological and Glacial Phenomena of the Coasts of Davis Strait asid 

Baffin's Bay, P. C. Sunderland. Quart. Jour. Geol. Soc., vol. ix, 1853, p. 296.

"Geological Appendix, Sir R. Murchison. The Discovery of a Northwest Passage 

by H. M. S. Investigator, Capt. R. McClure, 1850-'54. London, 1857.

*8Arctic Explorations, Dr. E. K. Kane. Am. Jour. Sci. and Arts, 2d ser., vol. xxiv, 

1857, p. 235.

29 Geological Appendix, Prof. Samuel Haughton. A Narrative of the Discovery of 

the Fate of Sir John Franklin, by Capt. M'Clintock. London; edition of 1859, with 

a geological map. (Appeared first in Jour. Royal Dublin §00., vol, i, 1857, and vol. 

in, 1860.)
222 PKE-CAMBKIAN EOCKS OF NORTH AMERICA. [BULL.86.

30 On the Geology of Labrador, Oscar M. Lieber. Report of the Superintendent of 

the U. S. Coast Survey for 1860, Appendix No. 42, pp. 402-408, accompanied by maps 

and charts.

31 Geology, C. E. DeRance and H. W. Fielden. Narrative of a Voyage to the Polar 

Sea during 1875-'76, etc., by Capt. Sir G. S. Nares, Appendix xv. London, 1878.

32 Notes on some Geological Features of the Northeastern Coast of Labrador, 

Henry Youle Hind. Can. Nat., 2d ser., vol. viu, 1878, pp. 227-240.

33 Appendix III, Prof. B. K. Emerson. Narrative of the Second Arctic Expedition, 

made by C. F. Hall. Washington, Government, 1879.

34 Baffin Land, Dr. Franz Boas. Petermanns Mittheilungen, Erganzungsheft, Nr. 

80, 1885.

35 Three years of Arctic Service, an account of the Lady Franklin Bay Expedition, 

Lieut. A. W. Greely. -New York, 1886.

36 A Summer's Cruise to Northern Labrador, A. S. Packard. Bull. Am. Geol. Soc., 

vol. xx, 1888, pp. 337-363,445-463.

37 Report on an Exploration in the Yukon and Mackenzie Basins, N. W. T., R. G. 

McConnell. Geol. and Nat. Hist. Survey of Canada, Ann. Rept. (new series), vol. iv, 

1888-'89, pp. 1-163 D, with 10 maps.

38 Notes to Accompany a Geological Map of the Northern Portion of the Dominion 

of Canada, East of the Rocky Mountains, George M. Dawson. Ann. Rept. of the 

Geol. and Nat. Hist. Survey of Canada for the year 1886, vol. n (new series), pp. 1-62 R 

R, with a geological map.

39N6tes on the Geology of the North Coast of the St. Lawrence, Capt. Bayfleld. 

Trans. Geol. Soc. of London, 2d ser., vol. v, pp. 89-102.

40 On the Geology of Portions of Lower Canada., both North and South of the St. 

Lawrence, W. E. Logan. Rept. of Prog. Geol. Survey of Canada for 1849-'50, pp. 8-10.

41 On the Geology of the North Shore of the St. Lawrence, between Montreal and 

Cape Tourment, W. E. Logan. Rept. of Prog. Geol. Survey of Canada for 1852-'53, pp. 

5-40.

42 Notes on the Geology of Murray Bay. Lower St. Lawrence, J. W. Dawsou. Can. 

Nat. and Geol., vol. vi, 1861, pp. 138-150.

43 Report for 1869 on the North Shore of the Lower St. Lawrence, James Richardson. Rept. of Prog. Geol. Survey of Canada for 1866 to 1869, pp. 305-311.

44 Report on the Country North of Lake St. John, James Richardson. Rept. of Prog. 

Geol. Survey of Canada for 1870-;71, pp. 283-308.

45 Report of Geological Observations in the Sagueuay Region, Abbe" J. C. K. LaFlamme. Rept. of Prog. Geol. and Nat. Hist. Survey and Museum of Canada for 1882, 

1883,1884, pp. 3-18 D. .* 

46Report on the Mistassini Expedition, A. P. Low. Ann. Rept. Geol. and Nat. Hist. 

Survey of Canada for 1885, vol. i (new series), pp. 1-55 D, with a map.
OHAPTEE IV.

EASTERN CANADA AND NEWFOUNDLAND. 

SECTION I. THE EASTERN TOWNSHIPS.

LITERATURE.

MuKRAY,1 in. 1847, describes the metamorphic rocks of the Notre 

Dame mountains. The more important varieties are slate and trap. 

It is not certain that these rocks do not belong to the fossiliferous formation.

LoG-AN,2 in 1863, describes the Quebec group at length. Metamorphic rocks of various kinds are mentioned, but these are all regarded 

as belonging to the fossiliferous series. In the fossiliferous formations 

east of the Notre Dame mountains are veins and masses of intrusive 

granite.

SELWYN,3 in 1879, gives observations on the stratigraphy of the 

Quebec group. This group is divided into three distinct groups of 

strata. First, the lower Silurian group; second, the volcanic group, 

probably lower Cambrian; and third, the Crystalline schist group 

(Huronian ?). The rocks composing group three are chiefly slaty and 

schistose, embracing various schists, imperfect gneisses, micaceous 

dolomites, and magnesian limestones. The upper part of this series 

emerges from beneath the upper Silurian.

SELWYN, 4 in 1883, finds in the Stoke mountains an igneous belt unconformably overlapped and covered by the fossiliferous beds of the 

Levis formation and by the Siluro-Devonian rocks; but between these 

volcanics and the more schistose rocks of the central axis, by which 

they are underlain, no unconformity has been detected. These volcanics are provisionally classed with the lower series, that is, pre-Cambrian and probably Upper Huronian. In the Quebec series are found 

important masses of granite which are intrusive in th« fossiliferous 

series. The stratified rocks in contact with them are disturbed and 

altered, the limestones converted into graphitic schists or crystalline 

marble, and the argillites into mica-slates, chiastolite and staufolite 

schists, which are traversed by streaks and veins (dikes?) of granite. 

These granites are regarded as of Silurian or Devonian age. The alteration of the fossiliferous beds has gone so far as to suggest a resemblance to the crystalline rocks which have been referred to the Laurentian or Huronian.

223
224 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL.86.

SELWYN,5 in 1883, in further speaking of the Quebec group, asserts 

of the upper metamorphic or volcanic group that neither a schistose nor 

a bedded structure can be accepted as a proof of nonigneous origin, and 

that a massive lava flow is as likely, through pressure and metamorphism, to assume a schistose structure as are ordinary sedimentary 

strata. Much of the material of the upper part of the lower groups is 

of contemporaneous irruptive and eruptive origin, though for the most 

part, through cleavage and alteration, so changed in external and 

physical character as to cause these rocks to be classed as metamorphic, notwithstanding that they still closely correspond in chemical 

composition with recognized igneous and volcanic rocks, and differ essentially from any known ordinary unmixed sedimentary deposits. It is 

suggested that the upper volcanic group may represent the Keeweenian.

ELLS,6 in 1887, reports on the geology of a portion of the Eastern 

Townships. Placed in the Cambrian are a set of slates of various colors, 

sandstones passing into quartzites, quartziferous schists and conglomerates in which are found no calcareous beds or fossils. The conglomerates are of two kinds j one is composed of pebbles of the ordinary kind, 

granitoid rocks, quartzites, slates, etc.; the other is composed largely 

of dioritic pebbles in a diorite paste with intercalated beds of sandstones 

and grits, and may be regarded as an agglomerate. This series in 

places is certainly unconformable to the Canibro-Silurian system on the 

one hand, and in a like manner is unconformable to the underlying 

ridges of crystalline rocks from the d6bris of which they are largely 

formed. These strata for the most part flank the ridges of crystalline 

schists and gneisses, but at other times are in intricately folded basins 

in them. These rocks resemble the gold-bearing series of Nova Scotia. 

When near to or cut by masses of granite the strata have developed in 

them crystals of chiastolite and staurolite.

The areas of crystalline schists, gneisses, and limestones, with serpentines and associated strata are referred to the pre-Cambrian. The age 

of these rocks is inferred from their lithological character, from their 

position of apparent unconformity below the overlying series referred 

to the Cambrian, and from the fact that their debris is found in the 

latter series. The areas of pre-Cambrian rocks are four in number. In 

position, and in the fact that they contain copper, they closely resemble 

the copper-bearing rocks of New Brunswick and the Huronian of Bruce 

mines. There is a similarity to the series in England and Scotland 

described by Hicks under the names of Dimetian, Arvonian, and Pebidian. Summing up it is said: Whatever may be the exact age of these 

altered rocks, their present aspect entitles them to be classed as very 

ancient sediments, although, in view of the great alterations which 

may result from intense regional metamorphism, there is no reason why 

many of the ordinary sedimentary rocks of Cambrian, Cambro-Silurian, 

or even Silurian age, should not assume much of the character of these 

just described. It is now tolerably clear that the series now considered
U.S.GEOLOGICAL SURVEY. BULLETIN 86. PL V.

UNCLASSIFIED PRE - CAMB. ALGONKIAN ALGONKIAN?

GEOLOGICAL MAP OF NEW BRUNSWICKMOVA SCOTIA, AND PART OF QUEBEC

SHOWING PRECAMBRI ROCKS

Complied from official maps of 3 Canadian Geol. Survey 

Scale 43o5oo.

POST-ALSONKIAN ____ERUPJIVES____ 6RAN1T1C BASIC^
VAN HISB.] EASTERN CANADA AND NEWFOUNDLAND. 225

constitutes the lowest of all the geological formations encountered in 

this portion of the province.

Both plutonic and volcanic rocks occur in the Eastern Townships, including- granites and diorites, .some of which are at least as late in age 

as the Lower Silurian, although others are earlier, as is shown by the 

fact that fragments of them are included in the strata referred to the 

Cambrian. The sedimentary strata are altered at the contacts with 

these intrusives. These granites are, however, held by Selwyn to be 

metamorphic.

SELWYN, : in 1887, states that at the Bras stream, about 3 miles from 

the Chaudiere river, is well exposed a contact of the crystalline series 

with the black slates, showing the same imconforrnable relations 

between the Cambrian and pre-Canibrian as on the Quebec Central 

railway. The granites considered by Ells as intrusive are regarded as 

mare probably formed in situ by the same metamorphio agencies that 

have altered the adjacent strata, and the so-called dikes are probably 

due to segregation; in fact, the latter are rather veins than dikes. 

The granites arc then regarded as an effect of the metamorphosing 

agencies rather than the cause of the metamorphisin.

ELLS,B in 1889, gives a second report on the geology of the Quebec 

group. Throughout the area of the rocks referred to the Lower Cambrian no fossils have yet been found, but they resemble the lower portion of the Cambrian of New Brunswick. The most that can be said of 

them stratigraphically is that they are intermediate between the chloritic and micaceous schists of the central anticlinal and the overlying 

rocks of the Sillery. These Cambrian rock's have certain beds which 

closely resemble those of the, Potsdam age of the Sillery; on the other 

hand, it is not easy to separate them from the underlying pre-Cambrian 

schists, although at certain points there is a manifest unconformity 

between the two series, as is well shown between Broughton station 

and Harvey hill on the Quebec Central railway; the regular strike of 

the underlying chloritic rocks being nearly east and west, Avhile the 

overlying black slate, with which are associated beds of grayish limestone, at times strike nearly north and south. The difference in the 

character of the Cambrian and pre-Cambrian strata, together with the 

fact of the occurrence of a line of fault between the crystalline schists 

of the Button mountain anticlinal and the slates and serpentines to the 

cast, are the chief reasons for the separation of these two series into preCambrian and Cambrian. The pre-Cambrian areas found arc composed mostly of alternations of chloritic and micaceous schists. In 

certain localities, as at Lcs Saints Anges, are found micaceous black 

and gray slates, and quart/ites'with crystalline limestone, which may 

be Cambrian or pre-Cambrian. The areas of granite, diorite, and serpentine are described.

ADAMS, 9 in 1880, finds that the massive and stratified varieties of 

the anorthosite underlying the northwest part of the Eastern Townships 

Bull, 86 15
226 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. (BUU.M.

are really only different portions of one and the same mass. It is concluded that most, if not all, of the areas are of eruptive origin, since 

they are frequently found cutting the gneisses. Bands of crystalline 

limestone are found in the region.

ELLS,IC in 1890, states that the lowest beds of the Lower Cambrian 

frequently contain a very considerable thickness of conglomerates, the 

pebbles of wliich are without doubt derived from the underlying crystalline ridges Avhich have been called pre-Cainbrian. They are distinct 

in character from the pre-Oambrian of the anticlinals, the latter being 

in all cases highly crystalline, while there is a sharply defined line, 

either of imconformable overlap or of fault, between the crystalline 

series and the slates and qnartzites of what has been styled Lower 

Cambrian. This line of fault is to be seen at certain points, and is 

heavy; at others the slates occupy basin-like areas infolded in the 

schists, Avhere the rocks pass at once from the black, gray, and purple 

slates to the highly altered schists. There are certain areas of micaschists and black slates which are apparently in the center of the 

anticlinal of Sutton or the Chaudiere. These probably represent a 

portion of the pre-Cambrian, but they are quite distinct from the ordinary black, purple, and gray slates and quartzites of the Chaudiere 

gold series.

SUMMARY OF KESULTS.

A large number of articles have been written in reference to the 

Quebec group which are not touched in the above, as their point of 

view is paleontological, aud°if the crystallines are referred to at all they 

are simply placed as the metamorphosed equivalents of the fossiliferous 

rocks.

While Ells places the middle series found in this region as Cambrian, 

he is very cautious to say that he has no paleontological evidence for 

this; so that it is yet to be considered an open question whether it is 

Algonkian or not. By Selwyn it is compared with the Keweenawan, 

and by Ells with the Nova Scotia gold-bearing .slates. It is certain that 

the series is uncomformably below the Potsdam, and equally certain that 

it overlies crystalline schists. While' the so-called Cambrian and preCambrian are said to be unconformable, and several localities are cited in 

which these relations obtain, one wishes that they had been described in 

more detail. The only one mentioned in which the facts are given upon 

which the statement of uncomformity is based is the one on the Quebec 

railway, where it is said that the strike of the Cambrian slates is almost 

at right angles to that of the pre-Cambriau schists. When it is remembered that there probably are in this region great masses of intrusive 

granites which have metamorphosed the adjacent strata, and that as a 

result of such action a schistose structure oftentimes develops independent of the original bedding, the evidence cited at this particular 

locality is by no means sufficient to establish the conclusion. However,
vANHtsB.] EASTERN CANADA AND NEWFOUNDLAND. 227

the basal couglomerates of the series referred to the Cambrian, the crystalline character of the pre-Oainbrian as contrasted with the clastic 

character of the Cambrian, and the sharply denned line, either of uncomformable overlap or of fault, between the crystalline series and the 

slates and quartzites which are styled Lower Cambrian, indicates the 

probability that a structural break of great magnitude does occur between the two series. The supposed lower series of crystalline chloritic 

and micaceous schists and gneisses, with their associated quartzites 

and limestones, seems clearly to be of clastic origin. It is compared 

with the Huroniaa by Ells. From present imperfect knowledge it can 

only be safely placed as Algonkian. If it shall turn out that the uonfossilit'erous rocks referred to the Cambrian by Ells are also Algonkian, 

this system is represented in the Eastern townships by two series which 

are probably uuconiforniable,

Selwyn's later position as to the nature of the granite is the opposite 

of that earlier held. In his reports published in 1879 and 1883 the 

granites are not only believed to be intrusive, but many of the crystalline schists are believed to be metamorphosed irruptives. In the footnotes accompanying Ells's reports these same granites are said to be 

metamorphi(f.

SECTION n. GASPE" PENINSULA.

LITERATURE.

ELLS,U in 1885, describes the pre-Cambrian rocks of the Gasp6 

peninsula. These are confined to the Shickshock mountains. They 

are garnetiferous gneiss, homblendic, chloritic and micaceous schists, 

epidosite, etc. These rocks are so like the pre-Cambrian as seen in 

New Brunswick and other parts of Canada that they are removed from, 

the Quebec group and assigned to an older horizon. Serpentines, diorites, and granites are mtrusives, a part of them later in age than 

Devonian,

Low,12 in 1885, also describes the pre-Cambrian rocks of the Gaspe" 

peninsula. They are represented by the metamorphic schists and 

slates of the Shickshock mountains, among which are serpentine, and 

several beds of limestone, one of them being 90 feet thick. Great 

masses of granite and dikes of trap are found in these series. The 

granites are evidently of later date than the Silurian and Devonian 

rocks, as fragments of these are inclosed in them, and the adjacent 

stratified rocks show alteration.

SECTION III. CENTRAL NEW BEUNSWICK.

LITERATURE.

EOBB, 13 in 1870, gives a report on the geology of central New Brunswick. The crystalline rocks include (1) a band of metamorphic rocks 

immediately underlying the Carboniferous series and extending to the
228 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. |BULL. 86.

southeastern boundary of the great granite area, (2) the central 

granite area, (3) a band of noncalcareous metamorphic slate and 

quartzite lying immediately northwest of the granite area. The southern slate band extends from Magaguadavic lake to the southwest Mirauiichi, its breadth varying from 9£ miles on the St. John river to 17 

miles on the Mirarnichi. The rocks consist of argillaceous and micaceous clay-slates, with interposed bands of crystalline, quartzose, micaceous and feldspathic rocks resembling sandstone. They are doubtless 

altered sediments. In one place apparently in this series are fossils, 

probably of Upper Silurian or Devonian age. The central granite occupies a considerable area to the northwest of the slates. The line 

between the slates and granite is somewhat arbitrary, for the slate and 

quartzite band includes three very considerable, with some smaller, 

bauds of granite. The various feldspathic rocks of the region seem to 

merge into each other. This is true, not only of the granite and gneiss, 

but even of the foliated semicrystalline slates and quartzites. Occasionally fragments of gneiss of all shapes and sizes are found imbedded 

or incorporated in the granite, and vice versa; but no appearance of 

granite veins cutting the laminated rocks are noted. The slates, micaschists, and quartzites of the northern slate belt locally assume a crystalline aspect. Bauds of crystalline rocks resembling granite, syenite, 

and diorite are intercalated in the manner of conformable or interbedded masses. At one place is found a slate-con glomerate which is believed 

to occupy a depression in the older rocks.

RoBB, 14 in 1872, gives some additional facts in continuation of his 

studies. The central granite area is divided into two granitic bauds. 

Much of the granite area is of a gneissoid character. Where the change 

from granite to slate occurs, the granite near the line of contact is 

often of a red variety and rather fine grained, gradually passing into 

the ordinary color and texture in receding from the line. All attempts 

to elucidate the structural relations of the granite have proved futile. 

In the slate band northwest of the granite are conformable dikes of 

diorite, syenite, and other feldspathic rocks. Immediately at the juuc: 

tiou of the granite with this series is a band of pure crystalline limestone.

ELLS,15 in 1881, reports on the geology of northern New Brunswick. 

The pre-Cambrian rocks are believed to underlie uncouforniably the 

Cambro-Silurian. The typical rock is a grayish feldspathic gneiss, 

frequently containing hornblende. The rocks referred to the pre-Oambrian include granites, felsites, gneisses, and schists. Grani tes, diorites, 

dolerites, and felsites are found. A portion of these are'mingled with 

the pre-Canibrian, but others, and especially tlie basic eruptives, are 

found in the slates and other rocks belonging to the fossiliferous series. 

At the contact of the granites Avith the slates in places the latter 

become crystalline and contain crystals of staurolite.

ELLS,IS in 1883, finds crystalline mica-schists, quartzites, etc., which
VANHISE.] EASTERN CANADA AND NEWFOUNDLAND. 229

are provisionally referred to the pre-Cambrian system. They are found 

at two places conformably to underlie the Canibro-Silurian series.

BAILEY/ 7 in 1885, in a report on York and Carleton counties in central New Brunswick, finds no rocks which are regarded as pre-Cambrian; but granites, syenites, basalts, and diabases occur which are 

regarded as intrusive. Interstratified with the Lower Carboniferous 

are beds of volcanic or semi-volcanic origin. The granite is filled with 

imbedded fragments of other rocks, so that in places it has the appearance of a conglomerate. Beyond question they come from the schistose 

and micaceous rocks which border the granite, as is shown by their 

identity in character with these rocks. Also the lines of contact show 

the intrusive character of the granite.

BAILEY,18 in 1880, in continuing his work in central New Brunswick, 

finds highly crystalline strata, including gneisses, syenites, and felsites, which are referred to the pre-Cambrian. They are thought to be 

a continuation of those described by Ells. In this pre-Cambrian aro 

included without doubt very considerable masses of igneous rocks.

BAILEY and MolNNES, 19 in 1877, in continuing work on central New 

Brunswick find felsites, quartzites, and mica-schists, which are referred 

to the pre-Cambrian. Only the boundaries of the rocks are mapped, no 

attempt being made to work out the structure. These rocks are cut by 

granites which are found in two areas. These granites are the same 

character as those which have been previously described as of probable 

Devonian age.

SUMMARY OF RESULTS.

As a result of the above work in central New Brunswick it is clear 

that below the Cambro-Silurian rocks is a set of semicrystalline and 

crystalline schists containing among °the former such rocks as slate, 

quartzite, and limestone. The character of these is such as to show 

that they are in part of clastic origin. Large masses of intrusive rocks, 

both basic and acid, cut both these rocks and the fossiliferous sedinientaries. The masses a.re sometimes so large as to cause important 

contact metamorphism.

There is little difficulty in separating the intrusives from the fossiliferous rocks, but upon account of the more crystalline character of the 

older series and its likeness in mineralogical composition to certain of 

the subsequent iutrusives, and further, upon account of the intimate 

mingling which occurs between these two classes of rocks, it is difficult 

to make the separations with the same degree of sharpness. This dim1 - 

cnlty is not improbably further increased by the presence of intrusives 

earlier than those which cut the Cambro-Silurian rocks.

The maps presented of the pre-Cambrian are purely.areal, no attempt 

whatever being- made to subdivide them or to work out their structure.
230 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL.86.

SECTION IV. SOUTHERN NEW BRUNSWICK.

LITERATURE.

GESNER,20 in 1839, gives many details as to particular localities in 

southern New Brunswick. The succession of rocks below the Old Eed 

sandstone is argillaceous slate and granite. The volcanic rocks of the 

bay of Fundy are of different ages.

GESNER,21 in 1.840, gives a continuation of his study of the previous 

year.

GESNER,22 in 1841, describes the geology of the county of St. John 

more fully than in previous reports. The syenites occupy a large area, 

and against these lean the slates, graywackes, and limestones parallel 

to the coast of the bay of Fundy, but there is a group of more schistose 

rocks containing no organic remains which dip toward this ridge. 

These latter are evidently primary, white the graywackes and graywacke-slates are Cambrian or Silurian. It is certain that a part of the 

granitic and syenitic rocks which have been regarded as primary really 

.belong to a later age.

GESNER,23 in 1842, finds that the graywackes and slates provisionally 

correlated with the Cambrian were deposited prior to the elevation of 

the granitic, syenitic, and trappean masses upon which they rest, as 

they are fractured in all directions by dikes and extensive elevations 

of those rocks.

GESNER,24 1843, places the granite, syenite, trap, and serpentine in 

the unstratified rocks. To the Cambrian system are referred a series 

of graywackes and clay-slates which are sometimes conglomeratic. 

These rocks extend from, the American boundary to near Bathurst, 

and ia them organic remains occur.

JoHNSTON,25 in 1850, iu a report on the province of New Brunswick, 

gives a map by Eobb in which the crystalline rocks are outlined as 

granite, gneiss and mica-slate, and trap rocks.

BAILEY, MATTHEW and HARTT,26 in 1865, in observations on the geology of southern New Brunswick, give a resume of the Avork previously 

done. Of the 15 different groups of rocks, the lowest consists principally of granite, gneiss, mica-schist, and thick beds of crystalline limestone. This is the Laurentiau or Portland group. Besting upon the 

Portland group is the Coldbrook group, belonging to the Huronian 

division of the Azoic system, and thick deposits of altered slate of a 

volcanic character, surmounted by conglomerates. The Coldbrook 

group is succeeded by the St. John group, which contains no coarse 

material and is regarded as equivalent to the Potsdam or Primordial 

of New York. Above the St. John group is the Bloomsbury group of 

volcanic character, such as basalt, amygdaloid, and trap rock, which 

are associated with conglomerates and slates destitute of fossils. Geographically separated from the above groups are the rocks of Kingston, 

which are regarded as tipper Silurian, and the mica-schists of Queens
T EASTERN CANADA AND NEWFOUNDLAND. 231

county, which may be Cambrian. Scattered through all the above are 

igneous rocks such as granite, syenite, porphyry and trap, which may 

occur associated with rocks of any age. The Portland group is in almost entire conformity with the Ooldbrook group. The lithological resemblance of the Coldbrook group (7,000 feet thick) with the Huronian 

is very close. The presence of graphite in the Portland and St. John 

groups is regarded as evidence of life.

The extreme metamorphism of the Portland group is evidence of its 

great antiquity. This age would never have been doubted were it not 

for the intimate association and conformability with the beds of the 

overlying groups, which are unquestionably Tipper Devonian, and the 

Portland was supposed to represent either a portion of the Lower Devonian or possibly the upper part of the Silurian. During the deposition 

of the Azoic and Silurian ages a long period of repose prevailed, broken 

only by the volcanic activity of the Coldbrook group. The Bloomsbury 

rocks associated with rocks unquestionably of Upper Devonian age 

are referred to the same horizon. At one place the Coldbrook group 

overlies the St. John, its position being due to a reverse folding caused 

by a ridge of eruptive syenite. The Kingston group on its general 

lithological character and stratigraphical relations is provisionally referred to the Upper Silurian, although Lower Silurian and Lower 

Devonian beds may occur.

MATTHEW,27 in 1865, correlates the Portland series, which includes 

limestone, syenite, gneiss, conglomerate, slate, and graphitic shale, with 

the Laurentian, first, because of its lithological characteristics, and 

second, because it is unconformably overlain by great thicknesses of 

deposits similar to the Huronian series of Canada. The Coldbrook 

Huronian group is conformable with the Lower Silurian St. John beds, 

although there is a marked contrast between the formations, the former 

containing conglomerates and volcanic products, but the latter none.

HiND,28 in 1865, in a geological sketch of the province of New Brunswick, finds no rocks older than the Lower Silurian. The belts of granite are regarded as of Devonian age, being apparently thrust up through 

the Lower Silurian and Devonian strata before the beginning of the 

Carboniferous epoch. The Quebec group includes gneiss, anorthosite, 

mica-schist, hornblende rocks, diorite, various schists, and other crystalline rocks. ^

MATTHEW and BAILEY,29 in 1870, divide the metamorphic rocks of 

New Brunswick and Maine into, first, a Laurentian series, which consists of gneiss, often granitoid in aspect, including (1) crystalline limestone and interstratified beds of quartzite and diorite, (2) a Labradorian or Upper Laurentian series, which consists of feldspar rock 

associated with hypersthene and magnetite; and, second, a Cambrian or 

Huronian series. The granites of St. Johns river are of Devonian age.

 BAILEY and MATTHEW,SO in 1872, find the Laurentian system to have 

a rather widespread distribution. The rocks are placed in the Lau-
232 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BOTX.OT.

rentlan because older than the Silurian rocks, which contain a Primordial zone, as Avell as on account of their general lithological resemblance 

to the ancient rocks of the Laurentian system. The Laurentian is 

separated from the Primordial beds by an accumulation of trappean 

and tufaceous strata which is supposed to be of Huronian age. The 

lower division of the Laurentian consists of diorites, syenite, granitoid gneiss, etc., while its upper division consists of crystalline limestone with diorite at intervals, greenish gray gneiss, quartzite, argillite, 

and slate conglomerate. The contact of the granite with the schistose 

rocks is peculiar. Contained in the granite are long irregular blocks 

of the schistose rock. Their occurrence suggests either a softening of 

the older series through metamorphism subsequent to the deposition of 

the upper series, or else the intrusive character of the granites. One 

section of gneiss and granite in the Lower Laurentian has a thickness of 12,600 feet. The maximum thickness of limestone and quartzite 

of the Upper Lanreutian is not more than a thousand feet.

In the Huronian series are placed the Goldbrook, Coastal, and Kingston groups, which together occupy a wide area. The Coldbrook group 

at several points was observed to rest upon the gneissic and granitic 

rocks referred to the Laurentian system, and in turn to be conformably 

overlain by the slates of the St. John group containing Primordial 

fossils. The Coldbrook group consists of diorite, chlorite-schists, black 

slates, micaceous shales, argillites, gneissoid rocks, and other varieties. 

The rocks of the Coastal group consist of felsites and conglomerates, 

gray limestones, and gray clay slates, gray chloritic grits and schists, 

micaceous slate and gray dolomite, green and red clay slate, and diorite. 

The Kingston group consists of shales, felsites, diorites, and argillites. 

In Grand Manau are various crystalline rocks which are not definitely 

referred to any period, but are compared to the Huronian. The Devonian and Huronian rocks are iblded together, but no evidence is seen of 

unconformity between the two series. The Mascarene series in general 

aspect resembles the Huronian series of St. John and King counties. 

Intrusive granites are found at many points. In general the contacts 

of these granites with the surrounding rocks are not found, and their 

age is thus unknown.

The diorites and schists of Bloomsbnry mountain, formerly supposed 

on stratigraphical grounds to be more recent than the Huronian, resting 

upon the St. John group and overlain conformably by the Devonian 

sandstones, are now regarded as Huronian on lithological grounds, 

being probably brought up by a fault. At Musquash harbor "and at 

liatclifte's mill stream green suberystallme schists rest conformably 

upon the Primordial strata, but these are believed to be overturns and 

the former Huronian.

The rocks of the Coastal group at several points overlie Upper 

Silurian or Devonian strata. They were formerly described as Devonian^ but as Hunt iinds them similar to the Huronian in lithological
VANIUSK.] EASTERN CANADA AND NEWFOUNDLAND. 233

character, they are here referred, and the. apparent inferior position of 

the Devonian is supposed to be due to a dislocation. Accidental intercalations of Upper Silurian and Kingston strata are found.

BAILEY, 31 in 1872, describes the rocks of the greater part of Grand 

Manan as consisting of Triassic trap. Upon its east side are, however, 

found metamorphic rocks, which may belong to different seriesj but 

none are believed to be more recent than the earliest Primordial 

Silurian, while some of them may be Hurouian.

MATTHEW and BAILEY,32 in 187G, place the Mascareue and Kingston 

series, the latter of which was previously considered Upper Huronian, 

in the Upper Silurian upon account of fossils discovered in them.

BAILEY and MATTHEW,33 assisted by Ells, in 1877, in observations 

on southern New Brunswick, provisionally refer the Coldbrook group, 

formerly considered as Laurentian, to the Huronian. The granites are 

separated from the stratified formations of the Coldbrook group.

MATTHEW,34 in 1878, refers as doubtfully belonging to the Laurentian 

the slate formation of Charlotte county, formerly described as Coastal 

rocks and placed in the Huronian. In the Kingston series, more recent 

than the Coastal, are rather crystalline rocks which are believed in part 

to belong to the Upper Silurian, but, like the Coastal rocks, are of uncertain age. The crystalline mica-schists, hornblende-schists, gneisses, 

diorites, etc., of Grand Manan combine in characters the two belts of 

Kingston rocks and those of certain Upper Silurian strata.

BAILEY and ELLS,35 in 1878, find in the Caledonia mountains of Albert 

and Westmoreland counties chloritic and talcose slates associated with 

beds of grit and conglomerate, which are regarded as probably of Huronian age.

ELLS,:IG in 1879, finds in Albert, eastern Kings, and St. Johns counties 

pre-Silurian rocks, which are placed in the Huronian and Laurentian. 

The older series is said to consist of syenite, felsites, feldspathic quartzites, 

and limestones. In many places are transitions from the slates through 

schists, felsites, and gneisses, to syenites. The newer series consists 

of felsitic, siliceous, brecciated, and ash rocks at the base, with talcose, 

chloritic, and older schists, ash rocks and purple grits, and conglomerates. The second group lies unconformably upon the rocks of the first.

BAILEY, 37 in 1879, divides the pre-Silurian rocks of southern New 

Brunswick into four divisions on lithological grounds. The first are 

syenitic, feldspathic, and gneissic rocks; the second, limestones and 

dolomites, with others. These two divisions are regarded as belonging 

to the Laurentian. The third is a felsite-petrosilex group which comprises sandstones and conglomerates, as well as amygdaloidal ash rocks 

and ash conglomerates. This is the Coldbrook group of the earlier reports and is regarded as a lower member of the Huronian system. The 

fourth division is a schistose, chloritic, and micaceous group, comprising 

among other rocks conglomerates, clay slates, quart/ites, ash rocks, 

ainygdaloids, etc*, and is regarded as the upper member of the Huro-
234 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. \rnni. m.

nian system. The passage from division 2 to division 3, that is, from the, 

Laurentiau to the Huronian, is a gradual one, as the two groups are 

intimately associated.

Placing the Upper Ooldbrook group as pre-Silurian, the uneonformability of this group with the Silurian is marked in general. The Primordial beds sometimes rest upon divisions and sometimes upon division 

4, they contain in places coarse basal conglomerates, and appear to have 

been originally deposited among the hollows of the Hurouian series. 

South of Bloomsbury mountain, and on the main stream of Black river 

and the adjacent region, the Huronian rocks are associated with the 

Devonian, and the two formations accord almost exactly both in strike 

and dip, the Devonian being included among the Huronian rocks. But 

in addition to the fact that the conglomerates of the former are largely 

made up of the debris of the latter, there are points in which this accordance is clearly wanting. The discordance is pretty well seen at the 

east branch of Black river.

MATTHEW,38 in 1879, finds the Kingston series to exhibit a strong 

resemblance to the Huronian formation of St. John county, but it is regarded as Silurian on paleontologieal grounds.

BAILEY, MATTHEW, and ELLS," in 1880, give a general review of 

their work done upon southern Xew Brunswick, which covers an area 

of about 6,000 square miles. The rocks comprised under the pre-Cambrian include the Laurentiau of 1871 and the three former divisions of 

the Huronian-Coastal, Coldbrook, and Kingston. Of the relations of 

the upper members of the Laurentian mica-schist, limestone, and fine 

gneiss, to the main body of coarse .syenite and syenitic gneiss constituting the Lower Laureutian, nothing further is known than contained in 

the report of 1870-'71. The greatly broken and disturbed character of 

the supposed upper series, the obscure stratification of much of the 

underlying group, and the frequent occurrence of intrusive masses, 

combine to make the determination difficult. There can, however, be 

no question that the bulk of the calcareous and siliceous strata are more 

recent than the coarse granitoid rocks with which they are associated. 

With one possible exception, no instances of direct superposition of the 

Coldbrook rocks on the Laurentian have been observedj but the 

Coastal rocks are found upon the Coldbrook rocks as well as upon the 

Upper Laurentian, so there is no reasonable doubt as to the true succession. Contacts of the Coastal group with the Coldbrook group are 

found in the county of St. John, and especially along the line of the St. 

Martins and Uphain railway, between Upliam and Quaco, and on the 

lower Quaco road on either side of Bloomsbury mountain. In passing 

from one to the other there is often an abrupt change of dip, the beds 

of the higher series dipping at a lower angle than those upon which 

they rest, while along the same line of contact it is not uncommon to 

find masses of coarse breccia conglomerate, in which the fragments are 

largely the petrosilex derived from the inferior group. It is, however,
YAK HIM.] EASTE11N CANADA AND NEWFOUNDLAND. 235

questioned whether the uncoiiforinability is sufficient to prove the fact 

of any considerable lapse of time. The age and equivalency of the 

Kingston group, as well as that of the Mascarene peninsula, is somewhat uncertain, owing to the difficulty of obtaining stratigraphical evidence and from the close resemblance which many of them bear on the 

one hand to the rocks of the Huronian, and on the other to those of the 

Silurian.

BAILEY,40 in 1881, in summarizing the work of the survey in New 

Brunswick, concludes that there is a Laurentian and Huronian, as in 

other parts of Canada. These are below the Primordial by a marked 

unconformity. These rocks east of St. John occupy irregular troughs 

in the pre-Silurian rocks, resting sometimes upon one and sometimes 

upon another of the subdivisions of the latter, crossing their strike 

obliquely and having coarse basal conglomerates. There is almost perfect lithological likeness between the great mass of rocks referred to 

the Laurentian, including coarse and fine grained gneisses, quartzites, 

graphitic, and serpentinous greenstones and dolomites, with the Laurentian of other parts of Canada, and particularly the Hastings series of 

Yennor. This series is capped by the great volcanic series of the Huronian. These pre-Silurian rocks are confined wholly to the region of 

the southern metamorphic hills, nothing of equivalent age having yet 

been identified in the central and northern portions of the province. 

In the rocks referred to the Huronian are two well marked divisions, 

the lower or Coldbrook group and the upper or Coastal group, between 

which there is not infrequently evidence of at least a partial unconformity. The pre-Silurian rocks are of vast thickness 5 their divisions 

were deposited under markedly different conditions; there are unconformities between these divisions. These facts show that these rocks 

are at least as old as the Huronian and portions of the Laurentian system. Above the Upper Silurian rocks are found felsite-porphyries and 

peculiar orthophyres at Passamaquoddy bay, and at Eastport and 

Pembroke, Maine. On the.St. John river, associated with the fossiliferous rocks are amygdaloidal and ash rocks which are indistinguishable lithologically from the Huronian formation, and to which all of 

these rocks have previously been referred.

BAILEY,41 in 1885, finds the granites of southern and central New 

Brunswick to be of intrusive character and to cut rocks as late iu age 

as the Carboniferous. As evidence of this are cited the abrupt transitions from the massive granite to the associated schists; the widely 

different characters of the invaded beds; the fact that foliation and 

crystallization are most marked in the vicinity of the granite and decrease in receding from it; the outlines of the granite are irregular and 

sometimes parallel, at other times are oblique to, and at other times 

at right angles to the rocks cut; detached masses or bosses of granite 

border main granitic areas; granite veins like those of the main, mass 

of granite penetrate the schists in all directions adjacent to the granite
236 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BUU.SG.

large detached blocks of schists and gneiss, usually angular, 

are frequently contained in the granite, sometimes being so abundant 

as to produce the appearance of a coarse breccia. As to the age of 

these granites, no veins are found penetrating later strata than the 

Upper Silurian, but all conglomerates older than the Lower Carboniferous are destitute of granite pebbles, while the later formations abound 

in them, which appears to indicate that the granites are Devonian.

ELLS/2 in 1886, finds in Albert county pre-Oambrian rocks which include quartzite, felsite, gneiss, syenite, and granite. The crystalline 

limestone rests generally upon the flanks of the schistose series. These 

rocks are an eastern extension of the pre-Cambrian of western New 

Brunswick.

BAILEY,43 in 1890, says the evidences of unconformity between the 

Primordial and Archean are clear, varied, and widely distributed. It 

is equally evident that the Archean consists of two groups of sediments, 

which in many features resemble the Laurentian and Huronian systems of Canada; butthere are equally striking differences between the 

supposed Laurentian rocks of St. John and those of Canada. This is 

especially marked by the greater proportional amount in the former of 

distinctly stratified rocks, such as slates and quartzites, and the absence 

of coarsely crystalline deposits. As regards the Huronian rocks, the 

greater part were referred to as felstones, clay-stones, porphyries, and 

petrosilex before the introduction of the present methods of petrographical research and their names in some instances are probably misapplied. 

The relations of the Laurentian and Huronian systems are not well 

understood. While the author does not doubt that the clastic and 

schistose rocks referred to the Huronian are more recent than the granitoid gneissic and crystalline limestones regarded as Laurentian, a contrary view has been taken by others.

MATTHEW," in 1890, states that in the upper Laurentian of New 

Brunswick fossils occur at three horizons. The oldest of these is in a 

quartzite in the lower half of the system. This contains Hexactiuellid 

spon ges, allied to the genus Cyatliospongia. The second horizon is in the 

upper limestone. It contains calcareous coral-like structures which 

bear a resemblance to Stromatopora rugosa. The third horizon is that 

of the graphite beds, in which occurs great numbers of sponge spicules, 

arranged in parallel sets, one set crossing the other at an acute angle. 

The type of sponge is apparently Monactinellid. Eozoon also occurs in 

the Laurentian. Between the upper Laurentiau system and the basal 

Cambrian occurs a third system of rocks, the Coldbrook and Coastal, 

which has given conglomerates to the Cambrian and has a great thickness.

SUMMARY OP RESULTS.

While the mapping of the province of New Brunswick has been completed by the official survey, the statements of the later papers of those 

wbo have taken the most active part in this mapping make it certain
VANHISE.] EASTERN CANADA AND NEWFOUNDLAND. 237

that many of the supposed conclusions reached in the early reports are 

open to doubt. The most noticeable feature is the failure to subdivide 

the Huronian into two or three series on these maps when the divisions 

Coldbrook, Coastal, and Kingston have been found in the reports for 

many years. The reason assigned on the maps for this is that the three 

series are so intimately intermixed that their separation Avdth any approach to accuracy is impossible.

The difficulty of the geology of this region is shown by the manner 

in which these groups have been shifted from one place to another. In 

the days of the earlier work none of them were regarded as pre-Cambrian, and a portion was given as high a place as the Devonian. Thc« 

Kingston group in 1865 was called upper Siluriairand Avas regarded as 

overlying the St. John; in 1872 was called upper Huronian; in 1876 

was again placed as Silurian; and was not until 1879 finally placed 

with the upper Huronian. The Coastal group, first placed in the fossiliferous series, in 1872 was placed in the middle Huronian; in 1878 

was doubtfully referred to the Laurentian, and in 1879 was again returned to its place as middle Huronian. The Coldbrook group has 

been reckoned as Huronian since 1865.

At the outset, in discussing the results attained as to the succession 

of crystalline rocks, the intrusive character of a very large part of the 

granite at a period later than pre-Cambrian time may be considered as 

demonstrated. To this conclusion all the official geologists have agreed 

with the exception of Hind, whose work was done at a time in Avhich 

the metamorphic theory had extreme power. Announced by Gesner in 

1841, the evidence cited by him for the intrusive character of the granite is in a measure the same as that so convincingly given by Bailey 

over forty years later, in 1884.

The plainly eruptive character of a part of the granite suggests the 

question as to Avhether the great mass of syenite, granite, and gneiss 

making up the lower Laurentian is not also of an igneous character. 

Even if this be so, it does not follow that it is not the most ancient rock 

in southern NCAV Brunswick; but the possibility is suggested that it 

may be an iutrusiA^e of a much earlier age than those Avhich cut the 

Silurian strata, and yet not be earlier than a portion of the crystalline 

rocks of clastic origin and pre-Cambrian age.

It is evident that among the rocks referred to the Laurentian of 

southern !SreAv BrunsAvick is a great series of completely crystalline 

rocks, and an apparently unimportant series composed of slates, quartzites, and limestones. This is shown by the estimated thicknesses given 

in the report published in 1872. The lower Laurentian is given a 

thickness of over 13,000 feet, Avhile the upper Laurentian (elastics) have 

a thickness not to exceed 1,000 feet.

The suggested intrusive character of the loAver Laurentian is made 

more probable by the fact that there is said to be transitions between 

these plainly clastic rocks and the thoroughly crystalline ones. Upon
238 PRE-CAMBRIAN BOOKS OF NORTH AMERICA. [BOLL. 86.

the other hand, it is also a possibility that there is a physical break 

between the elastics and crystallines of the Laurentian, but no fragments of the underlying series are found in the elastics nor is any structural unconformity mentioned. One is at once struck with the parallelism between the two parts of the Laurentian of southern New Brunswick 

and those of the Hastings series. In this latter case Vennor, in his later 

work, came to the conclusion that the clastic series is a newer unconformable one resting upon an older crystalline series.

The Laurentian and Huronian are in general said to be in conformity. 

While this is true, Matthew in 1865 states that the Portland series is 

unconformably overlain by the Huronian, and Ells repeats this statement in 1879. In 1880, however, this position is apparently abandoned j 

at least it is not alluded to in the general summary of conclusions. As 

the Huronian and Laurentian are regarded as conformable, the basis 

for separating the clastic series at the base of the Ooldbrooks must be 

considered wholly lithological. It is somewhat difficult to determine 

the lithological criteria used in the distinction, but it seems that the 

appearance of abundant volcanic material is the most important of 

these. Also connected with this fact is a prevailingly darker color. 

When it is remembered that volcanic outbreaks are often of a local 

character, and that it is wholly possible that quartzites and slates are 

being deposited at the same time volcanic accumulations are occurring, 

it must be concluded that the criterion of volcanic activity is an uncertain one. It would seem that it would be more reasonable, without 

reference to other localities, to make the major break above the crystallines of the Lower Laurentian.

The only physical break.finally maintained in the whole pre-Cambrian series is between the two divisions of the Hurouian, the Goldbrook and Coastal. From the descriptions it seems that this break 

is a very considerable one; for detritus of the lower series is contained 

in the upper, and more important than this, the lower series has a 

steeper inclination. Such a break as this certainly implies not only an 

erosion interval, but an orographic movement, and this must mean a 

rather important time break.

Throwing aside all correlations with "other regions and considering 

the pre-Oambrian succession in southern New Brunswick alone, it is as 

follows: (1) Wholly crystalline granites, gneisses, etc. (2) Quartzites, 

slates, slate conglomerates, gneisses, and crystalline limestones. (3) 

Volcanics and elastics of the Ooldbrook. Unconformity. (4) Coastal 

and Kingston groups. While in the reports it is positively stated that 

the Coldbrook is lower than the Coastal and Kingston, even this conclusion apparently can not be taken without question, since the distinction is abandoned in the mapping. The dropping of the term 

Huronian for the post-Laurentian groups indicates that this correlation 

with Huronian, taken for granted for many years, is also considered an 

open question.
VANHISE.J EASTERN CANADA AND NEWFOUNDLAND. 239 

SECTION V. NOVA SCOTIA AND CAPE BRETON.

LITERATURE.

JACKSON and ALGrER,45 in 1832, in remarks on the mineralogy and 

geology of Nova Scotia, find the granites to protrude through the clayslates. They are, however, regarded as older than the slates, the latter 

having been deposited on them in a horizontal position. This granite 

is the only Primitive rock of Nova Scotia. The line of junction between 

the slate and granite was not observed. The slates are cut by numerous dikes believed to be of igneous origin in age posterior to the slate.

BROWN,46 in 1843, places the whole northern part of eape Breton in 

the Primary rocks. Cape North is composed of mica-slate, gneiss, and 

granitic rocks apparently interstratified, with an east and west strike, 

and upturned nearly on edge. Igneous jocks occupy a large part of 

the island. These protrude through the limestones and graywackes, 

which are associated with the coal measures.

DAWSON (SiR WiLLiAM),47 in 1850, divides the metamorphic rocks of 

eastern Nova Scotia into two groups; one along the Atlantic coast and 

vicinity, and another belt to the west, parallel to the first. The coast 

group consists of quartzites, mica-slates, and clay-slates, which are cut by 

granites, and it is therefore called the granitic group of metamorphics. 

The second group, the slates and quartzites, include micaceous and 

talcose schists, while the intrusive rocks are syenites and the group is 

therefore called the syenitic group. The syeuitic group rests unconformably below the carboniferous rocks, the latter containing fragments 

from the former. These are seen at numerous points. Both of these 

groups of rocks are regarded as belonging to the fossiliferous series, 

the syenitic group being Silurian. The granitic group is probably 

older than the syenitic, and therefore also Silurian or pre-Silurian, 

but the actual superposition of the beds of the two groups were not 

observed.

DAWSON (SiR WiLLiAM),48 in 1855 and 1868, places in the Upper Silurian large areas in the northern and eastern parts of cape Breton as well 

as other smaller areas; large areas in northern Nova Scotia, and in 

southern Nova Scotia northwest of the gold-bearing series. The rocks 

have been subjected to great disturbances and are much complicated 

in structure. They include many varieties, syenite, porphyry, greenstone-slates, quartzites, conglomerates, and sandstones. Large areas of 

granitic rocks are also found associated with the metamorphic series 

referred to the Upper Silurian.

The Lower Silurian covers a very large area along the Atlantic coast 

of Nova Scotia known as the gold-bearing series. This area has afforded 

110 fossils but appears to be a continuation of the older slate series of 

Jukes of Newfoundland whijch contain Paradoxides. Among the metamorphic rocks of this region are gneiss, mica-slate, quartz-rock or 

quartzite, and clay-slate. The gneiss is unquestionably the product of
240 PRE-CAMBRIAN BOCKS OF NORTH AMERICA. [BULL. 86.

metamorphisni due to th e bakin g of sedimentary rocks by heat and water, 

while quartzite consists of grains of flinty sand fused together. The 

preponderant rocks are thick bands of slate and quartzite having a 

general northeast and southwest strike and highly inclined. Whether 

the mica schists and gneiss of cape Canso, and Queen's and Shelburne counties, and the chloritic beds of Yarmouth are to be regarded 

as more metamorphosed members of the Lower Silurian slates or are 

still older deposits remains uncertain. Granite is found in several 

places in the region in large masses projecting through the slates and 

quartzites, and adjacent to the granite these rocks are replaced by 

gneiss and mica-slate or other more highly metamorphosed rocks. The 

metamorphisni of the rocks must have occurred prior to the Carboniferous period, and there is no doubt that the granite rocks have been the 

agent in effecting it, if they are not themselves portions of the stratified beds completely molten and forced up by pressure against and into 

the fissures of the neighboring unmelted rocks. Whatever view is 

taken as to the age of the granitic rocks, it is certain that they are 

strictly Hypogene, that is, they belong to deep-seated foci of subterranean heat and are not superficial products of volcanic action, but 

were probably at one time deeply buried.

CAMPBELL,49 in 1863, divides the gold-bearing slates into a lower or 

quartzite group and an upper or clay slate group.

HiND,50 in 1869, finds in the Waveiiy beds of the gold-bearing rocks 

obscure fossils, which are regarded as evidence that these rocks probably lie near the base of the Lower Silurian, perhaps being the equivalent of the Potsdam or lower part of the Calciferous.

HiND,51 in 1870, describes the series of gneissic and granitic rocks 

which are said to extend as an interrupted axis from the Gut of Can so 

to the Tusket islands. These have heretofore been regarded as eruptives, because dikes of granite are frequently found in the quartzites 

which are supposed to be Silurian, and also fragments of quartzites and 

slates are imbedded in the granites near the contacts. It is, however, 

concluded that the granite is a sedimentary deposit resting unconformably below the slates and quartzites. The chief proof of the aqueous 

origin of the granitic rocks is the abundance of water-worn pebbles and 

bowlders, and this not only near the junction of the quartzites but 

remote from, these rocks. These pebbles are symmetrically arranged, 

showing the dip of the gneiss. They are often smooth and rounded, 

but masses of schists are also contained which do not present rounded 

edges. The granites or gneisses are seen to break through the goldbearing series in many places, but they are regarded as brought up by 

faulting; but in certain places on the line of the Halifax and Windsor 

railroad the gneisses were in a plastic state when the uplift took place, 

for veins are found squeezed into the cracks and interspaces of the 

thinly bedded gold-bearing rocks.

The sequence of formations is Upper Silurian, Lower Silurian, Cam-
VASTHWB.] EASTERN CANADA AND NEWFOUNDLAND. 241

\ brian or Hurouian, and Lanrentiau. The Upper Silurian is a series of 

argillites estimated at 9,000 feet thick. The Lower Silurian consists of 

micaceous, schistose and corrugated black slates, and are estimated to 

have a thickness of from 12,000 to 15,000 feet. The gold-bearing Silurian 

rocks are seen to rest uncouforniably on a gneissoid series between Stillwater and Uniacke station on the Halifax and Windsor railway, and 

near the village of Sherbrooke, in Guysboro county. This series of 

Huronian rocks is composed of beds of gneiss, interstratified with micaceous schists, schist-conglomerate, beds of true quartzite, and grits. 

The gneiss is sometimes porphyritic, and the upper beds are almost 

always conglomeratic, holding pebbles and masses of schists, grits, and

i conglomerates, which are found in this series. This older series rests 

unconforniably upon the Laurentian. The- contacts are visible on the 

Windsor and Halifax railway, near New Still water and Mount Uniacke 

stations. The gold-bearing Silurian strata are also found to repose unconformably upon th,e Laurentian. This contact is also observed near 

Mount Uniacke station.

SiLLBiAN,52 (year unknown), finds that the gold-bearing rocks of Nova 

Scotia extend along the Atlantic coast for 250 miles, from, cape Sable, 

to cape Canso. These rocks are hard, slaty ones, which are sometimes 

micaceous schists, and occasionally granitic. When stratified they are 

always found standing at a high angle, sometimes almost vertical, and 

in the main with an east and west course. The zone of metamorphic 

rocks varies in width from (I to 8 miles at its eastern extremity to 40 

or 50 at its widest part, the area covered being about 6,000 square 

miles. While no fossil evidence has been found in any of these slates, 

opinion seems to favor the belief that they belong to the Silurian age, 

but as yet no place has been found where the rocks next higher in the 

geological column, may be seen resting upon them. The most noticeable rock of the gold region is a dark gray massive rock, resembling 

a trap, but which is really a granular quartzite. It has three well 

denned planes of cleavage by which it breaks into very irregularly 

shaped masses. This rock is of enormous thickness, and is undoubtedly the fundamental or basement rock of the region.

LOGA.N and HARTLEY,58 in 1870, describe felsites, quartzites, conglomerates, and slates, adjacent to the Pietou coal fields, which are 

pre-Carboniferous, and are placed as probably of Devonian age.

SELWYN,54 in 1872, in studying the gold-bearing slates, agrees with 

Dawson that they belong to the Primordial-Silurian, epoch. As evidence of this is given the discovery in the slates of Oven's bluffs of 

numerous specimens of the genus Eopliyton.

The granite impresses this author .as of strictly indigenous character, 

and neither a granitoid g-neissic series of Laurentian age nor an intrusive mass. The line of contact with, the Silurian and Devonian leaves 

no doubt of its posterior origin, but whether intrusive or metamorphic in situ is perhaps uncertain. 

Bull. 86 16
242 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 88.

Boss,55 in 1876, finds that a massive syenite and associated crystalline rocks have a quite widespread distribution in cape Breton. At 

some points the Carboniferous rocks are brought in contact with the 

syenite, but generally there are interposed metamorphic calcites, argillites, and quartzites associated with dolomites, and other magnesian 

rocks, which are in a vertical or highly inclined position, and evidently 

belong to a pre-Oarboniferous altered sedimentary series. The junction 

of the pre-Oarboniferous limestones with the syenite is approximately 

parallel to the mountain range, but is locally irregular, and in some instances the limestones seem to fill depressions in the syenite. The 

Lower Carboniferous rocks in places rest directly upon the syenite, filling the hollows in it, and have basal conglomerates, the debris of which 

is derived from the overlying syenite, limestone, and quartzite.

FLETCHER,56 in 1877, finds in cape Breton, below the Silurian rocks, 

first, a set of syenitic, gneissoid, and felsitic rocks 5 and second, the 

George river limestone series, consisting of crystalline limestones and 

dolomites, interstratified with felsite, syenite, diorite, mica-schist, quartzite, and quartzose conglomerate, both of which are referred to the 

Laurentian, although the latter may be Huronian. The Lower Silurian shales lie nearly horizontally upon the syenites a,nd felsites without 

any appearance of alteration and without being intruded by the felsites 

or syenites. The crystalline limestone series is in close affinity with 

the feldspathic group of rocks, but is distinct, as is shown by the occurrence of pebbles of syenite and felsite in the quartzose conglomerate 

of Murphy brook.

FLETCHER,57 in 1878, continues his study of the pre-Cambrian of 

cape Breton and northern Nova Scotia. The George river limestone is 

bounded upon both sides by coarse syenitic and granitic rocks and is 

in apparent conformity with them.

DAWSON58 (Sir William), in 1878, places the rocks of the Bloisdale 

hills in cape Breton as older than the Lower Silurian, and it is not impossible that rocks of the same age may occur in the vicinity of the 

Cambrian beds at Mire". Also the chloritic rocks of Yarmouth may conjecturally be placed with the Huronian. With the exception of the 

rocks of St. Anns mountain, of the island of St. Paul, and some parts 

of northern cape Breton, no rocks are found which are regarded as 

lithologically equivalent to the Laurentian of Canada.

FLETCHER,59 in 1879, describes the pre-Primordial rocks as occupying 

two large areas, one constituting the Mira hills, while the other is a belt 

of variable width along the shore of the Atlantic. There are two 

basins of metamorphic rocks running parallel to the felsite series, one 

of which abounds in Primordial fossils and the second probably of 

Devonian age. The latter contains masses of granitoid and trappean 

rocks.

FLETCHER,60 in 1881, in continuing his studies in northern Nova 

Scotia, again divides the pre-Cambrian rocks into two groups. In the
VANHISE.] EASTERN CANADA AND NEWFOUNDLAND. 243

first, or felsitic group quartzites are also found intimately intermingled. 

The George river limestone series is considered as an unconformable 

overlying group of pre-Oambrian age. The limestones in every case 

cap the felsites, with which, however, they often seein to blend near 

the contacts as if by a common metamorphism. As evidence of this 

unconformity are cited the occurrences of limestone in a higher position 

than the syenites and felsites; the irregular line of contact by which the 

syenite passes under the limestone; and the absence of veins and dikes of 

syenite in the limestone. The rocks are sometimes intricately mingled, 

as at Dallas brook, where layered felsite, limestone, and slate are met 

with, while on the top of the hill limestone occurs, and farther back 

syenite, displaying a coarse admixture of finely foliated gneiss. In some 

localities the syenite begins abruptly as if cutting vein-like across the 

strike of the gneiss; in others the change from syenite to gneiss is 

gradual. The gneiss is associated with large masses of white quartzite. 

Metamorphic rocks are described which are referred to the Devonian, 

but the evidence is so slight that it is concluded that all of these strata 

may belong to an older period. Between them and ,the pre-Cambrian 

series there is a marked unconformity, and also one of less importance 

between them and the Carboniferous.

FLETOHER,61 in 1885, finds that in northern cape Breton the syenitic, 

gneissoid, and other feldspathic rocks of the Lower pre-Oanibrian group 

are intimately mingled* on the Margaree river with foliated rocks. At 

Coinneach brook, where the syenite comes in contact with the contorted 

mica-schist, the latter is seen to underlie the syenite. Higher up the 

syenite again appears and contains a layer 5 feet thick of mica-schist 

which is, as it were, intruded among the syenites. Bed granite overlies unconformably the strata of the George river limestone group at 

Fionnar brook.

GiLPiN,62 in 1886, describes the pre-Cambrian rocks of cape Breton 

as including a felsite series and a crystalline limestone series, both of 

which are referred to the Laurentian, and the latter nnconformably 

overlying the former. With the felsites and interstratified porphyries 

are also syenitic and gneissic rocks; while the crystalline George river 

limestone also contains iaterstratified with the limestones, syenites, 

diorites, mica-schists, quartzites, and quartzose conglomerates. The 

limestone area is limited in extent as compared with the felsite group.

FLETCHER,63 in 1887, further describes the pre Cambrian rocks of a 

part of northern Nova Scotia. The crystalline rocks here found resemble none known as Cambrian in other parts of Nova Scotia, and are 

strikingly like those beneath the Upper Cambrian in cape Breton. 

Although they are certainly known to rest unconformably below the 

Cainbro-Silurian strata, a part of all of these rocks may be Cambrian 

or even Cambro-Silurian. Similar gneisses and schists in southern New 

Brunswick have been included by Bailey in his Cambro-Silurian series. 

Volcanic rocks, both basic and acid and varying in age from pre-Cambrian to Devonian, or even Carboniferous, are abundantly found.
244 rRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL,86.

FARIBAULT, 64 in 1887, reports on the gold-bearing area of southern 

Nova Scotia. These rocks occupy 6,000 or 7,000 square miles. They 

are divided into a granitic division and a lower Cambrian division. 

The lower Cambrian rocks include quartzites, clay-slates, and conglomerates, and are estimated to have a thickness of 15,000 feet. 

These rocks, always greatly altered, are much more so when cut by 

masses of granite, and over considerable districts have been rendered 

thoroughly crystalline, the quartzites passing into fine gneissic rocks, 

and the mica-slates into mica-schists. Following Campbell, they are 

divided into a lower or quartzite group, 11,000 feet thick, and an upper 

or graphitic and ferruginous slate group, about 4,000 feet thick. The 

first of these, while in the main quartzite, is interstratified with 

numerous bands of slates and one or two of conglomerate. The Cambrian rocks are greatly disturbed from, their original horizontally, 

being folded into a series of sharp parallel undulations. In the 

more altered portions the planes of bedding are not easily distinguished from those of slaty cleavage, the latter often being more distinct. The rocks are referred to the Cambrian upon the evidence of a 

single fossil, Eophyton. The group is analogous in some respects to 

Lawson's lake of the Woods series. The granites are found to cut the 

Cambrian rocks at many places, and at times are associated with 

gneisses. At the edge of large masses the granite frequently passes 

into a foliated schistose rock, losing its crystalline texture, and itself 

passing insensibly into the altered sedimentary rocks.

DAWSON (SiR WiLLiAM)65 , in 1888, places the isolated rocks of St. 

Anus mountain in the lower Laurentian, and regards it as probable 

that rocks of this kind exist in the northern extremity of the island. 

In Nova Scotia proper no true Laurentian is recognized, the rocks here 

referred by other observers being intrusive granite masses of much 

later date associated with altered rocks.

SUMMAKY OF KKSULTS.

In Nova Scotia and Cape Breton, as in southern Xew Brunswick, is 

a great variety of eruptive and intrusive rocks, both basic and acid, and 

of varying age. It is also plain that there is to be here included considerable masses of rocks which were in early days referred to the Laurentian. The intrusive character of the granites was appreciated by 

Jackson as early as 1832. Since that time the only observer who has 

not. agreed with this conclusion is Hind, who strongly maintains that 

they are metamorphosed sediments. His facts, however, clearly distinguishable from his theory, point to an eruptive origin of the granite. 

The chief fact cited in favor of their being water-deposited rocks is the 

presence of roundish fragments of slates, quartzites, and schists remote 

from the contacts with these rocks. All the other facts given by him 

i. e., the irregular fashion in which the granite veins intrude the schists, 

the abundance of large angular fragments of these schists and slates
vAxnisE.] EASTERN CANADA AND NEWFOUNDLAND. 2<15'

adjacent to the sedimentary rocks -lire better explained by regarding 

the granite as intrusive. The natural explanation of the rounded bowlders remote from the contacts is that they represent partially absorbed 

pieces of these rocks. The evidence given by Dawson as to the structural relations of the granite and the manner in which the granite fades 

off into the slates, mentioned by Faribault, is wholly conclusive as to 

the intrusive origin of a portion of the granites. The relations thus 

described by Faribault are precisely like those which obtain between 

the granites and intruded metamorphosed schists in the Black hills 

and about Rainy lake and lake of the Woods.

While it is thus certain that large areas of granite and felsite are intrusives of later age than the rocks which are certainly of clastic origin, it does not follow that a portion of the felsites, porphyritic gneissesand granites are not of earlier age than any of the plainly clastic rocks.

It is of interest to note that while Dawson insists that all of the 

granites of Nova Scotia proper are of truly Hypogene origin of later 

age than the sedimentaries, that he suggests that it is not improbable 

that they have themselves been produced by the actual fusing of these 

sedimentaries. This hypothesis is the same as that proposed by Lawson many years later to explain analogous phenomena between the 

granites and gneisses and the associated schists and elastics of Rainy 

lake and the lake of the Woods.

In considering the positions and successions of the plainly clastic 

rocks of cape Breton and Nova Scotia, we have two geological provinces : the first including northern Nova Scotia and cape Breton, which 

is analogous to southern New Brunswick; and; second, the main part 

of Nova Scotia, south of the line running from Minas basin to Chedabucto bay.

In the second of these regions, aside from the granites, the only area 

that is of interest in connection with our study is the gold-bearing Atlantic coast series. Dawson in 1850 places this as Lower Silurian 

or pre-Silurian. Later, in his Acadian G-eology, it is classified as 

Lower Silurian, although it is stated that no fossils are found in them. 

Later it was placed by Faribault as Lower Cambrian. The only 

evidence cited by him for placing it in the fossiliferous series at all 

is the presence of the obscure fossil Eophyton, discovered by Selwyn. 

Dawson found no fossil evidence for his reference of this series to the 

Silurian; audit is remarked by Sillhnau that immediately overlying 

rocks containing fossils have never been found. Although Hind in 

1870 says that the fossiliferous Upper Silurian conformably overlies the 

gold-bearing series, this statement has been found nowhere else and 

subsequent observers have not repeated it, so that it maybe considered 

very doubtful.

It is then clear that the position of the gold-bearing slates in the 

Lower Silurian or Lower Cambrian is purely provisional. They can 

only be considered as certainly belonging here under the premise that
246 PBE-CAMBRIAN ROCKS OF NORTH AMERICA. i»uu,86.

we are to place in the Cambrian, all rocks which contain well recognized 

fossils or show the evidence of life. Similar reasoning would place in the 

Cambrian a large part of the rocks which have heretofore been referred 

to the Animikie and the Huronian in the lake Superior region. This 

question is more fully discussed in another place. We know positively 

only that the gold-bearing series is pre-Carboniferous, as the Carboniferous rocks are the oldest found in contact with the former. Between 

these two is a great unconformity. How much time this break represents we have at present no means of judging.

Dawson is uncertain whether the more crystalline mica-schists and 

gneisses, which have a somewhat widespread occurrence in southern 

Nova Scotia, are to be regarded as older than the gold-bearing slates. 

Hind, in 1870, maintained that a set of older schists and gneisses lie 

unconformably below the slates on the Windsor and Halifax railway. 

Not only this, but that this set of schists and gneisses is unconformably 

above another series which he referred to the Laurentian. As no subsequent observer has mentioned the first of these unconformities, and 

as it occurs at so readily accessible a place, it may well be considered 

doubtful whether the facts were rightly interpreted. As suggested by 

Faribault, it does not appear at all improbable that the gneisses associated with the gold-bearing slates are due to dynamic and contact 

metamorphism of the intruding granite. The coarsely crystalline rocks 

which Hind referred to the Laurentian are certainly the series which 

Dawson and other observers regard as later granitic eruptions, and the 

unconformity mentioned is perhaps an eruptive unconformity.

In northern Nova Scotia and in cape Breton, among the rocks referred 

to the pre-Cambrian there is a great variety of rocks both eruptive and 

sedimentary. The sedimentaries are frequently much more metamorphosed than are the gold-bearing series of Nova Scotia. With commendable caution Eobb, in 1876, only says of this older series that it 

is pre-Carboniferous. Later, Fletcher, on lithological grounds, correlated it with the Laurentian of Canada, and, like the original area of 

the Laurentian, the Ottawa rocks, he divided it into an Upper and 

Lower Laurentian, the lower consisting of various massive and laminated rocks all presumably of igneous origin whatever their age, and the 

upper series, including all limestones, sandstones, slates, conglomerates that is, all which are certainly clastic in character. Associated 

with this upper series are eruptives of. the same character as those found 

in the Lower Laurentiau.

These two parts of the Laurentian were first described as in apparent conformity, but in 1881 Fletcher describes them as probably unconformable. The detailed evidence for this conclusion it has not been 

possible fully to give in the foregoing summary, but a close scrutiny of 

the evidence seems to point more strongly toward the later intrusive 

character of the so-called Lower Laurentian. The lines of contact between the Lower and Upper Laurentian are very irregular, and in gen-
vANiuste.1 EASTERN CANADA AND NEWFOUNDLAND. 217

eral are Ibund at a lower level than the Upper Laurentian, but both of 

these would be true if the Lower Laurentian were intrusive. The manner in which the syenite passed into the foliated gneiss, a.nd the foliated 

gneiss into the ordinary schist associated with the elastics at Dallas 

brook, appear to indicate the intrusive character of the supposed Lower 

Laurentian at this place. It is very strange that basal conglomerates 

have not been found in the upper series which bear fragments of the 

underlying one, if the former is really newer and nnconformable. The 

interstratifted syenites, diorites, etc., placed with the limestone series are, 

without question, igneous rocks. So that there can be no doubt that 

many rocks of the same character as the so-called Lower Laurentia.n 

are igneous and later than the clastic series, which makes it probable 

that much of this so-called lower series is of the same age. While all 

of this is true, as before remarked, it is not certain that a portion of 

the so-called Lower Laurentian may not be of greater age than the 

clastic Upper Laurentian rocks.

The gold-bearing series referred to the Cambrian in southern Nova 

Scotia are nowhere found in contact with the pre-Cambrian of northern 

Nova Scotia and cape Breton. As has been said, we only know that 

the gold-bearing slates are un conformably below the Carboniferous. The 

supposed pre-Cainbrian rocks of northern Nova Scotia and cape Breton 

are known only to be unconformably below the Cambro-Silurian. In 

this district not only are the igneous rocks apparently more abundant 

than in southern Nova Scotia, but the folding is of a more intricate 

character. So far as one can see, there is no evidence that the clastic 

series to the north is not of the same age as the Atlantic coast goldbearing series, being, perhaps, more metamorphosed because of the folding and presence of eruptive rocks.

Summing up, it can only be said that all of the clastic rocks of Nova 

Scotia and cape Breton, so far as we have any positive evidence, may 

belong as high as Cambrian, as stated by JFletcher in his later work, or 

may be of pre-Cambrian age and the equivalent of certain one or more 

of the pre-Cambria.n series.

SECTION VI. NEWFOUNDLAND.

LITEKA.TUKE.

JUKES,66 in 1843, divides the lower formations of Newfoundland in. 

descending order into an upper slate formation, a lower slate formation, and a gneiss and mica-slate formation. The igneous rocks consist of various kinds of trap, greenstone, serpentine, hypersthene, porphyry, syenite, and granite. The upper slate formation is believed to 

be lower than the coal formation, although nowhere found in contact 

with it. The thickness of the upper slate must be many hundreds of 

feet. In one instance beds of upper slate rest unconformably upon 

those of the lower slate formation. The mica slate and gneiss or quartz
248 PRE-CAMURIAN ROOKS OF NORTH AMERICA. rnrr.T..8fi.

rock, chlorite slate, and primary limestone occur together. Nearly the 

whole of the province of Avalon is composed of the lower slate formation. On Conception bay at several places beds of variegated slate 

overlap and cover the edges of the lower slate in a perfectly unconformable position.

On NewelPs island the junction of the gneiss and mica-slate with the 

granite is found. The mica-slate in approaching the granite becomes 

more crystalline and gneiss-like in certain layers. On continuing to 

approach the granite there appear thin beds of granite, which are not 

veins from the granite but an integral part of the beds. The granite 

becomes more abundant in getting toward the main mass of this rock, 

the alternations increasing in frequency, until after passing over the 

edges of many beds, the red and flesh-colored, perfectly crystalline 

granite, with no appearance of any lamination or bedding whatever, is 

imperceptibly reached. In the granite itself, for some distance from 

the junction, nodular masses of black rock, consisting of minute scales 

of mica were observed. In other places the mica-slate and gneisses 

alternate with each other and are cut by distinct granite veins.

The cleavage of the slate rock's is frequently parallel to the planes of 

stratification, but often cuts them at all angles. The strike of the 

cleavage is in a great majority of instances parallel to the strike of the 

beds, but not invariably so. The cleavage is much more constant as 

regards its strike and dip than is the strike and the dip of the beds. 

The dip of the cleavage is never at a less angle than 45°, while in the majority of instances it is nearly perpendicular. Its strike was not in any 

instance found to vary more than 10° or 15° from a NNE. and SSW. 

bearing. Certain of the granites are newer than the mica-slate an<l 

gneiss. Also some of the porphyritic granite is more modern than some 

of the shales. In other cases the red igneous rock, generally the syenite, is in all probability one of the oldest rocks in the country, as no 

veins were observed to proceed from it into the adjoining formations, 

and a rounded pebble of a precisely similar rock is found in a bed belonging to the.older sla.te formation in Great Placcntia.

MURRAY,157 in 1865, describes the geology of the northeastern part of 

Newfoundland. Here is found a Laurentian group, which consists 

mostly of gneisses, but contains in places layers of mica-slate and whitish 

quartzite. These rocks are placed in the Laurentian because they have 

a lithological resemblance to the Laurentian of Canada, and because 

they are covered unconformably by the Lower Silurian strata. No crystalline limestones such as are associated with the Laurentian of Canada 

are found interstratified with the gneisses. The rocks of the overlying 

Potsdam, and Quebec group are fossiliferous.

MURRAY,08 in 1868, gives an account of a part of the coast of Notre 

Dame bay. A section of rocks in this locality consisting of slates, 

quartzites, dolomites, with various eruptives, is referred in part to the 

Quebec group. Among the intrusives are syenite and diorite. At
U.S GEOLOGICAL SURVEY. BULLETIN 86 PL VI.

UNCLASSIFIED PRE-CAMB. ALGONKIAN ALGONKIAN? POST -ALGONKIAN ERUPTIVES

GEOLOGICAL MAP OF NEWFOUNDLAND

SHOWING PRE-CAMBRIAN Al JD CRYSTALLINE ROCKS

Compiled from m'ap byAlex Mun-ay 

Scale 'J.SOO.ODO.
EASTERN CANADA AND NEWFOUNDLAND. 240

Laseie .harbor the rocks are ina/inly gneiss, resting un com form ably upon 

which is a great mass of nnstratifted quartzite.

MURRAY, in 1808, treats of the peninsula of Avalou. ' Here is found 

a gneiss which is referred to the Laureutiau. Intermediate between 

this gneiss and the Lower Silurian strata is a great thickness of slates 

and quartzites, which are referred to the Huronian. Resting unconIbrmably upon these rocks are others containing Potsdam fossils.

In the Laiirentian are placed the gneisses of Conception bay, the 

masses of granite, syenite, and porphyries of St. Johns peninsula described by Jukes, and the granites of Placeutia bay and Sound island. 

These rocks are like those referred to the Laiirentian in the great northern peninsula. The intermediate system consists of diorites, quartzites, 

slate conglomerates, slate and sandstone, the whole series in Conception bay being over 11,000 feet thick. This series resembles litholo^ically the Huronian system of Canada in a high degree, although it may 

be admitted that lithological relations are of secondary importance in 

correlating rocks which are remote from each, other. In one member of 

the group is a fossil, designated as Asnidella, of alow order of existence, 

which leads to the conclusion that the system isproba,bly Cambrian. This 

series of rocks occupies by far the greater part of the peninsula of Avalon. The lower rot !cs in all cases pitch at a very high angle to the horizon, the prevailing inclination being to the eastward, while the upper 

formation, except where disturbed by eruptives, is either in a perfectly 

horizontal attitude or only slightly inclined. The lower series is also 

marked for its general absence of lime, while the upper formation is 

nearly all more or less calcareous. Further, the Potsdam rocks were 

found to overlie uncomformably the lower slates at Manuels brook and 

at Brigus South Head. The Nova Scotia gold-bearing rocks are lithologically like the system referred to the Huronian in Newfoundland, 

although they have been referred to the Lower Silurian.

MURRAY,70 in 1.870, finds the rocks of Bonavistabay to consist largely 

of slates, slate-conglomerates, quartzites, and diorites, intersected by 

intrusive granite or syenite, trap, and quartz veins. This series has 

such a close lithological resembhin.ee to the intermediate system of 

Avalou that there is no doubt of their identity. These rocks also occur 

between the gneiss and the Paleozoic formations of Trinity bay.

HowLEY,71 in 1870, describes sundry parts of the coast. The rocks 

of cape Hay and the extreme head of Conception bay are of a gueissoid 

character. Granite, syenite and trap are interbanded with, quartzite. 

Upon Great Miquelon island is found gneiss, supposed to be of Laiirentian age. Greenstones and granite break at various pi aces through the 

stratified rocks.

MURRAY,72 in 1873, gives a further account of the Avalon peninsula. 

The line of contact between the Huronian and more recent rocks in 

Trinity bay is obscure and difficult to detect, and here Aspidella is very 

useful in deciding to which series the rocks belong. The rock's on the
* 250 PEE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 8ft.

west coast of Trinity bay are correlated with the Huronian on Hthological evidence. The rocks here are in some respects different from those 

on St. Johns peninsula, but this difference seenis to be due to the intense volcanic activity which has affected the western part of Aval on. 

Dikes of various kind intersect the formation, and the strata are in 

places volcanic conglomerates, volcanic ashes, etc. The rocks of Brigne, 

described in the report for 1868, are found to contain several beds which 

are crowded with Aspidella.

MURRAY," in 1873, finds gneissic rocks at several localities in St. 

Georges bay. Associated with these are labradorite and other anorthosite rocks which belong to the upper Laurentian system. Also, on the 

Great Codroy river is found white crystalline limestone with graphite, 

which is regarded as a further indication of the presence of this division of the Laurentian.

MURRAY,74 in 1875, finds on Gander lake micaceous slate, fine grained 

granite, and gneiss, which a,re correlated with the Laurentian gneiss of 

Boriavista bay.

HOWLEY,75 in 1877, further examines Gander lake and river and finds 

chlorite-slates, diorites, and mica-slates which contain no organic remains, 

and which on account of their lithological character and the serpentine 

they contain are provisionally placed with the Quebec group. Upon 

the upper Gambo pond and Klverhead brook are found sandstones and 

quartzites which at some places pass almost imperceptibly into gneiss, 

which rocks, with the associated micaceous slates, are provisionally 

placed with the Huronian.

HOWLEY, in 1882, further describes the intermediate system of Huronian rocks. These metamorphic rocks occupy the greater part of the 

peninsula of Aval on. They rest upon a nucleus of Laurentian gneiss 

and are succeeded by fossiliferous beds of the Primordial age which 

skirt the shores of the bays* and are found to refct unconformably on 

the basset edges of the upturned and altered Huronian, and occasionally in contact with the still older Laurentian. The intermediate rocks 

are found to be gently folded so that the same strata are repeated several times. Associated with these Huronian rocks are trappean beds 

and volcanic ash. Contained in them are found two fossils, Aspidella, 

terranovica and Arenicolites spirales. This latter fossil is said to occur 

in the Primordial rocks of Sweden. These fossils give important 

assistance in the ready recognition of the Huroniau. The gneissic 

rocks which have been described as being members of the Laurentian 

system protrude through the Huronian strata by which they are surrounded. Cutting the Huronian rocks is found a series of granitoid 

and other plutouic rocks which obliquely intersect the eastern part of 

the peninsula, including the Laurentian gneiss. A second great igneous intrusion cuts all of the rocks of the western part of the peninsula, 

including the Potsdam sandstone. The intrusions of the eastern peninsula are taken to be of older date than the trap of the western penin-
AAN BISK.] EASTERN CANADA AND NEWFOUNDLAND. 251

sula, although probably later than Huronian, as the former is never 

found to cut the Potsdam sandstone.

WALCOTT,77 in 1889, corroborates the unconformity between the 

series referred by Murray to the Huronian and the overlying' series 

called Potsdam. This latter is found to contain the Olenellus fauna 

below the Paradoxides and is placed as lower Cambrian.

SUMMARY OF KKSULT8.

The reports of Jakes and Murray are far more complete as to the 

geology of the peninsula of Avalon and the district immediately to the 

west than they are of the great northern peninsula. The map of this 

latter area is greatly generalized.

The unconformity described between the Upper and Lower slate of 

Jukes is evidently the same as that found by Murray between his Potsdam and Huronian. The Potsdam was later determined by Walcott to 

be basal Cambrian.

It is perfectly clear that in Newfoundland, and particularly in Avalon 

and southeastern Newfoundland proper, is a great series of fragmental rocks unconformably below a series bearing the Olenellus fauna. 

Tliis series is of great thickness, probably more than 10,000 feet. In 

certain layers it carries obscure fossils which, according to Walcott, are 

of an earlier form than those of the Cambrian. It then follows that in 

this region we have a pre-Cambrian series of rocks bearing a small fauna 

of a rudimentary type. This result is very important as giving a start 

toward a fauna which, whatever the series in which it is found shall be 

called, is greatly older than that now recognized as basal Cambrian. 

Whether the series shall be called Huronian, as is done by Murray, depends upon the definition of that term. If all pre-Cambrian clastic 

series are to be placed in the Huronian, this series can be said to belongto that age, but if only those rocks are to be here placed which are the 

equivalent of those referred to that term on the north shore of lake 

Huron, we have as yet no means of determining whether the Newfoundland series is Huronian or not.

The relations of the series referred to the Huronian with the granites, 

gneisses and schists which are placed with theLaurentianarefar less satisfactorily known. Nowhere is anything said as to any structural breaks 

between these two series, and evidently the lines between the so-called 

Laurentian and Huronian are based upon a very general study. Jukes, 

Murray and Ho wley agree that in Avalon and in other parts of Newfoundland are large areas of eruptive rocks, includm g both basic and acid kinds, 

which cut the various sedimentaries. Murray does not find that the Cambrian of Avalon is cut by granites and porphyries, but, according to 

Jukes, in other parts of Newfoundland this is the case. However, both 

basic and acid eruptives, including granites, syenites and porphyries, 

are found to cut in the most intricate manner the pre-Cambrian sedimeutaries, and as a result of this, this series is found to be more than usually
252 PEE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL, 80.

metamorphosed in the urea between Trinity and Bonavista bays. The 

peculiar manner in which the granitic rocks vary into the slates by 

gradual inteiiaminations, combined with the occurrence of fragments 

of the schists within the granite, so well described by Jukes and corroborated by Howley, indicate that a large part of the rocks referred to 

the Laurentian are certainly intrusive, and that the more crystalline 

character of the clastic formations adjacent to them are due to metamorphism. It is then by no means clear that within Avalon are any 

rocks of sedimentary origin older than the series referred to the Hnronian, although the fact mentioned by Jukes of a single bowlder of syenite in the older slate series indicates the probability of a pre-Huronian 

syenitic or gneissic series. At present we have, however, no means of 

judging what part of the rocks referred to the Lanrentian are later intrust ves and what part, if any, are older than the pre-Cambrian clastic 

series.

As to the rocks referred to the Upper Laurentian because of the presence of anorthosite rocks and limestones, the question arises as to 

whether the crystalline limestones associated with the gneisses are not 

of later age than supposed, being perhaps more metamorphosed. The 

associated anorthosite that is, a probably eruptive rock may be an 

explanation of this metamorphism. If the presence in Newfoundland 

of a Lower Laurentian is doubtful, it is much more doubtful whether 

here an upper series of fragmental rocks has been shown to exist which 

are older than the pre-Cainbrian series referred to the Huronian.

The observations made by Jukes as to the relations of slaty cleavage 

and bedding are of the greatest interest and importance. The strike 

of the cleavage is in a great majority of instances parallel to the strike 

of the beds, but not invariably so. The cleavage is much more constant as regards its strike and dip than is the strike and the dip of the 

beds. The dip of cleavage is never at a less angle than 45°, while in 

the majority of instances it is nearly perpendicular.

NOTES.

1 The Metamorpliic Rocks of the Notre Dcime Mountains, Alexander Murray. Rept. 

of Prog. Geol. Survey of Canada for 1845-;46, pp. 111-114.

~ Report of Progress of the Geological Survey of Canada from its Commencement 

to 1863, AV. E. Logan, pp. 983. With an atlas.

' * Report of Observations on the Stratigraphy of the Quebec Group and the Older 

Crystalline Rocks of Canada, A. R. C. Selwyn. Rept. of Prog. Geol. Survey of Canada for 1877-'78, pp. 1-15 A.

4 Notes ou. the Geology of the Southeastern Portion of the Province of Quebec, A. 

R. C. Selwyn. Rept. of Prog. Geol. and Nat. Hist. Survey of Canada for 1880-'81-'82, 

pp. 1-7 A.

6 The Quebec Group in Geology, with an Introductory Address, A. R. C. Selwyn. 

Proc. and Traus. of the Royal Soc. of Canada for 1882 and 1883, vol. i, sec. 4,1882, pp. 

1-13.

"Report on the Geology of a Portion of the Eastern Townships of Quebec, relating more especially to the Counties of Comptou, Stanstead, Beauce, Richmond, <iud
EASTERN CANADA AND NEWFOUNDLAND. 253

Wolfo, R. W. Ells. Kept, of Prog. Geol. and Nat. Hist. Survey of Canada for 1886, 

new series, vol. n, pp. 1-70 J. With a colored geological map.

7 Ibid., footnotes, pp. 23 J. 29 J, 36 J.

8 Second Report on the Geology of a Portion of the Province of Quebec, R. W. 

Ells. Annual Rept. of Geol. and Nat. Hist. Survey of Canada for 1887-'88; vol. m, 

new series, part 2, pp. 1-120 K.

9 Account of Explorations in theEastern Townships of Quebec, F. D. Adams. Ibid., 

part 1, pp. 27 A, 28 A, 84 A, 85 A.

10 Personal Communication.

11 Report on Explorations and Surveys in the Interior of Gaspe" Peninsula and 

Prince Edward Island, R. W. Ells. Rept. of Prog. Geol. and Nat. Hist. Survey and 

Museum of Canada for 1882-'83-'84, pp. 1-34 E.

'- Report on Explorations and Surveys in the Interior of Gasp6 Peninsula., A. P. 

Low. Ibid., pp. 1-21 F. With a map.

13 On the Geology of a part of New Brunswick, Charles Robb. Rep. of Prog. Geol. 

Survey of Canada from 1866 to 1869, pp. 172-209. With a sketch map.

14 Supplementary Report on the Geology of Northwestern New Brunswick, Charles 

Robb. Rept. of Prog. Geol. Survey of Canada fur 1870-'71, pp. 241-251.

15 Report on the Geology of Northern New Brunswick, embracing Portions of the Counties of Restigouche, Gloucester, and Northumberland, R. W. Ells. Ropt. of Prog. 

Geol. and Nat. Hist. Survey of Canada for 1879-'80, pp. 1-47 D.

16 Keport on Northern and Eastern New Brunswick and North Side of the Bay of 

Chaleurs, R. W. Ells. Rept. of Prog. Geol. and Nat. Hist. Survey of Canada for 

1880-'81-'82, pp. 1-24 D., with a 5-sheet geological map.

17 Report of Explorations and Surveys in Portions of York andCarleton Counties, 

New Brunswick, L. W. Bailey. Rept. of Prog. Geol. and Nat. Hist. Survey and Museum of Canada for l882-'83-'84, pp. 1-31 G. With geological sheets.

1S Report on Explorations and Surveys in Portions of the Counties of Carleton, 

Victoria, York, and Northumberland, NCAV Brunswick, L. W. Bailey. Ann. Rept. of 

Geol. and Nat. Hist. Survey of Canada for 1885, vol. i, new series, pp. 1-30 G. With a 

map.

'' ' Report on Explorations in Portions of the Counties of Victoria, Northumberland, 

and Restigouche, New Brunswick, L. W. Bailey, and W. Mclnues. Ann. Rept. of 

Geol. and Nat. Hist. Survey of Canada for 1886, vol. ir, new scries, pp. 1-19 N. With a 

map.

20 First Report on the Geological Survey of the Province of New Brunswick, Abraham Gesuer, pp. 87.

21 Second Report on the Geological Survey of the Province of New Brunswick, 

Abraham Gesner, pp. 76.

'"Third Report on. the Geological Survey of the Province of New Brunswick, Abraham Gesner, pp. 88.

23 Fourth Report on the Geological Survey of the Province of New Bruuswick, 

Abraham Gesner, pp. 101.

-4 Report on the Geological Survey of the Province of NOAV Brunswick, with a Topographical Account of the Public Lands, Abraham Gesner, pp. 88.

26 Report on the Agricultural Capabilities of the Province of New Brunswick, J. 

F. W. Johnstou, pp. 262. Accompanied by a soil map,

2fi Observations on the Geology of Southern New Brunswick, L. W. Bailey, Geo. F. 

Matthew, and C. F. Hartt, pp. 158. Accompanied by a geological map.

27 On the Azoic and Palicozoie Rocks of Southern New Brunswick, G. F. Matthew. 

Quart. Jour. Geol. Soc.; London, vol. xxi; 1865, pp. 422-434. See also Can. Nat., 2d 

series vol.m, 1868, pp. 387-391.

28 A Preliminary Report on the Geology of New Brunswick, together with a 

Special Report on the Distribution of the "Quebec Group" in the Province, Henry 

Youle Hiud, pp. 293.
254 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

59 Remarks on the Age and Relations of the Metamorphic Rocks of New Brunswick and Maine, George F. Matthew and L. W. Bailey. Proc. Am. Aesoc. Adv. Sci., 

1869, 18th Meeting, pp. 179-195.

30 Preliminary Report on the Geology of Southern New Brunswick, L. W. Bailey 

and G. F. Matthew. Rept. of Prog. Geol. Survey of Canada for 1870-'71, pp. 13-240.

31 On the Physiography and Geology of the Island of Grand Manan, L. W. Bailey. 

Can. Nat., 2cl series, vol. vi, $p. 43-54, with a map.

32 Summary of Geological Ohservations in New Brunswick, L. W. Bailey and G. 

F. Matthew. Rept. of Prog. Geol. Survey of Canada for 1874^'75, pp. 84-89.

33 Report of Geological Observations in Southern New Brunswick, L. W. Bailey, 

G. F. Matthew, R. W. Ells. Rept. of Prog. Geol. Survey of Canada for 1875-76, pp. 

348-368.

34 Report on the Slate Formations of the Northern Part of Charlotte County, New 

Brunswick, with a Summary of geological observations in the southeastern part of 

the same county, G. F. Matthew. Rept. of Prog. Geol. Survey of Canada for 1876-'77. 

pp. 321-350. Accompanied by a map. 

85 Report on the Lower Carboniferous belt of Albert and Westmoreland Counties, 

New Brunswick, including the Albert shales, L. "W. Bailey and R. W. Ells. Ibid., pp. 

351-395. Accompanied by a map.

3(5 Report on thePre-Silurian rocks of Albert, Eastern Kings, and St. John Counties, 

Southern New Brunswick, R. W. Ells. Rept. of Prog. Geol. Survey of Canada for 

1877-'78, pp. 1-13 D.

37 Report on the Pre-Silurian (Huronian) and Cambrian, or Primordial Silurian 

Rocks of Southern New Brunswick, L. W. Bailey. Ibid., pp. 1-34 DD.

38 Report on the Upper Silurian and Kingston (Huronian) of Southern New Brunswick, G. F. Matthew. Ibid., pp. 1-6 E.

39 Report on the Geology of Southern New Brunswick, embracing the Counties of 

Charlotte, Sunbury, Queen's, King's, St. John, and Albert, L. W. Bailey, G. F. Matthew, and R. W. Ells. Rept. of Prog. Geol. Survey of Canada for 1878'-79, pp. 1-26 

D. With a geological map.

10 On the Progress of Geological Investigation in New BrunsAvick, 1870-1880, L. W. 

Bailey. Proc. Am. Assoc. Adv. Sci., 1880, 29th Meeting, pp. 415-421.

41 On Geological Contacts and Ancient Erosion in Southern and Central New Brunswick, L. W. Bailey. Proc. and Trans. of Royal Soc. of Canada for 1884, vol. n, sec. 4, 

1884, pp. 91-97.

4i Report on the Geological Formations of Eastern Albert and Westmoreland Counties, New Brunswick, and of Portions of Cumberland and Colchester Counties, Nova 

Scotia, R. W. Ells. Rept. of Prog. Geol. Survey of Canada for 1885, vol. i (new 

series), pp. 5-71 E. With a map.

43 On the Progress of Geological Investigation in New Brunswick, L. W. Bailey. 

Proc. and Trans. Royal Soc. of Canada for 1889, vol. vn, sec. 4,1889, pp. 3-17.

41 Matthew, G. F. President's Annual Address; Eozoon and Other Low Organisms 

in Laurentian Rocks at St. John; On the Occurrence of Sponges in Laurentian Rocks 

at St. John, N. B. Bull. Nat. Hist. Soc. of New Brunswick, No. 9, 1890, pp. 25-35, 

36-41, 42-45.

|6 Remarks on the Mineralogy and Geology of the Peninsula of Nova Scotia, Charles 

T. Jackson and Francis Alger; pp. 116. With a colored map.

16 On the Geology of Cape Breton, Richard Brown. Quart. Jour. Geol. Soc., London, 

vol. T, 1845, pp. 23-26, 207-213. With a geological map.

47 On the Metamorphic and Metalliferous Rocks of Eastern Nova Scotia, J. W. 

Dawson. Ibid., vol. vi, 1850, pp. 347-364. With a geological map of a part of Nova 

Scotia.

48 Acadian Geology, J. W. Dawson: 1st ed., 1855, pp. 388, with a map; 2d ed., 

1868, pp. 694, with a map; 3d ed., 1878, pp. 694, supplement, pp. 102, with a map. 

In the abstract the second edition is followed.
VANHISB.] EASTERN CANADA AND NEWFOUNDLAND. 255

49 Campbell: Nova Scotia Gold Fields, 1863.

50 Report on the Waverly Gold District. Henry Youle Hind; pp. 62. With geological maps and sections.

61 Eeport on the Sherbrooke Gold District, together with a paper on the Gneisses of 

Nova Scotia, Henry Youle Hind; pp. 79. With a geological map. See also On Two 

Gneissokl Series in Nova Scotia and New Brunswick, supposed to be the Equivalents 

of the Hurouian (Cambrian) and Laurentian. Quart. Jour. Geol. Soc., London, vol; 

xxvi, 1870, pp. 468-479, with plate; and On the Laurentian and Huroniau Series 

in Nova Scotia and New Brunswick, Am. Jour. Sci., 2d series, vol. XLIX, 1870, pp. 

347-355.

M Nova Scotia Mining Reports, vol. i (a series of reports by various authors upon 

mining regions of Nova Scotia, bound together; the majority of them by Benjamin 

Silliman), pp. 1-10.

63 Report on a part of the Pictou Coal Fields, Nova Scotia., W. E. Logan and 

Edward Hartley. Kept, of Prog. Geol. Survey of Canada from 1866 to 1869, pp. 1-107. 

Wtth a map.

64 Notes and Observations on the Gold Fields of Quebec and Nova Scotia, A. R. C. 

Selwyn. Rept. of Prog. Geol. Survey of Canada for 1870-71, pp. 252-282.

68 On Explorations and Surveys in Cape Breton, Nova Scotia, Charles Robb. Rept. 

of Prog. Geol. Survey of Canada for 1874-'75, pp. 166-266. With two geological 

maps.

66 Report of Explorations and Surveys in Cape Breton, Nova Scotia, Hugh Fletcher. 

Rept. of Prog. Geol. Survey of Canada for 1875-'76, pp. 369-418. With a geological 

map.

67 Report on the Geology of part of the Counties of Victoria, Cape Breton, and 

Richmond, Nova Scotia, Hugh Fletcher. Rept. of Prog. Geol. Survey of Canada 

for 1876-'77, pp. 402-456. With a map.

58 Acadian Geology, J. W. Dawson. Third ed., 1878, pp. 694, supplement, pp. 

102. With a map.

69 Report of Explorations and Surveys in Cape Breton, Nova Scotia, Hugh Fletcher. 

Rept. of Prog. Geol. Survey of Canada for 1877-'78, pp. 1-32 F. With a geological 

map.

60 Report on part of the Counties of Richmond, Inverness, Gnysborougli, and Autigonish, Nova Scotia, Hugh Fletcher. Rept. of Prog. Geol. and Nat. Hist. Survey of 

Canada for 1879-'80, pp. 1-125 F.

B1 Report on the Geology of Northern Cape Breton, Hugh Fletcher. Rept. of 

Prog. Geol. and Nat. Hist. Survey and Museum of Canada for 1882-'83-'84, pp. 1-98 

H. Geol. map of Cape Breton.

C2 The Geology of Capo Breton Island, Nova Scotia, Edward Gilpin. Quart. Jour. 

Geol. Soc., London, vol. XLII, 1886, pp. 515-526. With a geological map of Cape 

Breton.

63 Report on Geological Surveys and Explorations in the Counties of Guysborough, 

Antigouish, Pictou, Colchester, and Halifax, Nova Scotia, from 1882 to 1886, Hugh 

Fletcher. Rept. of Geol. and Nat. Hist. Survey of Canada for 1886, vol. 11 (new 

series), pp. 1-128 P. With two plates.

M Report on the Lower Cambrian Rocks of Guysborough and Halifax Counties, 

Nova Scotia, E. R. Faribault. Ibid., pp. 129-163 P.

65 On the Eo/oic and Paleozoic Rocks of the Atlantic Coast of Canada, in Comparison with those of Western Europe and of the Interior of America, J. W. Dawson. Quart. Jour. Geol. Soc., London, vol. XLIV, 1888. pp. 797-817, and note, vol. 

XLV, p. 80, Proc.

66 General Report of the Geological Survey of Newfoundland for the years 1839 and 

1840, J. Beete Jukes, pp. 160. Accompanied by maps.

CT The Geology of the Northeastern part of Newfoundland, Alexander Murray, 

Rept. of the Geol. Survey of Newfoundland for 1864, pp. 4-50.
256 PKE-CAMBEIAN ROCKS OF NORTH AMERICA. [BULL. 86.

'* An account of a part of the Coast of Notre Dame Bay, Alexander Murray. Rept. 

of the Geol. Survey of Newfoundland, pp. 111-136.

69 The Peninsula of Avalon, Alexander Murray. Rept. of the Geol. Survey of Newfoundland for 1868, pp. 137-186.

70 The Rocks of Bonavista Bay, Alexander Murray. Rept. of the Geol. Survey of 

Newfoundland for 1869, pp. 187-209.

 71 Examination of Sundry Parts of the Coast, James P. Howley. Rept. of the 

Geol. Survey of Newfoundland for 1870, pp. 210-249.

72 A Farther Account of the Avalon Peninsula, Alexander Murray. Rept. of the 

Geol. Survey of Newfoundland for 1872, pp. 279-297.

7:! The Country Surrounding St. George's Bay, Alexander Murray. Rept. of the 

Geol. Survey of Newfoundland for 1873, pp. 298-350.

74 Report of the Geological Survey of Newfoundland for 1874, pp. 351-409

 Tii Report of the Geological Survey of Newfoundland for 1876, pp. 423-462.

7ri Report of James P. Howley for the year 1881: Rept. of Prog, of the Geol. Survey 

of Newfoundland for the. year 1881, pp. 6-23. With geological maps of the peninsula of Avalon.

17 Sta'atigraphic Position of the Olencllus Fauna in North America and Europe, 

Charles D. Walcott. Am. Jour. Sci., 3d ser., vol. xxxvn, 1889, pp. 374-392; vol. 

xxxvin, pp. 29-42.
CHAPTER V.

ISOLATED AREAS OF THE MISSISSIPPI VALLEY.

SECTION I. THE BLACK HILLS. 

LITERATURE.

HAYDEN,1 in 1862, states that the nucleus of the Black hills consists 

of red feldspathic granites, with'stratified metamorphic Azoic slates and 

schists, upon which rests unconformably, forming a zone around the 

ellipsoidal nucleus, a series of reddish ferruginous sandstones, which, 

by their organic remains are shown to belong to the Potsdam. In the 

Potsdam are found as pebbles the different varieties of the changed 

rocks beneath.

HAYDEN,2 in 1863, describes the Black hills as an outlier of the Rocky 

mountains. They are formed of a granite nucleus surrounded by a 

series of Azoic highly metamorphosed strata standing vertical, and 

comprise slates, gneiss, syenite, quartzose and calcareous rocks.

HAYDEN, 3 in 1872, describes the Black hills as being the most complete illustration of an anticline not complicated by any other influences 

that he has found in the west. The nucleus is a massive feldspathic 

granite with a series of gneissic beds outside of it, which incline in 

every direction from this nucleus in a sort of narrow oval quaqiiaversal, 

and include all the unchanged beds known in this portion of the West 

from the Potsdam sandstones to the top of the Tertiary lignites.

WiNCHELL,4 in 1875, describes in the Black hills, below the Primordial sandstones and quartzites, a series of mica-slates and mica-schists 

which contain intercalated beds of quartz. These rocks often stand 

nearly vertical. In the neighborhood of the granite areas they are 

interstratified with beds of true granite, and with this granite is found 

tourmaline. The granite area is near the southern part of the hills and 

of this Harney peak may be taken as a center.

NEWTON,5 in 1880, gives a systematic account of the Black hills of 

Dakota. The Black hills is a geological area which is admirably circumscribed. They consist of a nucleal area of metamorphic slates and 

schists containing masses of granite, about which is an inward facing 

unconformable escarpment of Potsdam sandstone and Carboniferous 

limestone which dip away on all sides from the axis of the hills. The 

Archean rocks as a whole occupy an area of about 850 square niiles, 

being about 60 miles long and 25 miles wide at its maximum. At numerous points within the hills are centers of volcanic eruption of an age

Bull. 86 17

257-
258 PRE-CAMBEIAN BOOKS OF NOETH AMEEICA. [BULL. 86.

probably coincident with the elevation of the mountains. It is impossible to estimate with any degree of accuracy the thickness of the Archean 

schists, as they are highly inclined and distorted, and in their present 

metamorphosed and denuded condition it can not be determined whether 

they are the remnants of several great folds or whether they are the 

broken strata of one vast fold, though the latter seems to be the more 

probable structure; in which case the total thickness of the Archean 

strata must be more than 100,000 feet, about 25 miles. The examination showed no evidence of the duplication of any parts of the Archeau 

strata, and it is presumed, if a repeated folding has taken place, that it 

did not occur within the area exposed in the hills.

The Archean sedimentaries are divided into two groups, schists and 

slates. The schists include quartzose, garnetiferous, ferruginous and 

micaceous varieties, together with some gneiss, chloritic, talcose, and 

hornblendic schists, and quartzite. The schists are occasionally staurolitic. The whole series is coarse in texture, highly crystalline, and 

contains seams or veins of quartz conformable Avith the stratification 

and having a lenticular form. The slates are distinguished from the 

schists mainly by their fine and compact texture, although, as shown 

by Caswell, their ultimate mineral composition is similar. They are 

mainly micaceous clay-slate, siliceous slate and quartzite, which are 

sometimes associated with specular oxide of iron. On Box Elder creek 

is a ridge 400 feet in height, which is a vast deposit of siliceous hematite and resembles the siliceous hematites of the lake Superior regionThe quartzites of the two classes are similar. The mica-schist passes 

into chlorite-schist, siliceous schist and quartzite. The schists of the 

southern part of the hills are associated with an area of highly feldspathic granite which culminates in the region of Harney peak. On 

the outskirts of this district are many smaller masses of granite. So 

far as the structure was made out, each of the bodies has a lenticular 

shape and is intercalated among the strata of the schists. No granite 

is found associated with the slate. The general strike of the rocks is 

northwest and southeast. The topography shows that there is a series 

of ridges in this direction which mark the position of the particularly 

hard layers such as quartzites. The schists are found in the western 

and southwestern parts of the area and the slates in the east and northeast.

Between these two groups Jenney noted a distinct discordance of dip 

on Castle creek, but in the absence of corroborative observations the 

unconformity of the two series can not be insisted upon. The division 

of the system into two series is then based on lithological differences 

purely and is warranted on this ground. The lithological difference is, 

however, more a mineralogical one than chemical, being probably due 

to a difference in metamorphism. The apparent discordance discovered 

by Jeuney, and this lithological difference, gives strong support to the 

view that the slate and schist periods were separated by an interval of
U.S.GEOLOGICAL SURVEY. BULLETIN 86. PL. VII.

UNCLASSIFIED PRE-CAMB ALGONKIAN

SLATES & SCHISTS

POST-ALGONKIAN

GRANITE

GEOLOGICAL MAP OF PORTIONS OF MONTANA, IDAHO, WYOMING AND DAKOTA

SHOWING PRE-CAMBRIAN ROCKS 

Compiled from the Kin^Hayder^S: Powell Reports.

Scale 47sa.ooo.
VANHISB.] ISOLATED AREAS OF THE MISSISSIPPI VALLEY. 259

time between which there was erosion and metamorphism of the lower 

series. The granite is coarsely crystalline. It is concluded that, because of the great amount of feldspar in the granite, because pieces of 

schist are inclosed in it without any transition, because the granite 

masses in the schist have a long lenticular shape, because of the coarseness and evenly granular character of the granite, and because there is 

never any transition between the schist and granite, the latter is 

an eruptive rock in the schists. That the Archean rocks were upturned 

and metamorphosed before Potsdam time is shown by the fact that the 

basement conglomerate of the Cambrian contains fragments of slate, 

schist, and granite precisely like the underlying rocks.

Since the lithological character of the Black hills Archean is the only 

means of judging their affinities it should have some weight. The eastern slate division bearing the lean ores are very similar to the Huronian 

rocks of the south shore of lake Superior and Canada. The western 

schist series containing granite masses differs from the Huronian and 

from the Laurentian in that gneiss, the most characteristic rock of the 

latter, is nearly lacking, so that no correlations are made further than 

to call the slate series newer Archean and the schist series older 

Archean.

BLAKE,6 in 1885, on account of the presence of staurolite in the 

Black hills schists, places these formations as the probable equivalent 

of the Coos group of Hitchcock in New Hampshire, and it is said that 

there is sufficient breadth of formation to include all the rocks from the 

Huronian to the Coos.

CEOSBY,7 in 1888, finds that the two groups of Archean as mapped 

by Newton are quite sharply defined from each other. It is said that 

in the eastern series of slates are pebbles which have been quite certainly derived from the harder rocks of the western series. The strike 

of the schists is found to curve around the granitic and gneiss ic area 

and the normal dip of the strata is aVay from this nucleal granitic 

mass. A conglomerate is associated with the quartzite of the eastern 

slate area, the pebbles of which have suffered extensive deformation by 

compression. The granitic rocks of the schist area do not penetrate 

the slates of the newer series, although this is not devoid of eruptive 

rocks. The newer series of slates is correlated with the Taconian of 

Avestern New England. The conclusion is reached that the granite, 

instead of being of eruptive origin, is pegmatitic.

CARPENTER,8 in 1888, states that the unconformity supposed to exist 

by Newton between the eastern slate and western schist .series is supported by an observation upon Spring creek east of Hill city. A huge 

dike of igneous rock a thousand feet broad in places is described as 

passing through the entire length of the eastern series.

VAN HiSE,9 in 1890, finds that the prominent structures of" the Black 

hills, which have heretofore been taken as bedding, are secondary 

structures. As evidence of this is the fact that alternating bands of
260 . PRE-CAMBRIAN KOCKS OF NORTH AMERICA. [BULL.86.

sediments of different characters are seen to cut across the prominent 

lamination. Sometimes these belts are conglomeratic and the pebbles 

are deformed by pressure. The longer axes of the pebbles are parallel 

to the slaty or schistose structure, but the belts as a whole cut across 

.this structure. The fact cited by Newton that there are persistent belts 

of quartzite parallel with each other also indicates duplication by folding. The thickness of the Archean is then unknown, instead of being 

more than 100,000, as supposed by Newton. The crystalline schists 

are in a broad zone about the granite area, striking parallel to it and 

dipping away from it, and in the northern hills there are great quantities of later eruptives. Granite is found in the slate area as mapped 

by Newton.

A study of the boundary between the slate and schist series leads to 

the conclusion that there is a gradation from the slates to the schists 

rather than an abrupt change. The foliation of the schists about the 

granite is secondary and is caused by the contact and dynamic meta. 

morphism due to the intrusion of the granitic rock. The effect has 

extended for several miles from the main granite area. The normal 

foliation of the slates and schists is north and south, and this was produced by folding earlier than the intrusion of the granite. About the 

granite area both sedimentation and this earlier foliation were destroyed and a more prominent newer foliation produced. Als*o, in the 

northern part of the slates is a considerable area about Deadwood 

which is now as crystalline as the schist area of the south. This is 

taken to be due to the abundant later intrusives here found. We 

thus have in this region evidence of an original bedding which is nearly 

obliterated by a prominent slaty cleavage, and both of these have been 

wholly destroyed for considerable areas by a newer and more prominent schistose structure. The slates and schists can not then be divided into two series with the surface distribution and upon the lithologicat differences given by Newton.

The mica slates, mica-schists, and mica-gneisses are found to be 

clastic rocks, the processes of change from their original clastic condition to their present crystalline one being traced out. Associated 

with the clastic rocks are other green crystalline schists which are 

metamorphosed basic eruptives which were probably intruded before 

the earlier folding of the slates. Corroborating Newton's conclusion, 

it is said that the Black hills rocks exhibit a remarkable lithological 

analogy to certain of the iron-bearing series of the lake Superior region, 

which in the past have been included under the term Huronian. While 

this correlation is not beyond doubt, there is no question that these 

series in common belong to the Algonkian.

SU.MMAKY OK UKSULTS.

The summary of Newton's work is altogether unsatisfactory because 

of the very large amount of material contained in this report. The
VAN BISK.] ISOLATED AREAS OP THE MISSISSIPPI VALLEY. 261

descriptions in the original are condensed, and to include all which, 

bears upon structural relations would greatly extend the digest given. 

In the light of the present facts it would seem that we have in the 

Black hills a set of slates and schists as yet of unknown thickness and 

undivided into series, although perhaps capable of subdivision by closer 

work. These slates' and schists have a prominent cleavage which is 

independent of the structure. The different parts of the area vary in 

degree of crystallization, and this crystalline character is due to the 

intrusion of igneous rocks; but, unlike ordinary contact metamorphism, 

has extended from the granitic areas for a distance of several miles. 

For the present we are obliged to consider the whole as a single series. 

In the alternating slaty and quartzose characters of the rocks, in the 

presence of siliceous hematite and a much folded condition, the present

structures being in a vertical attitude, they more nearly resemble the

Lower Huronian of the lake Superior region than any other rock series, 

 but this is not sufficient warrant for the positive conclusion that the 

two are time equivalents. The correlation of the Black hills rocks with 

the Taconic on slight lithological evidence as is done by Orosby, or a 

part of them with the -Coos group on account of the presence of staurolite, can be considered as no more than guesses.

SECTION II. MISSOURI.

LITERATURE.

KING, (H.),10 in 1851, states that the Primitive formation is met with 

near a point about 70 miles south of St. Louis and 30 miles west of the 

Misissippi. It consists chiefly of granite, syenite and porphyry, and rises 

in cone-like elevations or detached ridges to the height often of 1,000 or 

1,200 feet above the level of the Mississippi river. Its sides and valleys 

are frequently covered with sandstone and limestone in such quiet relationship as to show that their deposition has taken place since the 

Primitive rocks assumed the form they now have. It is not at all unusn;il to tind portions or fragments of the older rocks imbedded in those 

that are stratified. This occurs both in the lowest magnesian I imestone 

and in the overlying sandstone. The Primitive rock is broken through 

by greenstone dikes which reach the surface of this ror/k, yet never 

penetrate the overlying sandstone. At Iron mountain is a layer'of 

specular oxide of iron, below which, at one place is a stratified rock 

which may have been a modified granite. The iron-ore deposit is often 

in the form of pebbles of various sizes up to a foot in diameter. In the 

interstices of these, pebbles is a reddish brown clay. The bed of iron 

in the thickest point opened is 20 feet. At the summit of Pilot knob 

is an immense mass of solid ore which is associated with porphyry and 

appears to pass by insensible gradations into that rock.

WntTNEY, 11 in 1854, describes Iron mountain and Pilot knob as 

localities in which are found eruptive ores of Azoic age. Iron nioun-
262 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [nntt.80.

tain is a flattened dome-shaped elevation, composed of feldspathic 

porphyry. The surface of the mound is covered with loose pieces of 

ore, which is in some places in a layer at least 15 feet thick. Pilot knob 

is mainly composed of dark siliceous rock, distinctly bedded, dipping- to 

the south at an angle of 25° or 30°. For about two-thirds of its height 

of 650 feet quartz rocks predominate. Above that, iron is found in 

heavy beds alternating with siliceous matter.

SWALLOW/2 in 1855, describes the granite, greenstone, and porphyry 

of Missouri as igneous rocks. Bed feldspathic granite, sparingly 

micaceous, occurs in Sec. 15, T. 34 N., B. 3 E. Nearly all of the hills 

and ridges in the neighborhood of Iron mountain and Pilot knob are 

wholly or in part formed of compact reddish-purple feldspathic porphyry. 

The porphyry is one of the oldest rocks of the state, but no opportunity 

occurred for determining whether it is older than the granite, although 

there is no doubt that it is older than the greenstone, as the latter 

rock is said to occur in dikes in the porphyry. The porphyry is older 

than the stratified rocks of the region because they are found resting 

upon knobs and ridges of porphyry in a position so nearly horizontal 

as to preclude the idea that they were deposited before the upheaval 

of the principal masses which form the hills. Whether the slates interstratified with the iron near the top of Pilot knob are older is not 

easily determined.

SWALLOW, 13 in 1859, states that in one locality in Laclede and in one 

or two in Crawford county are granite dikes or ridges which rise 

above the stratified rocks.

HARRISON, U in 1868, describes two localities in Washington county, 

where between the horizontal limestone and the solid porphyry are 

conglomerates consisting of water-worn pebbles and bowlders all of 

porphyry, cemented together by a calcareous matrix. Interstratitied

with the limestone are also thin layers containing Avater-worn porphyry 

pebbles. It is therefore concluded that the porphyry hills existed as 

such before the Silurian hills were deposited.

PUMPELLY, 15 in 1873, states that the Archean (Azoic) rocks of southeastern Missouri form an archipelago of islands in the Lower Silurian 

strata which surrounds them as a whole and separates them from each 

other. They appear as knobs 1,400 to 1,800 feet above the sea, and 

rising 300 to 700 feet or more above the valleys. The rocks consist 

chiefly of granites and felsitic porphyries. They reach their most extensive surface development in the region forming the northern part of 

Madison, Iron, and Eeynolds, and the southern part of St. Francis and 

Washington counties. This series is the near equivalent in point of 

age to the iron-bearing rocks of lake Superior, New Jersey, and Sweden. 

The rocks overlying them belong to the oldest known members of the 

Silurian, but they may be the deep-seated equivalents of the Potsdam 

sandstone or even older. Before the deposition of the Silurian the porphyries and granite had undergone an enormous amount of erosion, an
VANHISE.] ISOLATED AEEAS OF THE MISSISSIPPI VALLEY. 263

amount at least several times as great as they have suffered since that 

remote time.

The surface of Iron mountain has disintegrated and decomposed in 

mass, the entire porphyry-hill being changed to a clay. Disintegration 

has often taken place to a depth of certainly more than 50 feet in the 

granites of Madison county. The iron ore of Iron mountain is a residuary deposit, having its origin in the gradual removal of the existing 

crystalline rocks and leaving behind the iron ore.

Pilot knob is composed of more or less massively bedded porphyries, 

porphyry-conglomerates, and beds of hard specular ore. These strata 

strike K 50° W., and dip ou an average 13° southwest by south. The 

top of the knob consists of stratified porphyry conglomerate with a 

thickness of 140 feet. This rock is made up of small and large, more 

or less angular, pebbles of porphyry cemented together by iron ore and 

containing frequent layers and bodies of ore. At the base of this series 

is a great bed of ore divided into two parts by a thin slate seam. Immediately below the ore is porphyry, which continues to the base of 

the hill.

The rocks forming the southwestern flank of Cedar hill are the extension of the conglomerates and ore beds of Pilot knob. Manganese ores 

are found associated with the porphyritic rocks, and in Sec. 16, T. 33 

N., K. 2 E., in Beynplds county, the manganese ore is one of the members of a series of bedded porphyries. At this locality metainorphic 

limestone is one member of the porphyry series, but it is now by physical 

and chemical agents greatly changed from its original condition, and is 

very manganiferous. Another member of this same succession is a porphyry-conglomerate or breccia, consisting of pebbles of red and compact porphyry containing grains of quartz and crystals of feldspar, and 

cemented by porphyry of a similar character. This rock resembles the 

Calumet-Hekla conglomerate of lake Superior.

ScHMiDT, 16 in 1873, also describes the iron-ore deposits of Iron mountain, Pilot knob, Shepherd mountain. Cedar hill, Buford hill, Big Bogg 

mountain, Lewis mountain, Cuthbertson bank, and Hogan mountain. 

The succession at Cedar hill includes slates of red-banded porphyry, 

stratified quartz-porphyry, slates of red porphyry, green porphyry, 

banded jasper, and jasper with specular ore.

SHUMARD, 17 in 1873, states that granite is found in Laclede, Crawford, and Ste. Genevieve counties.

BROADHEAD and NORWOOD," in 1874, describe granite and porphyry 

at numerous points in Madison county. On the west side of St. Fran- 

£ois river in the NW. J of NE. J Sec. 33, T. 34 K., E. 5 E., there is an 

exposure of sandstone and conglomerate resting directly on the granite.

HAWORTH,19 in 1888, states that the Archean area of Missouri covers 

an irregularly outlined portion of no less than ten different counties and 

extends to the west as far as Texas county, to the north and northeast 

as far as Washington, St. 'Francois and Ste. Genevieve; to the east
264 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

it passes through Madison, county, and to the south nearly through 

Wayne county, but only a small portion of this territory is covered by 

Archean rocks. The rocks are the different kinds of porphyry, which 

predominate, granite, and dikes of diabase and diabase-porphyry. 

Numerous instances were observed where the stratified rocks overlie 

the massive ones and are nonconformable with them. Nowhere at the 

contact zone was metamorphosed limestone or sandstone observed. 

The granites, so far as observed, occur on low ground, while the hills 

are almost invariably composed of porphyry. At numerous places 

dikes of various sizes occur, sometimes in the granite, and sometimes 

in the porphyry, and, as stated by Broadhead, sometimes in the sandstone. Detailed descriptions are given of the granites, porphyries, and 

dike rocks.

HAWORTH, 20 in 1891, describes the crystalline rocks in the vicinity 

of Pilot knob, Missouri. These are chiefly porphyries, felsites, and 

breccias. These rocks are regarded as Archean in age, because there 

is no contact metamorphism between them, and the surrounding Paleozoic rocks, and because in the Paleozoic sandstones and limestones are 

numerous fragments of the crystalline rocks. The crystalline rocks are 

regarded as of eruptive origin, as shown in the field by the absence of 

bedding, by flow structure, by banded structure, by lithophysae, by 

breccia, by scoria, by amygdaloids, by tuffs, and by absence of gradations into noncrystalline rocks, and as shown by the microscope, by 

the texture of the groundmass in the porphyries and breccias, by flow 

structure in them, by magmatic corrosion of porphyritic crystals and 

fragments of the breccias, and by other phenomena. The laminated 

ferruginous rocks of Pilot knob and of other localities are regarded as 

volcanic breccias. As evidence of this it is said that this material

passes into the porphyry, that the fragments are all of porphyry or

felsite, and that the groundm asses of the breccias or conglomerates are 

always felsitic or porphyritic, the apparent detrital fragments being 

merely set in a lava of a similar character.

PUMPELLY and YAN HiSE,21 in 1890, find that at Iron mountain 

the ore (specular hematite), in its original position, occurs in the form 

of veins in the porphyry. These veins are sometimes of very considerable thickness, running as high as 30 feet. They vary from this size 

to those much smaller, ramifying through and cutting the porphyry in 

various directions. In some places on the mound between the stratified 

sandstone and the porphyry is a pre-Silurian mantle of detrital material, which is largely composed of fragments of the vein ore. The chief 

mining at the present time is from a mass of bowlders of the iron ore 

in a pre-Silurian ravine. In the process of disintegration the more resistant and heavier masses of iron ore have been concentrated in the upper 

slopes of the ravine, forming a deposit analogous to. a placer. The vast 

amount of this iron ore in these ravines, as well as that which occurs as a 

residuary deposit upon the mound, indicates that in pre-Silurian time
VANHTSE.] ISOLATED AREAS OP THE MISSISSIPPI VALLEY. 265

there was here an enormous erosion in order that this quantity should 

accumulate from the relatively sparse and small veins of iron ore in the 

mountain. The Pilot knob iron-ore bed was found to grade upwa.rd into 

a conglomerate, the matrix of which is largely composed of ore and 

the most of the pebbles of which are porphyry. The whole appearance 

of the deposit is that of a detrital one, and the question arises whether 

this bed has been produced from the erosion of earlier vein deposits 

in the porphyries, such as are found in Iron mountain. Pilot knob itself 

bears the same relations to the Silurian as does Iron mountain, and if 

this suggestion as to the origin of the Pilot knob ore is correct, it implies that the pre-Silurian history has not only been very long, but complex.

SUMMARY OF KKSULTS.

As the crystalline rocks of central Missouri are islands surrounded 

by Cambrian sediments, Ave have no definite means of determining their 

age except that they were in their present condition and deeply eroded 

before the overlying rocks were deposited. With a considerable degree 

of probability they may therefore be referred to the pre-Cambrian. The 

series is mainly an eruptive, porphyritic one, but the lavas are oftentimes bedded* The elastics are sometimes porphyry-conglomerates, 

the materials of which have evidently been derived from the underlying porphyry flows. At Pilot knob the iron ores are associated with 

the conglomerates.

There is, then, in central Missouri a pre-Cambrian clastic series, and 

therefore a member of the Algonkian system. Whether any of the 

crystalline rocks-are older than the Algonkian there is no certain means 

of judging. There are also no certain data upon which to parallelize 

this Algonkian series with the Algonkian series of the nearest preCambrian region, that of lake Superior. Upon the whole, the lithological character of the series more nearly resembles tharfc of the Keweenawan than any other, although it has a very considerable likeness 

to the Upper Hnronian. This is indicated by the porphyries and porphyry-conglomerates, while the analogy with the Upper Huronian is 

indicated by the beds of iron ore. This comparison is rather strengthened by the fact that the Upper Huronian quartzite outcrops of southern Wisconsin are associated with and cut by porphyries. But a reference of the Missouri rocks either to the Keweenawan or Upper Huronian has a very uncertain value, and it is not impossible that it rather 

represents the period of erosion which separates the Keweenawan and 

Upper Huronian, since in lithological characters it combines to a considerable extent those of these two series.
266 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

SECTION III. TEXAS. 

LITERATURE.

BoEMER,22 in 1848, mentions granitic rocks at several points, 15 miles 

north of Fredericksburg, on the banks of the Llano, in the country 

between the Llano and San Saba, and between the Piedernales imd Hau 

Saba rivers. These granitic rocks are surrounded by Paleozoic strata.

SnuMARD,23 in 1860, describes in Burnet county rocks upon which 

rest directly the fossiliferous Potsdam.

SnuMARD,24 in 1861, describes the Primordial rocks of Texas as 

resting upon reddish feldspathic granite very similar in character and 

composition to the granites of Iron mountain, Missouri.

BuCKLEY,25 in 1866, states that the known Azoic rocks of the state 

are mostly in Llano and adjoining counties. There are here granites 

with steatite or soapstoue, immense beds of iron ore, and metamorphic 

rocks, consisting chiefly of slates, mica-schist and gneiss with quartz 

veins. The granites of Burnet county probably belong to a laterperiod 

of elevation than the Azoic. Here the metamorphic rocks are on the 

outskirts of the granite, in nearly vertical, more or less broken or contorted strata. In Mason county are highly inclined micaceous shales. 

At Packsaddle mountain are dark shales which, near Honey creek, extend unconformably beneath the nearly horizontal layers of Potsdam 

sandstones and limestones. In Mason county is a very large deposit of 

iron ore, which is believed to be a true vein. Another bed of iron ore 

lies between two granite ridges and is traversed by veins of quartz. 

House mountain, consisting of granite, is capped by massive beds of 

nearly horizontal sandstone. The Azoic rocks trend in a north east and 

southwest direction, being on the same line of upheaval as the Ozark

mountains of Arkansas and the Iron mountains of Missouri.

BucKLEY,2" iu 1874, describes as resting unconformably beneath the 

Potsdam, in Llano county, shales and argillites which lithologically 

resemble the old slates of Vermont and New Hampshire. They are 

barren of fossils. Locally a slaty cleavage is developed. Sometimes 

the slate is changed into a gneissoid rock, all gradations of the change 

being seen. Friable mica-slates containing garnet sometimes underlie 

the granite. These rocks are referred to the Laurentian. Most, and 

probably all, of the granites of this region are of a later period than the 

metamorphic rocks associated with them. Associated with the granite 

in Burnet and Llano counties are immense beds of magnetic iron ore.

BuCKLEY,27 in 1876, describes Azoic granitic rocks in many of the 

mountain ranges west of the Pecos river. At a number of places basaltic rocks occur. All the igneous rocks north of the Pecos are either of 

upper Cretaceous or Tertiary age, as is shown by the uptilted strata of 

these rocks.

WALCOTT,28 in 1884, finds that the Potsxlam sandstone rests unconformably on a great formation to which the term Llano group is applied.
ISOLATED AftEAS OP THE MISSISSIPPI VALLEY. 267

These rocks are alternating bods of sandy shales, sandstones, limestones, and schists that have a dip from 15° to 40°. They are little 

metamorphosed. The overlying sandstone in. its fossils is like the 

Tonto group of the Grand canyon, and the Llano group is correlated 

 with the Grand canyon and Ohuar series of the Grand canyon on the 

basis of position and lithological character. The best exposures are 

at Packsaddle mountain, in Llano county, where the horizontal Potsdam rests on the uptilted and eroded Llano beds. Across the valley 

of Honey creek, 4 miles west of Packsaddle mountain, the strata of 

the Llano group have been more metamorphosed, plicated, and broken 

by intrusive dikes of granite. The intrusive rocks are of pre-Potsdam 

age, but largely the result of extrusion of granite at or near the close 

of the erosion of the Llano. They are the chief cause of the metamorphism of the Llano rocks. No rocks of undoubted Arcliean age were 

observed.

SnuMABD,29 in 1886, describes as eruptive rocks the granites, porphyries and basic rocks which compose the whole of Wichita, Limpea,- 

Hueco, and Mimbres mountains. In the Organ mountains are partly 

sedimentary and partly eruptive rocks; while the Guadalupe, Sacramento, and Horse mountains are wholly sedimentary. None of these 

crystalline rocks are regarded as pre-Oambrian.

GLENN30, in 1890, describes the Azoic rocks as consisting principally 

of red granite, occasionally gneissoid, intersected by numerous nearly 

vertical dikes of quartz rock. West of the granite in Llano county is 

ah extensive field of schist, sandstone, and limestone of uncertain age. 

At Spring creek, in Burnet county, is also a small schist formation succeeding the granite. Were it not for the interposition of sandstone 

between the granite and the schists they would be assigned to the 

Azoic.

CoMSTOCK31 , in 1890, divides the Arcliean rocks of central Texas into 

a Burnetan (Laurentian?) system and Fernaudan (Ontaria.n ?) system.

The fundamental gneisses of the Burnetan occupy a lens-shaped area 

striking "N". 75° W., and they are well exposed in Burnet county. Within 

the group there are no unconformities. The rocks of the system are 

largely gneisses, but they graduate upon the one hand into qnartzose 

mica-schists, and upon the other into friable sandy gneisses and finegrained binary granites and graphic granite. Stratigraphically the. 

group is divided into three series from above downward, (1) B >deville, 

consisting of mica-schist and chlorite-schists (chiefly acidic); (2) Long 

mountain, consisting of hornblendic and pyroxenic rocks (basic)'j (3) 

Lone grove, consisting of gneiss, granite, etc. These rocks are compared 

with Lawson's lake of the Woods Archean. The igneous eruptions of 

the Burnetan are of different ages, some of them earlier and some later 

than the Potsdam.

The "Fern an dan or Ontariaii system is well exposed along the valley 

of San Fernando creek. Its exposures are more extensive than those
268 PRE-CAMBRIAN HOOKS OP NORTH AMERICA. (BULL.86.

of any other pre-Cambrian system. While in tlie main there is little 

difficulty in distinguishing between the Fern an dan and Burnetan strata, 

metamorphism has caused a close resemblance in many exposures. 

The general succession from above downward is calcareous rock, ehloritic slates and shales, carbonaceous schists, ferruginous rocks, quartzites, acidic schists, and basic schists. In this system are various eruptives, including granites, quartz dikes, and basic rocks. Whenever the 

Fernandan beds are visible in connection with the Burnetan strata, 

through their own excessive erosion or by reason of the persistence of 

prior elevations of the earlier system, there is always abundant evidence 

of unconformity 5 and if any fractures occur the joints of the northwest 

(Fernandan) trend invariably cross and cut the strike of the Burnetan 

rocks. Additional support for the unconformity of the two systems is 

gained from the fact that contortions occur in the lower system only 

where this or later trends affect its continuity. Moreover, the composition and texture of the Fernandan beds are to a large extent that of 

derivatives of the Burnetan lithologic series.

Above the Fernandan system is an Bparchean group of rocks, the 

stratigraphical affinities of which are nearer the Archean than the 

Cambrian. There is no doubt that they rest uu con form ably below the 

Paleozoic. To this group, including Walcott's Llano group, is given 

the term Texan (Algonkian?) system. The rocks of the Texnn system 

are chiefly siliceous, but shales and limestones are not wanting. The 

succession includes from the base upward a set of micaceous sandstones, with thinly laminated shales and chloritic detrital material; 

hard, white laminated quartz rock or quartz ite, associated with ferruginous and schists layers; .ferruginous shale beds, in part somewhat 

graphitic, and limestones or marbles. It is often difficult in the field 

to distinguish the graphitic shale and marble, as a belt, from the similar lithologic set of the earlier Fernaudan system. In hand specimens, 

however, the distinction is obvious. The Texan beds are much less 

altered, as a rule. The graphitic strata are plainly derivatives of the 

preexisting graphite schists, and the marbles are white or brdwn, instead of blue. The Packsaddle marbles and shaly beds are compared 

with the Ohuar; the Llano quartzites and sandstones, with eruptives, 

to the Grand canyon, and the Mason sandy shales and schists to the 

Vishnu series.

There must have been a vast amount of erosion after the folding of 

the Texan strata and prior to the deposition of the Cambrian sediments upon the upturned edges. The outcrops of the Texan strata are 

almost invariably accompanied by some of the Fernaudan beds, or by 

members very closely resembling these, often in such relations as to 

make it difficult to determine the boundary between the two groups 

upon structural grounds alone; but the rocks here included as of the 

Texan system are never involved in an earlier uplift than the northsouth trend.
VAN HIM.] ISOLATED AREAS OF THE MISSISSIPPI VALLEY. 269

COMSTOCK, 32 in 1891, further describes the relations of the pre-Cambrian rock series of central Texas. The Fernandian system is held to 

rest unconformably upon the Burnetian, because no other terranc 

within the Burnetian has structural, planes or breaks following a course 

N. 75° W., while every other axis of uplift is traceable through the 

rocks of the Burnetia.ii system, and because the basal members of the 

Fernandian system are made up in part of material apparently derived 

from the Burnetian rocks. That the Texiau (Algonkian 1?) system rests 

unconforraably upon the Fernandian is concluded from facts of the 

same character as those which show the discordance between the Burnetian and Fernandian. The nearly due north-south strikes of these 

rocks are commonly peculiar to them, the earlier fractures and lines of 

uplift being- invariably absent, but the later ones can be more or less

distinctly traced through the members of this system. There are localities exhibiting the juxtaposition of the Texian with the underlying 

Fernandian, in which the nonconformability between the two is seen. 

Tliese relations are seen south and southeast of Packsaddle mountain, 

southwest of Sharp mountain, in portions of the country north of Lockhart mountain, north and northeast of Mason, in the Beaver creek valley, and elsewhere in Mason county. Further, the derivative character 

of .the Texian beds is a marked feature. In the Fernandian is a great 

development of magnetites. While these deposits appear to be in discontinuous lenses or bosses across the region, there is almost always an 

indication of continuity in the shape of a line of ferruginous soil or 

other landmark. The iron deposits have above them carbonaceous and 

calcareous beds and below them quartzose beds.

SUMMARY OF RESULTS.

It appears that in central Texas there are two thick series, of clastic 

origin which are of pre-Cambrian age. The upper is Walcott's Llano or 

Comstock's Texiau, and the lower Comstock's Fernandian. The first 

of these is but little altered, the second is considerably metamorphosed 

and has associated with it a greater quantity of eruptive rocks. Between these series it is asserted by Oomstock that there is a great unconformity, as shown by numerous contacts, by Fernandian debris in 

the Texian, and by the fact that the Texian rocks are never involved 

in the earlier uplifts which have affected the Fernandian.

The Archean is represented by the Burnetian. Between the Burnetian and the Fernandian an unconformity is maintained by Comstock 

upon essentially the same grounds as between the Texian and Fernandian 5 that is, there are unconformable contacts between the series 5 the 

Fernandian bears debris from the Burnetian, and the Burnetian has 

been affected by orographic movements which are earlier than the FernandiaUe
270 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

NOTES.

1 The Primordial Sandstone of the Rocky Mountains in the Northwestern Territories 

of the United States, F. V. Hay den. Am. Jpur. ScL, 2d ser., vol. xxxm, 1862, pp. 68-79. 

See also Sketch of the Geology of the Country about the Head Waters of the Missouri 

and Yellovvstone Rivers. Ibid., vol. xxxi, 1861, pp. 229-245. Geological Report of 

Explorations of the Yellowstone and Missouri Rivers. 174 pp., with a geological map.

2 On the Geology and Natural History of the Upper Missouri, F. V. Hayden. Trails. 

Am. Phil. Soc., vol. xn, new series, 1863, pp. 1-218. With a geological map. See also 

Explanations of a second edition of a geological map of Nebraska and Kansas, based 

upon information obtained during an expedition to the Black Hills, under the command of Lieut. G. K. Warren. Proc. Acad. Nat. Sci., Philadelphia, vol. x, 1859, pp. 

139-158.

3 Report of F. V. Hayden. Preliminary Report of the U. S. Geological Survey of 

Wyoming, and portions of contiguous territories (being a fourth annual report of 

progress), pp. 1-188. See also Notes on the Geology of Wyoming and Colorado Territories. Proc. Am. Phil. Soc., vol. n, 1871, pp. 25-56.

4 Geological Report on the Black Hills of Dakota, N. H. Winchell. Report of a 

Reconnaissance of the Black Hills of Dakota, made in the summer of 1874, by William 

Ludlow, pp. 21-66. With a geological map.

6 Report on the Geology and Resources of the Black Hills of Dakota, Henry Newton 

and Walter P. Jenney. U. S. Geog. and Geol. Survey of the Rocky Mountain Region, 

566 pp. with atlas.

6 Tin Ore in the Black Hills of Dakota, William P. Blake. Mineral Resources of 

the United States for 1883 and 1884, pp. 602-613.

7 Geology of the Black Hills of Dakota, W. 0. Crosby Proc. Bos. Soc. Nat. Hist., 

vol. XXIH, 1884-1888, pp. 488-517.

8 Notes on the Geology of the Black Hills, Franklin R. Carpenter. Preliminary 

Report of the Dakota School of Mines upon the Geology, Mineral Resources, and 

Mills of the Black Hills of Dakota, pp. 11-52.

9 The pro-Cambrian Rocks of the Black Hills, C. R. Van Hise. Bull. Geol. Soc. of 

America, vol. I,pp. 203-244.

10 Some Remarks on the Geology of the State of Missouri, Dr. H. King. Proc. Am.

Assoc. Adv. Sci., 1851, 5th Meeting, pp. 182-201.

11 The Metallic Wealth, of the United States, J. D. Whitncy. Philadelphia-, 1854, 

510 pp.

12 First and Second Annual Reports of the Geological Survey of Missouri, G. C. 

Swallow. 1 Jefferson City, 1855, 207, 239 pp.

13 Geological Report of the country along the line of _the Southwestern Branch of 

the Pacific Railroad, State of Missouri, G. C. Swallow. St. Louis, 1859, pp. 93, with 

map.

14 Age of the Porphyry Hills of Southeast Missouri, Edwin Harrison. Trans. St. 

Louis Acad. -Sci., vol. li, p. 504.

lft Geology of Pilot Knob and its vicinity, Raphael Pumpelly. Preliminary Report 

on the Iron Ores and Coal Fields from the field work of 1872. Part 1, pp. 3-28.

lfi lron Ores of Missouri, Adolph Schmidt. Ibid., Part 1, pp. 45-214.

17 Reports on the Geological Survey of the State of Missouri, 1855-1871, B. F. Shumard. Jefferson City, 1873, pp. 189-323.

18 Madison County, G. C. Broadhead and J. G. Norwood. Report of the Geological Survey of the State of Missouri, including field work of 1873-'74, pp. 342-379, 

with an atlas.

|1J A Contribution to the Archean Geology of Missouri, Erasmus ITaworth. Am. 

Geol., vol. i, 1888, pp. 280-297, 363-382.

20 The Age and Origin of the Crystalline Rocks of Missouri, Erasmus Haworth. 

Geol. Survey of Missouri, Bull. No. 5, pp. 5-42.
VANHISE.] ISOLATED AREAS OF THE MISSISSIPPI VALLEY. 271

31 Based on unpublished field notes made by Profs. Raphael Purapelly and C. R. 

Van Hise, in the summer of 1890.

32 Contributions to the Geology of Texas, Dr. Ferdinand Roenier. Am. Jour. Sci. 7 

2d ser., vol. vi, 1848, pp. 21-29. See also Texas, etc., Dr. Ferdinand Roemer, 1849, 

pp. 464, with a map.

23 Letter, B. F. Shumard. Trans. Acad. of Sci. of St. Louis, vol. I, 1860, pp. 672-673.

24 The Primordial Zone of Texas, with descriptions of New Fossils, B. F. Shumard. 

Am. Jour. Sci., 2cl set., vol. xxxii, 1861, pp. 213-221.

28 A Preliminary Report of the Geological and Agricultural Survey of Texas, S. B. 

Buckley. Austin, 1866, pp. 81,4.

26 First Annual Report of the Geological and Agricultural Survey of Texas, S. B. 

Buckley. Houston, 1874, pp. 142.

27 Second Annual Report of the Geological and Agricultural Survey of Texas, S.' B. 

Buckley. Houston, 1876, pp. 96.

28 Note on the Paleozoic Ro.cks of Central Texas, Charles D. Walcott. Am. Jour. 

Sci.; 3d ser., vol.xxvm, pp. 431-433.

29 A Partial Eoport on the Geology of Western Texas, Prof. Geo. G. Shumard. Austin, 1886, pp. 145.

:i° A Preliminary Report on the Geology of the State of Texas, John W. Glenu. 

First Annual Report of the Geological Survey of Texas, 1889, E. T. Dumble, State 

geologist, pp. 245-246.

 "" Preliminary Report on the Geology of the Central Mineral Region of Texas, Theo. 

B. Conistock. Ibid., pp. 239-391.

 ^Report on the Geology and Mineral Resources of the Central Mineral Region of 

Texas, Theo. B. Conistock. Second Ann. Ropt. Geol. Survey of Texas, 1890, E. T. 

Dumble, State geologist, pp. 553-664, 2 maps.
C H A P T B E VI.

THE CORDILLERAS.

SECTION I. LARAMIE, MEDICINE BOW, AND PARK RANGES IN SOUTHERN WYOMING.

, LITERATURE.

STANSBURY,' in 1853, states that in the Black hills (Laramie) is an 

extensive formation of massive red feldspathic granite with occasional 

outcrops of ferruginous quartz.

HAYDEN,2 in 1803, describes the Laramie hills as consisting -of numerous centers of uplifted granite upon the sides of which the Carboniferous limestones are scattered or imconformably overlie. There is 

every gradation from unchanged fossiliferous limestoue to completely 

metamorphosed rock, melted material sometimes being found thrust into 

the seams of the unchanged mass." The core of Laramie peak is of 

granite, while, as if thrown off by this nucleus, is a series of Azoic stratified rocks consisting of gneiss, hornblendic, micaceous, and talcose 

slates, syenite, and quartz, which are cut here and there by dikes of 

trap or basalt.

HAYDEN,3 in 1868, mentions granites and syenites as occurring in the 

Laramie and Medicine bow ranges. On the east side of Laramie range, 

especially near fort Laramie, are seen the distinctly discordant relations between the crystalline rocks of the mountain range and tlie 

in imetainorphosed strata.

HAYDEN,4 in 1872, describes on one of the branches of the Chugwater, in the Laramie mountains, as occurring interstratified with red 

feldspathic granite, beds of magnetic ore which resemble the lake Superior iron ores. The rocks between the headwaters of the Chugwater 

and Laramie consist of beds of quartz, black gneiss, seams of feldspar, 

with, now and then beds of massive granite. On approaching the 

mountains the red feldspathic granite is found in great ridges, the 

gneissic strata diminishing and the massive granite increasing in approaching the mountain range.

ENGELMANN,5 in 1876, finds that the Laramie peak system consists 

of the igneous rocks, granite and granitic syenite. Among the igneous 

rocks are also greenstones, which are of later date than the granite in 

which they frequently are dikes.

HAGUE,6 in 1877, gives detailed descriptions of the Laramie, Medicine bow, and Park ranges. The Archean rocks of the Laramie hills 

272
VANHISB.] THE CORDILLERAS. 273

are classed under granites, gneiss, mica schist, and- hornblende schist, 

the first covering mnch the largest area. The central body consists of 

coarse grained granite. Above this, and forming the outer edges, dip 

ping east and west awayfrom the main mass, occur heavily bedded granitoid rocks. At the north and south ends of the range the granites gradually pass into well denned gneisses and schists, there being the most 

gradual transitions from the massive granites to the thinly laminated 

schists. Among the crystalline rocks is a variety of gabbro in the region of Iron mountain, Chugwater, and Horse creeks, where it forms 

knobs and knolls protruding through the granitoid rocks. At Iron 

mountain, north'of Chugwater creek, are masses of titaniferous iron 

ores incased in the granite. No large bodies of eruptive granites were 

scun nor eruptive rocks younger than the Archean. In structure the 

Laramie hills are regarded as a broad anticline, accompanied by many 

secondary folds. There is no case of decided nonconformity in the 

entire series of beds, and their uniform character indicates that they 

all. belong to one division of the Archean, which without doubt is the 

Laurentian. The sedimentary rocks of the eastern foothills everywhere rest uncouformably upon the Archean crystallines. East of 

Table mountain is the only outlying mass of Archean granite occurring 

eastward of the sedimentary foothills.

The second great range of the Rocky mountains the Medicine bowlike the Laramie range, is made up almost exclusively of Archean crystalline rocks. In their general habit they resemble the formation of 

the eastern range, but additional varieties are found. The rocks 

include granite, gneiss, hornblende-schist, mica-schist, dioritic schist, 

slate, argillite, quartzite, chert, horn stone, conglomerate, and limestone. 

The larger bodies of true granite are confined to the southern end of 

the range, where it is closely connected with the Front range of Colorado. Even this granite shows more or less tendency to bedding, the 

constituent minerals being arranged in parallel layers. From Brush 

creek northward 15 or 20 miles are light colored mica-gneisses and dark 

hornblende-schists, with occasional beds of vitreous quartzite. Medicine peak is a mass of pure white quartzite rising 2,000 feet above the 

surrounding country. The main ridge has a trend approximately north 

20° east, which appears to be the strike of the rocks. The dip is to the 

eastward at a high angle. While no accurate measurements could be 

made, the thickness of the formation is certainly not under 2,000 feet. 

The quartzite is white, compact, and brittle, with a uniform texture, and 

is traversed by thin iron seams. Near the base of the formation the 

qunrtzite is interstratified with beds of conglomerate, the pebbles being 

of quartz, and many of them having been pressed and elongated in the 

direction of the strata. The formation is cut by dikes of dark intrusive rocks which are probably diorites. At the head of the northern 

branches of French creek, conformably under a quartzite, is a series of 

thinly laminated dark argillaceous slates and schists, which dip eastBull. 86 18
274 PEE-CAMBEIAN ROCKS OF NORTH AMERICA. [BULL. 86.

ward into the mountain. Below these are quartzose argillites, which 

are again underlain by crystalline schists. Mill peak, north of east 

from Medicine peak, has at its base a white quartzite, which is overlain 

by a body of red conglomerate resembling the red jasper conglomerate 

of the Huronian series of lake Huron. Above this is amorphous 

quartzite, and the peak is capped by white and gray siliceous limestone. 

The prevailing dips at Mill peak are to the west, while those at Medicine peak are to the east, indicating that there is a broad synclinal fold 

between the two. A striking characteristic of the entire series is the 

banded and laminated appearance of the constituent minerals. The 

Archean series of the Medicine bow range present many marked features analogous to the Hurouian formation on the shores of hike Huron 

and Canada, as well, as to various localities throughout the Appalachian 

chain } and they are with considerable hesitation, however recognized 

as of Huronian age, because they are so Avidely separated from any 

beds distinctly recognized as such, and the reference is based entirely 

upon lithological evidence. The rocks also present many features in 

contrast with Laurentian rocks of the Colorado Front range.

The Park range, the third of the great Archean uplifts of the Rocky 

mountains, is a system of highly crystalline rocks of Archean age. The 

later rocks form a very subordinate part of the uplift, rising not more 

than a few hundred feet above the plain, Avhere they rest uuconforniably on the older series. The rocks of the Park range resemble more 

closely those of the Colorado Front range than they do the Medicine 

bow, and are referred to the Laurentiau. The range contains much structureless granite overlain by gneisses and schists similar to the series of 

the Colorado range, but carrying more hornblende-bearing beds in the 

upper members. On the other hand, there are not wanting rocks which 

are characteristic of the Medicine boAv series and which were referred 

to the Huronian formation. The range has a monoclinal structure with 

the prevailing dips to the west, while an outlying spur to the. east 

indicates the existence of the eastern side of the fold.

EMMONS,6 in 1877, describes Rawlings peak as an outlying area of 

Archean granite-gneiss which shows distinct lines of bedding, having 

an inclination of 45° to the west, while the overlying quartzites and 

sandstones dip 10° to the east.

KiNG,7 in 1878, describes the rocks which unconformably overlie the 

Archean of the Colorado range as varying from the lowest Paleozoic tip 

to the post-Pliocene. The Archean core of the range is a broad central 

anticline, the arch having a flat summit and the dip increasing rapidly 

as the axis becomes distant. In this range complex faulting, rnetamorphism and crystallization, combined with widespread erosion, took 

place before the beginning of Cambrian time. The rocks comprise 

granites and granite-gneisses, above which, with no apparent unconformity, are red granites showing distinct bedding, and above these a 

great thickness of mica-gneisses, the estimated thickness of which is
THE CORDILLERAS. 275

12,000 to 18,000 feet. From the lowest exposure to the highest there 

is a gradual passing from the structureless granite to the dark micagneisses. Among eruptive rocks are granites, gabbros, and fylsiteporphyries. The Clark's peak ridge is thought to be another and later 

series of rocks than those of the Colorado range.

In the Medicine bow range, above the hornblendic and dioritic, 

gneisses and schists are quartzitic schists, argillites, and limestones. 

The gneisses and hornblende-schist are older and underlie, in apparent 

conformity, the quartzites.

In the Park range the crystalline rocks all dip to the west, being bat 

lialf of an anticline, the other half having suffered a deep downthrow 

which has only left traces of the easterly dips. The rocks are granite, 

gneiss, hornblende-schists, and dioritoid rocks, \vith a limited quantity 

of quartzites, there being no eruptive rocks, unless some obscure dioritic bodies are intrusive. At Jacks creek is a bed of pure white 

quartzite 50 feet thick. The upper members of the Medicine bow and 

Park ranges, somewhat less than 12,000 or 14,000 feet thick, are referred 

to the Huronian and the remaining formations to the Laureutian.

ENDLICH," in 1879, describes KaAvlings peak as consisting of a metamorphic granite nucleus about which the sedimentary strata are qua 

quaversally arranged.

VAN HiSE,9 in 1889, made observations upon the Laramie and Medicine bow ranges.

The La-ramie hills at Sherman, where most structureless, are found 

to have alternate bauds of coarse and fine material. The latter are 

more resistant to weathering and stand out as ridges. This stratification or flowage or foliation structureisat a flat angle 15° or 20°. The 

country granite is cut by very numerous dikes of granite, which project above the ground in intersecting ridges.

The course of travel in the Medicine bow range was up one of the 

branches of the Laramie river to Medicine peak, and over this range in. 

a course north of west across the strike of the rocks down Brush 

creek. Mill peak was visited.

The pre-Cambrian rocks first found are banded and contorted gneisses, 

varying from fine grained to granitoid varieties, which are cut by 

hornblendic and granitic veins or dikes, with here and there considerable areas of massive granite. In passing toward the interior of the 

range the granite becomes less plentiful and the gneiss more laminated, 

passing into regularly banded gneiss, which appears to grade by imperceptible stages, into fine grained green schist, and finally into black 

slate. In continuing to pass from east to Avest quartzites are found, 

then abroad belt of yellowish, white, finely granular chert, with layers 

of cherty limestone sometimes ferruginous. About a mile before Medicine peak is reached the quartzites appear. These continue (often conglomeratic) to beyond Medicine peak. West of Medicine peak are 

again found slates, slate-conglomerates carrying abundant pebbles
276 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 88.

of white quartz and granites and inter stratified with quartzite. Schistose and massive basic rocks, much altered, in dike-like forms, are 

found in the clastic series precisely as in the gneissic series. They 

oftentimes strike approximately parallel to the inclosing rocks. East 

of Medicine peak the rocks, including the gneissoid and clastic series, 

have a dip of about CO0 to 80° to the southeast. Therefore the Medicine peak series appears to underlie the gneissoid series. The dip of 

the Medicine peak series in going north of west beyond the mountain 

becomes flatter, until 2 or 3 miles beyond the crest the dips are not 

higher than 30°, which observations agree with Hague's statement that 

west of Medicine peak is the crown of an anticline. As the strike of 

the Medicine peak series is nearly toward Mill peak, and as on the 

top of that peak there are cherts (Hague's amorphous quartzite) and 

cherty limestones very like those found east of Medicine peak, it seems 

probable that the Mill peak series represents these cherty limestones. 

Though the original sedimentary character of the Medicine and Mill 

peak series is evident, the pressure to which the rocks have been subjected is so great in places that the slate-conglomerates bearing granite 

pebbles take on an appearance closely resembling gneisses. The grains 

of quartz in the fragmental quartzites in thin section also show profound evidence of dynamic action. However, as the layers of pebbles 

in the quartzites and the fine laminations in the cherts and cherty 

limestones correspond with the schistose structure, there can be no 

doubt that the strikes and dips are those of bedding.

The foregoing facts seem to imply that in passing up from the gneissic series to west of Medicine peak we have passed a syncline overturned to the west, and 2 or 3 miles west of Medicine peak have nearly 

reached the crown of the next anticline. This structure makes tlie 

slates and slate-conglomerates bearing granite pebbles the base of the 

clastic series, above which are the quartzites, and occupying the highest position in the center of the syncline are the cherts and cherty limestones of Mill peak and those east of Medicine peak. The elastics thus 

rest upon the granite-gneiss series. No contacts or evidence of discordance in strike or dip were found between them,, but the conglomerates 

bearing granitic detritus show the presence of a granite earlier than 

the formation of these beds, and presumably the present apparent accordance and transition are due to dynamic action, combined, perhaps, 

with the disintegration of the earlier series before the elastics were deposited.

SUMMARY OF KESULTS.

It is plain that in the Medicine bow range are two classes of rocks: 

those which are thoroughly crystalline and are mostly of the acid 

type, and those which are unmistakable elastics, such as quartzites, 

conglomerates, marbles, cherts, etc., while in the Laramie and Park 

ranges is only the first class, if the white quartzite, which seems to be 

in the nature of a vein in the latter, is excluded. The granites and
VANHISE.I THE CORDILLERAS. 277

gneisses wore regarded by Haydcn as eruptive, and they were believed 

to have intruded and metamorphosed the overlying Paleozoic limestones. King and Hague, on the other hand, regard all of the material of the three ranges as metamorphic, with the exception of the basic 

dikes and possibly some small areas and dikes of a later granite. That 

the horizontal sedimentary rocks were deposited uuconformably upon 

and against these ranges is now admitted by all; so that the truth of 

the observations of Hayden must be considered doubtful, unless he 

found some place where there is actually present later important masses 

of intrusive granite.

At the present time many would doubt the conclusions of King and 

.Hague, tliat because the structureless granite of the center' of the 

ridges vary gradually in. passing outward into well laminated gneisses 

and schists, therefore the whole is of sedimentary origin, the interior parts being more completely metamorphosed than the exteriors. 

These relations might equally well be produced by the increasing effects of dynamic action, upon the outer borders of once massive ranges. 

The variation of massive or nearly massive core rocks into laminated 

gneisses and crystalline schists on the outer borders, which occur in 

many other mountain regions, are thus explained by numerous later 

observers, the whole being regarded as igneous. The lamination is 

explained equally as well by one theory as by the other; for in either case 

the central axes are the parts which are most deeply buried, and which, 

even if composed of material originally sedimentary, have become recrystallized. On either hypothesis it is probable that in the region 

under discussion are two fundamentally different series, the very ancient crystallines and the pre-Cambrian elastics. The presence of 

abundant granite debris in the lower members of the Medicine peak 

series certainly shows the existence of a granite earlier than this time. 

That the elastics are later than the ciystallines is perhaps further indicated by the numerous dikes of granite which are found in the main 

granite area, but have not been noted as cutting the elastics. It can 

not be said whether many of the mica-schists and other intermediate 

kinds of rocks such as occur in the Medicine bow and Park ranges 

belong with the Archean or the Algonkian. It is wholly a,mong the 

possibilities that schist series exist which are older than the granite; 

these together forming a basement complex upon which the readily 

recognizable elastics were deposited.

SECTION II. CENTRAL AND WESTERN WYOMING. 

LITERATURE OF THE BIG HORN MOUNTAINS.

HAYDEN, 10 in 1801, states that red feldspathic granites, with metamorphic slates and schists, constitute the nucleus of the Big Horn 

mountains. As these are surrounded bv strata as recent as the Cretaceous, this uplift is subsequent to this time.
278 PRE-CAMBRIAN BOOKS OF NORTH AMERICA. [BULL.86.

HAYDEN,H in 1868, states that the unconformity between the, crystalline and un metamorphosed strata at the Big Horn mountains is 

very apparent.

CAKPENTER, 12 in 1878, describes the Big Horn range as composed at 

the base of thick masses of Primordial sandstone resembling the Potsdam sandstone of the Black hills, although the heat coeval with the 

upheaval of the mountains has probably obliterated the fossils which 

are so abundant in that region. The sandstone rests unconformably 

against the Archean, is inclined from the flanks, is folded, and in many 

places is upturned as in the Black hills and Colorado mountains. Above 

the sandstone is a limestone containing numerous casts of Spirifer cameratiis. The crystalline rocks appear at an elevation of about 9,000 

feet and compose the higher parts of the range. Near the summit 

fine grained, grayish granite predominates, occasionally varied by 

various patches of mica-schist. The Owl creek mountains are composed of porphyritic granite rich in feldspar, which give place at higher 

elevations to a gneissoid granite. They connect the southern end of 

the Big Horn mountains with the northern part of the Wind river 

range.

LITERATURE OF THE RATTLESNAKE MOUNTAINS.

BNGELMANN,5 in 1876,|states that granites and granitic syenites which 

are regarded as igneous rocks form, a large part of the Kattlesuake 

mountains.

LITERATURE OF THE SWEETWATER AND ADJACENT MOUNTAINS.

BALL,,13 in 1835, notes granitic rocks along the Sweetwater.

HATDEN, 11 in 1868, mentions granites and syenites as occurring in 

the Sweetwater mountains.

BNGELMANN,5 in 1876, places the crystalline schists between the three 

crossings of the Sweetwater and South pass, and those on the eastern 

slope of South pass as metamorphics. They include gneiss, mica-schist, 

argillaceous and siliceous schist, and hornbleudic rocks.

BNDLICH, 8 in 1879, describes in the Sweetwater valley and in adjacent regions Prozoic and rnetamorphic rocks. In the Sweetwater 

hills are Prozoic rocks, coarse grained, structureless granite, like those 

west of the Wind river mountains which are cut by basaltic dikes, but 

which never penetrate the overlying younger rocks. The metamorphic 

granite of the Sweetwater and Semiuole hills is regarded as a continuation of the youngest granite of the eastern slope of the Wind 

river range. East of Elkhorn gap is found a series of folded sedimentary beds, upon both sides of which is granite apparently of the sa.me 

character. The northern and northwestern portions of the granite 

hills, instead of being composed of Prozoic granite, are formed of stratified granites with hornblende-schists. Toward the eastern termination 

the stratification is so apparent that from a short distance the rocks
THE COKDTLLERAS. 279

were supposed to be unchanged sedimentary ones, and the suspicion 

presented itself that a portion of these are metamorphosed Silurian 

beds. The Potsdam quartzite with an easterly dip is found to rest 

upon the schists, and at the western end of the Sweetwater hills subCarboniferous dolomites rest directly upon the Prozoic granites. In 

the Sweetwater region the younger metainorphics occupy a more conspicuous position than the older metalliferous schists. That the older 

schists and Prozoic granites do not appear is due to the thickness of 

the youngest" metamorphic series, erosion not having succeeded in cutting through them. The metainorphics are all referred to the Huronian system.

LITERATURE OF THE WIND RIVER MOUNTAINS.

HATDEN, 10 in 18C1, states that the Wind river mountains have a 

nucleus of red and gray feldspathic granite.

HAYDEN, 11 in 1808, states that the stratified rocks rest unconformably upon the granites and syenites of the Wind river mountains along 

the eastern slope.

HAYDEN,4 in 1872, describes the Wind river range as forming a complete anticline. It has a nucleus of granitic or gneissic rocks rising on. 

either side step by step toward the central axis, and on each side of 

the nucleus are the various unchanged rocks inclining at a variety of 

angles. From fort Stambaugh northwest toward the granites of Wind 

river is found for'a distance of 10 miles metamorphic slates.

COMSTOCK, 14 in 1875, describes the Wind river mountains as having 

a nucleal area of gray and reddish granites, gneissoid granites, gneisses, 

metamorphic slates and schists, and pre-Potsdam metainorphics, this 

.being the order of succession from the center to either flank. It is 

doubtful whether any igneous rocks here occur, and there appears to 

be a gradation from the structureless granites to the pre-Potsdam metainorphics.

ENDLTCn, 8 in 1879, describes the geology of the Wind river mountains and country eastward. The crystalline rocks are divided into 

Prozoic and Metamorphic. Placed as belonging to the Prozoic is the 

.coarsegrained, structureless red granite forming the subsidiary range 

along the western base of the mountains. Going eastward the granites 

disappear and in the Wind river range schists take their place. These 

granites and those of the Sweetwater and Granite hills are believed to 

have a subterranean connection and are regarded as the oldest rocks of 

the Wind river mountains because of the absence of all structure, their 

position relative to the range and their relations to the undoubted inetamorphics to the east. Against them were deposited the old metalliferous schists. Granite composing the main chain followed, and this was 

succeeded by a narrow band of schist, and the fourth or lowest group 

is represented by the younger granites. The metamorphic rocks of the 

Wind river mountains are mainly granites but are associated with 

schists; but the layers of different miueralogical constitution do not
280 PKE-CAMBRIAN KOCKS OF NORTH AMERICA. [BULL. 86.

appear to remain constant in certain zones. Passing to the eastward 

the granites disappear and are replaced by schistose granites or typical 

schists. The granites are flexed and contorted in every possible direction and contain simple bauds of micaceous and chloritic schists, which 

denote the original planes of stratification. It is believed that by a 

careful examination evidence will be found bearing upon the former 

condition of this metamorphic area. The Wind river range is regarded 

as a steep anticlinal fold. The rocks constituting it are regarded as 

representing siliceous shales (schists) and are more or less argillaceous 

sandstones (granites). On the eastern side of the Wind river range is 

found hard red quartzitic sandstones directly overlying the youngest 

metamorphic granites. It extends up the gently sloping ridges in a 

scalloped line. In direct contact with the granites it is difficult to 

determine where the granite ends and the quartzite begins, so that it 

may be said that the quartzites and granites blend into each other. It 

appears that the lowest Silurian strata were deposited before the thorough metamorphosis of the entire mass took place, unless the change 

in the sandstone is caused by a generation of heat during the period of 

mountain elevation. The Archean rocks of the Wind river, Sweetwater, 

and adjacent ranges are classified into the Huronian, Laurentian, and 

Prozoic systems. The first includes micaceous, hornblendic, and chloritic granite, 30,000 feet thick. The Laurentian includes metalliferous 

schists composed of quartz, feldspar, hornblende, and mica, 18,000 feet 

thick. The Prozoic includes massive structureless muscovite granite 

of indefinite thickness.

PEALE,15 in 1879, states that the western foothills of the Wind river 

mountains and a few isolated buttes are composed of muscovite granite, 

the most prominent of the latter being Fremontfs butte.

ST. JOHN, 16 in 1883, describes the Archean rocks of the Wind river 

range and gives a number of sections showing the unconforn'iable relations of these rocks to the overlying Potsdam and higher sedimentaries. The Archean area is composed of granitic, gneissic, and various 

schistose rocks, including horubleudic, micaceous, talcose, and garnetiferous varieties.

LITERATURE OF THE GROS VENTRE AND WYOMING RANGES.

ST. JOHN, 17 in 1879, states that the G-ros Ventre range has an 

Archean nucleus, consisting chiefly of distorted gneissic and schistose 

layers, and forms a sort of transverse bar or truss connecting the 

Wind river and Teton ranges. The Primordial quartzite was seen 

lying in immediate contact unconformably above the Archean schists, 

from which it is separated by a rose-colored finely laminated gneissoid 

layer, which maybe the metamorphosed basal member of the quartzite.

ST. JOHN, 16 in 1883, further describes the Gros Yentre range and 

gives various sections-through it. The Primordial quartzite rests directly upon the Archean rocks. In the Wyoming, as in the Gros Ventre 

range, the Archean is unconformably below the stratified rocks.
VAN RISK.] THE CORDILLERAS. 281

LITERATURE OF THE TETON RANGE.

BRADLEY, 18 in 1873, describes othe central nucleus of the Teton 

mountains as consisting of granites, gneisses, and schists which vary 

greatly in character. No rock succession was ascertained. The granite 

is in thick solid beds and the other rocks are much broken and tilted 

in various ways, and are crossed in every direction by innumerable 

large and small veins, mostly of quartz, but a few of granite. There 

is a general strike in an east and west direction. Trap-like rocks are 

interlamiuated with the gneiss and granite, which suggest that they 

may be dikes, but they are evidently conformable with the layers and 

were either contemporaneous sheets or else subsequent intrusives.

ST. JOHN, 17 in 1879, describes Archean rocks as constituting the nucleal ridge of the Teton mountains. The major portion of them are 

metamorphics of a gneissic or schistose variety. The Archean strata 

of the Teton, Wyoming and Gros Ventre ranges are divided into 

Huronian and Laurentian. With the former are placed the quartettes, 

micaceous and chloritic slates forming heavy deposits several thousand 

feet in thickness and developed only in the southwest, while with the 

Laurentian are the gneisses, various schistose rocks, and granite. In 

the southwest part of the Teton district is a narrow tongue of quartzites which are placed with the Primordial, but may be Huronian.

SUMMARY OF RESULTS.

The rocks referred to the Archean by the various authors can, with 

consider able certainty, be considered pre-Cambriaii, as the region is one 

in which no folding has taken place since the beginning of Paleozoic 

time, and the various members of the Paleozoic are found in unconformable contact with the underlying, crystallines at many points. ' It 

is not necessary to assume, as was done by Endlich, that a portion of 

the metamorphisin of the Archean took place subsequent to Paleozoic 

time, for the indurated quartzites so often found in direct contact with 

the crystalline strata have probably been thus hardened by the now 

well known process of cementation.' The quartzites which so closely 

resemble the unaltered granite are doubtless recomposed rocks which 

have been cemented in the same manner.

Whether among the pre-Cambrian rocks in these various ranges of 

mountains there are any which are now of a distinctly clastic character is 

uncertain. Those between fort Stambangh and the central Wind river 

mass spoken of as metamorphic slates, and the rocks described by St. 

John in the southwestern part of the Teton district as consisting of 

quartzites, micaceous and chloritic slates, may very likely be of this 

character, but it is not certain that the latter do not belong to the Cambrian, for nothing is said of their relations to the recognizable Paleozoics.

The separation of the rocks into Laurentian and Huronian, or into 

Prozoic, Laurentian and Huronian, as is done by Endlich, is purely litliological. They are all thoroughly crystalline, and have been assumed by
282 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. fBmx.80.

the. various authors to be metamorpliic because having a lamination or 

foliation, and the more massive rocks are regarded as being older because 

more metamorpliic, and also because they are usually core rocks. As 

has been seen in the case of the Laramie hills and other regions, these 

facts may be equally well explained by regarding the rocks as all ancient igneous rocks, parts of which have been given a laminated structure by dynamic action.

Nowhere is anything said as to any tin con form able relations between 

any parts of the various series referred respectively to the Huronian, 

Laurentian, or Prozoic, as the case may be. Consequently the only sure 

structural conclusion reached is that there is in these mountain ranges 

a great complex of granites, gneisses, and schists, thoroughly crystalline, and as yet undivided, which are of pre-Cambrian age.

SECTION III. CENTRAL AND SOUTHWESTERN MONTANA, WITH ADJACENT PARTS OF WYOMING AND IDAHO.

LITERATURE.

HAYDEN,10 in 1861, describes along the Madison, one of the- forks of 

the Missouri, beds of feldspathic rocks, and mica-slates an delay-slates 

above the eruptive granites of the region.

HAYDEN,19 in 1872, describes Archeaii rocks at many points in southwestern Montana. Among the localities mentioned, the following are 

worthy of note: Upon Black-Tailed Deer creek in southwestern Montana is an immense thickness of alternating beds of quartzites, true 

gneiss and mica-schist, the first predominating, and inclining to the 

west from 30° to 45°. Old granite ridges are also found. ° On the north 

side of this creek are gueissic beds, which incline to the northwest at 

angles varying from 30° to 60°. On the Stinking water are immense 

thicknesses of micaceous gneiss underlying massive layers of quartzjte. Along the Madison canyon is found granite. The rocks adjacent 

to Virginia City are clearly stratified, wholly metamorphic, and are 

regarded as below the Paleozoic. Upon the Upper Gallatin are granitic nuclei, with the unchanged sedimentary beds upon the sides and 

summits inclining at various angles. In the first canyon of the Yellowstone is true gneissoid granite and micaceous gneiss of different 

shades of color, giving its sides a peculiarly stratified appearance. At 

Cinnabar mountain is a plainly metamorphic reddish feldspathic quartzite, upon which rests un conform ably the Carboniferous limestone. 

Hell-Koaring mountain consists of stratified gneiss and massive red or 

gray feldspathjc granite. At Horse plain valley are quartzites and 

micaceous schists, which rise beneath the limestones and quartzites of 

Carboniferous age.

PEALE,20 in 1872, gives many details with reference to the lithological 

and mineralogical character of the rocks, the locations of which are 

given by Hayden.
VAKtnsE.] THE CORDTLLEKAS. '283

llAYJJEN,21 in 1<S7-'), gives many additional facts with reference-to the 

occurrence of Archean rocks in southwestern Montana and adjacent 

regions. The mountain range east of the Yellowstone, supposed to be 

mostly of igneous origin, has the characteristic granitic nucleus common to the mountain ranges of the region. In ascending the lower 

canyon of the Yellowstone the first ridge is composed mostly of metamorphic quartzite, the second of mica-schists and granitoid gneiss. The 

ribboning and banding of the gneiss is quite remarkable for its perfection and regularity. Granitic rocks constitute the nucleus of the Yellowstone range and make up a rugged granite range east of Clarks 

fork. At Henrys lake and .Tahgee pass the quartzites and gneissic 

rocks appea.r beneath the limestones. The lower portion of the unchanged rocks are pebbly arenaceous sandstones and limestones containing pebbles which are much worn and are either quartz or micaceous 

gneiss, showing that the sediments were derived directly from the 

metamorphic rocks. The lowest strata of unchanged rocks are here 

regarded as Silurian, and probably Potsdam, although no organic 

remains were found. The Carboniferous limestones higher up are filled 

0 with characteristic fossils. In the Middle canyon of the Madison the 

stratified rocks are also believed to belong to the Potsdam epoch, 

although no fossils were found lower than the Carboniferous, and here 

the unconformable relations of the limestones to the metamorphic rocks 

are clearly shown. On both sides of the Madison there is, in restricted 

localities, an enormous development of very hard gray quartzitic sandstone, apparently partially metamorphosed, which evidently forms the 

underlying rocks of the sedimentary strata resting on the strictly metamorphic gneiss. No organic} life has been found, yet it undoubtedly 

belongs to the oldest Silurian. Along the valley of the Madison, below the mouth of Cherry creek, for several miles there are successions 

of gneissic beds thousands of feet in thickness, which show great variety of composition and flexures in the bedding. In this gneiss are 

layers of black hornblende gneiss 4 to 6 feet thick, which appear as 

though they were intrusions of trap. Near Helena the sedimentary 

beds overlying the granite are tilted from 20° to 45° past a vertical. 

The work of reducing the metamorphic strata which underlie the entire 

country to a system and connecting them over extended areas has not 

been attempted, and it seems to the author an almost hopeless as well 

as a fruitless task.

PEALE,22 in 1873, describes at many localities crystalline rocks in 

southwestern Montana "and adjacent regions. Gneissic and granitic 

rocks are mentioned in the Cinnabar mountains, in the rocks of the 

Third canyon of the Yellowstone, at Elk creek, at the junction of the 

two forks of the Yellowstone, at West Gallatin canyon, Bozeman 

creek, and other localities. Upon one of the head waters of the Madison 

are found quartz-schists and chlorite-schists, below which in apparent 

conformity are layers of limestone. Still below these are Carboniferous
284 PRE-CAMBRTAN ROCKS OF NORTH AMERICA. [BULL. 86.

limestones. The whole is believed to be an overturn. Between Rod 

Rock lake and Henry lake is an exposure of quartz-schist dipping1 to 

the southwest at an angle of 20°, estimated to be 2,000 feet in thickness, which is believed to rest directly upon the granite. On Cherry 

creek the gueissic rocks are succeeded by beds of massive quartzite, 

shale, limestones, etc., resting unconformably upon them, the latter 

being probably Lower Silurian.

HAYDEN,23 in 1876, describes some geological sections about the 

headwaters of the Missouri and Yellows tone rivers. There is an anticlinal axis between the Madison and Jefferson which has a granitic 

nucleus, and on the east side of the Gallatin the Silurian rocks rest 

upon granitic hills.

' HOLMES,24 in 1883, describes the Silurian strata as resting upon the 

metamorphic rocks at Cinnabar mountains. The butte at Bear gulch 

is composed of vertical shales, and these are underlain by'metamorphic 

quartzites. Between the butte and Junction valley are hard metamorphic quartzites and quartzitic schists which not improbably 

consist chiefly of altered and distorted Paleozoic or Mesozoic strata, 

but there is but slight resemblance to these formations. The ridge 

near the canyon of Bear creek is composed of schists that have a 

decided quartzitic character. The East Gallatin range is largely of 

granite. At different places the Archean granites are uucon form ably 

overlain by the Silurian.

DAVIS,25 in 1886, describes Archean rocks as occurring in the neighborhood of JSTeihart, about the headwaters of Belt creek in the Little 

Belt mountains. They are dark reddish and gray gneisses with the 

folia generally at steep angles, cut by granitic eruptions that were not 

found to extend into the overlying bedded rocks. The Paleozoic series 

begins with a vast series of Lower Cambrian barren slates, at least 10,000 

or 15,000 feet thick at many places. The slates are capped by hard sandstone or quartzite, 100 or 150 feet thick, persistent throughout the area 

examined, which is overlain by an equally persistent trilobitic limestone 100 to 300 feet thick clearly of Potsdam date. With the upper 

members of these slates are found diabasic eruptions. These lower 

Cambrian slates are found in the main range at Cadottes pass, in the 

Big Belt mountains, and in the Little Belt range. In the sections the 

Archean rocks at Little belt are represented as resting unconformably 

beloAv the Lower Cambrian slates, while on the Bridger range they are 

placed in conformity with the slates.

PEALE,20 since 1884, has been working on the "Three Forks Sheet" 

of Montana (the square degree included between 111° and 112° of longitude and 45° and 46° of latitude). In the northern part, in the 

Bridger range, of this area is found Archean gneisses.

Other Archean areas are the one extending north of Virginia city 

some 28 miles, in which a body of eruptive granite occurs, and the one 

bordering the canyon of the Madison. The gneiss of the Madison can-
VAN mat.] THE CORDILLERAS. 285

yon extends across to the Gallatin canyon, a distance of 24 miles. This 

latter belt is about 12 miles in width. There are also two smaller 

gneissic areas bordering the southern edge of the Gallatin valley. The 

beds of Lower Cambrian age at a number of localities in the range include 

angular fragments and masses of gray and red gneiss, evidently derived 

from these Archean beds.

In the vicinity of the Three forks and in the northern portion of the 

Bridger range, lying -between the basal quartziteof Lower Cambrian 

age and the Archean gneisses referred to above, is another series of beds 

that are considered pre-Cambrian. This group, referred to the Algonkian, has a thickness of 5,000 or 6,000 feet in the Bridger range and is 

correlated with the Lower Cambrian barren slates of much, greater 

thickness found by Davis farther to the north. The beds are made up 

of alternations of coarse micaceous sandstones and fine conglomerates 

with beds of hard argillaceous slates and bands of very hard thinbedded dark blue limestones. These are the beds seen by Hayden in 

1861 which were mistaken for eruptives, and which were described by 

Teale in 1873. Where the lowest exposures were noted, pebbles and 

angular masses of the Archean gneisses are numerous in these sandstones, indicating that Archean land masses existed not far to the southAvard. In fact the ancient shore line crossed the area from 12 to 15 

miles south of the northern limit of the Three forks sheet. As to age, 

this series is probably pre-Cambrian as it lies below beds containing 

Lower Cambrian fossils, being nonfossiliferous themselves so far as 

examined. So far as observed no evident unconformity exists between 

the series and the overlying Cambrian beds, but there is certainly an 

unconformity by subsidence, for after the series was deposited there 

was an orographic movement by which the Archean area of nearly the 

entire district of the sheet-south of the Three forks was submerged just 

prior to the beginning of the Cambrian, as is shown by the great southward extent of the lower or basal quartzite over this area which was 

not before submerged and which therefore shows no rocks of this Algonkian series. Whether the movement occurred immediately after the laying down of the Algonkian beds just described or after an interval can 

not be decided with the meager data now at hand.

South of the old shore line the Algonkian group is absent, the lower 

quartzite of the undoubted Cambrian everywhere lying unconformably 

upon the Archean gneisses, with the exception of two localities, where 

it rests upon a series of beds considered to be a lower division of the 

Algonkian. The main area is on the west side of the Madison river, 

about 20 miles south of Meadow creek, and is about 8 miles in length 

by about 4 in width. A limited area of these beds occur on the east 

side of the Madison valley at the west edge of the Madison range, between Bear and Indian creeks. The series consists of crystalline limestones, mica-schists, quartzites, and gneisses, very highly inclined and 

conformable so far as seen with the stratification, or bedding of the
286 PRE-CAMBRIAN EOCKS OP NORTH AMERICA. [BULL. 86.

gneisses. Without more detailed examination and search for obscure 

folds it is impossible to estimate the total thickness, but it is certainly 

very great.

SUMMARY OF RESULTS.

It is evident from the literature, as well as from Hayden's own statement, that no systematic work has been done among the pre-Cambrian 

rocks, with the exception of that by Peale on the Three forks sheet. 

The information, at hand makes it clear that this region will yield results of extreme interest when considerable areas are mapped. In the 

region are great areas of intricately mingled granitic and gueissic rocks 

which certainly belong to the Archean. Associated with this class of 

rocks are immense thicknesses of regularly bedded gneisses, micaschists, chlorite-schists, quartz-schists, quartzites, and limestones. 

Whether the regular lamination of the gneiss is due to sedimentation 

or to other forces is uncertain, but the great belts of interstratified 

crystalline limestone, quartz-schists, and quartzites are evidence that 

here is a series of clastic origin, although at the present time it has 

become thoroughly crystalline. The relations of this series to the 

granites and gneisses doubtfully referred to the Archean have not been 

worked out.

There is also in this region, as shown by the work of Davis and 

Peale, a great series of unaltered strata which are probably Algonkian. 

This series is a downward succession of barren slates below the fossiliferons Cambrian, and if Algonkian, is the uppermost division and 

equivalent to the upper Algonkian of the Wasatch. Peale's results 

indicate that while there is no actual unconformity, there is u change 

of physical-conditions, a subsidence, and perhaps a real time break between the Cambrian and Algonkian. Nowhere yet have the unaltered 

barren slates and the more crystalline series of clastic origin been found 

in contact. Between the slates and the Archean gneisses is a great unconformity, and there is little doubt, when the unaltered series is carried over to the vertical limestones, qnartzites, and quartz-schists, that 

it will be found to rest upon them un con form ably. There is, then, in 

this region probably two series of Algonkian rocks, one almost completely unaltered, the other thoroughly crystalline, and both of great 

thickness.

SECTION IV. UTAH AND SOUTHEASTERN NEVADA. 

LITERATURE OF THE UINTA MOUNTAINS. '

MARSH,27 in. 1871, states that in the Uinta mountains is an extensive 

series consisting of reddish sandstones and quartzites, sometimes metamorphosed and apparently without fossils. The series is referred provisionally to the Silurian on the ground that resting conformably upon 

them arc limestones bearing Carboniferous fossils.
U.S.GEOLOGICAL SURVEY. 

42r 120

119 no 

UNCLASSIFIED PRE-CAMB. ALGONKIAN ALGONKIAN ? POST-ALGONKIAN Gr

GEOLOGICAL MAP OF UTAH AND NEVADA

SHOWING PRE-CAMBRIAN ROCKS

Compiled from the Powell,Kin.g and Wheeler Reports

Seals 4.W<5<>6.
VANHISE.] THE CORDILLERAS. 287

HAYDEN,4 in 1872, states that in the Uintas, from the red beds of the 

Triassic to the oldest quartzites no unconformity was detected. The 

whole series has a thickness of 10,000 feet or more; of this the lower 

8,000 consists of sandstones and quartzites. Although no fossils Avere 

found, the upper part of these 8,000 feet is believed to be .Silurian and 

to pass down without a break to the rocks of the Huronian age. The 

quartzites are like the Sioux falls, Dakota, quartzites which are associated with the pipestone referred by Hall to the Huronian. In the 

Uinta series is an excellent illustration, of a gradual transition from 

unchanged to metamorphic rocks.

Passing upward to the crest of the mountains, but downward in a 

geological sense, we find a series of purplish sandstones and slates, 

conformable with the limestones and apparently unchanged, which 

gradually pass into thick beds of gray and purple quartzite, which are 

exceedingly brittle and plainly metamorphosed by heat. The later 

formations once passed over the older ones in the Uintas, and therefore 

there has been in this region tremendous erosive forces. On lied creek, 

the only place where such a rock is found, is the largest display of white 

quartz that the author has seen in the West. This is associated with 

outbursts of old trap and some beds of true gneiss and mica-schist. 

The igneous matter has protruded itself in every opening or fissure in 

every possible direction, sometimes between the strata and sometimes 

across them, in thin layers or in huge branching1 masses. It is believed 

that this igneous material was protruded among the quartz beds prior 

to their upheaval. It is difficult to account for this development of quartz 

with gneiss, which rises abruptly above the quartzite, occupying a belt 

5 to 9 miles in width and ending as abruptly as it commences. Tlie 

upper quartz ites an d white quartz beds seem to conform. It i s rein ark ed 

that the geology of the eastern portion of the Uinta range is very complicated and interesting, but to have solved the problem to entire satisfaction would have required a week or two.

PoWELL,28 in 1874, describes in the Uinta mountains crystalline 

schists upon which rest unconformable Carboniferous rocks.

POWELL,29 in 1876, describes the Uinta sandstones, shales, and quartzites 12,500 feet thick, as resting unconformably below the Lodore 

group. Again, un conformably below the Uinta sandstone is the Red 

creek quartzite associated with hornblendic and micaceous schists, 

10,000. feet thick. It is evident that the metamorphisrn of the Ked 

creek quartzite is anterior to the deposition of the Uinta group, for the 

beds of the latter, especially near the junction, are chiefly made up of 

fragments of the former; hence the unconformity is very great, and the 

quartzite Avas a lofty headland in the old Uinta sea perhaps 20,000 feet 

high when the lowest member of the Uinta sandstone was formed. 

The period of erosion separating the Uinta sandstones from .the Carboniferous beds was sufficient to carry away a,t least 3,000 feet of the 

former, and how much more can not be said. This unconformity is
288 PRE-CAMJ3RIAN ROCKS OF NORTH AMERICA. [BULL.88.

seen at Whirlpool canyon and the canyon of Lodore, the difference 

of dip between the two groups being from 4° to 6°, and the in embers 

of the Lodore group steadily overlapping the upper members of the 

Uinta and cutting off more than 2,000 feet of the latter. At the canyon 

of Lodore the TJinta sandstone also protrudes into the Lodore shales. 

On the northeast side of O-wi-yu-kuts plateau the Uinta sandstones 

are seen to disappear, having been cut off by erosion before the deposition of the limestone, and there is from 1,000 to 2,000 feet more of the 

Uinta sandstone at one end of the ridge than at the other. The unconformity can also be seen in the canyon of Junction mountain, and 

lias been observed on the south side of the Uinta mountains in a canyon cut by the tributaries of the Uinta river. It is suggested that the 

Uinta sandstones may be considered as Devonian, an opinion which 

would be yielded upon the slightest paleoutological evidence to the 

contrary.

The Bed creek quartzite is believed to be Eozoic. This Eozoic is 

in large part a pure white quartz, but is intimately associated with 

irregular aggregations of hornblendic and micaceous schists. These 

schists were, perhaps, argillaceous strata between the thicker strata of 

pure siliceous sandstone. The whole group has been greatly metamorphosed so as almost to obliterate the original granular or sedimentary 

structure so far as is apparent to the naked eye. Besides the recrystallization, they have been profoundly plicated or implicated, so that it 

is only in a general way that any original stratification can be observed.

The gi'eat mass of the Uinta range is of the Uinta sandstone. Intercalated with these are shales, argillaceous material, and semicrystalline quartzite; the whole group is exceedingly ferruginous and contains seams of clay ironstone. While weeks and months were spent 

in the search, no fossils were found in the Uinta group. The Uinta 

mountains as a whole have been produced by the degradation of a 

great upheaved block, having its axis in a general east and west direction. The upheaval is partly a flexed, partly a faulted one, the major 

part of the faulting and the steeper inclinations being on the north 

side.

EMMONS (S. E.),6 in 1877, describes the Uinta mountains as a remarkably simple and regular uplift of an immense thickness of conformable 

strata, the regularity being disturbed only about a small area of Archean rocks at the eastern end. These old rocks, occurring along Eed 

creek and covering a comparatively small area, are quartzites, white 

mica-s.ehists, and hornblende-schists, with a local development of paragonite beds, and they correspond most nearly to those classed as 

Iluronian in the Eocky mountains. The beds are steeply inclined and 

have suffered intense compression and distortion. The general section 

is that of a double anticline.

On these older rocks are seen the conformably gently dipping Weber 

quartziteSj and the succeeding beds were then deposited around the
VANHISE.] THE COKDILLEEAS. ' 289

shores of an Archean island. Above the Archean is a thickness of 

10,000 or 12,000 feet of unconformable beds, part of which consists very 

largely of quartzite and is regarded as before the Carboniferous, while 

the upper part is placed in the Upper Coal Measures and Permo-Carboniferous. The Upper Coal Measures are limestones and sandstones 

and bear fossils; but in the great thickness of lower beds referred to 

the Weber no fossils are found.

KiNG-,7 in 1878, describes the Archean rocks of the Uinta range as a 

group of pure white quartzites, hornblende schists, hydromica- (paragonite) schist, richly charged with garnet, staurolite, and minute crystals of cyanite. They are referred to the Euronian.

The Paleozoic rocks of the Uintas rest unconformably upon the 

Archean. They comprise an immense body of quartzites and indurated sandstones intercalated with shales, 12,000 feet in thickness, referred not, however, without some questioning to the Weber quartzite or Middle Coal-measures. Directly overlying these is a series of 

sandstones and limestones having a thickness of 2,000 or 2,500 feet in 

which Coal-measure fossils are obtained.

PEALE, 15 in 1879, describes in the Green river district, at Station 77, 

a Cambrian section consisting largely of quartzite and amounting to 

7,000 feet. At Station 130 is another red quartzite which has a limestone below it, and below them a series of green chloritic rocks unlike 

those of any other section in the district. The author inclines to place 

these below the Cambrian quartzites and considers them of probably 

Huronian age. None of these sections expose the underlying crystalline schists.

VAN HiSE,9 in 1889, examined the Archean core of the Uintas. The 

so-called white quartzite is found to be largely composed of white feldspar. It is thoroughly crystalline and its lithological affinities are rather 

with the granites than the quartzites. The black bands contained in 

it, supposed by some to represent original layers of a different constitution, and by others to represent dikes, were found to be much altered 

eruptives. The unconformable contact between the Uinta series and 

the Archean was seen at many points.

LITERATURE OF THE WASATCH MOUNTAINS.

HAYDEN, 19 in 1872, describes in the Wasatch mountains and on the 

canyon of the Weber a nucleus of granite. In Box Elder canyon are 

gneisses, quartzites, and slates. In the Port Neuf canyon there are 

exposed at least 10,000 feet of quartzite, the age of which is obscure, 

the only thing indicating its position being that Carboniferous fossils 

are found in the upper horizon.

SiLLiMAN,30 in 1872, regards the granite of Big and Little Cottonwood canyons as probably metamorphic from conglomerates, because 

of the conspicuous patches of dark colored material which they have 

iu a light gray matrix, and because with a glass there can be detected 

a sort of pebble-like rouiidness in the quartz of the granite. 

Bull. 86 19
290 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

HAYDEN,21 in 1873, describes syenite in the Little Cottonwood canyon 

of the1 Wasatch at the base of the series, upon which rest feldspathic 

gneissic strata, and unconformably upon these the lower quartzites. 

The Wasatch is probably a complete anticlinal fold.

PEALE,22 in 1873, states that the base of the mountains near Ogden 

is for the most part a red syenite which passes into granite and gneiss, 

and contains in places veins of hornblende, quartz, and specular iron. 

The granites of Cottonwood creek are conspicuously bedded, the dip 

being about 50° or 70° to the east, and they contain rounded pebble-like 

masses of a dark color inclosed within the gray matrix. These granites are cut by veins of feldspar. The pebble-like masses suggest that 

the formation is metamorphic.

BRADLEY, 18 in 1873, regards the core of the Wasatch as metamorphic. 

The occurrence ot angular and rounded patches of dark material in the 

granite of the Little Cottonwood canyon is'taken as evidence that 

these were pebbles of a conglomerate before its metamorphism. The 

rocks are chiefly hornblendic gneiss and syenite, with quartz veins.

Ho WELL 31 , in 1875, states that in Eock canyon, near Provo, pebbly 

chlorite-schist is uncouformably below hard quartzite.

EMMONS, (S. F.)6, in 1877, describes the Wasatch range as a sharp 

north and south anticlinal fold over preexisting ridges of granite and 

unconformable Archean beds, the axis being bent and contorted by 

longitudinal compression so that at times it assumes a dkection approximately east and west. In connection with the folding. is a widelyspread system, of faulting and dislocation, in a direction generally parallel to the main line of elevation, which has cut oif and thrown down 

the western members of the longitudinal folds and the western ends of 

the transverse folds, and they are now buried beneath the valley plains. 

In the northern region is a second broad anticlinal fold to the east of

the main line of elevation. This mountain range occupies the line of 

former Archean uplift, around which were deposited a thickness of 

30,000 or 40,000 feet of practically conformable beds extending upward 

from the Cambrian to the Jurassic. At the base of the Paleozoic is the 

Cambrian formation, which has a small thickness of calcareous slates 

bearing Primordial fossils and a great thickness of white quartzite, including a few micaceous beds and argillites, the whole being 12,000 

feet. The granite mass constituting the center of the Wasatch was 

not protruded through the sedimentary rocks, but the latter were deposited around them, and their present conditions are due to subsequent 

elevation, flexure, dislocation, and erosion.

In the Cottonwood canyons is a large mass of granite which shows 

a conoidal structure, and, while massive, has distinct planes of cleavage 

which dip 50° to the westward. It is a white, rather coarse grained 

granite, dotted here and there with round, black spots where there has 

been a concentration of the dark green hornblende, which is a prominent constituent of the mass. On the western flanks of the Cotton-
VANHISB.] THE CORDILLERAS. 291

wood granites are some remnants of Archean quartzites and schists, 

which have a general strike northeast, and dip from 45° to 60° to the 

westward. At the mouth of the Little Cottonwood canyon they consist of a body of quartzites about 1,000 feet in thickness. These quartzites are different from the Cambrian quartzites of the Big Cottonwood 

canyon; they contain mica in varying quantity, and where this is 

abundant approach a true mica-schist. Toward the mouth of the canyon the mica is replaced by hornblende. BetAveen the Cottonwood 

canyons is about 2,000 feet of Archean slates, quartzites, hornblendeschists, and mica-schists. The Cambrian slates above the granites oi 

the Cottonwood stand at an angle of 45° dipping to the northeast. It 

is difficult to tell whether the granite should be considered as a part of 

the main granite body, which it does not resemble very closely, or-with 

the later outbursts of granite-porphyries and diorites which intersect 

the sedimentary beds of this region. These dikes are very frequent, 

especially around the Clayton peak mass, and in the region where the 

mineralization of the beds has been most developed. One of these in 

the Wasatch limestones is a dike 20 feet wide of syenitic graniteporphyry. The Paleozoic beds of the Cottonwood canyons, which fold 

around and partly cover the granite bodies, have been subjected to intense compression and local metainorphism, and cut by intrusive dikes 

and mineral veins.

The Farmington Archean body is composed of a conformable series 

of gneisses, mica-gneisses, and quartzites, 12,000 or 15,000 feet thick, 

which dip westerly at about 15° or 20°. The lowest part of the series 

is coarse and structureless, but it grades up into an evenly bedded 

rock.

HAGUE,6 in. 1877, describes the northern Wasatch region and the 

region north of Salt lake. The geological structure of the Front range 

remains of the same type as to the southward, but the Archean rocks 

are less abundant. In the lower canyon of the Weber river are rocks 

like the Farmington Archean body, which have, however, a westerly 

dip of 40°. The Cambrian quartzite of Ogden peak lies unconformably 

on the edge of the Archean beds. In the Ogden canyon the quartzite 

is occasionally conglomeratic, containing pebbles of quartzite and jasper. These pebbles are sometimes flattened and elongated in almondshaped bodies, and are frequently distorted and banded into curious 

forms. Sometimes two or more pebbles are pressed together so as to 

form apparently one mass. The flattened pebbles appear Avith their 

longer axes in parallel planes.

KiNGr,7 in 1878, states that on the west side of the Wasatch is a fault 

which has thrown the layers downward from 3,000 to 40,000 feet. The 

Archean rocks occupy the core of the range. Above these is unconformably exposed in the Cottonwood canyons a conformable series of 

Paleozoic strata 30,000 foot thick. The nucleus of the Archean rocks 

in the Cottonwood area is a mass of granite and granite-gneiss. This
292 PRE-CAMBRIAN ROCKS OF NORTH AMERICA.. [BULL.88.

rock at Clayton's peak possesses the physical habit of a truly eruptive 

granite and has been the center of local metamorphism, but the evidence points to the belief that it is of Archean age. In the Cottonwood canyon there is no sharp division between the structureless granite and the bedded gneissoid form. In the neighborhood of Olayton's 

peak are bodies of granite-porphyry which are probably a dependent 

of the granite. West of the granite body of Little Cottonwood canyon 

is a belt of Archean schists and quartzites having a thickness of 2,000 

or 3,000 feet and dipping at a high angle to the northeast. In the Little Cottonwood canyon the quartzites are in junction with the granite, 

while at the mouth of Big Cottonwood canyon, in direct contact with 

the granite is mica-schist. Between the Archean granite and the crystalline schists there are no transitions such as to lead to the belief that 

the granite is a more highly metamorphic form of the schist. The contact is clearly denned, the rocks niineralogically dissimilar, and the 

granite is either an intrusive mass, or else an original boss over which 

the Archean sedimentary materials were deposited. The absence of 

granite dikes in the schists strengthens the belief that the granite is 

older. The Cambrian rocks are in such a position as to indicate that 

the granites and schists alike antedate them, although in some instances intrusive dikes do cut the marbleized limestone, but they are 

middle-age porphyries, not to be confounded with the Archean crystalline rocks.

In the next Archean mass to the north the Farmington area in 

Sawmill canyon, there seems to be two distinct series. The later series 

consists of conformable beds of gneiss, quartzite, and hornblendeschist, which dip west at angles from 15° to 40° , and rest unconformably upon an intensely metamorphosed material composed of quartz, 

orthoclase, and muscovite. In reference to the Farmington gneisses it 

is said: A mica-schist passing into a hornblende-schist, or a hornblende-schist into a granite, or a gneiss rock into an argillite, along 

the line of their longitudinal extensions, are phenomena which fail to 

appear on the fortieth parallel. The small granitoid body in Sawmill 

canyon is referred to the Laurentian, while the second series of metamorphic rocks, comprising the gneisses and schists, 12,000 or 14,000 

feet thick, are referred to the Huronian, as are also the argillites of 

Salt lake islands.

The Paleozoic series of the Wasatch, although 30,000 feet in thickness, show in their lowest portions only a very slight tendency to become 

crystalline schists. The pre-Cambrian topography of the northern part 

of the Wasatch was that of dome-like peaks with gently inclined 

sides. The Cottonwood canyons, however, presented an almost precipitous face of 30,000 feet to the westward. The height of the range 

was then, therefore, from 17,000+ feet to 30,000+ feet.

Passing upward from the Archean, at the base of the Paleozoic 

slates are Lower Cambrian slates and dark argillites and intercalated
VANHISK.] THE CORDILLERAS. 293

siliceous schists 800 feet thick; above this Cambrian quartzite, an immense series of siliceous and'arkose rocks 12,000 feet; and above this 

Cambrian calcareous shales of variable thickness, and containing Primordial fossils, 75 to 600 feet. This great thickness is found in the 

Cottonwood area, on the lower half of Big Cottonwood canyon, and 

from Big Cottonwood canyon in a northeasterly direction across the 

spur which divides the waters of Cottonwood creek from Mill creek. 

In other localities the Cambrian is far thinner or wholly absent. The 

section in the Big Oottonwood canyon, in passing upward, comprises 

black slates and thinly laminated argillites 800 or 900 feet in thickness; 

above these, 8,000 or 9,000 feet of mixed siliceous schists and argillaceous schists; above these, 3,000 feet of true quartzite capped by 200 

feet of schistose rock, quite micaceous toward the bottom, and at Twin 

peak approaching a true mica-schist, At the second section the series

consists of four members: the bottom slates, 800 feet thick; varying 

siliceous and argillaceous schists, containing some mica-bearing zones, 

8,000 or 9,000 feet thick; salmon colored and white quartzites, intercalated with dark schists, 2,500 to 3,000 feet; and the capping schists 

of 200 feet, which are partly argillaceous and calcareous rocks and 

partly mica-bearing argillites. Passing up the Little Cottonwood, the 

successively higher members of the Cambrian rest against the granite 

until the latter rises into contact with the Silurian limestone, which 

conformably overlies the Cambrian. Although a careful search was 

made in these schists no fossils were found.

GEiKiE, 32 in 1880, discusses the nature of the pre-Cambrian mountains 

of the Wasatch and the eruptive or metamorphic origin of the Cottonwood granite. That this granite is eruptive is maintained on the 

grounds of the enormous height of the cliff which would be required in 

case it was an Archean island; that if it were an old shore line, somewhere granite pebbles would be found to-day; that the granite is said 

by King to be a source of local metamorphism; that there are porphyries cutting the limestones, probably dependent on the granite; and 

that it is exceedingly improbable that there was a cliff 12 miles high, 

which has been turned over on its back as required by the descriptions 

and sections by King. All these difficulties are overcome by regarding 

the granite as a subsequent intrusive of post-Carboniferous age.

WALOOTT,33 in 1886, describes the Big Cottonwood canyon section of 

Cambrian rocks, which is found to be 12,000 feet thick. It consists of 

shales, quartzites, sandstones, and slates. The upper 250 feet of shale 

bears the Olenellus fauna, while other layers, although in a most excellent condition for finding fossils, did not reveal any. The Olenellus 

horizon is placed at the base of the Middle Cambrian and the great remaining part as Lower Cambrian.

EMMONS, (S. F.), 34 in 1886, discusses the possibility of the post-Cambrian eruptive character of the Cottonwood granite. This body occupies an area of about 7 by 15 miles, and a thickness of some 5 miles of
21)4 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

sedimentary rocks abnts against its northern side, the principal members sweeping around and in part covering its eastern portion and continning southward in an almost horizontal position. There is no especial 

disturbance of these beds in contact with the granite so far as observed. 

Neither are any masses or fragments of sedimentary rock included in 

the granite. Regional metamorphism exists in changing the sandstone 

to quartzite and limestone to marble, and porphyry dikes cross the 

sedimentary strata, but these have no necessary connection with the 

granite. If the granite is an intrusive mass cutting the Carboniferous 

strata, it is necessary to believe that it has assimilated or eaten up over. 

500 cubic miles of sedimentary rocks. If it has done this it has left no 

trace of fusion in the adjoining rock, and without showing in its own 

structure and position any marked variation from that of a normal 

rock. It is further difficult to understand where the great supply of 

heat is to be obtained to do this work.

WALCOTT,35 in 1889, places the Olenellus horizon at the base of the 

Cambrian and the great series of conformable siliceous rocks, 11,000 

feet thick, below this zone as pre-Ca\nbrian or Algonkian rocks.

VAN HiSE,9 in 1889, made an examination of several canyons of the 

Wasatch. While the Cotton wood granite mass has a regular structure which is seen in the great cliffs, it is apparently completely massive, even in huge blocks. The apparent lamination is due to the 

parallel arrangement of the minerals, which have crystallized with 

their longer axis in the same direction. The lamination of the granite 

is not more marked than is the case with some of the unmistakable 

gabbros of the Keweenaw series. An examination of the granite in 

thin section shows that the feldspars have universally a well marked 

and beautiful zonal structure, such as is known only in eruptive rocks.

Sections of some of the black bowlder-like areas so common in the granite differ from the mass of granite only in that hornblende is more plentiful. The main Cottonwood mass and Clayton peak granite are 

identical in character. In places the sedimentary rocks, and especially 

the limestones, are exceedingly metamorphosed. In one place, near 

the head of Little Cottonwood canyon, at a contact with the granite it 

was exceedingly difficult in the field to tell where the white granite 

ended and the crystalline marble began. In thin section there is no 

difficulty in separating the marble and granite, so that there is no 

transition here. However, the granite became a true porphyry in 

places, a fact difficult of explanation unless it is regarded as a later 

intrusive.

In the Cambrian of the Little Cottonwood was found a conglomerate 

which carries unmistakable granite pebbles and black fragments which 

were thought in the field to resemble the black hornblendic areas so 

often mentioned in the granite. These, however, when examined in 

thin section were found to be entirely unlike those contained in the 

granite. The granite fragments are small and sparse and do not appear to be lithologically like the massive granite of the Cottonwood.
VANHISB.] THE CORDILLERAS. 295

An examination of the Weber canyon of the Farmington area showed 

that the rocks, instead of always having a western dip as described, 

are most intricately and minutely folded and dip both east and west, 

although having a general sameness of dip for considerable areas. In 

this canyon and in Sawmill canyon a search failed to find evidence of 

unconformity between two series of Archean rocks. The schists 

and gneisses are cut by pegma title granite veins in the most irregular 

and intricate fashion. The main mass of the lower part of the Sawmill 

canyon Archean is a series of schists. In going up the canyon, granite.begins to appear cutting the schists, and becomes more and more 

prominent until it is the most abundant material. It is here exceedingly coarse, and the whole appearance is that of an intrusive which 

has cut the schists and gneisses by numerous apophyses. It is probable that the small area referred to by King as being the older unconformable Archean was not found.

LITERATURE OF THE PROMONTORY RIDGE, FREMONT ISLAND AND ANTELOPE ISLAND

RANGES.

STANSBURY,1 in 1853, states that granite, gneiss, mica-schist, slate, 

and hornblende-rock occur at Antelope and Freniont islands. On the 

west side of Freniont island is a bold escarpment 100 feet high of talcose slate, overlain by granite and gneiss. On Promontory point micaslate and limestone were seen. c. -

HAGUE," in 1877, finds the promontory of Great Salt lake to consist 

of quartzites and mica-bearing schists in a conformable series, dipping 

to the west about 38°, and estimated to be 3,800 feet'thick. In the 

middle of the series is a zone of calcareous sandstone, within which are 

several beds of limestone. In the vicinity of Promontory station the 

Archean schists are overlain by limestones. On Fremont and Antelope islands are outcrops of Archean rocks. That of Fremont island 

consists of horublendic and micaceous gneisses, dipping to the west, 

while that of Antelope island is mostly gneisses with some quartzites 

and mica-slates, one of these beds becoming calcareous and approaching a limestone.

LITERATURE OF THE OQUIRRH MOUNTAINS.

HAYDEN,21 in 1873, describes regularly stratified quartzites as resting 

upon a series of granitoid strata in the Oquirrh mountains at the south* 

end of Salt lake. The quartzites pass up into micaceous clays or shales, 

then into limestones. The lower beds of quartzite and limestone are 

probably of Silurian age, and it is known that the second limestone is 

of Carboniferous age.

EMMONS, (S. F.),G in 1877,'finds granite-porphyry in the foot-hills of the 

Oquirrh mountains, and in the same range, at the head of Bingham 

canyon, are diorite dikes which resemble those of the main Wasatch 

range.
296 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL.86.

LITERATURE OF THE AQUI MOUNTAINS.

EMMONS, (S. F.),6 in 1877, describes at Bonneville peak a body of white 

quartzite not less than 6,000 feet in thickness dipping to the westward. 

In this quartzite arebeds of conglomerate strata, the pebbles of which are 

flattened and of argillaceous rock, containing mica and becoming imperfect mica-schists like those east of Farming-ton. This series is regarded 

as equivalent to the Cambrian of the Wasatch on lithological grounds, 

because it rests below a great limestone formation and because it is 

thicker than any of the higher quartzite series of the Wasatch. On 

Grantville peak a similar series is found.

KiNG-,7 in 1878, describes in the ridge east of Egan canyon as occurring directly over the granite several thousand feet of quartzitic schists, 

capped by about 50 feet of highly laminated fissile argillites, which are 

quite similar to the quartzitic schists of the Wasatch

LITERATURE OF THE RAFT RIVER RANGE.

HAGUE,6 in 1877, describes in the Raft river range a considerable 

body of structureless medium, grained granite, forming the central mass.

LITERATURE OF SOUTHERN UTAH AND SOUTHEASTERN NEVADA.

GILBERT,36 in 1875, states that the judges of the Basin range system 

are in part composed of granitic and cognate rocks. The granite occupies various positions. Often it is the nucleus of the range against 

which inclined strata rest. Elsewhere it appears in dikes, traversing 

either the sedimentary rocks or other granites. In a lew instances it 

was observed to overlie the sedimentary rocks, while in a number of 

localities the evidence of its eruptive character is unequivocal; in

others it is plainly nietamorphic, and in by far the majority of cases it 

appears to have assumed its relation to the undoubted sedimentary 

rocks before the upheaval of the combination. In the Granite mining 

district the section shows a white crystalline marble overlain by granite, which appears to extend from the summit of the range to the opposite base. The axis of the Snake river range consists of quartzite and 

limestone, with a limited amount of crystalline schists and granite. 

Metamorphic sedimentary rocks of undetermined age were seen at a 

number of points and have been regarded provisionally in mapping as 

Archean, with which have been grouped the granitoid rocks.

MARViNE,37 in 1875, states that crystalline rocks are found on the 

Salt lake road in the Virgin mountains.

HowELL,31 in 1875, states that Granite rock is an island of granite 

in the desert, which shows traces of bedding, with a high dip to the 

west. The nucleus of Snake range is granite, exposed at many places, 

and overlain by quartzite, shale, and limestone.
VANHISE.] THE CORDILLERAS. 297

SUMMARY OF RESULTS.

In the Uinta mountains the much folded, banded, and contorted 

granitic rock (so-called quartzite) of Bed creek canyon, in its crystalline character, in the intricate way in which it is folded and is cut by 

ancient metamorphosed basic eruptives, is more nearly analogous to the 

fundamental complex of other areas in the West than to the Huronian, 

as has been before suggested.

The lithological analogy between the overlying Uinta series and the 

Huronian Sioux quartzites, mentioned by Hay den, is very close indeed, 

but can. be considered as a guide of no great importance. This great 

series of sandstones, quartzites, and shales, unconlorinably below the 

Carboniferous and separated by a great unconformity from the fundamental complex, may, so far as present certain knowledge goes, belong 

anywhere from the Devonian to the Algonkian.

That it is the equivalent of the Weber conglomerate of the Wasatch 

and belongs to the Carboniferous, as tentatively placed by the Fortieth 

Parallel survey, is not likely. Its great thickness, its separation by a 

very considerable unconformity from the fossiliferous Carboniferous, 

and its lithological character, combined with the fact that a careful 

search by different observers has revealed no fossils, make it probable 

that it belongs as low in the geological column as the great basal quartzite series of the Wasatch, in which case it is Upper Algonkian. It 

is not certain that the series does not occupy a still lower position, perhaps being equivalent to the Huronian, as already suggested.

The general structure of the Wasatch, as explained by the Fortieth 

 Parallel surveyors, stands untouched by later work; that is to say, 

there is here a great series of pre-Cambrian rocks, against which was 

deposited unconformably an immense thickness of clastic deposits, and 

the abrupt western face of the Wasa.tch is due to a great fault.

Passing to details, it is plain that G-eikie's objections to the pre-Cambrian 'character of the Cottonwood granite mass have great weight. 

However, it is to be said that while the difficulties involved in the 

explanation of the Fortieth Parallel surveyors is considerable enough, 

they do not appear to the writer to be so great as indicated by Geikie. 

The pre-Cambrian mountain represented in the sections, instead of 

being 12 miles high, is but half of that height, since its height is not 

ascertained by measuring its horizontal base, but by the perpendicular 

distance between the extension of the Cambrian basal beds and the 

topmost granite. Also, if the stratified beds are supposed to be deposited about the mountain with a slope away from it, as is common 

along a steep shore line, the altitude of the mountain would be even 

less than this. This estimate does not provide for the increased altitude which the mountains must have had before being buried. If the 

section is turned back so as to represent the stratified rocks as horizontal, the average steepness of the granite to its culminating point is 

found to be in the neighborhood of 45°, the lower reaches being lesa
298 PEE-CAMBRIAN ROCKS OF NOKTH AMEEICA. lBwu.86.

than this, but the steepness increasing to more than this amount in 

the upper slopes of the mountains. If the strata are considered as 

originally deposited with a dip of 10° away from the mountains, this 

would reduce the average slope of the mountain to 35°. Even with 

these allowances it is to be said that a buried slope of this degree of 

steepness, which is covered by the debris of an advancing shore line 

with the additional altitude of the mountains required in order to furnish the surrounding debris, seems highly improbable.

So far as facts were observed by the writer bearing upon the question of the character of the Cottonwood granite, they tend in the same' 

direction as Geikie's conclusion. If this granite is supposed to be a 

later intrusive, the rnetamorphisni of the sedimentary beds noted by 

the Fortieth Parallel surveyors, the- presence in them of the graniteporphyry dikes, the sharp contacts and manner in which this eruptive 

mass cuts across the Archean crystalline schists at the foot of Little 

Cottonwood canyon, are all explained. In this connection it is to be 

said that so far as known the zonal character of the feldspars so well 

displayed by this rock is nowhere found in such perfection in such, 

ancient rocks as the pre-Oambrian, although this point may not be one 

of much weight. If the granite is an eruptive, the contained round 

black areas described by nearly all observers, and early taken as evidence that the granite is metamorphic, must either be partially absorbed 

fragments caught by the eruptive mass, or else segregations of hornblende which formed at the time of the crystallization of the rocks. If 

the post-Cambrian eruptive origin of the granite be accepted, there is 

no necessity for considering the Wasatch fault of such great magnitude and the pre-Cambrian mountains of almost incredible steepness 

and height.

Upon the other side, it must be said that' if the estimate given by 

Bminons of the amount of sedimentary material of necessity absorbed 

by the eruptive theory 500 cubic miles be correct, it is almost an 

equal strain upon belief. In this connection the question arises whether 

a closer study of the region will not show that the Cambrian strata 

have a quaquaversal arrangement about the Cottonwood granite as do 

the Silurian, Devonian, and Carboniferous strata, the edges of the 

Cambrian being uptilted, and, like them, the structure as a whole being 

batholitic. While it may be found that the entering granite has absorbed a portion of the Cambrian quartzite, the amount thus assimilated would be comparatively small. On this hypothesis the present 

distribution of the rocks would be explained by intrusion and erosion.

The relations of the elastics to the much larger Farmington and 

northern Archean areas, unquestionably older than the sedimentaries, 

are such as to require comparatively low and relatively gentle slopes 

and pre-Cambrian mountains not higher than from 12,000 to 18,000 

feet; that is, mountains not higher than those at present existing adjacent to the ocean.
VANHISE.] THE CORDILLERAS. 299

In the Wasatch, among the rocks which the Fortieth Parallel survey 

pleiced as pre-Cambriau, the writer was able to find no rocks Avhich are 

not completely crystalline. An examination of the specimens collected 

by that survey showed no clastic rocks. In the Farmington area the 

crystalline schists and gneisses are cut by coarse, intrusive granites; 

hence, so far as at present known, aside from the usual fundamental 

crystalline complex, there is no evidence of any rocks below the conformable succession placed in the Paleozoic, excepting the small area of 

quartzites and quartzose mica-schists at the foot of the Cottonwood 

canyons. The reference of the basement complex of the Wasatch to 

the Huronian on lithological grounds by the Fortieth Parallel survey 

could have been made only by a mistaken conception of the real character of that series. This complex is lithologically much more nearly 

like the crystalline complex of rocks usually referred to the LaurentianThe calcareous argillites, limestone, and the quartzites occurring on 

Antelope island and Promontory ridge are of a different lithological 

character from the main area of Wasatch Areheau and may represent 

a later series of rocks. To this series the Lower Cottonwood schists 

may also belong. There is no decisive structural evidence in the nature 

of known contacts-showing that these rocks are older than the lower 

part of the succession which was referred to the Paleozoic, but the 

latter series is nowhere so crystalline, and the fact that these rocks 

were placed in the Archean rather than the Paleozoic by the Fortieth 

Parallel survey shows that the affinities of these rocks were thought to 

be with the former. Since part of the rocks here included are certainly 

of clastic origin, it appears that there is in this region representatives 

of the Algonkian system.

Below the Olenellus fauna in the great succession of rocks referred 

to the Paleozoic by the Fortieth Parallel survey is a conformable inferior series of quartzites and schists about 12,000 feet in thickness. 

There is no evidence that these are notpre-Olenellus, and they are therefore doubtfully mapped as pre-Cambrian or Algonkian. The descriptions of this series show that it is a considerably altered one. The sandstones have been indurated to quartzites, and the mica-schist of Twin 

peak is quite crystalline. If this reference of the Wasatch lower qnartzite to the Algonkian proves correct, it stands as the uppermost series 

of this system, in a position equivalent to the great series of barren 

slates of Montana, described byDavis and Peale as conformably below 

the Cambrian.

SECTION V. NEVADA, NOETH OF PARALLEL 39° 30'.

LITERATURE.

SOHIEL,38 in 1855, states that in the Humboldt and other island mountains of the desert west of Salt lake are granites, syenites, quartzose 

rocks, and clay-slates.
300 PRE-CAMBRIAN BOOKS OF NORTH AMERICA. [BULL. 86.

EMMONS, (S. F.), and HAGUE,6 in 1877, describe the mountain ranges 

of the Nevada plateau and the Nevada basin.

Granites constitute the entire cores, or a large part of the cores, in 

the following ranges: Ibenpah, Wachoe, Antelope, Schell creek, Egan, 

Franklin buttes, Ombe, Gosi-ute, Peoquob, East Huinboldt, White Pine 

or Pogonip, Wah-weah, Cortez, Seetoya, Shoshone, Toyabe, Augusta, 

Fish creek, Havallah, Pah-ute, West Humboldt, Montezuina, Pah-tsou, 

Granite, Pah-supp, Sah-wave, Truckee, and Lake.

In the hills between Antelope and Schell creek mountains, in the 

Goose creek hills, and in Franklin buttes, granite-porphyry is also found. 

In the Franklin buttes there is a gradation from syenitic granite, 

through granite-porphyry, into genuine felsite-porphyry. The hills 

between the Antelope and Schell creek ranges contain cores of granite, 

east of which are interstratified beds of dolomite, marble, and dikes of 

granitic porphyry. These are considered to represent the development 

of an Archean body.

The granite of the Wachoe range is different in its lithological character from the Eaft, Ornbe, Gosi ute, and Peoquob ranges, and is therefore regarded as eruptive. No decisive evidence shows its age, but it 

is regarded, because of the nature of its occurrence, structure, and min- " 

eralogical habit, as probably Jurassic. The granite of the Fish creek , mountains is structureless and would seem to be an intrusive body. 

The entire mass of the Pah-supp range consists of granites which reseni- ( 

ble the later granite of the Pah-tson range.

The Cluro hills of the Cortez range are composed of syenite-granite, 

which is the only true syenite found in the region.

The Peoquob, East Humboldt, Shoshone, West Humboldt, Montezuma, Pah-tson, Truckee, Lake, and Pea Yine mountains contain, 

besides the granitic rocks, various crystalline slates and schists which 

are regarded as Archean. On Spruce mountain of the Peoquob range 

are mica-schists and mica-slates which probably belong to the older 

series, but the relations are obscure. They are distinctly bedded, finely 

laminated, and similar to the crystalline schist series of the Humboldt 

range. The East Humboldt range, the main range of central Nevada, 

is a mass of Archean rocks, which acts as the axis of an anticlinal fold 

and upon which rest unconformably the Devonian and Carboniferous 

strata. The southern part of the range is composed of granite in two 

large areas, which possesses, at White Cloud peak, the characteristics 

of an eruptive granite, there being no distinct lines of bedding, although 

divisional planes are noticeable. The northern granite mass is unconformably overlain by a series of quartzites, hornblende-schists, and 

gneisses which contains beds of dolomitic limestone from 1 to 6 feet 

in thickness, separated by micaceous quartzites and mica-schists. This 

series, estimated in the northern part of the range to be from 5,500 to 

6,000 feet in thickness, is best seen on Clover canyon and Boulder 

creek. There is every gradation between the coarse gneissoid phases
VANHISB.] . THE CORDILLEKAS. 301

and the fine grained mica-schists. The granite of the Hunaboldt is 

similar to the Laurentian of the Appalachian, while the unconformably 

overlying series closely resembles the eastern Huronian. In the Southern Shoshone range an original Archean island is wrapped around by 

fine grained micaceous slate. The Archean granite of Eavenswood 

peak has remarkably regular bedding planes apparently conformable 

to those of the overlying slates, which give it the appearance of being 

a stratified granite, although it at the same time traverses the slates 

in dikes. The Eavenswood peak granite to the east is essentially different from the Archean granite and is evidently of later origin. In 

the West Humboldt range the granite shows structural planes. Along 

its northern and western edge it is overlain by a series of metamorphic 

schists and gneisses, which are in turn overlain by fine, white, knotted 

schists. The strike of these beds is N. 38° E., and they stand nearly 

vertical. The contact of the granite and schist shows in a horizontal 

plane irregular angular intrusions of the former into the latter, masses 

of schists lying in the granite and extending as promontories from the 

main mass for 400 or 500 feet. The line of demarcation between the 

two bodies is easily observed, and there seems to be no tendency for 

the schists to pass by gradation into the granite. Dikes penetrate 

both the granite and schists. The range is regarded as an anticlinal 

fold. In the Montezuma range are slates and schists which rest unconformably upon the granite. The Pah-tson mountains consist almost 

entirely of granite and crystalline schists, which are cut by numerous 

dikes, the whole being regarded as Archean, because the dikes do not 

cut later eruptive granites, which are found in considerable quantity, 

and differ markedly from those which are regarded as Archean. In 

the Truckee range are found quartzitic schists and hornblendic rocks 

with both older and later types of granite. The metamorphic schists 

cut by intrusive granites referred to the Archean occupy but a small 

area, the later granites making up the greater part of the range. In 

the Lake range are granite and Archean gneissic rocks, which are 

quite unlike any other observed rocks in western Nevada. The Pea 

Vine mountains consist of quartzites and fine grained feldspathic rocks, 

which are referred to' the Archean, but their relation to the other 

crystalline rock masses has not been made out.

In Schell creek, Egan, Pogonip or White Pine, and Pinon ranges the 

granite is overlain by Cambrian strata. In the Schell creek mountains 

are limestones bearing Primordial fossils overlying heavy bodies oi 

Cambrian quartzite. In the Egan range, overlying the granite, is a 

series several thousand feet thick of quartzites and quartzitic schists 

with a 50-foot bed of roofing slate. The main mass of quartzite is 

thoroughly vitrified, showing little trace of granular structure. A portion of the quartzites show evidence of having been submitted to great 

pressure, and the slate at times gets to be micaceous, and even becomes 

a normal mica-schist. This series doubtless represents the Cambrian,
302 FEE-CAMBRIAN EOCKS OF NORTH AMEEICA. [BULL. 86.

but the direct contact of the overlying limestones was not observed. 

Overlying the granite of thePogonip mountains, apparently unconformable with the granite, are outcrops of mica-slate and black arenaceous and 

argillaceous slates and shales, in turn overlain by an undetermined 

thickness of compact vitreous quartzite. Above this quar tzite (regarded 

as Cambrian because resembling the Cambrian quartzites of the other 

Nevada localities) occurs the Pogonip fossiliferous limestone the higher 

beds of which are referred to the Quebec group. In the Pinon range, 

below the heavy Silurian limestone there occurs a heavy bed of red and 

brown quartzite underlain by mica-schists and quartzitic schists 5,000 feet 

in thickness, which from their position inferior to the Silurian and their 

similarity to the Wasatch Cambrian are referred to the Cambrian age.

In the East Humboldt range overlying the granite is quartzite, which 

is referred to the Ogden, but without any overlying rock. In the 

Wah-weah range, surrounding the granite, occurs a heavy bed of 

quartzite, which is referred to the Ogden Devonian, although but little 

examined.

In the Ombe, Gosi-Ute, Peoquob, Little Cedar, Toyano, Fountain 

Head, Cortez, Eiver, Northern Cortez, and Battle ranges the rock overlying the granite is a nonfossiliferous quartzite referred to the Weber. 

These quartzites are generally of a bluish gray color, contain flint and 

chert fragments, often angular, and jasper pebbles, sometimes have thin 

seams of carbonaceous material, are often ferruginous, and not infrequently conglomeratic. At these ranges the Weber is overlaid by heavy 

bodies of limestone referred to the Upper Coal-measures, generally 

carrying fossils to the contact with the quartzite. At most of these 

ranges the quartzite is several thousand feet thick, sometimes as much 

as 6,000 or 7,000. At Pilot peak of the Ombe range, interstratified 

with the quartzites, are mica-schists, and the series resembles the Cambrian of Bonneville peak, Aqui mountains. In the Seetoya and Shoshone ranges the quartzites referred to the Weber are between heavy 

beds of limestones, and in Two Cubits it conformably overlies an 

enormous development-of Wasatch limestone.

The stratified rocks overlying the Havallah, Pah-Ute, West Humboldt, and Truckee granites are referred totheTriassic; that overlying 

the granites of the Pah-supp range is referred to the Jurassic ; while 

the gray slates resting unconformably above the'Sah-wave are referred 

to the Miocene. These references are mostly made on lithological 

grounds, because no Paleozoic strata have been recognized west of the 

Battle mountains, although in certain cases paleontological evidence is 

found.

It is remarked that throughout Nevada are large bodies of quartzites 

without any clue to their stratigraphical relations with an underlying 

or overlying limestone, the adjacent rocks being either granites or Tertiary volcanic outflows. It is then exceeding difficult, if not impossible, definitely to determine their true geological horizons. In many
VANHISE.] THE CORDILLERAS. 303

cases lithological and structural resemblances furnish a strong aid, 

which, when followed up, not infrequently throw the evidence in favor 

of one or the other of the great zones of quartzites; but in many cases 

such resemblances are meager, and the references are made upon theoretical grounds, being upon slight evidence, or even personal impressions received in the field. 

KiNGr,7 in 1878, describes many of the Nevada ranges. .

j In the Gosi-Ute range the Archean rocks are granite, granite-por-

' phyries, and crystalline dolomites, all of which are interlaminated and 

are chemically allied to those of the Hnmboldt range. That the granite-porphyries are interstratified with the marbles confirms the probability of their being inetamorphic.

The Archean of the Humboldt range, \rith the exception of a small 

body of granite, is composed of a conformable series of gneisses, gneissoid schists which are sometimes hornblendic, dolomitic limestones, and 

quartzites, all of which dip to the west. It is evident by the entire absence of easterly dipping Archean and Paleozoic rocks that a fault 

similar to that at the Wasatch has cut dowu the core of the range 

from north to south, and that the eastern half is depressed below the 

level of the Quaternary plain. The White Cloud peak granite bears a

, singular resemblance to some of the Huronian granitoid rocks, also 

conceived to be metamorphic. The granite appears to underlie con-

/ formably the series of schists. The gneisses of Clover peak can not be 

distinguished in hand-specimen from a granite, except that there is an 

indistinct parallelism of its dark constituents. Between this stage and 

the truly schistose gneisses there is every possible transition. The 

limestone series is not over 50 or 60 feet thick, in beds from half an inch 

to 6 feet. Intercalated with the limestones are gneiss and porphyries 

very like those in the Gosi-TJte range. The upper beds pass through a 

transition into the pure quartzites. .The Humboldt Archean schists 

have a family likeness with those of the Farmington region of the 

Wasatch and those of the Medicine Bow.

In the Cortez range a central body of granite is invaded by syenites, 

is overlain on the west by a quartzite, which is, for the sake of convenience, referred to the Weber.

In the Shoshone range the stratified series dip away from the central 

mass, which has rather the appearance of an intrusive core. From 

their likeness to other known Archean rocks, and for want of reasons 

to the contrary, these schists, together with the granite, are referred to 

the Archean. Regular parallel divisional planes are seen in the granite, so as to give it an appearance of stratification, but as it penetrates 

the schists in the form of a dike, there is no doubt of its eruptive 

origin.

In the Havallah range, associated with the older granites, are intrusive granite bodies, but such occurrences are exceptional along the 

area of the fortieth parallel.
304 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL.SC.

In the West Hnmboldt range a variety of crystalline schists are 

found unconformably upon the granite, there being no tendency for a 

passage to occur between the two rocks and dikes of granitic material 

invading the schists. In the schists are roundish areas of quartz, 

which might be explained on the supposition that they are the pebbles 

of conglomerates, but they are more probably an aggregation formed 

during rnetarnorphism.

In the Montezuma range the granite of Trinity peak is undoubtedly 

of eruptive origin, as may be determined from its general habitus and 

from its penetrating the Archean schists in well denned dikes.

In the Pah-tson range the Archean nucleus consists of crystalline 

schists, a limited amount of granite, and a subsequent granite which 

has cut through the older granites and schists. These are all cut by 

dikes of later age, but supposed to be Archean.

The Truckee range is composed of schists and granite representing 

two periods of formation.

The Pea Vine mountains consist of a series of conformable, highly 

altered beds, striking from north 50° to 65° east, made up for the most 

part of fine grained quartzite strata, riven in every direction with minute fissures, which are filled with ferruginous material. .

It is remarked that in the absence of any granitic dikes penetrating 

the stratified series, or of peculiar local metainorphism, or general evidence of intrusion, the bodies are usually referred to the Archean. 

Only in cases where the granite is actually seen to penetrate the openings in the strata is it safe to refer it to a later age than the sedimentary series. 

In the analytical map the rocks are divided into two classes, the intention being to discriminate those formations which are sedimentary from 

the class of eruptive rocks; but this line can not be drawn with precision, because the series of gneisses pass into the massive layers and 

because limited bodies of granite which" are massive might if more 

largely exposed pass into crystalline schists or other Archean sedimentary rocks.

It is not easy to analyze those subtle appearances which lead the 

observer to incline to one or the other of the two possible modes of origin of a granite outcrop. Parallelism of bedding, and even parallelism 

of the arrangement of minerals, are consistent with the theory of an 

eruptive origin. Certain masses of gneissoid granite appearing in 

the great eruptive granite body of the Sierra Nevada show quite as 

much parallelism of bedding and internal arrangement of minerals as 

the Eocky mountain granites to which we have assigned a metamorphic origin; yet the Sierra field, as a whole, is clearly eruptive. But 

at the same time, in the intimate arrangement of the mineral particles 

and in the mode of contact between the various mineral ingredients^ 

there is a certain broad uniformity in all the eruptive granites which 

produces a characteristic impression upon the eye, On the contrary^
VANHISE.] THE COKDILLERAS. 305

tlie granites which we conceive to have been of metamorphic origin, no 

matter how simple the mineralogical composition, have always a peculiar variability of arrangement; and even in the absence of any pronounced parallelism, they show the effect of interior compression and 

irregular mechanical influences. On the one hand, in the eruptive 

granites there seems to have been a steady expansive force, doubtless 

due to the heat and elastic fluids, which gave to all the particles a certain independent polarity, while in the metamorphic granites they seem 

to have been crowded into constantly conflicting positions. As the 

result of this, the crystalline particles of the metamorphic granites are 

much less apt to have completed their crystallization, or, if it was completed, they have been crushed and torn asunder and their particles 

scattered, while in the case of the eruptive granites crystallization 

seems to have been more perfected. The result of this is to give to the 

eruptive granites something of the uniformity of texture of a volcanic 

rock, while all the metamorphic granitoid rocks, when once the gneissoid parallelism of minerals is broken up, have a crushed, irregular, 

and contused mode of arrangement.

The metamorphic rocks of the Huniboldt mountains, Franklin buttes 

and the Kinsley district are provisionally correlated with the Huronian 

of Canada.

The foregoing ranges are referred to the Archean simply on petrologi- 

' cal evidence. This mode of correlation is dangerous, but a general 

, study of the whole region has strengthened the belief that in the Paleozoic series as a Avhole there are none of those results of extreme 

metamorphism which in the Appalachian system are described by some 

geologists as closely approximating to Archean forms.

Besides mentioning localities given by Hague in which Cambrian is 

found, it is said that an excellent exposure of Cambrian schists and 

quartzites is found underlying the, Pogonip limestone, in the range of 

hills including the Eureka Mining district and connecting the Diamond 

and Pinon ranges.

HAGTTE,39 in 1883, describes the Eureka district as a mountain block 

standing between the Piuon and Diamond ranges. At the base of the 

series is the Prospect mountain, quartzite, 1,500 feet thick, over which 

is a shale 100 feet in thickness bearing the Olenellus fauna. One small 

area of granite is found. The Prospect mountain quartzite lies in contact with and dips away from it in irregular broken masses.

WALCOTT,33 in 188G, describes the Eureka series of Nevada as middle Cambrian and finds at the top of the Prospect mountain quartzite 

the Olenellus fauna. In the adjacent Highland range a more abundant 

fauna is found in the lower 1,500 feet of quartzite.

WALCOTT,35 in 1889, places the lower quartzite of the Eureka and 

Highland sections as basal Cambrian. 

Bull. 86 20
306 PRE-CAMBKIAN EOCKS OF NORTH AMERICA. [BULL.86.

SUMMARY OF RESULTS.

It is evident that west of the Wasatch no such detailed and careful 

work was done by the Fortieth Parallel Survey as in that range and in 

the ranges to the east. In the Nevada ranges, which contain granite 

only, the reference of the rocks to the Archean or to a later period is 

based upon too little evidence, and it can only certainly be said that in 

each case the granites are older than the oldest sedimentary rocks with 

which they are in contact and do not cut. Some of the granite areas 

are said to be as late as the Jurassic, as for instance that of the Washoe 

range, which is in eastern Nevada. That this is an intrusive could be 

determined, because it cuts the pre-Jurassic rocks; but in the numerous 

cases in western Nevada the undisturbed sedimentary rocks adjacent 

to the granite ranges are Triassic or Jurassic; so that granites earlier 

than these periods, but far later than the Archean, would show no 

structural evidence of their late age.

It is now well settled that granitic-textured rocks vary into porphyritic forms, but to the Fortieth Parallel Survey belongs the credit of an 

early recognition of this. In the Gosi-Ute and Franklin butte ranges, 

in which the rocks are referred to the Archean, the granites are said to 

grade into granite-porphyries, and at Franklin butte into a genuine 

felsite-porphyry.

In the G-osi-TJte the granite-porphyry is so associated with crystalline 

limestone, referred to the Archean, as to lead to the conclusion that 

both the granite and granite-porphyry are metamorphosed sedimentary 

rocks. It seems far more probable that they are eruptives later than the 

crystalline limestone and have been the cause of its metamorphisra. 

This explanation was applied by the Fortieth Parallel surveyors to the 

case of the interstratification of marbles and granitic porphyry in the 

hills between the Antelope and Schell creek ranges. In the western half 

of Nevada, especially, are abundantly found late rhyolites, trachytes, 

porphyries, etc., so that it may be said that this has been a region of 

great volcanic activity until late time, the chemical composition of 

many of the rocks being the same as granite. While probably mistakes 

have been made as to the age of the granites in individual cases, the 

general point which King makes that the ancient granites have a 

crushed, irregular, and confused mode of arrangement of the minerals is 

one of considerable weight, although it would have no bearing upon 

their origin; for this condition of the minerals would by many geologists be taken as merely evidence of powerful dynamic action which 

has produced the present confused condition in an eruptive granite, 

rather than the result of metainorphic processes upon a sedimentary 

rock. The exhibition of these characters by one mass of granite and 

their lack in an adjacent one, indicates that the former is of greater 

age because the other has escaped the effects of dynamic action.

In the cases of the Schell creek, Egan, Pogonip, and Pinon ranges, 

where below the Olenellus Cambrian there is a great thickness of in
VANHISE. ] THE CORDILLERAS. 307

, ferior conformable nonfossiliferous quartzite and then an unconformity 

before the rocks are reached referred to the Archean, the conclusion can 

not be questioned. Also it is probable that where there is a complex 

of granite, gneiss, and schists (as in many of the mountain ranges), 

precisely like that found elsewhere in the West, and known to be preCambrian, the lithological evidence for reference to the Archean is suf-

; flcient. Among such ranges are the Cortez, Shoshone, Havallah, East

I and West Humboldt, Montezuma, Pah-tson, Truckee, Pea Vine, and

/ others.

The question as to the separability of the rocks referred to the Archean into two series is hardly touched. In the East Humboldt it is 

evidently thought that the White Cloud peak granite is older than the 

schistose series, the former being regarded as Hurooian and the latter 

apparently as post-Huronian. One wishes that more evidence were 

given that the granite mass in this case does not cut the schists and 

gneisses as in most of the other ranges. This is especially true because

- Hague says the White Cloud mass has the characteristics of an erup.

f tive rock. More often the granites cut the overlying schists, as in the

Shoshone, Havallah, West Humboldt, Montezuma and Pah-tson ranges,

 so that all of the rocks referred to the Archean are in these ranges

,basernent complexes.

' Whether there is in any of the northern Nevada ranges genuine 

elastics which are placed among the Archean is not positively deterxmined. The quartz-schists, limestones, and mica-schists of the Humboldt range seem to be such a series, although they have now become 

very crystalline by dynamic action. In the West Humboldt range in 

the schists are mentioned fragment-like areas of quartz, which are

/explained to be aggregations formed by metamorphism. In the Pea

'Yine range there are quartzites. While from the descriptions there 

is no definite indication that truly clastic series exist elsewhere, 

such may hopefully be searched for in the Peoquob, Shoshone, West 

(Humboldt, Montezuma, Pah-tson, Truckee, with perhaps a greater 

probability of success in the Shoshone, Peoquob, and Truckee. 

If the lower 10,000 or 12,000 feet of quartzite in the Wasatch below

' the lowest fossiliferous horizon belong with the pre-Cambrian rocks, as 

suggested in the previous section, it is probable that parts of the 

qiiartzites below the Primordial fauna in Schell creek, Egan, Pogonip, 

and Piiiou ranges belong in the same series that is, the Upper Algonkian.

It is possible that several of the quartzites referred to the Ogden 

and Weber belong much lower in the geological column than supposed, 

for it is stated that in some cases these are referred to the Weber or 

Ogden for the sake of convenience, upon the slightest lithological evidence, or the mere personal impression of the observer. Some of these 

may be as low as Upper Algonkian. The series referred to the Weber, 

which in its lithological character is most similar to the Algonkian, is
I. 

308 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

that in the Ombe range, where interstratified with the quartzite are 

seams of mica-schists.

Upon general principles it appears improbable that an equivalent to 

the Weber quartzite of the Wasatch should so widely be a basal formation. That a quartzite should be the lowest formation adjacent to 

an earlier mountain range is what one would expect, but that in so 

large a proportion of the ranges should now be found exposed as the j 

basal series the same division of a single period is contrary to proba- j 

bility. ^ x

SECTION VI. COLORADO AND NORTHERN NEW MEXICO.

LITERATURE OF THE FRONT RANGE, NORTH AND EAST OF THE ARKANSAS.

LONG,40 in 1823, describes granite as succeeding pudding-stone or conglomerate on Defile creek. The granite is coarse grained and rapidly 

disintegrates. A high peak was ascended and was found to consist of 

an indestructible aggregate of quartz and feldspar, with a little hornblende in small particles.

HAYDEN,3 in 1869, states that all the mountains east of the South 

park have a gneissic and granitic nucleus. Each of the great ranges 

of the park are anticlinal axes with massive granite cores and gneissic:. 

granites inclining from each side in the form of ridges. The trend of \ 

the ranges is in most cases northwest and southeast or nearly so. The v 

Azoic rocks have two planes of cleavage, one of them with a strike 

northeast and southwest, and the other at right angles. Besides these^ 

cleavage planes there are in most cases distinct lines of bedding. At 

Golden city the sandstones lie close to the metamorphic rocks, inclining 3Qo to 540.

MiuviNE,41 in 1874, describes fully the metamorphic crystalline rocks j

of the Front range. The rocks of this great area are mostly composed 

of schists, gneisses and granites. Disregarding unimportant occur-' 

rences of undoubted ancient eruptives, as well as some minor granite 

areas of uncertain nature, the series as a whole must be regarded as a N 

system of ancient sedimentary rocks which have undergone the most 

profound metamorphism, the result of which over large areas has reached x 

the last term, structureless granite. Considering the extent and antiquity, the formation as a whole is remarkably simple and uniform, 

running from quartzite through siliceous and mica-schists to very simple varieties of gneisses and granites in which the mica is wholly subordinate. The least metamorphosed rocks observed were excessively hard 

and compact quartzites found in the lower canyons of Coal and Ralston 

creeks. They here pass into a series of highly siliceous schists, in places 

ferruginous, in which may possibly be found workable deposits of iron , 

ore. These are associated with fine siliceous mica schists, above which 

are very irregular schists, intercalated together. Gneissic and granitic strata are frequent, while below is a great granite mass with but 

few remnants of bedding left, but which is apparently conformable with
U.S.GEOLOGICAL SURVEY. BULLETIN 86 PL IX.

UNCLASSIFIED PRE-CAMB. ALGONKIAN POST-ALGONKIAN GRANITE

GEOLOGICAL MAP OF PORTIONS OF COLORADO AND NEW MEXFCO

SHOWING PRE-CAMBRIAN ROCKS 

Compiled from the King.Hayden & Wheeler Reports 

Scale 3.4so~cToo
VANHISK.] THE COKDILLEKAS. 309

the series above. A similar succession was observed near the Little 

Thompson, quartzites being found at the top and granites at the base. 

On South Saint Train's, and at the mouth of South Boulder canyon 

are found quartzite resting upon zoned but structureless granite. The 

Triassic shales rest unconformably upon the mica-schists on Little 

Thompson. The dominant rocks are granitic and gneissic, although, 

schists are found over large areas, and of these the tendency is toward 

a binary granite to which the name Aplite might apply.

That the characters noted above are evidence of a structure that 

once existed throughout the whole mass; that the inclosed schistose 

patches and areas are neither remnants of foreign schists inclosed in 

an eruptive granite mass, nor accidental lamination developed by crystallization or motion in a plastic rock, is abundantly proved by the fact 

that whenever over a continuous area a great many of the strikes and 

dips of such remnants are carefully noted and platted on the map, they 

are invariably consistent among themselves in indicating a definite 

structure of the whole, and accord with the structure that may be indicated by neighboring schists and other masses of undoubted bedded 

rocks.

As in the derived sedimentaries is found the d6bris from the crystalline rocks, it is concluded that the folding which affected the inetainorphism is older than that which has upturned the sedimentary 

strata. It is not supposed that sufficient heat was necessary to cause 

dry fusion, but aqueo-igneous fusion.

While rnetarnorphism alone has often left sharp lines of deinarkation 

, between differently affected rocks, there are also points where movements of the plastic rock seem to have occurred; while, in tracing a 

line of schist into a granite area, points may occur where the normal 

granitoid strata regularly belonging to the series may gradually increase in number and thickness, monopolizing the series and producing a normal metamorphism; or tongues of granite may invade the 

schists, as if an active metamorphism had proceeded outward from the 

granites, eating, as it were, into the schists, and absorbL v first those 

beds by nature most readily succumbing to the change, and leaving 

the intercalated masses less changed. Yet the remnants of structure 

left in the granites still show that no important movement has taken 

place in the mass, but that the rocks remain in situ, and are an indigenous 

granite. But, besides these confusing appearances, lines of the granite 

sometime appear as if aetually injected or intruded among the schists, 

sometimes on their bedding, and perhaps across them as eruptive veins. 

Indeed, there seemed cases where, in approaching the same mass of 

granite from different points, at once all the appearances of a truly 

exotic and eruptive origin might be found abrupt lines of demarkation and veins, while at another point nearly all the steps of a gradual 

metamorphism and transition from the schists beyond might be traced, 

while the remnants of structure through the mass itself would, in
310 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

greater part, conform to the surrounding system of folds, showing it as 

a whole to be an indigenous mass. Two observers thus approaching 

such a mass would justly render different verdicts as to its nature, one 

ascribing to it a wholly eruptive origin, the other a clearly metamorphic character. A few minor masses of granite did not show w&H 

marked transitions from schists, though in part the ends of the latter 

gradually, yet abruptly, merged into the granite, as if absorbed 

by it, the mass as a whole presenting an intrusive character. There 

is, however, no evidence whatever to show that such masses have 

traveled far or that they might not have come from a short distance 

only and have been derived from rocks similar to those in which 

they are inclosed or others of the same series, for their likeness may 

be found at other points as true inetarnorphics. Penetrating various 

portions of the series are granitic, usually mostly feldspathic, veins, 

many of which probably extend long distances and appear to be of 

true eruptive character, while other granitic veins, usually of very 

coarse bluish quartz and white cleavable feldspar, with sheets and 

large crystals of white mica, seem to be more naturally referred to 

infiltration or to be endogenous in character, like many metalliferous 

veins, some of each kind showing layers of deposition or structure.

While it is exceedingly difficult to obtain structural results, a map of 

the eastern slope of the Front range is presented. The portion in which 

the structure is most clearly made out is. that south of South Clear creek 

and having mount Evans as its culminating point. The granite of 

mount Evans occupies as low a geological position as any rocks in the 

range. No special facts bearing on the equivalency of the metamorphic series to any of the divisions of the Archean of the east were observed.

PEALE,42 in 1874, describes several sections in the Front range at 

Pleasant park, glen Eyrie, Bergen park, and Trout creek, in all of which 

the granite underlies the fossiliferous series. On the South Platte, at 

the change from the sandstone to the granite the former contains fragments of. unchanged granite. In other places the sandstone appears to 

pass by gradations into the granite. Pikes peak is composed of fine 

grained, reddish granite, the origin of which, whether eruptive or met-' 

amorphic, is a question. On the road from Colorado springs to South 

park is a granitic ridge which seems to be thrown up through the coarse 

beds which lie about it. In the range of the South park several sections of the fossiliferous series are described which rest upon granite 

or gneiss. At Georgia pass eruptive granite forms the peak, while 

black micaceous gneiss is at the base of the series, there being between 

the two slates and quartzites. At several of the sections given the 

basal layer of the series is a quartzite.

ENDLICH, 43 in 1874, describes granite as forming the heaviest mass of 

rock north and east of the Arkansas and south of the line running east 

and west 6 miles south of Pikes peak. Upon Cottouwood creek the
VANHISB.] THE CORDILLERAS. 311

rock resembles a gneiss. .Besting immediately upon the. granite is the 

Silurian, characterized by but a few fossils, and the well known quartzitic formations. The granite of this a.rea is the oldest found 'in the 

region.

STEVENSON,44 in 1875, states that nietamorphie rocks occur in the 

Front range. On the North fork of the South Platte the schists are 

much contorted. The schists near Baileys ranch contain rudely oval 

nodules of quartz and feldspathic granite which in several localities are 

observed in layers. In many instances the large masses of gneissoid 

granite string out like veins on all sides from the center, and these veinlike projections break up into these nodules and thus finally disappear. 

It is sufficiently evident, then, that these are not metamorphosed pebbles, but concretions, the result of segregation, which marks the formation of the separate layers of quartz, feldspar, and mica in gneiss, and

of the great masses of coarse granite, which occur so frequently in the 

gneisses and schists. Gneissoid granite is exceedingly common. It often 

occurs in the gneiss as great included masses of irregular shape or in 

elongate-vein form, spreading from a center and throwing out seams 

which become exceedin gly thin before they disappear. In each instan ce 

the deposit seems to bear no relation to the bedding of the including 

rock. For the most part, however, it is found entirely displacing the 

gneiss andformiug the prevailing rock for miles. In every such instance, 

however, it occasionally changes into gneiss for short distances. Not 

unfrequently seams of granite a,rc found along the planes of cleavage. 

This granite, which may be termed segregated granite to distinguish 

it from the granite which many regard as eruptive, is coarsely crystalline, with the feldspar in great quantity, while the proportion of mica 

is very small. The feldspar varies in color from white to red, and the 

rock as a whole yields readily under the influence of the weather. The 

gneissoid granite of Taylor river exhibits granite of both the eruptive 

and metamorphic varieties, one passing into the other with no line of 

separation. There is then no room to doubt that they are of common 

origin and that the whole is metamorphic.

The gneiss of Ten-Mile creek is compact and might be mistaken for 

a quartzite. Below the junction is an immense segregation of granite, 

thoroughly veinlike, interlacing and running across the bedding in 

every conceivable way, but not persistent, as each of the veins tapers 

off until it disappears. In the canyon of the Arkansas, above the junction with Tennessee creek, is a gneiss which has very close affinities 

to the granites usually called eruptives. It passes gradually into a 

micaceous schist. On Trout creek is syenite and granite, which gradually assumes a gneissoid structure and contains fragments of gneiss 

from 6 to 20 inches in diameter which are fraginental in shape. Their 

presence is difficult to account for. If the granite is eruptive these 

might be included fragments, but there is no reason to assign any such 

origin to it, for its gradual passage into the gneiss is easily traced. On
312 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 88.

Currant creek, at the west side of South park, near mount Lincoln, at 

Idaho springs, on the east side of South park, massive granite or syenite is seen grading into gneiss and mica-schist. At Chicago creek 

coarsely crystalline granite is sharply separated from the adjacent 

gneiss, the junction being as sharp as between a trap dike and adjoining rock. Some of the porphyritic rocks, granites and syenites are 

placed among the eruptives. This is done in deference to commonly 

received opinion; but as there is no locality in which these rocks do 

not pass imperceptibly into gneiss, the conclusion is reached that the 

preponderance of evidence is in favor of their rnetamorphic origin.

In speaking of Colorado metamorphic rocks in general it is said 

the prevailing rock is a micaceous schist passing into gneiss, and containing much granite, which in some localities entirely replaces the 

others. Not unfrequently the mica-schist is displaced gradually by hornblende-schist, which becomes a hornblende-gneiss, containing masses 

or strings of syenite, as the other form contains ordinary granite. 

Slates are almost wanting, and thick strata of quartzite belonging to 

this series were observed at only two or three localities. Serpentine 

and limestone seem to be absent altogether. It is impossible in the 

present state of our knowledge to come to any definite conclusion respecting the relations of these rocks. Hayden, in one of his reports, 

has referred them with doubt to the Laurentian. To determine this 

matter careful investigation at the north, is still needed.

KING,7 in 1878, states that in the Colorado range are two series which 

are probably unconforma,ble. The upper group is distinctly bedded, 

has a variable amount of mica, and is correlated with the upper horizons of the Medicine bow and the higher members of the Park range, 

Eed creek in the Uinta, the Wasatch and Salt lake islands, and the

exposures in the Humboldt mountains, Franklin buttes, and Kinsley 

district. In the Clear creek region the series is not less than 25,000 

feet thick.

EMMONS, (S. F.),45 in 1890, states that Cross has discovered in the hills 

east of the Arkansas river, at Salida, a thickness of about 10,000 feet of 

slates and "schists entirely distinct from the Archean and probably 

unconformable with it. These are referred to the Algonkian.

LAKES,46 in 1890, made observations upon the district of South Boulder, Coal and Ealston creeks. In the South Boulder and Coal creek 

area were found between the Trias and the heavily bedded gneisses a 

series of quartzites, schists and conglomerates the clastic character of 

which is unmistakable. The series has been subjected to intense dynamic action, so that the pebbles of the conglomerate are elongated, and 

if it were not for the bands of this material it would be difficult to show 

that the series was an original clastic one, as the finer grained rocks are 

completely crystalline quartz-schists and mica-schists. The dip of the 

series is at a high angle away from the main mass of the mountains. Its 

higher members are quartzite, and pass down into mica-schists and
VAN HIM.] THE CORDILLERAS. 313

quartz-schists, which are interstratified with beds of conglomerate. 

In passing downward the mica-schists become interlaminated with 

gneiss, which becomes more and more abundant, and upon Coal creek 

cutting the schists are also pegmatitic granite veins. No where between 

the clastic and gneissoid series was any discordance discovered, there 

appearing to be between them a gradation, although a somewhat rapid 

one. The clastic series at South Boulder creek is at least 1,000 feet 

thick. The lower gneissoid series at times is in part quite regularly 

laminated, at other times becomes a heavily bedded granite-gneiss, but 

for several miles toward the core of the mountains, as far as investigated, does not become structureless granite.

On Coal creek, at one place within the clastic series, is a wedge of 

granite of considerable thickness, and this does not grade into the

clastic rocks as does the main granitoid gneiss area, The relations of

the Trias both to the granite-gneiss and to the clastic series are such 

as to show that it is clearly a later formation separated from them by 

a very great unconformity.

At Ralston creek the heavily bedded gneisses, were found to vary 

into hornblende-gneiss interlaminated with granite veins, and these 

into rather fine grained schistose rock, but there was discovered here no 

clear evidence of a clastic series, although the more schistose phases 

immediately under the Trias may represent the more altered clastic 

schists of Coal and South Boulder creeks.

LITERATURE OP THE WET AND SANGRE DE CRISTO MOUNTAINS.

SCHiEL,38 in 1885, describes the predominating rock of the Sangre de 

Cristo valley as a feldspathic granite, passing gradually into a gneiss 

on the right bank of the creek, the gneiss supporting a hard, shaly 

sandstone and a bluish brittle limestone.

ENDLICH,43 in 1874, describes the region south of the Arkansas as 

consisting chiefly of granite. That forming the Sangre de Cristo 

mountains is of different character and appearance from that of the 

Front range. The Wet mountains are regarded as eruptive. Gneiss 

occurs in this range at Hunts peak and from there 6 or 7 miles to the 

northwest, and is regarded as metamorphic, although it weathers more 

like granite than a stratified rock. From the granite axis of the 

Sangre de Cristo the sedimentary rocks dip away both to the east and 

west. The eruptive granite of the Sangre de Cristo is the youngest of 

the region. Although the Sangre de Cristo range is spoken of as eruptive, this is not considered to be so in the same sense that basalt is eruptive, but to imply that the granite by some vertically acting force hdfe 

been thrown upward and may now be in contact with strata which were 

once above it.

CoPE,47 in 1.875, states that in the Sangrede Cristo mountains is stratified granite, which is either heavily bedded feldspathic porphyry or 

finely bedded hornblende-gneiss.
314 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

ENDLICH,48 in 1877, states that inetamorphics compose the main bulk 

of the interior portion of the lower Sangre de Cristo range, though at 

many places sedimentary beds and volcanic flows have obscured the 

relations. The highest peaks of the range are as a rule metamorphics 

among which granites and gneisses are predominant. These are associated with granites and gneissoid-schists, associated with which are 

hornblendic, chloritic, and micaceous schists. Near Triuchera the sedimentary strata stand nearly on end and lie tipped up against the 

granite. At other places the granite protrudes through the Carboniferous. It is concluded that the metamorphics of the lower Sa.ngre de Cristo 

are altered Silurian rocks. North of the Arkansas river the Silurian 

formation occurs. From here it crosses the river toward the south and 

is last seen as such near the northern end of the Sangre de Cristo range. 

In its stratigraphical relations it is conformable with the overlying 

younger formations wherever it has been there seen.

ENDLICH,49 in 1878, states that while in the Saugre de Cristo the 

eruptive granite is the cause of the upthrow of the Carboniferous strata, 

nowhere in the sedimentary beds is found any case of intrusion. These 

granites are regarded as post-Carboniferous.

EMMONS, 45 (S. F.), in 1890, states that quartzites have been noticed connected with the Archean of the southern end of the Sangre de Cristo 

range which maybe assumed to be the remnants of some Algonkian beds.

LITERATURE OF THE FRONT RANGE OF SOUTHERN COLORADO AND NORTHERN

NKW MEXICO.

WiSLTZENUS,50 in 1848, states that granitic rocks prevail in the 

mountains about Santa Fe, and for some distance to the south. These 

are associated with porphyry and trap.

BLAKE,51 in 1856, describes ridges of metamorphic slate in the Santa 

Fe mountains, upon the edges of which rest horizontal Carboniferous 

strata.

LoEW,52 in 1875, states that the mountains between Santa Fe and Las 

Vegas contain Azoic rocks which are chiefly granite and syenite. At 

Santa Fe creek gneiss is accompanied by primitive clay-slate and 

syenite. Veins of fine grained gneisses occur in a coarse aplite or 

granulite also intersected by syenite seams.

ST. JOHN,53 in 1876, describes the Black mountains as a lofty granite 

barrier. The upper canyon of the Ciinairon is composed of granitic 

rocks, with which are associated micaceous schists and hard quartzose 

rocks. In the Raton hills are granitic igneous rocks, the relations of 

which to the Tertiary are not easy to make out. The Yermejo mountains have a nucleus of massive metamorphic rocks.

DEWBERRY,54 in 1876, states that in the Santa Fe mountains is found 

coarse red granite, characteristic of the central portion of the Eocky 

mountain system. It differs from the granite of the Appalachian as 

well as those of the Sierra and Cascade. The Carboniferous strata 

rest directly upon the granites. The central axis of the Nacimiento
VANHISB.] THE CORDILLERAS. 315

mountain is composed of a similar massive red granite, upon the slopes 

of which rests the Carboniferous formation, for the most part limestone, 

in many places nearly vertical yet but slightly.metamorphosed.

STEVENSON,55 in 1879, describes a continuous Archean area on the 

western side of the district running from Spanish peaks south. It forms 

the axis of the Culebra range, continues through theTaos andtheMora 

ranges, and passes into the Cimarron range. The Santa Fe and United 

States anticlines show Archean rocks which are separated from the 

main area. The rocks show great uniformity in character, including 

gneissoid granite, gneiss, and mica-schist as the predominant types.

STEVENSON,56 in 1881, gives a systematic account of the Archean 

rocks of southern Colorado and northern IsTew Mexico. Four areas are 

seen within the district. The most western marks the course of the 

Santa Fe axisj the second, that of the Culebra-Mora axis, and the 

third and fourth that of the Cimarron axis. The rocks in the Santa Fe 

axis are gneiss, mica-schist, which resembles sandstones, and granite. 

South of the Santa Fe road are frequent exposures of an exceedingly 

coarse granite, which resembles a metamorphosed conglomerate, the 

pebbles being thoroughly distinct. With this are many beds of almost 

black gneiss, holding beds of snow-white quartz. The Culebra-Mora 

axis varies in width from 5 to 25 miles. It includes granite, gneissoid 

granite, micaceous and hornblendic schists, and quartzites. Compact 

gneiss, quartzite-like in character, is found in the main canyon of Costilla creek. Bands of quartzites are found on Comanche creek, the 

north fork of Moreno creek, in Costilla creek range on Coyote creek, 

and in the vicinity of Santo Mno on the Cebolla creek. These are 

sometimes found in gneissoid-granite and sometimes in mica-schist. The 

granite below the junction of the forks of Moreno creek is very coarse 

and resembles conglomerate. The rocks of the Cimarron axis include 

mica-schist, coarse granite, and gneiss sometimes resembling quartzite. 

The dips of the Archean rocks are much confused and the distortion at 

most localities is so great that neither the succession of the strata nor 

the general structure could be made out during the brief examinations. 

Positive proof of nonconformability to the overlying Carboniferous is not 

easily obtained, the main obstacle in the way of making the determination being the character of the rock. Usually the disturbance near 

the junction of the two series is very violent and the rate of dip changes 

greatly within a short distance, sometimes becoming even reversed. 

But distinct nonconformability may be asserted as existing in the vicinity of Costilla peak, where the enormously thick Carboniferous series 

terminates abruptly against the Archean core of the Cimarron axis. 

No absolute evidence exists to settle the age of these rocks. Lithologically, they bear a close resemblance to the Laurentian series of the east, 

and at more northern exposures within the Rocky mountain region they 

have been referred by all observers to that age. The coarse gneissoid 

and often conglomerate granite immediately underlying the Carboniferous at many localities may possibly be of somewhat later origin.
316 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

LITERATURE OF THE PARK RANGE.

MARVINE,41 in 1874, describes the northern part of the Park range 

as composed of a very distinctively and evenly bedded series of schists, 

gneisses and granites, which have a strike nearly with the ridge, and 

a dip of 40° or 50° to the southward.

LITERATURE OK THE SAWATCH MOUNTAINS.

HAYDEN,57 in 1874, describes the Sawatch range as a solid mass of 

granite, 80 miles in length by 40 in width, which has acted as a single wedge thrust upward, and thus causing the sedirnentaries to incline 

from either side.

PEALE,42 in 1874, states that on Massive mountain the rocks are 

mainly gneissic, with alternations of porphyritic granite or graniteporphyry, with seams of quartzite and hornblendic volcanic rock. On 

Eagle river, at the base of the section is gneiss, and above this is white 

quartzite.

. BNDLIOH,43 in 1874, states that the granite of the Sawatch on the 

west side of the Arkansas is probably post-Silurian. This range has 

two kinds of granite that are peculiar to it and an older predominating 

one. Both of these are newer than the red, middle, and coarse grained 

rock found in the Wet mountains. The first of these varieties composes 

the main part of the range and constitutes its most prominent peak, 

mount Princeton. Besides this, there is protogine and eruptive granite. 

Mount Ouray is composed in large part of- hornblende rock. On one 

side the hornblende and granite are mterstratified, the granite being 

regarded as intruded between the strata. The change from the granite 

to the hornblende rock is always abrupt.

ENDLICH,48 in 1877, states that at the southern end of the Sawatch

range trachyte is the principal rock.

EMMONS, (S. F.),58 in 1882, states that in the Mosquito range are found 

granites, gneisses and amphibolites. The granites are in most cases 

stratified and are of undoubted sedimentary origin. In other cases 

the evidence is less clear and they have the characteristics of eruptive 

granites. Within the masses of the normal granite occur large irregular vein-like masses of secondary origin, corresponding to pegmatite. 

The gneiss is mostly mica-gneiss. The anrphibolite is less abundant 

than the gneiss and granite and occurs interstratified with them. Unconformably above these are quartzites which bear Primordial fossils 

belonging to the Potsdam.

LAKES,59 in 1886, describes the Sawatch. range as consisting of gneiss 

and granite penetrated by volcanic dikes, with patches of Silurian, 

Carboniferous and more *recent strata resting on or uptilted against 

each flank. In the Aspen region are two granites, one the metamorphic granite of the Sawatch and the other a diorite and eruptive 

lava of the Elk mountain system. On the granites are unconformably 

located the Cambrian strata, the base of which is quartzite.
VAN HUB.] THE CORDILLERAS. 317

LITERATURE OF THE ELK MOUNTAINS.

EAYDEN,57 in 1874, describes the Elk mountains as composed of an 

upthrust of igneous granite, which carries portions of the sedimentary 

beds on its summits or tilting away from the sides at various angles. 

The lowest group of sedimentary rocks is Lower Silurian. In some 

cases there is complete overturn of immense groups of beds, so that 

for several miles there is a double series from the Silurian up to the 

Cretaceous, inclusive, as at the head of East river and near Snow 

Mass peak.- Northeast of Snow Mass the sedimentary beds may be 

seen resting on the granite, on these a great thickness of red beds, 

and on the top of the latter masses of irregular thickness of eruptive granite from 100 to 400 feet thick, and at both ends the red beds 

again resting upon the eruptive mass, so that the granite now appears 

like an interstratined rock. Gothic mountain and Crested butte are

regarded as immense dikes, the melted matter being pushed up through, 

the superincumbent matter so as not to disturb to any great extent the 

thickness of yielding Cretaceous shales and clays. On Eagle river are 

beds of sandstones and quartzites, the fragments of which indicate 

that they have been derived from gneissic and granitic rocks.

PEALE,42 in 1874, describes the entire mass of granite of the Elk 

mountains as having been either in a plastic or melted condition. The 

elevation of the range was post-Cretaceous. The mountains are cut 

by numerous dikes, which are in pa.rt trachytic, but which are, however, believed to be connected with the eruptive granite. On the southeast side of Elk mountains are chloritic schists, quartzites, and sandstones, all very much metamorphosed.

HOLMES,60 in 1876, gives the geology of the northwestern portion of 

the Elk range and describes in detail the character of the folding, faulting and relations of the crystallines to the sedimentary rocks. On the 

east side the sedimentary strata lie up against the granite of the Sawatch 

range, and on the west they have been carried high up 011 the arch of 

the Elk mountains, leaving the synclinal depression between the ranges. 

The axes of the two ranges are not parallel, but approach each other 

toward the south and separate toward the north, giving an included 

angle of some 30°. In the vicinity of Italian peak the granites of the 

two ranges are in contact, or nearly so, being totally distinct in appearance and in reality. The sedimentary beds of Sopris and Bock creeks 

show a considerable amount of nietarnorphism and lateral crushing, 

the Dakota sandstones of the latter being changed to hard, flinty 

quartzites. A great fault, combined with a fold, runs from the north 

part of the Elk group, i. e., Snow Mass mountains, to its south part, 

White Eock mountains. In the sections the granitic rocks are represented in places as being above the sedimentary and in other places as 

intruding themselves among the layers.

LAKES,61 in 1885, describes the stratified rocks adjacent to the Elk 

mountains as riddled with dikes and baked and metamorphosed in
318 PRE-CAMBEIAN EOCKS OF NOETH AMEEICA. [BULL. 86.

places almost past recognition. The huge volcanic masses are some 

of them dikes, while others may be laccolites.

LAKES,59 in 1886, describes the Elk mountain eruptions as having 

occurred under an enormous pressure of superincumbent strata not less 

than 10,000 feet thick. The Elk mountains are diorite instead of being 

eruptive granite as called in Hayden's reports.

LITERATURE OF THE GRAND AND GUNNISON RIVERS.

SCHDBL,38 in 1855, states that along Coochetopa creek and Grand 

river valleys are granite, gneiss, shale and mica-slate.

PEALE,42 in 1874, states that adjacent to the Gunnison a section has 

at its base rust-colored granite, above which is mica-shist, and over 

this quartzite and sandstone.

STEVENSON,44 in 1875, states that at several localities along the 

Grand and Gunnison is a peculiar, regularly laminated gneiss which 

resembles a micaceous sandstone. It always occurs directly under the 

sedimentary rocks and no similar formation occurs lower down. It is 

clearly uncou form able to the great mass of schist and gneiss, though 

precisely like them in its changes. In consideration of all the circumstances, one can not resist the temptation of regarding it as belonging 

to a later series.

PEALE,e2 in 1876, describes Archean rocks as occurring along and 

near the gorges of Eagle and Gunnison rivers. The rocks of the Eagle 

river are known to be pre-Potsdam, because at the head of the stream 

such rocks rest upon them. On the Gunnisou river the Archean rocks 

are gneisses and schists. The presence of Dakota beds here resting 

upon the Archean is supposed to prove that in pre-Cretaceous times 

this area was above sea level.

PEALE,63 in 1877, describes the Archean rocks of the Grand river.

These occur in limited areas throughout the district between parallels 

37° 52' and 39° 15' and meridians 107° and 109° 30'. They are generally confined to the courses of streams flowing in canyons. In many 

places the schistose character is very distinct and the bedding clearly 

seen, but in most cases no traces of bedding were seen, the rocks being 

granitoid. From the number of exposures noticed it is evident that 

the rocks underlie the entire district, although from the limited and 

isolated exposures it was not possible to trace connections from one 

place to another. The oldest sedimentary beds resting upon these 

rocks are Carboniferous or pre-Carboniferous, showing that they are 

at least pre-Carboniferous, but it is believed that they are preSilurian. Along the Gunnison outcrops of quartzitic layers occur 

with softer red and gray gneissic layers. On the Little Dolores are 

mica-schists and quartzites dipping northeast at angles of 60° to 70°. 

As to the origin of these rocks it is said: They were once deposited as 

sediments. Whence were their materials derived? We have no data 

from which we are able even to guess what was the extent of the Ar-
VANHISB.] THE CORDILLERAS. 319

chean continent, or what its character was. From the fact that in the 

Grand Canyon of the Colorado similar rocks are found below the Potsdam, and from the profundity of their metamorphism it is believed that 

these crystalline rocks are Archean.

LITERATURE OF THE QUARTZITE MOUNTAINS.

BNDLICH,64 in 1876, describes the Quartzite mountains. Near the 

northern border and toward the middle, quartzites and schists predominate, while granite appears toward the east and south. The 

quartzites are mostly of a white or gray color, gradually becoming filled 

with mica or chlorite, thus turning into schists. The relations of the 

quartzites are extremely varied and complicated. Granites change 

into quartzites between stations 21 and 22. The schists have a less 

horizontal extent but are just as distinct as the quartzites. They also 

show great variations in strike and dip. As a rule they seem to be 

older than the granite, but it was not possible to establish this point 

beyond doubt. The schists were nowhere found except in the quartzite group. All the granite shows a remarkable regular stratification, 

not an apparent one only, produced by the main cleavage plane of the 

feldspar or mica lying in one direction. The dip of the strata is conformable with those of the quartzites and schists and away from the 

anticlinal axis toward the south. Generally the dip is not very marked 

but still reaching from 7° to 10°. All along the Animas the junction 

of the sedimentaries with the granite was not observed. The latter 

was exposed in the valley, while the former appeared in steep bluffs on 

both sides. From the dips observed it became evident that the two 

were conformable.

As to the origin of the metamorphic group of rocks it is said that 

the Devonian strata wore deposited on the granitic strata conformably. 

Also that from the quartzite into granite the transition is perfect, 

although often small specimens can be found showing on the one side 

granite and on the other granular red quartzite. Near the top of a 

bluff the latter is white or yellowish, becoming red and brown lower 

down. Finally some mica is observed in it, and the feldspar appears 

as such, until the coarse grained granite is reached. The metamorphosis is very thorough, and can be admirably studied at this point, 

go far as could be decided, the granite was formed out of a partly argillaceous sandstone, containing some iron in an oxidized state, while the 

purer sandstones were turned into quartzites. Probably the process of 

metamorphosis was a very slow one, and lasted a long time. Throughout the stratification is well preserved in all the rocks of that group, 

but particularly so in the granite of the locality just described. Even 

the thicknesses of the various strata which have been altered into 

granite correspond approximately to those at present exhibited by the 

superincumbent beds. At a short distance north of station 48, the 

granite overlies the dark schists, which in turn seem to be younger
320 PEE-CAMBEIAN KOCKS OF NOETH AMEEICA. [BULL. 86.

than the true quartzites forming the main bulk of the mountains still 

farther north. Taking into consideration, therefore, the observed conformity of the underlying metamorphics with the overlying sediinentaries; taking into consideration, furthermore, the analogous character 

of stratigraphical relations, the conclusion must be reached that those 

sedimentary beds, which existed below the Devonian, furnished the 

material for the metamorphic masses.

CoMSTOCK,65 in 1883, states that in San Juan county there are no 

rocks which are of Archean age. The granitic and quartzitic series of 

the Animas river are regarded as metamorphic and said to be of Upper 

Silurian or Devonian age.

CoMSTOCK,66 in 1887, describes the metamorphic series in southwestern Colorado as probably Silurian or Devonian. This series is susceptible of division into an upper or granitic division and an underlying 

quartzitic formation. The quartzitic group is exposed in the Animas 

canyon below Silverton, forming a line of jagged peaks to the eastward, 

the Needle mountains. Whenever the quartzite is well uncovered the 

more recent granites are usually traceable along the flanks of the belt. 

The geological map brings out no apparent system in the metamorphic 

rocks.

LAKES,67 in 1889, describes on the Mears road, south of Ouray, as 

succeeding the Carboniferous limestone, a thickness of 13,000 feet of distinctly stratified and hard vitreous quartzites, slates and schists. Part 

of these may belong to the Silurian and Cambrian, but as these combined rarely attain in Colorado a thickness of 1,000 feet, so great a 

body is extraordinary and suggests that the lower part of it may, as in 

Canada, belong to the Huronian or Laurentian, upper divisions of the 

Archean not elsewhere represented in Colorado. The dip of the quartzite is about 75° to the north. The uplifted crests have been deeply 

eroded and iu the hollows SO formed rest the massive volcanic breccias.

EMMONS, (S. F.),45 inlS90, states that on the north slope of the San Juan 

mountains, near Ouray, is over 10,000 feet of closely folded quartzites, 

conglomerates, and slates of the pre-Cainbrian age, and it is believed 

that the quartzite peaks in the southern portion of this region are 

probably composed of the same series of rocks. These are referred to 

the Algonkian.

VAN HiSE,9 in 1889, made observations along the Animas, the railroad being followed from below Keedleton to Silverton, a distance 

of about 17 or 18 miles. As mapped by Endlich on Sheet XV of the 

atlas of Colorado, this course is situated, with the exception of 5 or 6 

miles, in the quartzite area. Quartzites occur for a little more than 2 

miles in the vicinity of Elk park in the middle of the area mapped as 

quartzite. The granitic area was found to be a most intricate complex 

of massive granite, coarse and fine, white and black banded gneiss, and 

black hornblende-schist or gneiss in dike-like forms. The strikes and 

dips vary greatly, although for the most part they are high, running
VANHJSE.J THE CORDILLEEAS. 321

from 75° to 85°. At one place the dip of the schistose structure was 

observed to be as flat as 10° or 15°.

The quartzitic area is in places conglomeratic. The rock is for the 

most part a rather pure white or gray vitreous quartzite, although occasionally it shows more or less of a slaty appearance. Nowhere in 

the quartzite was found any hornblende-schist in dike-like forms such 

as occur in the granite, or any layers which could possibly be mistaken 

for the black or white gneissoid phases of rock which occur so 

abundantly in the granite area and have such intricate relations with 

the granite. The dips of the quartzites are also for the most part high, 

being from 60° to 70°. In the quartzites, as in the granites, there are 

great local variations in the strike and dip of the rock. Upon both 

sides of the quartzite area where the change to granite occurs no evidence whatever was seen of a transition between the two classes of 

rocks. In neither were the quartzites and granites in contact; they 

were found however, a few paces apart. At the southern boundary, 

while the two rocks were not actually found in contact, there is a 

marked discordance in the strike and dip of the schistose structure of 

the granite and of a series of sharply folded anticlines and synclines 

of quartzites which are adjacent to the granite.

What is said by Endlich as to the sharp contrast between the sedirnentaries and granite may mean the contrast between the black hornblende-schists and gneisses with the coarse granitoid gneisses and 

granites. If this is the case, the statement is true, for these materials 

are seen in sharp contact at very numerous places along the Animas. 

If these hornblende-schists and gneisses are altered eruptives, as they 

appear to be, the sharp contacts would have no bearing upon the inetamorphic origin of the granite.

Some of the quartzites have a color similar to the coarse reddish or 

grayish gneisses, and also show to some extent a banded appearance1 . 

It may be that this fact has led to the statement that there is a transition between them and the granitic rocks.

A study of numerous thin sections of the material collected shows 

that the rocks composing the area here called granitic are always 

completely crystalline, giving in the thin section no evidence whatever 

of clastic characters; on the other hand, all the rocks belonging in the 

quartzite area, while locally considerably altered by dynamic action, 

show very clearly their clastic character. However, the evidence of the 

microscope is not necessary to show the clastic origin of these quartzites, as the conglomeratic phases seen in the field are sufficient to 

demonstrate this.

As to the conformability described by Endlich between the flat-lying 

Devonian and these crystalline rocks, no observations were made. It 

is, however, to be remarked that Endlich states that the crystallines 

are flat-lying, having a dip of not more than 10° to 15°. This was 

observed to be the case in one locality, but as before said, the great 

Bull. 86 21
322 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

number of observations along the Animas show the dips to be for the 

most part very high, i. e., from 60° to vertically, and in various directions. All of the evidence as to the strike and dip show that the area 

of quartzites and granites is one in which the folding is very complicated.

Bearing upon the question of the position of the quartzitic series 

with reference to the fossiliferous rocks is the occurrence south of 

Ouray. along Bed mountain creek and one of the branches of the TJiicompahgre, of a great series of slates, quartzites and conglomerates, 

with high dips and repeated by folding, which are in lithological character identical with the quartzites south of Silverton. Just south of 

Ouray the red beds of the Jura-Trias are found in almost horizontal 

position upon the upturned edges of the slates and quartzites. This 

unconformity, in the distance at which it may be observed and in 

the masses of rocks exposed, is remarkably handsome. Conformable 

below the red beds of the Jura-Trias, at Ouray, the Carboniferous 

rocks appear, but they were not seen in contact with the slates 

and quartzites. That the quartzite series was an old shore against 

which the Carboniferous and Jura-Trias were deposited can not be 

doubted. In the distance of about 5 miles in which this quartzite 

series is exposed a slate band is found five times. In going north the 

dips are first south and then change to the north, in which position 

they continue until the Carboniferous appears. All this suggests that 

we have here to deal with a folded series and not one necessarily of 

very great thickness, although probably several thousand feet thick. 

As Ouray is only a few miles from Silverton, the argument of analogy 

makes it probable that the similar plainly fragmental slates and quartzites south of Ouray are the equivalent of the quartzites of Elk park. 

The facts bear against the probability of a transition from the Devonian 

into the quartzitic series of the latter place. The one occurrence in 

which this transition is definitely asserted is perhaps a case of a reeomposed rock resting upon a crystalline one. Similar occurrences have 

often been described.

As to the relations of the granitic area to the quartzites along the 

Animas, there is no clear evidence. The fact that the granitic area 

is an intricate complex of regularly banded gneisses, of granitoid 

gneiss, and of granites cut by hornblende-schists in dike-like forms, 

combined with the fact that no such dike-like areas are found near 

the quartzites, seems to indicate that the quartzite is of later age than 

this complex. This probability is still further strengthened by the 

completely crystalline character of one series and the plainly fragmental character of the other. This point would have little weight if 

the granitic area was a simple massive rock which might be the result 

of a single eruption. But the varieties of rock of which it is composed 

and the intricate way in which these lithological phases are mingled 

indicate that the history of the granite area is a most complex and
VANHISE.] ^ THE CORDILLERAS. 323

/ long-continued one, and was far advanced before the deposition of 

the fragmental rocks. If it should be held that this granitic area is 

eruptive as a whole and later than the quartzite, the question arises, 

Why is it that nowhere do any of the rocks which belong in it cut the 

quartzites? If, on the other hand, it is maintained that it is metamorphic in origin, the question arises, Why is it that all parts of it have become so completely crystalline while the quartzite is still so near its 

original condition?

LITERATURE OF THE LA PLATA MOUNTAINS.

HOLMES,68 in 1877, places the La Plata mountains in the metamorphic 

belt because the central portion, as exposed in the deep-cut valley of the 

La Plata river, is composed of uplifted and altered sedimentary rocks; 

but there are associated with these a very considerable area of eruptive 

rocks with a resulting great complication of structure. This metamorphic group seems to be a prolongation to that to the northeastward 

about the Animas. Against attributing any great amount of change 

in the sedimentary rocks to the presence of the trachyte is the fact that 

in the neighboring groups of mountains of trachytic origin there is little or no metamorphism apparent. In the central part of the altered 

area the metamorphic mass proper extends up to and includes the red 

.beds. As one of the best examples of the metamorphism may be mentioned that on the west face of the first mountain south of Hesperus. 

Here a mass of metamorphic shales abuts or is welded to the trachyte 

face of the mountain. The exact point of contac^can not be determined, 

as the metamorphism has been so complete that the shales seem to 

change gradually into trachyte. Away from the trachyte they gradually assume the appearance of a massive grayish yellow quartzite, and 

in a mile or more from the place of contact assume a shaly character 

and dark color.

ENDLiCH,49 in 1878, gives a general discussion of the formations of 

Colorado. In preference to the word Azoic the word Prozoic is used. 

Belonging to this gropp, in southern Colorado, is an extensive series 

comprising gneisses, granites, various schists and diorites. Of these 

the first named appear to be the oldest, as may be inferred from the 

relations to the granites more particularly. The schists are in subordinate quantity. It often is a matter of difficulty to discriminate between the Prozoic and the next group of metamorphic rocks. This 

latter is the most varied and enormous in its development. Large 

areas are covered by rocks of this group, which occur in almost endless variety. IH several instances localities may be observed where the 

transition from undoubted sedimentary into metamorphic beds is evident. This, however, must be considered as an exception rather than 

the rule. The gneiss is the oldest of the metamorphic rocks in the district examined. Micaceous, hornblendic and chloritic schists occur as 

such associated with other metamorphic rocks. Frequently they are
324 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

due to the substitution of minerals within the gneiss, but they are also 

found totally independent thereof. If a suggestion may be offered 

which, however, can not at present be proved, the author would say 

that argillaceous sandstones form granite. With the decrease or increase of argillaceous matter in the sandstone the quantity of feldspar 

in the granite stands in direct proportion. Siliceous sandstones form 

quartzites. Shales, arenaceous in part, are changed into gneisses, and 

if the quartz in them is predominant they turn into schists. Quartzites 

can not be generally classed with the metamorphic rocks, but in the 

Quartzite mountains a complete alteration of the original sandstone 

has taken place, although stratification has been retained in a measure. 

Granite is the most representative species of the metamorphic group. 

It is younger generally than the schistose rocks occurring with or near 

it. In the Qiiartzite mountains there is a direct transition from sedimentary beds into typical granite. A large part of the granites in 

southern Colorado is regarded as metamorphosed Silurian, Devonian, 

and in rare instances even Carboniferous strata.

SUMMARY OF RESULTS.

The greater parts of the Front, Wet, Sawatch, Park, and Quartzite 

ranges and the crystalline rocks of the Gunnison and Grand are a 

completely crystalline complex of rocks which are certainly pre-Cambrian; for, resting upon these ranges unconformably and bearing de"- 

bris from the older series are the fossiliferous Cambrian. These contacts are found both on the east side of the Front range and in the 

parks along the Sawatch, as well as at Eagle river in the Gunnison and 

Grand region. The granite-gneiss-schist complex of the Quartzite 

mountains also without much question belongs in the same position.

The relations, so excellently described by Marvine and Stevenson, 

between the nearly structureless granites constituting the core of the 

ranges and the well laminated Schists and gneisses are those between 

the granites and associated crystallines described in Massachusetts by 

the elder Hitchcock in 1860, by King along the fortieth parallel, by 

Lawson about the Eainy lake and the lake of the Woods, and by Winchell in northeastern Minnesota. That is, in passing from a schistose 

to a granitic area the finely laminated schists become coarser and 

coarser; then appear thin belts of gneiss, which become more and more 

prominent until the rock has changed to a gneiss, and this by imperceptible stages passes into a granitoid gneiss, then into a granite. A 

whole or a part only of the laminated rocks may be cut by granite veins, 

while oftentimes there are considerable masses of granite in the schists 

of the same character as the main granite mass, the contacts being exceedingly sharp. In a few cases in the massive granites are found 

fragment-like areas of the schists. These imperfectly summarized relations are regarded by Stevenson, Marvine, and the other writers to 

be evidences of the metamorphic character of the whole series, while
VANHISB.] THE CORDILLERAS, 325

«2

the intrusives are regarded simply as parts of the main mass which 

have become perfectly fluid and therefore locally take on eruptive 

forms. Lawson declines to carry the term metamorphic over to the 

plastic material and speaks of it as a subcrustal magma. As the real 

character of such granite-gneiss-schist complexes is a question which 

concerns not only the Colorado ranges, but almost every other preCambrian region of North America, the discussion of this question is 

deferred for the general chapter. It is, however, plain that in the mountain ranges of Colorado is a thoroughly crystalline, intricate, fundamental complex like tha"t found in most of the pre-Cambrian areas 

already considered.

Besides these crystallines there are at least two areas in which unmistakable pre-Cambrian elastics are present. These are the districts of 

Big and Little Thompson, South Boulder, Coal and Ralston creeks in 

the Front range, and the district of the Quartzite mountains in the San 

Juan region. It is also probable that the quartzites and mica-schists 

of northern New Mexico, described by Stevenson, is a third series, 

although the relations of these beds to the other rocks are not indicated. 

The great beds of white quartzite and the granite-conglomerate in the 

neighborhood of Santa Fe strongly suggests that here is a clastic series, 

the granite-conglomerate probably being a recoinposedrock. A fourth 

great series which possibly falls among the pre-Carnbrian elastics is 

that seen by Gross in the neighborhood of Salida.

In the Front range the descriptions of Marvine and Lakes agree that 

there is an apparent gradation from the clastic quartzite and mica-schist 

series to the gneisses and gneissoid granites, although Lakes states 

that the transition is somewhat abrupt. Two explanations may be applied here: First, there may be a real physical break which has not 

been detected between the elastics and the crystallines. In favor of this 

hypothesis is the fact that quartzites are found nowhere else in the vast 

area of the Front range, and that nowhere else are there any rocks which 

are even described as having any evidence of fragmental character, unr 

less foliation be taken as such evidence. ' If this clastic series and the 

great complex of granite, gneiss and schist are of the same origin and 

age, it is certainly strange that nowhere except in this very restricted 

area do beds of quartzite or quartz-schist occur. Also the presence of 

genuine granitic pebbles in the conglomerates at least shows that there 

existed an earlier granite from which de'bris was derived. Second, those 

who believe that the fine-grained gneisses, completely crystalline schists 

and granites are all really of eruptive origin, the foliation being but 

evidence of powerful dynamic action, will probably maintain that this 

clastic series is the more ancient one and has been cut and metamorphosed 

by the intrusion of the igneous rocks.

In the Quartzite mountains the evidence that the fragmental slate 

and quartzite series is more recent than the granite-gneiss-schist complex is far more weighty. Here an intricate complex of irregularly i
326 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

banded gneisses, granitoid gneisses and granites are cut by foliated 

dikes of hornblende-schist, which never penetrate the fraginental 

series. At one of the places along the Animas at which the quartzite is separated by a very short interval from the granite complex there 

is a sharp discordance in its foliation and a series of sharply folded 

anticlines and synclines of quartzite, which with considerable certainty 

indicate the bedding of the latter group. Also, while the quartzite 

series inclines at a steep angle and is in places sharply folded, it upon 

the whole has not suffered any such profound and repeated dynamic 

movements as are exhibited by the granite-gneiss complex. If the latter series be taken as sedimentary its complete metamorphism argues 

its greater age; and if it be taken as wholly eruptive its present implicated character, with strongly developed schistose structures, denoting profound metamorphism, indicates a history much longer than 

the one revealed by the quartzites. This great quartzite and slate 

series can then with a considerable degree of certainty be regarded as 

much later in age than the granite-gneiss-schist complex. Also it is 

far more ancient than the Carbonifef ous, because near Ouray the Trias 

conformably above the Carboniferous rests in a nearly horizontal position upon the upturned, nearly vertical, truncated edges of the quartzite. On general structural and lithological grounds it may with great 

probability be referred to the Algonkian. Of the two other areas of 

clastic rocks too little is known to offer any suggestions as to their age 

or relations.

A part of the so-called granite (diorite?) of the Elk mountains and a 

part of that of the Sangre de Cristo range is plainly an eruptive of later 

age than the Cambrian, and therefore it does not properly fall withiii 

the province of this review.

Whether there are any pre-Canibrian rocks in the La Plata mountains 

is uncertain. The small area of metamorphosed rock bears suchrelations 

to the eruptives as to suggest that their present condition may be due 

to contact metamorphism.

SECTION VII. ARIZONA AND WESTERN NEW MEXICO.

LITERATURE.

PoWELL,28 in 1874, states that below the Carboniferous is a succession of nonconformable shales, sandstones and limestones, the greatest 

thickness of the beds being a little more than 10,000 feet. The beds 

are traversed by dikes of trap or greenstone and irregular layers of 

the same eruptive material are found in places between these nonconformable rocks and the overlying beds of Carboniferous age. Provisionally these sedimentary rocks are called Devonian, and Silurian. 

Still underlying these is an extensive series of metamorphic crystalline 

schists, in some places yet showing faint traces of the original stratification3 but usually these are so degraded that the total thickness of the
U.S.GEOLOGICAL SURVEY. 

; 37r

UNCLASSIFIED PRE-CAMB. ALGONKIAN 

GEOLOGICAL MAP OF ARIZONA AND PAR

SHOWING PRE-CAMBRIAN ROCKS

Compiled from the Wheeler and Dutton 

Scale 6.336.000.
VANHISE.) THE CORDILLERAS. 327

beds was not determined. In places they constitute about a thousand 

feet of the altitude of the walls. These beds are traversed by dikes of 

granite, and beds of granite are found which are believed to be intrusive, hence of igneous origin. In some places the evidence is complete. 

An extensive period of erosion separates these schists and granite from 

the overlying Silurian and Devonian rocks.

In the Grand canyon are the records of an extensive period of deposition in the schists, followed by plication, erosion, fissuring and eruption. Again we have an invasion of the sea, which remains until 

10,000 feet of shales, sandstones and limestones are deposited; and 

this is followed by a dry-land period, marked in some places by at least 

10,000 feet of erosion and accompanied by plication, Assuring and 

eruption.

PowELL,69 in 1875, farther describes the Grand canyon group. TJnconforinably below the Carboniferous of the Kaibab plateau is a middle 

series of slates, sandstones and limestones 500 feet thick, so inclined that 

the total thickness of its beds is 10,000 feet. Below these are unconformably a thousand feet of crystalline schists with dikes of greenstone 

and beds of granite. This lower series is composed chiefly of metamorphosed sandstones and shales, which have been folded so many 

times, squeezed and heated, that their original structure as sandstones 

and shales is greatly obscured or entirely destroyed, so that they are 

metaniorphic crystalline schists. After these beds were deposited, 

folded and deeply eroded they were fractured, and through the fissures came floods of molten granite, which now stands in dikes or lies 

in beds, and the metamorphosed sandstones and shales, with the beds 

of granite, present evidence of erosion subsequent to the periods just 

mentioned, yet antedating the deposition of the nonconformable sandstones. Here, then, we have evidences of another and more ancient 

period of erosion or dry land. Three times has this great region been 

left high and dry by the ever-shifting sea; three times have the rocks 

been fractured and faulted; three times have floods of lava been poured 

up through the crevices, and three times have the clouds gathered over 

the rocks and carved out valleys with their storms. The first time was 

after the deposition of the schists; the second was after the deposition 

of the red sandstones; the third time is the present time.

GILBERT,36 in 1875, describes the axis of the Black and Colorado 

mountains in northwestern Arizona as consisting of granitoid rocks 

and highly crystalline schists. In Bowlder canyon of this range upon 

a nucleus of syenite are plicated crystalline schists. In Virgin canyon 

the nucleus is gneissic, with a general anticlinal structure. In Black 

canyon the nucleus is a homogeneous rock resembling pegmatite, but 

is probably metaniorphic.

In the Grand canyon of the Colorado theTonto sandstone rests directly 

on plicated and eroded schists and associated granites, and demonstrates 

them to be pre-Silurian. Following down the river the same relation is
328 PRE-CAMBEIAN ROCKS OF NORTH AMERICA. [BULL. 86.

seen in the Virgin range, and in the next ridge to the west, through which 

the river has cut Bowlder canyon, are gneisses so similar to those of the 

Virgin range that they may safely be classed with them. In Music mountain, in the Black hills near Prescott, and on Canyon creek, or, more generally, all along the southwestern border of the Plateau region in Arizona, 

the Archean schists and granites are seen beneath nonconforming members of the fossiliferous rocks, usually the Tonto sandstone. To the 

south and west of this line stretches a great ocean of inetamorphic ridges 

in which no one has found fossils. Whether a portion of the rocks are 

altered Paleozoic or whether the Paleozoic has been completely removed in the progress of erosion, or whether the Archean rocks have 

been covered by no later ocean sediments has not been decided. The 

purity and great thickness of the Carboniferous limestones up to the 

very margin of the region would appear to negative the idea of a permanent continent froni Archean time, if, indeed, it is not negatived by the 

survival of acute mountain ridges.

GILBERT, in 1875, describes the range region of western New 

Mexico and eastern Arizona. Northwest of the Burro mountains for 

50 miles are islands of Archean and Paleozoic rocks. The most conspicuous of the former is a deep-red granite. In the Santa Bita mountains the axial rocks are Archean schists. On the eastern border of 

the Plateau region is a chain of ranges which coalesces with the Eocky 

mountains of Colorado and consists mainly of Archean and Carboniferous rocks. The whole front of the Sandia mountains except the crest 

is Archean. The ZuSi range of the Plateau region has a crystalline 

nucleus which Howell suspects to be due to the inetainorphism of 

lower Paleozoic strata, as they are conformable with unaltered upper 

Paleozoic beds. The specimens show a gradation from compact sandstones to gneissic quartzite and quartzose granite. Between the 

Archean and the Silurian there is, first, a wide unconformity, demonstrating the tilting and erosion of the Archean beds anterior to the 

deposition of the Silurian; and, second, there is always at the contact 

a contrast of conditions as regards metamorphism, the Silurian rocks 

being usually merely indurated and the Archean invariably highly 

nietamorphic. The two characters of the break serve to show that it 

represents a vast chasm of time, a chasm the duration of which may 

have been greater than that of the ages which have since elapsed. A 

third character of the break, one that is supported by less evidence 

but is negatived by none, is that the lowest of the superposed rocks 

are conglomerates and coarse sandstones. The conclusion to be drawn 

from the coarse, fragmental nature of the lower deposits is that the 

water which spread them was an encroaching ocean, rising to possess 

laud that had long been dry. The recognized interpretation of a widespread sandstone is continental submergence, or, what is the same 

thing, an advancing coast line.

MARVINE,37 in 1875? states that granite is found below the Tonto
VAN HIM.] THE COEDILLERAS. 329

sandstone at the mouth of Grand canyon, at Music mountain, and in 

the canyon of New river. At Truxton and on the road to the southwestward granite occurs in the hills, often lava-capped; is found at Cross 

mountain, near fort Bock; at Aztec pass; at Juniper mountains; between Prescott and Agua Fria valley, and in the Black hills. In the 

Juniper mountains there are also found highly metarnorphic rocks, as 

schists, slates, etc., often covering considerable areas and with which 

many of the silver and gold bearing lodes of the country are associated. 

At camp Yerde on the river Yerde sedimentary rocks rest upon syenites. TheTonto sandstone rests upon the granite in the Sierra Ancha, 

in the San Oarlos valley, and in the Apache mountains. The main 

mass of the Final mountains is granite, but upon their northeast flanks 

is a long area of highly metamorphic rocks, consisting mostly of crystalline schists, micaceous, chloritic and talcose, their erosion forming 

an intricate maze of small valleys, separated by sharp ridges, which 

present a strong contrast with the more massive features of the mountains. The granites and schists of Final mountains extend along Final 

creek to camp Final.

FowELL,29 in 1876, further describes as unconformably below the 

Tonto sandstone the Grand canyon sandstones, shales and limestones, 

10,000 feet in thickness; and below this the Grand canyon schists, of undetermined thickness, composed of hornblendic and micaceous schists 

and slates, associated with beds and dikes of granite. The Grand 

canyon group rests unconformably upon the crystalline schists. The 

evidence of this is complete, for the lower sandstones and conglomerates first filled the valleys and then buried the hills of schistic rocks, 

and these conglomerates at the base of the group are composed of 

materials derived from the metamorphic hills about; and hence metainorphisin was antecedent to the deposition of the conglomerates. The 

plane of demarkation separating this group from the Tonto group is 

very great. At least 10,000 feet of beds were flexed and eroded in such 

a manner as to leave but fragments in the synclinals. Then followed 

a period of erosion, during which beds of extravasated material were 

poured over the fragments, and these igneous beds also were eroded 

into valleys prior to the deposition of the Tonto group. Fossils have 

beeb. found at the base of the Grand canyon series, but they are not 

well preserved and little can be made of them. Still, on geological 

evidence, these beds are considered Silurian.

WALCOTT,71 in 1883, describes below the Tonto a great series of 

uuconformable sediments which are divided into two groups, the Chuar 

and Grand canyon, between which there is an unconformity by erosion. 

The lower or Grand canyon group is made up of an immense mass of 

sandstones and interbedded greenstones, and the Chuar group is a 

series of sandy and clay shales. The Archean at the base of the Grand 

canyon group consists of thin-bedded quartzites broken by intrusive 

veins of a flesh-colored granite, the layers of quartzite standing nearly
330 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL.86.

vertical. The Grand canyon and Chuar groups unconformably deposited over the underlying Archean are referred to the Lower Cambrian 

and placed as the stratigraphical equivalent of the Keweenawau group 

of lake Superior. In the Grand canyon series are found a few obscure 

fossils. The Chuar and Grand canyon series are both wholly unmetamorphosed and but slightly disturbed.

WALCOTT,33 in 1886, states that the Tonto sandstone of the Grand 

canyon district is Upper Cambrian or Potsdam. Then below a great 

unconformity occurs by the erosion of an entire cross section of 13,000 

feet of strata of the Chuar and Grand canyon series; below the unconformable series rest unconformably on underlying highly inclined 

strata, which where the section terminates belong to a system of strata 

between the Grand canyon series and the Archean. On account of 

this great unconformity below the Tonto it is thought better to classify 

all the pre-Tonto strata as pre-Cambrian, the middle and lower Cambrian times being in the Grand canyon district a period of erosion. The 

Chuar formation or upper 6,000 feet of limestones and argillaceous 

shales lithologically resemble the Trenton limestone and Utica shales 

of the New York section. There is no evidence of the great age of 

these strata in their physical aspect. The lower 6,000 feet of Grand 

canyon formation are sandstones with interbedded lava flows toward 

the upper portions. ' Eipple marks and mud cracks a,bouud in many of 

the layers, but not a trace of a fossil was seen. Midway in the lower 

portion of the overlying Chuar strata the presence of a fauna is shown 

by a minute Discinoid or Patelloid shell, a small Lingula-like shell, a 

species of Hyolithes, and a fragment of what appears to have been the 

pleural lobe of the segment of a trilobite belonging to a genus allied to 

the genera Olenellus, Olenoides, or Paradoxides. There is also an obscure Stromatopora-like form that may or may not be organic. The 

fauna as given above is very unsatisfactory, but it shows the presence 

of a fauna that is Cambrian in character, as far as we know, although 

it may be a trace of a fauna preceding that of the Lower Cambrian of 

the Atlantic border; and as the stratigraphic evidence favors this view 

it is thought that it cannot be. considered of Cambrian age.

WALCOTT,35 in 1889, refers the section laid bare in the Grand canyon 

of the Colorado*to the Keweenaw group. This section presents o^ of 

the best opportunities known to the author for the discovery of a preOlenellus fauna.

WALCOTT,72 in 1890, gives the Algonkian section of the Grand canyon as follows: Chuar (shales and limestones), 5,120 feet; Grand canyon (sandstones with lava flows in upper part), 6,830 feetj Vishnu 

(bedded quartzites and schists), 1,000-f feet.

SUMMARY OF RESULTS.

It is evident from the literature that in western New Mexico and in 

the major part of Arizona is a fundamental, thoroughly crystalline
VAKHISE.] THE CORDILLERAS. 331

complex, consisting of most intricately mingled and folded granites, 

gneisses, micaceous and hornblendic schists, etc., precisely as in the 

previous sections concerned with the Rocky mountain system. This 

complex occurs at many points, constitutes the axes of many ranges, 

and its structure is of so intricate a character that no attempt has been 

made to estimate its thickness or to work out its structure, although in 

general the laminated rocks have been referred to as metamorphic. 

The granite in this complex plays the same part with reference to the 

crystalline schists as in the other areas referred to. Besides this ancient granite, which existed before the next newer series of rocks was 

formed, there is apparently in certain areas granites of later age, and ' 

these are more plentiful as the western part of Arizona is reached.

In eastern New Mexico and western Arizona, so far as the descriptions guide us, there is no certainty that any clastic -rocks exist older 

than the fossiliferous series. In the central part of Arizona, however, 

in the Colorado canyon district, is the most complete section of rocks 

older than the Cambrian and newer than the fundamental complex in 

any known part of the world, with the exception of the lake Superior 

region.

The Tonto sandstone of the Grand canyon region, called by Powell 

and Gilbert Silurian in accordance with the nomenclature of the time, 

by present classification is to be placed as Upper Cambrian. The great 

unconformity which separates this sandstone from the earlier series 

makes it very probable thatthe latter are pre-Cambrian. These inferior 

series in descending order are the Chuar, Grand canyon, Yishnu series 

(together the equivalents of PowelFs Grand canyon group), and the 

basal complex. The upper series consists of shales and limestones. 

Below this, with an erosion interval, is the second, consisting of sandstones, with interbedded and cutting basic eruptives. Inferior to this 

series, and separated by a great unconformity, is a set of thinly bedded 

and nearly vertical quartzites of undetermined thickness, broken by 

intrusive masses of granite. These three are clearly clastic series. The 

basal complex as described by Powell and Gilbert consists of thoroughly crystalline hornblendic and micaceous schists, gneisses, and 

granites, like the fundamental complex of the remainder of New Mexico 

and Arizona. Between this basal complex and the Yishnu series, as 

shown by Powell, is a vast unconformity. We have then in this region 

passing from the base upward, a fundamental complex; great unconformity; quartzite series of unknown thickness (Vishnu); great unconformity; Grand canyon series; minor unconformity; Chuar series; great 

unconformity; Cambrian.

The fundamental complex of Arizona has all the characteristics of 

the fiindamental complex of lake Superior. The next overlying series 

is a quartzitic one, and quartzite is one of the most abundant and characteristic formations of the Upper Huronian of the Northwest. The 

next great succession is the Grand canyon and Chuar series, which in
332 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [OTLL.M.

their unmetamorphosed condition, and in the character of the sediments are almost identical with the great thickness of sediments of the 

Keweenawan,. Also the eruptives, which are interbedded with the Grand 

canyon series and cut it, are practically identical with the basic eruptives 

of the Keweenawan. These interbedded and cutting greenstones 

are characteristic of the lower, but are not found in the higher series, 

a still further analogy with the Keweenawan, for the lower Keweena>wan contains eruptives and the upper Keweenawan is wholly detrital. 

The Grand canyon succession is then remarkably like that in the lake 

Superior region, and the respective series are lithologically alike.

It is exceedingly unsafe to correlate a single series with another series in a different geological basin upon lithological grounds; but when 

two great series of rocks are found, each of which has respectively similar 

lithological characteristics in two regions, and they are both separated 

by a physical break, and both sets of series are in exactly similar positions with reference to the overlying Cambrian and to the basement 

complex, the likeness suggests that they stand respectively as the time 

equivalents of each other. Between the two regions is the difference 

that in the Grand canyon area, a possible equivalent of the Lower Huronian of the lake Superior is not known. The correlation suggested 

can be considered no more than a conjecture since the parallelism in 

the two regions may be no more than a remarkable coincidence. It is 

remarked by Walcott that in the pre-Tonto series are a few obscure 

fossils, and that this locality is perhaps one of the best in the world in 

which to search for a pre-Cambrian fauna. Since in the lake Superior 

region the beginning of a pre-Oambrian fauna is also known, it may 

not be too much to hope that within a few years we shall have the 

assistance of fauna of sufficient fullness in these distant regions upon 

which the correlation above suggested may be tested.

SECTION VIII. CALIFORNIA, WASHINGTON AND BRITISH COLUMBIA.

LITERATURE OF CALIFORNIA, WITH ADJACENT PARTS OF NEVADA AND ARIZONA.

DANA,73 in 1849, describes various crystalline rocks in the TJrnpqua 

and Shasty ranges. These include granite, syenite, porphyry, talcose 

rocks, serpentine. The hornblendic and talcose rocks are rarely schistose. Associated with the former rocks are conglomerates and sandstones.

TYSON,74 in 1850, describes sections in the Sierra Nevada and the 

Coast range. The rocks are, first, metamorphic, consisting of those of 

sedimentary origin, such as slate, but subsequently altered by the 

effects of heat, and second, of hypogene rocks, which include granite, 

trap rocks, and others. At the summit of the Sierra, granite is 

the prevailing rock, and upon its flanks slates. The cleavage of 

the slates have a uniform course, about north of west. These lines of 

cleavage are usually taken for those of stratification, but it is fre-
VAN RISE.] THE CORDILLERAS. 333

quently difficult to determine the stratification even where extensive 

excavations have been made. However nrach the slates have been 

disturbed during their period of upheaval, they assume the slaty 

structure in continuous or parallel lines extending over considerable 

distances in the present instance for more than 70 miles the inclination being nearly vertical.

BLAKE,81 in 1856, states that the contorted gneisses of the Aquarius 

mountains are metamorphic. In the Aztec mountains the horizontal 

Carboniferous strata show that it was an ancient granitic uplift. The 

specimens of granite are of a red or rose color, few or none being white 

or light gray, in this respect contrasting strongly with the collection 

made from the Sierra Nevada and the Bernardino Sierra, as well as 

from those of the Great basin and along the Mojave river. The metamorphic rocks are in all probability not older than the Silurian or Carboniferous. This is certainly the case in the Aquarius mountains. In 

the rapid reconnaissance of these disturbed and metamorphic rocks it 

was not possible to bestow the attention upon them which their obscured condition demands, and it is therefore not possible to assign a 

dividing line between the truly erupted granitic rocks and those which 

simulate them but in reality are of sedimentary origin.

DEWBERRY,75 in 1856, states that in the coast mountains are found 

occasional protrusions of granite and serpentine. The great mass of 

the Sierra Nevada is composed of plutonic or volcanic rock, granite, 

gneiss, mica-schists and porphyries, traps, trachyte, etc., with auriferous talcose slates and veins of quartz. The western slope of the Cascade mountains in one place where crossed is composed of trappeau 

and metamorphic rocks.

ANTiSELL,76 in 1856, states that in the Coast range the igneous rocks 

that form the axis are of two kinds, granitic and trachytic. While altogether distinct in their extreme types, when they approach each other 

in position and age they merge these separate differences. The granites of the Sierra Nevada are anterior to the Eocene and posterior to 

the later Paleozoic. All of the observed sedimentary rocks were postCretaceous. Granitic and primary metamorphic rocks are mentioned 

as occurring at several places in the Coast range, and in the Cordilleras in many localities. At one locality hornblende-gneiss is found.

BLAKE,77 in 1857, states that granite is found at points along the 

coast from Monterey to near the Golden Gate. At the Tejon, in the 

Sierra Nevada, the rocks now generally classed as metamorphic, such 

as gneiss, mica-schists, hornblende-slate and chlorite-slate, are predominant. While these rocks are probably a metamorphosed sediment, the linear arrangement of the minerals is not regarded as satisfactory evidence of it. This structure also appears when the rocks 

are so far fused as to obliterate the original planes of stratification, and therefore the words strata or stratification in relation to 

these rocks are avoided, but to designate the lines or layers of minerals
334 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

are used planes of structure or lamination. At one section was found 

granite, upon both sides of which is white limestone; next to the latter, 

on one side is quartz rock, which is followed by chlorite-slates. If the 

structural relations were regarded as conclusive evidence, the whole 

series would necessarily be considered metamorphic; but there is little 

reason to doubt that the granite is eruptive. The metamorphism in 

the limestone is complete and resembles the coarsely crystalline white 

limestones of Sussex county, New Jersey. There is no indication as 

to the age of the limestone or quartz rock, but there is some reason to 

regard them as Carboniferous, for these are the nearest known formations of limestone which are recognizable by fossils. On the section 

of the CaSada de las TJvas the rocks are similar to those of the western 

slopes of the Tejon. Along the Mojave river the rocks consist of metamorphic slates, very compact and so much changed as to resemble 

granite. In the Colorado desert the most of the metamorphic rocks 

are highly laminated and contain lenticular beds of limestone. In the 

gold region talcose and clay-slates are the prevailing rocks, and in general present a low degree of metamorphism. Next to the slate in 

importance is white crystalline limestone.

EMORY,78 in 1857, states that in southern California there is a great 

preponderance of crystalline metamorphic granite pertaining to the 

older Paleozoic series of rocks and an entire absence of any member 

of the lower Paleozoic or secondary rocks in their regular stratified 

character. The central axes are represented by somewhat variable 

granite, assuming in some places a close syenitic texture and at other 

times there is a preponderance of mica. Belonging with the granitic 

series, particularly on the eastern side of the range, are mica and talcose slates.

NEWBERRY,79 in 1861, describes the great mass of the Peninsular 

mountains east of San Diego as composed of granitic and gneissoid 

rockSj which are similar to most of the granites of the other systems 

of the Colorado j that is, a predominance of the feldspathic over the 

hornblendic ingredients. Where the Colorado cuts through the Chocolate mountains they are composed of gneisses traversed by veins of granite and quartz. The gneissoid rocks are frequently foliated and much 

convoluted. Their aspect is such as to lead an observer more readily to 

refer them to a metamorphic origin than any other rocks seen on the 

route. The great- mass of Monument mountains is a coarse, massive 

feldspathic granite. On both sides of the granitic axis are highly metamorphosed conglomerate and sandstone. The principal mass of the 

Mojave mountains is composed of white granite, traversed by numerous 

veins of quartz. The Black mountains as a whole are characterized by 

the prominence of eruptive rocks, such as massive granite, trap, porphyry and trachyte, and the rarity of gneiss, mica slate, clay-slate, 

etc., which are probably metamorphic. In the lower Colorado canyon, 

unconformably below the Potsdam sandstone, is granite, which is cut
VANHISE.] THE CORDILLERAS. 335

by veins of quartz and red syenite. This sandstone is somewhat metamorphosed, but its consolidation is not due to volcanic heat, but rather 

to molecular changes induced by long-continued pressure of the immense mass of superincumbent rocks. The Cerbat mountains have a 

core of granite.

WniTNEY,80 in 1865, describes the Coast range, the region between 

the Canada de las Uvas and Soledad pass, and the Sierra Nevada, in 

all of which regions are found granitic and metamorphic rocks.

Granite occurs at many points in the Coast range and is described 

and figured as breaking through the Cretaceous and Tertiary strata 

and metamorphosing them.

In the Canada de las Uvas region, at San Emidio canyon, occur gran- 

'ite, mica-slate, syenite, hornblende-slate and limestone, turned on end 

and unconformably overlain by unaltered Cretaceous and Tertiary 

strata. In the Tejoii pass are found mica-slate, granite, gneiss, and 

syenite. Near the fort occurs crystalline limestone associated with 

mica-slate and gneiss, together with magnetic iron ore.

At many localities in the Sierra Nevada are described areas of granite, many of them of great magnitude. With them are associated metamorphic slates, a portion of these being mica-slates. In places granite 

dikes and veins are seen to intrude the slates. At Dome mountains, 

near the head of Kern and Kings rivers, a granite has a peculiar concentric dome structure which is not regarded as due to sedimentation, 

but results from the cooling of igneous material. The few fossils described in the slates of the Sierra are such as to cause them to be 

referred to the Jurassic.

GILBERT,36 in 1875, states that in the Inyo range are found syenite, 

granite and gneissoid rocks. On its east face quartzites, siliceous 

schists, green schists and limestones make the section over 1,100 feet 

thick. In the Amargosa range the Whites peak series is 11,500 feet 

thick, and is composed of quartzites, green garnetiferous schists and 

siliceous and argillaceous schists. Atthebase of the section in the Amargosa range is 900 feet of quartzite resting conformably upon 600 feet 

of mica-schist and chlorite-schist. A section at Boundary canyon 

2,500 feet thick is made up of limestones, micaceous and other schists 

and quartzites. None of these rocks are regarded as pre-Silurian. 

Although no fossils are found, the Whites peak section is presumptively Silurian.

MARCOU,81 in 1876, states that granitic rocks occur in the Sierra 

Madre in southern California at a number of points. This mountain 

chain is described as the most ancient of the modern chains of southern 

California; that is to say the granite, pegmatite, gneiss and metamorphic rocks which form its principal mass date from times anterior to 

the Paleozoic.

LOEW,82 in 1876, states that nearly all the mountain ranges of southern California belong to the Primitive formation. In the San Bernar-
336 PRE-CAMBRIAN BOCKS OF NORTH AMERICA. [BULL. 86.

dino mountains the main mass is granite, accompanying gneiss, micaschist, talcose schist and primitive clay-slate. The River-Side and 

Half-Way mountains consist of granite and gneiss. At the Mojave 

range is a series of Azoic rocks consisting of fine grained granite, 

syenite, hornblende-schist and quartzite. At the Panamint range are 

primitive limestone and clay-slate as accompaniments of the granite. 

Eruptive gneiss is found in the Coahuila valley which has metamorphosjed the limestone on either side. The gneiss shows by the position 

of its mica plates a stratification parallel to the limestone layers, indicating the effect of pressure during the consolidation of the injected 

rock mass. Eruptive syenite occurs in the Buena Yista and Inyo ranges 

and eruptive granite at Dead mountains and in the Opal ranges. Occasionally in th£ San Bernardino mountains the granite gives rise to the 

formation of* beds of arkose, a rock in which granitic d6bris has been 

recemented, forming a sort of granitic sandstone resembling to some 

extent granite, but the uniform grain, friability, and rusty surface of 

the fragments elucidate its true nature.

NEWBERRY,54 in 1876, states that in the Aquarius range the Carboniferous strata rest directly upon the granite. In the Cerbat mountains 

gray granitic rocks are found upon which rest unchanged Carboniferous 

strata. In the mountains of the lower Colorado metamorphic rocks are 

abundant, consisting of gneiss, mica-slate and clay-slate, talcose slate 

and limestone, the latter highly metamorphosed and crystalline, forming marble, so far as observed, wholly destitute of fossils. This metamorphic limestone of the Sierra is suspected to be Carboniferous.

CoNKLiNG,83 in 1877, states that the ridge-like line of the eastern 

summit of the Sierra consists entirely of granite, flanked in several 

places by igneous rocks. In the Western Summit range are also found 

granitic rocks.

CoNKLiNG-,84 in 1878, describes portions of western Nevada and eastern California, including a part of the Sierra range, and finds little 

aside from metamorphic and igneous rocks. Granite is found at many 

localities.

BEOKER,85 in 1888, states that granite underlies the Coast ranges and 

the Sierra Nevada. The evidence in California is in favor of the hypothesis that the main mass of the underlying granite is primeval. 

While it is not absolutely certain that Archean rocks occur in California, the unquestionable occurrence of the Archean in Arizona, together 

with the similarity of the rocks of southeastern California to those of 

the adjacent territory, make it probable that San Bernardino county is 

largely Archean. In the Gavilan range the lowest sedimentary formation is a crystalline limestone, associated with which are rocks of the 

Archean gneiss type. It is possible that it is a member of the Knoxville series more metamorphosed than usual, but it appears more probable that it is a remnant of some older formation which has perhaps
VANHISE.] THE CORDILLERAS. 337

undergone repeated metamorphism. Aside from these the earliest 

metamorphic rocks of the coast are probably Cretaceous.

BECKER,80 in 1891, describes the sierra between the Stanislaus and 

Truckee rivers as being chiefly granite and diorite overlain in part by 

andesite and basalt. The granite and other granular rocks are intersected by fissures at short intervals which are believed to be early Cretaceous.

LITERATURE OF WASHINGTON.

GrBBS,87 in 1855, states that in central Washington, in the valley of 

the Methow, is found granite, syenite and gneiss, well characterized 

and blended with each other. The syenite is often divided by joints so 

as almost to appear stratified and to give its perpendicular walls the 

semblance of artificial construction. The gneiss is found both horizontal and displaced by the intrusion of trap. Along the.Columbia 

river was found syenite, granite, gneiss, quartzose rocks, talcose slate 

and greenstone.

LITERATURE OF BRITISH COLUMBIA.

RICHARDSON,88 in 1872, mentions crystalline rocks on the east coast 

of Vancouver which are pre-Carboniferous and may be of Laurentiau 

age.

RICHARDSON,89 in 1873, finds below the coal-bearing series of Vancouver and Queen Charlotte islands crystalline limestones, diorites, red 

and green slates, the age of which is uncertain, but are probably Silurian or later.

RICHARDSON,90 in 1876, finds crystalline rocks throughout a widespread area in British Columbia, extending through 7 degrees of latitude, from New Westminster on the Fraser river to Wrangel on the 

Stickeen river, and through 6 degrees of longitude, from .Vancouver to 

Cariboo and Tete Jaune cache. While not able to speak authoritatively on the age of this great series of crystalline rocks or to say 

whether different portions of them will be proved to belong to distinct 

epochs, they present such a wonderful uniformity in character as to 

favor the idea that they constitute one great and widespread series. 

They are doubtless the gold-bearing rocks of British Columbia.

SELWYN,91 in 1877, in a report on exploration in British Columbia, 

divides the rocks into five divisions from above downward. Division 

four consists of semicrystalline rocks, among which are limestones, 

shales, mica-schists and quartziibes, which appear to have obscure fossils. The age of these rocks is not clearly determined. Division five 

consists of granitic rocks.

MACOUN,92 in 1877, finds granite-gneiss and gneiss a few miles up the 

Quatre Fourches river, which are referred to the Laurentian.

DAWSON, (Gr. M.)93 in 1877, states that a crystalline series occurs in 

the Cascade mountains about Eagle and Tatla lakes. These are chiefly 

highly crystalline gneisses, granites and diorites. 

Bull. 86 22
338 PRE-CAMBKIAN ROCKS OF NORTH AMERICA. [BULL.86.

DAWSON (G. M.),94 in 1878, states that the crystalline series of Vancouver, described by Bichardson in 1872, are found to contain fossils. 

They have, however, become metamorphosed, and in lithological character resemble the Huronian and altered' Quebec groups of eastern 

Canada.

DAWSON (G. M.),95 in 1879, describes in some detail the Cascade 

crystalline series, which are referred to the Carboniferous period. The 

only rocks tentatively referred to the Laurentian are crystalline rocks 

of Shnswap lake and the gold range, which comprises gneisses, greenstones, schists, limestones and granites.

BAUERMAN,96 in 1885, describes, near the forty-ninth parallel, west of 

the Eocky mountains, large areas of crystalline rocks, among which 

are granites; gneisses, basalt, etc. The gneiss of Spokane resembles 

the typical Laurentian gneiss of Canada. The metamorphic slates and 

greenstones perhaps belong to the Huronian.

DAWSON (G. M.),97 in 1886, in that portion of the Eocky mountains 

between latitudes 49° and 50° 30', places the lowest rocks found in the 

Cambrian. These comprise quartzite, quartzitic shales, argillites, 

limestones, and conglomerates. One section, between South Kootanie 

pass and Flathead river, has a maximum thickness or more than 11,000 

feet. These rocks are apparently destitute of fossils and are compared 

in their lithological character with the Cambrian of the Wasatch, but 

they have a still closer resemblance to the Chuar and Grand canyon 

groups of the Colorado river.

DAWSON (Gr. M.),98 in 1887, describes Vancouver island and the adjacent coasts. All the stratified rocks are Cretaceous or Triassic, 

although they are often metamorphic and crystalline. To all the volcanic material underlying the Cretaceous, including the limestones, 

argillites and qnartzites, the term Vancouver series is applied. These 

rocks, the oldest in the district, were not deposited upon a granitic 

floor, as the granites are evidently later in date, and nothing is known 

of the character of the surface upon which the Vancouver beds were 

deposited. Granitic rocks are very widespread. The granites near 

the line of junction with the Vancouver series are charged with innumerable darker fragments from that series. In the immediate vicinity of the parent rock they are angular and clearly marked, but at a 

greater distance are rounded and blurred in outline. The width of the 

belt in which these fragments occur may exceed half a mile; in other 

cases it is only a few hundred feet. It was in several instances found 

impossible to draw a distinct line between the granites and the Vancouver rocks. The Vancouver series for some distance from the contact 

is very generally shattered and penetrated by granitic spurs or by felsite dikes. If the granite were in limited intrusive masses these would 

be regarded as ordinary intrusive rocks, but it appears everywhere to 

be the material upon which the Vancouver series rests, and is nevertheless evidently of later date than these rocks. The only explana
VANHISE.) THE COEDILLERAS. 339

tion which appears satisfactorily to account for the appearances met 

with is that in consequence of upheaval and denudation we now 

have at the surface a plane which was at one time so deeply buried 

in the earth's crust that the rocks beneath it had become subject to 

granitic fusion. It is clear that the granitic rocks beneath were 

in a plastic condition, not alone from the fact that they are found to 

penetrate the older series, but also from the evidence everywhere met 

with of the .scattering out of fragments of the stratified rocks into the 

granites. Both the granites and the rocks of the Vancouver series have 

been subjected to great pressure in a horizontal direction, causing the 

fragments in the agglomerates to assume lenticular forms and impressing a more or less distinctly schistose character upon them, while the 

dark included fragments in the granites have been squeezed out into 

sheets, giving the portions of these rocks which are characterized by 

an abundance of such ^fragments an almost gneissic lamination. At 

the time at which this effect was produced the granites must still have 

been in a plastic state. On the inner side of Vancouver island it may 

further be remarked that for a long stretch the flaggy argillites and 

quartzites are frequently directly in contact with the granitic rocks, 

rendering it probable that the refractory character of their materials 

has proved a sufficient barrier to the progress of the granitic change, 

which may, locally, have nearly reached its possible limit. Particular 

occurrences of granite at many localities are described in detail.

McCONNELL," in 1887, describes the Bow river series in the eastern 

part of the Eocky mountains. It consists of dark-colored argillites, 

associated with sandstones, quartzites and conglomerates. The base 

is not seen, but the part exposed has an estimated thickness of 11,000 

feet. The argillites are occasionally cleaved and have scales of mica 

often developed along the divisional planes. The only fossils obtained 

from this formation are u couple of trilobitic impressions, one of which 

was identified by Walcott as Olenellus gilberti.

Bo WHAN,100 in 1889, states that certain schists are found in the Cariboo gold belt of British Columbia, which are referred to the lower 

Paleozoic. These consist in the main of slates and sandstones, the 

total thickness being placed in the neighborhood of from 5,000 to 8,000 

feet. No fossils are found, and their position as lower Paleozoic is 

tentative. In the Alpine region of Cariboo are found gneisses, granites and quartzites, which resemble the characteristic rocks of the 

Archean. Associated with these are lower granitic rocks. The entire 

crystalline series of the gold region of Cariboo is lithologically identical, as near as can be described in general terms, with the rocks of the 

l^re-Cambrian. and Cambrian gold regions of eastern Canada. The 

gneissic and schistose type of rocks of the mount Stevenson group 

especially (supposed to represent the lowest horizon, on account of their 

association with granite in a central and massive mountain group)
340 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

finds lithological representatives in the pre-Cambrian rocks of the eastern provinces of the Dominion and in the Appalachian axis.

DAWSON, (G-. M.) 101 , in!891, describes a section in the Selkirk range 

and compares it with a section of the interior plateau region at Kootanie 

and Adams lakes and on the west side of the Bocky mountains. The 

sections are given and correlated as follows:

Provisional comparative table of formations met with (1) in the eastern border of the interior plateau of British Columbia, (#) in the Selkirk range, and (3) on the western side 

of the adjacent portion of the Eocky mountain ranges.

1. Section on Kootanie and 

Adams lakes.

Feet. 

6. Greenish and 

gray schists, 

with lime5. Limestone o r 

marble with

argillites and 

8 o in e gray

g 4. Chiefly green- 

*B ish, with some

<o 3. Chiefly gray, 

 g with some 

 ~J greenish 

g schists ...... 8,550

3*H

o5 2. Black, shaly or 

.2 schistose arS gillite, with 

m some linie3 or more.

0

fc

i* 1. M i c a -schists, 

£ o gneisses, and 

g'g marbles ..... 5,000 

lg a or more.

2. Section in the Selkirk range 

on line of Canadian Pacific 

Bail way.

, Feet. 

Quartzites, with gray 

schists and some 

limestone.

limestone, and gray 

schists.

Gray schists and 

£ Sra7 quartettes,

<g ose conglomerate 

w and interbedded 

3 blackish argil- 

^ lites, the last 

,® chiefly to ward the 

m base............. 25,000

a! Blackish argillite- 

 2 schists and pliylo lites, generally 

£ calcareous, with

^ stone and quartz- 

§ ite. .............. 15,000

.2

g

%j Gray gneissic 

^o rocks and coarse 

g'g mica-schists... 5,000 

A a or more. to

3. Section in the Eocky mountains (west side of range, 

McConneU).

Feet, 

Halysites beds, dolomites, and quartzites 1, 300 

or more.

shales. Black fissile 

argillites, with some

d Green ish and gray 

'§ calc-schists and

g ft reddish shales 

g § and slates, with 

<u Ijj some dolomitic 

^ limestone...... 10,000 

cs (probably).

m D a r k argillitea, 

.2 with some quarfa- 

® ites and conglom- 

" erates, the latter

£ toward the sum-

| seen ............. 10,000

pq or more.

d Silurian.

1 

§

ti 

3

ti

1 O

d

Cambria

Archean.

Associated with the Archean schists are certain granitoid rocks which 

may represent either portions of the schists in which the bedding has 

been obliterated or very ancient intrusives. Besides these there is at 

least one later series of intrusive granites which are probably later than 

most of the Paleozoic rocks. The Shuswap series of the Adams lake 

section appears to be traceable on their line of strike into diabases and 

diabase rocks, which are often agglomerates and pass into volcanic ash 

rocks. . In the Shuswap series of the Selkirk nearly half of the entire 

mass of the rocks exposed consist of intrusive or vein granite with 

pegmatitic tendencies. In the Msconlith series the lamination is often 

true bedding, but in some cases a slaty cleavage is developed. In the
VAN IIISB.] THE CORDILLERAS. 341

Castle mountain group and the upper 3,000 feet of the Bow river series 

of the Eocky mountain section the Olenellus fauna is found. Nowhere 

in any of the sections were unconformities seen. In sections 1 and 2 

no fossils have been discovered. The correlations are made upon relative positions and lithological grounds. Between the Shuswap and 

overlying series there is believed to be a great time break, for this 

lower series is of a markedly more crystalline character, and the numerous granite .veins which everywhere cut it at no point enter the overlying Cambrian strata. The rocks placed in the Cambrian are then 

40,000 feet thick. The use of the term Algonkian to designate the 

rocks conformably below the Olenellus fauna is objected to, it being 

more philosophical to include, for the present at least, the whole of this 

great conformable mass of rocks to its base under the name Cambrian.

SUMMARY OF RESULTS.

The literature of the vast region covered by the western coast ranges 

and British Columbia is too meager to make possible any systematic 

comparisons between the rocks of different districts. No attempt has 

been made accurately to map any considerable areas in the region. 

The crystalline series have been referred to the pre-Cambrian, Cambrian, Huronian, or Laurentian, as the particular author thought advisable.

In California, Whitney evidently regarded all of the granites and 

metamorphic rocks as of very late age, but Becker, on the contrary, 

regards the main mass of them as the equivalent of the most ancient 

complex of Arizona and other western Territories. The earlier observers, such as Antisell, speak of the granites and metamorphic rocks 

which'occur in the different ranges as Primary, but this reference was 

clearly made upon lithological grounds. While nothing definite can be 

said, the descriptions of some of the areas in southern and southeastern California and in the district along the Canada de las TJvas certainly suggest that in these districts are thoroughly crystalline complexes which are lithologically like the fundamental complex of the 

Eocky mountain region, but it can not be positively asserted that anywhere in this region, except in British Columbia, such an ancient rock 

system has been found. Here the recent work of Dawson has shown 

the existence of a fundain»ntal complex in all respects like that found 

in the Eocky mountains of the United States.

Nothing definite can be said as to the existence in California of preCambrian clastic series later than such a possible fundamental complex. It is not at all impossible that such great series of crystalline 

schists as that described by Gilbert at Whites peak, in the Amargosa 

range, is the equivalent of the elastics of the Grand canyon group. 

This series was by this author referred to the Silurian5 but the Grand 

canyon series at that time, when the lowest fossiliferous rocks were so 

called, was also called Silurian.
342 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BUM, 86.

Iii British Columbia the lower 7,000 feet of the Bow river series of rocks 

may be pre-Olenellus, and not improbably belong to the Algonkian under our usage of the term, although placed by Dawson under his usage 

as a part of the Cambrian. If a part of this Bow river series is Algonkian, it would carry with it also, in all probability, the Msconlith series, 

with possibly a portion of the Selkirk series, and doubtless also a portion at least of the section at Kootanie and Adams lakes; hence it is 

not improbable that in British Columbia is a great area in which Algonkian rocks occur.

NOTES.

1 Exploration and Survey of the Valley of the Great Salt Lake of Utah, including 

a Reconnaissance of a New Route through the Rocky Mountains, Capt. Howard Stansbury. Washington, 1853,495 pp., atlas of 2 maps. Abstract taken from edition of 

1855, published in Philadelphia.

2 On the Geology and Natural History of the Upper Missouri, F. V. Hayden. Trans. 

Am. Phil. Soc., vol. xn, new series, 1863, pp. 1-218, with a geological map.

3 Geological Report, F. V. Hayden. Third Annual Report of the U. S. Geological 

Survey of the Territories, embracing Colorado and New Mexico, pp. 109-199.

4 Report of F. V. Hayden. Preliminary Report of the U. S. Geological Survey of 

Wyoming and portions of contiguous territories (being Fourth Ann. Rept. of Prog.), 

pp. 1-188.

B Report on the Geology of the Country between Fort Leavenworth, Kansas, and 

the Sierra Nevada, near Carson Valley, Henry Engelmann. Report of Explorations 

across the Great Basin of the Territory of Utah for a direct Wagon Route from 

Camp Floyd to Genoa, in Carson Valley, in 1859, by Captain J. H. Simpson, pp. 

247-336.

6Descriptive Geology, Arnold Hague and S. F. Emmons. U. S. Geological Exploration of the Fortieth Parallel, Clarence King, Geologist in Charge, vol. n, 890 pp., 26 

plates. See also vol. i.

7 Systematic Geology, Clarence King. U. S. Geological Exploration of the Fortieth 

Parallel, vol. 1,803 pp., with an atlas.

8Report on the Geology of the Sweetwater District, F. M. Endlich. llth Ann. 

Rept. U. S. Geol. and Geog. Survey of the Territories, embracing Idaho and Wyoming, 

being a Report of Progress of the Exploration for the year 1877, pp. 1-158.

9Based on unpublished field-notes made by C. R. Van Hise, in the summer of 1889.

10 Sketch of the Geology of the Country about the Head Waters of the Missouri 

and Yellowstone rivers, Dr., F. V. Hayden. Am. Jour. Sci., 2d ser., vol. xxxi, 1861, 

pp. 229-245.

11 Second Annual Report of the U. S. Geological Survey of the Territories, embracing Wyoming, F. V. Hayden, pp. 65-102.

lz Report on the Geology and Natural History of the Big Horn Mountains, W. L. 

Carpenter. Reports of Inspection made in the summer of 187-7, by Genls. P. H. Sheridan and W. T. Sherman, of country north of the Union Pacific Railroad, pp. 11-19.

"Remarks upon the Geology and Physical Features of the Country West of the 

Rocky Mountains, with miscellaneous facts. John Ball, Am. Jour. Sci., 1st ser., vol. 

xxviii, pp. 1-16.

"Geological Report, Theodore B. Comstock. Report upon the reconnaissance of 

Northwestern Wyoming, including Yellowstone National Park, made in the summer 

of 1873 by William A. Jones, pp. 102-116, with a geological map of western Wyoming.

"Report on the .Geology of the Green River. District, A. C. Peale. llth Ann. Rept. 

U. S. Geol. and Geog. Survey of the Territories, pp. 509-646.

16Report on the Geology of the Wind River District, Orestes St. John. 12th Ann.
VANHISB.] THE CO.RDILLERAS. 343

Eept. U. S. Geol. and Geog. Survey of the Territories, F. V. Hayden, part 1, pp. 

173-269.

"Report of the Geological Field-work of the Teton Division, Orestes St. John, 

llth Ann. Kept. U. S. Geol. and Geog. Survey of the Territories, F. V. Hayden, pp. 

321-508.

18 Report of Frank H. Bradley, Geologist of the Snake River Division. 6th Ann. 

Rept. U. S. Geol. Survey of the Territories, F. V. Hayden, pp. 189-271.

19 Report of F. V. Hayden. Preliminary Report of the U. S. Geol. Survey of Montana and portions of adjacent Territories; being a 5th Ann. Rept. of Progress, pp. 

13-165, with maps.

20 Report on the Minerals, Rocks, and Thermal Springs .of the region traversed by 

Hayden, A. C. Peale. Ibid., pp. 165-204.

21 Report of F. V. Hayden. 6th Aun. Rept. U. S. Geol. Survey of the Territories, 

pp. 11-85.

22 Report of A. C. Peale. Ibid., pp. 97-187.

23 Notes Descriptive of some Geological Sections of the Country about the Head 

Waters of the Missouri and Yellowstone Rivers, F. V. Hayden. Bulletin of the U. S. 

Geol. and Geog. Survey of the Territories, vol. n, pp. 197-209.

24 Report on the Geology of the Yellowstone National Park, W. H. Holmes. 12th 

Ann. Rept. U. S. Geol. and Geog. Survey of the Territories, part 2, pp. 1-62.

28 Relation of the Coal of Montana to the Older Rocks, W. M. Davis. Tenth Census 

of the United States, vol. 15, pp. 697-712.

26From unpublished manuscript on The Paleozoic Section in the Vicinity of Three 

Forks, Montana, A. C. Peale.

27 On the Geology of the Eastern Uintah Mountains, 0. C. Marsh: Am. Jour. Sci., 

3d ser., vol. I, pp. 191-198.

28 Repprt of Explorations in 1873 of the Colorado of the West and its Tributaries, 

J.W.Powell,pp.36.

' " Report on the Geology of the Eastern Portion of the-Uiuta Mountains and a 

region of country adjacent thereto, J. W. Powell. U. S. Geol. and Geog. Survey of the 

Territories, 218 pp., with atlas.

30 Geological and Mineralogical Notes on some of the Mining Districts of Utah Territory, and especially those of the Wasatch and Oqnirrh Ranges of Mountains, B. 

Silliinan. Am. Jour. Sci., 3d ser., vol. in, pp. 195-201.

31 Report on the Geology of portions of Utah, Nevada, Arizona, and New Mexico, 

examined in the years 1872 and 1873, E.E. Howell. Report upon Geographical and 

Geological Explorations and Surveys west of the One Hundredth Meridian, vol. m, 

Geology, pp. 227-301, with atlas sheets.

3-2 On the Archean Rocks of the Wasatch Mountains, Archibald Geikie. Am. Jour. 

Sci., 3rd ser., vol. xix, pp. 363-367.

33 Second Contribution to the Studies on the Cambrian Faunas of North America, 

C. D. Walcott. Bull. U. S. Geol. Survey No. 30, 369 pp., 33 pis. See also The Cambrian 

system in the United States and Canada, C. D. Walcott. Bull. Phil. Soc. Washington, 

vol. VI, pp. 98-102.

34 Geology and Mining Industry of Leadville, Colorado, S. F. Emmons. Monograph 

12 U. S. Geol. Survey, xxix, 770 pp., 45 pis., and atlas of 35 sheets folio, pp. 308-311.

35 Stratigraphic Position of the Olenellus Fauna in North America and Europe, 

Charles D. Walcott. Am. Jour. Sci., 3rd ser., 1889, vol. xxxvn, pp. 374-392; vol. 

xxxviir, pp. 29-42.

36 Report on the Geology of portions of Nevada, Utah, California, and-Arizona, 

examined in the years 1871 and 1872, G. K. Gilbert. Report upon Geographical and 

Geological Explorations and Surveys west of the One-Hundredth Meridian, vol. m, 

Geology, pp. 16-187, with atlas.

37 Report on the Geology of Route from St. George, Utah, to Gila River, Arizona, A. 

R. Marviue. Ibid., pp. 189-225, with atlas sheets.
344 PRE-CAMBRIAN BOOKS OF NORTH AMERICA. [BULL. 80.

38 Geological Report of the Country Explored under the Twenty-eighth and Fortyfirst parallels of North Latitude, in 1853-'54, James Schiel. Reports of Explorations 

and Surveys fora railroad from the Mississippi River to the Pacific Ocean, in!853-?54, 

vol. n, pp. 96-107.

39 Abstract of Report on Geology of the Eureka District, Nevada, Arnold Hague. 

Third Ann. Rept. U. S. Geol. Survey, for l881-'82, pp. 237-290, 8 pi.

40 Account of an expedition from Pittsburg to the Rocky Mountains, performed in 

the years 1819 and 1820, by order of the Hon. J. C. Calhoun, Secretary of "War, Major 

Stephen H. Long. Philadelphia, 2 vols., with an atlas; pp. 503, 442, xcvm.

41 Report on the Geology of the region traversed by the Northern or Middle Park 

Division during the working season of 1873, Arch. R. Marvine. Seventh Ann. Rept. 

U. S. Geol. and Geog. Survey of the Territories, pp. 83-192, with atlas sheets.

42 Report on the South Park District during the season of 1873, A. C. Peale. Ibid., 

pp. 193-273. With atlas sheets.

43 Report of F. M. Endlich. Ibid., pp. 275-361. With atlas sheets.

44 Report on the Geology of a portion of Colorado examined in 1873, John J. Stevenson. Report upon Geog. and Geol. Explorations and Surveys west of the One 

Hundredth Meridian, vol. in, Geology, pp. 303-501. With atlas sheets.

4S Orographic Movements in the Rocky Mountains, S. F. Einmons. Bull. Geol. Soc. 

America, vol. I, pp. 245-286.

46 Based on unpublished field notes made by Prof. Arthur Lakes in the summer of 

1890.

4T Report on the geology of that part of northwestern New Mexico examined during the field season of 1874, E. D. Cope. Report of the Chief of Engineers for 1875, 

Appendix LL, Part 2, pp. 921-1108.

48 Geological Report on the Southeastern District, F. M. Endlich. 9th Ann. Rept. 

U. S. Geol. and Geog. Survey of the Territories, pp. 103-235. With atlas sheets.

49 Report on the Geology of the White River District, F. M. Endlich. 10th AnnRept. U. S. Geol. and Geog. Survey of the Territories, pp. 61-131.

60 Memoir of a Tour to Northern Mexico, connected with Col. Doniphan's Expedition in 1846 and 1847, A. Wislizenus. Senate Miscellaneous Docs., No. .26, 1st sess. 

30th Cong., 1848, 141 pp. With map.

61 General Report upon the Geological Collections, William P. Blake. Report of 

explorations and surveys to ascertain the most practicable and economical route 

for a railroad from the Mississippi River to the Pacific Ocean, in 1853-'54, vol. ill, pp. 

119. With a geological map.

62 Geological and Mineralogical Report on portions of Colorado and New Mexico, 

Dr. O. LOCAV. Report of the Chief of Engineers for 1875, Part n, Appendix LL, pp. 

1017-1036.

63 Notes on the Geology of Northeastern New Mexico, Orestes St. John. Bull. U. 

S. Geol. and Geog. Survey of the Territories, vol. n, pp. 279-308.

64 Geological Report, J. S. Newberry. Report of the Exploring Expedition frW 

Santa Fe, New Mexico, to the Junction of the Grand and Green Rivers of the Great 

Colorado of the West, in 1859, under the command of Capt. J. N. Macomb; 152 pages.

66 Preliminary Report of a Special Geological Party operating in Colorado and 

New Mexico, from Spanish Peaks to the South, field season of 1878, John J. Stevenson. Report of the Chief of Engineers for the year 1879, Part in, pp. 2249-2259.

66 Report upon Geological Examinations in Southern Colorado and Northern New 

Mexico during the years 1878 and 1879, John J. Stevenson. Report upon U. S. Geographical Surveys West of the One Hundredth Meridian, vol. m, Supplement, Geology, pp. 3-406. With atlas sheets. «

67 Geology, Mineralogy, and Mining Industry, F. V. Hayden. 7th Ann. Rept. U. 

S. Geol. and Geog. Survey of the Territories, pp. 15-82. With atlas sheets. See, also, 

8th Ann. Rept. U. S. Geol. and Geog. Survey of the Territories, pp. 19-58. With atlaa 

sheeta,
VAN HISS.] THE CORDILLERAS. 345

68 Abstract of Report on Geology and Mining Industry of Leadville, Lake County, 

Colorado, S. F. Emuions. 2d Ann. Rept. U. S. Geol. Survey for 1880-'81, pp. 201-290, 

2 plates. See, also, Monograph 12, U. S. Geol. Survey, pp. 45-52,58-60.

59 Geology of the Aspen Mining Region, Pitkin County, Colorado, Arthur Lakes. 

Biennial Report of the State School of Mines, Golden, Colorado, 1886, pp. 43-84.

00 Report on the Geology of the Northwestern Portion of the Elk Range, W. H. 

Holmes. 8th Ann. Rept. U. S. Geol. and Geog. Survey of the Territories, pp. 59-71.

61 The Coal Field of Crested Butte, Gunnison County, Colorado, Arthur Lakes. 

Annual Report of the State School of Mines, Golden, Colorado, 1885, pp. 111-136.

63 Report upon the Eagle, Grand, and Gutinison rivers, A. C. Peale. 8th Ann. Rept. 

U. S. Geol. and Geog. Survey of the Territories, pp. 73-180. With atlas sheets.

63 Geological Report on the Grand River District, A. C. Peale. 9th Ann. Rept. U. 

S. Geol. and Geog. Survey of the Territories, pp. 29-101. With atlas sheets.

64 Report upon the San Juan Region, F. M. Endlich. 8th Ann. 'Rept. U. S. Geol. 

and Geog. Survey of the Territories, pp. 181-240. With atlas sheets.

" Notes on the Geology and Mineralogy of San Juan County, Colorado, Theodore 

B. Coinstock. Trans. Ain. Inst. Min. Eng., vol xi, pp. 165-191.

66 The Geology and Vein-Structure of Southwestern Colorado, Theodore B. Cornstock. Ibid., vol. XV, pp. 218-265.

67 Geology of Colorado Coal Deposits, Arthur Lakes. Annual Report of the State 

School of Mines, Golden, Colorado, 1889, pp. 264.

68Geological Report on the San Juan District, W. H. Holmes. 9th Ann. Rept. U. 

S. Geol. and Geog. Survey of the Territories, pp. 237-276. With atlas sheets. 

69 Exploration of the Colorado River of the West and its Tributaries, explored in 

1869, 1870, 1871, and 1872, J. W. Powell, pp. 291.

70 Report on the Geology of portions of New Mexico and Arizona, examined in 1873, 

G. K. Gilbert. Report upon Geographical and Geological Explorations and Surveys 

west of the One Hundredth Meridian, vol. in, Geology, pp. 503-566. With atlas 

sheets.

7J Pre-Carboniferous Strata in the Grand Canyon of the Colorado, Arizona, Charles 

D. Walcott. Am. Jour. Sci., 3d ser., vol. xxvi, pp. 437-442, 484.

72 Study of a Line of Displacement in the Grand Canyon of the Colorado, in 

Northern Arizona, C. D. Walcott. Bull. Geol. Soc. America, vol. i, pp. 49-64.

73 United States Exploring Expedition during the years 1838,1839,1840,1841,1842, 

under the command of Charles Wilkes, vol. x, Geology, James D. Dana. Philadelphia, 1849, pp. xii, 9-756, 5 maps, and folio atlas of 21 plates.

74 Report .upon the Geology of California, P. T. Tyson. Senate Ex. Docs., 1st 

sess. 31st Gong., vol. x, No. 47, pp. 3-74. With a map.

76 Report upon the Geology of the Route, J. S. Newberry. Reports of explorations and surveys to ascertain the most practicable and economical route for a 

railroad from the Mississippi River to the Pacific Ocean, in 1853-'54, vol. vi, Part n, 

pp. 9-68.

76 Geological Report on Routes in California to connect with the Routes near the 

Thirty-fifth and Thirty-second Parallels, and Route near the Thirty-second Parallel, between the Rio Grande and Pimas Villages, explored by Lieut. John G. Parke 

in 1854 and 1855, Thomas Antisell. Ibid., vol. vn, Part n, pp. 1-204. With maps 

and sections.

77 Geological Report on Routes in California to connect with the Routes near the 

Thirty-fifth and Thirty-second Parallels, William P. Blake. Ibid., vol. v, pp. 370, 

part 2. With geological sections.

78 Report on the United States and Mexican Boundary Survey, made under the 

direction of the Secretary of the Interior, William H. Emory, vol. i, pp. 1-99, Part 

ii. See, also, Geology and Paleontology of the Boundary, James Hall. Ibid., pp. 

114, 115, 120, 121.

79 Geological Report, Dr. J. S. Newberry. Report upon the Colorado River of the
346 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BOLL. 86.

.West, explored in 1857 ami 1858, by Lieut. Joseph C. Ives. Washington, 1861, Part 

3, pp. 154.

80 Report of Progress and Synopsis of the Field Work, from 1860 to 1864, J. D. 

Whitney. Geological Survey of California, vol. i, Geology, pp. 498.

81 Report on the Geology of a Portion of Southern California, Jules Marcou. Report of Chief of Enginee rs for the year 1876, Part in, pp. 378-392.

82 Report on the Geological and M ineralogical Character of Southeastern California and adjacent regions, Oscar Loew. Ibid., pp. 393-408.

83 Geological Report on the portions of Western Nevada and Eastern California 

between the parallels of 39° 30' and 38° 30', explored in the field-season of 1876, A. 

R. Conkling. Report of the Chief of Engineers for the year 1877, part 2, Appendix 

H, pp.1285-1295.

84 Geolo'gical Report on portions of Western Nevada and Eastern California, including part of the Sierra Nevada Range, A. R. Conkling. Report of the Chief of 

Engineers for the year 1878, part 3, pp. 1589-1607.

85 Geology of the Quicksilver Deposits of the Pacific Slope, George F. Becker. 

Monograph 13 U. S. Geol. Survey, pp. xix, 486; 7 pi. and atlas of 14 sheets folio.

86 The Structure of a portion of the Sierra'Nevada of California, Geo.F. Becker. Bull. 

Geol. Soc. of America, vol. u, pp. 49-74.

87 Report upon the Geology of the Central Portion of Washington Territory, George 

Gibbs. Reports of Explorations and Surveys from the Mississippi River to the Pacific 

Ocean, in l853-'54, vol. i, pp. 473-486.

88Report on the Coal Fields of the East Coast of Vancouver Island, James Richardson. Rept. of Prog. Geol. Survey of Canada for 1871-72, pp. 73-100. Accompanied 

by a map.

89 On the Coal Fields of Vancouver and Queen Charlotte Islands, James Richardson. Rept. of Prog. Geol. Survey of Canada for 1872-73, pp. 32-65. Accompanied by 

a map.

90 On Explorations in British Columbia, James Richardson. Rept. of Prog. Geol. 

Survey of Canada for 1874-75, pp. 71-83.

91 OnExploration in British Columbia, A. R. C. Selwyn. Rept. of Prog. Geol. Survey 

of Canada "for 1875-'76, pp. 28-86; with a sketch map.

92 Geological and Topographical Notes on the Lower Peace and Athabasca Rivers, 

John Macoun. Ibid., pp. 87-95.

93 Report on Explorations in British Columbia, George M. Dawson. Ibid., pp; 

233-265.

94 Report on Exploration in British Columbia, George M. Dawson. Rept. of Prog. 

Geol. Survey of Canada for 1876-77, pp. 17-94. With a geological map.

95 Preliminary Report on the Physical and Geological Features of the Southern 

Portion of the Interior of British Columbia, G. M. Dawson. Rept. of Prog. Geol. 

Survey of Canada for 1877-78, pp. 1-173 B. With a map.

?fi Report on the Geology of the Country near the Forty-ninth Parallel of North 

Latitude west of the Rocky0 Mountains, from Observations made in 1859-'60, H. 

Bauerman. Rept. of Prog, Geol. and Nat. Hist. Survey and Museum of Canada for 

1882-'83-'84, pp. 3-42 B.

97 Preliminary Report on the Physical and Geological Features of that portion of 

the Rocky Mountains between Latitudes 49° and 50° 30', G. M. Dawson. Ann. Rept. 

Geol. and Nat. Hist. Survey of Canada for 1885, vol. i (new series), pp. 5-169 B. 

With a map.

98 Report on a Geological Examination of the northern part of Vancouver Island 

and adjacent coasts, George M. Dawson. Ann. Rept. Geol. and Nat. Hist. Survey of 

Canada (new series), vol. II, 1886, pp. 129 B. With a map.

99 Report on the Geological Structure of a portion of the Rocky Mountains, R. G. 

McConnell. Ibid., pp. 1-41 D.
VANHISE.] . .THE CORDILLERAS. 347

100 Report on the Geology of the Mining District of Cariboo, British Columbia, 

Amos Bowman. Ann. Rept. Geol. and Nat. Hist. Survey of Canada for 1887-'88, vol. 

in (new series), pp. 5-49 C. With maps.

101 Note on the Geological Structure of the Selkirk Range, George M. Dawsou. 

Bull. Geol. Soc. America, vol. n, pp. 165-176. See also Report on a portion of the 

West Kootanie District, British Columbia, 1889, George M. Dawson. Geol. and Nat. 

Hiat. Survey of Canada, Ann. Rept. (new series), vol. iv,pp. 28-40 B. With a map.
OHAPTEE VII.

EASTERN UNITED STATES. 

SECTION I. THE NEW ENGLAND STATES.

LITERATUKE OF MAINE.

JACKSON/ in 1837, observed granite, gneiss., and mica-schist at many 

localities. At one place schistose fragments occur in syenite, which 

indicates that the syenite has been thrown up in a melted state since 

the deposition and induration of the argillaceous and talcose slates 

included. Dikes very frequently cut the fossiliferous horizon.

HITCHCOCK2 (EDWARD) in 1837, describes a rock succession at Portland as consisting from the base upward of (1) granite; (2) gneiss; (3) 

talcose and mica-slates, with quartz-rock; (4) hornblende-slate; (5) 

limestone; (6) plumbaceous mica-slate; (7) pyritiferous mica-slate. 

The latter has the aspect of a graywacke-conglomerate, being filled 

with distinct rounded masses of quartz rock. It is really a mica-slate 

conglomerate. The series are in a vertical position and the whole are 

cut by greenstone dikes.

JACKSON,3 in 1839, includes in the Primary rocks of Maine the granites, gneiss, talcose slate, and argillaceous slate. The transition rocks 

are a great formation, which includes slates, limestones, fine graywackes, and coarse conglomerates. It is also fossiliferous. At one place 

mica-slate is thrown aside by intrusive granite.

HITCHCOCK 4 (CHAS. H.), in 1861, divides the unfossiliferous rocks 

into Stratified or Azoic and Laurentian. With the latter are placed 

granitic, trappean, and Archean rocks. The Azoic rocks, which may 

be in age Laurentian to Carboniferous, include gneiss, mica-schist, 

quartz-rock and conglomerate, j asper, siliceous slate, and hornstone. The 

quartz-rocks and conglomerates are associated. At one place a conglomerate has elongated pebbles which indent each other, which is 

evidence that they must have been in a plastic condition. Metamorphism may even produce granite and gneiss by aqueo-igneous fusion. 

The syenites containing fragments of schist and trap, described by 

Jackson, are believed to be metamorphosed conglomerates, the included 

pebbles of which have preserved their original shapes. The foliation 

of the rnetamorphic rocks generally correspond with the planes of stratification, but may cross the strata like cleavage planes. The trap dikes 

are believed to be eruptive.

348
U.S. GEOLOGICAL SURVEY. BULLETIN 86. PL .XI

- 39

UNCLASSIFIED PARTLY OR WHOLLY CRYSTALLINE ROCKS UNCLASSIFIED PRE-CAMBRIAN POST-ALGONKIAN

GEOLOGICAL MAP OF THE NORTHEASTERN STATES

SHOWING PRE-CAMBRIAN AND CRYSTALLINE RCCKS 

After M c Gee and Hitchcock

Scale TTuoo.ooo.
VAN HISB,] EASTERN UNITED STATES. 349

HITCHCOCK (CHAS. H.),5 in 1862, describes the rocks of the southern 

part of the state as granite and syenite, gneiss and mica-schist, saccharoidal Azoic limestone, quartz-rock, (Taconic), Eolian limestone, etc. 

Presumably the granite and syenite, the gneiss and mica-schist, and 

Azoic limestone are Primitive. In the Kennebec valley are found interstratified limestones and slates, the cleavage of which is almost 

transverse to the bedding, so that it is only possible to get at the true 

direction of lamination by following the limestone belts. At one place 

is an abrupt change from mica-schist to granite. A red conglomerate 

rests uncomformably upon a slate at Woodstock.

HITCHCOCK (CHAS. H.),6 in 1874, describes at Portland three groups 

of rocks, the oldest of which is the Huronian. In this system are green 

talcose schists, hornblendic schist, micaceous and plumbaceous schist, 

and other varieties. They are referred to the Huronian on the ground 

that such rocks are typical of this period, and continuity of mineral 

character indicates similarity of, age till otherwise proved.

HUNTINGDON,7 in 1878, describes the region about the headwaters of 

the Androscoggin river. The rocks are classified as Laurentian, Huronian, and Paleozoic. In the Laurentian is gneiss, containing limestone. In the Huronian are White mountain gneisses and schists, 

mica-schists, with staurolite, chloritic and whitish argillitic mica-schists, 

sandstone-schists, diabase, diorite with serpentine, argillitic micaschists with staurolite, and Bangely conglomerates. In the Eangely 

conglomerate, when freshly broken, every portion of it except the pebbles resembles in all respects the staurolitic schist. Going across the 

stratification are places where the pebbles are wanting, or have been 

so changed that they are not apparent, although locally the fragments 

of the conglomerate are a foot in diameter. Granite, diorite, and felsite are placed among the eruptive rocks.

SHALER,® in 1889, describes the rocks of mount Desert. , The island 

consists of a central mass of hornblende-granite and a succession of 

sedimentaries on the north and south sides. About the massive core 

are the following series: The Sutton island series of highly metamorphosed clay-slates, quartzites, bedded felsites, and' associated traps; 

the Cranberry island series, essentially the same as the Sutton island 

series, with many beds of volcanic ash; the Schooner head series of 

contorted argillaceous schists, shales, and the associated injected 

rocks; the Bar harbor series of thick-bedded flaggy slates and associated bedded felsites and quartzites, with numerous injections of 

igneous rocks; and the Bartletts island series of contorted schists, 

with frequent beds of quartzites, which often assume a gneissic aspect 

with the associated injections of igneous rocks. The great central 

mass of granite is said to be essentially a dike. In approaching the 

central granite the amount of granitic dike injections in the sedimentary series greatly increases, and in the sedimentary rocks are found 

numerous dikes of granite. No two of the various sedimentary series
350 PEE-CAMBRIAN EOCKS OF NORTH AMERICA. [BULL. 86.

are found superimposed upon each other, although there are at least a 

half dozen series which are regarded as representing different parts of 

the geological section. The aggregate thickness of the various sections 

is not less than 6,000 feet and may be one half more than this. The 

great part of mount Desert rocks are referred to the lower part of the 

Cambrian section, although the volcanic rocks of Cranberry island 

resemble deposits of similar nature at Eastport, Maine, which seem to 

be of Silurian age.

LITERATURE OF NEW HAMPSHIRE.

JACKSON,9 in 1841, in a general consideration of the geology of the 

state, states that granite is an igneous rock and is the foundation on 

which all the more recent formations rest. When it is found cutting 

other rocks, the intense heat has often metamorphosed the adjacent 

rocks for considerable distances. Eeposing directly on the granite is 

found gneiss, the origin of which is undetermined. By some geologists 

gneiss is considered a metamorphic rock; others suppose that its stratified structure is due to the crystallization in laminae and that it is 

merely the upper crust of granite. Above the gneiss are found micaslate, chlorite-slate, and argillaceous slate, which are regarded as 

metamorphic rocks. Slates and granite alternate with each other, and 

this is due to the subsequent intrusion of granite. There have been 

several periods of eruptions of trap dikes, as is shown by the manner 

in which they cut each other.

JACKSON,10 in 1844, gives many facts as to the distribution of the 

rocks, with numerous sectional profiles. Granite, syenite, porphyry, trap, 

basalt, and lava are regarded as eruptive rocks. As a result of outbursts and elevations the strata have been broken up, altered in position, and included between masses of molten gneiss and granite. In 

this way is explained the intercalation of masses of argillaceous slates 

in the primary series and the metamorphosis of the sedimentary deposits by igneous action.

BOGKERS, (HENRY D. and WM. B.),11 in 1846, state* that the assumption that the White mountains belong to the Primary series involves 

two errors: first, in assigning all the rocks to the gneissoid class; and, 

second, in supposing that none of the strata contain organic remains. 

The gorge of the Saco was closely examined. The rocks were found to 

have a stratified structure throughout, although in many cases approaching very close to granite. They are regarded as very highly 

metamorphic sandstones and slates. Associated with the crystalline 

rocks are semicrystalline sandstones which contain distinct fragments. 

In a shale are found fossils, which lead to the conclusion that the 

series represents the Levant or Matinal. The metamorphic beds are cut 

by beds and veins of syenitic granite, and the extremely crystalline 

character of the slates and sandstones is regarded as due to the igneous 

material. .
VAN HISE.] EASTERN UNITED STATES. 351

JACKSON, 12 in 1848, maintains that in the White mountains are numerous localities where fragments of slate are included in th^e granite 

which are not altered by heat beyond mere induration. -In New Hampshire numerous masses of older Silurian strata occur intercalated with 

the Primary rocks.

HITCHCOCK (C. H.) and HUNTINGS ON, 1:< in 1877, give a full account of 

the geology of New Hampshire. Hitchcock divides the pre-Paleozoic 

rocks of the northeastern United States into two divisions: first, the more 

ancient gneisses and granites; second, the area of hydromicaeeous and 

micaceous schists, which are termed Huronian. In the Paleozoic are 

placed great expanses of clay-slates. The first division, is divided into 

four parts: first and oldest, the Laurentian; second, the porphyritic 

gneiss and the various undetermined granites; third, the Atlantic; and 

fourth, the Labradorian. Among the Huronian is placed the Quebec 

group of Logan.

Huntington gives the geology of the Coos and Essex district. The 

Coos rocks, consisting of argillaceous schists, clay-slates, and micaceous 

sandstones, are supposed to belong to the fossiliferous series. The Huronian rocks are found east of the line limiting the Coos group. They 

consist of green chloritic rocks, in which the lines of stratification are 

obscure. Contained are greenish f'eldspathic sandstones, with intercalated bands of siliceous limestones. There are also here contained 

stratified diorites, diabases, and hornblende-rocks. The porphyry which 

occurs connected with the Coos and Huronian penetrates the rocks 

with which it comes in. contact, and the intrusive character cannot be 

doubted. Outcrops of granites and granitoid gneisses have a wide extent, a part of them being regarded as genuine eruptive granites since 

they intersect the schists in numerous veins and beds. The basic dikes 

are the latest of all, cutting the granites and intersecting the schists 

at many places.

Hitchcock gives the formations of the White mountain district in 

ascending order, as follows: (1) Porphyritic gneiss; (2) Bethlehem 

gneiss; (3) Berlin or Lake gneiss; (4) Montalbari group; (5) Franconia 

breccia; (6) Labrador system or Pemigewasset series of granites, ossi. 

pytes, compact feldspars, etc.; (7) syenite; (8) andalusite slates; (9) 

Pequawket or mount Mote granite. The three first are regarded as 

metamorphic, although the stratification is destroyed. Tbe Montalban 

group includes granitic gneiss, mica-schist, and quartzite. The granitic gneiss sometimes shows no visible mark of stratification, as in 

the Concord granite, although the whole is regarded as metamorphic. An unconformity is inferred between the Montalban schists 

and the porphyritic gneiss on account of the divergence in the strike 

of the two groups. Eruptive granite is found in the Moutalban schists. 

The Franconia breccia is placed later in the chronological scale than 

the Montalban group, because it is the impression of the author that 

he has seen Montalban fragments in this rock. The Labrador system
352 PEE-CAMBRIAN ROCKS OP NORTH AMERICA. [BULL. 86.

is considered as the probable equivalent of the Labrador system of 

Loganand Hunt. It includes the Conway granite, Albany granite, 

Chocorua granite, Ossipyte or Labradorite rocks, and various compact 

and crystalline feldspars or porphyries. The relations of the Albany 

granite and the Andalusite slate do not show that the underlying granites are certainly not sediments, although they have been so thoroughly 

metamorphosed as to have lost their lines of original bedding; but the 

evidence in favor of their eruption since the deposition of the andalusite 

slates4s increasing. The slates are twisted and broken in many places, 

the fragments being cemented together by a granitic paste; also, fragments of slate occur imbedded in the underlying granite. The Labrador group is found in seven areas. The Labrador rocks lie.unconformably upon the upturned edges of the Montalban gneisses, the 

discordance varying from 45° to 70°. Porphyry occurs in this system, 

which is regarded as intrusive. Syenite has quite a widespread occurrence. The andalusite slates are regarded as the equivalent of the Coos 

series, but they are similar to the Huronian system. The Pequawket 

series is regarded as late eruptives. The stratigraphic order in the 

White mountains is finally concluded upon as follows: (1) the Laurentian, represented by the Porphyritic gneiss and the Bethlehem 

group; (2) the Atlantic, consisting of the Lake or Berlin and Montalban gneisses, and the Franconia breccia; (3) the Labradorite; (4) the 

Huronian; (5), the Merrimac schists; (6) the Andalusite schist group; 

(7) eruptions of porphyry; (8) eruptions of the Conway, Albany'and 

Chocorua granites and syenites; (9) the formation of the mount Pequawket or mount Mote porphyritic breccia. This order is somewhat different from that stated at the beginning of the chapter. The Huronian 

barely touches the White mountain area. With it are placed certain 

quartzites which are lithologically like those of Canada. The Green and 

White mountain gneisses are regarded as Eozoic because they are a 

continuation of the Eozoic rocks of New Jersey and ISTew York, because 

they are bordered by quartzites which are of Cambrian age, which dip 

away from them, both to the east and west, because the Labrador series 

is present, and because fossiliferous Helderberg strata are found on 

both the east and west sides of the White mountains side by side with 

the metamorphic schists, the former containing fossils.

In the Ammonoosuc gold field of the Connecticut valley the following succession is found: (1) Laurentian, consisting of the Porphyritic 

and Bethlehem gneisses; (2) Atlantic gneiss, represented by the 

Lake division; (3) Huronian, embracing the Lisbon and Lyman groups 

and the auriferous conglomerate; (4) Cambrian clay-slate; (5) Coos 

group; (6) Swift water series; (7) Helderberg quartzites, slates and 

limestones. The Huronian formations embrace schists, conglomerates, 

the pebbles being sometimes flattened, quartzites, dolomites and jaspers.

In the area between Haverhill and Clarernont the subdivisions are
VAN H.SE.] EASTERN UNITED STATES. 353

as follows: (1) Bethlehem gneiss; (2) Huronian, with three or four 

subdivisions; (3) Cambrian clay slate; (4) Coos quartzites; (5) Coos 

slates and schists; (6) calciferous mica-schist; (7) eruptive granites, 

including the mount Ascutney area, which is partly composed of rocks 

older than Huroniau.

In the Connecticut valley district, between Clareuiont and Hinsdale, 

the succession is as follows, beginning with the lowest: (1) Bethlehem 

gneiss; (2) gneisses of the Montalbau series; (3) Huronian; (4) Coos 

quartzites; (5) Coos slates and schists; (6) calciferous mica-schist; (7) 

eruptive granite. The Coos quartzites and calciferous mica-schists are 

only semicrystalline rocks, all the thoroughly crystalline schists being 

placed with the pre-Caiiibrian. The thickness of the Huronian rocks 

in. New Hampshire is placed in the neighborhood of 10,000 feet.

Huutiugton gives the order of superposition of the rocks in the west 

part of the Merrimac district, as follows: (1) Porphyritic gneiss; (2) 

Bethlehem or Protogeue gneiss; (3) common or Lake gneiss; (4) ferruginous concretionary schist; (5) fibrolite schist, sometimesgneissie and 

passing into common mica-schist; (G) quartzites and quartz conglomerates; (7) intrusive rocks and veinstones. Hitchcock gives the order 

in the east part of the district thus: (1) Porphyritio gneiss; (2) Lake 

gneiss; (3) Moutalban series, including the Concord granite; (4) ferruginous schist; (5) Andalusite mica-schists, with coarse granite veins; 

(C) Eockingham mica-schist; (7) Kearsarge andalusite group; (8) Merrimac group, including a little clay slate. There are no eruptive rocks 

in this area of sufficient importance to find a place upon the map.

Hitchcock gives the succession in the Lake district, embracing the 

\Vinnipiseogeeiake and the flat country to the north, as follows: (1) 

Porphyritic gneiss; (2) Lake gneiss; (3) Moutalban. The eruptive 

rocks are more plentiful and varied, consisting of (1) Con way; (2) 

Albany: (3) Chocorua granites; (4) porphyry; (5) Pequawket breccia; (6) Labradorite diorite; (7) syenite; (8) granite, not allied to any 

of the foregoing.

The succession in the Coast district, including the southeast corner 

of the State, is as follows: (1) Porphyritic gneiss; (2) Lake gneiss 

(including the Laurentiau of Massachusetts); (3) Montalban; (4) Rockinghanigroup; (5) Merrimac group; (6) Kearsarge group; (7) Huroniau 

and Cambrian of Massachusetts. The unstratified rocks are the syenites of Exeter and Pawruckaway, inferior granites, and the well developed granites and porphyries of York county, besides a great many 

trap dikes along the coast.

In considering the principles of classification, as guiding principles 

it is premised that in this field are inverted flexures and dislocations of 

the strata. Also that formations of the same mineral composition in 

one part of the field may be identified with those of like composition in 

another part of the field, as, for instance, the porphyritic gneiss in 

thirty areas has feldspar crystals very conspicuous for their size. All 

Bull. 80 23
354 rilE-CAMBKIAX ROCKS OF NORTH AMERICA. [BULL. 80.

those areas are assumed to be identical in age, and in placing the relative positions of the intervening- groups this is relied upon for a starting point. The general order of succession for New Hampshire, from 

the base upward, is, Porphyritic gneiss; Bethlehem gneiss; Lake and 

Montalban series; argillaceous, talcose, hydromicaceous and calcareous 

series; Labrador series (present in New Hampshire, limited in amount); 

'A'arious types of mica-schists. Andalusite slate in this mica-schist formation lies uncoiiformably upon the Montalban at mounts Monadnock and Kearsarge. The principal eruptive masses are the Con way, 

Albany, Chocorua granites, syenites, other granites, and labradorite, 

diorites and dolerites. The granites cut rocks as high as the Coos 

group. The Porphyritic gneiss and the Bethlehem group are referred 

to the Laurentiau. The Lake gneiss can not easily be assigned. The 

Montalban certainly is not characteristic of the Laurentian, but all of 

the preceding are regarded as underlying the Huronian. It is thus 

concluded to place the Porphyritic, Bethlehem, and Lake gneisses with 

the Laurentian, leaving the position of the Huronian and Montalban to 

be settled by other considerations.

The Huronian is divided into two divisions, the upper chloritic, and 

the lower quartzose and feldspathic. The greenstones seem to be 

closely allied to the upper Huronian and the porphyries to the lower 

division, and to this may belong the supposed eruptive porphyries of 

the White mountains. The Merrimack, Eockingham, and Kearsarge 

mica-schists are somewhat related to the Huronian, as well as to the 

Cambrian. They.are all referred doubtfully to the Paleozoic system. 

The doubtful Paleozoic is placed at 11,600 feet thick: the Upper Huronian, 12,129 feet; Lower Huronian, not estimated; Montalban, 13,700; 

Laurentian, 34.900. The Labrador system if present in New Hampshire is in very limited amount. Certain of the labradorites are surely 

injected dikes, and hence it is doubtful whether the Waterville area 

really represents the Labrador system of Canada.

HAWES, 14 in 1878, regards the diabases, diorites, ga,bbros, felsites, 

granites, and syenites of New Hampshire as eruptive rocks. Some of 

them may have been produced by the fusion of sediments, but however 

this may be, they have all been in a molten condition and been free to 

crystallize. There are beds of granite which are unconformable with 

the associated stratified rocks; there are granites filling well denned 

dikes; there are granites which so far as can be seen are entirely devoid of structural relations; there are granites which are mixed with 

other rocks, or which hold huge fragments of other rocks inclosed in 

their masses. All these features are often repeated. Among the crystalline schists are placed gneiss, mica-schist, argillitic mica-schist, and 

quartz- schist. The gneisses, like the granites, are believed to be of 

eruptive origin, or at least to have acted like an eruptive rock, the 

lamination being an induced structure which may or may not correspond with original bedding in case they are completelv metamor-
VAN HISE.J EASTERN UNITED .STATES. 355

pbosed material.' The gneisses in their minerals, inclusions, and microscopic characters are like granites, and pressure may have been as 

effective in producing lateral movements and forming foliation in a 

plastic mass as sedimentation. If the stratification of the gneiss is 

then regarded as an induced structure it would not follow that the 

stratification, should correspond with the original bedding, and even if 

the lamination does correspond with the plane of the strata, the lamination can not be referred to stratification of sediments, for the cleavage 

of the adjacent rocks may also be due to pressure and be different from . 

the piane of bedding. The greenstones, including metamorphic diorite, 

quartz-diorite, and arnphibolite, are regarded as metamorphosed sedimentary rocks. These have marked lithological distinctions from the 

fresh basic rocks recognized as eruptives. The clay-slates and quartzschists are semicrystalline rocks. The slaty cleavage and bedding 

are sometimes discordant.

HAWES,15 in 1881, describes the Albany granite as penetrating and 

metamorphosing the schists, and as having a porphyritic structure near 

its contact with them, and it is therefore concluded to be intrusive.

HITCHCOCK, (CHAS. H.) 16 in 1890, regards the oval granitoid areas 

occurring in the White mountains, about which occur foliated rocks 

with an anticlinal quaquaversal arrangement, as the oldest known or 

fundamental rocks of the region which are remains of an ancient 

archipelago.

WILLIAMS, 16 in 1890, with the same facts before him gives an exactly 

opposite interpretation to Hitchcock, that is, that the central granites 

are younger intrusive masses.

LITERATURE OF VERMOKT.

ADAMS, 17 in 1845, divides the older rocks of Vermont into Primary 

strata and Paleozoic rocks. The Primary system is highly crystalline and destitute of fossils. It is divided into argillaceous slate, 

calcareo-mica-slate, mica-slate, talcose slate, Green mountain gneiss, 

gneiss proper, which however does not represent the order of superposition as the strata are involved in great confusion. The marbles of 

the state are divided into three systems, Primary, Taconic and New 

York. There are few Primary marbles in the state. The Taconic 

marbles occur throughout the range of limestone from Massachusetts to 

the north part of Madison county. The Taconic system includes roofing slate, Taconic slate, Sparry limestone, rnagnesian slates, Stockbridge 

limestone, and granular quartz-rock.

ADAMS,18 in 1846, includes the Taconic and Primary systems of his 

previous reports under the general term Azoic stratified rocks, as 

simply expressing the fact of the absence of organic remains, for jt is 

not to be assumed that the Azoic Taeonic rocks are more ancient than 

the Paleozoic, and the same remarks may be said of the so-called Primary rocks, not a small portion of which may be as metamorphic and
356 PRE-CAMBRIAN ROCKS OP NORTH AMERICA. [BULL.86.

recent as the Champlain rocks. In the Green mountains are quartzrock, gneiss, talciferous limestone, quartz-gneiss and limestone which 

are supposed to be Taconic. Dikes of greenstone (nit through all the 

divisions of the stratified rocks and are therefore more recent than any 

of them.

ADAMS, 19 in 1847, gives additional details as to the rock occurrences 

in particular localities.

THOMPSON,20 in 1856, states that the Green mountains form the center 

of an anticlinal axis, the dips increasing both east and west from the 

principal summits. Slates, schists and quartzites are found which 

contain a tew obscure fossils, and are referred to the Taconic system.

HITCHCOCK (EDWARD),21 in 1861, divides the rocks in general into 

Stratified or Aqueous and Unstratified or Igneous. With the latter 

are placed granitic, trappean and volcanic rocks. The former are, sub-* 

divided into Fossiliferous and Unfossiliferous, or Azoic. In this latter 

division are placed clay-slate, quartz-rock, mica-schist, talcose schist, 

and chlorite-schist, steatite or soapstone, serpentine, hornblende-schist, 

gneiss, and crystalline limestone. The important practical, question 

with respect to the metamorphic rocks is, what was the original rock 

from which the metamorphosed deposit was derived? In not a few 

instances so complete has been the metamorphism that it can not be 

told whether the rock belongs to the oldest of the crystalline rocks or 

is earlier than the SilurmiL or Cambrian. While the degree of metamorphism gives no clue as to the age of the rocks, from other evidence \t 

is probable that most of the highly metamorphosed rocks of Vermont 

are altered Devonian and Silurian. In the western part of the state, 

and especially tha/t part of New York that lies southwesterly, are found 

these fossiliferous rocks but little altered, and these form, a starting 

point for the Green mountain rocks and those farther east,

Metamorphism is made to apply to any transformation of any kind 

of rock into another. At Newport, Ehode Island, East Wallingford 

and Plymouth, Vermont, are found schist-conglomerates in which the 

pebbles are elongated very much in the direction of their strike. They 

are flattened, but not so strikingly as elongated; they are in den ted deeply 

into each other; they are sometimes a good deal bent; they are cut 

across by parallel joints and fissures. At times the process has gone 

so far as to merge the pebbles together, and as to scarcely present the 

appearance of ordinary pebbles. If the talcose conglomerate schist is 

looked at on the edge corresponding to the clip, nothing is seen but 

alternate folia of quartz and ta.lc and mica, and the rock would be pronounced a good example of a talcose-schist. But a fracture at right 

angles reveals the flattened pebbles, and shows that their edges are 

what have been, regarded as folia. If the process of flattening was 

carried a little farther no evidence would remain that they were ever 

pebbles. How extensively the process has been carried through, thus 

producing schists and gneisses from conglomerates, in the Green nioun-
VAN IIISR.] 'EASTERN UNITED STATES. ' 357

tains, is unknown. No examples have been found of decided pebbles 

in a gneiss.

At Whately, Massachusetts, on Ascntney, and at Barnet and Granby, 

Vermont, are conglomerates which, have as a matrix granite and porphyry. The granite sometimes passes into syenite. At Ascutney the 

syenite abounds in black rounded masses which are for the most part 

crystalline hornblende and feldspar, and are probably transmuted pebbles. At Granby the pebbles, manifestly rounded, are either mica-schist 

or white almost hyaline quartz, just such as form the pebbles in the 

conglomerates at Wallingford and Plymouth, and the base is a finegrained syenite, passing sometimes almost into mica-schist. A pebble of hornblende-schist is also sometimes seen. In bowlders of this conglomerate found at Northampton, Massachusetts, and probably derived 

from Whately, the most abundant pebbles are those of the brown sandstone, considerably metamorphosed and fattened. Those of hornblende-schist are common. Sometimes they are merely crystalline hornblende, not foliated generally, however, but mixed with some feldspar, 

and they may become syenite, and are frequently porphyritic by distinct crystals of feldspar. The cement is syenite, often more hornblendic than usual. When the pebbles are highly crystallized they 

become so incorporated with the matrix that it is difficult to separate 

them with a smooth surface, and if we are not mistaken they pass insensibly into those rounded nodules, chiefly hornblendic, so common in 

syenite, especially that of Ascutney. These occurrences are regarded 

as proof that the completely crystalline granular matrix is a metamorphic rock.

The pre-Potsdam rocks of Vermont are called Laurentian or Hypozoic, 

although it does not follow that they are not equivalent with the fossilil'erous series elsewhere. It is only believed that if fossils once existed 

in them they have been obliterated. Of the Hypozoie rocks, Vermont 

contains, so far as known, only a small belt, which is the eastern edge 

of an immense development of the same in New York. These are referred here because there seems to be a discordance in the stratification 

between these rocks and the Lower Silurian, to which they are adjacent. 

The oldest of the Paleozoic series lies directly upon the Hypozoic at least 

at one point. As we approach the Green mountains, metamorphism 

has so nearly destroyed the fossils that the identification of the strata 

becomes extremely problematical, until at-length the clue is lost entirely 

and the age of the formations can only be conjectured; hence they are 

distinguished mainly by lithological grounds and are grouped into a 

third class, Azoic rocks. Probably most of the Azoic rocks of Vermont 

will be found to be more recent than the Laurentian of Logan. The 

fossiliferous rocks are sometimes found under those that are more crystalline and nonfbssiliferous, and these cases are thougl.it to be the result 

of inversions. Certai n great thicknesses of schists of uniform character 

are regarded as folded several times so as to be vertical, because other-
358 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. so.

wise the thickness of the series would be enormous. The talcose conglomerates, talcoid schists, Georgia group, etc., are referred to the 

Potsdam and later formations. The Georgia group and sand-rock may 

be possibly Primordial. The talcose conglomerate is placed as a continuation of the Quebec group and Sillery sandstones of Canada. The 

Taconic system is regarded as having an extension into Vermont, and 

to it are referred the black Taconian roofing slates, Sparry limestone, 

magnesian slate, Stockbridge limestone and granular quartz rock, with 

associated talcose beds, the thickness of the whole being 25,200 feet.

It is supposed that the chief action of metaniorphism was in the 

Laurentian system and the cases of subsequent thorough alteration exceptional. The theory of the Laurentiau age of the Azoic rocks of New 

England and that of the Cambrian age of the Taconic system stand or 

fall together'. The Taconic system is regarded as older than the Lower 

Silurian and newer than the Laurentian, because it underlies the Silurian, because it is immensely thicker, and because the fossils which it 

contains are different from those of the Silurian.

HITCHCOCK, (CHAS. H.),22 in 1861, gives a lithological treatment of 

th e Azoic rocks of Vermont. They are divi ded into the following groups 

which are described in detail: Gneiss, hornblende-schist, mica-schist, 

clay-slate, quartz-rock, talcose sclust, serpentine and steatite, and saccharoid limestone. Cleavage has a widespread occurrence, although it 

is believed that the strike and dip of lamination and stratification generally correspond. The granite-gneiss approaches so near to granite 

that in hand specimens the two rocks can not be distinguished from 

each other. The granite of the two Ascutneys seems to have cut across 

the strata of the calciferous mica-schist quite a distance into the gneiss, 

although the granite is regarded as of metamorphic origin. Clay-slate 

often passes by insensible gradations into mica-schist, which is regarded as a modified fragmental rock. Associated with the talcose 

schists and constituting an integral part of the formation are clay-slate, 

gneiss, quartz-rock, sandstones, and conglomerates. Igneous rocks, 

both trap and granite, are also associated with this formation.

HITCHCOCK, (EDWABD),M in 1861, considers in detail the relations of 

the granitic to the other rocks and considers the origin of the granite. 

This rock is found inter stratified with slate, limestones and mica-schists 

in many localities. At the "Narrows," in the northern part of Coventry, the number of alternations is very large, the thickness of the different layers of granite varying from 1 to 7 feet.

The conglomeratic syenites of Whately, Massachusetts, and Ascutney, 

Granby and Bar net, Vermont, which, contain fragments, are described 

in detail. These may be described as conglomerates whose cement is 

syenite, or a syenite through which is scattered pebbles mechanically 

rounded. Generally the pebbles are more or less metamorphosed and 

sometimes almost converted into syenite subsequent to their introduction. In their present state white quartz, mica-schist, hornblende-schist,
VAV mat!.] EASTERN UNITED STATES. 359

and hornblende have been noticed. At Ascutney all traces of stratification in the conglomerate are lost and it passes first into an imperfect 

porphyry and then into a granite without hornblende in the same contrillions mass. Where the conglomerate is least altered it is made up 

almost entirely of quartz pebbles and a larger amount of laminated 

grits and shales, the fragments rounded somewhat, and the cement in. 

small quantity. The fragments are sometimes metamorphosed to micaschist. The conviction can not be resisted that the granitic rocks of 

this mountain are nothing more than conglomerate melted down and 

crystallized. At Granby the bowlders are of all sizes, from a few hundred pounds to 50 to 60 tons. They cover many acres, are associated 

with those of contorted mica-slate, quartzose granite, and many other 

varieties common in the region.

At several localities in Vermont, Craftsbury, Northfteld, New Fane, 

Proctorsville, and Stanstead, just beyond the Canada line, is a remarkable variety of white, fine grained, highly feldspathic granite which contains scattered through its face numerous spherical or elongated and 

somewhat flattened nodules of black mica from half an inch to 2 inches 

in diameter. They are usually more or less flattened and have a shriveled appearance like dried fruit. In solne cases the concretions occupy 

more tl^an half the mass. These concretions have sometimes been called 

petrified butternuts. The rock is regarded as produced by the metamorphism of a stratified rock.

Veins of granite are found to cut syenite, schist, gneiss, and limestone, 

in a most intricate manner at many localities. Sometimes there are 

several generations of granite veins. The foregoing facts lead to the 

conviction that the granite acts essentially like a liquid mass, but it is 

regarded as the product of aqueo-igneous fusion rather than dry fusion. 

Also it is believed that for the most part the granites have formed in 

situ, their material being furnished by the sedimentary rocks, hence 

they are called metamorphic. As evidence that they are metamorphic 

is the fact that it is often difficult to tell where a gneiss ceases and a 

granite begins. It is sometimes found, where granite masses come in 

contact with stratified rocks, that the latter have been more or less 

disturbed and broken, but only to a limited extent and often not at 

all. In many cases also the adjoining strata have suffered mechanical 

displacement, such as the forcible injection of melted matter would produce. For a considerable distance around the granitic masses also, 

the strata are frequently indura,ted and metamorphosed as if by heat, a 

fact that seems to decide the question of the emanation of much heat 

from granitic foci. The granites are more abundant in the crystalline 

than in. the fossiliferous series, in fact it is uncertain whether any occur 

in rocks which bear fossils, although they are found in those which are 

regarded as the equivalent of the Devonian. The granite is most common in gneiss and mica-schist, less so, especially in the form of veins, in 

clay-slates, and least of all in talcose schist. In the stratified rocks
3(50 PRE-CAMBETAN ROCKS OF NORTH AMERICA. !"" ' «« 

cleavage and foliation occur, while joints are found both in the stratified 

and unstratified rocks.

THOMPSON,24 in 1861, describes the greenstone or trap dikes of parts 

of Vermont. These are found to cut all the other rocks at many localities. Besides these there occur calcareous dikes, veins and dikes ol 

quartz, and metallic veins.

HITCHCOCK, (CHARLES H.),25 in 1861, gives detailed descriptions of 

sections in Vermont. The relations of the Ascutney syenite to the 

stratified rocks is again described. Upon examining the ledges immediately contiguous to the granite, most powerful marks of alteration by heat are found. Everywhere in approaching the syenite it is 

surrounded from a quarter to half a mile with indurated schists that 

ring like pot metal when touched with a hammer, and the lime-rock 

that is usually arranged in separate strata, seems to have become a, 

constituent part of each stratum, the whole rock resembling the compact vitrified quartz Avest of the Green mountains. Often crystals of 

staurotide, and perhaps scapolite, are formed in the schist by the heat. 

In. the west part of the larger mountain there are enormous veins 

crawling round in all conceivable directions in former crevices among 

the schists. This syenite is full of nodules of hornblendic masses, 

which look in some cases much like pebbles. They are probably concretionary, and are all allied to the concretions of black mica in granite 

at Craftsbury and elsewhere.

HALL (S. E.) ? 2G in 1861, gives many details as to the geology of northern 

Vermont. The granites are here particularly abundant. The occurrences are such as to lead to the conclusion that they are eruptive and 

that in their eruptions the fragments which are there contained have 

been caught from the strata cut. As evidence that the granite has 

been thrown up since the mica-schists were formed are cited the facts 

that the slates on the borders of the granite furnish unmistakable signs 

of contortion, and in some instances of change both in the direction of 

the strata and dip. In more than one instance, granite is found overlying the calcareous mica-slates, and in one instance, at Derby, eucrinite limestone occurs below granite. In many places jointed granite 

is found between the strata of slates, conformable to them, and in other 

instances, in dike form, crossing the strata at a large angle. Fragments of the older slates are, in many places, found imbedded in masses 

of granite, and retain the characteristics of the slates, without any 

essential change. Nodular granite, containing masses imbedded like 

plums in a pudding, run from Memphremagog lake through Derby, 

Brownington, Jrasburg, Craftsbury, and Calais.

HITCHCOCK (CHARLES H.),27 in 1868, gives the following succession 

for the rocks of Vermont: Uiistratified rocks, including granites, syenite, protogine, with the traps and porphyries; Eozoic system, including Laurentian gneiss of West Haven and the Green mountain gneiss j 

Paleozoic system, in which are placed the Georgia slates, the talcose 

conglomerate and schists, the mica-schists and other formations.
VAN msG.1 EASTERN UNITED STATES. ' 361

Mum',28 in 18G8, states that there is no evidence of the existence in 

Vermont of any strata, except a small spur of Laurentian, lower than 

the Potsdam formation. The so-called middle and lower Taconic is in 

part Potsdam and in part Utica, Hudson river, and Quebec:

McCoRMiCK,29 in 1887, describes the inclusions in the granite of 

Oaftsbury. The inclusions are spheroidal or elongated nodules of biotite 1J to 2 inches in diameter, and sometimes 4 inches long, cemented 

with quartz, which by Hitchcock were compared to butternuts. The 

line of contact between the inclusion and the rock is usually rather distinct, it being possible to extract the former, leaving alining of biotite. 

It is concluded that these nodules indicate the igneous origin of the 

granite because not capable of being formed from aqueous solution, or 

by metamorphic action.

LITERATURE OF MASSACHUSETTS.

HITCHCOCK (EDWARD),30 in 1818, divides the Primitive rocks of a section of Massachusetts on the Connecticut river into syenite, granite, 

argillite, alternating with mica-slate, siliceous slate, and chlorite-slate.

DEWEY,31 in 1818, states that the country of the Taconic range and 

Saddle mountain is principally Primitive. Granite is found on both 

sides of Hoosac and Pownal mountains. Gneiss, and mica-slate arcfound on the Hoosac and Saddle mountains. The Taconic range is com 

posed principally of a talcose or soapstone slate, but quartz, granular 

limestone, and argillaceous slate are found. Quartz occurs on Stone 

hill, above which is argillaceous slate. Granular limestone occurs on 

both sides of the Hoosac. Argillaceous slate occurs in the valleys connected with the limestone.

DEWEY,M in 1820, finds the section from the Taconic range at Williamstown to the city of Troy to consist of chlorite-slate, graywacke, 

and argillaceous slate, this being the order of succession. The strata 

all incline to the east from 10° to 40°, the general inclination being 20° 

or 25°.

HITCHCOCK (EDWARD),M in 1823, describes granite as occurring at 

many localities in the region contiguous to the Connecticut river. It 

sometimes shows a tendency to stratification, which at Southampton is 

in beds in the mica-slates, at Bellows falls grades into mica-slate, and 

frequently veins of it cut the strata. These veins divide and subdivide 

like the top of a tree. In this region a.re also found gneisses, hornblendeslate, mica-slate, talcose slate, chlorite-slate, syenite, x^rimitive greenstone, argillite, and limestone, all of which are referred to the Primitive. 

The gneiss is the most abundant rock, and often alternates with micaslate and passes into it. The dips of the layers are from.20° to 90° to 

the east. At Hatfield, by following up the syenitic ridge, a rock is 

found which contains n umerous imbedded masses of other primitive 

rocks, and these imbedded fragments are almost uniformly rounded and 

are often so numerous as to make the rock appear like a real secondary
362 PRK-CAMBRIAN ROCKS OF NORTH AMERICA. LBUM.. an.

conglomerate. Thus we have a really conglomeratic syenite. The primitive greenstones are distinguished from the secondary because the latter are more coarse and crystalline.

DEWEY,34 in 1824, in a sketch of the geology of western Massachusetts, divides the principal rocks into granite, gneiss, mica-slate, granular limestone, argillaceous slate, quartz-rock, transition limestone, and 

graywacke, mica-slate being the more abundant rock. The granite is 

not stratified, and must be considered as beds or veins rather than a 

continuous rock like the mica-slate. In the town of Windsor is a conglomeratic mica-slate.

NASH,35 in 1827, finds the rocks of Hampshire county to include granite, mica-slate, micaceous limestone, hornblende-rock, talcose slate, Old 

Bed sandstone, etc. The limestone often alternates with mica-slate, and 

frequently passes into it by insensible gradations. It is oftentimes garnetiferous. The granite veins are of all sizes up to 3 or 4 feet, cut the 

rocks in every possible direction, and intrude granite as well as the 

mica-slate.

HITCHCOCK (EDWARD),36 in 1833, divides the rocks of Massachusetts 

into stratified and unstratified. Below the New Bed sandstone in. the 

former are graywacke, argillaceous slate, limestone, scapolite-rock, 

quartz-rock, mica-slate, talcose slate, serpentine, hornblende-slate, and 

gneiss. The unstratified are greenstone, porphyry, syenite, and trap, 

each of which is discussed. Among the agents which have consolidated 

the rocks heat is the predominant one, although chemical action has 

played an important part. The mica-slates have been mechanically 

deposited in water, and subsequently subjected to such a degree of 

heat as to enable their materials to enter into a crystalline arrangement 

without destroying their structure. The granite is supposed to have 

resulted from the melting down of other rocks. Where it is completely

melted, granite results; where partially fused, granite-gneiss is found; 

while another portion might be converted into porphyritic gneiss and 

another into schistose rock. This theory explains the gradation of 

gneiss into granite and the crystalline and porphyritic structure of the 

gneiss. The unstratified rocks are all igneous. They occur in irregular protruding masses in the forms of veins of various sizes and as 

overlying masses. In cases in which they exist interstratified with 

other rocks, an examination shows that such interlaminated masses 

are always connected with an unstratified mass, and are merely veins 

which for a time coincide in direction with the strata. The syenite 

quarries of Sandy bay, cape Ann, have a parallel lamination, but as 

these grade into an unstratified syenite they are considered as examples 

of concretionary structure on a large scale rather than as a result of 

real stratification.

HITCHCOCK (EDWARD),37 in 1841, in a systematic account of the 

Geology of Massachusetts, divides the rocks below the New Red sandstone into the following classes: Graywacke, inetamorphic slates, argil-
VAN ursK.] EASTERN UNITED STATES. 363

laceous slate, limestone, quartz-rock, mica-slate, talcose slate, serpentine, hornblende-slate, gneiss, greenstone, porphyry, syenite, and granite. 

From the graywacke to the gneiss, this is the order of occurrence. 

The greenstone, porphyry, syenite, and granite are regarded as eruptive. At Bellingham is a remarkable metamorphic rock, which is a 

distinct mica-slate and a no less distinct conglomerate. In this formation is also placed aggregates of porphyry, which is a coarse 

breccia or conglomerate, chiefly made up of fragments of porphyry 

reunited by a cement of the same material, and sometimes almost 

reconverted into a compact porphyry. Flinty slate, chert, and jasper 

are simply the ordinary slate which have been changed to their unusual 

condition by the proximity of granite, porphyry, or trap. The clayslate is entirely destitute of organic remains, as is also the graywacke. 

The limestones are-water-deposited stratified rocks metamorphosed

by heat. The mica-slate is generally associated with gneiss, but also 

occurs associated with all other rocks at least as high as the argillaceous 

slate. Hornblende-schist and greenstone-slate, a single formation, are 

tentatively regarded as metamorphosed from ordinary argillaceous rock 

by the action of heat. Gneiss is often much folded and curved, is cut 

by veins of other rocks, but is regarded as generally regularly stratified.

At Whately occurs a peculiar conglomeratic syenite. The syenite is 

generally found between the granite and metamorphic rocks and may 

be due to the conversion of the granite into syenite or else to the eruption of the syenite at a different epoch. The pseudo-stratification of 

granite is regarded as due to concretionary action on a gigantic scale. 

The granite cuts and is inter stratified with all the stratified rocks and 

certain of the other eruptives in the most intricate fashion.

In Massachusetts are six systems which a.re unconformable and succeed each other in age. These are as follows: The Oldest Meridional 

system, the Northeast and Southwest system, the East and West system, Hoosac mountain system, the Bed Sandstone system, the Northwest and Southeast system. In western Massachusetts, from Hoosac 

mountain to the Taconic range, a powerful force has folded the strata 

so that in many cases they have actually been reversed.

LTELL,38 in 1844, describes the plumbago and anthracite in the 

mica-schist near Worcester. This is in the immediate neighborhood of 

masses of granite and syenite, the character of the plumbago and 

anthracite being due to this local metamorphosing effect and to more 

general chemical or plutonic action. The difference i n. dip of these rocks 

from the nearest Carboniferous of Rhode Island and Massachusetts 

is no evidence that they are not equivalent and the graphite metamorphosed organic material.

RoaERS,39 in 1857, describes Trilobites belonging to the Paradoxides 

as occuring in the metamorphic beds of eastern Massachusetts at Braintree, which shows that these ancient and highly altered sediments are 

the base of the Paleozoic column.
364 PRE-OAMBRIAN ROCKS OF NORTH AMERICA. [nuu,.8(i.

HITCHCOCK, ((J. II.),40 in 1859, describes the rocks Ironi Green field to 

Claremont, Massachusetts, as having the following order: Micaceous 

slates and schists interstratified with siliceous limestone, mica-slate, 

hornblende-slate, mica-slate iuterstratiiied with limestone, and, lastly, 

calcareo-mica-slate. The dips as far as the West Shelburne falls gneiss 

are to the east; at this latter point it is to the west. The whole is regarded as an anticline.

GREGORY,41 in 1862, describes Marblehead as consisting mainly of 

the Primitive formation. The northern part of the peninsula is greenstone, intersected by dikes of the same rock. In the southern section 

syenite contends with the greenstone for supremacy, for here the .two 

rocks are thoroughly intermingled. The deposits of greenstone, syenite, 

and porphyry are for the most part distinct, although occasionally the 

greenstone grades into the syenite.

JACKSON, 42 in 1866, gives the following section at the base of South 

mountain, at Chester, Massachusetts, from the base upward: Hornblende rock, magnetic iron ore, emery bed, granular quartzite, chloriteslate and talc-slate, crystallized talc, talcose slate rock, soapstone or 

talcose rock, mica-slate. At North mountain, separated from South 

mountain by a branch of the Westville river, the section is as follows: 

hornblende rock, magnetic iron ore, emery 7 feet, hornblende rock, 

chlorite-slate, magnetic iron ore 6 feet, talcose slate, magnetic iron ore 

6 feet, mica-slate.

SHALER, 43 in 1871, in a consideration of the rocks in the vicinity of 

Boston, states that there can be no doubt that the syenites of eastern 

Massachusetts are the oldest rocks found in the region. The quarries 

at Quincy show planes of separation in the syenite which can be only 

referred to stratification, despite the opinion generally entertained that 

the rocks are of igneous origin. This is evidenced by the fact that in the

deeper portions of the syenite the bedding is imperfect and gradually 

passes toward the exterior of the rock into a more laminated phase. 

The first rocks of unquestionably sedimentary origin lie north of Quincy 

and consist of bedded sandstones approaching quartzite. This series 

is fossiliferous. The alteration of the bedded quartzite at Hayward 

landing is so great that the rock has assumed something of the appearance of a gneiss. In 'addition to these rocks, in the vicinity of Boston 

are the Eoxbury conglomerate and the Cambridge slates. In the latter are found evidences of organic life in tlie presence of numerous indistinct impressions of fucoids. It is believed that the Cambridge 

slates and the lioxbury conglomerate belong to the same great series 

of beds. As there is a coincidence in the direction of dip it is thought 

they all may eventually be found to be a part of the same series of beds 

as the Braintree. The slates have a perfect cleavage in the plane of 

stratification in some places. Over both the slates and conglomerates 

are outflows of amygdaloid. 

JACKSON,44 in 1871, states that there is an insensible passage from
VAX HISB.I EASTERN UNITE!) STATES. 365

tl ie syen te into the greenstone porphyry. The obscurely stratified rocks 

on the border of the great syenite mass at Quincy prove the igneous 

influence of the eruptive syenite upon the upturned strata which it had 

elevated by its protrusion.

DANA,45 in 1872, maintains from the descriptions of full sections that 

at Great Barrington is a conformable succession of quartzites, limestones, mica-schists and gneisses. The layers of quartzite are found 

along the strike to change to mica-schist and gneiss. This series, many 

of them later in age than the Stockbridge limestone, is similar to the 

Green mountain series, which has been regarded on lithological evidence 

to be pre-Silurian. The Stockbridge limestone, on fossiliferous evidence, 

is found to be either Silurian or younger. It appears that lithological 

evidence is a very uncertain test as to geological age, as crystalline 

rocks are found later than the Stockbridge limestone j as quartzite 

changes into mica-slate, schist or gneiss, these into hydromica-slates, 

and these into chloritic mica-slate.

HUNT/6 in 1872, states that the rocks seen in. the vicinity of Boston 

consist of three classes, crystalline stratified rocks, eruptive granites, 

and unaltered slates, sandstones, and conglomerates. The crystalline 

stratified rocks include the felsite-porphyries, nonporphyritic and jasper-like varieties, andporphyritic syenite; while the second division includes dioritic and chloritic rocks, sometimes schistose, and frequently 

amygdaloidal. These rocks are penetrated by intrusive granites, generally more or less hornblendic, the syenites of Hitchcock, and others. 

At several places the phenomena of disruption and inclosure of broken 

fragments of rock in the granite are well seen, the lines of contact being always sharp and well defined. The third class, consisting of the 

unaltered argillites of Brain tree, containing the Primordial fauna, were 

found to rest directly upon the hard porphyritic felsite of the ancient 

series, the line of demarcation being very distinct. At other places 

reddish granulites directly underlie the black argillites, and in several 

places quartzites with conglomerates are observed in contact with the 

old dioritic and epidotic rocks. The Eoxbury conglomerate contains 

pebbles of the felsite-porphyries, diorites, and intrusive granites of the 

older series, besides fragments of argillaceous slate.

BuKBANK,47 in 1872, states that the bands of crystalline limestone 

that occur in the granitic gneiss which extends in a southwesterly direction from near the mouth of the Merrimac river, supposed to contain 

Eozoon, are not true stratified rocks, but are subsequent deposits of a 

vein-like character. As evidence of this are cited the facts that the 

principal, deposits occur along the line of an anticline, filling cavities 

produced by the0 folding and falling down of portions of the included 

strata of the gneiss. The deposits are all of very limited extent, the 

largest appearing at the surface not more than 220 feet in length, the 

widest part being about 60 feet. The aggregate length of all the limestone deposits occurring in a line some 25 miles in length is probably
366 PRE-CAMBRIAN RO'CKS OF NORTH AMERICA. [BULL. SB.

less than 1,000 feet. The principal masses are coarsely crystalline 

niagnesiaii limestones, homogeneous iti texture, and showing no traces 

of stratification. The various silicates occur attached to or near the 

inclosing walls of the cavities.

DODGE,48 in 1875, divides the rocks of eastern Massachusetts into 

two groups, the crystallines and the more clearly stratified rocks 

among them. In the crystallines are placed the syenite and greenstone. 

These rocks have a dip to the west or northwest, and they uncontbrrnably underlie strata holding Paradoxides. For the most part 

metamorphism has been so complete that the rocks have entirely lost 

their original character. While eruptive rocks have often an appearance of schistose structure, in metaiaorphic syenites and diorites, on 

the other hand the original stratification is often completely lost. 

Throughout the crystalline area there are immense masses of hornblende rock, diabase, and diorite, usually crypto-crystalline, in which 

no indication of sedimentary origin can be traced. The syenites consist of quartz, feldspar, with little or no hornblende. The porphyry 

probably belongs with the crystalline group, and pebbles of it are 

abundant in the Brighton conglomerates. Perhaps some of the slates 

are so altered in this region as to resemble real porphyry.

Among the second division are siliceous slates and breccias. The 

siliceous slates are often much contorted. At Arlington they pass 

through fine grits and coarse syenites by various stages. The crystallines occupy distinct bands, separated by more recent rocks collected 

in the area between them. These more recent rocks are shown to be 

such by their position in relation to the underlying crystallines, as well 

as by the fact that they are composed of detritus of the latter. Tii 

places they are fossiliferous, and at Braintree contain the Paradoxides 

fauna. These stratified rocks are in part slates and in part conglomerates, the former appearing to occupy the inferior position. The conglomerates are well developed in the vicinity of .Newport and dewberry. 

Cutting the slates and conglomerates are rocks which have been called 

eruptives, but so close is the resemblance in chemical and mineral composition and in appearance to the more fusible portions of the crystallines that it seems almost unreasonable to doubt that the former 

were derived from many deep lying masses of the latter.

CEOSBY,49 in 1876, describes and maps the Eozoic rocks of Massachusetts. They are divided into Norian, Huronian, and Montalban on 

lithological and chronological grounds. The lithological characters of 

the divisions are as unlike as the fauna of any two successive geological formations. The Korian is found in two areas in Massachusetts; 

that including the city of Salem and adjacent region, and that which 

includes the seaward end of large Nahant. The Ebrian rocks, composed chiefly of feldspar, hornblende, and pyroxene, are sometimes 

stratified and in other places massive. The Huronian rocks occur 

over a wide area, having an extreme length of 65 miles and an extreme
VAX HisB.i EASTERN UNITED STATES. 367

breadth of about 40 miles. The, Huroui.au comprises areas marked on 

the geological map of Hitchcock as syenite, porphyry, and hornblendeslate. The rocks here included a,re treated under hornblendic granite, 

felsite, diorite, stratified rocks, and limestones, all of which are regarded 

as metamorphosed sedimentary beds. The Montalban includes granite, 

which comprises exotic, indigenous and endogenous forms, gneiss, micaslate, argillite, and limestone. Most of the slates in the vicinity of 

Boston are regarded as of Primordial age, although fossils hav£ only 

been found at Braintreo. The argillite of Kents island and the inetainorphic slate of Newport are also regarded as Paleozoic.

BuRBANK,50 in 1876, lithologically divides the formations of the 

Nashua, valley into (1) argillite; (2) mica-slate and quartzite; (3) 

granite and granitoid gneiss. With the argillite and mica-slate are 

small beds of conglomerate, and inclosed in the gneiss are nodular 

masses of crystalline magnesian limestone. In the slates at Harvard 

aud Bolton occurs' conglomerate in which the pebbles in many cases 

are flattened, bent, and even drawn out into layers, giving an agate- 

]ike structure to the rock. The principal conglomerate beds lie between 

hills of granite on the west and north and mica-slate and gneiss on the 

south, yet not a pebble of granite or gneiss has been discovered. As 

1 to the age of the Nashua rocks no positive opinion is offered, but the 

author is inclined to regard them as belonging to a distinct system 

older than the Wachusett gneiss. The mica-slate appears to be interstratified with and overlie the gneiss, and the argillite beds appear to 

be for the most part conformable with the mica-slate.

DANA,51 in 1877, maintains that the garnetiferous mica-slate, staurolitic slate, mica-schist, gneiss, and quartzite of Bernardston are Helderberg, on the ground that in these rocks are found fossils indicating this.

WADSWORTH,53 in 1879,- describes the felsites of Marblehead neck as 

altered rhyolites, which shoAv characteristic fluidal structure. These 

felsites are not stratified, and are younger than the granite on. the neck, 

as dikes of felsite are seen cutting it. There is no passage of the conglomerate into the felsite in this locality.

CROSSY,53 in 1880, divides the Azoic formations of eastern Massachusetts into Naugus head, Huronian, and Montalban, these terms 

being used on account of a lithological and strati graphical resemblance 

which they bear to the Azoic divisions of other regions. The Naugus 

head is provisionally regarded as equivalent to Hunt's Norian (although 

it contains no labradorite), as older than the Huronian, and the Huronian older than the Montalban. The entire Naugus head formation 

seems to have been plastic, and the extraA^asation has been so extensive that the character of the rocks changes at nearly every rod to varieties regarded as composed of metamorphosed stratified rocks. The 

Naugus head series has been extensively extravasated through the superjacent Huronian formation, but is penetrated by nothing foreign, to itself, 

the Huronian granite being never found to cut the Naugus head series,
368 PRE-CAMBEIAN ROCKS OF NORTH AMERICA. [BULL.86.

from which the conclusion is formed that the IsTaugus head is older than 

the Huronian. In fact, the Huronian granite pierces every rock in the 

region save the JsTaugus head series and the newer uncrystallines, so 

that it can not be doubted that it overlies this ancient terrane. The 

latter must be regarded as the lowest, and hence the oldest member of. 

the succession.

The Huronian is principally composed of granite, petrosilex, diorite, 

hornblendic gneiss, and limestone, this being the order of age from the 

base upward. The pe.trosilex is the most characteristic rock. In the 

Huronian distinctly bedded rocks are the exception. Although many 

apparently structureless rocks are probably really stratified, it is undoubtedly true that a large part, perhaps the greater part, of the formation has been more or less fluid, and extravasation maybe set down as 

a characteristic structural feature. Besides cutting various rocks, in 

the granite at many points at the contact with the mica-slates are 

found angular fragments of the latter. The induration of the slate and 

conglomerate at points where they adjoin the granite, with the frequent 

development of amygdaloid characters, a.re facts which tell strongly in 

favor of the igneous character of the granite. The petrosilex is frequently cut by the granite, but the reverse is never the case. There is 

an apparent transition between the granite and the petrosilex or porphyry. The two are regarded as conformable, both having been metamorphosed from the same set of sediments, the more crystalline character of the granite being due to its greater depth. With the diorite is 

included all the basic rocks which have been fluid. These blend with 

and grade into the stratified hornblende-gneisses.

The Montalban series in the area covered is the most important oi 

the three systems. It comprises the ascending conformable succession, 

granite, gneiss, mica-slate, argillite, and limestone, although subordinate breaks of 110 great importance occur. The granite acts as an 

exotic to a large degree, although it is believed to belong with and 

come from the endogenous metamorphic granite at the base of the 

series. The exotic granite has sometimes cut rocks as new as the Carboniferous. Granite grades into gneiss, the gneiss into mica-slate, and 

the mica-slate into argillite, in which are found the conglomerate 

bands. In these conglomerates in many cases the pebbles have been 

flattened, bent, and even drawn out into lenticular layers, developing 

a schistose structure. One of the best localities is that at Bellingham.

The Shawmut group is a fragmental series resting unconforinably 

upon the Huronian terranes. The chief constituents of the Shawmut 

group are breccia and amygdaloids, the relations of which are somewhat uncertain. The petrosilex breccia of the Shawmut group are 

oftentimes very like the petrosilex of the Huronian. This group is perhaps equivalent to the copper-bearing rocks of lake Superior which 

they resemble lithologically. The Paleozoic formations form different 

troughs which rest unconforniably upon the older series.
VAN HISE.] EASTERN UNITED STATES. 369

DiLLER,54 in 1881, describes the felsites and their associated rocks 

north of Boston. The granite is found to contain fragments of distinctly stratified rocks, and is regarded as an eruptive rock. The felsites are found to have all the microscopical characteristics of eruptive 

rocks; to cut both the stratified rocks and the granites; to show no 

transitions into the clastic rocks, and are regarded as eruptives. The 

diorites contain distinct fragments of the granites and felsites, cut 

across the bedding of the stratified quartzites and schists, and are eruptives of later age than the granite and felsite. The framgental rocks 

are in. part older and in part younger than the felsites, as a portion of 

them is cut by the felsites while certain conglomerates contain fragments derived from the felsites.

WADSWORTH,55 in 1882, states that the Quincy granite is eruptive, 

as is shown by the fact that its junction with the slate is irregular. 

Along the contact the latter rock is greatly indurated and changed in 

color, and the granite has lost its distinctive characters, being transformed into a spherulitic quartz-porphyry.

WADSWORTH,56 in 1882, describes as a trachyte at Marblehead neck 

and having all the characteristics of this eruptive rock, a rock which 

Crosby has described as a sandstone or arenaceous slate.

WADSWORTH," in 1884, describes the relations of the argillite and 

conglomerate of the Boston basin. At the junction of the two the 

argillite is found to be irregularly eroded and the conglomerate laid 

down uuconformably over it; in places the argillite is cut off and the 

conglomerate abuts unconformably against it, and pebbles of the argillite are found in the conglomerate at the junction. There are at least 

two distinct argillites. One, underlying the conglomerate at Beacon 

street, resembles that of the Paradoxides argillite at Braintree; the 

other, of a coarser grain, oftentimes a true sandstone as far as its relations have been ascertained, is a component part of the Eoxbury conglomerate. So far as any evidence is at hand, the oldest surface rocks 

in the basin are the argillites and schists. Of these the age of only a 

small area at Braintree carrying Paradoxides is known. Through the 

schists and argillites have been protruded immense quantities of eruptive rocks in the forms of lava flows, ashes, dikes, and bosses.

PERRY,58 in 1885, states that the mica-schist at Worcester contains a 

coal seam, and bears fossils of Carboniferous age. The mica-schist is 

cut by granite.

JULIEN,59 in 1887, describes the succession of rocks in the Great Barrington, from the base upward, as consisting of Stockbridge limestone, 

schist or gneiss, quartzite, a,nd dolomite. The proof that the dolomite 

occupies a distinct bed at a higher horizon from the main sheet is clear.

EMERSON,60 in 1887, describes the succession of crystalline rocks in 

Hampshire county, in order of their age from the base up, ;is gneiss, 

feldspathic mica-schist, hornblende-schist, hydromica-schist, and calcifBull. 80 24
370 TEE-CAMBRIAN ROCKS OF NORTH AMEKICA. [BUM.. 8(5.

erous mica-schist. Granite and syenite are placed as eruptive rocks of 

the older series.

CROSBY,61 in 1888, maintains that there are no Carboniferous beds in 

the Boston basin; that it contains essentially one formation of conglomerate and one formation of slate; that these sediments include the 

Paradoxides bed at Braintree, are ^conformable, and therefore are Primordial or at least of Cambrian age; that the conglomerate underlies 

the slate. The pebbles of the conglomerates are made up of crystalline 

rocks of the regions adjacent. The contacts of the conglomerate and 

felsite are always well defined, and fragments of the latter are always 

contained abundantly in the former. The same relations hold between 

the granites and conglomerates. The conglomerates and slates have 

often a well developed cleavage, which frequently cuts across the bedding, although in places where the folding has been intense the two 

correspond. The discordance is shown by bands of the conglomerate 

cutting across the cleavage.

SiiALER,62 in "1889, describes cape Ann as consisting mainly of granite, which is cut by very numerous dikes of diabase and quite abundant ones of quartz-porphyry. Squam river is an area of diorite. The 

relative age of the granite and diorite has not been determined.

EMERSON,63 in 1890, describes the Bernardston series of rocks. The 

succession is here found to consist of fourteen members. From above 

downward the upper seven consist of alternations of mica-schist and 

hornblende-schist, after which follow quartzite, hornblende-schist and 

magnetite, limestone, hornblende-schist, quartzite-conglomerate, argillite, and calciferous mica-schist. The whole series is very crystalline, 

some parts so thoroughly so as to have been compared by Hitchcock 

with the .Bethlehem gneiss, his basement Laiirentian. In the limestones 

fossils are found of such a character as to prove that the whole series 

is Upper Devonian.

EMERSON,6'4 in 1890, describes the rocks of central Massachusetts, 

between the Berkshire limestone and the Boston basin, as consisting of 

a series of mica-schists, quartz schists, and hornblende-schists, presumably Paleozoic, and eight bands of granite and granitoid gneiss, 

in small part Arehean, in larger part Cambrian, and in largest part 

intrusive. In the western part is a small row of Archean ovals, about 

Avhich are the Cambrian conglomerates and conglomerate-gneisses, the 

latter rocks having a qnaquaversal arrangement. Here are included 

the Prineeton and Athol granites, often well foliated, which have a great 

extent north and .south. To the great intrusive masses of granite is 

applied Suess's name batholites. These have melted their way through 

a great thickness of folded strata and absorbed much of the latter in 

their own mass. At times the central masses of granite are cut by 

dikes of coarse muscovite-granite which seem to be later intrusions. 

About the batholites are broad areas in which contact metamorphism 

lias altered the rocks, changing the argillites to mica-schists, etc. Tho
VAX HISE.] EASTERN UNITED STATES. 371

contact metamorphism has a zonal character. The Barre and Orange 

bands of biotite-granite so combine the peculiarities of the Cambrian 

conglomerate-gneisses and the batholitic gneisses that no opinion is 

expressed as to their origin.

PUMPELLY,65 in 1891, describes Cambrian quartzite as resting nn. 

conformably upon granitoid gneiss at Clarksburg mountain. In the 

granitoid gneiss is found a dike which has been decayed and washed 

out before the qnartzite was deposited, leaving a fissure which caused 

the beds of quartzite to thicken and sag, and which contain at the bottom material derived from the dike. On Hoosac mountain there is 

a core of granitoid gneiss, upon which rests unconforinably at the axis 

coarse basal conglomerate with a sharp contact. In other places there 

is an apparent gradation between the metamorphosed conglomerate 

and the granitoid gneiss. This Cambrian quartzite-conglomerate is 

found to vary laterally in the legs of the fold into completely crystalline white gneiss. The Cambrian formation, containing Olenellus 

fauna, mantles around the pre-Cambrian granitoid gneiss, and the 

whole mountain is an overturned fold.

PUMPELLY,66 in 1889, gives a systematic general account of the Green 

mountains in Massachusetts. These include three principal elements, 

Hoosac mountain, the Taconic range, and the great valley between 

these. The mountain rocks are composed of crystalline schists, Avhich 

are found to be of Cambrian and Lower Silurian age, resting on proCambrian rocks. The valley has a floor of crystalline limestone or saccharoidal marble, on which are ridges of schists, both being of Lower 

Silurian age. The Tacouic range is a synclinal in the Lower Silurian 

schists, the limestone foundation appearing only at its base. At 

Hoosac mountain the succession is (1) granitoid gneiss; (2) quartziteconglomerate and white gneiss; (3) Hoosac phyllite, and (4) Rowe schist. 

On Greylock the succession is (1) Stockbridge limestone; (2) Berkshire 

phyllite; (3) Bellowspipe limestone, and (4) Greylock phyllite. At 

Hoosac mountain the quartzite-conglomerate and white gneiss appear 

to grade down into the granitoid gneiss in perfect conformity. At 

Stamford a basic dike was discovered which cuts the granitoid gneiss, 

but stops abruptly at the quartzite. Indeed, the quartz ite sags down 

at this place, its layers thickening and filling the hollow. These relations are considered definite proof of an unconformity between the 

granitoid gneiss and the quartzite. The general transition between the 

two is explained by considering the granitoid gneiss as disintegrated 

at the time of the transgression which formed the quartzite. The 

quartzite-conglomerate and white gneiss are traced into each other laterally, and are therefore but different formsof a sediment of the same age, 

and unequally metamorphosed. Across the valley the Hoosac phyllite 

was traced by gradual transitions into the limestone; and the Stockbridge limestone, Berkshire phyllite, Bellowspipe limestone and Greylock phyllite are all correlated with the Hoosac phyllite. In the quart z*
372 FEE-CAMBRIAN EOCKS OF NOETH AMEEICA. [BULL. SO.

ite is found the Olenellus fauna, hence the only pre-Cambrian rock is 

the granitoid gneiss. In structure Greylock is a complex synclinal, 

Avhile Hoosac mountain is an anticlinal overturned toward the west. 

At the ends of the Hoosac ridge the anticlinal bends nearly to an east 

and west direction. This is explained by regarding the granite-gneiss 

as a rigid mass which resisted the lateral thrust, and the abnormal 

overfoldings as the result of compensatory movements.

WoLFF,67 in 1889, gives a systematic account of the geology of Hoosac 

mountain. The rocks of the region are thoroughly crystalline, but 

little trace remains of their original elements, whether of detrital or 

of eruptive origin; but the bedding corresponding to their original, 

planes of deposit is well marked, and under proper conditions the order 

of succession can be determined. The basement rock is a coarse 

granitoid banded gneiss, which forms the base of the Hoosac mountain, 

proper. Crushing and development of new minerals makes it perhaps 

impossible to say certainly what is the origin of this rock. It could 

perfectly well be an eruptive granite modified by metamorphism, 

while on the other hand its field relations show its close association 

with and frequent transition into coarse gneisses which seem to form 

a part of the detrital series.

Overlying the granitoid gneiss is a series of rocks called the Vermont formation. At one place, where perhaps folded, it is 600 or 700 

feet thick. This formation contains numerous gradations between coarse 

gneisses similar to the basement gneiss; finer grained banded gneisses; 

gneisses with but a small amount of mica; inetamorphic gneiss-conglomerate; ordinary quartzite-conglomerate and quartzites. These 

phases pass into each other along the strike. In. the inetamorphic conglomerate it is difficult or imiwssible to separate the old quartz and 

feldspar from that formed ill situ. The rock is considered inetamorphic 

because of the shape and distribution of the pebbles in alternations of 

coarse and fine materials, because of the diverse nature of the pebbles, 

including blue quartz, white quartz, grauulite rock, and granite, and because of frequent transitions into quartzite and quartzite-con glomerate.

The next member of the series is the Hoosac schist, which conformably overlies the Vermont formation. In this schist no recognizable 

clastic element is found. The minerals appear to have formed contemporaneously. This schist is often coarsely crystalline, yet it is very 

similar to the ulbite phyllites of Germany.

The next rode found is the stratified limestone, which occurs in 

the Hoosac valley, where it is in contact with the Vermont formation and the Hoosac .and Berkshire schists.. The rock is generally an 

impure, coarsely crystalline white marble. Layers of quartzite are 

frequent, in the limestone and the change from one to the other is 

gradual. Also, there is in some sense a transition between the Stockbridge limestone and Vermont gneiss, and also a transition between the 

limestone and Hoosac schist. There also occur certain dark colored
VAN HISK.I EASTERN UNITED STATES. 373

rocks iuterstratitied with and in one case cutting the others, amphibolites. Detailed descriptions are given of the occurrences at the various 

districts.

At the Hoosac tunnel the main facts brought out are that there is a 

large central mass of coarse granitoid gneiss (Stamford gneiss) forming 

the core of Hoosac mountain; that this is flanked on both sides by the 

white gneiss-conglomerate (Vermont conglomerate), the eastern band 

having a steady dip east and overlain by the albite-schist series; the 

western band broader, with varying dips, passing by gradual transitions into the coarse gneiss, and bounded on the west by a narrow band 

of the albite schist (Hoosac schist), the contact being conformable and 

transitional. This schist is succeeded on the Avest by another band of 

fine grained white gneiss (Vermont), and this in turn by the limestone 

(Stockbridge), no contacts being observed. The structure is anticlinal.

This succession and these relations are found to correspond with the, 

distribution in the central district of Hoosac mountain. It is also found 

that the anticlinal of Hoosac, consisting of the Stamford gneiss, Vermont formation and Hoosac schist, has a pitch to the northward of from 

10° to 15°, while the western side has been overturned, which makes 

the beds in inverted order on the west side. The whole northern third 

of the region and a broad strip along the east is occupied with albitephyllite. In the district south of'Cheshire and that of Hoosac valley 

the Stockbridge limestone and Vermont quartzite are found to be conformable, and the latter lower in horizon, as shown by contacts, lithological passages and the corrugations of the two together; the quartziteeonglomerate of the Vermont formation is identical with the fine grained 

white gneisses of the Dalton-Windsor area and to those of Hoosac mountain; and the schist area of Hoosac mountain is conformable with the 

qua.rtzite and white gneiss series of Hoosac valley. The Hoosac valley 

schist and limestone appear to be conformable, although contacts arc 

wanting.

At Clarksburg mountain the granitoid gneiss (Stamford gneiss) is 

overlain by Clarksburg quartzite (Vermont formation), in which. Walcott has found, remains of trilobites, showing it to be Lower Cambrian. 

The two in a general way appear to be conformable, but in one place an 

undoubted dike runs in a straight line through the granitoid gneiss, 

but abuts against the quartzite without passing into it; and the quartzite has a curious thickening of its layers where the dike joins it, as 

Miougk there had been a hollow owing to erosion of the dike before the 

deposition of the quartzite. It seems, therefore, to show the most perfect unconformity between the granitoid gneiss and the overlying quartzite. although the structure of both rocks is parallel. Excepting the 

granitoid gneiss and the amphibolite, if the rocks are simply the Cambrian and Silurian limestones, sandstones and shales, altered by metamorphism, as they appear to be, the transition ought to be traced to 

the unaltered forms toward the Hudson. An examination of the rocks
374 PJKK-CAMBHIAN ROCKS OF NORTH AMERICA. [»uu-.«w,

of Grey lock suggests that the metaniorphism .is in general in accordance with this idea eastward, and also perhaps downward.

As a result of the work it is concluded that the gneisses of the Green 

mountains are just as capable of stratig'raphical investigation as the 

unaltered sediments of the Appalachians, only the problem, is much, 

more difficult, owing to the secondary structures produced by metamorphism.

DALE,''8 in 1889, gives a systematic treatment of the structural and 

area! geology of Greylock. The rocks are all nietamorphic and of tew 

kinds, crystalline limestone and various schists. The key to the structure is in the distinction between cleavage foliation and stratification 

foliation. The phenomena of cleavage .and stratification as studied on 

(Ireylock lead to the adoption of the following structural principles: 

1. Lamination in schist or limestone may be either stratification foliation or clea.vage foliation, or both, or sometimes, in limestone at least, 

" false bedding." To establish conformability the conformability of the 

stratification foliations must be shown. II. Stratification foliation is 

indicated by: (ft) The course of minute but visible plications; (I) the 

course of the microscopic plications; (c) the general course of the quartz 

laminae whenever they can be clearly distinguished from those which 

lie in the cleavage planes. III. Cleavage foliation may consist of: (a) 

Planes produced by or coincident with the faulted limbs of the minute 

plications; (I)) planes of fracture, resembling joints on a very minute 

scale, with or without faulting of the plications; (c) a cleavage approaching slaty cleavage, in which the axes of all the particles have 

assumed either the direction of the cleavage or one forming a very acute 

angle to it, and where stratification foliation is no longer visible. IV. 

A secondary cleavage, resembling a minute jointing, occurs in scattered 

localities. V. As ascertained by Puinpelly, the degree and direction 

of the pitch of a fold are indicated by those of the axes of the minor 

plications. VI. The strike of the stratification foliation and cleavage 

foliation often differ in the same rock, and, as suggested by Puinpelly, 

are then regarded as indicating a pitching fold. When the fold is 

horizontal the two are parallel. VII. Such a correspondence exists 

between the stratification foliations and cleavage foliations of the great 

folds and those of the minute plications that a very small specimen 

properly oriented gives, in many cases, the key to the structure over a 

large portion of the side of a fold.

There are large a.reas, sometimes half a mile square, where the only 

foliation presented by the outcrops is of secondary character and where 

no trace of stratification can be detected. As the cleavage foliation in 

some places coincides with the stratification foliation both in strike and 

dip, in others agrees in strike while differing in angle of dip, and in still 

others differs both in strike and dip, and, furthermore, as the marks 

of stratification are not infrequently subject to purely local changes, 

the whole matter is attended with much difficulty. As a rule the
VAN.HBB.J EASTERN UNITED STATES. 375

most reliable structural data on Greylock have been obtained from, 

outcrops where two different beds were in visible contact, or from a 

series of related outcrops in all of which both cleavage filiation and 

stratification foliation were equally manifest and discordant, or else 

from, large surfaces of rock at right angles to the strike where the 

general trend of the minor folds could be distinctly seen. As a result of a large number of observations the difference in angle of dip 

between, the cleavage foliation and stratification foliation was found to 

be from 10° to 120°. When the difference is over 90° the direction of 

the two dips is opposite. The absolute dip of cleavage in. a large 

number of cases is almost universally to- the ea>st. Also, there is lack 

of conformity in the strikes of the cleavage foliation and stratification 

foliation.

Early in the work attention was directed by Pumpelly to methods of 

detecting the pitch in the axes of folds. It is usually determined by 

observing the pitch of the axis of any part of the fold. The correctness of the method seems to be verified by the general, parallelism 

which exists between the minute and general structure of the rock 

masses, and also by the opposite direction of the pitch as determined 

at the extreme ends of the mountains. An application of these principles to Greylock shows that the range consists of a series of more 

or less open or compressed synclines and anticlines which, beginning 

near North Adams, increase southerly in number and altitude with the 

increasing width and altitude of the schist area, and then, from a point 

about a mile and a half south of the summit, begin to widen out, and 

to diminish in number and height until they finally pass into a few 

broad and low undulations west of Cheshire. Between that point and 

the villages of Berkshire and Lanesboro the folds become sharper and 

more compressed and the schist area rapidly narrows, terminating 

within a short distance of Pittsfield.

Mount Greylock, with its subordinate ridges, is then a synclinorium, 

consisting at the surface of eleven synclines alternating with as many 

anticlines, but in carrying the sections downward they are resolved 

into two great synclines with several lateral and minor ones. There 

are five more or less distinct lithological horizons in the Greylock mass.

Beginning above, the succession, and correlations, with the classifications of E. Emmons, James Hall, Dana and Walcott, are as follows:
Horizons, natural 

order.

V. ......

(Upper schists.)

rv. ...... ..........

(Upper limestone.)

III... .............

(Lower bchisls.)

II .................

(Lower limestone.)

I...................

(Quartzite.)

Lithological character.

M-'iscovite (sericite),chloriteand qiiartz-schist.with or without biotite, albite, magnetite, tabular crystals or lenticular 

plates of interleaved magnetite and cblorite; ottrelite, 

microscopic rutile and tourmaline. 

These schists are rarely calcareous or graphitic.

Thickness.

Feet. 

1, 500-2, 200

Limestone, more or less crystalline, generally micaceous or 600-700 

pyritiferous, passing into a calcareous mica-schist or a i 

ieldspatllic quartzite or a fine-grained gneiss with zircon ,' 

and microchne or a schist like V and 111. 

The more common minerals are: graphite, pyrite, alhite 

and microscopic rutile and tourmaline. More rare: ga- ; 

lena and zinc- blende.

Muscovite (sericite) chlorite and quartz-schist, with or 

without biotite, albite, graphite, magnetite; frequently 

with tahular crystals or lenticular plates of interleaved 

magnetite and chlorite ; garnet; (ottrelite?); microscopic 

rutile and tourmaline. 

These schists are in places calcareous, especially toward 

the underlying limestone.

Limestone, crystalline, coarse or fine ; in places a dolomite, 

sometimes quartzose or micaceous, more rarely feldspathic, very rarely fossiliferous. Galena and zincblende 

rare. 

Irregular masses of iron ore (limonite), associated sometimes with manganese ore (pyrolusite). Some quartzite.

Quartzite, fine grained, alternating with a thin-bedded, 

micaceous and feldspathic quartzite. (The latter with 

calcite, pyrite. tourmaline.) 

Associated with these quartettes, and probably at the base 

of this horizon, is a coarse grained micaceous quartzite 

(tourmaline) passing, in places, into a conglomerate, and 

containing blue quartz, feldspar (plagioclase, microcline) 

and zircon, all oi clastic origin.

Total thickness :

1, 000-2, 000

1,200-1:400

800-900

.

5, 000

7, 200

 A-ge.

Emnions, 1833.

Pre-Potsdam . 

Lower laconic 

!No. 5, ' talcose 

or magnesian 

slate. "

Pre-Potsdam . 

Lower TaconkXo. ft, included 

iri "talcose or 

in a g n c,s i a n 

slate."

Pre-Potsdam. 

Lower Taconic 

No. 3, "talcose 

or magnesian 

slate."

Pre-'Potsdam. 

Lower Taconic 

Xo. 2, ' ' Stockbridge 1 i m e - 

stone."

I* re- Potsdam. 

Lower Taconic 

Xo. 1 , ' ' granular quartz.' 1

Hall, 1839-1844.

Trenton (Hudson 

river) .

Trenton (Hudson 

river) .

Trenton (Hudson 

river) .

Lower Silurian . 

(Trenton and 

lower.)

Dana, 1882-1887.

Lower Silurian.

Lower Silurian .

Lower Silurian .

Lower Silurian .

Cambrian (Potsdam).

Walcott, 1888.

Trenton (Hudson 

river).

Trenton (Hudson 

river) .

Trenton (Hudson 

river).

Trenton (Trenton, 

Canadian, Chazy, 

calciferous) .

In part Lower 

Cambrian (Olenellus).

p; i

o

tet

O

o

O

£0 1-3

W
VAN HISE.] EASTERN UNITED STATES. 377

L1TKUATUKK OF RTIOTOS ISLAND.

JACKSON3C9 in 1840, describes the older rocks of Rhode Island as 

Primary and Metainorphic. The Primary rocks are generally said to 

be rocks'produced in the state of igneous fusion. Among these are 

placed granite, gniess and mica-slate, although it is doubtful as to the 

manner in which these two latter rocks were formed. At Woonsocket 

a conglomerate passes into a mica-slate. In general the contact between the gneiss, mica-slate and graywacke are perfectly sharp.

CozzENS,70 in 1843, finds that the section on the island of Rhode 

Island, from the base up, includes granite, serpentine, black slate, graywacke, black slate, Rhode Island coal and diluvium.

JACKSON,71 in 1859, maintains that the pebbles of the Newport conglomerates in their present condition were mechanically formed by being 

rolled upon beaches, often the distortions and indentations being accounted for in this way.

HITCHCOCK (OHAS. H.),72 in 1861, describes tbe lower rocks of the 

island of Aquidneck, in ascending order, as (1) talcoid schists, and 

conglomerates with red jasper pebbles; (2) the Purgatory conglomerate, the pebbles of which are distorted; (3) mica-schists, mica-slates, 

conglomerates, sandstones, and grits west of Purgatory; (4) second 

conglomerate, and (5) coal measures.

DALE,73 in 1883, gives detailed sections of many localities and descriptions of various places. The conglomerates are found in some 

cases to be highly metamorphic, the pebbles being unmistakably elongated and cut with scales of mica. The cleavage of the pebbles is 

regarded as partly due to their adhesion to the cement. The fractures 

with which they are cut is possibly due to wave motion or to the contraction of the conglomerate in cooling from a heated state. The 

chronological order and thickness of the series is in ascending order as 

follows:

Feet.

1. Hornblende-schist alternating with mica-schist........................ 950

2. Chloritic schists and associated argillaceous and micaceous schists..... £00-750

3. Greenish, slaty conglomerate, with argillaceous and siliceous serpentine.

(Conglomerate i.) .................................................. 500

4. Quartz and clay, aggregate............................................ 750

r>. Argillaceous schists and associated slates, etc......................... 600

(>. Qnartzite conglomerate, with grits and some argillaceous schist. (Con

glomerate 11.) ...................................................... 750

7. Carbonaceous schists and shales with argillaceous schists............. 500

8. Fine argillaceous conglomerate and grit............................... 500

Total .......................................................... 5050-5300

LITERATURE OF CONNECTICUT.

SiLLiMAN,74 in 1820, states that Primitive rocks occur in many places 

in the counties of New Haven and Litchfield. These rocks succeed 

each other with almost precisely the arrangement and succession laid
.378 PRE-CAMBRIAN HOOKS OF NORTH AMERICA, [UVU..M.

down by Werner clay-slate, including1 beds of trap; mica-slate; 

gneiss. Granite crowns the whole, although it occupies but a small 

extent compared with the gneiss and slaty rocks. As a whole the 

slates occupy the lowest and the granites and gneiss the highest situations.

MATHER,75 in 1832, describes the succession from Killingly to Haddam 

as consisting of gneiss, granite, syenite, mica-slate, hornblende-slate, 

granular quartz rock, the latter underlying thick strata of gneiss. 

Powerful veins of granite traverse the gneiss, while in other places the 

granite is found both in veins and beds.

MATHER,76 in 1834, divides the rocks of Connecticut into gneiss, 

hornblende-slate, mica-slate, granular feldspar, granular quartz, syenite, granite, limestone. The strata generally show themselves in long 

belts extending unbroken to a considerable distance. Tlie thickness 

of the gneiss at one locality is not less than 10,000 feet. At Lebanon 

the gneiss surrounding a great part of the syenite dips so as apparently 

to pass under the latter rock. The syenite is not stratified, but the 

granite is partly so. The limestone occurs in beds from 1 to 20 feet 

thick, embraced in the contorted gneiss in the northwest part of Stonington.

PEROIVAL,77 in 1842, divides the consolidated rocks of Connecticut 

into Primary, Secondary, and Trap rocks. The Primary rocks occupy 

the greater portion of the surface of the state and are divided into the 

western and eastern sections. These primary rocks are formed entirely of original materials, exhibiting no appearance of any fragment 

or remains of any anterior formation. The trap rocks are chiefly connected with the secondary rocks, although they also cut the Primary. 

These are regarded as intrusive and igneous. In describing the Primary rockvS the term parallel is preferred to stratified, as simply 

expressing the fact as to the arrangement of the minerals without implying any opinion as to the mode of formation. The western primary 

system, which extends on the west and southwest into the state of New 

York and on the north into Massachusetts, is divided into a large 

number of local formations, including the classes, mica-slate, argillite, 

granite, calciferous schist, limestone. The formations as a whole present a series of parallel ridges which have a general curvature with a 

convexity toward the east. The central portion exhibits a series of 

granitic and micaceous alternations, which appear partly as elongated 

bands and partly as isolated nuclei, generally granitic, around which 

the more micaceous formations are concentrically arranged. The eastern primary system is divided into several main groups, the rocks here 

including gneiss, micaceous and chloritic rocks. In one of the granitic 

formations the arrangement consists of a central nucleus of granitegneiss surrounded by narrow concentric ranges of various characters. 

The zone immediately adjoining the granitic nucleus is characterized 

by the almost constant presence of anthophyllite. From the coarsest
VAN- nisK.l EASTERN I'NITKD STATES. 870

granites to the ft nest and most uniform scliist the structure is characterized by a parallel arrangement of the mineral constituents. Continual alternations were observed of series of granitic, micaceous, hornblendic and various other formations. The trap rocks occurring in the 

primary and secondary formations are so near alike that they can not 

be separated, but in the primary rocks there is no conformity between 

the traps and the adjacent formations, such as prevails in the secondary. 

DANA,78 in 1872, states that the quartzite of Canaan outcrops in six 

exposures, is unconformably below the limestone, and its jointing, 

uplifting and consolidation took place before the latter was deposited.

GENERAL LITERATURE.

DANA, 79 in 1877, maintains that the conformable succession in Berkshire county, Massachusetts, and in. Vermont are the same, being (1) limestones and schists; (2) quart/ites and schists; (3) quartzites and limestones; all conformable. The Taconic range of Berkshire is probably 

Upper Trenton or Hudson river or Cincinnati. There are frequent 

abrupt transitions between the quarteite and gneiss which a.re believed 

to represent transitions from sand deposits to mud deposits in the old 

seas.

HITCHCOCK, (0. H.), 80 in 1879, describes the Atlantic system as including the highlands of the Atlantic ocean between Newfoundland and 

the Carolinas, comprising the Terranovau, confined to Newfoundland 

and Nova Scotia; the Montalban, with Green mountain branch, in 

which is the White mountains; and the Carolina or Southern, which 

culminates in the Black mountains. The rocks of the system were 

deposited in a Laurentian baSin with the Adirondacks on the west and 

the ancient gneisses of eastern Massachusetts on the east.

DANA,81 in 1880, finds that the western and easternhalves of the Green 

mountain area are one orological system, the rocks being similar, and 

all are of Lower Silurian age. With these belong part of the central 

mountain section. In view of these various considerations the evidence, although not yet beyond question, is manifestly strong for 

embracing the whole region between the Connecticut and the Hudson 

(and to an unascertained distance beyond) within the limits of the Green 

mountain synelinorium.

DANA, 82 in 1884, finds that the schistose rocks constituting the Taconic range grade from, north to south from feebly crystalline argillite 

and hydromica-schist to coarse grained mica-schist, garnetiferous and 

staurolitic. The eastern and western limestone belts blend with one 

another through the low regions, cross the Taconic line, and prove the 

two to be one formation. The limestone passes underneath the schist 

of the Taconic range and outcrops on its east and west sides on opposite 

sides of the synclinal. The limestones which constitute the lower part of 

the Taconic system contain fossils, which designate it as Lower Silurianj 

hence the schists of the "laconic are later than Silurian age and prob-
380 FRE-CAMBRIAN .ROCKS OF NORTH AMERICA. [nri.L.Sfi

ably belong to the Hudson river. The structure of tlie range is a compound synclinal. Mount Washington is a synclinal of the same kind, 

 which dies out to the south with a multiplication of small subordinate 

flexures.

HITCHCOCK (0. H.),83 in 1884, describes a number of geological 

sections across New Hampshire and Vermont, and correlates the rocks. 

The order and thickness of the crystalline formations from above downward are as follows:

	Feet. 

Calciferons mica-schist and Coos group.........'........................... 12, 000

Kearsarge group.......................................................... 1, 300

Rockingluim mica-schist.................................................. (>, 000

Merrimac group .......................................................... 4,300

Huroniau...................... 1.......................................... .12, 000

Hornblende-schist ........................................................ J, 500

Mcmtalban............ <?................................................... 10,000

Lake Winnipiseogee (Green mountain) gneiss.. ............................ 18, 600

Bethlehem gneiss ......................................................... 6, 300

Forphyritic gneiss ........................................................ 5, 000

Tota.1 thickness ..................................................... 77, 000

The various groups are classified according to stra.-ti graphical and not 

lithological reasons. Unlike rocks are never assumed to be identical. 

If a hornblende-schist and clay-slate dip toward each other they are 

assumed to be of different age and separated by a fault. If a granitic 

rock shows foliation it is classed among the gneisses. The igneous 

rocks are devoid of marks of stratification. The Montalban is used to 

cover pre-Huronian and post or upper Laurentian rocks. Huronian is 

used for convenience to designate the various schists of chloritic and 

argillitic aspect overlying the gneisses and inferior to the Cambrian so 

far as known. The Ascutney granite seems to have been erupted from 

below through one or more vents and spread over the rock adjacent, 

as is shown by the fact that in the valleys where erosion has cut into 

the base of the granite it is discovered that schists run under the igneous rock certainly for 300 feet. The mica-schists show the presence of 

heat for a distance of 500 feet or more from the granite. The slates 

have been indurated so that they ring like iron when struck with a 

hammer. The limestones are sometimes calcined and even glazed. 

Veins enter both of the rocks from several yards distant. The gneiss 

is not altered by the contact line. It would seem, therefore, as if we 

had here examples of contact phenomena, and only the later strata are 

affected, because the gneiss had been already made crystalline before 

the eruption of the granite.

HITCHCOCK, (0. H.), 81 in 1886, divides the older rocks of Vermont into 

(1) granite (Devonian); (2) Eozoic gneiss; (3) Potsdam and later formations. In (3) are included the Georgia slates, the calciferous micaschist, etc. The Eozoic gneiss occurs in five areas and is believed to 

underlie the Potsdam or Quebec group. At Wajlingford the quartzite is
VAN HISE.l EASTERN UNITED STATES. 381

Eozoic

superimposed upon a gneiss, as shown by peculiar erosion. At Sunderland, East Wallingford, Ripton, Bristol and Clarksburg, Massachusetts,' 

the fossiliferous rocks contain pebbles of a peculiar blue quartz which 

is derived from the gneiss. The gneiss is a northward continuation ot' 

the Eozoic rocks of New Jersey, the Highlands of New York and of 

southern New England. In Maine the Cambrian, Huronian and Taconic rocks are placed together and also the Montalban and Laurentian. 

The granite and trap and altered slates are not placed in the strati, 

graphical column. The gneisses are regarded as older than, either 

the Cambrian or Huronian. The pre Silurian rocks of New Hampshire are classified as follows:

'Laurentian...................Porphyritic gneiss.

f Bethlehem group. 

.... ,. j Lake Wiunipiseogee gueiss.

] Montalbau or White mountain series. 

[Franconia breccia, 

f Comvay granite. 

Albany granite.

Labrador or Pemigewasset.. ! Chocorna granite.

Ossipyte.

 

Compact feldspar. 

Exeter syenites. 

C Lisbon group. 

Huronian ..................; Lyman group.

I Auriferous conglomerate.

I

Rockingham schists. 

Calciferons mica-schist. 

. .... . _ ..._....--...-.- Coos group.

Clay slates. 

[Mount Mote conglomerate.

The Atlantic system is proposed to cover all the rocks along the Atlantic coast from Maine to Alabama, being regarded posterior in time 

to the Laurentian but anterior to the Cambrian and later formations.

WALOOTT, 85 in 1880, places the Georgia formation, which is found to 

contain the Olenellus, in the middle Cambrian, and the Braintree series 

of Massauhusett bearing the Paracloxides fauna is placed in the Lower 

Cambrian.

WALCOTT,80 in 1888, in a consideration of the Taconic, places tlie 

western core of the Green mountains as pre-Cainbrian, the bounding 

line being at a considerable, but a, varying distance east of Rutland, 

Middlebury, Burlington and St. Albans. All. of the rocks of western 

Massachusetts are regarded as Cambrian or post-Cambrian, including 

the Stockbridge limestone, the granular quartz rock, the magnesian 

slate, Sparry limestone, and Taconic slate. In northwestern Connecticut is an area of pre-Cainbrian rocks which is surrounded by quartzite 

referred to the Georgia formation.

' WALOOTT,87 in 1889, after a consideration of the Cambrian fauna 

reverses the position, of the Georgia and Braintree horizons, placing the 

latter as Middle and the, former as Lower Cambrian.

Paleozoic ..
382 PRE-CAMBRIAN ROCKS OF NORTH AMERICA.

SUMMARY OF RESULTS.

In this discussion no attempt will be made to consider in detail the 

structures worked out by the various authors in individual districts, 

but rather to indicate the general character of the results which have 

been reached.

It is plain that the knowledge of the pre-Oambrian structure of the 

New England states is in a very unsatisfactory condition. Even in 

such a district as that of eastern Massachusetts, including the Boston 

basin, there is the greatest diversity of opinion, a district which one 

would naturally expect would have been systematically studied and 

certain results reached. In western Massachusetts, where the most 

elaborate of the older surveys has been made, the rock successions 

given from time to time and the correlations with other series have varied 

greatly. These areas are.particularly mentioned because most studied. 

What is here true is still more emphatically the case with the remainder 

of the region.

While, then, systematic work in the New England states is but fairly 

begun, one great structural fact is clearly apparent, that large areas of 

rocks which have commonly been regarded as pre-Cambrian are proving to be Cambrian or post-Cambrian. This is most marked in western Massachusetts, where the recent work of Dana, Pumpelly, Dale, 

Wolff, Emerson and Walcott has establi.sl.ied tire conclusion that the 

pre-Cambrian rocks are confined to small areas. The results reached 

in this district show that it will not do to call the crystalline rocks 

pre-Cambriau and the uucrystalline ones post-Cambrian, a principle 

clearly recognized by Adams and the elder Hitchcock many years ago. 

Over large areas mica-slates, mica-schists and evenly granular gneisses 

have been demonstrated beyond all question to belong to the Cambrian 

or post-Cambrian. If in the remainder of New England the pre-Cambrian .rocks shrink in proportion, as they have done in the districts 

closely studied, they will not occupy more than a fraction of the area 

usually assigned to them.

If it be true that a very large proportion of the New England rocks 

which have been supposed to be pre-Cambrian are really Cambrian or 

post-Cainbrian, it is evident that the reference of them to tire Moutalbau, Noriau, Huronian, Laurentian, etc., is wholly unwarranted. In 

the districts already referred to where definite knowledge is available 

many of the rocks before referred to these various series are being 

divided into two classes, sedimentary and igneous, and are being distributed from the Cambrian to the Carboniferous.

As yet it can not be positively said of any district that tire preCambriau rocks can be subdivided upon a structural basis, although 

recent unpublished results by Pumpelly and his assistants in the Green 

mountains indicate that it may be possible to do this in the future.

This New England region is one of great interest as being the first 

in which it was clearly shown by structural work that fragmeutal rocks
VAN niRB.] EASTERN UNITED STATES. 383

pass over into crystalline schists. The descriptions by the elder 

Hitchcock of the way in which the schist-conglomerates at various 

points pass over into mica-schist in which no trace of the pebbles remain are remarkably like those given many years later by Keusch, the 

chief difference being that in the latter case partly destroyed fossils 

were found in the semi crystalline rocks. Hitchcock's summary of the 

evidence for the production of completely crystalling schists from fraginental rocks over extensive areas, published in 1860 in the Vermont 

reports, is demonstrative in its nature. The case could hardly be put 

more forcibly at the present time, except by the additional evidence 

derived from microscopical structures.

One of the most interesting differences of opinion has been as to the 

origin of the granite and its relation to other rocks. The elder Hitchcock believed that the granites and syenites arc produced by the 

iiqiieo-igneons fusion of the sedimentary beds, that they have usually 

not moved far, and thus represent older stratified rocks. Locally it was 

recognized that they have become fluid and have intruded the adjacent rocks, showing all the characteristics of an ordinary eruptive. 

The term nietamorphic was made to cover this once fluid material. Along 

the contacts of the granite with the slates and schists, at various 

localities were found many rounded fragments which were taken as evidence of the metamorphic origin of the whole, the matrix being regarded as completely fused and the fragments as residuary bowlders 

which had resisted the process of metamorphism. Stevenson and Marvine interpreted like facts in the Kocky mountains in the same manner. These relations are precisely the same as those described by 

Lawson between his Laurentian granite-gneiss and the clastic series 

northwest of lake Superior. The latter writer, however, declines to 

carry the term metamorphism over to the final product and regards the 

granite-gneisses along the contact zone containing fragments of the 

adjacent rocks as irruptive ones, the fragments being caught in the 

fluid material rather than being a residual uufused substance. The 

emphasis is then thrown upon the intrusive character of the granitegneiss, a position less consonant with the theory of subcrustal fusion 

than that of Hitchcock, Stevenson, Marvine, and Winch ell. An objection to the acceptance of this theory of the origin of granite and granite-gneiss is that it is one that is not easily verifiable. As soon as a 

rock becomes liquid it does not longer reveal the source of the material, 

and the conclusions that it has not moved far and has been produced 

by the fusion of the adjacent rocks is an unproved and perhaps improvable assumption.

By Orosby the granites which cut other rocks are placed as the 

older; this conclusion follows from the hypothesis that the granites are 

metamorphic. If they intrude overlying rocks they must have been 

produced from a more deeply buried series and are hence older. Most 

geologists interpret these relations to mean that the granite is a later
PEE-G'AMBEIAN EOCKS OF NOETH AMERICA. [BULL. 80.

intrusive rock. By Shaler the lamination of the minerals in the syenites and granites, and particularly the more distinct lamination of the 

exterior parts of the exposures, is regarded as unquestionable evidence 

of sedimentary origin. Jackson, among the older geologists, has steadily maintained the essentially igneous origin of the granites and syenites. Hawes was the first, however, to clearly study from the modern 

point of view the granites and granite-gneisses and to show that the 

lamination of the latter is not necessarily an evidence of original bedding, and that such a structure may appear in an igneous rock as well 

as in a sedimentary one. It is only since the recent work of Pumpelly 

and Emerson that it has been generally appreciated that there are tAvo 

classes of granites in New England. These geologists have shown that 

in western Massachusetts is a granitoid gneiss, which beyond all question antedates the Cambrian rocks and has yielded debris to them. 

While this is the case, the greater mass of the granites are far later 

in age, some of them ranking in time as late as the Carboniferous. 

Frequently the masses are so large as to metamorphose the sedimentary beds about them by contact or dynamic action, or more probably 

by both, producing the concentric schistose structure so early mentioned by Percival and so fully described by Emerson.

By the early, advocates of rnetamorpbic granite a massive form was 

regarded as evidence of the completed process and of the great age of 

the granite. In any given granite the age of which is not known, from 

the modern point of view, its perfectly fresh granular form, or an even 

lamination of mineral constituents which results from crystallization 

under ordinary circumstances in great beds or masses, bears rather 

toward its late formation; while the contorted and foliated granitoid 

gneisses, because of their structures, show that they have undergone1 

repeated powerful dynamic actions, and consequently are more likely 

to be ancient rocks.

The u diorite-schists," " amphibolites," " metain.orphj.c diorites," and 

similar schistose rocks described even by Hawes as metamorphic, 

probably belong for the most part with the other greenstones, which 

have almost universally in late years been placed with the eruptives. 

These schistose phases are more ancient than the massive forms or 

have been subjected to more intense metaiuorphisin.

While it was early recognized by most geologists that slaty cleavage 

and foliation may cut across the bedding, it was generally assumed 

that cleavage and stratification foliation correspond. As early as 184U 

Percival so clearly saw the danger of this course that he states that lie 

prefers to use the term parallel instead of stratified in describing the 

structures of the crystalline rocks as expressing the fact of the arrangement of the minerals without implying any opinion as to the mode of 

formation. Hawes, in 1878, states that the granite-gneisses in their 

affinities are like the eruptive granites, the lamination being an induced 

structure which may or may not correspond with bedding in case they
VANHISE.] EASTERN UNITED STATES. 385

are completely metamorphosed material. He, however, includes among 

the metamorphic rocks diorite, quartz-diorite, and amphibolite, since 

they have marked distinctions from the fresh basic rocks recognized as 

eruptives. From the assumption that cleavage foliation and stratification generally correspond have probably resulted more mistakes than 

from any other cause.

The cautious work of Adams, the elder Hitchcock and Percival in 

correlation is noticeable. Adams preferred to call the rocks of Vermont Azoic, referring to their present state, and specifically saying that 

many of them might prove quite late in the fossiliferous series. The 

same course is followed by the elder Hitchcock, who says that probably 

most of the Vermont rocks will prove to be later than the Laurentian 

of Logan. Percival, in Connecticut, carefully described the rocks as 

they occurred without attempting to give any succession or to correlate

them with other rocks. The building up of successions upon insufficient 

data and crude correlations is mainly the work of later men.

The work of Dana, Pumpelly, Emerson, Dale, Wolff, and Walcott in 

the past decade marks a new epoch in the study of the crystalline rocks 

of New England. The complexity of the problem has been for the first 

time appreciated. It has been seen that the old method of making a 

few sections wide apart across a district, and bringing the discrepancies into harmony by assumptions, wherever necessary, of inversions 

and faults, and making correlations of formations with those of distant 

regions because of lithological likenesses, can lead only to conclusions 

worse than valueless.

In applying the new method of work, as exemplified in western 

Massachusetts, it has not been assumed that a rock stratum is the 

equivalent of another stratum in a different locality. In order to establish equivalence it is necessary that the two be actually traced together, or else that unquestionable fossil evidence be found. Instead 

of assuming that stratification and cleavage foliation correspond, the 

assumption has been rather that they usually do not correspond and 

that nothing can be taken as bedding which can not be demonstrated 

to be this, as, for instance, the contact planes of two formations, such 

as quartzite and limestone or one of these with schist. Instead of building up a structure from a few sections wide apart, all sources of information have been sought; every outcrop was visited; the information 

furnished by artificial excavations was. utilized; full suites of specimens 

were collected, and all the light which can be furnished by the modern 

petrographical methods has been brought to bear upon the problems. 

Finally, a more careful search for fossils has revealed their presence in 

rocks so crystalline that former search has resulted in failure. In this 

study Pumpelly, besides using these and other well known principles, 

has formulated new ones. These are:

(1) The degree and direction of the pitch of a fold are indicated by those of the

axes of the minor plications on its sides. (2) When the strike of the stratification

foliation and cleavage foliation dift'er in the same rock, this is regarded as i

Bull, 86 35
386 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

eating a pitching fold. (3) Such a correspondence exists between the stratification foliations and cleavage foliations of the great folds and those of the minute 

plications that a very small specimen properly oriented gives, in many cases, the 

key to the structure over a large portion of the side of a fold.

This author has further ascertained that apparent conformity, which 

 sometimes exists between strata really unconformable, may be due to 

the disintegration of the earlier series.

Notwithstanding that advantage has thus been taken of all sources 

of information, the problems of the structure of western Massachusetts 

have been found so difficult that it has taken years of labor of a number of men to build up correctly the strati graphical succession. The 

labor involved in this work and the relatively small size of the area 

covered show that before any accurate map of the whole of New 

England can be presented many years must elapse, although it may be 

reasonably hoped that, as experience accumulates, the application of 

the new method will proceed more rapidly than in the decade of its 

inauguration.

That the structural mapping of the crystalline rocks in New England is less extensive than in some other parts of America has not been 

due to a lack of ability or industry upon the part of the workers in 

this region as compared with those of others, but rather to the greater 

difficulty of the problem. This region is one in which repeated dynamic 

movements, accompanied by great outbursts of igneous material, have 

occurred until late in Paleozoic time.

SECTION II. THE MIDDLE ATLANTIC STATES. 

LITERATURE OF NEW YORK.

PIERCE,88 in 1818, describes the nucleus of Staten island as consisting of steatite, which stamps the formation, as Primitive.

AKERLY,89 in 1820, describes a section running from Long Branch, in 

New Jersey, northward to New Marlboro, Ulster county, New York. 

The rocks included are divided into principal rocks, metalliferous rocks, 

basaltic rocks, and alluvial formations, which correspond to the German terms Primitive, Transition, Floetz, and Alluvial. Staten island 

has a rocky base composed of the magnesian order of rocks, consisting 

of serpentine, steatites or soapstones. Hoboken is of the same natnro 

as Staten island. The Highlands of New York consist of granitic 

rocks belonging to the primitive class. Gneiss and micaceous schist 

are the most prominent; but granite, properly speaking, also enters into 

the composition. The commencement or termination of any of these 

rocks has not been found, and as they graduate into one another they 

are considered the same formation. At Hell Gate the rocks are gneiss 

and micaceous schist. The northern part of New York island is of the 

primitive formation and includes granite, gneiss and limestone. Crystalline limestone is also found at other points. All these rocks are 

placed in the primitive formation and they contain no organic remains.
VAN HISE.] EASTERN UNITED STATES. 387

JESSUP,90 in 1821., describes in Essex county, in the vicinity of lakes 

George and Champlain, rocks of the primitive class, including trap, 

syenite and carbonate of lime.

BATON,91 in 1822, describes as occurring in the Highlands of the 

Hudson, without reference to order of time, gneiss, hornblende rocks 

and argillite. The gneiss appears to be the center or oldest formation.

BATON,92 in 1824, describes the rocks adjoining the Erie canal. 

Among the primitive rocks are placed granite, gneiss, hornblende rock, 

mica-slate, talcose rock, granular quartz, granular limerock, sparry 

lime rock and primitive argillite, which are described as occurring at 

numerous localities. There are two primitive districts, that in southeastern New York and that west of lake Champlain, called Macomb 

mountains.

EMMONS (E,),93 in 1837, describes granite and gneiss as having a widespread occurrence in the northeastern part of the state. The granitic 

nucleus of Essex county is traversed by dikes of greenstone of igneous 

origin, and the granite is considered to have the same genesis. Gneiss, 

hornblende and granular limestone are classed together as primitive 

rocks and regarded as absolutely of the same age. Above the primitive rocks is a transition sandstone, superimposed upon which is a 

transition limestone.

CoNRAD,94 in 1837, describes at the base of the Mohawk valley ridges 

of gneiss which are regarded as a prolongation of the northern primary 

chain. Upon the gneiss is found calcareous sandstone.

MATHER,95 in 1838, mentions gneiss on Long island; granite and serpentine on Staten island; and granite, gneiss and granular quartz in 

the southeast part of Dutchess county. In the serpentine was observed 

a trap rock.

EMMONS (E.),96 in 1838, states that in St. Lawrence and Essex counties 

are found Primitive rocks. The stratification of the gneiss is often obscure and its texture confusedly crystalline. Subordinate to it and 

mingled with it is granite, which occurs in beds and protruded masses 

in the forms of veins and in overlying masses analogous to lava currents and greenstones. In St. Lawrence county is a widespread granite composed of labradorite, feldspar and hypersthene, which is traversed by dikes of greenstone, amphibolite, syenite, and porphyry. Associated with the gneiss and limestone are numerous beds of magnetite 

and hematite. The transition rocks of Essex county, such as limestones and shales, are cut by dikes and veins. The primitive limestone is always coarse, crystalline and friable. It occurs in most 

intricate and curious relations to the granite and hypersthene rock, 

many of its areas being in vein-like form. This fact, combined with 

the presence of foliated plumbago and the induration of sandstone 

when in contact with the limestone, leads to the conclusion that it is 

of igneous origin.

VANUXEM,97 in 1838, finds Primitive rocks in Montgomery, Herkimer and Oneida counties.
388 PRE-CAMBRIAN EOCKS OP NORTH AMERICA. [BOLL. 86.

MATHER,98 in 1839, describes the rocks of New York, Westchester 

aiid Putnam counties as comprising granite, gneiss, mica-slate, quartz 

rock, talcose slate, limestone, syenite, serpentine, steatite, augite rock, 

greenstone, the latter traversing the other rocks like veins or being 

interstratified with them. The gneiss and granitoid rocks are distinctly 

stratified, as is also the limestone.

HORTON," in 1839, describes the Primitive rocks of Orange county 

as less regular in stratification and dip along the banks of the Hudson and at their western margin than in their center. The strike of 

the primitive gneiss is about northeast and southwest, with a dip to 

the southeast from 45° to nearly vertical. Interstratified among the 

primitive rocks are hornblende rock and white limestone. Argillite is 

placed with the transition formations.

GALE, 100 in 1839, finds that the rocks of New York county are chiefly a 

gneiss, associated with which as subordinate rocks are serpentine, hornblende, primary limestone and anthophyllite rock. On the western side 

of the island the gneiss so abounds, with the veins of granite parallel with 

the strata, that in many places they constitute the chief material. At 

Kings bridge the limestone at its junction with the gneiss retains the 

structure of that rock with the mineral matter of limestone, but the 

pure limestone is in beds without stratification.

EMMONS (E.), 101 in 1839, describes Primitive rocks in Hamilton, Clinton and Warren counties. The primitive rocks are gneiss, hornblende, 

limestone and serpentine. The limestone and serpentine occur in irregular veins or beds, which are sometimes analogous to greenstone dikes 

so prevalent in the hypersthene rocks.

EMMONS (E.),102 in 1840, states that the magnetic iron ore occurs associated with granite, gneiss and hypersthene rock in veins which are

regarded as of igneous origin, The specular oxide occurs in two horizons, the first associated with the primary limestone, the second with 

gneiss or some other primary rock beneath it.

VANUXEM,103 in 1840, states that the primary rocks which are defined 

as earlier than any which bear organic bodies in Lewis county consist 

mostly of granite and gneiss, but are associated with amphibolite or 

hornblende, forming syenite and hornblende rock. The Potsdam sandstone rests unconformably upon the primary rocks. There is a great 

contrast between the two classes, the latter presenting a disturbed 

appearance, exhibiting high grades of inclination, while those of the 

transition are like the deposits of tranquil waters.

MATHER, 104 in 1841, states that the primitive rocks occupy two-fifths 

of Saratoga and. one-fifth of Washington county, being mostly gneiss 

and granite, although coarsely crystalline white limestone containing 

plumbago, augite and hornblende is a common rock.

EMMONS (E), 105 in 1841, mentions primary limestone at lake Janet, 

gneiss at Long lake, and on Racket river hypersthene rock.

EMMONS (E.),106 in 1842; gives a report on the entire Adirondack
VANBISE.] EASTERN UNITED STATES. 389

region. The older rocks are classified under primary and transition. 

There are few transitions from the primary into the sedimentary rocks. 

There are, however, many transitions among the primary masses themselves, and often intermediate series are found which are with difficulty 

placed under appropriate names. The primary rocks are divided into 

unstratified, stratified and subordinate. Among the unstratified rocks 

are included granite, hypersthene rock, primitive limestone, serpentine 

and rensselaerite. The stratified rocks include gneiss, hornblende, 

syenite, talc or steatite; the subordinate rocks include porphyry, trap, 

magnetic and specular oxides of iron.

The granites occupy a comparatively small extent in the region, 

being in limited patches of irregular appearance. One of the largest 

beds of granite is about G miles long. In one place granite and limeStone are somewhat intermingled, The hypersthene rock occupies a

triangular area to which it is almost wholly confined, but it constitutes 

almost the entire county of Essex, with the exception of a belt a few 

miles in width along the shore of the lake. Under primitive limestone 

is included a coarse, crystalline mass, readily recognized as a mineralogical species, but as a rock not holding a definite place in the primary series. This rock is believed to be unstratified and of igneous 

origin, as is shown by its occurrence in dike-like forms and its association with eruptive rocks, the imbedded minerals being of such a 

character as would be produced by metamorphism. Also limestone 

produces a metamorphosing effect upon the minerals imbedded in it, 

is always without stratification, often underlies granite, and is so intimately associated with it as to make it probable that the two have a 

common origin. Serpentine intimately associated with the limestone 

has 'an origin common with it.

The stratified rocks have a much wider occurrence than the massive 

ones. Of these gneiss is by far the most important. Syenite is applied to a stratified rock composed of feldspar and hornblende. It 

often oecurs injected ia the form of dikes and associated with beds of 

iron ore and is in part an igneous rock. Trap includes dark-colored 

igneous rocks, Avhich cut the various other primitive formations. These 

are compared with mineral veins, and because the former is eruptive 

the latter is concluded to have a probably similar origin. Porphyry is 

also found in igneous forms. Magnetic and specular oxides of iron, occur as masses and as veins. They are sometimes apparently interstratified with rocks with which they are associated, but often also 

break across the strata. In their mode of occurrence they resemble 

trap, greenstone, and porphyry, and are therefore regarded as of 

igneous origin. Between the primary and transition systems is the 

Taconic system.

VANUXEM,]07 in 1842, describes the primary system as occurring in 

the northern parts of Montgomery and Herkinier counties, the northeast corner of Oneida, and the whole of Lewis county east of Black
390 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

river. This system consists wholly of granite and gneiss, with which 

is associated a small quantity of limestone and. iron ore. Primary 

rocks occur isolated in the New York system ; the first at the Noses on 

the Mohawk; the second at the little falls of the Mohawk ; the third 

at Middleville. With the Taconic system are placed a lamellar white 

crystalline limestone, with specular iron ore and compact red iron ore 

and plumbaceous rocks in Lewis county.

MATHER, 108 in 1843, gives a systematic account of the geology of the 

first district, comprising the southern part of the state. The Potsdam 

sandstone is at the base of the unmodified series. In places it is metamorphic and has more or less the aspect of gneiss ; at other times it is 

in an intermediate state, showing rounded gravel and sand. The dips 

are usually eastward at from 5° to 20°, but in the Hudson valley 

it is upturned with other rocks at a high angle toward the east. 

The Taconic system consists of slates, limestones, and granular quartz 

rocks, which form a belt of mountainous country from Vermont to 

Peekskill on the Hudson and a narrow belt across the Highlands to 

the mouth of Peekskill creek. They are again found on the right bank 

of the Hudson, between Stony point and Caldwells landing, and range 

south-southwest until they disappear beneath the red sandstone formation. The strike and dip of the rocks of this system are the same as 

those of the Ohamplain division and apparently underlie them. The 

dip is in a general easterly course, varying from 15° to 90°. As to the 

superposition of the formations the granular quartz either rests upon 

or pitches under the gneiss or granitic rocks. The limestones lie next 

in order from the gneiss or granite, either in super or sub position, and 

the slates next follow. This may be found difficult of verification, as 

the rocks are almost universally much deranged from their original

position. Many local details are described, and it is concluded that

the Taconic system represents the Champlaiu division metamorphosed. 

In favor of this position are the facts that the succession is the same; 

that both of these systems are superimposed upon the primary without 

any intervening strata; the unmodified beds are traced into those that 

are metamorphic; and the places where the rocks are most metamorphic are those where there are intrusives and have been upheavals.

Under the head metamorphic rocks are described such rocks as are 

not included in the foregoing, and which, while there is no demonstrative evidence of it, are regarded as originally sedimentary rocks, which 

have since been altered in their character so as to change them into 

such rocks as have usually been called primary. The metamorphic 

rocks are divided into two divisions, those east of the Highlands of 

the Hudson, and those of the Highlands of Saratoga and Washington 

counties. In the first district the limestones are granular, dolomitized 

and stratified. The slates are talco-argillaceous, talcose, chloritic or 

micaceous, the last predominating; and the sandstones are changed 

into granular quartz rock, eurite, and gneiss. In the second district
VANHISK] EASTERN UNITED STATES. 391

the limestones are changed to white or red, coarse grained, crystalline 

limestone, containing various crystallized minerals, with scales of 

plumbago, and rarely show any traces of stratification. The slate is 

changed to mica-slate, micaceous gneiss or hornblende-slate, and the 

quartz-rock is changed so as to be scarcely recognized as such. In the 

first class, also, the intrusive rocks bear but a small proportion to the 

altered rocks and are mostly quartz and granite, but in the second 

class the undoubted plutonic rocks abound and consist of granite, 

syenite, greenstone, augite, serpentine, diallage, and intrusive metalliferous veins.

The metamorphic rocks east of the Hudson and Highlands are in a 

continuous range from Bennington in Vermont to the west part of 

Massachusetts and Connecticut and the eastern part of New York. 

Between the Taconic rocks and the metamorphic rocks to the east no 

well marked line of distinction can be drawn, as they blend into each 

other by insensible shades of difference. In considering the metamorphic rocks as a whole the descriptions necessarily include certain of the 

Taconic rocks. The strata of metamorphic rocks are very much broken, 

so that no stratum has been traced continuously more than a few miles. 

The only beds which can be traced with any degree of success are the 

limestones, which are described in detail. The limestones of Westchester county have the same dip and line of bearing as the contiguous 

gneiss, and like that, are distinctly stratified. They form several nearly 

parallel ranges at intervals of 2,3, or 4 miles. They all dip east-southeast, with local exceptions, at a high angle, varying from 45° to 90°. 

The metamorphic slates of Dutchess, Putnam, Westchester, and New 

York counties have been traced in different localities through different 

modifications and texture from the gray and semicrystallme limestones 

associated with talcose slate and the sandstone of the Taconic system, 

to the perfect dolomites and white and gray crystalline marbles associated with mica-slate and granular quartz-rock, north of the Highlands ; and to still more crystalline limestones associated with micaslate, micaceous gneiss, hornblende-slate, hornblendic gneiss, hornblende-rock, syenite and granite, south of the Highlands. In these 

latter limestones are frequently found some mineral substances, such 

as serpentine, brown tourmaline, copper and iron pyrites, magnetic 

sulphuret of iron, mica and magnesian minerals, particularly where 

near to undoubted plutonic rocks. It is believed that all the crystalline limestones of Vermont, Massachusetts and Connecticut and the 

eastern part of New York, are metamorphic rocks; ttiat they were originally the Mohawk limestone and Calciferous limestone, and that the 

associated rocks were originally the Potsdam sandstone and the slate 

rocks of the Hudson valley; that they were, in fact, the rocks of the 

Ohamplain division, but much more altered and modified by metamorphic agency than the Taconic rocks.

In the study of the metamorphic rocks of the Highlands and Sara-
392 PRE-CAMBRIAN ROCKS OF NOETH AMERICA. [BUM..M.

toga county, as in the other district, most attention is given to the 

limestones. At Warwick the white limestone is rarely stratified or 

shows any distinct traces of stratification, but in some places it exhibits a regular gradation into the gray and blue limestone, which is fossiliferous in some places and oolitic in others, and stratified in nearly 

horizontal strata. The limestones of the Highlands of Orange, Eockland,and Putnam counties are in long narrow belts associated with the 

granite, syenite, hornblende and augite rocks and some anomalous aggregates. The limestones of Washington county are coarse, white and 

crystalline. They contain various imbedded crystalline and amorphous 

minerals, the most common of which are plumbago, augite, and hornblende. Hornblende, coccolite, an'd plumbago are the most constant 

associates. Scapolite is not uncommon. In some places the limestone 

is so much intermixed with other materials found in the gneissoid and 

granitic rocks, that without close examination it would not be suspected as a limestone. Quartz is frequently found in it, transparent or 

translucent, with irregular, rounded forms, as if it had been partially 

melted. Many localities that I have visited show that it has been softened, if not melted. The similarity of the crystalline limestones of the 

northern counties to the crystalline phases of those at Warwick which 

grade unmistakably into fossiliferous forms leads to the conclusion that 

they are all really the same rock. The limonitic and hematitic ores are 

confined to the valleys of the Taconic and metamorphic rocks and are 

usually associated with talcy slate on one side and limestone on the 

other.

Under Primary rocks are included those usually called by that name 

and those not yet described as Taconic or metamorphic, though some 

of them are probably of the same age as the metamorphic rocks. This 

is particularly the case with the plutonic rocks, as granites, syenites, 

hornblende rocks, some of the trappean rocks, and the metalliferous 

beds and veins which have intruded themselves among and altered 

the adjacent rocks. The hornblendic gneiss, micaceous gneiss, and 

mica-slate may perhaps be referred to the same period. The primary 

rocks in the different districts are very similar. They include granite, 

syenite, gneiss, mica-slate, augite-rock, greenstone, hornblende rocks,' 

quartz rock, talcose slate, limestone, serpentine, and steatite, although 

the last five have been already included among the metamorphic rocks. 

In Eockland and Orange counties the strata dip to the southeast at 

angles from 50° to 90°, but there are localities where the strike and dip 

are transverse to the general directions. Granite veins are very numerous in the granitic gneiss; the greenstones include basaltic greenstone or trap, granular greenstone, and primitive greenstone. Associated with the primary rocks is magnetic oxide of iron, confined to the 

southern counties of the Highlands and forming masses in gneiss and 

hornblendic gneiss rocks which might be called beds, but which are 

thought to be veins. Their course is parallel to the layers of rock, but
EASTERN UNITED STATES. 598

in several instances after continuing with this parallelism for a certain 

distance the ore crosses a stratum of rocks and then resumes its parallelism, and then obliquely crosses another, and so on. Also in other 

places where there are great beds of ore, a few small strips of ore penetrate the surrounding rocks as if they have been cracked asunder and 

these seams forced up from the main mass below.

The rocks that are most metamorphosed are usually near granite, 

syenite, trap, quartzose and metalliferous protrusions, dikes and veins. 

It is believed that trappean injections took place as late as the time of 

the red sandstone of New Jersey. The granitic, syenitic and augitic 

rocks appear to belong to the epoch immediately preceding the slates 

and grits of the Champ! ain division, since they have altered the preexisting rocks where they come in contact up to that time, but no traces 

of such changes are found in the more recent rocks, Another intrusion

of granite is believed to have preceded the red sandstone of Eockland 

and New Jersey, being probably more recent than the rocks of the 

Catskill division.

COZZENS, Jr.,109 in 1843, divides the rocks of Long island into granite, syenite, serpentine, mica-gneiss, hornblende slate, quartz rock, 

primitive limestone and diluvium. The distribution of all is given. 

At the Palisades, on the west side of the Hudson river, the section 

from the base up is granite, serpentine (different from that at Long 

island), sandstone, greenstone-slate and trap. The section of Staten 

island from the base upward is granite, serpentine, sandstone, trap or 

greenstone, beds of iron ore and diluvium. At Donderberg the section 

is granite, gneiss, talcose slate, limestone (called transition limestone) 

and brick clay.

EMMONS (E.),110 in 1846, gives a systematic treatment of the character and relations of the Taconic system. The Taconic system is 

held to be below the New York system, because the base of the latter 

is perfectly schistose, like that of the former, and because the material of the New York system is derived from the Taconic. Again, 

contacts between the Taconic system and the calciferous sandstone 

and Hudson river shales show that the former are unconformably 

below the rocks of the New York system. As evidence that the 

Taconic system is newer than the primary rocks is the occurrence of 

porphyritic quartz of the" Taconic upon gneiss. It is, then, not to be 

doubted that there is a system of rocks lying between the Hoosac 

mountain range and the Hudson river of an age posterior to the gneiss 

and mica-slate and anterior to the New York system. It consists 

throughout of beds of sedimentary matter in a state of fine division 

conformable to each other and arranged in uninterrupted succession, 

although their lithological characters are very diverse. The Taconic 

system comprises the Taconic slate-bearing fossils, the Sparry limestone, the Stockbridge limestone and the brown sandstone or granular quartz. The primary limestone carries graphite, and on this account
394 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

can always be distinguished from Stockbridge limestone; also othei 

minerals, such as spinel, sapphire, idocrase, hornblende, pyroxene, 

chondrodite, and mica, are found plentifully in the primary, but do not 

occur in the Stockbridge. The rocks of the Taconic system are inverted, greatly disturbed, and their relations with the underlying and 

overlying rocks are obscure, so that the true structure can only be 

ascertained by most careful examination.

CREDNER, 111 in 1865, states that the island of New York and the east 

part of Long island consist of gneiss, which, toward the north, contains hornblende-gneiss, hornblende-schist, syenite, and hypersthenite, 

and in the last two are magnetite. The northern hilly part of Staten 

island consists of dioritic rocks, of serpentine, with layers of soapstone.

MACFARLANE,112 in 1865, describes the rocks in the neighborhood of 

Kossie as belonging almost exclusively to the Laurentian formation, 

which is here and there unconformably overlain by patches of Potsdam sandstone. The rocks here found comprise micaceous and hornblendic gneiss, mica-schist, gneiss-granite, granite, tourmaline rock, 

coarsely granular saccharoidal crystalline limestone, and diorite. The 

strata are in an almost vertical position.

STEVENS, 113 in 1867, describes New York island as consisting in the 

main of gneiss, in which lie veins and beds of granite, anthophyllite, 

and hornblende. The granite occurs in veins generally coincident with 

the gneiss, but also in massive beds which lie across the strata. At 

times it is distinctly separated and in others insensibly blends into the 

gneiss. The hornblende and anthophyllite occur like the granite. 

Limestone occurs at several points and is interlaminated and folded 

with the gneiss. This New York group of rocks is like and regarded

as equivalent to Emmons's Taconic, For it is proposed the name Manhattan group.

DANA,78 in 1872, describes the mica-schist of Poughquag as underlying conformably the Stockbridge limestone. The mica-schist is underlain conformably by the gneiss of the Taconic series. Besides the 

limestones and Taconic schists and gneiss, there is near Poughquag, 

in still more intimate connection with the quartzite rocks of Azoic age, 

a continuation of the highlands of New Jersey, which are probably 

Laurentian. But as this point is not definitely settled, and since the 

term Azoic has been ruled out by facts proving that the era was not 

throughout destitute of life, it is proposed to use for the Azoic era and its 

rocks the general term Arcliccan (or Archean). These Archean rocks, 

coarsely crystalline gneisses, are exposed in a deep cut on the Hartford 

and Fishkill railroad. The quartzite formation of this region shows no 

conform ability to the Archean gneiss, and none to the gnejss, micaschist, or limestone of the Taconic series. The nearly horizontal beds 

of quartzite lie on the nearly vertical Archean, and both occur within 

a few hundred yards of the steeply inclined Taconic beds.
VANHISB.] EASTERN UNITED STATES. 395

LEEDS,114 in 1878, describes the rocks of the Adirondacks. They are 

found to be stratified rocks which belong in the Norian system, are 

composed of hypersthene and diallage, and labradorite with menaccanite.

DANA,115 in 1880 and 1881, considers the geological relations of the 

limestone belts of Westchester county. The rocks here found are 

divided into metamorphic rocks, not calcareous; calcareous rocks or 

limestones; serpentines and other hydrous minerals; augitic and 

hornblendic rocks not above included. Of metamorphic rocks the 

prevalent kinds are micaceous gneiss, mica-schist, ordinary gneiss, and 

granitoid gneiss. The calcareous rocks are white and coarsely crystalline, although locally they a.re feebly crystalline. The hornblendic and 

augitic rocks constituting the Cortlandt series include soda granite,

norite, augite-norite, diorite, hornblendite, pyroxenite, and chrysolitic

kinds. These rocks are held to be conformable with a part of the adjoining schists and limestone, which are of metamorphic origin, although 

they may have been in a former state of fusion or plasticity. The limestones and adjoining schists are found to be one in series and system 

of disturbance, are considered a part of the Green mountain system, 

younger than the Highland Archean, and probably Lower Silurian. 

At Annsville there is evidence of unconformity between the Archean 

and this series. The limestone here lies unconformably against the 

hornblendic contorted Archean gneiss. A similar unconformity exists 

half a mile northeast, although the upturning of the limestone and its 

associated schist has usually placed them in near conformity to the 

strike of the Archean rocks.

DANA,116 in 1882, ascertained that a large part of the rocks referred 

to the Taconic range are shown by their fossiliferous contents to be 

Silurian and the equivalent of the Hudson river group, although it is 

not asserted that all of the hydromica-schists do belong here. A part 

are Primordial.

NEWBERRY, 117 in 1882, states that the mottled serpentine of New 

York island is like the Moriah marble of the Adirondack region, which 

affords strong indication of a Laurentian age of the New York and 

Staten Island rocks.

HUNT, 118 in 1883, describes near port Henry coarsely crystalline limestones in the highly inclined Laurentian gneisses, in which are inclosed 

irregular masses and layers of the adjacent gneiss. Although regarded by Emmons and Mather as eruptive and by another eminent 

geologist as evidence that the crystalline limestone unconformably 

overlies the gneiss, it is believed to be a great calcareous vein stone. 

The Norian, massive, bedded, labradoritic rocks are well displayed between Westport and port Kent.

DANA,119 in 1884, finds that the hornblendic and augitic rocks of the 

Cortlandt series have such relations to the schists as to show that they 

are of igneous origin, the eruptions taking place subsequent to the era 

of the limestone, mica-schist, and soda-granite.
396 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BUM,.80.

HALL (OHAS. E.),120 in 1885, states that between the limestones and 

the magnetic ore series or lower members of the Laurentian there 

is an undoubted unconformity; but the relations of the Labrador series 

to the limestone are not clear. In ascending order are the Lower Laurentian or Magnetic Iron Ore series; the Laurentian Sulphur Ore series ; the limestones and the Labrador series, or Upper Laurentian with 

its Titanic Iron Ores. The relations of the sulphur ores and limestone 

series are still undetermined. Between fort Ann and South bay, along 

the east side of the valley, the Silurian limestones lie against and apparently dip under the crystalline rocks of the Laurentian. The Potsdam sandstone, resting on the crystalline rocks of the valley, dips to 

the eastward under the Silurian limestones.

BRITTON,121 in 1886, states that a schistose series of crystalline rocks 

occurs in the Adirondacks. It consists of schistose gneiss, mica-schist, 

and hornblende-schist, and occurs north of Harrietstown and near the 

northern end of the Lower Saranac lake. Sprite occurs at Miller's 

hotel, about a mile distant.

JuLiEN,122 in 1886, states that the borders of the Adirondack region 

consist very largely of thinly bedded gneisses, especially to the eastward.

SMOCK, 123 in 1886, describes the crystalline rocks of Dutchess, Putnam, and Westchester counties. This district is divided into four belts, 

Stissing mountain, East or Dover mountain, Highlands of the Hudson, 

and Westchester county. The prevailing rocks of Stissing mountain are 

gneisses, granites, granulite, and syenite, which resemble closely those 

of the Highlands of the Hudson. The rocks of the East mountain comprise gneiss, granite, granulite, quartz-syenite, syenite-gneiss, and micaschist chiefly. Between the quartzite and the gneiss, when they are

seen close to one another, is a wantof conformability. The more common

of the rocks of the Highlands of the Hudson are gneiss, syenite-gneiss, 

granite, quartz-syenite, granulite, and hornblende-schist. The Poughquag-Fishkill quartzite is found to rest unconformably upon the Highland gneisses, the discordance being best seen on the New York and 

New England Bailroad, 1 mile west of West Pawling railroad station. 

Here the quartzite has a dip of 15° or 20°, while the gneiss, but 300 feet 

distant, has an almost vertical inclination. Belonging with the Archean gneisses are limestones, among which is that at Sprout brook. 

On the eastern side of the Highlands the Archean. border has the micaceous, schistose rocks and the quartzites resting upon it. These 

relations are particularly well shown at Towner's station. Near here 

the limestones and schists in a syncline rest unconformably upon the 

granulitic gneiss. Provisionally the rocks of the Highlands are referred to the Archean. They may be all Laurentian also, but the Huronian has not been identified. In Westchester county is a great variety 

of crystalline rocks. To these is applied the name Manhattan gneiss, 

proposed by Hall. These rocks are less massive than those of the
VANHISB.] EASTEKN UNITED STATES. 397

Highlands, include micaceous gneiss and schist, as well as crystalline 

limestones, and to the ordinary observer are more like the common 

fragmental rocks than the massive gray granitoid gneisses.

HALL (JAMES),124 in 1886, in describing the building stones, includes 

in the Laurentian rocks the granitic, syenitic, and gneissoid rocks, as 

well as the crystalline marbles which are everywhere interstratified with 

the gneiss rocks, but usually form a small proportion of the entire mass.

WILLIAMS,125 in 1886,1887, and 1888, describes theperidotites, norites, 

gabbros, and diorites of the Cortlandt series and their relations to the 

mica-schists and limestones. They are regarded as eruptive rocks because they have the structure and mineralogical composition of eruptive 

types; because their schistose phases have nothing which suggests an 

original sedimentary structure 5 because they occur in well denned dikes 

in other massive rocks, in mica-schists, and limestones ; because fragments of crystalline schist and limestone are found inclosed within the 

massive rocks; and because contact phenomena are found in the crystalline schists and limestones adjoining them.

BuiTTON,126 in 1887,'describes the serpentine of Staten island as a 

stratified rock probably derived by the extensive alterations of limestones. This serpentine appears to overlie the crystalline limestones. 

These metamorphic rocks with the gneisses are regarded as Archean.

KEMP,127 in 1887, describes Manhattan island as consisting of a long 

ridge of gneiss, with Triassic trap and sandstone on the west and connected with the gneiss of the mainland on the north and south.

MEKRILL,128 in 1890, agrees with Britton that the basal member of 

the pre-Cambrian of southeastern New York and New Jersey is a granitoid hornblende-gneiss, which is followed by a second member, the ironbearing group, and this in turn by the schistose group. The thickness of the pre-Oambrian rocks in the Hudson river valley is between 

2,300 and 2,800 feet. They are unconformably below the Cambrian 

quartzite and nothing more definite can be predicted as to their age. 

These rocks display a number of anticlines, two of which are those at 

Fishkill and the Storm King. In the synclinal trough between are the 

rocks of the iron-bearing group. The metamorphic strata of New York 

and Westchester counties, called the Manhattan group, are divided into 

several divisions from the base upward, as follows: (1) Yonkers gneiss 

which is an arkose-gneiss; (2) Fordham gneiss, a quartzite-gneiss; (3) 

Inwood limestone; and (4) Manhattan mica-schists. The age of the 

Manhattan group has not been determined, but it is thought to be preCambrian. This group and the Lower Cambrian sandstone are both 

found to lie on the second or iron-bearing member of the pre-Cambrian 

formation, and no unconformity has been found between the Manhattan group and the underlying pre-Cambrian beds. Of equal significance is the lack of unconformability between the Lower Silurian strata 

of Peekskill hollow, Tompkins cove, and Verplanks point with the partially metamorphic beds of the Manhattan group.
398 PRE-CAMBRIAN ROCKS OF NORTH AMERICA.. [BULL.86.

PUMPELLY, WALCOTT, and VAN HiSE,129 in 1890, under the guidance of Walcott, who had seen most of the localities before, examined 

various districts on the eastern side of the Adirondacks from fort Ann, 

south of Whitehall, to Westport. The peripheral area of this part of 

the Adirondacks was found to be a great series of laminated rocks, 

consisting for the most part of white and red, regularly laminated 

gneisses, very frequently garnetiferous, and in lesser quantity of garnetiferous quartz-schist, crystalline limestone, graphitic gneiss, and 

beds of magnetic iron ore, dipping as a whole at rather a flat angle 

toward the east and southeast. The garnetiferous quartz-schists were 

found in rather persistent beds. A graphite mine in the neighborhood of 

Hague is a layer of very graphitic gneiss, comparable, as said by Walcott, to a coal seam in an ordinary bedded succession. Scales of 

graphite are uniformly disseminated through the coarsely crystalline 

limestone, the amount often being very considerable. Below the 

crystalline limestone is a coarse black hornblendic gneiss, the contacts 

between it and the limestone being of a most extraordinary character. 

The plane between them is one of great irregularity. In the limestone 

are contained numerous fragments, and even great bowlders of the 

gneiss, and also for a distance of some feet away from the contact are 

numerous crystals of feldspar. The appearance is such as to suggest 

very strongly that here is an unconformable contact, the limestone 

being deposited along an encroaching shore line. The phenomena are, 

however, probably due to the breaking up of layers of gneiss and veins of 

pigmatite by powerful dynamic movements. In passing from Westport within a short distance appeared coarse gabbro, which continued 

as far as the region was penetrated, near to mount Marcy. This rock 

in the interior is generally massive, but on its outer border grades into 

a regularly laminated rock, resembling in exposure very closely the

laminated gneisses. The whole is, however, clearly an eruptive rock. 

Granite was seen locally associated with the gneisses.

WILLIAMS and VAN HiSE,130 in 1890, examined the western side of 

the Adirondacks. Just as on its eastern side, there was found a peripheral succession of regularly laminated gneisses and crystalline limestones of great thickness. The latter is particularly well seen in the 

neighborhood of G-ouverneur. The contacts between the limestones 

and lower gneiss were found to be almost identical with those on the 

eastern side of the mountains, but the appearance here strongly suggests that the relations have been produced by interior movements of 

the rocks, the irregular contact surface being a contorted one as a result of folding, and the contained fragments broken off and included in 

the limestone by means of dynamic action. The interior of the Adirondacks was here found to consist of gabbro, in every respect like that 

on the east side of the mountains.

In passing inward from the gneissic series this is first found in small 

quantity, then appears more and more abundant, until finally it be.
VAN HISE.J EASTERN UNITED STATES. 399

comes predominant. At Bonaparte lake a contact of the gabbro witli 

the limestone was found which showed all the characteristics of an intrusive rock, the limestone giving evidence of contact action. There 

were found, both in the limestone and in the gabbro areas, smaller areas 

of coarse red granite.

As a result of the reconnaissance it was concluded as probable that 

the Adirondacks core is an eruptive basic rock, which has upthrust and 

intruded itself within the gueissic series. Because of the character of 

the gneissic series, containing quartz-schist, graphitic schist, and 

crystalline limestone, including graphite, it is regarded as having been 

originally clastic. Its present crystalline character and quaquaversal 

arrangement is doubtless due to the intrusion of the gabbro. It thus 

appears that there is in this region a great bedded succession which 

belongs to the Algonkian system. The lowest coarse grained gneiss 

inferior to the limestone perhaps belongs to a still earlier series, but 

this is a point upon which closer studies are needed.

IJTERATURE OF NEW JERSEY.

VANTJXEM and KEATiNG,131 in 1821, state that the country around 

Franklin is composed of syenite which is found in beds or layers of variable thickness, running in a direction parallel to that of th e ridge. A white 

limestone forms a bed with eminently crystalline structure, the inclination, direction, and dip of which are the same as those of the syenite. 

This limestone has been traced for a distance of 8 miles, and, although, 

the limestone is subordinate to the syenite, masses of the latter are found 

in it. At Franklin, next to the syenite, are found masses of gray wacke, 

which, on the road from Franklins to Dr. Fowler's, is seen to be superimposed upon the syenite and is evidently a later formation. About 

a quarter of a mile below the furnace it is covered with a violet limestone which rests upon it in parallel superposition. This limestone and 

that associated with the syenite are not of contemporaneous origin, 

but the blue limestone is a real mantle-formed superposition.

PiERCE,132 in 1822, describes the Highland ranges as primitive, with 

the exception of an isolated transition region. The rocks here included 

are granite, gneiss,'and syenite, while in the transition are found graywacke, graywacke-slate, chlorite-slate, and limestone.

EOGERS (H. D.),133 in 1840, gives a systematic account of the Primary 

rocks of New Jersey. These are almost exclusively of the stratified 

class, consisting of gneiss under all its forms, the granitoid variety 

predominating. Innumerable small veins of feldspathic granite, syenite, greenstone, etc., penetrate the gneiss. The gneiss is comparatively 

seldom of the schistose kind. Mica is deficient, the usual mixture being either feldspar or quartz with a little mica, or these minerals with 

an excess of hornblende, and hornblende and magnetic oxide of iron, 

the latter being so abundant as to be a characteristic constituent. It 

occurs not only as an occasional ingredient of the gneiss, but in great
400 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

dikes or veins penetrating the strata. The massive granitoid gneisses 

of the Highlands are in striking contrast with the gneiss belt of New 

York and Staten island, which reappears at Trenton and ranges through 

Pennsylvania and Maryland, which is distinguished by the prevalence 

of mica and other thinly laminated minerals, imparting to the rock a 

schistose structure or the thinly bedded character of ordinary gneiss. 

The massive strata are, upon the whole, decidedly less than in the 

Philadelphia belt. They are usually highly inclined, the average dip 

exceeding 45°. In many of the principal ridges an anticlinal arrangement is plainly visible.

There are three main axes of elevation in the granitic area rising above 

the secondary sandstones and limestones. The metalliferous veins 

generally coincide with the direction of the strata in strike and dip, 

but they exhibit many minor irregularities, such as frequent change in 

thickness and deviation from the direction of the strata, and are 

regarded as unchanged matter. The gneiss formation of Trenton has 

a steep inclination, about 70° to the southeast, and rests unconformably under the more recent formations, and is regarded as the equivalent of the gneiss of Manhattan island.

The blue limestone belonging to the older secondary strata has often 

a secondary cleavage corresponding with the slate to which it is adjacent. Associated with these limestones are various igneous rocks 

which have locally caused it to become crystalline and have developed 

within it plumbago and various silicates. Often these crystalline forms 

of limestones are associated with the metalliferous veins, which are 

regarded as the cause of its crystalline character.

JACKSON,134 in 1854, maintains that the New Jersey crystalline limestones are of igneous origin.

KiTCHELL,135 in 1856, places the formations of the Highlands in the

Azoic system. These include gneiss, hornblendic, micaceous, feldspathic, 

and quartzose schists, and white crystalline limestone interstratifled 

with seams or layers of magnetic iron ore. These rocks are traversed 

by numerous intrusive dikes of granite and syenite; the strata are 

highly metamorphic; exhibit violent dislocations; their general strike 

is northeast and southwest, the same as the intrusive dikes, and their 

dips southeast. In addition to their distinct stratification they exhibit 

planes of cleavage frequently at right angles to the former and generally inclining toward the northeast at an angle varying from the 

horizontal to 45°. At one place limestone rests unconformably upon 

the gneiss.

OooK, 136 in 1868, places under the Azoic rocks the gneisses, crystalline limestone, and beds of magnetic iron ore. The crystalline limestone in every case is conformable to the gneiss and interstratified 

with it. It is not, as supposed by Eogers, the metamorphosed blue limestone. The iron ores, instead of being igneous, are believed to be true 

beds which were deposited as sediments in the same way as the material
VAX HISS.! EASTERN UNITED STATES. 401

of the gneiss rocks. The gneiss is divided into four principal belts. The 

Azoic formations, with trifling exceptions, are stratified. Usually they 

are inclined a good deal, but the dip varies from zero to 90°. The 

axes of the folds are generally in a northeast and southwest direction. 

Some of the rocks are so thin bedded as to be schistose, while other portions are so thick bedded that for long distances it is almost impossible 

to tell which way the rock dips. The gneiss is cut by veins and dikes 

of trap and granite. The Azoic rocks of Trenton are much more like 

a true gneiss than those of the Highlands. The Potsdam sandstone, 

the base of the Paleozoic, is found resting unconformably upon the 

Azoic gneiss at Franklin furnace and at Green pond mountain. The 

relations of the two rocks are such as to make it certain that the sandstone is later than and unconformably upon the gneiss. The Franklin

furnace sandstone is capped by the blue magnesian limestone, which

is equivalent to the calciferous sandstone of the New York reports.

OooK,137 in 1873, gives the four Azoic belts of New Jersey the names 

Eamapo, Passaic, Musconetcong, and Pequest. In the first and last are 

found numerous bands of interlaminated limestones, but in the others 

these are not known to occur. Lithologically the greater portion of the 

Azoic rock is syenite-gneiss. There is no way of identifying it with the 

Laurentian or Huronian of Canada. As to origin all are agreed that 

these Azoic syenitic gneisses are sedimentary. The crystalline limestone of the Eamapo belt is associated with the serpentine, sometimes 

in large quantity.

OooK,138 in 1883, states that the <rocks of the Highland include granite, syenite, several varieties of gneiss, crystalline limestone, and magnetite, with rare species of various schists and some serpentine. The 

strata dip to the southeast at an angle of from 45° to 80°, although it 

is often difficult to determine the directions of strike and dip positively 

because of the massive character of the rock. The ranges are regarded 

as anticlinal folds in general, although this is not probably true in 

every case, and the valleys are synclinal. The massive syenites, granites, and traps are very limited in quantity, and they are perhaps a part 

of the stratified beds in which stratification has been obliterated, 

although granite and syenite dikes are found traversing the bedded 

gneisses.

BARTON, 139 in 1883, states that at Sparta granite cuts across the 

limestone beds and may be in true veins.

CooK,140 in 1884, finds that besides the southeastern dips northwest 

dips occur. There is difficulty in separating the stratified from the unstratified rocks, as nearly all the glaciated ledges look like massive 

rocks. The relations of the syenite rocks and gneisses are not made 

out and it can not be asserted which are the older, but these granitoid 

and syenitic rocks are surrounded by stratified gneisses and other crystalline rocks. To the Highlands the term Archeau is applied because 

Bull. 86 26
402 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 80.

it does not necessitate any correlation or theory, as would the use of 

Laurentian or Azoic.

BRiTTON, 141 in 1885, states that few, if any, of the ridges are simple 

anticlinal folds, the southeast dips being generally as prevalent on one 

side of the mountain as on the other, though often differing perceptibly in degree. The crystalline limestones do not represent the blue 

magnesiau limestone metamorphosed by granite and syenite. The supposed dikes of granite are strata conformable to the white limestone, 

as are the iron and zinc ore beds contained in it, all geologically older 

than the blue limestone with the quartzites and slates composing the 

Lower Silurian system. The conclusion is now reached that the unstratified rock masses underlie the bedded crystalline rocks, although 

the line of separation is but poorly defined, as the stratified rocks of 

the same mineral composition commonly occur on the sides of the massive area with an apparent gradual passage between the two, and at 

no point was any actual unconformability found, although at some 

places abrupt changes in the lamination have been observed within 

short distances. This leads to the conclusion that the massive beds 

are only so because stratification has been wholly destroyed through 

greater metamorphism. The schistose series commonly have a steeper 

dip along their southern margins than along their opposite sides 5 thus 

the axial planes of the folds are often inclined toward the southeast.

While the Potsdam and Paleozoic rocks are unconfbrmable upon the 

Archean, the newer rocks are tilted in such a way as to show that folding has occurred since they were deposited. At only a few places are 

actual junctions found, the two more important being in Owens island, 

in Sussex county, and at Franklin furnace. At several localities the 

relations are perplexing, for the quartzites and conglomerates are so

heavily feldspatliic that near the junction they appear to grade gradually

into the older rocks, fragments and masses of which are included in them. 

Along the southeastern margin of the Highlands the Silurian is crystalline, including crystalline limestones and hydromica-slates, and here 

the unconformity is much less pronounced, no satisfactory contacts 

being known in JSTew Jersey. At Pompton the slate ledges have nearly 

the same dip and strike as the nearest Archean outcrops. At Peekskill hollow and Annsville cove, in New York, the slates and quartzites 

and crystalline rocks appear to be directly conformable, the strata having been subjected to an overturn and causing the quartzite to dip 

under the older rocks, and it is difficult to say where the line of separation is.

BRITTON, m in 1887, divides the Archean rocks into a massive group 

an iron-bearing group, and a gneissic and schistose group, which is also 

believed to be the order of superposition, although there is a gradual 

change from one sedimentary rock into the other. While the massive 

rocks are but faintly laminated, there is no evidence adducible in favor 

of an igneous origin for them, but all indications point to their deposi-
VAN HIBE.I EASTERN UNITED STATES. 403

tion as sediments of one kind or another, and to the more or less complete obliteration of the bedding planes by excessive metamorphisin. 

The beds of magnetic ore occur in different horizons of the middle 

group, bat never occur in the highest or lowest. In this same group 

the beds of crystalline limestone appear generally to be at a slightly 

higher horizon than the magnetite beds. The highest gneissic and 

schistose group corresponds very well in character with the Montalban 

system of Hunt. These rocks are like those of Trenton and WestChester counties in New York. Among the eruptive rocks are placed 

those which occur in dikes, such as diorite, diabase, kersantite, and 

porphyry.

BKITTON, 143 in 1888, describes as occurring in the Archean of New 

Jersey an organic form, apparently algae, to which he applies the name 

ArclicKophyton newberryanum.

NASON, 144 in 1890, describes the Archean of New Jersey. Here are 

found four types of rock: The mount Hope type, a foliated magnetitic 

gneiss, the magnetite sometimes largely replaced by hornblende, with 

little mica; the Oxford type, foliated hornblende-gneiss, magnetite and 

biotite in places almost wholly replacing the hornblende; the Franklin 

type, a less foliated biotite-gneiss; the Montville type, white or crystalline limestone. The Franklin type differs from the mount Hope and 

Oxford types in that the quartz and feldspar are usually in sharply 

angular grains, which contrast with the roundish grains of these minerals in the first two types. The crystalline limestone is placed under 

the Archean only provisionally. As there are apparently many reasons 

why it should be 'considered of more recent origin, there is greater 

reason for supposing that if a part of it proves to be Archean all will 

not. This rock is found at Montville, Wan ague, Pequest furnace, 

Jenny Jump mountain, Oxford church, and Mendham. No actual contacts between the different groups have been found. The distribution 

of the various types is described in detail. Whether the gneisses are 

sedimentary or eruptive has not been ascertained, but there are many 

localities in which true eruptive granitic rocks inclose within their 

masses fragments of the adjacent schistose and gneissic rocks. Also 

in the Archean is frequently found gabbro which is almost certainly 

of igneous origin. Graphite is found to be widely separated in the 

Archean rocks. At one place, commencing at the old graphite mine 

near South bridge, it is found continuously for 35 miles. A similar 

rock has been found at Ion a island in the Hudson river, 35 miles northeast. Another line is found on Bald hill, and a third graphite gneiss 

is found on a hill east of Pompton station and in part of the range of 

Eamapo mountains. Also, graphite occurs at other places.

NASON/45 in 1891, describes the relations of the white and blue limestones of Sussex county, New Jersey. They are found to grade into 

each other at many points. The white limestone is always associated 

with later granitic eruptions. In passing away from a boss or dike
404 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 88.

the limestone is white, but changes steadily with rapid gradations into 

the blue limestone. Sandstones and quartzites of identical character 

underlie both the white and blue limestone and bind them together. 

The one distinguishing fact which separates the white from the blue limestone is the presence of eruptive rocks. It is therefore concluded that 

the two are identical. As the blue limestone belongs to the Cambrian, 

it is concluded that in this region there are no Archean limestones, as 

has been supposed.

LITEKATURE OF PENNSYLVANIA.

FiNCH,146 in 1824, finds, near Baston, syenite, serpentine, and transition limestone, transition granite, transition clay-slate, and transition 

sandstone.

FiNCH,147 in 1828, finds a section from Chads fork to Westchester to 

include gneiss, mica-slate, hornblende-slate, primitive sandstone, and 

transition quartz rock.

BOGERS (H. D.), 148 in 1858, gives a systematic account of the metamorphic rocks of Pennsylvania. These are divided into three main 

divisions: the gneissic series proper, or Hypozoic; Azoic, or those destitute of relics of life, and Paleozoic. The Hypozoic rocks only are 

placed with the primary. The Azoic schists are regarded as newer 

than the Hypozoic, because of differences in the position of the two sets 

of strata, in condition of metamorphism, and in manner of plication. 

The former dip almost invariably to the southeast, while the gneiss in 

many localities has no symmetrical folding. These dissimilarities imply 

essential differences in the directions and dates of tne crust movements. 

The Azoic rocks, however, when they show the maximum amount of metamorphism, simulate in mineral aspect and structure those of the gneissic 

series. The old strata are then separated into three systems by two 

main horizons, the lower, a physical break between the Hypozoic and 

Azoic; the upper, a life limit denoting the first advent, so far as discovered, of organic beings.

The gneissic rocks are separated structurally into three districts: 

First, the area running southwestward from Trenton, through Philadelphia; second, the area between the Schuylkill and the Susquehanna, 

north of the first area; and, third, the South mountain region, a continuation of the Highlands of New Jersey. The Philadelphia belt is intersected very extensively by eruptive rocks, such as granite, greenstone, 

syenite, and trap. The second or middle belt is sometimes called the 

mica-schist belt, because of the amount of this mineral which it contains. The upper or northern belt of gneiss is regarded as a part of 

the lower Primal rocks and as resting unconformably upon the upper 

gneissic group, the belief being based upon the manner of the flexure 

of the two formations rather than upon actual unconformable contacts.

In the Philadelphia belt there is a general prevalence of the northward dip of the strata, varying generally from 30° to 50°. At Fair-
VANHISE.] EASTEKN UNITED STATES. 405

mount the true dip of the rocks is very steep, although there is a deceptive appearance of a nearly horizontal stratification in thick and almost 

parallel beds; but this is not to be confounded with the genuine stratification or grain of the rock as marked by the general distribution of 

its mica and other minerals. In this belt there are really two groups 

of rocks, which, viewed broadly, constitute one synclinal wave. The 

lower is a harder feldspathic and hornblendic gneiss at the south side, 

dipping northward, and reappearing in steep and multitudinous contortions on the other side of the trough; and the upper is a more micaceous group filling the synclinal center of the trough and compressed 

into lesser folds.

In the middle division the rocks are mostly of the granite-like varieties of feldspathic gneiss, with hard hornblendic gneiss, such as constitute tlie central ridges of the South mountain, These are believed to

be in a series of anticlinal and synclinal waves, and in addition to the 

folds there is a series of folds along which the iron-ore deposits are 

found in V-shaped masses.

The northern or South mountain zone is composed of massive or thickbedded gneisses, with which is no talcose slate, or else the Primal 

white sandstone, the lowest member of the Paleozoic. The limestone 

associated with the gneisses is generally found in the synclinal valley. 

The gneisses are regarded as stratified, dip to the southeast, and, as the 

breadth of the chain is so great, the structure is believed to be due to 

overturn flexures.

On the Delaware section is found the best evidence of unconformity 

discovered between the semicrystalline rocks called Primal and the 

gneiss. In one case here the Primal siliceous slates and quartzites are 

a porphyritic and crystalline quartzose conglomerate. Below this is 

an arch or wave of granitoid gneiss containing injections of syenite; 

and the dip of the gneiss seems also to be steeper than that of the 

Primal conglomerate. The relations are, however, best seen at Durham 

creek. Here at one place the sandstone, slates, and conglomerates rest 

with their beds almost perpendicular to the lamination of the gneiss.

The lower part of the Paleozoic rocks are Primal crystalline schists, 

or the Azoic group; Primal conglomerate; Primal older slate; Primal 

white sandstone, Potsdam of New York. The Primal series contains 

but few eruptive rocks, even trap dikes being uncommon, which is 

regarded as proving that the metamorphism is due to heated gases 

through fissures rather than to the contact of igneous material.

The Primal southern belt is first considered. At Attleboro there is 

no marked discordance between this and the gneissic series which 

is supposed to be older. East of the Schuylkill and in Montgomery 

county, the observer is very liable to confound the lowest Primal beds 

with the uppermost hornblendic feldspathic layers of the adjacent genuine gneiss. West of the Schuylkill the Primal slates are of so crystalline a character that it is sometimes difficult to distinguish the strata
406 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

from certain forms of the more micaceous beds of the true gneissic or 

Hypozoic. It is impossible to subdivide the members of the Lower 

Primal group in southern Pennsylvania, because of a prevailing transverse cleavage, which extensively effaces all clear traces of the original 

bedding, and because of the presence ot innumerable plications, often 

so closely compressed as to appear as only one uniform dip, the anticlinal and synclinal foldings in many cases escaping detection through 

the obscuring influence of cleavage, and because of mutations in the 

composition of the beds. The rocks between the Primal white sandstone and the genuine gneiss then include talcoid siliceous slate, 

talco-micaceous slate, and schistose and quartzose micaceous rock. On 

the Brandywine the massive gneisses and finely laminated material are 

interlaminated in such a way as to lead to the conclusion that the latter are closely infolded in the older metamorphic series. In the Primal 

of Susquehanna and York counties, the true bedding is very obscure, 

being almost obliterated.

In passing southward on the Susquehanna the rocks become steadily 

more crystalline, until they are so altered as to have been hitherto 

mistaken for the true Hypozoic. The precise line of contact of the limestones with the slates is not clearly visible at times j indeed, there 

seems to be no line of sudden, transition. The cleavage planes are in 

general parallel with those of the original bedding. The dips on this 

river are steadily in a southeast direction for a distance of 7 or 7£ miles, 

and it is believed that the rocks consist of many compressed folds which 

repeat the same strata many times over. Southwest of the Susquehanna, 

in the South mountains, in Adams, Cumberland, and Franklin counties, 

is an extensive area which is placed with the Primal series. It is a 

continuation of the Blue ridge of Maryland and Virginia. There are a 

few intrusive rocks, mostly of greenstone and trap. Some of the rocks 

are very crystalline, but none are regarded as belonging to the gneissic 

series. In this series are found limestones associated with iron ore.

LEEDS,149 in 1870, states that on the Gerrnantown railroad, 3 miles 

from Philadelphia, in the micaceous schists are imbedded huge bowlders of hard, compact hornblende rock. They are supposed to be a 

primitive surface formation which was broken up before the deposition 

of the metamorphic rocks of undetermined age.

FRAZER,150 in 1876, describes several sections in York and Adams 

counties. Here are included hydromica-slates and hydromica-schists, 

chloritic rocks, quartzite, quartz-slate, gneissoid mica-schist, limestone, 

and chert. Several sections show an un conformable contact between 

the York limestone and the crystalline schists. The latter usually 

dip at a high angle.

FRAZER, 151 in 1877, describes cross-sections in the counties of York, 

Adams, Cumberland, and Franklin. In South mountain the structure 

is found to be essentially the same as that given by Rogers, except 

that it also contains limestone. In one section is a thickness of over
VAN HIM.] EASTERN UNITED STATES. 407

17,000 feet of quartzite and sandy shale and about 2,000 feet of chloritio 

slates. In another section the rocks observed are quartz-conglomerate-sehist, jaspery quartzites, crystalline schists, and orthofelsites. 

The relations seeni to show an unconformability between the older 

(Huronian ?) orthofelsites and schists and the more recent (Cambrian1?) 

sandstone, but it would seem additionally to imply that the alignment 

of the one system was the result of causes entirely different from and 

anterior to those that formed the other. In another section the rocks 

increase in felsitic character to the southeast and in conglomeratic, 

schistose character to the northwest. It is concluded that the South 

mountain chain is composed of two groups of rocks, the lower consisting of quartz-conglomerates in which quartzite occurs; the upper felsitic in character, containing hydro-mica schists and chlorite-schists. 

The felsite itself ranges from a sandy slate to a coarsely porphyritic

rock.

HUNT, 152 in 1877, states that near Conshohocken. is a belt of Laureutian gneiss identical with that of the South and Welsh mountains, that 

separates the Philadelphia gneisses and mica-schists, which are Montalban., from the Auroral limestone. The Laurentian gneiss is succeeded 

on the northeast by serpentines, chloritic schists, micaceous schists, 

and argillites, which are typical Huronian rocks. The intermediate 

position of the Huronian seems to show that it is below the Montalban. 

The Primal and Auroral are the Lower Taconic of Emmons. South of 

the Susquehanna, South mountain rocks again appear and stretch 

southward to the Potomac. They here consist of Montalban and Huronian rocks. In the southern part of Pennsylvania are bedded petrosilex 

rocks, often jasper-like, which are associated with characteristic rocks 

of the Huronian series, to which they are ajl referred.

PRIME,153 in 1878, describes gneiss and mica-schist in Lehigh county 

as Laurentian. A little west of Seller's quarry the Potsdam sandstone 

and Laurentian rocks are seen in contact. The dips of the two seem 

to be conformable, but this may be wrong, as the exposure is small and 

the gneiss apparently has a slight roll. The gneissic rock is here distinctly bedded.

FRAZER,15* in 1880, includes in the post-Eozoic series of Lancaster 

county calcareous argillites, nacreous slates, hydro-mica-schists, cliikis 

quartzite, and chloritic series. In the Eozoic series is placed the 

mica-schist and gneiss belt. Between this series and the previous one 

there is no certain evidence of nonconformability, the transition from 

one rock to the other being gradual and the line between them difficult 

to define.

. FRAZER,155 in 1880, states that the chloritic series pass into the Peach 

bottom, slates within a breadth of a few hundred yards, and equally 

abruptly into chlorites again, and finally into greenish chloritic quartzite, in all respects like those of the South mountain. If the Peach 

bottom slates are Hudson river age as supposed, a difficulty is here 

presented.
408 PRE-CAMBBIAN EOCKS OF NORTH AMERICA. [BULL. 86.

HALL (CHAS. E.), 156 in 1881, describes Philadelphia county and the 

southern parts of Montgomery and Bucks. The schistose rocks are 

placed in the three belts as divided by Kogers, but there is an intermediate belt between the first and second belts of Eogers. The first 

belt is made up of gray schistose gneiss, composed of quartz, feldspar, 

and brown or black mica, with occasional garnets, interlaminated with 

occasional beds of black hornblendic slate and' fine grained sandy 

gneiss. The second belt is characterized by serpentine, soapstone, 

silvery micaceous garnetiferous schists, light colored thin bedded sandy 

gneisses, with disseminated light colored mica in minute flakes. The 

third belt is composed chiefly of quartz, feldspar, and hornblende. 

The beds are often massive, but usually have thin bands of mica or 

hornblende through them. They are syenitic and gneissic granites 

or granitic gneisses in which is found a peculiar variety of blue 

quartz. The prevailing northward dips of the schists and gneisses 

of the first and second belts do not hold for the third. The Primal 

sandstone (Potsdam), wherever it occurs, invariably rests upon the 

rocks of the third belt, and its sandstones and conglomerates are invariably composed of debris from this belt, and in it is found not a 

single flake of mica, quartz, or other material which can belong to the 

first or second belts. For considerable distances the Primal rocks are 

found between the third belt and the schists of the second belt. At 

the Schuylkill the rocks of the first and second belt rest upon and 

against the rocks forming the third belt. The third belt is regarded 

as Laurentian and the first and second belt are assigned a position 

above the Primal Potsdam sandstone and the Auroral limestone. In 

the midst of the roofing-slates of the Susquehanna river occur Hudson 

river fossils, and the first and second belts are referred to or above the 

Hudson river group, while the third belt is referred to the Laurentian.

LESLEY,151 in 1883, describes in the southern part of Northampton 

county the continuation of the Highlands of £Tew Jersey. There are 

in this region four ranges. In the valleys are limestones, the stratification of which is visible everywhere but is much broken and 

crumpled. The stratification of the gneiss or syenite beds of the mountains is, on the contrary, rarely to be seen and can only be judged from 

topographical features. Dips are hard to find, owing to the general 

decomposition of the rock surfaces of the country, to the amount of 

debris on the surface, to the vegetation, and to the massive and homogeneous character of the beds where the true bedding plane has 

sometimes been made out by observing the parallel arrangement of the 

minerals. The South mountain gneisses evidently belong to a different 

system from the Philadelphia belt and they are comparable with the 

Laurentian system. Why they are not covered by Huronian or Cambrian rocks is not known. If the views of Hall are accepted that the 

Philadelphia belt underlies the Potsdam and overlies the Philadelphia 

syenites, it is hard to see why they do not appear between the Potsdam
VANHISB.] EASTERN UNITED STATES. 409

and gneisses at Soutli mountain. The ridges, instead of being simple 

anticlines, are a series of anticlines and synclines. At Morgan hill 

there is discordance between the dips of the Potsdam and the gneiss, 

showing apparent nonconformity. The syenite rocks underlie the limestones, which may represent residual material which has not been removed by erosion. The crystalline character of these outlying ridges 

of limestone may be explained by the fact that the material has been 

buried 30,000 or 40,000 feet below the surface. At Chestnut hill gap on 

the Delaware, the Potsdam sandstone is sometimes vitreous and over it 

are limestones changed into crystalline dolomites holding serpentines. 

In contact with a dike of coarse granite near the south side of the 

gap the slates are changed into chlorite, mica-slate, and hornblendeslates, but in the coarser grits the original pebbles are seen.

HALL, (CHARLES E.) 158 in 1883, describes many localities of slates, 

gneisses, and granites in the South mountain area,

D'lNViLLlERS, 159 in 1883, states that the. existence of anticlinal and 

synclinal folds in the South mountain belt of Berks county is suggested 

by the alternate anticlinal and synclinal belts of limestone and slate, 

but it is not conclusively proved, for these formations belong to different systems of rocks, and no doubt lie unconformably upon the older 

mountain rocks. The South mountain rocks are gneisses and granites, 

which are of two kinds, a distinctly stratified, thick bedded, massive 

gneiss, and a stratified syenite where hornblende is predominant.. The 

eroded edges of the Potsdam sandstone run along the northern slope 

of the belt overlying the gneissoid rocks.

HALL (C. E.), 160 in 1885, places the syenites of Delaware county with 

the Laurentian. Overlying these are the micaceous and garnetiferous 

schists, these relations being well exposed at Chester creek. The cleavage dip varies from 75° to 90°, but the true dips are nearly horizontal 

and undulating, which fact tends to reduce the hypothetical thickness of 

the crystalline rocks of southeastern Pennsylvania to a minimum. The 

serpentines occupy shallow synclinal basins and are the most recent of 

the metamorphosed rocks. East of the Schuylkill river, outside of Delaware county, the schists rest upon the upturned edges of the Potsdam 

and limestones, proving the relative age conclusively. The serpentines, 

mica-schists, and gneisses are regarded as more recent than the Hudson 

river group. In this schistose series one kind of rock gradually fades 

into the next succeeding kind, which renders a delineation almost impossible.

F KAZEE,, 161 in 1885, states that at Hendersons station, in the Philadelphia region, there is an unconformable contact of the limestone with 

the sandstone; and that in the section here there is a series of gentle 

folds rather than a monoclinal structure, as made out by Hall.

FRAZEii, 162 in 1886, describes the Archean rocks of York county. The 

lowest members of the Archean series here found are the Huronian 

schists, which have a thickness of 14,400 feet. A somewhat arbitrary
410 PRE-CAMBRIAN ROCKS OF NORTH AMERICA.

division is made between the Huronian and the next following age, 

the rocks of which are denominated Azoic schists or phyllites, as they 

can not be certainly assigned either to the Archean or to the Paleozoic. 

A belt of them, is found on either side of the broad Huronian area of 

the crystalline schists.

BAND, 163 in 1889, describes a. section of the crystalline rocks from the 

Triassic of Chester county, Pennsylvania, to the Cretaceous of Few 

Jersey, passing through Philadelphia. The rocks are doubtfully referred to various horizons, running from the Laurentian to the Hudson 

river.

LITERATURE OF MARYLAND.

BUCATEL and ALEXANDER, 164 in 1834, describe the Primary rocks as 

one of the chief divisions. These include the following formations: 

Granite, gneiss, limestone, and serpentine.

AiKiN, 165 in 1834, states that granite and primitive schists are intermingled in every possible manner in the region west of Baltimore, 

the dips being with a good deal of regularity toward the southeast. 

Succeeding the primitive rocks are transition slates, sandstones, 

limestones, and greywackes interstratified with transition limestones.

DuoATEL, 166 in 1839, states that the limestones of Harford and Baltimore counties occur in the valleys. In the northwest part of these 

counties the rocks are argillites, which pass into talcose slates, and 

these are succeeded by granitic aggregates in which hornblende is the 

prevailing rock. 

TYSON, 167 in 1860, classifies the rocks of Maryland into those of 

igneous and aqueous origin. In the former are granite, syenite, massive quartzite, porphyry, amygdaloid, trap (including hornblende rock 

or amphibolite), and serpentine. The rocks of aqueous Origin include 

chemical deposits, among which are limestone and dolomite j mechanical 

deposits, among which are sandstone, conglomerate, breccia, clay-slate, 

shale, and clay; and metamorphic rocks, among which are gneiss, micaslate, hornblende-slate, talc-slate, quartzite, granular limestone, and 

dolomite. The rocks of igneous origin are defined as those which give 

no evidence of stratification. These are found in the area about Baltimore, mingled with the sedimentary rocks. In the limestones in many 

cases the stratification has been obliterated. Gneiss is the most largely 

developed of the. rocks in the central part of the state. While there is 

usually ample evidence of stratification in gneiss, in some localities it 

has been so much altered by the joint action of heat and intrusive 

forces as to have nearly obliterated its stratification planes and cause it 

to resemble granite. The four lowest formations of Maryland are 

eruptive; the fifth formation is composed of gneiss, mica-slate, and 

hornblende-slate, which includes the intrusive rocks of the first four 

formations and a portion of the limestone. These rocks occur as a 

belt in Cecil, Harford, Baltimore, Howard, and Montgomery counties,
v*NHfflB.] EASTERN UNITED STATES. 411

and are bounded on the northwest or, more correctly speaking, pass 

by insensible shades of difference into the talcose slates. Near the 

southwestern limit the prevailing rock is gneiss, which is interlaininated with hornblende-slate. In proceeding northwest mica-slate increases in quantity, and in passing still farther this mica-slate passes 

into talc-slate. The metamorphic limestones are found in two ranges; 

the first, the gneisses and mica-slates; and second, the talcose slates.

WILLIAMS,168 in 1886, describes the gabbros and associated hornblendic rocks of Maryland. These are all found to be of igneous origin 

and the schistose hornblendic rocks the result of metamorphism.

WILLIAMS,169 in 1891, describes the structure of the Piedmont plateau 

in Maryland. The western part is a semicrystalline area consisting 

of phyllites, sandstones, marbles, and but few eruptive rocks. The 

eastern area is completely crystalline. The sedimentary rocks include biotite-gneiss, biotite-muscovite-gneiss, muscovite-gneiss, micaschist, quartz-schist, conglomeratic quartz-schist and dolomitic marble. 

Within this area are very numerous eruptive rocks, including granites, 

gneisses, gabbros, diorites, and basic rocks, such as pyroxenite, Iherzolite, etc. Two sections are described in detail. In the semicrystalline 

rocks a cleavage is developed which much obscures the bedding, and 

the succession may be repeated many times by folds and faults. Between the semicrystalline and Completely crystalline rocks there is a 

somewhat abrupt passage. The structure of the western area can be 

accounted for by a single period of folding, while the eastern area, as 

shown by its implicated structure, must have been wrenched, folded, 

and faulted at different times. It is concluded that the eastern area is 

composed of rocks far more ancient than the western, which extend 

under the latter, forming the floor upon which they were deposited. 

This hypothesis accounts for the difference in crystalline character between the rocks of the two areas, for the abruptness of their contact, 

and, since both series have been subjected to a folding together, for 

their apparent conformity along their contact. As to the age of the 

rocks, it is probable that the Paleozoic should include all the semicrystalline schists, while the holocrystalline rocks east of them would be 

assigned to the Algonkian or Archean.

KEYES,169 in 1891, gives as a supplement to the preceding a section 

across the Piedmont plateau of Maryland. In the Frederick limestone 

of the western semicrystalline rocks are fossils of several types characteristic of the Trenton, and the entire series of limestones and shales 

probably represent the Chazy, Trenton, and Hudson river formations. 

East of the western semicrystalline rocks are contorted gneisses, with 

general westerly dips, which are cut by basic and acid rocks and 

which are believed to have been originally granitic, but through the 

agency of enormous orographic pressure have been squeezed into their 

present gneissic condition, as shown by the mechanical deformations 

through which the grains have gone.
412 PRE-CAMBRIAN BOCKS OF NORTH AMERICA. [BULL. 86.

UTERATUKE OF DELAWAKE.

BOOTH,170 in 1841, includes among the primary rocks gneiss, feldspathic rocks, limestones, serpentine, and granite, the first comprising 

about three-quarters of the area. This region is, without question, 

stratified. The average bearing of the rocks is north 47° east, and the 

dip 70° northwest, but occasional bearings are found which differ widely 

from this, and the dip is vertical. The trap rocks have a dip and 

strike conformable with the gneiss and grade into them. The limestone is a coarse to fine grained crystalline marble, interstratified with 

the gneiss. The serpentine and surrounding rocks are cut by numerous veins of granite. The greater part of the trappean formation possesses a clearly stratified structure and grades by transition into the 

gneiss, but the hornblendic and coarse feldspathic veins do not. The 

variation in the strike and dip of the gneiss is regarded as due to the 

granitic veins or to the serpentine.

CHESTER,171 in 1885, places in the Laurentian the hornblendic rocks 

along the line of the Pennsylvania railroad and the area to the east of 

West Chester. The rock is a dark hornblendic gneiss or amphibolitic 

schist, with which is associated a dioritic or syenitic granite of the 

Pennsylvania survey. The two rocks grade into each other, and probably form varieties of the same eruptive series. North of the Laurentian gneisses, and resting upon them, is a series of mica-schists and 

granitic gneisses, with which are associated bedded granites, serpentines, and hornblende rocks which have been referred to the Montalban, or, with the Laurentian, have been called Azoic. These do not 

form two successive formations, for, while the former is either Laurentian or Huronian, the latter must be placed above the Trenton, and 

possibly above the Hudson river slates. The granite of the State is in 

intrusive beds and in beds which are no more than highly metamorphosed granitic gneiss or mica-schist, the two latter grading into each 

other. Crystalline limestones are found at Pleasant hill, Hockessin, 

and near Centreville. Serpentine is found northeast of Wilmington as a 

dike, running with the micaceous schist. Vitreous quartz and quartzite 

occur as thin or massive seams interstratified with the micaceous rocks. 

The quartzite of the northeast corner of the State, underlying limestone, 

is probably of Potsdam age. The strikes and dips of the crystalline 

rocks are very variable, and this variation is often due to the disturbing action of granitic intrusions. The Laurentian is an extension of 

the third belt of Rogers. The limestones are younger than the Potsdam quartzites, and are regarded as calciferous; the mica-schists and 

gneisses certainly overlie the limestones, and the latter therefore begin 

somewhere in the Silurian, and possibly mount as high as the Devonian.

CHESTER,172 in 1890, describes the gabbros, gabbro-diorites, and hornblende-schists of Delaware and their relations to the surrounding rocks.
VANHISB.J EASTERN UNITED STATES. 413

The gabbro, gabbro-diorites, and hornblende-schists are found to grade 

into each other by imperceptible stages, and the two latter are regarded 

as a metamorphosed product of the former and all of igneous origin. 

These rocks are found at various points in contact with the mica-schists 

and gneisses. Where the eruptive rocks have a schistose structure 

this is in apparent conformity with the foliation of the mica-schists. 

Sometimes the mica-schists appear to dip beneath the eruptive rocks, 

and at other times to overlie them. No evidence was found of any 

bedding not coincident with the cleavage. The unconformity discovered by Hall between the trappean rocks and mica-schists in Delaware county, Pennsylvania, was not found on the Delaware side of 

the line. If the horizontal bedding described exists, it is so obscured 

as to be unrecognizable ; if the mica-schists are considered to lie horizontally the eruptive character of the gabbros, gabro-diorites, and 

hornblende rocks is but the more evident.

GENERAL LITERATURE.

MARTIN,173 in 1886, states that the Tide-water gneiss has mineralogical characters which distinguishes it strongly from the gneisses of the 

northern Laurentian and from the Highlands. In particular the 

abundance of subsilicates and of hydrous silicates is to be noted.

SUMMARY OF RESULTS.

The literature summarized clearly shows that in the central Appalachian area, as in the northern, only general certain results have been 

reached. While there are numerous areas of crystalline rocks, it is not 

clear that many are of pre-Cambrian age. The exceptions are the Adirondacks; the Highlands of New Jersey, with its northern extension 

the Highlands of New York, and its southern extension South mountain of Pennsylvania; and the eastern area of Maryland. A part of 

the northern extension of the Blue ridge is probably also to be here 

included.

The most widespread rock in the Adirondacks is a gabbro, which has 

all of the characteristics of this eruptive rock. The outer border of the 

mass has a well laminated structure, due either to original crystallization or to subsequent metamorphism. This rock is in all respects like 

the Labradorian or Norian of the Canadian survey, to which indeed it 

has been referred by the advocates of the Norian system. The bedded 

succession of gneisses, limestones, and quartzites is in nearly all respects like the original Laurentian described by Logan. While now it 

nowhere has indubitable clastic characters, its beds are such as to show 

that it was originally a sedimentary series. Since the series is not 

closely folded, probably the principal cause of its metamorphism is the 

great batholitic mass of gabbro occupying the core of the mountains, 

which seems to have thrust itself up among the elastics. Whether the
414 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

coarse gneisses which underlie the limestones belong with the latter 

series or represent an earlier one, we have no knowledge. There is, 

then, in this district a possible pre-clastic series, which in its character, 

so far as seen and described, is like the fundamental complex, the true 

Archean; and a clastic series of great but unknown thickness which 

belongs with the Algonkian. That the Adirondack rocks as a whole 

are unconformably below the Potsdam has been unquestioned from the 

first.

The relations of the Highland area of New Jersey with the Potsdam 

sandstone are such as to make it certain that between them there is a 

great structural break. The rocks comprising this area consist largely 

of granite-gneiss, in general very nearly massive, but having a somewhat laminated arrangement of the mineral constituents. The strike 

of the lamination conforms closely with the trend of the area as a whole, 

being east of north and south of west. The gneisses over large areas 

are graphitic. Interlaminated with them are beds of iron ore, and 

apparently of crystalline limestone. They are cut by various basic and 

acidic eruptives.

The weight of opinion in former years has been in favor of the sedimentary origin of this gneissic series. Mather, who gave by far the 

best early descriptions of the district, and Nason, who has recently 

been closely studying the limestones of New Jersey, find that the white 

crystalline limestones which have been regarded as Archean grade 

into the blue limestones which are fossiliferous. These writers regard 

all of the white limestone as parts of a newer series which have been 

metamorphosed either as a result of extreme folding or by intrusive 

masses of granite of later date, with which they are frequently associated. If all of these limestones are excluded from the pre-Canibrian 

and this is a very doubtful assumption, the evidence in favor of the

detrital origin of the Highland area is restricted to the widely disseminated graphite and to the magnetite beds of iron ore. Magnetite is 

widely associated with certain belts of the granite-gneisses of New 

Jersey, but this and its concentration in lenticular masses within the 

gneisses in the form of magnetite can hardly be considered as decisive 

evidence of their sedimentary character. The magnetites associated 

with the basal gabbros of the lake Superior Keweenawan are in purely 

igneous rocks. The graphite of the graphitic gneiss is a point of more 

weight. The absence of graphite as an important constituent over 

large areas in any definitely determined igneous granite-gneiss, bears 

in favor of the sedimentary origin of the gneissic series. If this theory 

proves true, the Highland gneissic series more nearly approaches the 

characters of a massive eruptive than any other metamorphic sedimentary rock known to the writer. Upon the whole, in the regularity of its 

lamination, in its lack of extreme contortion and foliation, and in the 

presence of graphite, the Highland gneiss is not like the fundamental 

complex, the genuine Archean of Canada and the West. However,
VAKHISE.] EASTERN UNITED STATES. 415

there are no certain criteria upon which it can be referred either to 

the Algonkian or Archean. It must be simply classified, so far as present knowledge goes, as pre-Carnbrian.

If it can not yet be decided whether the Highland gneisses are sedimentary the supposed structural divisions of Britton and Nason can 

be regarded as only lithological. Britton's arrangement of a massive 

group in the cores and schistose groups on the outer parts of the ranges 

can be as well explained, as has been repeatedly seen, by the eruptive 

theory of the origin of the series as by the sedimentary. FromNason's 

work it appears that certain varieties of rock have a continuous widespread distribution; but the descriptions show that his various types 

grade into each other instead of being sharply differentiated as supposed. 

Magnetite is the distinguishing characteristic of one type,' and yet, in

order to make out the continuity of tliis belt, rocks have to be classed

with this type, in which hornblende and biotite are the chief basic constituents. The same thing is true of the second type, in which the hornblende, the distinguishing characteristic, is locally almost wholly replaced by magnetite or biotite.

Of the eastern Crystalline area of Maryland nothing can be said as 

to age, except that it is pre-Gambrian.

The work of Mather and Dana in eastern New York and on Man. 

hattan island, the work of Emerson, Dale, Wolff, and Pumpelly in the 

adjacent district in Massachusetts, combined with the paleontological 

work of Walcott, show beyond all reasonable doubt that a considerable part of the crystalline area of southeastern New York, including in 

all probability Manhattan island itself and the so-called Taconics, belong with the Cambrian and post-Cambrian formations. The detailed 

evidence for this is rather for another to consider.

Various other crystalline areas in southeastern Pennsylvania, in 

Maryland and in Delaware, are in large measure metamorphosed Cambrian and post-Cambrian rocks, as shown by the work of Eogers, Hall, 

Williams, and Chester. There are also probably in these areas preCambrian rocks, although often the gradations described between the 

gneissic series, supposed to be pre-Cambrian and the crystalline 

schists supposed to be Cambrian or post-(3ambrian, are so complete as 

to leave the reader quite in doubt as to the reality of the break supposed to exist between them.

Among all the earlier writers on the crystalline rocks of the Middle 

Atlantic states, Mather is distinguished for the fidelity of his descriptions and for the keenness of his insight. While in his great New 

York report of 1843 there are some crude notions, the comprehensive 

general results announced accord to a remarkable degree with the 

views held by the best informed of the geologists who are working in 

this field to-day.
416 TEE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

SECTION HI. THE SOUTHERN ATLANTIC STATES.

LITERATURE OF THE VIRGINIAS.

i

CORNELIUS,174 in 1818, finds west of the Secondary formations ranges 

of granites, schists, and other primitive rocks. The Blue ridge is the 

dividing line between the granite and the limestone country to the westward.

ROGERS (W. B.), 175 in 1840, describes the southern district east of the 

Blue ridge as occupied mostly by rocks of very ancient date, most of 

them believed to be primary. A part of them are in irregular masses, 

and others have regular stratification, but all are alike considered of 

metamorphic origin. Aside from these there occur igneous rocks. The 

more important metamorphic rocks are granite, syenite, gneiss, micaslate, talc-slate, argillaceous sjate, pseudo-gneiss or gneissic sandstone, 

soapstone rocks, micaceous and talcose limestones, and marbles. By 

pseudo-gneiss or gneissoid sandstone is meant rocks which resemble the 

truly crystalline rocks, but which plainly betray their sedimentary origin by the rounded character of the quartz and other constituents which 

compose them. The igneous rocks cut the shales and sandstones of the 

Middle Secondary.

ROGERS (W. B.), 176 in 1841, gives the geological occurrences of the 

primary and metamorphic. rocks. In these, beds of limestone are 

included at various points. Quartz-slate and quartzite are found in the 

Bull Run mountains and other localities,

FoNTAiNE,177 in 1875, describes several sections of crystalline rocks 

which are regarded as pre-Silurian. Among them are argillite, greenstone, and syenite. At a tunnel the contact of the Silurian with the 

argiUite is beautifully exposed and the great contrast of the two systems is well shown.

FoNTAiNB,178 in 1875, describes the central part of the Blue ridge as 

consisting of coarse granites and gneisses of Laurentian age. Along 

the eastern slope of the syenite is a formation of argillites which is covered by a series of mica-slates, schists, and gneisses. The axis is occupied by talcose limestones, qu,artzites, mica-slates, and hydromica-slates 

which closely resemble those in Berkshire county, Massachusetts. In 

this belt are probably two systems, one older than the Primordial, and 

the other metamorphosed Silurian. The unconformity which exists 

between the syenite and argillite apparently shows the latter to be 

Huronian, although its age is not positively determined.

CAMPBELL (J. L.),179 in 1879, states that the Archean rocks of the 

Blue ridge are granite and syenite. They underlie the stratified rocks 

of the region, but are probably more recent than they, being thrown 

upward through them. The bedded rocks resting upon the syenite are 

much metamorphosed and gneissoid in character. These are followed 

by a bed of conglomeratic quartzite and slates, upon which lie unconformably the Primordial rocks.
U.S.GEOLOGICAL SURVEY. 

UNCLASSIFIED PARTLY OR WHOLLY CRYSTALLINE ROCKS 

GEOLOGICAL MAP OF THE SOUTHEA

SHOWING PRE-CAMBRIAN AND CRYSTALLINE R

After M?Gee and Hitchcock
VAN ui8K,j EASTERN UNITED STATES. 417

CAMPBELL (J. L.), 180 in 1880, describes the metainorphic Archean 

rocks along the James river and Kanawha canal as including1 limestones, schists, and quartettes.

CAMPBELL (J. L.),181 in 1880, describes the Archean rocks at James 

river gap as consisting of granulite and syenite, upon which rest much 

metamorphosed beds of conglomeratic quartzite, and over these slates, 

fcjese Archean rocks are unconforinably below the Primordial rocks, 

which contain fragments of slate, crystals of feldspar, epidote, etc., 

more or less waterworn and cemented together. The slates were metamorphosed before they were deposited in the Primordial strata. The 

syenite and granulite are eruptive rocks which have been thrown up 

since the deposition of the Primordial, as is indicated by the fact that 

the stratified rocks dip at a high angle away from the igneous masses, 

and also from the influence of heat exerted upon the overlying slates 

and sandstones. Higher in the series traces are found of inetamorphic 

changes. The syenite and granulite are supposed to. be the result of 

uqueo-igneous fusion and to represent material which is really older 

than the stratified rocks.

FoNTAiNE,182 in 1883, describes the Blue ridge between Turks gap 

and Balcony falls as consisting of Laurentian, Huronian, and Primordial rocks. The first is mostly gneiss; the second mostly hornblendic, 

micaceous, and argillaceous schists; and in the Primordial is found 

Scolithus.

EoGrEBS (W.B.), 183 in 1884, states that the Blue ridge is a continuation 

of the Green mountains of Vermont, the Highlands of New York and 

New Jersey, and the South mountain of Pennsylvania, and, continued 

southward, becomes the Smoky or Unaka mountains of Tennessee. Th e 

rocks consist for the most part of the older metamorphic strata, including gneiss, and micaceous, chloritic, talcose, and argillaceous schists, 

together with masses referable to the earliest Appalachian formations, 

sometimes in a highly altered condition. Innumerable dikes and veins 

of all dimensions, and consisting of a vast variety of igneous materials, 

penetrate this belt, disturbing and altering its strata in a remarkable 

degree. Southern' dips are prevalent throughout the Avhole of the 

region. This is particularly the case in the southeastern or most disturbed side of the belt, but on the northwest side the reverse dips are 

more common. In many cases the ordinary anticlinal and synclinal 

structures are regarded as overturned in a northwest direction, which 

makes the two sides of the fold approximately parallel, and when this 

is not the case gives the northwest sides a deeper dip than the southeastern. In many of the sections the unconformity between the Cambrian and the crystalline metamorphic rocks is unmistakable, the lowermembers of the former being seen to rest on the slope of the ridge, with 

northwest undulating dips on the edges of the southeastward-dipping 

older rocks. In other cases the primal beds, thrown into southeast 

dips in the hills which flank the Blue ridge, are made to underlie, with 

Bull. 86 27
418 PRE-CAMBRIAN ROCKS OF NORTH AMERICA.. [BULL. 86.

more or less approximation to conformity, the older rocks forming the 

central part of the mountain. But even in those instances it is not difficult to discern the true relations of the strata. As examples of the 

phenomena are the sections exposed at Vestals, Gregorys, Snickers, 

and Manassas gaps> and Jeremies run, in the northern part of the Blue 

ridge; and at Dry run, Turks, Tye river, Whites, James river, point 

Lookout, Fox creek, and White-top mountain gaps, in the middle a:r 

southwestern prolongation of the chain.

CAMPBELL (J. L. and JEL D.), 184 in 1884, conclude from an examination of the Snowdon quarries that the core of the Blue ridge is an igneous 

mass belonging to the Archean, and that upon its northwestern slope 

are unconformable beds of slates, sandstones, and conglomerates which 

are Potsdam or Cambrian. They are in a highly metamorphosed condition, and were regarded by Eogers as Huronian, and by the authors as 

pre-Cambrjan, but the discovery of fossils in them, has definitely determined their age. The slaty cleavage of the quarries sometimes corresponds with the planes of original bedding or stratification, but more 

frequently is more or less oblique to the strata.

GEIG-ER and KEITH, 185 in 1891, in discussing the structure of the district about Harpers ferry, state that between the Cambro-Silurian 

shale and the granite-schist there is an unconformity of the ordinary 

type of deposition.

LITERATURE OF NORTH CAROLINA.

OLMSTED,186 in 1824, describes as parallel with the freestone and 

coal formations a great slate formation which extends across the state 

from northeast to southwest, being about 20 miles wide, running 

through Person, Orange, Chatham, Bandolph, Montgomery, CabarriLs, 

Anson, and Mecklenburg counties. Within this district are found 

numerous beds of porphyry, soapstone, serpentine, greenstone, and 

whetstone. Erom Halifax to Person courthouse hardly any kind of 

rock but granite is met.

OLMSTED,187 in 1825, -more fully describes the great slate formation, 

which includes argillite, greenstone, porphyry, novaculite, petrosilex, 

hornstone, black steatite, syenite, etc. Between the great slate formation and the Blue ridge is a granitic district, various limestone beds, 

and a transition formation. The granitic district occupies the whole 

country, with subordinate exceptions, from the slate formation to the 

Blue ridge. The term granitic as here used embraces gneiss and micaslate as well as granite. Among the subordinate beds nou eare so 

numerous as greenstone. In Stokes and Surrey, in. connection with 

the iron ores, are numerous isolated beds of limestone which lie in niicaslate rocks.

MiTCHELL, 188 in 1829, states that of the primitive rocks'of j^orth Carolina, the more ancient lie farther Avest and the more recent in the midland counties. Those of the eastern division are highly crystalline in
VAN HISB.] EASTEEN UNITED STATES. 419

their structure, consisting of gneiss, slate, and schist, with some granite, 

while those of the western division are almost exclusively granite. 

The transition argillite is widespread, and in it occurs most of the gold 

mines.

MiTCHELL, 189 in 1842, describes as primitive formations the granites, 

gneiss, mica-slate, chlorite-slate, hornblende-slate, and talcose-slate, 

quartz-rock, serpentine, and limestone. A vast body of granite traverses the state in a northeast and southwest direction, comprising a 

large part of Person, Caswell, Orange, Guilford, Eandolph, Davidson, 

Rowan, Cabarrus, and Mecklenburg counties; also some of Lincoln, 

Iredell, Davie, Stokes, and Eockiiighani counties. Within this belt is no 

well defined gneiss, micaceous primitive slate, serpentine, or limestone. 

West of this formation are the most ancient primitive rocks, on the 

upper waters of the Dan, Yadkin, Catawba, and French Broad. Here 

are a great variety of granites. Gneiss and slate also occur. All of 

these are interstratified. Limestones are found at three points in 

Stokes county. In Anson and Eichmond counties is a beautiful porphyritic granite. East of the red sandstone in the counties of Cumberland, Wake, Granville, Warren, Franklin, Nash, Johnston, Halifax, 

and Northampton, is another body of ancient primitive rock in which 

granite prevails.

EMMONS (E.), 190 in 1856, gives a systematic account of the crystalline rocks of North Carolina. Eocks of igneous origin are often massive, 

but also frequently are laminated, and laminated rocks are frequently 

called stratified, but this latter term should be restricted to the sedimentary rocks. The metamorphic rocks are excluded from the sedimentary classification because all rocks ma,y become metamorphic, and 

a stratum metamorphic in one locality may not be metamorphic in 

another. The highest proof of the age of rocks is the order of superposition. When this method can be applied it is paramount, but paleontology may be used subject to proper principles. At the base of the 

Paleozoic, under the Silurian, is placed the Taconic.

The granitic formations are regarded as eruptive or pyrocrystalline. 

They form two continuous belts, which cross the state in a northeast 

and southwest direction. The eastern one is the Raleigh belt, and the 

Avestern one the Salisbury and Greensboro belt. Granite is generally 

the underlying rock, but there are cases on record in which it is sliOAvn 

that it is an overlying one. At Warrentou, in Warren county, of the 

Ealeigh belt, it is fouud to overlie gneiss, mica-slate, and hornblende, 

where it is considered to have been projected through fissures in these 

rocks. This eastern belt contains no metallic veins, nor is it cut by trap 

or other instrusive rocks. Its breadth is from 20 to 25 miles.

The Salisbury granite is frequently syenitic, that is, hornblende takes 

the place of mica. This belt is cut by numerous peculiar dike rocks in 

Avhich, when they decompose, the hornblende trap appears in darkgreen stripes, and many, when carefully examined, have assumed the
420 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL.86.

structure of a sediment or a laminated rock, and which often appears 

like the dark-green .slates of the Taconic system. This singular structure of an eruptive rock is interesting and important, as it proves that 

it may be produced in rocks which have been regarded as sediments, 

but which, in these cases, are the farthest removed from rocks of this 

description, and with which water has had nothing to do. The lamina 

are sometimes as thin as paper, and from their appearance can not be 

distinguished from the slates referred to. These dikes are bounded by 

walls of granite, and are frequently only from 6 to 10 inches wide. The 

mineral veins are generally found on the borders of the granite areas, 

usually within 1 or 2 miles of the slate. This western belt is 10 to 14 

miles wide.

Among laminated pyrocrystalline rocks are placed gneiss, micaschist, talcose slates, hornblende, and certain limestones. It is difficult 

to determine the line of demarkation between gneiss and granite, as 

frequently there are passage beds connecting one with the other. As 

to the pyrocrystalline limestones, they certainly occur among the gneiss 

and mica-slate and hornblende-rocks with laminae parallel with them, 

but still they have many characters which belong only to the eruptive 

rocks.

Besting upon the laminated pyrocrystallines, with the granite as a 

substratum, are rocks of sedimentary origin which are supposed to be 

Azoic. Above these are other rocks which have been in the past regarded as Azoic but are now found to be fossiliferous. The older deep 

seated sediments are sometimes distinguished with difficulty from the 

true primary series, their lithological characters very often belonging to 

the same order. It might be doubted whether they were sediments at 

all were it not that they are associated with conformable pebbly beds, 

which is the only proof that these rocks are really sedimentary.

The Taconic rocks are divided into lower and upper parts. The lower 

series contains talcose slates with white and brown sandstones and 

quartz, with granular limestones and associated slates, and with these 

occur hornblende, which makes it difficult to determine where the primary rocks end and the Taconic begins, especially when the pebbly 

beds are absent. Vitrified quartz can not be regarded as always an igneous product, but rather as a deposit of silica from chemical solution. 

The materials composing the belts of detritus are apparently derived 

from the granites, as shown by the fact that the quartz and feldspar of 

these rocks are distinguishable in the brecciated conglomerates.

KERR, J91 in 1867, finds that the slates of western North Carolina 

have an average strike of K. 50 ° B., the dips being high to the southeast, for the most part about 65°. The greatest variations in strike 

and dip are in the central area, where the strata are contorted and 

folded to an unusual degree. This region extends from the Black 

mountains to the southeastern corner o± Clay county. This central 

area is the axis of the state and is composed for the most part of granitic
VAN HJSE.I EASTERN UNITED STATES. 421

and gneisses rocks which are extremely metamorphosed. These rocks, 

as well as the slates and schists, belong to the most ancient of the 

Azoic series, and the Black mountains are the oldest part of this 

Azoic.

KERR, 192 in 1875, gives a systematic account of the geology of North 

Carolina. The Azoic rocks are divided into Hnronian, Laurentian, and 

Igneous. With the Huronian are placed the siliceous and argillaceous 

slates and conglomerates, micaceous and horublendie slates and schists, 

chlorites, quartzites and diorites, with cherty, jaspery and epidotic beds, 

and much specular iron ore. The Lanrentian includes gneiss, granite, 

hornblende slates, etc., while the' Igneous includes granite, syenite, 

porphyry, etc.

The Laurentian occurs in four areas. The Raleigh area is a belt 20 

or 25 miles wide, running northeast from this place to the state line, 

and consisting of light colored and gray gneisses which occasionally 

pass into granite. These are cut by coarse syenite and diorite dikes. 

The second, the Salisbury granite area, is from 10 to 30 miles wide, and 

has an area of about 3,000 square miles. The prevalent rocks are 

syenite, dolerite, greenstone, amphibolite, granite, porphyry, and trachyte. In. it there is no well denned gneiss, mica-slate, serpentine, 

or limestone. The large area, of Mecklenburg syenite is regarded as 

the oldest rock of Forth Carolina, the bottom of the Laurentian. West 

of the Salisbury area is the largest connected area of Laurentian in the 

state, covering not less than 16,000 square miles. It closely.resembles 

the Raleigh area, especially in the southeastern part, where it consists 

of a succession of schists, gneisses, and slates, for the most part thin 

bedded, and only occasionally showing granite-like masses and syenites 

which are generally in the forms of dikes. Belonging with this series 

are probably the interstratined crystalline limestones of Forsyth, Yadkin, and Stokes. The outcrops are generally limited to two or three 

rods in thickness, a few hundred yards in length, and seem to graduate 

into the neighboring gneisses. The fourth considerable area of Laurentian rocks, occupying an area of 3,000 or 4,000 square miles, is west of 

the Blue ridge, between this range and the Smoky mountains. This is 

probably a continuation of the preceding belt, being separated from it 

by a narrow belt of Huronian slates, and like it containing crystalline 

limestones.

The Huronian follows the Laurentian without a break of geological 

continuity. These rocks are found in five principal lines of outcrops. 

These are that east of the Raleigh Laurentian, that between the Raleigh and Salisbury granite, that west of the Salisbury granite or 

King's mountain belt, that of the Blue ridge mountains, and that of 

the great Smoky mountains, called the Cherokee slates. These belts 

are placed with the Huronian because they succeed the, Laurentian, 

and because they differ from them in degree of inetainorphism and 

lithological character, so that the change from one to the other is ob-
422 PRE-OAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 88.

vious along tlie whole Hue of contact. The slates included are often 

highly plumbaceous, sometimes containing as high as 50 per cent 

of graphite, and also contain beds of coarse granular limestone, in 

which is tremolite as well as magnetic iron in bedded veins sometimes 20 feet in thickness. Conglomerate belts a,re common. The 

second Huronian area is the largest, is from 20 to 40 miles Avide, frequently contains quartzite, which often passes into conglomerate, and 

in it are most of the mineral veins. The western dips prevail, but in 

the western part of the tract the dip is east for several miles. This 

belt is bounded on both sides by the Laurentian, on which it lies unconformably and from it its materials were derived. This is the principal area of Emmons's Taconic. The western Huronian area by Sa.fford 

and Bradley has been concluded to be Potsdam and sub-Potsdam. If 

this turns out to be Silurian it is probable that the Cherokee, Blue 

ridge, and King mountain belts are of the same age and therefore postHuronian.

FuRMAN,193 in 1889, describes a section through King's mountain, 

running from 5 miles northwest, and another from the old gold mine 

to the granite. The rocks have a high inclination and consist of interstratified quartzite, limestone, mica-slate, etc., cut by dikes of trap 

and greisen veins.

LITERATURE OF TENNESSEE.

TROOST,194 in 1840, describes the Primordial rocks of Tennessee as 

occurring in detached areas along the eastern side of the state. These 

are granitic and are associated with greywackes, which are fossiliferous. The state line is approximately the dividing line between the 

crystallines and the fossiliferous rocks.

OwEN, 195 in 1842, states that the metamorphic rocks in the Unaka 

mountains dip at a high angle toward the granitic rocks. These relations are supposed to be due to dislocations.

CuRREY,196 in 1857, states that the Great Smoky mountains are of 

granite, gneiss, mica-slate, talcose slate and quartz rock. The sandstones, shales, and slates on the western descent of the mountains are 

regarded as primitive or metamorphic. They are in an inclined position, dipping inwardly toward the center of the mountain, the Primordial rocks appearing to overlie them. No anticlinal or synclinal axes 

are found, and the tilting is explained by faults.

SAFFORD,197 in 1869, places the lowest formations of Tennessee as 

Potsdam and metamorphic. The Ocoee group is at the base of the 

Potsdam and is, so far as known, Eozoic. The metamorphic formations 

are altered rocks, Azoic or Eozoic in part, mountain-making, and many 

thousand feet thick. They include the talcose slate, in part, of Beech 

mountain and Slate face, in Johnson county; gneissoid rocks of Stone 

mountain; the syenitic gneiss of Eoan mountain; the gneiss and micaschist of the Great Baldj the talcose slates and hornblendic beds of 

Ducktown.
VANHIBK.] EASTERN UNITED STATES. 423

The Ocoee or basal division of the Potsdam is Nemimetamorphic, 

Eozoic, mountain-making, and has a thickness of 10,000 feet. Equivalent with, this are the slates and conglomerates of Monroe county, the 

Little Tennessee river, the west fork of Little Pigeon, of Sevier county, of 

the French Broad in Cocke county, of Big Butt, and of Laurel gap of 

Iron mountain, The metamorphic rocks occur in stratified beds, are 

mostly of the variety called gneiss or stratified granite, and all are metamorphic. The line of separation between the metamorphic rocks and 

those to the Avest is sometimes well defined, but often poorly, the rocks 

gradually losing their crystalline characters and running insensibly 

into the adjacent conglomerates and slates. The general line of separation conforms to the Appalachian ridges. The metamorphic beds and 

the other groups all appear to follow the same law of dip and strike. 

The dip is in the main at a high angle to the southeast. The author

has not been able to satisfy himself as to want of conformableness in 

the beds, although in Johnson county the metamorphic gneiss conies abruptly against the limestone; and other similar cases occur, but these 

unconformable junctions are naturally referable to local fractures and 

displacements, and this unconformableness is local and not the rule. 

There is no reason for believing that the metamorphosed beds include 

formations of any more recent date than the Ocoee conglomerates and 

slates, and a portion of them are certainly referable to this group. The 

remainder, although conformable, may be and most likely are older. 

The transitions from the slates and conglomerates to the gneiss and 

mica-schists are well seen at Ducktown and at the Ocoee. There is no 

sufficient reason for referring any of these rocks to the Huronian or 

Laurentian.

BRADLEY, 198 in 1875, describes sections in east Tennessee from Athens 

to Murphy, and from Knoxville to Murphy. The rocks include semimetamorphosed slates, like those of Ocoee, quartzites, crystalline limestones, and gneisses, all being regarded as probably of Silurian age, 

with the possible exception of the massive granite at Marietta, Cobb 

county, Georgia. The Silurian rocks thus include the Ta conic and 

pyroclastic rocks of Emmons.

ELLIOTT, 199 in 1883, states that the mica-schist and gneiss at Jasper 

dips beneath the marble and is therefore metamorphosed Knox sandstone. The porphyritic gneiss of the West Atlantic railway is identical with that at Talking rock, and is a metamorphosed form of the 

Ocoee sandstone.

LITKKATl'RK OF SOUTH CAROLINA.

BuFFiN,200 in 1843, describes as primitive the limestones which enter 

South Carolina at York, west of Kings mountain, and run to Spartanburg. Embracing nearly all the country above the lower falls of the 

river is a granitic region.

TuOMEYj201 in 1848, gives a report on the geology of South Carolina.
424 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [nnu.ge.

rriic mi stratified or igneous rooks underlie the stratified rocks, or are 

pushed up through them, and include granitic and basaltic rocks, being 

generally found in the form of dikes. Discordances between slaty 

cleavage and bedding are found. The crystalline structure of the Primary stratified rocks is supposed to be due to heat which comes from 

the contact of the underlying intensely heated granite. These formations have no invariable order of superposition, although they generally 

overlie each other in the following manner: Clay slate, talcose slate, 

mica-slate, hornblende-slate, gneiss; and associated with these are 

also beds of limestone, quartz, chlorite, slate, and soapstone.

A very massive gneiss, known as "tablerock," on the west side of 

Saluda, rests unconformat)ly upon the slates, and is regarded as evidence of the prior deposition of the slates, and also as evidence of a 

time break between the two. The mica-slates pass by insensible gradations into the talcose slates. The lime rock is interlaminated both 

with gneiss and with mica-slates, the latter occurring at Kings mountain. The quartz rocks are regarded as residual material left by the 

disappearance of the micaceous and talcose portion of the rock. It 

sometimes passes into a conglomerate-like phase, but this is a step 

on the way toward complete crystallization. The quartz rock at times 

passes into itacolumite. The magnetic and hematitic ores are associated mostly with the slates and limestones, and appear as beds 

interlaminated with and grading into them.

LIBBER, m in 1858, describes the rocks of Chester and York districts. 

They are divided into clay-slate, which includes limestone, itacolumite, 

and specular schist; and hornblende-slate, which includes talcose slate 

and mica-slate. The first class, which may possibly be Paleozoic, appears wherever the Tertiary deposits have been removed by erosion. 

It has a dip unconformable to the talcose slate. Itacolumite is described, and below it at times are found specular schist and above it 

limestone. The igneous rocks are divided into trachytic, trappean, 

and granitic rocks. The trachytic rocks include eurite, quartz-porphyry, coarse trachyte, domite, and phonolith; thetra.ppean rocks include diorite, diorite-slate, soapstone (?), talcose trap (?), melaphyre, 

and aphanitic porphyry; the granites include coarse grained granite, 

syenite, and other granite and gneiss.

LIBBER, 203 in 1858, divides the rocks of Union and Spartanburg into 

a Super-itacoluinite, Itacolumite, and Sub-itacolumite groups. The first 

includes limestone. The second includes itacolumite with talcose slate, 

limestone, specular schists, and itacolumite conglomerate. The third 

includes clay-slate, talcose-slate, mica-slate, and gneiss. There is no 

definite proof that the gneiss occupying the lowest position is of sedimentary origin. Indeed there is greater probability that it is, strictly 

speaking, a granite having a parallel distribution of the scales of mica. 

It passes into the ordinary granite, with no distinct boundary between 

the two. The mica-slate overlying the gneiss is of insignificant thick-
VAN BISH.] EASTERN UNITED STATES. 425

ness, as shown by the fact that mining shafts and streams frequently 

cut through it to the gneiss. The dip of the slate is almost always constant to the southeast. It is the predominant position in the country 

for the metalliferous veins. The itacolumite is described in detail. 

Tbe conglomerate-like itacolumites, mentioned by Tuomey, are regarded 

as real conglomerates, with a micaceous and arenaceous cement. The 

pebbles are obscured and elongated, the longest diameters being parallel to the bedding, and they also partake of the schistose structure of 

the matrix in which they are contained. Every stage in the passage 

from-the fine grained rock to the conglomerate with pebbles is seen, 

and there is no question that the itacolumite is a sandstone. The 

eruptive rocks include granites, eurite, and trappean rocks, among 

which are schistose aphanite, aphanitic porphyry, minette, diorite, 

diorite-slate, and saponite. That the schistose rocks here included are 

really eruptive is shown by the manner in which they intrude the 

granitic rocks.

LiEBER,204 in 1859, gives a general account of the rocks of South 

Carolina. The peculiar structure of the schistose aphanites is regarded 

as due to weathering. In the Greenville and Pickens districts the succession includes gneisses, limestones, and mica-schists, the ruling dips 

being southeasterly. Tourney's representation of these rocks as 60 to 

70 miles thick is believed on theoretical grounds to be incorrect. The 

ruling southeasterly dip of the slates are probably due to faults which 

 have repeated the stratified rocks many times. It is concluded that the 

isolated bodies of stratified rocks overlying the gneiss are actually 

islands occupying, with much regularity, the apical lines of certain parallel ridges. It can not be asserted that any of the mica-slate beds exceed 100 feet in thickness and the horizontal slates 25. The talcose 

slate below the itacolumite is frequently highly graphitic. Above the 

talcose slate is limestone, and above this the itacolumibe, the outlines 

of the latter being extremely tortuous. The dike rocks are aphanite, 

porphyritic hornblende rock, eurite, and garnet. A detailed account 

of itacolumite is given.

LiEBER,203 in 1859, definitely states that itacolumite is regarded as 

occupying a constant position, and is taken as a starting point upon 

which to determine the chronology of the Azoic rocks of the southern 

Alleghanies.

LITERATURE OF GEORGIA.

PECK, 20G in 1833, divides the mountain-region rocks into Primitive 

and Transition, the first being on the west, and the boundary between 

the two being the Smoky mountains.

COTTING-, 207 in 1836, divides the primary formation into granite, 

syenite, porphyritic granite, gneiss, mica-slate, talcose sla,te, granular 

limestone or marble, serpentine, greenstone, epidotic gneiss, quartz 

rock, hornblende, and clay-slates. The granite passes by imperceptible
426 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 80.

gradations into the gneiss, beds of the two sometimes alternating, and 

thelatter also passing into the stratified mica-slates. Gneiss also passes 

into the stratified mica-slate, and the mica-slate into talcose slate. The 

graywacke is the beginning of the transition.

LITTLE, 208 in 1875, mentions crystalline rock, presumably primary, 

at various points.

CAMPBELL (J. L.) and RUFFNER, 209 in 1883, divide the Archean upon 

chemical, lithological, and structural grounds into Laureutian and 

Huronian. In the metamorphosed rocks the prevailing dips are toward 

the southeast. It is believed that while they were somewhat plastic ! 

they were folded and overturned, although sometimes left in a vertical 

position, and not infrequently found in a nearly horizontal position, or 

sometimes resting in arches and depressions. In the Ohoccolocco valley 

the railroad passes abruptly to the Lower Silurian rocks. This relation between the Silurian and Archean is attributed to a fault, with a ' 

downthrow of the former.

LITERATURE OF ALABAMA.

TuoMEY,210 in 1850, places the granites, gneisses, and associated \ 

crystalline rocks as primary and metamorphic. The slates sometimes ' 

carry plumbago, and true granite is found only at Talladega.

TuoMEY,211 in 1858, finds in various sections granite, syenitic gneiss, - 

ordinary gneiss, hornblende-slate, mica-slate, talcose slate, and soapstone. In certain localities are found limestones, and also occasionally 

interstratified quartz-rocks occur. Granite is found about Eockford ' 

in large masses.

SMITH,212 in 1875, states that the counties of Chilton, Talladega, Oal- v 

houu, Cleburne, Lee, Tallapoosa, and Elmore lie partly, and Coosa, 

Clay, Randolph, and Chambers wholly, within the Archean region of { 

the state. On account of the absence of fossils, it is difficult to deter- : 

mine the relative ages of the subdivisions of the crystalline rocks. 

Lithologically they are classified into Laurentian, Huronian, and White 

mountain series, following Hunt's characterization of these terms. The 

rocks here included are granite, gneiss, mica-schist, mica-slate, hydromica-slate, clay-slate or argillite, syenite, syenitic gneiss, hornblendeschist, diorite, norite, talcose slate, soapstone or steatite, chlorite-schist, 

quartzite, siliceous slate, itacoluinite, itabarite, jasper, crystalline limestone, dolomite, and igneous rocks. Crystalline limestone occurs in 

Chilton county. It is succeeded in apparent conformity by sernicrystallines 15,000 to 20,000 feet in thickness.

SCHMITZ,213 in 1884, describes a metamorphic region in Alabama as 

covering the whole or parts of counties Chiltou, Coosa, Talladega, Calhoun, Cleburne, Lee, Tallapoosa, Ebnore, Clay, Randolph, and Chambers, with about 5,000 square miles of area. The rocks of this region 

are partly metamorphosed Lower Silurian rocks (Calciferous, Potsdain,
VANHISE.] EASTERN UNITED STATES. 427

and Acadian), partly Upper Azoic rocks (Huroniau), and perhaps 

partly Lower Azoic rocks (Laurentian).

Going at a right angle with the strike, from northwest to southeast, 

is found the following zones, which, however, cannot be sharply separated. (1) Silurian. Crystalline limestones, conglomerates, heavy 

quartzites, and slates (often gold-bearing), semi-metamorphosed. (2) 

Huronian. Mica-slates and schists (with garnets), limestones, coarse 

grained granites, diorites, quartzites, and clay-slates (sometimes gold-

' bearing); the mica-schists often alternating with gneisses; associated 

with graphite and graphitic slates, itacolumite, specular ore, brown

( hematite, etc. (3) Huronian or Upper Laurentian. Gneisses (micaceous 

and hornblendic), granite, diorite, mica-schists, quartzites, slates (some1 times gold-bearing'), associated with chloritic schists and steatites, mica 

with tourmaline crystals, etc. Some of the granites have the charac-

' teristics of eruptive rocks.

GENERAL LITERATURE.

BEITTON,214 in 188C, describes at Natural bridge the contact betAveen 

, sandstones which appear to be under the Potsdam and over the Archean. 

The two are widely unconformable; the sandstone dips 45° to the 

northwest and strikes N. 40° E., while the Archean dips 05° E. and 

strikes N. 5° E. The Archean rocks consist of quartz-bearing syenite 

and granulite, fragments of which are found in the overlying series.

On. the Doe river, in eastern Tennessee, the Archean and basal Si-

. lurian quartzite are in contact. The Archean is a pegmatite, with no

i bedding or lamination. Five hundred feet east of the contact it is a

much contorted hornblendic gneiss and syenite. These rocks are in-

' tersected by a trap dike. The quartzite is thickly bedded and con-

/ tains many pebbles of quartz and much feldspar, so as to make the

rock in places an arkose.

On the French" Broad river are found quartzites like those of the Doriver, which are succeeded by basal crystalline rocks, and near Mare 

shall station begins a stratified micaceous schistose series. The char- 

; acter of the transition between this and the basal Archean rocks was 

not apparent. About Asheville are well, bedded gneisses and micaschists which bear the same relation to the heavily bedded basal Archean 

as do the Westchester county, New York, and Philadelphia gneisses 

to the basal rocks to the westward. These rocks extend to the top of 

mount Mitchell.

SUMMARY OF RESULTS.

The state of knowledge of the crystalline rocks of the southern Appalachians is in a still less advanced condition than that of the middle 

and northern Appalachians.

It is reasonably certain that from northern Virginia to Alabama 

there are large areas which are pre-Cambrian, including much of the
428' PRE-CAMBRiAN ROOKS OF NORTli AMERICA. [BULL. 86.

granite and granitoid gneiss region. Not only this, but, if litholo.gical 

characters are sufficient evidence, parts are Archean; that is, belong 

with the fundamental rocks of Canada and the West; for areas are 

found,which consist of an intricate complex of foliated and contorted 

granite and gneiss cut by or containing masses of basic eruptives o1 

various kinds. In their intensely implicated structure and lack oi 

thoroughly massive characters they give evidence of vast antiquity.

How far the rocks which have been denominated Huronian belong 

with the pre-Cambrian there is no means even of guessing. It is very 

certain tha,t large parts of the rocks called Taconic and Huronian are 

Cambrian, Silurian, or later. When the Cambrian and Silurian have? 

been definitely outlined, whether any of the unmistakable elastics will 

remain to be correlated with the Huronian, or, more accurately, to bes 

placed in the Algonkian, is uncertain.

The disturbances in the southern Appalachians are of a different type 

and, upon the whole, have been less intense than in the central and 

northern regions, as a consequence of which it will be easier to reacli 

definite results here than it has been farther north.

The only really systematic work which has been done is that in Virginia by Rogers; that of Eminons in North Carolina; that of Safford 

in Tennessee, whose work barely reaches the pre-Cambrian rocks; and 

that of Lieber. The last in his earlier reports carefully refrained, froir 

generalizations based upon insufficient evidence, but patiently mapped 

.the rocks lithologically in several counties, and thus gives serviceable 

information unmingled with theories of no value.

In the south, as in New England, occur formations which by contained belts of conglomerates are definitely proved to be of clastic 

origin, and these gradually pass into unmistakable crystalline schists. 

These transitions were clearly described and their meaning definitely 

pointed out by Emrnons and Lieber respectively in 1856 and 1858.

. More remarkable than this is the discovery of Entmons and Lieber 

that hornblende-schists and other schists are metamorphosed eruptives. These rocks are said sometimes to be as thinly laminated as 

paper, and are compared with slates; but their occurrence in dikes 

within the granites, and their gradations into the ordinary massive 

forms, demonstrate them to be later igneous rocks. These conclusions 

were not based upon petrographical work, but upon careful field study. 

The microscope in recent years has shown accurately the method of 

change; but that the change does occur from a massive eruptive rock 

to a thoroughly schistose one was proved beyond doubt by these men 

before 1860.

Emmons and Lieber further appreciated that the granite-gneisses in 

their lithological affinities as well as by actual transitions belong with 

igneous granitic rocks rather than with the sedinientaries. Emmons 

also reached the same conclusion for the South which Emerson demonstrated many years later for the New England states, that there are
HISB.J EASTERN UNITED STATES. 420

wo granites, one of which is more ancient than .the elastics and the 

ther iiitrusives within these. According to Bmmoiis the ancient form 

is predominant, but occasionally granite has been projected through 

issures like other intrusive rocks.

The great discovery that regularly laminated rocks are produced by 

he metainorphism of eruptive rocks as well as from sedimentary rocks 

latiirally carried the discoverer too far in the application of the princi- 

)le. Enmions included in the inetamorphic igneous rocks many micachists, talcose slates, and limestones for which he gave no evidence

hatever. Lieber's discrimination between the metamorphic-igneous

,nd inetamorphie-sedimentary rocks was much more satisfactory. But

Smmons's general statements as to the small value of lamination alone

i rocks as an evidence of origin and the method of stratigraphical

jVork in the crystalline rocks can hardly be improved upon at the pres-

'wiit day. Says this writer: Bocks of igneous origin are often massive,

lut also are frequently laminated, and laminated rocks are frequently

failed stratified, but this latter term should be restricted to the sedijjnentary rocks. The inetamorphic rocks are excluded from the sedilentary classification because all rocks may become metamorphic, and

stratum metamorphic in one locality may not be metamorphic in 

iiother. The highest proof of the age of rocks is the order of superbsition. When this method can be applied it is paramount, but palentology may be used subject to proper principles.

The Primitive rocks from Emmons's point of view are all igneous; 

jfvith aqueous rocks begins the Azoic, the oldest sedimentaries3 and 

ibove the Azoic are rocks which in the past have been regarded as Azoic, 

out are found to be fossiliferous; that is, they constitute the Taconic system. We have here a definite theory as to the order of development of 

:.he earth, the primitive rocks being wholly pyrocrystalline, the Azoic 

stratified rocks being earlier than the dawn of life, and the Taconic 

flocks being the fossiliferous rocks earlier than the Potsdam.

NOTES.

1 First Annual Report on the Geology of the State of Maine, Charles T. Jackson, 

ugusta, 1837, pp. viir, 9-128; 24 plates.

2 Sketch of the Geology of Portland and its Vicinity, Edward Hitchcock. Bost. 

<oc. Nat. Hist., Journal, vol. i, 1834-'37, pp. 306-347; -with a geological map.

Third Annual Report 011 the Geology of the State of Maine, Charles T. Jackson. 

Vugusta, 1839, pp. xiv and 1-276.

4 General Report upon the Geology of Maine, Charles H. Hitchcock. Preliminary 

Report upon the Natural History and Geology of the State of Maine, pp. 146-328.

5 Reports on the Geology of Maine, Charles H. Hitchcock. Seventh'Annual Report 

>f the Secretary of the Maine Board of Agriculture, pp. 223-312, 323-332, 345-352, 

177-382, 388-395, 404-413, 422-430; map.

fi The Geology of Portland, Charles IT. Hitchcock. Proc. Am. Assoe. Adv. ScL, 

ol. xxit, pp. 163-175.

7 Geology of the Region about the Head Waters of the Androscoggin River, Maine, 

I. H. limit iugtou*. Ibid., 26th meeting, pp. 277-280.
430 PRE-CAMBRIAN BOCKS OF NORTH AMERICA. [BOLL. 86.

8 The Geology of the Island of Mount Desert, Maine, Nathaniel Southgate Shater. 

Eighth Ann. Rept. U. S. Geol. Survey, 1886-'87, pp. 987-1061; 13 pis.

9 First Annual Report on the Geology of New Hampshire, Charles T. Jackson. 

Concord, 1841, pp. 164.

10 Final Report on the Geology and Mineralogy of the State of New Hampshire, 

with Contributions toward the Improvement of Agriculture and Metallurgy, Charles 

T. Jackson, pp. vui, 376; with a map and sections.

11 On the Geological Age of the White Mountains, Henry D. and William B. Rogers. 

Am. Jour. Sci., 2d ser., vol. i, pp. 411-421.

12 On the Geological Age of the White Mountains, Charles T. Jackson, Proc. Boat. 

Soc. Nat. Hist., vol. n, pp. 147-148.

13 The Geology of New Hampshire, C. H. Hitchcock, State Geologist; J. H. Hunt- s 

ington,0 Warren Upham, G. W. Hawes, assistants; vol.n, Concord, 1877, pp.684; with^ 

a six-sheet geological map. See, also, by C. H. Hitchcock, ibid., vol.i, pp. 667; with 

maps. First Annual Report on the Geology and Mineralogy of New Hampshire, 

Manchester, 1869, pp. 36, and a map. Second Annual Report on the Geology and , Mineralogy of New Hampshire, Manchester, 1870, pp. 37; map. Report of the Geo-, 

logical Survey of the State of New Hampshire, showing its progress during the year 1 

1870, Nashua, 1871, pp. 82. Report of the Geological Survey of New Hampshire, its . 

progress during 1871, Nashua, 1872, pp. 56, and map. Norian Rocks in New Hamp-" 

shire; Am. Jour. Sci., 3d ser., vol. in, pp. 43-47. Recent Geological Discoveries \ 

among the White Mountains, New Hampshire. Proc. Am. Assoc. Adv. Sci., 21st ' 

meeting, pp. 135-151. Report of the Geological Survey of the State of New Hamp-t 

shire, showing its progress during the year 1872, pp. 15. On the Classification of the^ 

Rocks of New Hampshire. Proc. Bost. Soc. Nat. Hist., vol. xv, pp. 304-309. On 

Helderberg Rocks in New Hampshire. Am. Jour. Sci., 3d ser., vol. vn, 1874, pp." 

468-476, 557-571. Geology of the White Mountains, Appalachia, vol. I, pp. 70-76.

14 Mineralogy and Lithology, Geo. W. Hawes. Geology of New Hampshire, vol. 

in, part 4, pp. 1-262; 12 plates.

15 The Albany Granite, New Hampshire, and its contact phenomena, George W. 

Hawes. Am. Jour. Sci., 3d ser.., vol xxi, 1881, pp. 21-32.

16 Significance of Oval Granitoid Areas in the Lower Laurentian, C. H. Hitchcock. 

Bull. Geol. Soc. Am., vol. I, pp. 557-558 (abstract). Discussion by G. H. Williams.

17 First Annual Report on the Geology of Vermont, C. B. Adams. Burlington, 1845, 

pp.92; with a map. ^

18 Second Annual Report on the Geology of Vermont, C. B. Adams, Burlington, s 

1846, pp. 267.

19 Third Annual Report on the Geology of the State of Vermont, C. B. Adams. Burlington, 1847, pp. 32.

20 Extract from Z. Thompson's Address on the Natural History of Vermont. Preliminary Report on the Natural History of the State of Vermont, Augustus Young, 

Appendix 6, pp. 65-68.

21 Report on the Geology of Vermont, Edward Hitchcock, vol. i, pp. 1-55. See also 

Report on the Geological Survey of the State of Vermont, 1858, pp. 13. On the Conversion of Certain Conglomerates into Talcose and Micaceous Schists and Gneiss, by 

the Elongation, Flattening, and Metamorphosis of the Pebbles and the Cement. Am. 

Jour. Sci., 2d ser., vol. xxxi, pp. 372-392.

22 Azoic Rocks, C. H. Hitchcock. Report on the Geology of Vermont, vol. I, pp. 

452-469, 471-474,533-558.

23 Unstratified Rocks, Edward Hitchcock. Ibid., vol. n, pp. 559-578.

34 Dikes of Chittendeu County, Prof. Thompson. Ibid., vol. n, pp. 579-594.

23 Notes on the Sections, C. H. Hitchcock. Ibid., vol. n, pp. 595-682.

a; Report relating to the Geology of Northern Vermont, S. R. Hall. Ibid., vol. 11, 

pp. 719-730.
I 

VANHISE.] EASTERN UNITED STATES. 431

27 The Geology of Vermont, Charles H. Hitchcock. Proc. Am. Assoc. Adv. Sci. ; 16th 

meeting, -pp. 120-122.

28 On some Points in the Geology of Vermont, T. Sterry Hunt. Am. Jour. Sci., 2d 

ser., vol. XLvi, 1868, pp. 222-229.

29 The Inclusions in the Granite of Craftsbury, Vermont, Calvin McConniek. Proc. 

Phil: Acacl. Sci., 1886, pp. 19-24.

30 Remarks on the Geology and Mineralogy of a Section of Massachusetts on Con- 

. necticut River, with a part of New Hamphshire and Vermont, Edward Hitchcock. 

Am. Jour. Sci., 1st ser., vol. i, pp. 105-116, 436-439; with a map.

31 Sketch of the Mineralogy and Geology of the vicinity of Williams College, Williamstown, Massachusetts, Prof. Chester Dewey. Ibid, vol. i, pp. 337-346; with a 

map.

32 Geological Section from Taconick Range, in Williamstown, to the City of Troy 

' on the Hudson, Prof. Chester Dewey. Ibid., vol. n, pp. 246-248.

33 A Sketch of the Geology, Mineralogy, and scenery of the regions contiguous to 

i the river Connecticut. With a geological map and draAvings of organic remains, 

and occasional botanical notices, Rev. Edward Hitchcock. Ibid., vol. vi, pp. 1-86, 

/ 201-236; vol. vn, pp. 1-30.

34 A Sketch of the Geology and Mineralogy of the Western part of Massachusetts 

and a, small part of the adjoining States, Prof. Chester Dewey. Ibid., vol. vm, 1824, 

pp. 1-60, 240-244, with map.

3fi Notices of the Lead Mines and Veins of Hampshire County, Massachusetts, and of 

the Geology and Mineralogy of that region, Alanson Nash. Ibid., vol. xn, pp. 238- 

f 270, with a map. 

, 36 Report on the Geology, Mineralogy, Botany, and Zoology of Massachusetts, Ed-

 ward Hitchcock, pp. xii and 702, with atlas. See also Report on the Geology of 

Massachusetts, examined under the direction of the government of that State, durfiug the years 1830 and 1831. Am. Jour. Sci., 1st ser., vol. xxii, pp. 1-70, with a geological map. Report on a Reexamination of the Economical Geology of Massachusetts, pp. 139. Section from Boston to the west line of Plainfield. A. Geological and

 Agricultural Survey of the district adjoining the Erie Canal, Albany, 1824, pp. 158- 

163, and a plate. Q

37 Final Report on the Geology of Massachusetts, Edward Hitchcock. 2 vols., pp. 

831, with maps and plates.

38 On the Probable Age and Origin of a Bed of Plumbago and Anthracite occurring 

in mica-schist near Worcester, Massachusetts, C. Lyell. Quart. Jour. Geol. Soc., 

London, vol. I, 1845, pp. 199-202.

39 Proofs of the Protozoic Age of some of the Altered Rocks of Eastern Massachu- 

. setts, from Fossils recently discovered, W. B. Rogers. Proc. Am. Acad., vol. in, pp. 

> 315-318.

40 Geological Section from Greenfield to Charlemont, Massachusetts, C. H. Hitchcock. Proc. Bost. Soc. Nat. Hist., vol. vi, pp. 380-332.

41 The Geology of Marblehead, J. J. H. Gregory. Proc. Essex Institute, vol. n, pp. 

306-311.

43 Section of Rocks at Base of the South Mountain Emory Bed of Chester, Massachusetts, C. T. Jackson. Proc. Bost. Soc. Nat. Hist., vol. x, p. 86.

43 On the Relation of the Rocks in the Vicinity of Boston, N. S. Shaler. Ibid., vol. 

xni, pp. 172-177.

 "On the Relation of some of the Rocks of the Boston Basin, C. T. Jackson. Ibid., 

°vol. xni., pp. 177-178.

45 On the Quartzite, Limestone and Associated Rocks in the Vicinity of Great Barriugton, Berkshire County, Massachusetts, James D. Dana. Am. Jour. Sci., 3d ser., 

vol. iv, pp. 362-370, 450-153; vol. v, pp. 47-53, 84-91; vol. VI, pp. 257-278, with map.

46 On the Geology of the Vicinity of Boston, T. Sterry Hunt. Bost. Soc. Nat. Hist. 

Proc., vol. xiv, pp. 45-49.
432 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

41 Views on the Eozoonal Limestone of Eastern Massachusetts, L. S. Burbank. 

Ibid., vol. xiv, pp. 190-198. See also pp. 199-204.

48 Notes on the Geology of Eastern Massachusetts, W. W. Dodge. Ibid., vol. xvn, 

pp. 388-419. See also, Ibid., vol. xxi, pp. 197-215.

49 Report on the Geological Map of Massachusetts, W. O. Crosby. Boston, 1876, 

pp. 42.

50 Geology of the Nashua Valley, L. S. Burbank. Report on the Geological Map of 

Massachusetts, W. 0. Crosby. Boston, 1876, pp. 43-52.

61 Note on the Helderberg Formation of Bernardston, Massachusetts, and Vernon, 

Vermont, James D. Dana. Am. Jour. Sci., 3d ser., vol. xiv, pp. 379-387. See, also, 

On the Relations of the Geology of Vermont to that of Berkshire. Ibid., vol. xiv, 

pp. 37-48, 132-140, 202-207, 257-264.

52 On the Classification of Rocks, M. E. Wadsworth. Bull. Mus. Conip. Zool., vol. 

v, pp. 275-287.

53 Contributions to the Geology of Eastern Massachusetts, William Os. Crosby, pp. 

286, with a map.

64 The Felsites and the Associated Rocks north of Boston, J. S. Diller. Bull. Mus. 

Conip. Zool., Harvard, vol. vn, pp. 165-180.

65 On the Relation of the Quincy Granite to the Primordial Argillite of Brain tree, 

Massachusetts, M. E. Wadsworth. Proc. Bost. Soc. Nat. Hist., vol. xxi, 1880-1882, 

pp. 274-277.

56 On the Trachyte of Marblehead Neck, Massachusetts, M. E. Wadsworth. Ibid., 

pp. 288-294.

67 The Argillite and Conglomerate of the Boston Basin, M. E. Wadsworth. Ibid., 

vol. xxn, pp. 130-133.

58 Note on a fossil coal plant found at the graphite deposit in mica-schist, at Worcester, Massachusetts, Joseph H. Perry. Am. Jour. Sci., 3d ser., vol. xxix, pp. 157- 

158.

69 On the Geology at Great Barrington, Massachusetts, Alexis A. Julien. Trans. 

New York Acad. Sci., vol, vil, pp. 21-39.

60 Geology of Hampshire County, Massachusetts, B. K. Emerson. Gazeteer of 

Hampshire County, Massachusetts, 1654-1887. Edited by W. B. Gay, Syracuse, New 

York; pp. 10-22.

61 Relations of the Conglomerate and Slate in the Boston Basin, W. 0. Crosby. 

Proc. Bost. Soc. Nat. Hist., vol. xxm, 1884-1888, pp. 7-27.

62 The Geology of Cape Ann, Massachusetts, Nathaniel Southgate Shaler. Niuth 

Ann. Rept. U. S. Geol. Survey, 1887-'88, pp. 529-611; with plates.

63 A description of the "Bernardston Series" of Metamorphic Upper Devonian 

Rocks, Ben K. Emerson. Am. Jour. Sci., 3d ser., vol. XL, 1890, pp. 263-275, 362-374.

w Porphyritic and Gueissoid Granites in Massachusetts, B. K. Emerson. Bull. Geol. 

Soc. Am., vol. i, pp. 559-561, (abstract).

65 The Relation of Secular Rock Disintegration to certain Transitional CrystallineSchists, Raphael Pumpelly. Ibid., vol n, pp. 209-224.

*" Geology of the Green Mountains in Massachusetts, by Raphael Purupeliy, J. E. 

Wolff, T. Nelson Dale, and Bayard T. Putnam, Part 1; submitted in 1889. General 

Structure and Correlation, Raphael Pumpelly.

67 Geology of Hoosac Mountain, J, E. Wolff. Ibid., Part 2; submitted in 1889.

68 Mount Greylock: Its Structural and Areal Geology, T. Nelson Dale. Ibid. Part 3; 

submitted in 1889. See also The Greylock Synclinorium. Am. Geol., vol. vin, 1891, 

pp. 1-7.

69 Report on the Geological and Agricultural Survey of the State of Rhode Island, 

Charles T. Jackson. Providence, 1840, pp. viii, 312; map and plate.

70 A Geological History of Manhattan or New York Island, Issachar Cozzens, jr. 

New York, 1843, pp.114; with map and sections. 

T1 On the origin of flattened and contorted pebbles in rocks of Roxbury, Newport,
YAN HisR.] EASTERN UNITED STATES. 433

>tc., and oil deptli of decomposition of rocks at Dahlonega, Georgia, C. T. Jackson. 

Proc. Bost. Soc. Nat. Hist., vol. vn, pp. 354; see also Alteration in Eoxbury Conglomerate and that of Rhode Island. Ibid., vol. ix, pp. 57.

72 Geology of the Island of Aquidueck, Charles H. Hitchcock. Proc. Am. Assoc. 

Adv. Sci., 14th meeting, 1861, pp. 112-137.

73 A Contribution to the Geology of Rhode Island, T. Nelson Dale. Proc. Bost. Soc. 

Nat. Hist., vol. XXH, 1882-'83, pp. 179-201; with plates.

74 Sketches of a tour in the counties of New Haven and Litchfield, in Connecticut, 

with notices of the Geology, Mineralogy, and Scenery, etc., Benjamin Silliman. Am. 

Jour. Sci.,lst ser., vol. n, pp. 201-235.

75 Geological Notices, W. W. Mather. Ibid., vol. xxi, pp. 94-99; with section. 

7s Sketch of the Geology and Mineralogy, of New London and Windham Counties, 

Connecticut, Wm. W. Mather. Norwich, 1834, pp. 36, and a map.

77 Report on the Geology of the State of Connecticut, James G. Percival. New 

Haven, 1842, pp. 495, and a map.

78 Green Mountain Geology. On the Quartzite, James D. Dana. Am. Jour. Sci., 

3d ser., vol. in, pp. 179-186, 250-256.

79 On the Relations of the Geology of Vermont to that of Berkshire, James D. Dana. 

Ibid, vol. xiv, pp. 37-48,132-140, 202-207,257-264.

80 The Atlantic System of Mountains, C. H. Hitchcock. Appalachia, vol. i, pp. 

11-14 (abstract).

81 Note on the Age of the Green Mountains, James D. Dana. Am. Jour. Sci., 3d ser., 

vol. xix, pp. 191-200.

82 On the Southward Ending of a Great Synclinal in the Taconic Range, James D. 

Dana. Ibid., vol. xxvni, pp. 268-275; with a map.

83 Geological Sections across NCAV Hampshire and Vermont, C. H. Hitchcock. Blill. 

No. 5, Am. Mus. Nat. Hist., pp. 155-179; with a map and 2 plates.

84 The Geology of Northern New England, C. H. Hitchcock; pp. 1-5, 1-17.

85 Second Contribution to the Studies of the Cambrian Faunas of North America, C. 

D. Walcott. Bull. U. S. Geol. Survey, No. 30, pp. 369,33 plates. See also the Cambrian 

System in the United States and Canada. Bull. Phil. Soc., Washington, vol. vi, pp. 

98-102.

88 The Taconic System of Emmons, and the use of the name Taconic in Geologic 

Nomenclature, Charles D. Walcott. Am. Jour. Sci., 3d ser., vol. xxxv, 1888, pp. 

229-242, 307-327, 394-401; with plate.

87 Stratigraphic Position of the Olenellus Fauna in North America and Europe, C. 

D. Walcott. Idid., vol. xxxvii, pp. 374-392; vol. xxxviu, pp. 29-42.

^Discovery of native crystallized carbonate of magnesia on Staten Island, with a 

notice of the geology and mineralogy of that island, James Pierce. Am. Jour. Sci., 

1st ser., vol. i, 1818, pp. 142-146.

8!> An Essay on the geology of the Hudson River, and the adjacent regions, Samuel 

Akerly. New York, 1820, pp. 69; with a section.

' "Geological and Mineralogical notice of a portion of the northeastern part of the 

State of New York, Augustus E. Jessup. Journal Philadelphia Acad. Sci., vol. ir, 

pp.185-191.

91 An Outline of the Geology of the Highlands on the River Hudson, Prof. Amos 

Eaton. Am. Jour. Sci., 1st ser., vol. v, 1822, pp. 231-235.

92 A Geological and Agricultural Survey of the District adjoining the Erie Canal,in 

the State of New York, Amos Eaton. Albany, 1824, pp. 157; with a geological profile.

93 First annual report of the second geological district of New York, Ebenezer 

Emmons. First Ann. Rept. Geol. Survey of New York, pp. 97-150, and a map.

94 First annual report of the geological survey of the third district of New York, 

T. A. Conrad. Ibid., pp. 155-186. 

Bull. 86 28
434 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

95 Report of the geologist of the first geological district of the State of New York, 

W. W. Mather. Second Aim. Rept. Geol. Survey of New York, pp. 121-183.

96 Report of the geologist of the second geological district of New York, Ebenezer 

Eiumous. Ibid., pp. 185-250; map.

97 Second annual report of so much of the geological survey of the third district of 

New York as relates to objects of immediate utility, Larclner Vanuxeni. Ibid., 

pp. 253-286.

98 Third annual report of the geologist of the first geological district of New York, 

W. W. Mather. Third Ann. Rept. Geol. Survey of New York, pp. 69-134.

"Report on the geology of Orange County, W. Horton. Ibid., pp. 135-175.

100 Report on the geology of New York County, L. D. Gale. Ibid., pp. 177-199.

101 Third annual report of the survey of the second geological district, Ebenezer 

Emmons. Ibid., pp. 201-239.

102Fourth annual report of the survey of the second geological district, Ebenezer 

Emmons. Fourth Ann. Rept. Geol. Survey of New York, pp. 259-353.

10S Fourth annual report of the geological survey of the third district, Larclner 

Vannxem. Ibid., pp. 355-383.

104 Fifth annual report of the geological survey of the first geological district, W. W. 

Mather. Fifth Ann. Rept. Geol. Survey of New York, pp. 63-112.

IDS Fifth annual report of the survey of the second geological district, Ebeuezer 

Emmous. Ibid., pp. 113-136.

106 Geology of New York (northern district) Ebenezer Emmons. Albany, 1842, pp. 

438; 17 plates.

107 Geology of New York, part m (central district), Larduer Vanuxem. Albany, 

1842, pp. 307.

108 Geology of New York, part I (southeastern district), William W. Mather. 

Albany, 1843, pp. xxxvii, 655; 46 plates.

1W A Geological History of Manhattan or New York Islaud, Issachar Cozzens, jr. 

New York, 1843, pp. 114, with map and sections.

no Agriculture of New York, Ebenezer Emmons. Albany, vol. I, 1846, pp. 371; 

21 plates. Map separate.

111 Geognostische Skizze der Umgegend von New York, H. Credner. Zeit. d. deutsch. 

Geol. Gesell., Band 17, pp. 388-398, and plate.

112 Geological Sketch of the Neighborhood of Rossie, Thomas Macfarlane. Can. 

Nat., 2d ser., vol. n, pp. 267-275.

113 Report upon the Past and Present History of the Geology of New York Island, 

R. P. Stevens. Annals N. Y. Lyceum Nat. Hist., vol. vm, pp. 108-120.

U4 Notes on the Lithology of the Adirondacks, Albert R. Leeds. Thirtieth Ann. 

Rept. on the N. Y. State Museum of Nat. Hist., by the regents of the University of 

the State of New York. Albany, 1878, pp. 79-109.

116 On the Geological Relations of the Limestone Belts of Westchester County, 

New York, James D. Dana, Am. Jour. Sci., 3d ser., vol. xx, 1880, pp. 21-32,194-220, 

359-375, 450-456; vol. xxx, 1881, pp. 425-443; vol. xxn, 1881, pp. 103-119,313-315, 

327-335.

110 Geological Age of the Taconic Systeiu, Prof. James D. Dana. Quart. Jour. Geol. 

Soc., London, vol. xxxvin, 1882, pp. 397-408; with plate.

117 Remarks on Serpentine of Staten Island, J. S. Newberry. Trans. N. Y., Acad. 

Sci., vol. I, pp. 57-58.

118 The Geology of Port Henry, New York, T. Sterry Hunt. Can. Nat., 2cl serv 

vol. x, pp. 420-422.

119 Note on the Cortlandt and Stony Point Horublendic and Angitic Rocks, James 

D. Dana. Am. Jour. Sci., 3d ser., vol. xxvur, 1884, pp. 384-386.

120 Laurentian Magnetic Iron Ore Deposits from Northern New York, Charles E. 

Hall. Report of the State Geologist for the year 1884, pp. 23-24, with a geological 

map of Essex county.
VANHISK.] EASTEEN UNITED STATES. 435

121 On a Schistose Series of Crystalline Rocks in the Adiroudacks, N. L. Britton. 

Trans. N. Y. Acad. Sci., vol. v, p. 72.

m On the Adirondack Region, A. A. Julien. Ibid., p. 12.

123 A Geological Reconnaissance in the Crystalline Rock Region, Dutchess, Putnam, and Westchester counties, New York, John C. Sinock. Thirty-ninth Ann. 

Rept. of the Trustees of the State Museum of Natural History for the year 1885, pp. 

166-185, with map.

124 Report on Building Stones, James Hall. Ibid., pp. 176-225.

125ThePeridotites of the "Cortlandt Series" on the Hudson river, near Peekskill, 

N. Y*, George H. Williams. Am. Jour. Sci., 3d ser., vol. xxxr, 1886, pp. 26-41. Tim 

Norites of the " Cortlandt Series "on the Hudson river, near Peekskill, N. Y., 

George H. Williams. Ibid., vol. xxxm, 1887, pp. 135-144, 191-199. The Gabbrofl 

and Diorites of the "Cortlandt Series" on the Hudson river near PeekskilJ, N. Y., 

George H. Williams. Ibid., vol. xxxv, 1888, pp. 438-448. The Contact-Metamorphism produced in the adjoining Mica-Schists and Limestones by the Massive Rocks 

of the "Cortlandt Series'" near Peekskill, N. Y., George H. Williams. Ibid., vol. 

xxxvr, 1888, pp. 254-269; with plate.

126Additional Notes on the Geology of Staten Island, N. L. Britton. Trans. N. Y. 

Acad. Sci., vol. vi, pp. 12-18.

127 The Geology of Manhattan Island, James F. Kemp. Ibid., vol. vn, 1887-'88, 

pp. 49-64; with a map.

128 On the Metamorphic Strata of Southeastern New York, Frederick J. H. Merrill. 

Am. Jour. Sci., 3d ser., vol. xxxix, 1890, pp. 383-392.

1211 Based on unpublished field-notes made by Profs. R. Pumpelly, C. D. Walcott, 

and C. R. Van Hise in the summer of 1890.

130 Based on unpublished field-notes made by Profs. George H. Williams and C. R. 

Van Hise in the summer of 1890.

131 On the Geology and Mineralogy of Franklin, in Sussex County, New Jersey, 

Lardner Vanuxem and William H. Keating. Journal Philadelphia Acad. Nat. Sci., 

vol. IT, pp. 277-288.

132 Geology, Mineralogy, Scenery, etc., of the Highlands of New York and New 

Jersey, James Pierce. Am. Jour. Sci., 1st ser., vol. v, 1822, pp. 26-33.

133 Description of the Geology of the State of New Jersey, being a final report, 

Henry D. Rogers, pp. 301, with a map and plate. See also Report of the Geological 

Survey of the State of New Jersey, Henry D. Rogers, 1835, pp. 174.

134 Geologic Relations of New Jersey Franklinite Veins, C. T. Jackson. Proc. Bost. 

Soc. Nat. Hist., vol. iv, pp. 308-309.

135 Report on the Northern Division of the State, William Kitchell. Second Ann. 

Rept. Geol. Survey of New Jersey for 1855, pp. 111-248, with map. 

136 Geology of New Jersey, George H. Cook, pp.899, Avith portfolio of 13 maps.

137 Annual Report of the State Geologist for the year 1873, George H. Cook, pp. 

128.

138 Annual Report of the State Geologist for the year 1883, George H. Cook, pp. 

178, with map.

139 Remarks on Granite at Sparta, New Jersey, N. H. Darton. Trans. N. Y. Acad. 

Sci., vol. n, p. 25.

1 <" Annual Report of the State Geologist for the year 1884, George H. Cook, pp. 

168, with map.

141 On the Archean Rocks, N. L. Brittou. Ann, Rept. of the New Jersey Geol. Survey 

for 1885, pp. 36-55.

112 Report for 1886, N. L. Britton. Ann. Rept. of the State Geologist of NOAV Jersey 

for the year 1886, pp. 74-112. See also On Recent Field Work in the Archean Area 

of northern New Jersey and southeastern New York. School of Mines Quarterly, 

Columbia College, vol. ix, pp. 33-39.

143 On an Archean Plant, N. L. Britton. Trans. N. Y. Acad. Sci., vol. vn, p. 89.
436 PEE-CAMBRIAN KOCKS OF NORTH AMERICA. [Buu,86.

144 Geological Studies of the Archean Rocks, Frank L. Nason. Ann. Rept. of the 

State Geologist of New Jersey for the year 1889, pp. 12-65.

145 The Post-Archean Age of the White Limestones of Sussex County, New Jersey, 

Frank L. Nason. Ann. Rept. of the State Geologist for the year 1890, pp. 25-50, with 

a map and sections. See also Am. Geol., vol. viu, 1891, pp. 166-171.

146 A Sketch of the Geology of the Country near Easton, Pa., with a catalogue of the 

minerals and a map, John Finch. Am. Jour. Sci., 1st ser., vol. vin, 1824, pp. 236-240.

147 On the Geology and Mineralogy of the country near West Chester, Pa.^ F. Finch. 

Ibid., vol. xiv, 1828, pp. 15-18.

148 The Geology of Pennsylvania, Henry Darwin Rogers; 2 vols., 586 pp. and 1046 

pp., atlas of two maps, Philadelphia, 1858. See also, by the same author, Third 

Annual Report of the Geological Survey of the State of Pennsylvania, Harrisburg, 

1839, pp. 118. Fourth Annual Report on the Geological Survey of the State of Pennsylvania, Harrisburg, 1840, pp. 252. Fifth Annual Report on the Geological Exploration of Pennsylvania, Harrisburg, 1841, pp. 179. Classification of the Metamorphic 

Strata of the Atlantic Slope of the Middle and Southern Stages. Proc. Bost. Soc. Nnt. 

Hist., vol. VI, pp, 140-145.

14:1 Bowlders of Hornblendic Rock in Gneiss near Philadelphia, A. R. Leeds. Proc. 

Philadelphia Acad. Sci., vol. xxii, pp. 134-135.

lfi° Report of Progress in the District of York and Adams Counties, Persifor Frazer, 

jr. Second Geological Survey of Pennsylvania, vol. C, pp. 198, with maps and crosssections.

151 Report of Progress in the Counties of York, Adams, Cumberland, and Franklin, 

Persifor Frazer, jr. Ibid., vol. CC, pp. 201-400, with maps and cross-sections.

153 Geology of Eastern Pennsylvania, T. Sterry Hunt. Proc. Am. Assoc. Adv. Sci., 

25th meeting, pp. 208-212.

153 The Brown Hematite Deposits of Lehigh County, Frederick Prime, jr. Second 

Geological Survey of Pennsylvania, vol. DD, pp. 99, with two maps.

154 The Geology of Lancaster County, Persifor Frazer, jr. Ibid., vol. CCC, pp. 350, 

with an atlas of 11 plates and maps.

155 On the Hudson River age of the Peach Bottom Slates and its bearing on the 

Geology of Southeastern Pennsylvania, Persifor Frazer, jr. Proc. Am. Phil. Soc., vol. 

xvni, pp. 366-368.

156 The Geology of Philadelphia County and of the southern parts of Montgomery 

and Bucks, Charles E. Hall. Second Geological Survey of Pennsylvania, vol. C6, pp. 

145, with map and plate.

157 The Geology of Lehigh and Northampton Counties, J. P. Lesley. Ibid., vol. D3; 

vol. i, pp. 1-82, 2 maps.

168 Itinerary note on the South Mountain Gneiss, Charles E. Hall. Ibid., vol. D3; 

vol. i, pp. 215-258.

16!) The Geology of South Mountain belt of Berks County, E. V. d'lnvilliers. Ibid., 

vol. D3; vol. II, p. 441, with 6 maps.

'eoField Notes in Delaware County, Charles E. Hall. Ibid., vol. C5, part 1, pp. 128, 

with a colored map.

161 A Study of one point intheArchean-Paleozoic contact line in Southeastern Pennsylvania, Persifor Frazer. Proc. Am. Assoc. Adv. Sci., 1884, 33d meeting, pp. 394-396, 

with map.

162 General Notes. Sketch on the Geology of York County, Pennsylvania, Persifor 

Frazer. Proc. Am. Phil. Soc., vol. xxiir, pp. 391-410, with a map.

163 A Discussion on the Rocks of Pennsylvania and New York, Theodore D. Rand. 

Trans. N. Y. Acad. Sci., vol. vm, pp. 47-51.

164 Report on the Projected Survey of the State of Maryland, J. T. Ducatel and J. 

H. Alexander. Annapolis, 1834, pp. 39. See also Am. Jour. Sci., 1st ser., vol. xx vn, pp. 

1-38.

166 Some Notices of the Geology of the Country between Baltimore and the Ohio
VAN HIBK.] EASTERN TTNITFJ) STATES.

River, with ;i section illustrating the superposition of the rocks, Dr. William E. A. 

Aikin. Am. Jour. Sci., 1st ser., vol. xxvi, 1834, pp. 219-232.

168 Annual Report of the Geologist of Maryland, J. T. Ducatel; pp. 33.

le? First Report of the State Agricultural Chemist of Maryland, Philip T. Tyson. 

Annapolis, 1860, pp. 145 and 20; map.

i"»The Gabbros and Associated Hornblende Rocks occurring in the Neighborhood 

of Baltimore, Maryland, George H. Williams. Bull. U. S. Geol. Survey, No. 28, pp. 78; 

4 pis.

169 The Petrography and Structure of the Piedmont Plateau in. Maryland, George 

Huntington Williams; with a Supplement on a Geological Section across the Piedmont Plateau in Maryland, by Charles R. Keyes. Bull. Geol. Soc. of America, vol. n, 

pp. 301-322.

170 Memoir on the Geological Survey of the State of Delaware, including the Application of the Geological Observations to Agriculture, James C. Booth. Dover, 1841, 

pp. 188.

'"Preliminary Notes on the Geology of Delaware Laurentian, Paleozoic^ and Cretaceous areas, Frederick D. Chester. Proc. Philadelphia Acad. Sci., 1884, pp. 237-259, 

with a map.

172 The Gabbros and Associated Rocks in Delaware, Frederick D. Chester. Bull. U. 

S. Geol. Survey, No. 59, pp. 45.

173 Remarks on the "Tide Water" Gneisses of the Atlantic Coast Region, D. S. 

Martin. Trans. N. Y. Acad. Sci., vol. v, pp. 19-20.

174 On the Geology, Mineralogy, Scenery, and Curiosities of Parts of Virginia, Tennessee, and the Alabama and Mississippi Territories, etc., with Miscellaneous Remarks, Rey. Elias Cornolms. Am. Jour. Sci., 1st ser., vol. I, pp. 214-226, 317-331.

175 Report of the Progress of the Geological Survey of the State of Virginia for the 

year 1839, William B. Rogers. Richmond, 1840, pp. 161, See also Preliminary Report 

(Virginia) for 1835 and Annual Reports for 1836,1837,1838.

17fi Report of the Progress of the Geological Survey of Virginia for the year 1840, 

William B. Rogers. Richmond, 1841, pp. 132.

177 On some Points in the Geology of the Blue Ridge in Virginia, William M. Fontaine. Am. Jour. Sci., 3d ser., vol. ix, pp. 14-22,93-101.

178 On the Primordial Strata of Virginia, William M. Fontaine. Ibid., vol. ix, pp. 

361-369,416-428.

179 Geology of Virginia Balcony Falls; the Blue Ridge and its Geological Connections; some THeoretical Considerations, J. L. Campbell. Ibid., vol. xvm, pp. 

435-445. See also the Silurian Formation in Central Virginia. The "Virginias, vol. 1, 

pp. 41-45,54-56; and Am. Jour. Sci., 3d ser., vol. xvm, pp. 16-29.

180 The mineral resources and advantages of the country adjacent to the James 

River and Kanawha Canal and the Buchananand Clifton Forge Railway, J. L. Camjibell. The Virginias, vol. I, pp. 2-8, with map.

Wl The geology of the Blue Ridge, etc., at James River Gap, Virginia, J. L. Campbell. Ibid., pp. 86-87, 94.

182 Notes on the Mineral Deposits at certain Localities on the Western Part of the 

Blue Ridge, Wm. M. Fontaine. Ibid., vol. iv, pp. 21-22, 42-47, 55-59, 73-76, 92-93.

183 A Reprint of Annual Reports and Other Papers on the Geology of the Virginias, William Barton Rogers, pp. 832. Accompanied by maps and sections.

184 The Snowdon Slate Quarries. J. L. and H. D. Campbell. The Virginias, vol. v, 

pp. 162-163, 170. See also Geology of the Blue Ridge in James River Gap, Virginia, 

J. L. Campbell. Ibid., p. 145; Geology of the Blue Ridge near Balcony Falls, Virginia; a modified view, John L. Campbell. Am. Jour. Sci., 3d. ser., vol. xxvui, pp. 

221-223; vol. xvm, pp, 435-445.

186 The Structure of the Blue Ridge near Harper's Ferry, H.-R. Geiger and Arthur 

Keith. Bull. Geol. Soc. of America, vol; IT, pp. 155-164..
438 PEE-CAMBRIAN ROCKS OF NORTH AMERICA.

186 Report 011 the Geology of North Carolina, conducted under the direction of the, 

Board of Agriculture, Denison Olmsted. Part 1, pp. 3-44.

187 Report on the Geology of North Carolina, Denison Olmsted. Papers on Agricultural subjects; conducted under the direction of the Board of Agriculture, part 

2, Raleigh, 1825, pp. 87-141.

188 On the Geology of the Gold Region of North Carolina, Elisha Mitchell. Am. 

Jour. Sci., 1st ser., vol. xvi, 1829, pp. 1-19, with a map.

189 Elements of Geology, with an outline of the Geology of North Carolina, Elisha 

Mitchell. 1842, pp. 141, and a map.

190 Geological Report of the Midland Counties of North Carolina, Ebenezer Emmons. New York and Raleigh, 1856, pp. xx and 347; map and 12 plates. See also, 

Report on the Geological Survey of North Carolina, Raleigh, 1852, pp. 182, Ex. 

Doc. No. 13; Report of progress of the present state of the Geological and Agricultural Survey of the State of North Carolina, for 1855.

191 Report of the progress of the Geological Survey of North Carolina, 1866, W. C. 

Kerr. Raleigh, 1867, pp. 56.

193 Report of the Geological Survey of North Carolina, W. C. Kerr, vol. i, pp. 325, 

120. See also Second Report of State Geologist of North Carolina. Raleigh, 1869, 

pp. 57.

193 The Tin Deposits of North Carolina, John H. Furman. Trans. N. Y. Acad. Sci., 

vol. viu, pp. 136-145.

194 Fifth Geological Report on the State of Tennessee, Gerard Troost. Nashville, 

1840, pp. 44, with 3 maps.

195 On the Geology of the Western States of North America, David Dale Owen. 

Quart. Jour. Geol. Soc., London, vol. n, pp. 433-447, with a geological chart.

196 A Sketch of the Geology of Tennessee, with a description of its minerals and 

ores, and of its soils and productiveness and Paleontology, Richard 0. Currey. 

Knoxville, 1857, pp. 128 and vi, and a map.

197 Geology of Tennessee, James Merrill Safford. Nashville, 1869, pp. 551, with a 

map. See also by the same author, First, Second, and Third Biennial Reports, 1856, 

1857, 1859. A Geological Reconnaissance of the State of Tennessee.

198 On the Silurian age of the Southern Appalachians, Frank H.Bradley. Am. 

Jour. Sci., 3d ser., vol. ix, pp. 279-288, 370-383.

iycj The age of the Southern Appalachians, John B. Elliot. Ibid., vol. xxv, 1883, 

pp. 282-298.

200 Eeport of the Commencement and Progress of the Agricultural Survey of South 

Carolina for 1843, Edmund Ruffin. Columbia, 1843, pp. 1-98.

201 Report on the Geology of South Carolina, M. Tuomey. Report of the Geological Survey of South Carolina, Columbia, 1846, pp. 293, with a map. See also Report 

on the Geological Survey of South Carolina; Report on the Geological and Agricultural Survey of South Carolina, Columbia, 1844, pp. 63.

202 First Annual Report on the Progress of the South Carolina Survey for 1856, 

Oscar Montgomery Lieber. Columbia, 1858, pp. 133.

203 Second Annual Report on the Progress of the Survey of South Carolina for 1857, 

Oscar Montgomery Lieber. Columbia, 1858, pp. 145.

204 Third Annual Report on the Survey of South Carolina, Oscar Montgomery Lieber, pp. 223 with a map.

205 A contribution to the geologic chronology of the Southern Alleghanies, Oscar 

M. Lieber. Proc. Am. Assoc. Adv. Sci., 12th meeting, 1858, pp. 227-230.

206 Geological and mineralogical account of the mining districts in the State of 

Georgia, western part of North Carolina, and of east Tennessee, Jacob Peck. Am. 

Jour. Sci., 1st ser., vol. xxm, 1833, pp. 1-10; with a map.

207 Report of a geological and agricultural survey of Burke and Richmond counties, 

Georgia, John Ruggles Cotting. Augusta, 1836, pp. 198.
VAN HME.] EASTERN UNITED STATES. 439"

208 Report of progress of the mineralogical, geological, and physical survey of fcho 

State of Georgia from Sept. 1 to Dec. 31,1874, George Little, 1875, pp. 36.

'2M A Physical Survey extending from Atlanta, Ga., across Alabama and Mississippi, 

to the Mississippi River, along the line of the Georgia Pacific Railway, J. L. Campbell and W. H. Rnffner. New York, 1883, pp. 147; with a map.

210 First biennial report on the geology of Alabama, Michael Tuomey. Tuscaloosa, 

1850, pp. xxxii and 176.

211 Second biennial report on the geology of Alabama, M. Tuomey. Montgomery, 

1858, pp. 292.

212 Report of progress of the geological survey of Alabama for 1874, Eugene A. Sra ith. 

Montgomery, 1875, pp. 139.

213 Contributions to the' geology of Alabama, E. J. Schmitx. Trans. Am. Inst. Min. 

Eng. ; vol. xn, pp. 144-172.

214 Geological notes in western Virginia, North Carolina, and eastern Tennessee, N. 

L. Brittou. Trans. N. Y. Acad. Sciv vol. v, pp. 215-223.
CHAPTEB VIII.

GENERAL SUCCESSIONS AND DISCUSSIONS OF PRINCIPLES. 

SECTION I. LITERATURE.

MACLURE, 1 in 1809, places in the primitive rocks granite, gneiss, 

mica-slate, clay-slate, primitive limestone, primitive trap, serpentine, 

porphyry, syenite, topaz rock, quartz rock, primitive flinty slate, primitive gypsum, white stone; and in the Transition, transition limestone, 

transition tra,p, graywacke, transition flinty-slate, transition gypsum. 

The rocks of the Primitive prevail to the east of the Hudson river. 

Throughout the greater part of the eastern and northern states the 

sea washes the primitive rock, but to the southwest ward the Primitive 

runs in a broad belt as far as Alabama, and between it and the ocean 

is a wide belt of alluvial rocks. The Transition rocks occur in one main 

belt, running in a northeast and southwest direction from New York 

to Alabama, and in several minor belts.

EATON,2 in 1832, places as Primitive rocks granite, mica-slate, hornblende rock, talcose rock, granular quartz, granular lime rock. These 

primitive rocks are all contemporaneous, excepting the granular quartz 

and lime rocks, since they alternate continually. These rocks are destitute of organized remains. Numerous localities are given for each 

class.

EMMONS, (E,),3 in 1855, divides rocks into Pyroerystalline, Pyroplastic, and Hydroplastic.

The Pyroerystalline comprises massive rocks, including granite, syenite, hypersthene, pyrocrystalline limestone, serpentine, rensselaerite, 

octahedral iron ore, and laminated rocks, including gneiss, mica-slate, 

hornblende, talcose-slate, etc., laminated limestone, laminated serpentine. The Pyroplastic rocks comprise Subaerial, including lavas, tufa, 

or volcanic products, and Submarine, including greenstone, porphyry, 

basalt, trap. The Hydroplastic rocks comprise Paleozoic, Mesozoic, 

and Cenozoic. The Paleozoic is divided from the base upward into 

Taconic, Silurian, Devonian, Carboniferous, and Permian. Metamorpliic or Azoic rocks are not recognized as classes, as they may occur in 

all series from the earliest to the latest sediments. That gneiss, micaslate, hornblende, and talcose slate, etc., are metamorphic altered sediments there is no evidence. Azoic is objectionable because it presupposes that our observations have made certain that which must ever 

remain doubtful.

The Pyrocrystalline rocks are due to the consolidation of the earth's 

440
VAX HIM.] DISCUSSIONS OF PRINCIPLES. 441

crush. These roclts iucrease in thickness by additions below. On the 

contractions of these rocks fissures are formed, through, which flow 

fluid material which, are hydroplastic and later. The age of rocks maybe deduced from the perfection of their crystalline state. The preeminently crystalline granites are the product arising from the first 

cooling of the first crust. Granite may or ma.y not be connected with 

the oldest masses of the globe. The granites of the United States are 

of two classes; one more ancient than the Taconic rocks, and others, 

which are later eruptions, certainly as new as the Carboniferous. In 

New England the ancient granites are widespread, but there are also 

found granitic areas which have been erupted from fissures and which 

have overflowed wide areas and whose structure is more or less sheeted. 

It is impossible to draw lines of distinction between the two kinds of 

granite, except when the earlier granite is traversed by the later. The

lamination of the laminated Pyrocrystalline rocks is probably due to 

crystallization. Gneiss, mica-slate, hornblende, and talcose slate are 

so blended that it is difficult or impossible to define their boundaries, 

and they are all regarded as contemporaneous formations.

The oldest Hydroplastic rocks constitute the Taconic system, which 

has a clear and well defined base, rarely obscured by passages into the 

primary schists or the Pyroplastic syenites or granites. This system is 

limited above by the Silurian system, at the base of which is the Potsdam sandstone. The thickness of this system is from 25,000 to 30,000 

feet. Sediments of all systems must necessarily consist of the same 

materials. Sandstones, limestones, slates, conglomerates, and breccias 

must make up the matter which composes them; but a comparison of 

the lower members of the Taconic and the Silurian show a decided 

difference in mineral constitution. The first parta.kes of the primary 

character of the granite, gneiss, mica, and talcose slates of the Pyrocrystalline rocks, from the last two of which it is often difficult to distinguish them, while the materials of the Silurian are derived from the 

Taconic rocks. The Taconic system, from the base upward, comprises 

(1) conglomerates and breccias; (2) limestones; (3) slate of enormous 

thickness; (4) dark-colored Taconic slates; (5) sparry limestones. The 

absence of fossils in the Taconic rocks is thought to be due to the probable absence of animals and plants at the time the Berkshire limestone 

and earlier Taconic rocks were deposited. In the Upper Taconic rocks 

are found remains of both plants and a.nimals. The rocks of the 

Taconic system form a belt on both sides of the Blue ridge. On the west 

it is continuous from Canada East to Georgia. On the east it is wider 

in certain places than on the west side, but its continuity is broken. The 

Taconic system rests then on the following points: The formations of 

the series are physically unlike the Lower Silurian; it supports the 

Lower Silurian unconformably at numerous places; it is a system in 

which life existed, and the remains of organisms are left which a.re 

unlike those of the Lower Silurian; it carries back many stages farther
442 PRE-CAMBI4JAN KOUK8 Ot* NORTli AMERICA. |nuu,8«.

tlie time when life appeared, and represents a period vastly longer tLan 

tlie Silurian, although it may occupy a less superficial area.

LOGAN and HUNT,* in 1855, gave a geological sketch of Canada. Tlie, 

ancient rocks are divided into the Laurentian system and the Cambrian and Huronian system.

The rocks of the Laurentian system are almost without exception 

old sedimentary beds that have become highly crystalline; they have 

been greatly disturbed, and form mountain ranges running about northeast and southwest, and sometimes rising to heights of 800 or 1,000 

meters, and even beyond. The rocks of this formation are the oldest 

known on the American continent, and probably correspond to the 

oldest gneisses of Finland and Scandinavia, and to similar rocks in 

the north of Scotland. The rocks of the Laurentain formation are in 

large part crystalline schists, mostly gneissoid or hornblendic. Associated with these schists are seen heavy stratified masses of a crystalhue rock, which is almost entirely composed of feldspar with a base of 

lime and soda. With these schists and these feldspars are found strata 

of quartzite, associated with crystalline limestones which have a rather 

important place in this formation. The limestones form beds from 1 

meter to more than 100 meters thick, and often present a succession of 

thin beds, intercalated in beds of gneiss or quartzite. The quartzites 

sometimes present themselves under the form of conglomerates, and in 

certain cases have a paste of dolomite. Beds of dolomite or of more 

or less magnesian limestone are often intercalated with pure limestones. 

These schists, feldspars, quartzites, and limestones, such as we have 

.described them, constitute the stratified part of the Laurentian system; 

but there are, furthermore, intrusive granites, syenites, and diorites 

which form quite important masses; the granites are sometimes albitic 

and often contain tourmaline, mica in large flakes, sphene, and sulphate 

of molybdenum. Associated with the limestones are important beds of 

hematite and limonite. Graphite is very frequently disseminated in 

little flakes in the crystalline limestones, and forms also veins having 

sometimes a considerable thickness. Two of these are found near Greuville, on the Ottawa. The graphite exists in three detached bands, 

each having a thickness of about 12 centimeters.

In the Cambrian and Huronian system are found the rocks on the 

north shores of lakes Huron and Superior where are present a series of 

schists, sandstones, limestones, and conglomerates, interspersed with 

heavy layers of diorite, and resting unconforniably on the Laurentian 

system. As these rocks are lower than the Silurian terrane, and as 

they have thus far not yielded a single fossil, they may well be referred 

to the Cambrian system (the Lower Cambrian of Sedgwick). The 

schists of this system, on lake Superior, are bluish, and inclose layers 

of horn flint, having calcareous bands, and whose cracks are often filled 

with anthracite. These rocks are covered with a considerable thickness 

of trap, on which are superposed heavy beds of white and red sand-
VAN ntSE.] DISCUSSIONS OF PRINCIPLES. 443

stone, which sometimes pass into a state of conglomerate, inclosing

globes of quartz and jasper. Beds of a reddish argillaceous limestone

are found interspersed with these sandstones, which are cut through

and covered by a second formation of diorite of great thickness, offering

a columnar structure. This formation, which has a total thickness of

nearly 4,000 meters, is traversed by a great number of trap dikes. In

the corresponding formation of the north shore of lake Huron are found

sandstones having a more vitreous aspect, and conglomerates more

< abundant than on lake Superior, associated, however, with schists and

schistose conglomerates, resembling those which we have just described,

.the whole presenting great masses intercalated with diorite. A layer

/ of limestone having a thickness of 16 meters forms part of this series.

j After the eruption of the interstratified diorites have appeared two

' systems of dikes of diorite, and a third of granite, of an epocli inter-

, mediate between the two latter. The formation of the metalliferous

) veins belongs to an epoch still more recent.

L This Huronian formation is observed over a distance of nearly 150 

> leagues on lakes Huron and Superior.

DANA,5 in 1863, gives an account of the Azoic age. This age is dei fined as the age in the earth's history preceding the appearance of 

animal life. Among the Azoic rocks are included all the rocks that 

are older than the Potsdam sandstone of New York, between which 

.^and the Azoic general, unconformable relations obtain. The Azoic 

: rocks constitute the only universal formatiou. They cover the whole 

Mobe, and were the floor of the oceans and the rocks of all emerged 

land when animal life was first created. But subsequent operations 

over the sphere have buried the larger part of the ancient surface, and 

to a great extent worn away and worked up anew its material, so that 

. the area of the old floor now exposed to view is small. The Azoic 

-'regions include Canada north of the St. Lawrence, reaching northeast 

from lakes Huron and Superior to Labrador, and continuing northwest 

to the Arctic ocean, the Adirondacks of northern New York, a similar 

area south of lake Superior, west of the Mississippi a small area in 

Missouri, the Black hills in Dakota, the Laramie range in Nebraska, 

part of the Ozark mountains in Arkansas; and in northern New Jersey 

Azoic gneiss 7 limestone, and other crystalline rocks containing beds of 

iron ore. The rocks of the Azoic are mostly of the metamorphic series, 

related to granite, gneiss, syenite, and the like, but they embrace only 

the most ancient of these rocks. The Azoic rocks are nearly all crystalline, a few sandstones, slates, and conglomerates being the only 

exceptions. They are remarkable for the small amount of silica they 

contain, as shown in the diorites and labradorite rocks. Prevalence of 

iron ore is another characteristic, and none of the minerals are simple 

silicates of aluminum. While the Azoic rocks are crystalline they 

follow one another in variations and alternations like sedimentary beds 

of later date. Granite or gneiss may lie between layers of slate or
4.4.4 PRE-CAMBRIAN ROOKS OF NORTH AMERICA. [nmx.80.

schist, and quartz-rock may have any place in the series. The Azoic 

rocks are the results of alteration of sedimentary strata, as is shown 

by the fact that schists graduate into true slates, and quartzites into 

sandstones, and conglomerates and gneiss into gneissoid granite, and 

thence to true granite and syenite. As evidence of life in the Azoic 

age are cited the formations of limestone strata, the occurrence of 

graphite in the limestone, the occurrence of anthracite in small pieces 

in the iron-bearing rocks of Arendal, Norway. Crystalline rocks have 

been formed in various ages, those in New England, for instance, longafter the Azoic; hence it is possible that some of the Azoic rocks have 

undergone a second or third alteration subsequent to the original one 

in the Azoic age.

LoG-AN,6 in 1864, gives a general account of the ancient rocks of Canada. He states that the rocks composing the Laurentide mountains in 

Canada and the Adirondacks in the State of New York are the oldest 

in North America. They have been shown to be a great series of strata 

which, though profoundly altered, consist chiefly of quartzose, aluminous and argillaceous rocks, like the sedimentary deposits of less ancient 

times. This great mass of crystalline rocks is divided into two groups 

and it appears that the Upper (Labradorian) rests unconformably upon 

the Lower (Laurentian) series. The united thickness of these two 

groups in Canada can not be less than 30,000 feet, and probably much 

exceeds it. A third Canadian group, the Huronian, has been shown by v 

Murray to be about 18,000 feet thick, and to consist chiefly of quartzites, slate conglomerates, diorites, and limestones. The horizontal^ 

strata, which form the base of the Lower Silurian in western Canada, 

rest upon the upturned edges of the Huronian series, which, in its turn, 

unconformably overlies the Lower Laurentian. The Huronian is believed to be more recent than the Upper Lament!an series, although'; 

the two formations have never yet been seen in contact. ;

The united thickness of these three great series may possibly far 

surpass that of all the succeeding rocks, from the base of the Paleozoic 

series to the present time. We are thus carried back to a period so 

remote that the appearance of theso-called Primordial fauna maybe considered a comparatively modern event. We, however, find that, even 

during the Laurentian period, the same chemical and mechanical processes which have ever since been at work disintegrating and reconstructing the earth's crust were in operation as now. In the conglomerates of the Huronian series there are inclosed bowlders derived 

from the Laurentian, which seem to show that the parent rock was 

altered to its present crystalline condition before the deposition of the 

newer formation, while interstratified with the Laurentian limestones 

there are beds of conglomerate, the pebbles of which are themselves 

rolled fragments of still older laminated sand-rock, and the formation 

of these beds leads us still further into the past.

In both the Upper and Lower Lanrentian series there are several
VAN HISB.] DISCUSSIONS OF PRINCIPLES. 445

zones of limestone, each of sufficient volume to constitute an independent formation. Of these calcareous masses it hits been ascertained that three, at least, belong to the Lower Laurentian. But as 

we do not as yet know with certainty either the base or the summit of this 

series, these three may be conform ably followed by maD y more. Althougl i 

the Lower and Upper Laurentian rocks spread over more than 200,000 

square miles in Canada, only about 1,500 square miles have yet been 

fully and connectedly examined in any one district, and it is still 

impossible to say whether the numerous exposures of Laurentian 

limestone met with in other parts of the province are equivalent to 

any of the three zones, or whether they overlie or underlie them all. 

As evidence of life in the Laurentian limestone, are graphite, great 

beds of iron ore, and the presence of recognizable organic forms resembling Stroinatopora.

HUNT,7 in 1867, again characterizes the Laurentian and Huronian 

rocks.

Under the name of Laurentian terrain, the Geologic Commission of 

Canada at first comprehended two distinct series of rocks, one resting 

unconformably on the other, which it afterward distinguished as Lower 

Laurentian and Upper Laurentiau or Labradorian. The first of these 

two series corresponds to the primitive gneiss (Urgneiss) of Scandinavia 

and of the west coast of Scotland. After carefully studying this ancien t 

( gueissic system of North America, the Geologic Commission of Canada 

gave it the name of Laurentian system, taken from the Laurentide 

mountains. As early as 1855 the conviction was expressed that it is 

identical with the primitive gneiss of European countries, an identity which afterwards was established by Murchison for Scotland. 

More recently, Gumbel and vou Hochstetter, after an exhaustive 

study of the old gneiss of Bavaria and Bohemia, enunciated its identity with the Laurentian terrain of Canada, a conclusion which the 

former of these scientists, moreover, supported by a comparison of the 

organic remains of the two regions.

The Lower Laurentian is composed of crystalline schists, a large part 

of which are gneiss, at times granitoid, with quartzites often conglomerates, amphibolic and micaceous schists, pyroxenic rocks, ophiolites 

and limestones sometimes niagnesiau. These limestones, ordinarily 

very crystalline, are found united in. three great distinct formations, 

each having a mean volume of 1,000 to 1,500 feet, and separated by still 

more considerable masses of gneiss and quartzite. The measured thickness of this series on the Ottawa exceeds 20,000 feet, which is probably far from representing the total volume of the system, which, in 

Bavaria, is supposed to attain not less than 90,000 feet. In Hastings 

county, to the north of lake Ontario, there is found resting conformably 

on Laurentian gneiss a series of at least 20,000 feet of crystalline 

schists, comprising a great thickness of impure limestones and calcareous schists, and terminating in a heavy mass of dioritic rocks. It
446 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

seems established that this series, which differs sensibly by the succession of the beds and by its lithological characters from that described 

above, belongs also to the Lower Laurentian, of which it would form a 

higher member j and thus the known thickness of this system in Canada 

would rise to at least 40,000 feet.

The Upper Laurentian or Labradorian terrain is found resting, 

in the form of patches, unconformably on the Lower Laureutian, 

both on the Hastings series and on the Ottawa series, where it often 

occupies a width of several miles. It is found at intervals from lake 

Huron to the coasts of Labrador, and is everywhere recognized by its 

lithological characters. This Labradorian terrain inclosed gneiss with 

orthose, with quartzites and crystalline limestones, but its predominating element is an anorthosite, or rock composed essentially of a 

feldspar of the sixth system, with a mixture of pyroxene, often assuming the form of hypersthene. This anorthosite is sometimes gneissoid, 

and even fine grained; but it assumes rather often a granitoid structure, 

with great cleavable forms in the feldspar. The latter is ordinarily andesite or labradorite, of which it sometimes presents fine opalescent 

varieties resembling those brought from Labrador. The thickness 

attained by the Upper Laurentian terrain is not certain, but it probably exceeds 10,000 feet. The Lower Laurentian presents nothing that 

resembles the anorthosites of the Upper Laurentian, which form the 

highest summits of the Adirondacks, and seems to be identical with the 

hypersthenites of the Hebrides of Scotland, described by MacCulloch. 

The limestones of the Lower Laurentian of Canada inclose organic 

remains, principally belonging to an organism studied and described 

by Dawson, who has given it the name of Eozoon canadense.

The Lower Laureutian terrain is affected by many undulations that

have upraised the beds, rendering them at times almost vertical. The 

mean direction of these foldings is about north and south, but secondary undulations from east to west appear in the region north of the 

Ottawa, the only one where thus far it has been possible to study the 

intimate structure of this terrain. The beds of the Upper Laurentian 

also are upraised at high angles, but the structure of this terrain, which 

has evidently undergone part of the movements that affected the lower, 

has not yet been studied. The lower terrain is traversed ia several 

localities by igneous rocks, and there have been ascertained at least 

four epochs of effusion, three of which are anterior to the Silurian 

period. These eruptive rocks are syenites, quartziferous porphyries, 

and dolerites.

Under the name of Huroniaii terrain is designated a series of rocks, 

more or less altered, resting unconformably on the Lower Laurentian terrain, and probably also on the Labradorian terrain. This 

series is composed of quartzites, of more or less chloritic or epidotic 

schists, sometimes with impure serpentines, and with diorites, which 

constitute very important masses in the series. The quartzites, as well
' VANHISE.] DISCUSSIONS OF PRINCIPLES. 447

as the ehloritic schists, often inclose rolled pebbles, many of which are 

derived from, the Lanrentian gneiss. This Huronlan terrain comprises, 

moreover, a band of about 300 feet of granular limestone, which is impure and often very siliceous. The Hnronian terrain on lake Huron 

has a^thickness of about 18,000 feet. It is also found on the Ottawa, 

and from there it extends to the west of the Mississippi, though covered in large part by Paleozoic terrains. It does not seem, to exist in 

the eastern region of Canada, but recent observations made on the 

island of Newfoundland and in Nova Scotia have demonstrated there 

the existence of rocks that have been referred to this old terrain, which 

tor the rest seems to correspond to the primitive schists (Urschiefer) of 

c Scandinavia. No fossils have yet been found in this terrain. Consid- 

) erable masses of schistose hematitic iron ore are inclosed in this Huro-

/ man terrain on the northeast shore of lake Superior, and in still 

greater abundance at the south, where the famous iron mines of Mar- 

( quette are found. This terrain is more or less affected by undulations 

\ anterior to the Silurian epoch.

/ DANA, 8 in 1872, states that lithological evidence for the chronological arrangement of the crystalline rocks of New England means 

nothing until tested by thorough stratigraphical investigation. This 

evidence means something, or probably so, with respect to Laurentian 

rocks, but it did not until the age of the rocks, in their relations to 

others, was first strati graphically ascertained. It may turn out to be

/' worth, something as regards later rocks when the facts have been carefully tested by stratigraphy. A fossil is proved, by careful observa-

< ' tion, to be restricted to the rocks of a certain period before it is used 

and then cautiously for identifying equivalent beds. Has any one 

proved by careful observation that crystals of staurolite, kyanite, or 

/andalusite, are restricted to rocks of a certain geological period?

j DANA,9 in 1876, gives an account of Archean time. The Archean 

time includes an Azoic and an Eozoic era, though not yet distinguished 

in the rock. The Azoic age is the era in which the physical conditions

1 were incompatible with the existence of life. But this era, so far as 

now known, is without recognizable records; for no rocks have yet 

been shown to be earlier in date than those which are now supposed to 

have been formed since the first life began to exist. The Archean 

rocks of North America are mostly crystalline or metamorphic rocks, 

and their beds stand at all angles, OAving to the uplifting and flexing 

which they have undergone. Where the Silurian strata overlie them, 

the two are unconformable, the latter being often spread out in horizontal beds over the upturned edges of the Archean rocks.

The areas of the Archean include those which have always remained 

uncovered; those which have been covered by later strata, but from 

which the superimposed beds have been removed by erosion, and those 

like the last, which in the course of mountain-making have been pushed 

upward among the displaced strata. The principal areas are the great
448 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULI, :«.

northern, to wliicli belong the lake Superior region and properly the 

Adirondack area; the area along the Appalachian line, including the 

Highlands of New York and New Jersey, and the Blue ridge of Pennsylvania and Virginia; the Atlantic coast range, including areas in 

Newfoundland, Nova Scotia, and eastern NeAv England; isolated areas 

of the Mississippi basin, in Missouri, Arkansas, Texas, and the Black 

hills; the Eocky mountains series, embracing Wind river, Laramie, and 

other summit ranges, and the Pacific coast range of Mexico.

The Archean era is divided into two periods, the Laurentian and the 

Huronian. The estimated thickness of the former is 30,000 feet, and of 

the latter from 10,000 to 20,000 feet. The Laurentian rocks are metamorphic or crystalline, with few exceptions, and include granite, gneiss, 

mica-schist, hornblende, and pyroxenic rocks, beds of crystalline limestone, quartzite, conglomerate, and labradorite. The Laurentian beds 

are altered sedimentary rocks of the ordinary character, as the schists 

grade into true slates, the quartzites into sandstones, and conglomerates and gueisses into gneissoid granites. No distinct remains of plants 

have been observed. Graphite is very abundant. Only the lowest 

division of animal life, such as the Ehizopods and Protozoans, occur. 

This is shown by the occurrence of the fossil JEozoon canadense. The 

Huronian includes the series on the north shore of lake Huron composed of slates, conglomerates, quartzites, layers of jasper and chert, 

with quartz and jasper conglomerates, limestones, beds of diorite which /. 

graduate into syenite or epidote, and also other areas which have been 

placed as the equivalent of this series on lithological grounds.

KING-, 10 in 1878, states that in the Archean outcrops of the fortieth 

parallel one can not fail to notice the widespread simplicity of petrotogical forms, the prevalence of granites, granitoid gneisses, and dioritic metamorphic rocks, the paucity of argillites, quartzites, limestones, 

and zirconiferous and staurolitic schists, the infrequence of large bodies 

of magnetic, specular, or spathic iron, and the complete absence of 

corundum, chrysolite, serpentine, steatite, pyroxene rocks, the true 

nacreous schists, and other minor forms observed in the Appalachian 

system.

Without doubt, the most interesting laws which come out of the 

comparison of these exposures are, that, when considered in depth, from 

the uppermost limits of our so-called Huronian to the lowest Laurentian exposure, there is, first, a regular, steady increase of the intensity of metamorphism, and, secondly, a pretty regular increase in the 

thickness of individual members of the series. The lowest Laurentian 

aplitic granitoid bodies of the Laramie hills are the heaviest beds and 

the most changed from their original sedimentary condition. The 

higher Huronian group of gneisses, quartzites, conglomerates, dolomites, and argillites are at once the most thinly bedded and least metamorphosed. Individual beds remain as specialized as the day they 

were deposited. At the lower exposures of the whole Archean forma-
VAN HISK.J DISCUSSIONS OF PRINCIPLES. 449

tion well defined crystals are of great rarity; even microscopic apatite, 

the best presented species, is generally crushed and dislocated; micas 

are distortedj and all feldspars are more or less fragmentary. A 

marked contrast is observable at the upper extreme. Here many 

micas, hornblendes, garnets, and even feldspars are nearly, if not quite, 

completed crystals. The exceptions to this are those places already 

described, where local compression has broken up the original arrangement of the crystalline ingredients.

Nearly every considerable mountain body between the Wasatch and

the California line shows in the lowest horizons exposures of one or

/more bodies of granite. These are classified into four groups upon

I petrological grounds. The first type consists of quartz, orthoclase, an

} unimportant amount of plagioclase, and muscovite, with a small quan1 tity of microscopical apatite. These are all west of Eee&e« river, longiytude 117°. These are all associated with the Nevada type of Archean 

/crystalline schists composed of quartz, biotite, muscovite, and magnetite, or quartz, hornblende, and magnetite. As to the age of the granites of this type there are practically no data available. At one place it 

is intimately involved with the crystalline schists and is overlain uncon. 

formably by the Carboniferous;> There is little doubt that it is Archean 

but its reference to that period is on general lithological grounds. The 

second type is of the same composition as the first, except that biotite 

is substituted for muscovite. It has a range from the Ombe mountains 

west of Salt lake desert to the California line. The third type is like 

the second except that biotite and hornblende are found together. This 

distribution is coextensive with that of the second type. The fourth 

type is the most complex in its petrological features of any of the famjilies of granite, and consists of quartz, orthoclase, plagioclase, often 

/ equal in quantity to the orthoclase and sometimes exceeding it, usually 

a high percentage of biotite and hornblende, titanite, and a high proportion of microscopic apatite. Between this class and the diorites that 

are unusually rich in orthoclase there is but little difference, although 

there is little danger of ever confounding the granitoid diorite with the 

dioritic members of the fourth type. These granites are the most prominent as regards geographical distribution of the truly eruptive varieties observed in the Cordilleras. When the different types of granite 

are seen in apposition so as to give a clew as to their relative ages it is 

found that they occur in the order given. In denominating these groups 

of granite as eruptive it is only intended to indicate that in their relations to the contiguous Archean schists they have the appearance of 

intrusive bodies, and that in their interior structure and general mode 

of occurrence there are none of those evidences of alliances to the crystalline schists which are observed in the granitoid gneisses of so many 

localities, especially in the Eocky mountain region. In so-called eruptive granites there is neither parallelism of general bedding nor of interior arrangement of the minerals, and the most ordinary phenomenon 

Bull. 80 29
450 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

of structure is the development of conoidal shapes formed of concentric 

layers varying in thickness from a few inches to 100 feet. This structure, 

so far as observed, is strictly confined to the hornblende-bearing granites, and never makes its appearance in those of the first and second 

types. Although instances of each type of granitic rock are found unconformably underlying the low members of the Paleozoic series, this is 

not the case with each outcrop; many granitic masses are found unconformably underlying Mesozoic or even Tertiary volcanic rocks. But 

there is absolutely no evidence whatever in favor of the belief of 

granitic extrusions later than the Archean age. Although Whitney 

has found intrusions of granite in sedimentary strata other than the 

Archean crystalline schists, any attempt to correlate age by petrological features alone is dangerous, as may be shown by the fact that the 

Jurassic granite of California and the granite of the Cotton wood region 

on the Wasatch, which is unmistakably Archeau, are positively identical down to the minutest microscopical peculiarity.

In the crystalline schists and gneisses are found identically the same 

minerals which characterize the granites. In the schists the characteristic feature is the parallel bedded arrangement. Granite possesses 

the same minerals; the sole difference seems to be that granite is often 

demonstrably a .plastic intrusion and possesses no parallel arrangement 

of minerals. The geognostic position of the schists is exactly like the 

other strata which were deposited horizontally and afterwards disturbed. On the other hand, granite in an immense majority of cases 

is found exposed in the hearts of the mountain ranges. It is only 

when we can observe granite in direct connection with the strata into 

which it has intruded or out of which it has been made that the true 

relations can be seen; and it is safe to say that wherever these intimate relations are observable, the granite occupies a region which has

been subjected to horizontal or circumferential pressure. The frequent 

phenomena of the under-dip of the strata flanking a granite mass, as in 

the great granite body of the Sierra Nevada, are prominent instances 

of the intimate relation spoken of. If in such cases an uncoiiforinable 

overlying and unaltered series were, to cover all but the summits of 

the granite hills, the granite would appear simply as an unconformable underlying body whose genetic relations are absolutely unknown. 

Into this category a vast number of granite exposures of the Cordilleras 

have to be placed.

It is an invariable law, then, that where the genetic relations are 

clearly perceived, eruptive granite is always found in connection with 

very great horizontal pressure and consequent disturbance. Suppose^ 

now, a deep-lying series of varied sedimentary beds, covered by a sufficient superimposed mass to exert a pressure powerful enough to sink 

them to the necessary thermal horizon for the induction of crystallization in the material of the beds. As long as the attitude of these beds . was undisturbed by horizontal compression, the result would be a
VAN HUB.] DISCUSSIONS OF PRINCIPLES. 451

series of crystalline schists and gneisses. But the moment horizontal 

or tangential pressure either overcame or disturbed the action of the 

downward pressure, the horizontal arrangement of these crystallizing 

materials would be broken up? and their resulting arrangement would 

depend upon the interaction of the two forces.

SELWYN,11 in 1879, proposes the following general stratigraphy for 

the older rocks: I. Laurentian: To be confined to all those clearly lower 

unconformable granitoid or syenitic gneisses in which we never find 

interstratified bands of calcareous, argillaceous, arenaceous, and conglomeratic rocks. II. Huronian: To include (1) the typical or original 

Huronian of lake Superior and the conformably or unconformably, as 

the case may be overlying upper copper-bearing rocks j (2) the Hastings, Templeton, Buckingham, Grenville, and Eawdon crystalline limestone series; (3) the supposed Upper Laurentian or Norian; (4) the 

altered Quebec group and certain areas not yet defined between lake 

Matapedia and cape Maquereau, in Gaspe"; (5) the cape Breton, Nova 

Scotia, and New Brunswick pre-Primordial subcrystalline and gneissoid groups. III. Cambrian: In many of the areas, especially the 

western ones, the base of this is well defined by unconformity, but in 

the Eastern Townships and in some parts of ISTova Scotia it has yet to be 

determined. The limit between it and Lower Silurian is debatable 

ground. One point is particularly insisted on, that great local unconformities and lithological differences may exist without indicating any 

important difference in age, especially in regions of mixed volcanic and 

sedimentary strata, and that the fact of crystalline rocks (greenstones, 

diorites, dolerites, felsites, norites, etc.) appearing as stratified masses 

and passing into schistose rocks is no proof of their not being of eruptive or volcanic origin; their present inetamorphic or altered character is, 

as the name implies, a secondary phase of their existence, and is unconnected with their origin or original formation at the surface, but is 

due partly to original differences of composition and partly to the varying physical accidents to which they have since their formations 

respectively been subjected.

SELWYN, 12 in 1881, states that the anorthosite rocks are in general 

conformity with the crystalline limestones, but are occasionally interfered with and disturbed by intrusions (?) of the more massive and 

granitoid variety of labradorite. This is proof that the labradorite or 

ISTorian rocks of Hunt do not constitute an unconformable Upper Laurentian formation, but occur in part as unstratified intrusive masses, 

and in part as interstratifications with the orthoclase-gneisses, quartzites, and limestones of the Laurentian system, as developed in the 

Grenville region, and mapped by Logan.

As to the granites which have been regarded as intrusive by Logan, 

both in the crystalline and fossiliferous rock, there is no doubt they 

a.re of later origin than the Silurian, rocks which surround them, and 

which are everywhere, on approaching the granite, considerably al-
452 PRE-CAMBRIAN ROCKS OF NORTH AMERICA.

tcred; chiastolite, andalusite, garnet, niica, and other mijicrals appearing in the slates, which are also occasionally changed to quartzose or feldspathic mica-schists, and the associated fossiliferous limestone to crystalline and micaceous dolomites with the fossils still perfectly distinct. It has been customary and orthodox to regard these 

granites as " intrusive," and they are so designated by Logan. The 

author holds that there is absolutely no proof of their being so, either in 

the Eastern Townships, in Nova Scotia or in Australia, and that all the 

phenomena connected with them may be more readily explained and 

understood if we regard them as completely metamorphosed portions 

of the strata which now surround them; while the mere displacement 

of strata involved in the intrusive theory appears, in view of the enormous area now occupied by the granite, wholly inexplicable, as does 

also the manner in which the surrounding strata often dip down against 

and on to the granite and show no signs of having been deflected or 

otherwise affected as regards strike and dip by the supposed intrusions.

There is, however, often seen along the contact lines of the granite 

and the slates a considerable breaking up and crushing of tlje latter, 

and this has been held to indicate' and be the result of the intrusion 

of the granite. It appears to be mainly due to the unequal resistance 

that the two rock masses have offered to the disturbing forces of upheaval, depression, and consequent pressure which have repeatedly 

affected them long after the formation of the granite. The effect thus 

produced is analogous to that which occurs where the forces producing 

slaty cleavage encounter interstratifled hard layers of sandstone, when 

the elsewhere perfectly regular and parallel cleavage planes are immediately crushed, crumpled, and deflected.

In regions where the granite or other hard crystalline rock is older 

than the adjacent or alternating softer strata, perfectly similar contact 

lines may be Seen, but unaccompanied by any change in the mineralog 

ical character of the adjacent strata, such as occurs when the crystalline rock is the youngest; and therefore this phenomenon can not be 

taken as conclusive evidence of the intrusive origin of granite or other 

crystalline rock.

SBLWYN, 13 in 1883, remarks that the Devonian granite-forming epoch 

has had immense influence in the pre-Carboniferous rocks of the region to 

the southeast of the great St. Lawrence, Champlain, and Hudson river 

break. This is certainly deserving of more careful consideration and 

study than it has yet received, and more especially so in connection with 

the alteration and metamorphism it has produced in large areas of 

Paleozoic, and perhaps pre-Paleozoic rocks. When tbese altered Paleozoic strata come in contact, as they often do in eastern Canada and in 

New England, with the more ancient Huronian and Laurentian gneiss, 

granite, mica-schist and other crystalline rocks, it is only possible to 

distinguish them or to define their respective limits by the most careful 

and minute stratigraphical work, such as the nature of the regions in
VANHISE.] DISCUSSIONS OF PRINCIPLES. 453

New England and in the adjacent provinces of Canada, where these 

rocks are chiefly developed, renders almost impossible, or at any rate 

has never yet been attempted. Hence the maps hitherto published^ 

representing the geological structure of these regions, have necessarily 

been based almost entirely, so far as the crystalline groups are concerned, on lithologicaland mineralogical comparisons and considerations, 

producing petrological rather than geological maps, and as a consequence, though important and valuable aids to future investigation, 

they afford a very incorrect and imperfect idea of the true geological 

structure and the sequence and distribution of the several formations. 

Unfortunately, while careful, patient, and minute observation in the 

field has been unavoidably limited and local, study in the laboratory 

and theoretical deductions therefrom have been unlimited and widespread, but, as might have been expected, have not only afforded no 

satisfactory solution of the intricacies of Appalachian geological structure, but have on the contrary involved it in deeper mystery and complication. It is now evident that an entirely different system of 

procedure must be adopted before there will be any hope of definitely 

and satisfactorily solving the problems which have been presenting 

themselves to successive observers in this difficult field.

SELWYN,U in 1884, states that recent investigation has greatly enlarged the area over which the Archean rocks are known to extend, 

though it has not yet afforded any more satisfactory evidence of the relations of the Huronian rocks to the Laurentian. In all cases the supposed junction of the strata of the two systems either shows them vertically side by side or the Huronian strata apparently dipping under 

the Laurentian, while both present a very constant northeasterly strike. 

Notwithstanding these facts, their exceedingly different mineralogical 

characters and general appearance, broadly viewed, render it almost 

impossible to suppose that the superposition, as indicated by these dips, 

is the true one, or that the Huronian is not newer than the Laurentian. 

If so, then we must admit that both systems are presented in a constant 

succession of enormously thick overturned folds, with perhaps many 

dislocations and slips on the lines of the anticlinal axes.

As regards the so-called Norian or Upper Laurentian formation, the 

writer has no hesitation in asserting that it has, as such, no existence 

in Canada, its theoretical birthplace. Wherever these Norian rocks 

have been observed they are either intimately and conformably associated with the ordinary orthoclase or pyroxenic gneisses, or they occur 

as intrusive masses when they present no gneissic or bedded structure. 

They clearly cut the surrounding gneiss, and are probably due to volcanic or other igneous agency in the Laurentian age. Such masses 

may not unreasonably be supposed to mark the sites of the Laurentian 

volcanoes, while the bedded labradoritic gneisses and other associated 

strata may with equal probability represent the eruptive rocks ^lavaflows, etc. which emanated 'from them3 and were locally interbedded
454 PRE-CAMBRtAN ROCKS OF NORTH AMERICA. [BULL. 86.

with the ordinary sediments of the period, as rocks of similar origin 

and composition certainly were in the Huronian and in all later geological ages, a fact which has been singularly overlooked or ignored by 

most writers on American geology.

At present we have in Canada no evidence which would warrant us 

in making more than two great divisions in the Archean crystalline 

rocks. In many parts, especially in the eastern provinces, it has been 

found impossible to define even these clearly. Bocks of typical Laurentian character are there so intimately associated with others of equally 

typical Huronian characters, and in such constant alternations, that in 

mapping them they could not be separated, and are therefore all classed 

as Archean or pre-Cambrian.

WHITNET and WADSWOETH,IS in 1884, after a very wide but disproportionate review of the literature of the pre-Potsdam rocks, conclude 

that it is impossible for any unprejudiced worker in this department of 

science to peruse with care<the pages given and not be obliged to admit that the geology of a large portion of this country, and especially 

that of Canada and New England, is in an almost hopeless state of confusion. The belief is justified that our chances of having at some future 

time a clear understanding of the geological structure of northeastern 

North America would be decidedly improved if all that were written 

about it were at once struck out of existence. While not desiring to 

conceal the fact that some of the problems presented in the course of 

the study of the older rocks are extremely difficult, it is clearly proved 

that want of knowledge, want of experience, and a desire to produce 

sensational theories, have brought about this condition of confusion.

In reference to Azoic rocks, there are several classes to which this 

term may be applied. First, it may be applied to strata once fossiliferous in which the evidences of life have disappeared. Second, rocks 

may be Azoic even if laid down when life was existing on the globe, 

provided the local conditions were not favorable to its development at 

the particular locality under consideration. Third, rocks must necessarily be Azoic when formed or originating under such a condition as 

were incompatible with the existence of life. Such was the original 

crust of the earth and the volcanic eruptive rocks. Fourth, we may 

have rocks formed under such conditions as were not inimical to life, 

but yet Azoic, because life had not begun to exist on the globe at the 

time of their deposition. These, according to our view, would be the 

rocks properly designated by the term "Azoic," and the body of rocks 

having this character might properly be called the "Azoic System." 

And we think that, in view of what has here been set forth, no one 

will deny that it is important that, if there are such rocks, they should 

have a special designation, and that the term "Azoic" would be a 

proper one to apply to them.

This, however, is exactly what was done by Foster and Whitney in 

1850, when they gave the name of the "Azoic System " to a body of
VAN HISB.] . DISCUSSIONS OF PRINCIPLES. 455

strata, originally in part, at least of sedimentary origin, which did 

not show by their character that life could not have existed at the 

time of their deposition, but which proved, on examinaion, to be entirely destitute of fossils, and which, moreover, were found everywhere 

. to underlie unconformably other stratified formations which were recognized as containing the lowest known forms of organic life. It is 

denied that Eozoon, beds of limestone, the presence of graphite in 

crystalline limestone, or any other discovered material in the pre-Potsdam rocks, are sufficient evidence for the presence of life.

It is considered that we are fully justified in saying that the results 

of geological investigation during the last thirty-five years have given 

no encouragement to the idea that below the well known Primordial 

zone the Potsdam sandstone of American geologists there is another 

series of fossiliferous rocks.

If the Azoic rocks are really azoic, as is believed, then it follows, as 

a matter of course, that the series thus designated can only be separated into subsystems on purely lithological grounds; if they are fossiliferous, as held by the Canada survey, then it is equally clear that 

any subdivisions proposed for them should have a paleontological basis. 

It is denied that Aspidella and Arenicolites spiralis are of organic 

origin.

If we examine the often repeated statement that the Huronian unconformably reposes on the worn edges of the Laurentian, and contains 

the debris of the latter, it will be found that in the seven cases in which 

the rocks referred to these two formations were found in contact in the 

Canadian district, the Huronian, with but two exceptions, is said to 

be conformable with and to generally pass imperceptibly into the Laurentian. In one of the these two exceptions the rocks show mutually 

intrusive relations, and in the other the Huroniau abuts against and 

runs under the Laurentian.

In all cases in which pebbles and fragments .of the Laurentian have 

been found in the Huronian, they were seen occurring high up in the 

latter series, and not,forming basement conglomerates. All the other 

so-called proof of unconformity has been made out of the fact that the 

strike of the foliation in the two formations, when not in contact, has 

been found to be discordant worthless evidence unless the rocks observed in both formations be proved to be sedimentary and the foliation be shown to be coincident with the stratification. Now, if the 

Laurentian was an old metamorphosed sedimentary formation which 

had been upheaved and contorted, and on whose worn edges the Huronian has been laid down, the evidence of the fact ought to be overwhelming in amount after the country has been studied for so many 

years.

It is well known that any eruptive rock so soon as it comes in contact 

with erosive agencies will yield fragmental material even before it is 

cold, and that much eruptive matter is ejected in a fragmental state?
456 PRE-CAMBRIAN ROCKS OF NORTH AMERICA.

so that in a mixed series of eruptive and detrital rocks nothing is more 

common than to have the debris of one inclosed in another, without 

that inclosure proving that the rocks differ in geological age. This is 

well known to be the case with the copper-bearing rocks of Keweenaw 

point, and it has been shown that the iron ores of the Marquette district, which form a constituent part of the so-called Huronian, are overlain by a conglomerate containing the debris of the former j yet both 

are by every geologist placed in the same series.

The basis of fact which forms the main support of the twofold division of the Archean including under that designation all rocks lying 

below the lowest fossiliferous series is this: the axial or eruptive 

portions of disturbed and mountain regions are largely granitic and 

gneissoid in character. These granitic, granitoid, and gneissic masses 

are brought to light in the cores of great mountain chains, where longcontinued uplift of the original crust of the earth has through a succession of geological ages been furnishing the material from which the 

sedimentary formations were built up. That the gneissic or gneissoid 

rocks are closely allied to the distinctly granitic and not necessarily 

metamorphosed stratified deposits is clear, as the result of long continued investigations in regions where rocks of this kind occur. Not 

that all gneisses are of this character; but those are ordinarily so 

which with granite make up the axial masses of disturbed regions. 

That the parallel structure of the materials forming gneiss is not necessarily the result of sedimentation seems clearly to result from that 

which has been done both in experimental and field geology within 

the last few years. It can not be denied that a foliated arrangement 

or a. parallel disposition of the mineral elements of various sedimentary 

rocks can be, and often has been, induced in them after their deposition, 

and that this parallel arrangement is not by any means neecssarily 

Coincident with the planes of stratification. This fact alone is absolutely 

conclusive in favor of the idea that parallel arrangement of the mineral 

constituents of a rock in other words, a gneissic structure, in rocks 

of the granite family is not proof of sedimentation.

Overlying the granitic and gneissic axial rocks we are likely to find, 

and in many cases do find, the stratified .masses which were formed 

from the preexisting crust themselves usually highly metamorphosed, 

because formed at a period of great chemical and mechanical activity. 

With these stratified and highly altered masses are associated eruptive materials both interbedded and injected in dike form these also 

often greatly metamorphosed, and to such an extent that their original 

character is only with difficulty, and with the aid of the microscope, to 

be recognized. This protrusion or forcing out of eruptive materials 

seems to have followed the preceding uplift of the original crust, if not 

as a necessity at least as something extremely likely to occur, as is 

shown by the fact that in so many great mountain chains we find volcanic activity more and more predominating with the progress of
VAN HUE.] DISCUSSIONS OF PRINCIPLES. 45?

geological time. Since these eruptive materials come from a gradually 

increasing depth below the surface of the original crust they are more 

basic than this, and, since as a rule they contain more iron than that 

crust, are darker colored than the masses by which they are directly 

underlain. Hence the detrital beds formed from the debris of these 

more basic materials are themselves of a dark color, and as a result of 

their metamorphism we have the various slates, argillaceous, talcose, 

and chloritic, which so commonly rest upon the granitic and gneissoid 

rocks which form the core or axis of the disturbed region. With these 

slaty rocks are also associated limestone masses, which, so far as our 

observations go, are not ordinarily interstratified with the slates, but 

are of the nature of segregated deposits, having been formed posterior 

to the formation of the sedimentary beds with which they are associated, while the metamorphosing agencies were at work making over 

the beds into the crystalline form in which we now see them.

In the division of the rocks into Laurentian, Huronian, Korian, 

Montalban, Taconian, Arvonian, only lithological principles are now 

used, and every fact pertaining to the origin and relations of these 

rocks is ignored; and since, while it is assumed that all these rocks 

are sedimentary, they are found to occur in dikes and other eruptive 

forms, it becomes necessary to hold that all eruptive (including volcanic) rocks were the products of a rnetamorphic (aqueo-igneous) 

action. Hence it is claimed that all these rocks had been deeply 

buried and then denuded, and most extravagant views have become 

current regarding denudation.

It thus came about that the coarser grained granitoid and gneissic 

rocks were set apart as Laurentian; the gabbros and some of the more 

coarsely crystalline diabases and diorites were erected into the Norian; 

the felsites and quartz-porphyries were placed as the Arvonian; the 

finer grained diorites, diabases, melaphyres, and chlorite-schists were 

formed into the Huronian; the more friable granitic and gneissic rocks 

with the mica-schists were classed as Montalban, and the quartzites, 

limestones, and argillites were united into the Taconian. Of course, in 

each case the metamorphic fragmental forms of each rock were placed 

with the rocks they resembled, while the other forms of crystalline 

rocks were distributed through the groups.

ADAMS,16 in 1887, gives a general consideration of the Upper Laurentian or Norian, which has been separated from the Lower Laurentian 

by the predominance of plagioclase feldspar. These rocks occur in 

detached areas in the Laurentian districts and are similar to the gabbro and gabbro-diorites of Scandinavia. At least nine areas are known 

to exist in Canada, and one in the state of ISTew York. Besides pyroxene 

and plagioclase, many other minerals are found.

The rocks show much variation in structure. They are rarely quite 

massive, frequently well foliated, but usually consist of a rather 

coarsely crystalline groundmass through which are scattered irregular
458 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL.S&

strings and masses composed of iron ore, bisilicates, and mica, as wel 

as larger porphyritic crystals of plagioclase. Even when tolerably con 

stant in composition there is generally a great variation in size of grain 

coarse and fine layers alternating in rude bands or rounded masses 

In the case of some of the areas there can be but little doubt that tht 

anorthosite is eruptive; in others, however, it seems to be interstrati 

fled with the Laurentian gneiss, and in one of them to merge imperceptibly into it. The original relations of the rocks are, of course 

much obscured by the effects of subsequent heat and pressure. Tht 

evidence at present, however, seems to indicate that the anorthosite^ 

are the result of some kind of extravasation which in early times corrp 

sponded to what in modern times we call volcanic eruption.

DAWSON, (SiE WILLIAM)," in 1888, describes the Eozoic rocks of tti«E 

Atlantic coast and compares them with those of western Europe anc 

the interior of America. ' '

The Laurentian system consists in all parts of the world largely 

orthoclase-gneiss associated with crystalline schists, and locally quart* 

ites and limestone.

No one who has studied the typical districts of the Ottawa river can 

doubt for a moment that they are regularly bedded deposits, and that 

in the Middle Laurentian those conditions which in later periods have 

produced beds of limestone, sandstone, iron ore, and even of coal, were 

already in operation on a gigantic scale. At the same time it may be 

admitted that some areas of the lower gneiss may be cooled portions 

of an original igneous mass, and that many of the schistose rocks ma^ 

be really bedded igneous materials.

Laurentian rocks compose the nucleus of the island of Newfound 

land, 'occur in cape Breton, and in southern New Brunswick. >

In the typical area of lake Huron, as originally described by Logat, 

and Murray, the Huronian rests unconformably on the Lower ami 

Middle Laurentian, and presents a great contrast in point of mineral 

character to these formations. It is comparatively little disturbed 

and is clastic rather than crystalline in character. This point has been 

well insisted upon by Bonney and by Irving in recent papers. Further, 

its conglomerates contain pebbles of Laurentian rock in the same 

crystalline state in which these rocks are found at present. It consists 

chiefly of quartzites, conglomerates of different kinds, limestone, am] 

slates, sometimes chloritic, with iuterbedded diorite.

In Newfoundland the older slate series of Jukes is lithologically very 

like the Huronian, and this likeness is increased by the fact that red 

sandstones and conglomerates like the Keweenian of the West over 

lie these lower slates.

On the coast of southern New Brunswick are the Coldbrook anc 

Coastal series, essentially like those of Newfoundland. The Coasta' 

group may perhaps be of later age than the Huronian proper, although 

pre-Cambrian.
VANHISB.] DISCUSSIONS OF PRINCIPLES. . 459

As iii Newfoundland, the typical Huronian of New Brunswick is 

overlain by conglomerates, sandstones, and shales. The Huronian rocks 

of Huron, Newfoundland, and New Brunswick are also compared with 

the Pebidian of Wales. The Huronian marks a period of igneous disturbance and coarse mechanical deposition succeeding to the Laurentian foldings.

IKYING, I8 in 1888, after a detailed consideration of the principles applicable to the classification of the early Cambrian and pre-Cambrian 

formations, reaches the following general conclusions as to the use of 

lithological characters and structural breaks in correlation.

Lithological characters are properly used in classification:

(1) To place adjacent formations in different groups, on account of 

their lithological dissimilarities, when such dissimilarities are plainly

the result of great alteration in the lower one of the two formations 

and are not contradicted by structural evidence, or if used as confirmatory evidence only, when such dissimilarities are the result of original 

depositional conditions.

(2) To collect in a single group adjacent formations because of lithological similarities when such similarities are used as confirmatory evidence only.

(3) To correlate groups and formations of different parts of a single 

geological basin when such correlations are checked by stratigraphy, 

and particularly by observations made at numerous points between the 

successions correlated.

They are improperly used:

(1) To place adjacent formations in different groups, on account of 

lithological dissimilarities, wlien such dissimilarities are merely the result of differences in original depositional conditions, and when such 

evidence of distinction is not confirmed by or is contradicted by structural and paleontological evidence.

(2) To collect in a single group adjacent formations because of lithological similarities when such similarities are not confirmed by or are 

contradicted by other evidence.

(3) To establish general correlations between the clastic groups of 

different geological basins, except possibly Avhen the gneissic and true 

crystalline schist basement formation of one region is compared with 

the similar basement formation of-another.

(4) To establish and determine any world-wide subdivisions of the 

noneruptive basement crystallines, i. e., those which underlie the clastic groups here called Huronian at least until very much more definite 

evidence of the existence of such subdivisions be gathered than has 

hitherto been done.

The structural breaks called unconformities are properly used in 

classification 

(1) To mark the boundaries of the rock groups of a given region.

(2) To aid in establishing correlations between the formations of different parts of a single geological basin.
460 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL.

(3) To aid. in the establishment of correlations between the groups 

of regions distantly removed from one another; but caution is nee'dec 

in attempting such correlations in proportion as the distances betweei 

the regions compared grow greater. ,

They are improperly ignored 

(1) When the evidence they offer as to separateness is allowed to be 

overborne by anything but the most complete and weighty of paleon 

tological evidence.

As here used the terms system, group, and formation are the three 

orders of magnitude in stratigraphical subdivisions. Cenozoic, Meso 

zoic, and,Paleozoic are systems; Carboniferous, Devonian, etc., groups 

and the subordinate members of these groups are formations. {

Applying these principles, it is concluded that such series as tli( 

Keweenawan and Huronian are entitled to the rank of groups (1) be 

cause, notwithstanding they include a considerable content of volcanic 

crystallines, they are nevertheless in the main made up of genuine secll 

imentary strata, whose formation by the same processes which havk 

been at work in the accumulation of later sedimentaries is easily 

demonstrable; (2) because they have accumulated during the existence! 

of life on the globe, as hereafter maintained; (3) because of their great! 

volumes, which are not only comparable with, but very considerably 

exceed those of the ordinary rock groups; (4) because they are divisible 

into subordinate members which are in turn fully entitled to the ranl£ 

of formations; (5) because of their entire structural* separateness fronl 

the oldest of the groups above them, from each other and from tlie 

crystalline basement rocks below them; and, finally, (6) because o: 

their presumptively wide extent.

Conditions similar to those of the lake Superior region recur in the 

Grand Canyon of the Colorado and probably also in central Texas. li 

Newfoundland, again, we have unconformably placed beneath the Cairi-^ 

brian, here developed with an enormous thickness, two mutually diss; 

cordant series, the upper one of which is entitled on the principles\ 

advocated in this paper to full recognition as a clastic group, while the 

lower one is crystalline and gneissic. In numerous other regions similar conditions have been more or less distinctly made out; but the 

geological column, as it is now ordinarily presented, provides beneath the Cambrian for one great division only the Archean. By 

some authors this Archean is recognized as divisible into Huronian 

and Laurentian; but very 'few writers, even when they have recognized 

the independent existence of pre-Cambrian and post-Laurentian groups 

seem to have accorded to' such groups the taxonomical rank to which 

they are entitled. Certainly there has been no general recognition of 

these groups, such as would lead to the provision for them of a proper 

place in the general .geological column. ',

If it is agreed that all clastic formations which unconformably underlie the Cambrian are1 to be thrown out of the Cambrian group, it is nee-
] DISCUSSIONS OF PRINCIPLES. 461

to inquire whether the new groups are to be regarded as- Paleo- 

;oic. All may be regarded as Archean; Paleozoic may be carried 

[own to the break between the Keweenawan series and the Huronian; 

Vrchean may be restricted to the gneissic basic series; and, finally, 

lome entirely new term of equal rank with Paleozoic and Archean may 

>e introduced to cover the formations between the gneissic series and 

the Cambrian. The apparent relative extent of the time intervals befween these several groups and the indications presented by them of 

lie existence of life during their deposition lead to the conclusion that 

here should be introduced a system term equivalent to Paleozoic and 

V.rchean. In favor of restricting Archean to the gneissic basement 

Trane are the facts that this is essentially a crystalline schist series, 

ving rarely any traces of fragmental constitution, because it shows 

amount of disturbance prior to the deposition of the Huronian, which 

intirely outweighs that received by the Huronian, while the amount 

'i denudation of the pre-Huronian land surface, as compared with that 

followed the Huronian, was immensely greater; and because 

any believe that the exact conditions which gave rise to the preuronian basement formation has never been repeated in later geoagical times.

I There is no satisfactory evidence of the existence of life previous to 

che deposition of the Huronian. That it existed plentifully in the 

EEuronian is indicated by the high development of life at 'the beginning 

f the Cambrian and its consequent necessary existence for great periods 

>rior to that time; by the occasional discovery of obscure fossil remains; 

xy the abundant occurrence of shales and slates filled with organic 

natter; by extended ferruginous strata whose original accumulation 

n the form of carbonate was certainly dependent upon the existence of 

ofganic matter. That the carbon of the shales is matter of genuine 

>rganic origin is shown by residual traces of hydrocarbons and by the 

act that the carbonaceous substance in character and occurrence is 

3titirely similar to that contained in the carbonaceous shales of later 

formations. If the term Paleozoic is to be used to cover all formations 

accumulated after the beginning of the existence of life, it should extend downward over the groups in question; but such is not its ordinary use, and to extend it downward over the Keweenawan and Huronian strata and the intervals indicated by the unconformities between 

bhe groups already discovered, and over such groups as shall be discovered in the vast area of the earth's surface not yet geologically 

known, does not seem warranted. It is therefore desirable that a new 

term shall be introduced of equal classificatory value? indicating that 

;he great pre-Cambrian and post-Archean series are zoic in character 

.nd are equal to or greater in volume than the Paleozoic. For this place 

is suggested the term Agnotozoic, but some of the writer's colleagues 

prefer the more noncommittal term of Eparchean, signifying simply 

jthe position of these formations upon the Archean.
462 PEE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86. \

The following table shows alternative arrangement suggested by the 

above:

Systems. Groups.

) Devonian .. ..............................

( Keweenawan ............................

Systems.

1

HUNT,19 in 1888, summarizes the results of his work on the arrange- | 

ment, subdivision, and nomenclature of the pre-Cainbrian terranes, as \ 

follows:

(1) Laurentian. Under this name, proposed and adopted by the 1 

author in 1854, is comprised the old gneissic terrane found especially in i 

the Laurentide and Adirondack mountains, as well as in the great 

Atlantic chain and in the Eocky mountains of the center of North 

America. To this same series the author has also annexed the similar 

gneisses of Great Britain and Scandinavia, as well as the old or central 

gneiss of the Alps. From the time of our first studies in Canada, in 

1847, we had pointed out the existence, in this gneissic terrane, of two 

subdivisions, one lower, of granitoid gneiss which blends with the fundamental granite, to which succeeds with unconformable stratification t 

a series of gneisses also granitoid, frequently amphibolic, interspersed; 

with quartzites and crystalline limestones, with serpentine. These two ' 

subdivisions, which we may provisionally name Lower and Upper Laurentian, have been called respectively the Ottawa gneiss and the Grenville series. In order to avoid all error it is necessary to note that the! 

title of Upper Laurentian was for some time given by Logan to the terrane designated afterward as Labradorian and Norian. It is therefore 

through misunderstanding that some have wished to retain as a designation of the upper division of the Laurentian terrane the term Middle 

Laurentian.

(2) Norian. The terrane thus designated by the author in 1870 is in 

large part composed of those stratified rocks with an anorthic feldspar 

base, to which the name norite has been given. This terrane, however, 

includes intercalated beds of gneiss, quartzite, and crystalline limestone, all being rather similar to those of the Upper Laurentian terrane. 

These norites, which have' sometimes been designated by the name 

gabbro, must not be confounded with the very distinct gabbros of the 

Huronian terrane, nor with certain plutonic rocks, to which they bear 

mineralogic resemblances. The facies of the norites serves to distinguish them.

(3) Arvonian. This terrane is composed in large part of petrosiliceous
JjisHisK.] DISCUSSIONS OF PRINCIPLES. 463

rocks which pass into the state of quartziferous porphyry, with which, 

owever, certain amphibolic rocks are intercalated, as well as sericitic 

schists, quartzites, oxides of iron, and more rarely crystalline limestone. This terrane, indicated for the first time by Hicks, in 1878, in 

Wales, is regarded by Charles Hitchcock as forming in North America 

the lower part of the Hnronian terrane.

(4) Hnronian. This name was given by the author in 1855 to a terrane already recognized in North America, where it rests nnconformably either on Lanrentian gneisses or on Arvonian hornstones. It comprises, besides quartzose, epidotic, chloritic, and calcareous schists, 

also masses of serpentine and Iherzolite, as well as euphotides, which 

r/epresent in this terrane the norites of the Norian terraue, Avith which 

they are sometimes confounded under the common name of gabbro. 

( This terrane predominates in the Alps, where it forms the series of

1-cd stones (pietre verdi).

. (5) Montalban. The studies of voii Hauer, published in 1868, on the 

eastern Alps, and those of Gerlach on the western Alps, published the 

year following, agree in recognizing in these regions two gneissic ter-

.4-anes, that is to say, an old or central gneiss and a young or recent 

gneiss; the latter, which is very distinct from the old gneiss from, a 

petrographic point of view, being accompanied by micaceous and amphibolic schists. The studies of Gastaldi, published in 1871, and those

'of Neri, published in 1874, while confirming Hauer and Gerlach's repiults, have furnished more details on these terranes and their lithoJ.ogic characters. It is proper to remark here that a,ll these observers 

s^eem to be agreed in placing the horizon of the greenstones (Huronian)

/between the old gneiss (Laurentian) and the young gneiss.

Before he had knowledge of the first observations of these scientists, 

the author, in accordance with his own studies in North America, was

led to identical conclusions; and in 1870 he announced the existence of f '

/a series of young gneisses,.quite distinct from the old gneisses, and 

accompanied by crystalline limestones and by micaceous and ainphi-

^'bolic schists. To this terrane, in view of its great development in the

'White mountains of New Hampshire, he gave in 1871 the name of 

Montalban. This series, for the rest, appears identical with the young 

gneiss of the Alps, with gneisses and mica-schists called Hercynian in 

Bavaria, with the granulites with dichroite rocks, mica-schists, and 

Iherzolite of the Erzgebirge in Saxony, and similar rocks in the mountains of Scotland. This Montalban terrane in North America includes 

not only crystalline limestones, but beds of Iherzolite and serpentine, 

quite like the Huronian and the Laurentian. It is also in this series

.that are found most of the " filonian" or endogenous masses of pegmatite, often inclosing emerald, tourmaline, and tin, uranium, tantalum, 

and niobium ores.

Gastaldi, in a memoir published in 1874, declares that the greenstones, 

properly so called, lie between the old porphyroid and fundamental
464 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

gneiss and the recent more finely grained gneiss, more quartzose than 

the other, which he also designates as gneissic mica-schist or as very 

micaceous gneiss passing into mica-schist and often amphibolitic; the 

two gneissic series being according to him easy to distinguish. To 

these two divisions above the old gneiss Gastaldi added a third division still more recent. This division contains considerable thicknesses 

of beds designated by him under the titles of argillaceous schists, or, 

rather, lustrous, talcose, micaceous, and sericitic (silk-like) schists. Associated with these schists are also found quartzites, statuary and 

Cipolino marbles, with dolomite, karstenite, and sometimes amphibolic 

rocks and serpentines, the presence of which in this division, and even 

in the recent gneisses, as well as in the greenstones, properly so called, 

seemed to him to justify the name of " zone of greenstones," often given 

by Gastaldi to the whole of this triple group of crystalline schists which 

he recognized as being less old than the central gneiss.

(6) Taconian. This third division, to which Gastaldi gave no distinctive name, has, as is known, a very interesting history in Italian 

geology. A terrane having at the same time the same horizon and the 

same mineralogical characters is found greatly developed in North 

America, where it comprises quartzites (often schistose and sometimes 

flexible and elastic) and crystalline limestones, yielding statuary and 

Gipolino marbles. There are also found there deposits of magnetitic 

and of hematitic iron, as well as important beds of limonite, the latter 

being epigenic either from pyrites or from carbonate of iron, two species 

which by themselves form considerable masses. This terrane furthermore contains roofing slates, as well as lustrous and unctuous schists, 

ordinarily with damourite, sericite or pyrophyllite, but inclosing sometimes chlorite, steatite, and amphibolic rocks with serpentine and ophicalcite. There are also found among these schists, which are found at

diverse horizons in this terrane, beds visibly feldspathic, with others of 

ill defined nature, which are transformed into kaolin by aerial decomposition. These same schists also yield remarkable crystals of rutile, as 

well as tourmaline, disthene, staurolite, garnet, and pyroxene. This 

terrane, which for the rest appears diamond-bearing, was described 

in 1859 by Lieber under the name of itacolumitic group. Eaton, as 

far back as 1832, had placed the quartzites and limestones forming 

the lower members of the group in the primitive terrane j while the 

argillites, found toward the summit of the same group, were regarded 

as constituting the lower division of the transition terrane, covered, 

according to him, unconformably by the fossiliferous graywacke (first 

graywacke) which formed the upper division of the same transition terrane. Emmons, on his part, in 1842, comprised in what he called the 

Taconic system all this crystalline series, as well as the graywacke; 

but in 1844 he separated the latter, in which he had recognized the existence of a trilobitic fauna, giving it the name of Upper Taconic. Long 

studies have convinced the author that this upper division is entirely in-
VANHISE.J DISCUSSIONS OF PEINCIPLES. 465

dependent of the Lower Taconic, with which this fossiliferous gray wacke 

is in contact only in relatively restricted regions, Avhile in other localities it rests directly on older crystalline terranes. Seeing, moreover, 

that the Lower Taconic is found alone in a great number of localities 

from the gulf of St. Lawrence to Alabama on the south and to lake 

Superior on the west, and recognizing also the fact that the Upper Taconic really forms part of the Cambrian terrane (as for that matter was 

recognized by Emmons iii 1860), the author proposed as far back as 

1878 to restrict the employment of the term Taconic to this crystalline 

and infra-Cambrian series which forms the lower Taconic of Emmons

,' and the itacoluniitic group of Lieber, and to give it the name of Taconian terrane.

The mineralogical resemblances existing among the various crystalline terranes mentioned above are easy to recognize. The type of rocks 

with orthose base that appears in the fundamental granite and the 

Laurentian gneisses is also found in the quartziferous porphyries of the 

Arvonian and the gneiss of the Montalban, and less distinctly in the 

feldspathic rocks of the Taconian. The nonmagnesian micas, rare in 

the fundamental granite and the Laurentian gneisses, are found abundantly represented in the gneisses and mica-schists of the Montalban,

] as well as in the lustrous schists found in the Huronian and Taconian

/ terranes, and even predominate in the latter. It is still to be remarked 

that the simple silicates of alumina, such as andalusite, disthene, fibrolite, 

and pyrophyllite, which seem, foreign to the oldest terranes, abound in

' the Montalban and also appear in the Taconian. At the same time the 

crystalline limestones, the oxides of iron, and the calcareous and magnesian silicates are found represented in each terrane beginning

'' from the fundamental granite. The chemical and inineralogical differences between these various terranes are greater than the resemblances, 

which has not prevented certain observers from confounding the recent 

gneiss with the old gneiss. In fact, the resemblances between the 

Huronian and Taconian terranes have led the late Prof. Kerr, in North 

Carolina, to refer the latter terrane to the Hurouian terrane. In the 

vicinity of lakes Superior and Huron, too, where the Laurentian, Norian, 

Arvonian, Montalban, and Taconian terraues are found all at once, the 

outcrops of the latter have been confounded with those of the Huronian 

terrane by Murray and other observers. In 1873, however, the author, 

distinguishing between the two, gave to the Taconian terrane in this 

region the provisional name of Animikie series. Only later did he 

recognize the fact that this series, which in certain localities rests unconformably on the Huronian terrane, is only the Taconiau. Emmons, 

on the contrary, who knew the existence in this region of what he called 

the Lower Taconic, thought that the terraue to which in 1855 the author 

had given the name Huronian was identical with this same Lower 

Taconic or Taconian. The differences between the two terranes in the 

basin of lake Superior, indicated first by Logan and afterward by the 

Bull. 86 30
466 PEE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

author, appear very clearly from the recent studies of Eominger. On the 

various crystalline terranes, including the Taconian, there rests in this 

region unconformably an enormous series of sandstones and conglomerates, with contemporary plutonic rocks, the whole being remarkable 

for its content of metallic copper. This series, which had been alternately confounded with the Huronian and Taconian terranes on the one 

hand and with the trilobitic sandstones of the Cambrian on the other, 

was for the first time separated by the author in 1873 under the name 

of Keweenaw group, a term which he in 1876 converted into that of 

Keweenian terrane. It still remains to be determined whether this 

series, on which these same trilobitic sandstones rest unconformably, 

should form part of the Cambrian terrane or whether it should form a 

distinct terrane between the Taconian and the Cambrian.

BELL,20 in 1889. characterizes the Huronian as the great metalliferous series of Canada. While rocks of igneous origin constitute a 

marked feature in the Huronian system, a large proportion of it is made 

up of those of an undoubted sedimentary character. On the other 

hand, it is questionable if the great bulk of the Laurentian rocks can 

be proved to have been deposited from water. It is supposed by many 

that the foliation of much of the gneiss may have been produced by 

pressure and some kind of flowing movement iu an igneous mass.; 

Whatever view we may take of the origin of the common Laurentian 

gneiss, which, forms the surface of the country over such a vast extent 

of the Canadian half of North America, the commencement of the Huroiiian period marks a great change which then came over the earth 

a change characterized by widespread volcanic outbursts and by evidence of the existence of water (perhaps the first) on the surface of the 

globe, and of certain progress iu the building up of the aqueous de-' 

posits which has been going on ever since.

BELL,21 in 1890, gives a general account of the Archean. The Azoic 

or Archean period is divided into the Laurentian and Huronian systems, into which the primitive rocks of all countries may be classified, 

and which everywhere are essentially the same and retain the same 

relative positions. In some instances newer rocks have been so altered 

locally or over considerable tracts as to resemble the Azoic, but there 

is generally found some means of distinguishing between them. In 

Canada and the United States the Laurentian and Huronian are usually 

intimately associated, but their lithological features and internal characters are sufficiently distinct to separate them. The Huronian rocks 

are less contorted or corrugated on the small scale than the Laurentian, but on the large scale they partake of the same foldings which 

have affected the latter. The Huronian rocks seem to be interwoven 

with the Laurentian as basins or troughs more or less elongated, and 

as tracts of angular and other forms filling spaces between great nuclei 

or rounded areas of Laurentian rocks.

The Laurentiau system is divided into two formations, the lower of
VANHISB.] DISCUSSIONS OF PRINCIPLES. 467

which is sometimes called the primitive gneiss series. It consists essentially of obscurely foliated or stratiform granitic or syenitic gneiss. 

The prevailing colors of the Lower Laurentian gneiss are grayish and 

reddish. In some districts the Laurentian rocks are cut by dikes of 

greenstone or trap. In the Upper Laurentian are placed both the anorthosite rocks and the limestone-bearing series of eastern Ontario. The 

anorthosites, which are considered by some as eruptives and others as 

bedded rocks interlaminated with the limestones, may be in part of both 

origins. Anorthosites, after spreading out upon the surface of the earth 

or the bottom of the sea, may have become incorporated in a conformable 

^manner with the contemporaneous deposits, while others may have 

; fknved over preexisting rocks which were not disturbed. Between the 

; Upper and Lower Laurentian there may be a general want of conformity. 

The Upper Laurentian contains metallic ores and very numerous mins erals, which are not found in the Lower Laurentian. The gneisses of 

' the Upper and Lower Laurentian often have a close resemblance. As 

j the evidence is so strongly in favor of the aqueous origin, of a part of 

the Upper Laurentian at least, this lends support to the view that even 

the primitive gneisses may have been formed by the action of water 

during some early condition of the earth, of which we can form but 

.little conception judging by the later stages of its history. Eozoon is 

regarded as a myth, and the limestones, iron ores, graphite, and apatite are not considered as evidence of the existence of animals or plants 

in Laurentian times. The limestones may be chemical sediments; the 

graphite and apatite occur principally as vein matter; the iron ores 

occur in greater masses than in deposits of organic origin, and their 

mode of occurrence is opposed to any theory of this kind. The Upper 

Laurentian rocks seem to be much more limited in geographical extent 

than the Lower Laurentian.

The Huronian system in Canada has a great thickness and variety 

< of strata, for the most part crystalline, but in a less degree than the 

Laurentian, together with many unstratih'ed igneous masses. Like the 

Laurentian it is Azoic, or devoid of any trace of organic life, so that the 

distinction between the two systems is based entirely on lithological 

grounds. The difference in this respect is great, and is easily recognized 

by those who have paid any attention to geology. The prevailing dark 

green and gray colors of the Hurouian offer a marked contrast to the li ghter 

grays and reddish grays of the Laurentian. The latter are massive and 

coarsely crystalline, while the former are usually fine grained and schistose or fissile, this cleavage structure constituting a striking difference 

from the solid Laurentian. There are some exceptions to this rule, such 

as the light-colored quartzites and the granites and syenites of the 

Huronian, to be noticed further on. The change in passing from one to 

the other is often sudden and complete, but sometimes beds of passage 

are met with. The Huronian is the great metalliferous system of Canada. Although the Huronian strata have generally been thrown into
468 FEE-CAMBRIAN KOCKB OF NORTH AMERICA. IBULL. 86.

sharp folds, or stand at high angles, they are, as a rule, less bent about 

or contorted than the Laurentian. The total volume of the system is 

very great, probably not far from 40,000 or 50,000 feet, or perhaps even 

more.

In Canada, as far as our investigations have gone, the two systems 

appear to be everywhere conformable to each other, but in rocks of 

such ancient date and which have undergone such profound structural 

changes, owing to pressure, etc., affecting alike the stratified and 

unstratified portions, this appearance may not everywhere indicate a 

truly conformable sequence. Both sets of rocks having been thrown 

by lateral pressure into sharp folds, standing at high angles to the 

horizon, the Huronian often appears to dip under the older Laurentian, 

but this is merely the effect of overturning^ and does not show that a 

part of the Laurentian is newer than the locally underlying Huroniaii. 

Notwithstanding the geographical relations of the two sets of rocks, 

their general difference in character and composition would indicate 

that some great change in terrestrial conditions had occurred when the 

formation of the one system ended and that of the other began. In the 

Laurentian an "acid" or siliceous composition prevails, whereas the 

Huronian rocks as a whole are more basic, chemically speaking. The 

latter can be shown to be very largely of volcanic origin, although this 

may not always be obvious at first sight.

The term Huronian is made to include all the rocks lying between 

the Laurentian below it and the Cambrian or earliest fossiliferous rocks 

above. Among the areas placed with the Huronian are the Keewatin 

and similar rocks. In the Huronian are numerous areas of northern 

Canada, and perhaps certain of the rocks of Hastings and Lanark 

counties, some of the crystalline rocks of the Eastern Townships and 

the provinces of New Brunswick, Nova Scotia, cape Breton, and New- \ 

foundland. "In the Cambrian system are placed in ascending order 

the Animikie, Nipigon, and Potsdam formations. Between the Huro- N 

uian and Cambrian is a great unconformity. Between the Animikie \ 

and Nipigon and the Nipigoji and Potsdam are probable unconforini- ' 

ties.

WALCOTT,22 in 1890, gives a full account of the Lower Cambrian or 

Olenellus zone.

The base of the Olenellus zone is considered to be where the genus 

Olenellus, or the fauna usually accompanying it, first appears; beneath 

that horizon the strata are referred to some of the pre-Cambrian groups 

of rocks. In some cases the underlying rocks are in layers, conformably I 

beneath the Cambrian, and no physical separation of the two groups is ', 

possible. In other instances the subjacent rocks are the remains of the > 

old Archeau continent, near the shores of which much of the life of this 

portion of the Cambrian period existed.

The line of demarcation between the Cambrian and pre-Cambrian may 

be considered (1), at the base of the Olenellus zone, in continuous sec,- \
VANHISE.] DISCUSSIONS OF PRINCIPLES. 469

tions; (2) at the line of an nnconformable contact between any member 

of the Cambrian group and the subjacent Algonkian or Archean; (3) 

at the line of unconformable contact, which is the base of the Olenellus 

zone.

Placed in the Algonkian under this definition are 11,000 feet of 

quartzites, conformably below the Olenellus, in. the Wasatch; 10,000 

feet of argillites, sandstones, quartzites, and conglomerates, conformably beneath the Olenellus, in British Columbia; 12,000 feet of sandstones, shales, and limestones unconformably beneath the lowest known 

Cambrian, in the Grand canyon of Colorado; a similar series of rocks 

unconformably beneath the Cambrian in Llano county, Texas; a series

1 unconformably below the Upper Cambrian in the Adirondacks; and 

the rocks of St. Marys and Placentia bay, Newfoundland, which are 

unconformably below Lower Cambrian strata. In the Grand canyon,

> in a bed of dark argillaceous shale, 3,550 feet from, the summit of the 

section, was found a small Patelloid or Discinoid shell, a fragment of

, what appears to be the pleural lobe of a segment of a trilobite, and an

' obscure, small Hyolithes, in a layer of bituminous limestone. In layers 

of limestone, still lower in the section, an obscure Stromatoporoid form 

occurs in abundance. These fossils indicate a fauna, but do not tell 

what it is.

- The Olenellus fauna includes Spongise, Hydrozoa, Actinozoa, Eclii-

 noderinata, Annelida, P>rachiopoda, Lamellibranchiata, Gasteropoda, 

Pteropoda, Crustacea, and Trilobita. The abundance of the Olenellus 

fiiuna shows that the life in the pre-Olenellus seas was large and varied. 

The few traces known of it prove little of its character, but they prove 

that life existed in a period far preceding Lower Cambrian time, and 

they foster the hope that it is only a question of search and favorable 

conditions to discover it. 

DANA,23 in 1892, gives the following as the philosophical divisions of

( pre-Carnbriau times, although the early physical and biological conditions of the globe are not within the range of observation:

I. The Astral aeon, as it has been called, or that of liquidity.

II. The Azoic aeon, or that without life.

1. The Litliic era, commencing with completed consolidation; the time when lateral pressure for crust disturbance 

and mountain-making was initiated, and when metamorphic 

work began.

2. The Oceanic era, commencing with the ocean in its place; 

oceanic waves and currents and embryo rivers beginning 

their work about emerged and emerging lands, and the 

tides, the retarding of the earth's rotation. 

III. The Archaeozic seon, or that of the first life.

1. The era of the first Plants; the Algae and later the aquatic Fungi (Bacteria); commencing possibly with the mean 

surface temperature of the ocean about 180° F.
\

470 PRE-CAMBRIAN1 ROCKS OF NORTH AMERICA. [BUM,. 80.

2. The era of the first Animal life; the Proto/oaus, and 

forms related to the embryos of higher invertebrate species, 

commencing possibly with the mean surface temperature of 

the waters about 120° F., and ending with 90° F. or below. 

While these divisions mark off great steps in the progress of the developing earth, the rocks bear no marks of them that can be distinguished.

The Hurouian period covered probably much of Archeozoic time, 

and this is all in the way of correlation that can be said. It is well to 

note here that if the Eozoon. is really animal in origin, the "Laurentian" 

rocks of Canada in which it occurs must be Huronian or the later of 

Archaean terranes.

SECTION II. GENERAL DISCUSSION.

NAMES APPLIED TO PRE-CAMBRIAN ROCKS. '

In the early days of American geology the name Primary or Primitive was more widely applied to the ancient rocks than any other. 

Among the older geologists this name, including under it in a general 

way the pre-fossiliferous or metaiuorphic rocks, was used by Akerly, 

Alexander, Booth, Dewey, Ducatel, Baton, Enimons, Hitchcock (Edward), Jackson, Mather, Mitchell, Percival, Eogers (H. D.), Eogers (W. \ 

B.), Silliman, Tuomey, Vanuxeni, and others. It was nearly universal 

in 1820 and was applied as late as in the forties.

The term Primitive in the United States was gradually superseded 

by Azoic. Used by Adams as early as in 1840, in the literature of the 

fifties and sixties it very Aridely occurs, and has not yet disappeared. 

Among more prominent geologists in whose writings it may be found, 

are Adams, Cook, Crosby, Emmons (B.), Frazer, Hitchcock (C. H.), 

Hitchcock (E.), Kerr, Eogers, (H. D.), Safford, Whitney, Wadsworth, 

and others. In its earlier use Azoic was often made to cover all rocks 

which were apparently destitute of life, without reference to whether 

they are older than the fossiliferous rocks or not. It was thus applied by Adams, Emmons (E.) and the elder Hitchcock. With Eogers 

the Azoic included uoufossiliferous rocks which are younger than the 

Hypozoic or gneissic scries proper. Ordinarily, however, the term was 

used to cover all pre-Silurian sedimentary rocks, the Silurian being 

then regarded as the base of the fossiliferous systems. It was thus 

definitely defined by Foster and Whitney in their application of it to 

the lake Superior rocks and the Azoic was held by them to be strucurally indivisible. While the rocks of the Primitive and Azoic were 

early subdivided into lithological divisions there was little or no attempt to apply stratigraphical methods to them. Later the Azoic was 

subdivided by certain geologists into Laurentian, Huronian, etc.

The work of Logan and Murray marks in America the beginning of 

a truly structural study of the ancient rocks. They found in different
f VAKHISE.] DISCUSSIONS OF PRINCIPLES. 471

places in Canada pre-Carabraiu rocks which they mapped in detail. 

The two areas in which this work Avas begun were the north shore of 

lake Huron and the Laurentide mountains. With scientific spirit they 

applied to the rocks of these areas no terms which involved any theory 

of origin or equivalence, but gave the rocks the names of the localities, 

in this following one of the fundamental principles of good structural 

work. Having no fossils for guides, they built up a succession on the 

north shore of lake Huron by following formations in continuous exposure, by lithological likenesses of exposures separated by short intervals, by a like order of formations in different localities, and by the

, use of an unconformity, which was held to occur between the Huronian

/ sediments and the underlying crystalline rocks.

In Logan's work upon the Laurentian, the same methods were used 

as far as practicable, but on account of the complicated structure of the

i region his success was here much less conspicuous. The difficulty of the 

district drove Logan to take the one characteristic formation, the limestones as horizons to follow and to serve as planes of reference in working out the structure. But even this guide was not a certain one, as 

Logan never became quite sure as to the number of limestones present. 

As the study of the Laurentides continued the rocks were divided into 

two divisions, a Lower Laurentiaii free from limestone and an Upper

/ Laurentiaii containing the limestones. The two were held by Vennor,

^ and by Selwyn for a time, to be unconformable. As the area studied in 

the Laurentide mountains widened, anew formation was found, a laminated gabbro. It was recognized as being largely composed of labradorite or anorthite and so was first called Anorthosite or Labradorian, and 

afterwards Norian. The contacts of this formation with the other 

formations of the Laurentiaii were recognized as not those of cons formity.. In these early days it was naturally supposed that all laminated rocks, whatever their character, were sedimentary, and as in certain places the Labradorian appeared to cut across or overlap the old 

Laurentiaii it was designated as Upper Laurentiaii, and what had before been called Upper Laurentiaii was designated Middle Laurentian. 

When the eruptive character of the Labradorian was shown, the Canadian Survey returned to the first uses of the terms Upper Laurentian 

and Lower Laurentian.

In comparing the Huronian and Laureutian, it appears that the principle used in reaching the conclusion that the original Upper Laurentian, separated by a great distance from the original Huronian and nowhere in contact with it, is the older, was the nietamorphic character 

of the former as compared with the latter which in the early work of 

Logan and Murray was called a nonmetamorphic series. The lithological likeness of the gneisses and granites of the original Lower Laurentian to the granites and gneisses called Lower Laurentian unconformably underlying the Huronian doubtless was the reason for placing 

these as equivalents.
\

472 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 80.

In the later work of Logan and Murray the names Huroniau and 

Laurentian were applied to regions far distant from the original areas, the 

guiding principles for so doing being wholly lithological likeness and degree of rnetamorphisin. Workin g under these principles, as granites an d 

granite-gneisses are so abundant in the original Laurentian, and are 

nearly absent in the original Huronian, it became customary with these 

authors to refer to granitoid areas as Laurentian, while sedimentary 

series containing quartzites, limestones, or dark, fine grained schists 

were referred to the Huronian, and this reference was frequently made 

when the series as a whole was very much more crystalline than the 

original Huronian. The only exception to a reference of all pre-Cam- ' 

brian rocks to the Huronian and Laurentian were the series now known 

as Keweenawan and Animikie. These were recognized as resting 

unconformablyupon the so-called Huronian of lake Superior, while the 

Keweenawan was seen to be of a wholly different lithological character from the lake Huron rocks. These series were called the Upper 

Copper-Bearing series, the original Huronian often being called the 

Lower Copper-Bearing series.

We find these two geologists, Logan and Murray, starting with 

scientific principles, laboriously studying year-after year the detailed 

occurrences of the rocks in the midst of a forest-covered wilderness,, 

until their inductions built up the original Huronian and Laureutian 

series. In their later work of a very much less detailed character over 

vast areas the terms were applied somewhat indiscriminately, and in 

such a way as to imply that below the Upper Copper-Bearing rocks 

there are only two systems, one of which is equivalent to the original 

Huronian, and the other of which is equivalent to the original Laurentian.

These terms, Huronian and Laurentian, were gradually adopted by 

geologists working on the United States side of the boundary, so that 

in recent years, with the exception of Archean, they have been the 

most widely used of any names for designating the ancient rocks.

If Logan and Murray departed in their later work from strict scientific methods in their use, this departure was as nothing compared with 

the extremes to which later geologists of America have gone. By many 

geologists, coarse grained granites and granite-gneisses were designated 

as Laurentian without reference to evidence as to whether they were 

intrusive rocks of far later age. In applying the term Huronian the 

methods followed were even worse. Sometimes authors took a green 

color to be a characteristic feature of the Huronian and here referred 

all the green schists; others took a laminated structure to be characteristic of the series and here referred all the laminated rock, including 

even coarse grained laminated gneisses; others took the volcanics 

associated with the Huronian to be its characteristic feature and so 

called various pre-Cambrian volcanic series Huronian; others regarded 

metalliferous rocks as the important feature of the Huronian.
VANHISE.] DISCUSSIONS OF PRINCIPLES. 473

. Lying at the root of all this work is the assumption that rocks of a 

certain kind are characteristic of a definite period of the world's history, and that if rocks are found which are really like the Huronian 

and Laurentian in lithological character they should be referred respectively to these series.

As to the relations between the Laurentian and Huronian, it was 

plainly believed by Logan, Murray, and the other early geologists that 

where the two come in contact they are unconformable, although 

oftentimes the structural relations which obtain are admittedly obscure. That was the position of the present director of the Canadian 

survey as late as 1879, who used the term Huronian not only to include 

rocks that had been theretofore placed, but to cover all of the Upper 

Laurentian and the Upper Copper-Bearing series, thus greatly expanding the system. In recent years he has held that the Huronian and 

Laurentian are always conformable, and that often the former grades 

downward into the latter, and this is the position which has been 

taken by many geologists of the United States, both in the East and in 

the West.

The lake Superior region furnishes a rather marked exception, as do 

certain others, to the indiscriminate and unwarranted use of the term 

Huronian. This region is so near to and is connected in such a way 

with the original Huronian of lake Huron that it was possible to make 

a strong case of probability in favor of the equivalence of the clastic 

rocks of the two regions. The lake Superior Huronian was divided 

into formations upon the same principles used in mapping the original 

Huronian. While the term Laurentian was applied to the pre-Huronian rocks on the north shore of lake Huron and about lake Superior, 

it was recognized by a number of geologists that this was a variation 

from its application in the original Laurentian area.

As geological knowledge increased and as the theories involved in 

the terms Primitive and Azoic were more and more attacked, in order 

to avoid a theory of origin, the term Archean was proposed for the ancient rocks by Dana in 1872. This term rapidly grew in favor. By its 

use not only the advantage of a theory of origin was avoided, but in 

common with Primitive and Azoic it was not necessary to subdivide the 

ancient rocks into Laurentian and Huronian, and thus imply a correlation with the rocks of other regions. In the early rapid work of the 

Far West, detailed observations usually stopped at the base of the fossiliferous series, and it was convenient to regard all the remaining 

rocks as a unit, and to cover this unit the term Archean was adopted. 

After a more detailed study of certain regions the terms Laurentian and 

Huronian were applied to subdivisions of the Archean. This term 

Archean also found early favor with the Canadian survey to include 

these two divisions of pre-Carnbrian rocks.

Epzoic was another term suggested to replace Azoic, when it was 

thought by many that the rocks once supposed to be destitute of life
474 PRE-CAMBRTAN ROCKS OF NORTH AMERICA. [BULL. 8fi.

are not really so. This was used to a considerable extent in the sixties 

and seventies, and retains a place in literature to the present time. 

This term implies a theory just the opposite of Azoic.

As already said, the theory involved in* referring all pre-Cambrian 

rocks to the Laurentian and Huronian is that there was in pre-Cambrian time an invariable succession. This theory was carried to the 

extreme by Hunt and his school, who held that before Cambrian time 

there are six rock systems, which are universal and are separated by 

unconformities. These are, from the base upward: Laurentian, Norian, 

Arvonian, Huron ian, Montalban, Taconian. Of these terms Norian was 

devised to include the laminated gabbros, the so-called Upper Laurentian of Logan. Arvonian was imported from Wales, where it was applied by Hicks to a series of acid volcauics. Montalban came from the 

White mountain region in New Hampshire, where a series of gneisses 

was thought to be of different lithological character from the Laurentian and Huronian and to overlie them. Taconian was introduced by 

Ebenezer Emmons to cover a series of fossiliferous rocks which Avas 

supposed to be earlier than the base of the Silurian.

Besides the terms given, others have been used to some extent, but 

they are of little importance. Among these may be mentioned Hypozoic, Prozoic, and Pyrocrystalline.

As the metainorphic theory gained force it became the habit of many 

geologists to referto old crystalline or seniicrystalline rocks as metainorphic, assuming that they are all produced by the alteration of sediments 

of some kind. This went so far as to include perfectly massive rocks, 

such as diabases, gabbros, granites, etc., among the metainorphics. 

Becently the term has also been applied to rocks recognized as laminated eruptives, but this is not the use referred to. This term metainorphic had the advantage of saying nothing as to age or correlation, 

but in escaping this difficulty another theory was accepted which, SO 

far as its assumption is concerned, was quite as bad.

In many cases local names have been applied to formations or series 

in order to avoid any theory of age or correlation. The most conspicuous example of this kind is that of the Keweenaw series of lake Superior. 

More recently Lawson has proposed the terms Keewatin and Coutchiching for certain series northwest of lake Superior, and to include these 

two he proposes the Outarian system. In the Grand canyon the local 

names Chuar, Grand canyon, and Vishnu have been applied to preCambrian series which there occur. Comstock has proposed the terms 

Burnetian, Femandian, and Texian for series which are found in Texas.

This tendency to return to the use of local names in recent years is 

plainly a reversion to scientific methods which were never departed 

from by certain geologists. This class has declined to use any term for 

the ancient rocks which involves a theory of origin or succession, but 

have divided the rocks which they found in their respective districts 

into lithological divisions or into local formations. Conspicuous among 

early geologists of this class are Jukes, Percival, and Lieber.
VANHISE.] DISCUSSIONS OF PRINCIPLES. 475

Eocently Irving lias proposed that there be placed below the Paleozoic group another group of coordinate value, for which the term Agnotozoic or Eparchean is suggested. This term cuts out of the Archean 

a large class of rocks which have before been here included. Finally, 

the name Algonkian. has been brought forward by the United States 

Geological Survey for a systematic place opposite Agnotozoic or Eparcheaii.

In the following discussion, as stated in the introduction, Cambrian 

is denned as extending downward to the base of the Olenellus fauna. 

The pre-Olenellus elastics and their equivalent crystallines are called 

Algonkian, and the completely crystalline rocks below the Algonkian 

are denominated Archean. The reasons for these usages will appear 

in the following pages. The stratigraphical terms, group, system, and 

series correspond with the usage proposed by the International Geological Congress. The same is true of the chronological divisions, era 

and period. Formation is a lithological subdivision of a series.

THK CHARACTER OF THE ARCHEAN.

From the review of the literature it is plain that there is an essential 

unity in the character of the complex of rocks which is the oldest known 

in America. This statement covers all the areas in which the rocks 

are demonstrated to be exceedingly ancient. It includes the basal 

complex of Arizona, between which and the Tonto sandstone is a clastic 

system 15,000 feet thick, separated into three series by unconformities, 

and these again separate?!, from the Tonto above and the basal complex 

below by great unconformities;.it includes the basal complex of the 

Wasatch and certain of the ranges of Nevada, between which and the 

Olenellus Cambrian is a great unconformity and a thick series of quartzites; it includes the basal complex of southwestern Montana, between 

which and the Olenellus Cambrian is 12,000 feet of unaltered slates and 

a thick series of crystalline rocks of clastic origin, the two being probably separated by a great unconformity; it includes the basal complex 

of Texas, between which and the Cambrian is an unconformity, at least 

one and perhaps two thick series of clastic rocks; it includes the basal 

complex of the lake Superior region, between which and the Cambrian is 

an enormous system of elastics many thousands of feet thick, separated 

by unconformities into three series, and the whole bounded above and 

below by unconformities; it includes the basal complex of the north 

shore of lake Huron, between which and the Cambrian is a clastic series 

18,000 feet thick, bounded above and below by unconformities; it includes the basal complex of the original Laurentian area, between which 

and the Cambrian is a clastic series estimated to be many thousands of 

feet thick; it includes the basal complex of Hudson bay, between which 

and the Cambrian are almost certainly two, and perhaps three series 

of elastics separated by unconformities; it probably includes the basal 

complex of Newfoundland, between which and the Olenellus Cambrian
476 PEE-CAMBEIAN ROCKS OF NORTH AMERICA.

is a series of elastics 12,000 feet thick, and above this a great unconformity; it includes much of the great area of northern Canada known 

as Laurentian, between which and the Cambrian in various districts are 

clastic series.

In all of these regions in which the basal complex is vastly older 

than the Cambrian, it consists of a most intricate mixture of nearly 

massive rocks, among which granite and granite-gneiss are predominant; 

of gneissic and schistose rocks, all of which are completely crystalline, 

and so folded and contorted that nowhere has any certain structure 

ever been made out over considerable areas. The granites and basic 

eruptives may occupy considerable areas; the gneisses maybe regularly laminated and grade into the granites; the crystalline schists may 

occupy the outer zones of an area; they may all be confusedly intermingled, schists, gneisses, and granites alternately predominating; 

sometimes the schistose rocks appear in dike-like forms in the granites; 

at other times the massives are in dike-like forms in the schists; at 

still other times the alternations of granite, gneiss, and schists are 

quite uniform and persistent for considerable areas. The granites 

usually show a rough lamination, which may not appear in hand specimens, but which is evident in large masses.

The minerals in the rocks generally show evidence of dynamic action; 

they do not have the clear cut, definite relations characteristic of the 

later plutonic rocks. In the chief mineral constituents of the rocks 

there is essential uniformity in all of the areas, although certain less 

common minerals may be found in one area which have not been 

discovered in another. Orthoclase 'and acid plagioclase feldspar, 

quartz, hornblende, muscovite, and biotite are the standard minerals. 

To describe accurately the appearance of the rocks of the basal complex is exceedingly difficult, but any one who examines a series of 

specimens from the various areas will perceive the truth of the statement made as to the essential likeness of the rocks from different 

regions. A suite from any one of the regions which has been personally examined by me, if uulabeled, could by no possibility be asserted 

not to come from any other.

The unparalleled intricacy of the structure of this complex, the general laminated arrangement of its parts, and the broken and distorted 

forms of the constituent minerals are evidence of repeated dynamic 

movements of the most powerful character. Further, the basal complex is not only recognized by its positive but by its negative characters. Nowhere in it is a persistent thick formation of quartz-schist 

(although vein-quartz is abundant), of limestone or marble, of a graphitic schist, or of a conglomerate. If sandstones and limestones or other 

sedimentary materials have been a part of this system the profound 

and varied mutations through vast lapses of time have wholly obliterated all evidence of their presence.

Besides the areas mentioned in which these most ancient rocks occur,
VAN HIKE.] DISCUSSIONS OF PRINCIPLES. 477

there are many other areas in which there are between the Cambrian 

and the basal complex great series of clastic rocks, although the evidence at hand in favor of vast age for the basement complex is less than 

in cases before cited. Here are included the Front range of Colorado, 

which has between the basal complex and the fossiliferous rocks on its 

eastern slope the clastic series of Boulder, Coal, and Thompson creeks; 

and the Quartzite mountains of Colorado, where between the basal complex and the Carboniferous is a great series of quartzites. There is 

definite structural evidence for placing these and other areas with the 

group first considered. In a third class of areas no definite evidence in 

the nature of intervening series shows that between the Cambrian and 

the basal complex has intervened an era or even a period.

Because of the unique lithological character of this fundamental complex in all these regions, and because of the essential likeness in structure prevailing, we have ground for grouping these rocks together, 

whether exactly of the same age or not. Lithological arguments for 

correlation may be well distrusted; but the exceedingly strange, varied, 

and complex lithological and structural characters of this system, the 

like of which we have no evidence has been duplicated anywhere in later 

times, is an argument of great weight. In the complexity of its parts 

and the implications of its structure it gives evidence of vast antiquity.

In Algonkian, Cambrian, Silurian, Devonian, and even later times, 

completely crystalline schists have been produced over large areas; 

but, while often in these systems no evidence now remains of clastic 

characters, they rarely if ever closely resemble this fundamental complex. A clastic series was in the beginning of its history of necessity 

a shale, a sandstone, a limestone, a chert, or some other form of sediment and often containing carbonaceous material. Cementation, metasomatism, dynamic action may have profoundly changed any of these 

deposits. A limestone may have been transformed into a crystalline 

marble, or if impure into a hornblende schist containing scarcely a remnant of original carbonate. A cherty carbonate of iron may have become 

an actinolite-magnetite-schist. Carbonaceous shaly material may have 

become a graphite-schist, but if such a rock is represented in the fundamental complex what has become of the carbon? A sandstone may 

have become a granular quartzite or a foliated micaceous quartz-schist. 

But that a great quartzite formation like those of the Huronian of lake 

Superior or the pre-Olenellus of the Wasatch can have become wholly 

obliterated by any process short of fusion is almost inconceivable. As 

has been said, none of these rocks are found in this fundamental 

complex throughout its whole vast area. In its positive as well as 

its negative qualities it is a unit. While it can not be considered 

demonstrated that all of its area are of the same age, it may then be 

accepted that in North America is a system of granites, gneisses, and 

crystalline schists which are the oldest rocks of North America, and 

which have representatives in many areas throughout the United States,
478 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

although, most widespread and abundant in Canada. That such a basal 

system exists is no new idea; but it has not generally been recognized 

that between it and the Cambrian there elapsed an era in which were 

alternating cycles of the deposition of systems of rocks and of vast erosion intervals.

As here used the term Archean is restricted to this fundamental complex. It is no longer possible to regard as a unit or treat together all 

the pre-Cambrian rocks. The rocks included in the fundamental complex are everywhere called Azoic or Archean. The crystallines and 

semicrystallines above this complex, often called Archean, must be distributed from the Devonian or later to the pre-Cambrian. It is clear 

that if Archean is to remain a serviceable term it must be restricted to 

some unit. Such a unit is the fundamental complex, and to it this term 

is most appropriate.

ORIGIN OF THE ARCHEAN.

As has been shown, whatever the origin of the Archean, it is of vast 

age. It will be remembered that south of the lake Superior region, 

where is known the greatest volume of pre-Cambrian elastics, there is 

abundant evidence showing that the lowest of the clastic series has 

derived its d6bris from and rests upon the foliated edges of the Archean. 

In the Arizona region, in which the time of the pre-Cainbrian elastics 

is only inferior to that of the lake Superior region, the evidence of a 

great hiatus below these elastics is of the most decisive character. 

The same may be said of several of the other areas of Archean. Consequently in many regions the Archean complex, in essentially its present 

condition, maybe asserted upon definite structural evidence, to be vastly 

older than the Cambrian.

As to the origin of the Archean rocks, three different views are 

prominent: (1) The Archean has been considered as metamorphosed 

detrital rocks; (2) it has been considered as igneous, but later in origin 

than certain of the pre-Cambrian elastics with which it is in contact; 

(3) it has been considered as igneous and representing a part of the 

original crust of the earth, and therefore earlier than any sediinentaries. 

A modification of this theory is suggested under the topic Delimitation 

of the Archeau.

(1) Those who believe in the detrital origin of the Archean, as above 

defined, will not question the conclusion reached as to the age of the 

fundamental complex; for to produce results so different from any 

known metaiu.orph.ic clastic series must not only imply great age, but 

probably sediments which were originally deposited under different conditions from those of later times. This school, while believing in the 

detrital origin of the Archean as a whole, is conscious that it has 

been cut again and again by eruptives of all kinds; that the supposed 

elastics have thereby been profoundly metamorphosed by contact and 

dynamic action, and often have been so changed that the place can not 

be pointed out where the intrusives end and the elastics begin.
VANHISE.] DISCUSSIONS OF PRINCIPLES. 479

If this sedimentary view of the origin of the Archean be correct, as no 

universal break in geological continuity can be accepted, it should be 

found that between the Archean and the elastics there are somewhere 

gradations. It has been seen in the summary of the literature that 

Hitchcock, Marvine, Stevenson, King, Winch ell, and others, accepting 

such a sedimentary origin, believe gradations have been found in the 

Rocky mountain system, in the lake Superior region, and in the Appalachians, between the basal complex and the recognizable elastics. 

These authors have regarded the fact that as a whole these rocks show 

lamination as evidence that they Avere originally sedimentary. A few 

years ago it was a matter of course that distinct lamination in. a rock, 

however faint, is evidence of sedimentation. Lamination being found 

in the granite-gneisses, combined with the fact that these rocks graded 

into the elastics, was taken as conclusive evidence of the original sedimentary origin of the whole.

It is now everywhere recognized, as early shown by E. Eminons and 

Lieber, that schistose structure is often produced in eruptive rocks 5 

also like structures are produced in sedimentary rocks which have no 

relation to the original lamination, as early noted by Tyson, E. Einmons, Blake, Adams, E. Hitchcock, Jackson, Jnkes, .Rogers, and 

Lieber. E. Hitchcock, E. Eminons, and Lieber traced the actual gradations between schist-conglomerates and crystalline schists, while Mather 

traced the blue fossiliferous limestones into completely crystalline granular marbles. Laminated or schistose structure in crystalline schists 

then bears neither for not against a clastic origin.

The manner in which the finely laminated schists and gneisses vary 

into the coarsely granitoid phases has been admirably described by 

Jukes in the rocks of Newfoundland, by Lieber and E. Eminons in the 

rocks of the southern Appalachians, by Hitchcock in the rocks of 

Massachusetts and Vermont, by Marviue and Stevenson in the rocks 

of Colorado, by King, Hague, and S. F. Einmons in the rocks of the 

fortieth parallel, and by Lawson in the rocks about lake Superior. 

Most of these writers and many others, including Selwyn, approaching the problem from the side of the clastic rocks, have regarded the 

coarsely crystallized rocks as produced by metamorphism, although 

in the more granular rocks the process has gone so far as to produce 

aqueo-igneous fusion. Those who have maintained this origin for 

these rocks have recognized the fact that they have locally acted as 

eruptives, although in general the material is thought not to have moved 

far. Marvine so clearly saw that the facts could be explained in two 

ways that he says that, while he regards the whole as metamorphosed 

sedimentary rocks, another observer approaching the field from a different direction, where the evidences of intrusive nature are most manifest, would reach the conclusion that the whole is eruptive. Hitchcock 

and Stevenfiou and most of the others are in practically the same position.
480 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

The school of geologists that regards massive rocks as nietainorphic 

without any intervening time of fluidity, the granitic and gneissic layers interlaminated with the schistose being selectively metamorphosed, 

and the fragments of schist and gneiss within the massive rocks as 

residual unmetainprphosed material, while nearly gone, still has representatives. That the matrix of a fraginental rock could become slowly 

heated to such a temperature or be subject to such other conditions as 

are necessary in order that it should crystallize as a coarsely granular 

granitoid gneiss or granite, and not at the same time destroy the 

bowlders and pebbles which it contains, seems incredible. The explanation of these rocks and of the interlainiuations of granite with slate 

and schist by metamorpMsm implies not only that the fragments and ; 

the bands of slate and schist have been able to resist the forces of ' 

change during the slow processes which have been sufficient to produce 

coarsely crystalline material adjacent, but that in situ they have con- i 

tinned to resist these forces during all the time required by the matrices J 

to pass once more into ordinary conditions, The processes embodied \ 

in such " selective metamorphism " certainly need explanation.

The need of an exact definition of metamorphism is evident. It 

appears to the writer that it should not be applied to a rock which has 

actually suffered igneous fusion. Shall it apply to sedimentary material which has been free to recrystallize under aqueo-igneous fusion?; 

May not rocks under pressure beyond the crushing strength of rocks < 

and saturated with hot water recrystallize at a much lower temperature 

than is required for ordinary fusion 1? If so, where is the boundary ^ 

between aqueo-igneous and ordinary fusion? Is there not a transition 

between the two and does not aqueo-igneous fusion pass by imperceptible steps into ordinary metamorphism 1 Is there not here a transition 

between the extremes just as there is between different rock species, between basic and acidic rocks, between organic and inorganic sediments., 

between fragmental and crystalline rocks, between aqueous and surface igneous rocks.

(2) All or a part of the Archean is considered as of igneous origin, 

but later in age than the pre-Cambriau elastics. The facts of those who 

have described downward gradations from unmistakable elastics into 

a crystalline complex by this school have not been interpreted as 

above. It has declined to apply the term metamorphism to a product 

which has become fluent, and has insisted upon its essentially igneous 

character. Lawson is conspicuous as having recently strongly put this 

side of the case; but it is noteworthy that Winchell, belonging to the 

first school, and Lawson, to the second, have had essentially the same 

facts before them, both having done their work in the same region. The 

difference is one of definition and emphasis rather than ideas. Both 

"schools regard the granite-gneiss as material which has resulted from 

a change in the condition of original sediments and has not moved far.

This theory that the Archean or a part of it is the liquefied floor of
VAN max.] DISCUSSIONS OF PEINCIPLES. 481

the clastic rocks has the objection that it is an unverified hypothesis. 

When once a sedimentary rock has become fluent and is wholly free to 

crystallize anew how shall the material be identified? To state that 

such material has not moved far is pure assumption. If the fusion 

theory is true the average composition of the un fused part of the clastic series and the subjacent material should agree. To obtain average 

analyses of rocks which vary widely in mineral character within short 

distances is not easy, but is a thing which must apparently be attempted 

if this theory is to be maintained, for the writer sees no other way in 

which an attempt can be made to verify the hypothesis.

Another class of geologists, noting these contact relations between 

the granitic rocks and the elastics, hold that the former, called by others 

i Lower Laurentian or Archean, are eruptives of later age than the 

elastics with which they are in contact, without attempting to give any 

/ theory as to the source of the material. Here are included Hawes, 

[^ Hall, Mather, Foster, Whitney, Wadsworth, Rominger, Herrick, and 

^ others. Eomiuger distinctly recognized the granites and granitegneisses of this kind on the south shore of lake Superior as the subjacent 

rocks upon which the schists rest. Herrick saw the same relations with 

reference to his granitic and schistose groups on the north shore. In the 

last two cases the facts before the writers are precisely the same as those 

/of the geologists of the second school; but, by giving no explanation of 

I the source of the material for the granite-gneisses, they have escaped 

the difficulty of the unverified assumption that these eruptives reprei sent fijsed sediments. They fail to explain what has become of the 

floor upon which the elastics are deposited. Some floor they inuu; have 

had. Where these eruptive, contacts are found the floor has disappeared, and if so the eruptives, if extraneous, must be considered to 

/ have eaten up or absorbed it.

The three positions, that the granite-gneiss is selectively metamorphosed material, is due to subcrustal fusion, or is an extraneous intrusive, may be considered to grade into each other. Those who insist on 

the first have selective nietaniorphisin and contact phenomena to ex"- 

plain. Those who insist on subcrustal fusion may be called upon to 

identify their material. They can only show the former fused condition by contact phenomena, and contact phenomena are not evidence 

of progressive fusion, but intrusion. Those who regard the granitegneiss as intrusives may be asked what has become of the floor upon 

which the elastics were deposited.

(3) That the Archean is an igneous system earlier than any of the sediinentaries is apparently the conclusion of Einmons, Lieber, and others. 

These careful observers not only maintained the igneous origin of the 

granite-gneiss of the southern Appalachians, but traced the gradations 

between basic schistose rocks and massive eruptives, including hornblende-schist and unmistakable dikes, and drew the correct conclusion, 

lately regarded as a new discovery, that such rocks are sometimes 

Bull. 80 31
482 PEE'CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

metamorphosed eruptives. While the major portion of granite-gneiss 

and associated rocks were considered older than the oldest elastics, later 

intrusives of a similar character were recognized. This theory that 

the fundamental complex is igneous is that of Geikie as to the major 

part of the Archean of Great Britain and that of many German geologists as to the basal complex of Germany, among whom Lehmann and 

Koth are conspicuous. Indeed, thesel ast two maintain the igneous origin 

of all the pre-Oambrian rocks, and Geikie says of the true Archean of 

Great Britain that with certain possible exceptions it not only contains 

no material which gives any evidence of ever having been sedimentary 

material of any kind, but it further contains no material which can be 

considered a surface volcanic, while in it there are many rocks which ] 

are certainly plutonic eruptives. >

The geologists of this third school, with the second school, recognize 

the igneous character of the granite-gneisses having irruptive contacts \ 

with the clastic series, but they decline to recognize these rocks as,) 

Archean. Such rocks are eruptives. Their age is to be designated^ 

precisely as are eruptive rocks which cut Cambrian, Silurian, or De- ' 

vonian strata.

As bearing in favor of the really igneous character of the Archean is 

the fact that no case has been demonstrated, except possibly that of 

the marbles, of the production of a perfectly massive crystalline rock 

from a clastic without intervening fluidity. Metamorphism, whether \ 

the original rock is a massive eruptive or a stratified sedimentary, produces a laminated or schistose rock. If a granitic structure can be ] 

taken as evidence of eruptive origin, and we know many eruptive rocks 

do have such a texture, a very strong case can be made for the eruptive origin of the larger part of the fundamental complex. The line 

of argument is precisely analogous to that by which the whole has been, 

held to be sedimentary. There are complete gradations from the most 

completely schistose and laminated phases to the most massive phase. 

Also bearing in favor of a truly igneous character for the basal complex is the fact that the rocks referred in the first part of this section 

to the Archean are more nearly simulated by igneous rocks which have 

irruptive contacts with ancient elastics than by any recognizable metamorphosed sedimeiitaries. In this connection may be mentioned the 

occurrences in the Appalachians and in British Columbia of relations 

between granitic rocks and strata as late as the Carboniferous or Triassic, analogous to those which often prevail between the granite and 

granite-gneiss and the pre-Cambrian crystalline schists. Here the one 

class of rock is known to be sedimentary, the other intrusive. It may 

be said that the actual gradations between the Algonkian and Archean 

in certain places are evidence that the latter are not igneous rocks earlier 

than the former; that gradations can be explained between subsequent 

intrusives and elastics, but not between igneous rocks and sedimentaries 

of later age. It has, however, been shown that as a consequence of
VAWHIBK.I DISCUSSIONS OF PRINCIPLES. 483

powerful dynamic action two uuconformable series, the one of which is 

composed of material from the other and therefore resembles it in composition, may have developed conformable secondary structures and 

gradations, the latter consequent upon the induced crystalline character of the clastic series, the original structures being simultaneously 

obliterated. Also recently Pumpelly has ascertained that suba erial disintegration of the earlier series is an important assistance in the 

production of such gradations. In certain areas it has been demonstrated that perfect conformity and complete gradation exist between 

series separated originally by wide unconformities, the earlier of which 

was probably of igneous origin while the later was certainly sedimentary.

Whatever the origin of the fundamental complex, it is plain that the 

parts of any given area of it are not all of the same age. The dikes 

j which everywhere cut it are the pipes through which have passed the 

later eruptives. At the time of the intrusion of these eruptives, large 

) lakes of liquid material may have formed which crystallized as bosses, 

causing the Archean to contain considerable masses of rocks of really 

later age. Where these rocks are predominant the material must be 

classified as a later eruptive; where they are subordinate to tjie Archean 

material they are often difficult to separate from it although really later 

Jin age. Between the areas which rank as eruptives of later age and 

f the genuine Archean, there are doubtless gradations. Along the zone 

of contact, if the mass of later eruptive be great, there might be an 

' area which could equally well be placed with the fundamental complex 

or with the later eruptive. Between the Archean and later eruptives, 

as between the Archean and undoubted sedimentaries, there are gradations.

The problem of the relations of the Archean as a Avhole to the over- 

' lying elastics is the same as that within the Archean itself. The finely 

laminated crystalline schists and gneisses, and the granite-gneisses and 

. granites with which they are associated, have contacts in every respect 

analogous to those occasionally found between the Archean complex 

and the clastic series. For example, it has been seen that the rocks 

heretofore called Archean on the north shore of lake Huron comprise 

two parts. One part is older than and lies unconformably below, yielding fragments to the original Huronian. The other part has relations 

Avith the elastics of the character just considered with transition phenomena. If this material is an extraneous intrusive it is a post-Archean 

eruptive. If in situ it represents a portion of the pre-Huroniari floor 

completely metamorphosed by selective metamorphism, or by aqueoigneous fusion, it can fairly, according to the first and second school, be 

called a part of the Archean.

It is plain from the great diversity of opinion as to the origin of the 

Archean rocks, and from the fact tha,t many of the opinions are beliefs 

rather than verified conclusions, that we have no definite knowledge
V

484 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

upon parts of the subject. That there are comparatively few or no 

wholly massive rocks in this complex is precisely what would be expected under any theory. Its history is too long. Whether originally 

igneous or aqueous, it could not be hoped that there would be found 

the characteristic lithological forms of igneous or aqueous agencies. 

Many or all of these rocks, not only subject to the movements 

which have taken place since Paleozoic time, but to the movements 

which have occurred in the far greater length of previous time if not 

too deeply buried to be beyond the influence of the outer foldings, in 

which case they were burled beyond the crushing strength of rocks 

were latently plastic, and were probably at a high temperature. If 

originally massive and igneous in the ordinary sense, dynamic action 

has obliterated the regularity of the arrangement of the constituent 

particles and has given them a more or less laminated or schistose structure. If sedimentary, all trace of that original sedimentary structure j 

has been obliterated by the repeated foldings, contortions, and perhaps ^ 

high degree of heat to which they have at various times been subjected. ( 

Of a necessity, through this complex have passed all subsequent erivptives. Doubtless at various places and times in its history, parts of it 

have become practically fluid and from this condition it has again 

crystallized in the forms characteristic of eruptives.

DELIMITATIONS OF AllCHKAN.

It is generally accepted that the Archean has no limit downward. It , 

is the oldest system, and surely includes, if such rocks exist, all of the } 

original crust of the earth. But as denudation progresses, material far 

within the earth approaches its surface, not by intrusion but by gradually rising as a whole. Before reaching the surface the material has 

become crystallized. This original crystallization may have taken place '< 

in or even later than Algoukian time; hence, if these rocks are to be 

considered as belougiug to the age in which they crystallized, the 

Archean grades below into the Algonkian, even as it is believed in 

places to grade above into the Algonkian. The truth of this position 

is not lessened by the fact, if fact it be, that the earth as a whole, subject to sudden strain, acts as a rigid body. Even if true, it is equally 

certain that the crust of the earth, under continued strain, adapts 

itself to it, thus showing real plasticity. But in any case it can not be 

assumed that the rock material deep within the earth, under pressure 

far beyond the crushing strength of any known material, and at a high 

temperature, exists as crystallized minerals. We only know that it has 

these forms when the material rising by erosion nears the surface.

The upper limit of the Archean is not easy to define, and the task is 

rendered more difficult because geologists are not agreed upon the 

origin of the Archean. If either the sedimentary or the subcrustal 

fusion theory of its origin be accepted, there will be found gradations 

from rocks constituting the ancient complex described to rocks having
VANHISE.] DISCUSSIONS OF PRINCIPLES. . 48f)

like relations with elastics of Algonkian and posi-Algonkian time"* 

Upon either of these theories, if sedimentary rocks are only buried deep 

enough, they will pass into crystallines by progressive metamorphism 

or by subcrustal fusion, just as do rocks of Cambrian and post-Cambrian 

age. This the elder Hitchcock so clearly saw that he distinctly said 

that the so-called Laurentian. granites and gneisses of Vermont are probably, in part at least, not older than the fossiliferous series. If the 

Archean be made to include all the thoroughly crystalline rocks below 

pre-Cambriaii elastics, it includes rocks the age of which varies from 

Algonkian to prc-Algonkian. This anomaly is perhaps best met by 

making a more or less arbitrary division between Archean and postArchean crystallines. The natural theoretical plane to choose is the 

beginning of life; tha.t is, to include in the Archean all truly azoic 

rocks. While this suggestion has a plausible sound, we must believe 

that the dawn of life was very gradual and that its traces in its early 

stages are exceedingly sparse, so that there would be great, if not insuperable difficulties in its practical application.

If the third theory, that the Archeaji includes only pre-sedimentary 

rocks, be correct, its upward limit is easy to define; the Algonkian 

begins for each region at the time of the deposition of the first sedimentaries. But there are those who deny the existence at the present 

time of any such ancient rocks, although they concede their existence at 

one time, and they believe that the Archean as thus defined represents a 

vast lapse of time in the history of the earth. This denial of the present 

existence of any rocks of greater age than the oldest sedimentaries is of 

course a pure unverified assumption defended on the ground of probability. If the original crust of the earth be defined as including more than 

the first outer skin, it is a question whether the converse proposition is 

not equally probable. Even if the position be true, the school that believes in the igneous origin of the Archean would still have a large mass 

of rocks for the Archean by shifting their ground so as to include in it 

all the material which in the slow process of inward crystallization has 

now reached the surface of the earth, not by intrusion in the rocks 

above, but by erosion. This position would, however, be controverted 

by those who regard such rocks as plutonic and belonging to the age 

of their equivalent sedimentaries. But in the nature of the case it is 

not possible to designate the particular age to which these rocks belong. 

That there exists upon the surface of the earth a part of the original 

crust of the earth, or its downward continuation by later cooling, can 

hardly be doubted; and since these can never be assigned to any definite period of sedimentaton they might well be considered as Archean. 

At any rate they are a class by themselves which, if not here placed, 

can not be referred to any of the geological periods. Further, this class 

of rocks when in contact with detritals of whatever age, by the very 

hypothesis of their origin must rest nnconformably below them. The 

coincidence that so frequently, if not always, there is really a, great.
486 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

hiatus between the ancient sediineutaries and the basal complex might 

be urged as evidence of the truthfulness of this hypothesis. It is interesting here to remember that Eminons defined pyrocrystalline rocks 

as those due to the consolidation of the earth's crust, which rocks were 

said to increase in thickness by additions below.

Sedimentation must have begun in the earliest seas, while upon 

parts of possible continental areas volcanic materials alone were still 

accumulating. These latter, in accordance with the definition, would 

belong to the Archean. There would be in this case no positive equating one with the other. When later, upon these Archean. rocks contemporaneous with the earlier Algonkian rocks, sedimentaries began to 

form, this would be for this region the opening of the Algonkian. 

However, it is not impossible that all such supposed contemporaneous 

Archean materials may have been carried away by erosion. Certainly 

this would have been the case with a large portion of them, and it follows that this difficulty may be rather theoretical than practical.

The banded and contorted granite-gneiss which serves as a background for the Archean may not improbably be the part which has the 

origin above suggested, while the other parts of the complex may be 

due to subsequent intrusives; the whole being kneaded into their present extraordinary complex relations by repeated dynamic movements 

and other metamorphic influences. This igneous theory of the origin 

of the Archean, modified so as to include the pre-sedimentary original 

crust, if any remains, and the deeper crust which has reached the surface by denudation, perhaps more nearly covers the facts than any 

other as to the relations of the Archean to subsequent rocks, its complex lithological character, the relations of the rock phases to each 

other, and the long history written in the strained, altered, and broken 

mineral constituents. It accords with the idea held by Irving, Bonney, and others, that this earliest crystalline complex was produced 

under conditions differing from those of the rocks of any subsequent 

period.

But the difficulties in the theoretical delimitation of the top of the 

Archean are so great that I prefer to confine myself to a statement of 

some possible solutions rather than to commit myself to any theory, 

although now inclining toward the third theory modified as suggested. 

Although the obstacles are not nearly so great in delimiting later periods, the difficulties of making an exact definition for the Silurian, Devonian, or Carboniferous are so considerable that almost any of those 

given have been found to controvert the facts of some locality. If 

this is the case with reference to these later periods in which so much 

more is known, it should not be surprising that the obstacles to an 

accurate delimitation of the Archean are at present apparently insuperable.

But while it is impossible to make a wholly satisfactory theoretical 

definition of the Archean, it is frequently easy in the field to say with 

a great degree of probability what rocks are Archean and what post-
VANISH:.] DISCUSSIONS OF PRINCIPLES. "

Archeau. For instance, in the Arizona region, as has been seen, above 

the typical Arcliean complex there, is the most profound unconformity, 

upon the upper side of which the rocks are readily recognized elastics. 

From the writer's point of view the same thing is true for a large part 

of the lake Superior region. In the Uinta and Wasatch mountains, 

again, below the quartzites of probable Algonkiau age, is a great unconformity, and then appears the implicated Archeau. In certain other 

regions the separation of the Algonkian and tire Archean is a matter 

of exceeding difficulty. As representative of this class of cases may 

be taken the Front range of Colorado, along the east side of which are 

unmistakable elastics, with an apparent gradation between them and 

the crystalline complex. In the Appalachians, again, where for the 

most part the oldest clastic rocks recognizable are Cambrian, it can 

not be said whether the crystalline complex below is Algonkiau or Archeau. Here the separation of the Cambrian from the pre-Cambrian 

has been accomplished only by a minute and laborious study. The two 

appeared to be in conformity and to grade into eacii other. It is only 

recently that this gradation has been shown byPumpelly to be consistent with a great unconformity between the two. The causes producing this gradation between the Cambrian and pre-Cambrian in Massachusetts (post-Cambrian dynamic action and pre-Cambrian disintegration) may also be found to explain the conformities and gradations between the Algonkian and Archeau.

While it is then not easy to define the Archean, it is plain that the 

discrimination in the field between Archean and Algonkian is a real 

one and should continue to be applied even if its exact theoretical 

meaning can not be said to be certainly known. It has been the custom in the past to refer to the Arcliean practically all crystalline rocks, 

with many semicrystalline rocks which seem to be old, or the age of 

which was not determined. Under this practice vast areas in the Appalachians have been referred to the Archean, which are now being 

placed in the Cambrian, Devonian, and Carboniferous. Doubtless in 

the same way many other areas which have been placed in the Archean 

upon closer study will be removed from it and the rocks distributed 

from the Algonkian upward. At this point a reform, in geology is 

needed. If, for instance, the oldest rocks of clearly recognizable age 

are Triassic, and these Triassic rocks rest upon a complex, the structural relations of which are not studied in detail, this complex should 

be denominated pre-Triassic rather than Archean. A large part of the 

difficulty in getting to understand from the literature the actual facts 

a-s to the occurrences and relations of the crystalline rocks has arisen 

from this practice of using the Archean as the dumping ground for 

everything of unknown age.

STRATIGRAPHY OF ARCHTCAN.

In characterizing the Archean. the methods applicable to its subdivision are clearly pointed out. If no part of it is demonstrably sedi-
488 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

meutary, strnctnral methods can not apply. Its subdivisions must be 

made upon purely lithological grounds. If a part of it is denionstrably 

eruptive the relative ages of these parts may often be ascertained and 

all are necessarily newer than the part not recognized as eruptive, else 

these could not be shown to have this origin. Many attempts to apply 

strati graphical methods to parts of the Archean have been made, but 

they have not thus far been successful. Such attempts have been 

based upon the belief that foliation represents sedimentation, but even 

working upon this erroneous basis it has been stated that the structures are so complicated that little progress has been made. So far as 

attempts to apply stratigraphical methods to this fundamental complex are concerned the conclusions of Whitney and Wads worth are 

very largely true. If their review of the "Azoic rocks" had been confined 

to this basement system, which is perhaps truly Azoic, the conclusion 

as to its indivisibility on a structural basis would have plausibility.

The only division generally applicable to the Archean warranted by 

present knowledge is its separation into (1) fine grained mica-schists, 

feldspathic mica-schists (technically gneisses), hornblende-schists, horn 

blende-gneisses, etc 5 and (2) the granites and granitoid gneisses with 

their associates. The first class is generally dark colored, the second 

light colored. The lithological affinities of the second are with the igneous rocks. -As already indicated, the change from a granite-gneiss 

area to a schistose area is not infrequently a transition. In passing 

from the schists to the granites often veins or dikes of granite are first 

found, or inter!animations of granite-gneiss with the schist. After a 

time the schistose rocks and granite-gneiss are about equally important. Proceeding onward the granite-gneisses become predominant. 

These relations are precisely those already described and interpreted 

by one school to mean that the granite-gneisses are extraneous intrnsives, by another that they are the aqueo-igneous fused sedimentary 

beds in situ, and by a third that they are selectively metamorphosed 

beds. To designate the gneissoid granite part of the Archean the term 

Laurentian has always been employed and is now generally restricted, 

the finely laminated crystalline schists being commonly referred to the 

Huronian. Laurentian under this usage is made to include the implicated granite-gneiss of the basal complex, somewhat regularly laminated granite-gneiss, and also many areas of nearly massive granite, a 

part of which latter may be and probably is of later age than the former. 

The first is clearly Laurentian. It is equally clear that the granitegneisses known to be of later age than Algonkian elastics, like those 

described by Lawson northwest of lake Superior, should be excluded 

from the Laurentian. To place these rocks here is to introduce a new 

principle in geology; i. e., it is giving rocks of recognized eruptive origin a separate term when they should be given the name of their contemporaneous elastics. The eruptives which are contemporaneous with 

the Tertiary rocks are so named. Bocks which cut Tertiary rocks and
VASHIHK.J DISCUSSIONS OF PRINCIPLES. 48!)

(tan not be more, accurately located are called post-Tori iary. In like 

manner the granite-gneisses which are recognized as eruptives of later 

age tlian sedimentaries should be assigned if possible to the age to which 

they belong, and if not, their limitations expressed. This restriction 

of the term Laurentian will undoubtedly eliminate from, it large areas 

of rocks which have heretofore been recognized as Laurentian, but to 

include both, the original granite-gneiss and later granite-gneisses under 

a single time term is but to deliberately continue a confused classification after facts have been discovered which render it unnecessary. All 

were first referred to the Laurentian only because a discrimination as 

to age had not been made between them.

It appears to me that the best use which can now be made of the 

old term Laurentiau is to restrict it to the Archean granite-gneisses, 

including in it no rocks which traverse Algonkian sedimentaries. This 

use of the term Laurentian is different from the original proposal of 

Logan. The original Laurentian is largely and, with the exception of 

the great lower "orthoclase" gneiss, perhaps wholly a series of detrital 

origin, being composed of limestones, quartzites, and regularly laminated gneisses which almost certainly are altered clastic rocks. 

Dawson (Sir William) in a late paper insists that the bedded sedimentary character of this and adjacent series can not be doubted. It 

was natural in the days in which lamination of any kind was by 

most geologists regarded as proof of sedimentation, that the term Laurentian should be carried over to the underlying thoroughly crystalline 

granitoid gneisses. The known area of this latter class has now become 

so great that the elastics of the type series and other elastics here 

placed are insignificant in comparison. The Hastings series, afterwards connected by Vennor with the original. Laurentian, was first 

referred by him to the Huronian, and there is little doubt that this 

series would, if newly found in the great expanse of northern Canada, 

be thus placed. This is still more emphatically true of the .so-called 

Laurentian elastics of lake Mpissing, which were referred to the Huronian by Selwyn. That two groups of rocks were included in the Lau-° 

rentian of Logan, that author early recognized by his subdivisions: 

Lower Laurentian, including the basal granitoid formation ; and Tipper 

Laurentian, including all the limestones, etc. The later work of the 

Canadian survey has emphasized the reality of this division. In recent 

years the practice of the Canadian Survey has been to include all or 

nearly all of the more regularly laminated rocks which may be positively asserted to be of clastic origin, as well as many of which this 

assertion can not be made to the Huronian. The difference between 

the Laurentian of lake Superior and that of Logan's original area was 

early noted by Macfarlaue, Brooks, and Eominger. The last two 

went so far as to suggest that about the lake Superior region it is probable that the Laurentian of eastern Canada is not represented. That 

possibly the fragmental rocks of the Laurentian of the Bast may be
490 FKE-CAMBKIAN ROOKS OF NORTH AMERICA. IBULL.SO.

equivalent to the more crystalline of the fragnientai rocks about lake 

Superior, here called Lower Huronian, was early suggested by Chamberliii. Excluding from the Laurentiau the small areas of elastics here 

referred, and applying the term to the vast areas of rock referred to 

this system during the last forty years would seem now to be the preferable course. This usage accords with the principles of good nomenclature in that it makes the Laurentian a definite unit and avoids the 

anomaly of including under one term two radically different groups of 

rocks.

The fine grained, dark colored schists belonging to the basal complex 

and antedating the Algonkian should ha,ve a name assigned to them 

coordinate, with Laurentian as the other main lithological division of 

the Arch can. If Lawson's Coutchichmg series belongs here this term 

has priority for this place. Lawson, however, regards this series as 

probably sedimentary, although upon this point additional evidence is 

needed. If it turns out that the Coutcbichiiig is sedimentary under 

the classification proposed in this paper the series belongs with the 

Algonkian. As a provisional name for this second division of the 

Archean is proposed the term Marcniscan. This term, like Laurentian, 

is a geographical one derived from Marenisco township, Michigan, south 

of the G-ogebic range, where these rocks have a typical development.

The Archean as a whole naturally occupies a group place in the classification, and its Laurentian and Mareniscan would be systematic in 

their value if they were structural terms. But until the Archean can 

be separated on a structural basis, if it ever ctan be, it will be necessary 

for the purposes of atlas sheet mapping to treat the group as a unit, 

except that lithological divisions may be made. With reference to 

Archean, we are in the same difficulty as with Agnotozoic or Proterozoic, considered belOAV. This group can at present have but a single 

system division, the Algonkiau, because we are not yet able to subdivide the group into systems which can be shown to be general for the 

whole of America.

The anticlinal structure described as generally characteristic of the 

Archean ranges of the west has been based upon the belief that foliation represents bedding, and also on the obsevations that the overlying 

sedimentary rocks often dip away from the axes. The anticlinal structures of the sedimentary rocks and that of the-Archean are independent 

questions. If the Archean as a whole be regarded as of igneous origin, 

it would be expected that a gradation from massive rocks in the cores 

to schistose rocks upon the flanks would be found, for these outer zones 

are the places where the most powerful effects of dynamic action are 

felt, and also the parts where greater interior accommodations of the 

constituent particles are necessary. In dynamo-metamorphic eruptives 

of post-Archean age precisely these relations prevail. The determination of the structure of the Archean cores must wait until the origin of 

the Archean has been determined5 in short, until it is known whether 

structural methods are applicable at all.
VAN HisE.} DISCUSSIONS OF PRINCIPLES. 491

%

.NECESSITY FOH A GROUP JBETWJSKN CAMBJLUAN AND AllCUJEAN.

The Olenellus fauna is taken as the base of the Cambrian. The reasons for thus delimiting the Cambrian below are fully considered by 

Walcott in one of this series of correlation papers and will be summarized on a subsequent page. His results are accepted. The Cambrian fauna in development is far, some biologists say nine-tenths of 

the way, up the life column. This statement, if accepted, implies a 

prior life of vast duration.

Just as another period of life has succeeded the Cambrian, another 

has preceded it. The progress of paleontologie knowledge has of late, 

been, downward. Before there was a recognized Cambrian there was 

a well known Silurian, and it is probable that when all parts of the, 

world become geologically known other faunas will be discovered below 

the Cambrian as distinctive in cha.racter as the Cambrian is from the 

Silurian. If this be done, definite information will be available to correlate rock series of different pa.rts of the world in the time place between the Cambrian and Archean.

If the condition of the globe was such that life existed in pre-Cambrian time, it also was such that stratified rocks could be deposited 

not unlike those of later times, so that the only question which arises 

. is whether any of these stratified rocks now remain in such a condition 

as to be recognizable. The foregoing pages and the literature summarized give a mass of evidence upon this point which is overwhelming. 

Such intervening clastic series do exist below the Olenellus fauna in 

many regions in North America, and in some cases the volumes of rock 

and great intervening erosions represent a lapse of time which may 

be not inaptly compared with a.ll subsequent time. If geological history were to be divided into three approximately equal divisions, 

these-divisions would not improbably be the time of the Archean, the 

time of the clastic series between, the Archean and the Cambrian, and 

the time of the Cambrian and post-Cambrian. In this connection it 

is well to recall that many years ago Logan suggested that the thickness of the Laurentian and Huronian may surpass that of all succeeding formations, and the appearance of the so-called Primordial 

fauna may be considered a comparatively modern event.

It is imperative that some term shall be available to cover the great 

mass of rocks between the Cambrian and Archean. Irving was the 

first to realize and urge the necessity lor such a term and proposed 

for it Agnotozoic. This term implies the existence of life in this system, and the evidence upon this point is conclusive. Life is indicated 

by the presence of thick beds of graphitic limestones, beds of iron carbonate, and by great thicknesses of carbonaceous shales, which are represented by graphitic schists in the more metamorphosed phases of 

the rocks. It 11 as been urged by Whitney, Wadsworth, and others that 

the limestone and graphitic.schists may have an origin other than
492 PRE-CAMBRIAN ROCKS OF NORTH AMERICA.

organic. Whitney and Wads worth have gone so far as to say that 

there is no valid evidence of life in any pre-Potsdam rocks. This was, 

however, before it was generally recognized that the Potsdam is Upper 

Cambrian and that an abundant Cambrian life extends far below. If 

it were true that these limestones and ore beds are no evidence of life 

(and it may be admitted that another origin is possible without implying that it is probable), it will hardly be maintained that the hydrocarbons which occur so abundantly in the little metamorphosed shales 

of the Huronian about lake Superior are other than of organic origin, 

and, if so, the graphitic schists which stand in the same great system 

in the geological column are in all probability only these hydrocarbonaceous shales in a more altered con dition. However, we are not obliged 

to depend upon the presence of these varieties of rocks as the only 

evidence of life. Whether the llozoon canadense found in the original 

Laurentian of Canada is of organic origin will not be discussed here. 

Its literature is voluminous and it is a question which concerns the 

paleontologists. It is doubtless true that many of the specimens which 

have been called Eozoon are results of the forces of crystallization; 

but, admitting this, it does not follow that all of the material called 

Eozoon is of this character. Passing by this question, the pre-Cambrian 

fossils described by Walcott in the Grand canyon of the Colorado 

include: "A minute Discinoid or Patelloid shell, a small Lingula-like 

shell, a species of Hyolithes, and a fragment of what appears to have 

been the pleura! lobe of the segment of a trilobite belonging to a genus 

allied to the genera Olenellus, Olenoides, or Paradoxides. There is 

also an obscure Stromatopora-like form that may or may not be organic."

A Lingula-like shell has been found by Winchell in the pipestones of 

Minnesota. Selwyn has described tracks of organic origin in the Animikie (Upper Huronian) series of lake Superior. Murray, Howley, and 

Walcott found several low types of fossils in the pre-Olenellus elastics 

of Newfoundland.

That these fossils are of organic origin can not be doubted. But while 

many will admit the clastic character of the great groups of rocks considered,and the organic origin of the forms mentioned as well as the 

carbon of the carbonaceous shales and schists, they will say that these 

are merely evidences that the rocks in which they lie are Cambrian. 

The reply to this is that it is a question of nomenclature. If it be premised that all clastic and fossiliferous rocks more ancient than the 

Olenellus horizon are Cambrian it is useless to try to prove that there 

are pre-Cambrian clastic rocks which bear life. It is, however, necessary to recognize that the carrying downward of the term Cambrian 

to cover not only the great thicknesses of rocks which are now included within it, but all pre-Olenellus elastics, will probably make the 

Cambrian as great as or greater than all the subsequent periods put 

together. That this is inadvisable is plain, and the clastic rock masses
TAN HISE.] DISCUSSIONS OF PRINCIPLES. 493

below the Olenellus fauna are so enormous that the proposal to introduce a general term like Agnotozoic as the equivalent of Paleozoic, 

Mesozoic, Cenozoic, to cover this great group is a conservative one. 

Irving foresaw that the term would be objected to because sooner or 

later the life will become to a greater or less degree known, and he suggested as an alternative for Agnotozoic, Eparchean in contradistinction to Archean, which was reserved by him to cover the fundamental 

complex. As the character of the life of this group is already beginning to be known, it seems to me that the term Proterozoic, considered for the place by Irving, but rejected, is prefer able to either 

Agnotozoic or Eparchean.

In a conference of the members of theTJ. S. Geological Survey, called 

by the Director at Washington, these terms were discussed with reference to atlas-sheet-mapping, although there was no question, on the 

part of any one as to the necessity tor some such term. Recognizing 

the impracticability of the certain con-elation with one another of the 

one or more pre-Cambrian clastic series which occur in the various 

regions, and recognizing the fact that for use in mapping a uniform 

j)lan must be adopted, it was suggested that a term of the same class 

as Cambrian, Silurian, and Devonian should be selected for rocks 

here included, and to occupy this place the term Algonldau was 

proposed and accepted. The proposed general scheme of classification 

for the lower part of the geological column is then as follows:

{

Carboniferous, 

Devonian. 

Silurian. 

C ami.) dan. 

Agnotozoic, or Proterozoic .................. Algoukiaii.

Archean.................................... Arcliean.

The introduction of the term Algoukian has been objected to on the 

ground that it will supersede the older term Huronian. In. answer to 

this it may be said that Huronian has not been generally used as 

Algonkiaii is denned, and it therefore does not supersede this term. 

Huronian will be retained for certain of the clastic series of Lake Superior and Canada, as well as for rocks in an equivalentx>osition in. other 

parts of North America and Europe, if such equivalence can be determined, just as before Algonkian was introduced. The Huronian will 

stand as one of the great series of rocks which together make up the 

Algonkian.

DELIMITATIONS OF THE ALGONKIAN.

The further back we go in the history of the world for any given 

region the more frequent have been the changes through which a rock 

stratum has passed, and therefore there is increasing difficulty in determining bounding planes with, sharpness, although in different regions 

rocks of the same degree of metainorphism may differ vastly in age.
494 FKE-CAMBRIAN ROCKS OF NORTH AMERICA. [BTOL.W.

The truth of this is well illustrated by comparing the eastern and western regions of the United States. In the former powerful dynamic 

movements have occurred until late in Paleozoic time, as a result of 

which the Cambrian, Silurian, and Devonian rocks over large areas 

have not been separated from the pre-Cambrian. In certain areas this 

separation has been accomplished, but only by the most accurate and 

painstaking application of modern methods. In parts of Massachusetts and Vermont the areas covered and the results reached have involved an enormous amount of labor, although of late paleontology 

has been an important help in unraveling the problem. Under these 

circumstances how much more difficult would one expect it to be to 

separate the pre-Cambrian clastic series from the Archean!

In parts of the West, where no close folding has occurred since Cambrian time, it is easy to separate the Cambrian from the pre-Cambrian, 

and in regions in which metamorphosing influences have not been at 

work for a still longer time it is easy to separate the pre-Cambrian 

elastics from the Archean. But in other regions this separation is 

made with the greatest difficulty, and doubtless over large areas this 

will never be satisfactorily done. Just as in the Appalachians, in parts 

of which it may be impracticable to separate the Cambrian rocks from 

the pre-Cambrian clastic series, if such exists, so it will be for a long 

time impossible to deeide in some regions upon sharp boundary lines 

between the pre-Cambrian elastics and the Archean. Giving full force 

to this position, it is no reason why the discrimination should not be 

made where it can be.

Eecent work in petrography has demonstrated that dynamic movements and environment, not time, are the important elements in the 

obliteration of clastic characteristics. Dynamic movements also destroy 

the evidences of discordances between series where there have been real 

unconformities. This destruction of the evidence of structural breaks 

comes about largely as the result of an approaching parallelism of bedding, caused by the close folding, but far more important than this is 

the production of a common cleavage and foliation with the simultaneous development of crystalline schists from the newer series. As a 

consequence basal conglomerates are often almost the only means of 

discriminating between the newer and the older series, and if the metamorphosing influences are powerful enough to destroy the pebbled, character of such beds, changing theminto schists or gneisses, as has occurred 

in many places in the Cambrian of the Appalachians, this means of 

detecting a break between series is also lost. The problem is rendered 

still more difficult because of the fact that often when there is a real 

unconformity there has been originally no basal conglomerate. At 

n i ;ti ly localities in the far West the basement fossiliferous series are built 

up of the constituent minerals of the underlying rocks rather than of 

large fragments of them, and even when not folded have sometimes so 

closely simulated the original rocks that geologists have been at a loss
VAK HiGB.] DISCUSSIONS OF PRINCIPLES. 495

to determine at what plane tlie elastics end and the crystallines begin. 

I fit lias proved difficult to separate the unfolded elastics from underlying' crystallines how inucli more difficult must it of necessity be to 

separate series that have together been subjected to intense and perhaps repeated dynamic actions.

The Algonkian hasbeen defined as including all recognizable pre-Cambrian elastics and their equivalent crystallines. In the consideration of 

the character, origin, and delimitation of the Arehean the lower limit of 

the Algonkian has been given. Its basal plane is the lowest of the 

recognizable clastic rocks. It has been seen that there are great differences in the ease of recognition of the basal Algonkian plane indifferent regions. In the Uinta mountains, in the Grand canyon region 

of Arizona, in portions of the lake Superior region, in the original 

Huronian region, and elsewhere, between the Algonkian and the 

Arehean, there are great unconformities, above which are the readily 

recognizable clastic rocks, and below which are the thoroughly crystalline basal complexes. Even in many regions in which there have been 

repeated foldings since Arehean time, and in regions obscured by eruptive activity, it is perfectly clear that a large part of the rocks are 

clastic and belong with the Algonkian, while other parts have all the 

characteristics of the iundamental complex. Occupying an intermediate position are occasionally found areas of rocks which can not certainly be placed with the Algonkian or Arehean, but this difficulty is 

not peculiar to this separation any more than to other general recognized planes, such as that separating the Cambrian and Silurian in 

folded districts. Many of the members of the Canadian Geological 

Survey have described the Huronian and the Laurentian as conformable, with gradations between the two. This apparent accordance and 

gradation is in many cases due to the fact that placed with the Huronian are many rocks which would under the use of the terms here 

proposed be regarded as Arehean. In other cases there are apparent 

conformities and gradations between undoubted elastics and the underlying rocks having all the characteristics of the fundamental complex. 

The significance of these gradations is discussed in another place, 

where it was seen that they are not inconsistent with genuine structural breaks.

It has been stated that the reasons for placing the base of the Cambrian at the Olenellus fauna are considered by Walcott in this series of 

correlation papers, and that his results are here accepted. It is, however, to the point to consider whether this horizon answers equally well 

for the upper limit of the Algonkian. Evidently all the arguments 

brought forward by Walcott for placing this fauna as the base of the 

Cambrian apply as well for considering the horizon below this as uppermost Algonkian; for the widespread character, both European and 

American, of the Olenellus fauna makes it a particularly easy one to 

identify and therefore valuable for the purposes of discrimination. In
496 PRE-CAMBRIAN BOCKS OF NORTH AMERICA. [BULL. 88.

the lake Superior region and in mauy other localities above the upper 

Algonkian are unconformities, the first of the Cambrian being middle 

or upper. In other regions, as in Newfoundland, the upper Algonkian 

is marked by an unconformity, and the formation immediately above 

bears the Olenellus fauna. This is the most favorable and clear case. 

In the Wasatch and several other ranges of Utah and Nevada, in 

British Columbia, and probably in the southern Appalachians, below 

the Olenellus fossiliferous Cambrian are conformable series of qua rtzites and slates of great thicknesses. Are these lowest Cambrian or 

uppermost Algonkian? May not the Olenellus fauna in the future be 

found to extend downward through a greater or less thickness of these 

apparently barren rocks? If in any region the fauna be found to extend downward for a long way, it is probable that species and genera 

characteristic of the Olenellus horizon as now known will drop out and 

others appear which are different. The Olenellus would thus grade 

into a pre-Olenellus fauna. Such a gradation will doubtless somewhere be found, while in other regions the change from an Olenellus 

fauna to one of a pre-Olenellus type may occur abruptly. In either 

case there will finally appear a fauna which is not the present known 

Oleuellus fauna, but which is as different from it as is the Cambrian 

from the Silurian (Ordovician). As the term is here used, such a fauna 

is pre-Cambrian, and the rocks containing it are Algonkiau. In the 

following paragraphs great barren inferior series conformably below 

the known Cambrian are placed with the Algoukian on the ground of 

probability. The presence of an abundant lower Cambrian life at a 

certain horizon within the conformable succession, with apparent complete absence of life in immense thicknesses of rocks conformably below/ 

which, so far as lithological character is concerned, are equally likely to 

bear fossils, throws the weight of evidence in favor of the Algonkian 

age of these rocks. It is, however, more than probable that some part 

of the conformable downward extensions of the Cambrian which are 

here provisionally referred to the Algonkian will in the future be found 

to belong with the post-Algonkian.

The newest Proterozoic or Algonkian rocks of different regions may 

stand in different positions, just as the superior rocks of the Paleozoic 

may in any given region be Cambrian, Silurian, Devonian, or Carboniferous.

DIFFICULTIES IN ALGONKIAN STRATIGBAPHY.

Since among the pre-Cambrian elastics, paleontology is not yet available in correlation, it is exceedingly difficult to make widespread subdivisions of the Algonkian, such as are made in later time. The difficulty is further increased by the unequal metamorphism in different 

regions of series of the same age. The Algonkian is in just such a 

position as regards wide correlation of its constituent series as would 

be the Paleozoic and Mesozoic if their known fossil contents were so
VAN RISE.] DISCUSSIONS OF PRINCIPLES. 497

small as to be useless for the purposes of correlation. The structure of 

individual districts and regions could be worked out and the formations 

correlated, but the attempt to equate the Cambrian, Silurian, Devonian, 

or Carboniferous of one region with rocks of the same age in a far distant one would be an almost hopeless undertaking. In the Carboniferous the beds of coal would serve as an important guide, but if implicitly followed and no fossils were available the Triassic of Virginia, 

the Carboniferous of the central United States, and the Cretaceous of 

the west would be placed together. If the iron carbonate formations 

of the Algoukian in the lake Superior region, which appear to be the 

most characteristic of any one kind of rock, were followed as a guide, 

the results would probably be as far from the truth.

We may, perhaps, go so far in some cases as to correlate series which 

occur in different districts of the same region when a set of characteristic formations forming the series occur in like order and the series as 

a whole is in the same relative position to overlying and subjacent 

series, one or both of which are known to be identical in both districts. 

It is probable, when several pre-Cambrian series occur of the same 

general character, with like relations to each other and to the Archean 

and Cambrian, and not so far apart as to be outside of the same geological basin, that a pro visional correlation is warranted. While, then, 

it is not practicable to subdivide the Algonkian into general systems 

which shall cover the whole of North America, it is often possible so to 

do in a single geological basin, or in adjacent basins in which the relations of the separate formations and series can be worked out.

Before considering the principles applicable to the subdivision and correlation of the Algonkian series, it will perhaps be well to review briefly 

the regions in which pre-Canibrian rocks occur, and indicate their character and relation s, as well as their relations to the Archean. The order 

followed is that of the review of literature. No attempt is made to give 

detailed evidence for the conclusions stated. For this it will be necessary to refer to the fuller accounts of the several regions in the previous 

chapters.

THE ORIGINAL LAURENTIAN AND ASSOCIATED AREAS.

In this region are Algonkian rocks at the following localities: Hastings district, lake Mpissing, Ottawa river, and Upper St. Lawrence 

river. The Grenville area of the Ottawa is the original Laurentian 

type district and the one mapped in most detail. While the maps do 

not connect these areas, the similarity of their clastic rocks is such as to 

indicate a present or former continuity, with the exception, perhaps, of 

those of lake Nipissing. The elastics consist of ititerstratified limestones, quartzites, conglomerates, green slates and schists, micaschists, hornblende-schists, and regularly bedded gneisses, together 

estimated to be thousands of feet thick. Associated with these are 

diatoasic and chloritic rocks, both massive and schistose. 

Bull. 86 32
498 PKE-CAMBEIAN ROCKS OF NORTH AMERICA. [BULL. 86.

In the Hastings series there are found considerable areas of peculiar 

volcanic elastics. Below these rocks is a great complex in every respect 

like the Laurentian Archean as above denned. This latter system, 

called usually Lower Laurentian, occupies the main area of the region, 

and the elastics are in a series of troughs within it. What the relations 

are between the elastics and the fundamental complex has not been 

definitely made out, although Vennor believes that between the two is 

an unconformity, and that the elastics are infolded patches. The evidence given for this is, however, ra.ther meager, and doubtless almost 

as good a case could be made out with present facts for the theory of 

an irruptive contact between the crystallines and the elastics. The 

Labradoritic rocks (gabbros) found in this region need not be considered in the stratigraphical succession, as they are eruptives of later age 

than the clastic series. Besides this eruptive, other acid and basic 

eruptives cut the bedded succession.

To the elastics, Logan, Murray, Vennor, and all who have worked in 

this region recognized that ordinary stratigraphical methods could be 

applied. The persistence of the bands of limestones is such as to enable them to be traced for long distances. Although the problem 

was a dimcult one, a detailed mapping, with sections, has been submitted for a small part of the area. The structural relations and correlations which Vennor first gave differ greatly from his final ones, and it 

may be that even in the areas in which detailed mapping was attempted 

that serious mistakes had been made; but if this be true, the region is 

in no respect different from any other in which the structure is difficult.

All of the pre-Cambrian rocks here found were supposed by the 

Canadian geologists to be lower in the geological column than the 

Huronian of lake Huron. Upon the last point no positive evidence is 

at hand. The two rock series do not come together. In the most western Hastings district of the Laurentian, the elastics, in lithological 

character, degree of crystallization, and amount of folding are intermediate between the Laurentiau and Huronian of the type areas. At 

first the Hastings elastics were correlated by Vennor with the Huronian, and with this correlation certain of the official Canadian geologists 

now agree, but afterwards they were traced with breaks of not very 

great distances to the original Laurentian area and have always been 

thus mapped.

THE ORIGINAL HURONIAN.

The Original Huroniau of the north channel of lake Huron consists 

of comparatively little-altered quartzites, slates, slate-conglomerates, 

graywackes, cherts, and limestones having a total thickness of 18,000 

feet, counting considerable masses of interstratified greenstone which 

are recognized as eruptives. Kecent observations render it probable 

that these rocks are to be divided into two unconformable series, the 

lower of which is 5,000 feet and the upper 13,000 feet thick. The first
VAKHISK.J DISCUSSIONS OF PRINCIPLES. 499

would thus be properly designated as Lower Huronian and the second 

as Upper Huronian. Although cut locally by later granites, the lowest 

member of the inferior series is separated from the basement complex 

by a great unconformity. The upper members rest uucoiiformably 

below the Potsdam sandstone. The upper series is so gently folded 

that the careful work of Logan and Murray enabled them to map these 

rocks in detail and to work out their structure. This has been done 

for a considerable district with as much certainty and accuracy as in 

many areas among the fossiliferous rocks. The rocks were divided into 

a number of formations, which were found to be persistent throughout

1 the district. They were traced as a broad belt for several hundred

miles in a general direction northeast. Along the Canadian Pacific

) rail way as far as Sudbury and in the vicinity of Sudbury more than a

; general study of tliis great area has been made. The clastic rocks of 

ithis part of the region have the same general character as the type 

I/district, but in the Sudbury district there are peculiar contemporaneous 

/volcanic elastics. In the little studied remainder of the region, as

./mapped, numerous granitic and giieissic areas are included, some of 

which may be subsequent intrusives, but many of which probably rep-

^esent the underlying Archean.

LAKE SUPERIOR REGION.

In the lake Superior region, between the Archean and the Potsdam sandstone, the great Algonkian system is subdivided into three 

series, which are separated by very considerable unconformities. The 

lowest series is closely folded, seinicrystalline, and consists of limestones, quartzites, mica-slates, mica-schists, schist-conglomerates, and 

ferruginous and jaspery beds, intersected by basic dikes, and in certain 

, areas also by acid eruptives. It includes volcanic elastics, often agglomeratic, and a green chloritic, finely laminated schist. The thickness of 

this series has not been worked out with accuracy, but at its maximuni it is probably more than 5,000 feet. As the term Huronian has 

been for many years applied not only to the Upper Huronian series, but 

to this inferior series about lake Superior, it is called Lower Huronian.

Above this series is a more gently folded one of conglomerates, quartz1 ites, shales, slates, mica-schists, ferruginous beds, interbedded and cut 

by greenstones, the whole having a maximum thickness of at least 

12,000 feet. In the Aniniikie district a fossil track has been found, and 

in the Minnesota quartzites lingula-like forms as well as an obscure trilo- 

, bitic-looking impression. Carbonaceous shales are abundant. In its volume, degree of folding, and little altered character the Upper Huronian 

is in all respects like the upper series of the original Huronian, and 

can be correlated with it with a considerable degree of certainty. Above 

the Upper Huronian is the great Keweenawan series, estimated at its 

maximum to be 50,000 feet thick, although its average thickness is 

much less. Its lower division consists largely of basic and acid vol-
500 PRE-CAMBRIAN EOCKS OF NORTH AMERICA. [BULL. 86.

canic flows, but contains thick beds of interstratified sandstones and 

conglomerates, especially in its upper part. The upper division, 15,000 

feet thick, is wholly of detrital material which is largely derived from 

the volcauics of the same series.

The unconformity which separates the Lower Huronian from the 

Upper Huronian and that which separates the latter from the Keweeuawan each represents an interval of time sufficiently long to raise the 

land above the sea, to fold the rocks, to carry away thousands of feet 

of sediments, and to depress the land again below the sea. That is, 

each represents an amount of time which perhaps is as long as any of 

the periods of deposition themselves. In parts of the region the lowest 

clastic series rest unconforniably upon the fundamental complex, but 

ILL certain areas the relations have not been ascertained. The upper of 

the three clastic series, the Keweenawan, rests unconformably below 

the Cambrian.

In the lake Superior region it has been possible with a considerable 

degree of certainty to refer the detached areas of pre-Oambrian clastic < 

rocks to one or another of the three series mentioned, although there 

have been sharp differences of opinion with reference to certain of the 

areas. It has been possible further to subdivide the series into formations, some of which have a widespread extent within the region. The - 

best results in correlating the subdivisions within the series have been 

reached in the Penokee and Animikie districts.

Correlations of series in this region have been based upon unconformity, upon lithological similarity, upon the belief that the greater 

dynamic movements which have affected the region have been widespread, and upon degree of crystallization of the rocks. The correlation of the formations within a given series has been based upon lithological characters and upon a similar succession of like beds.

THE EEGION ABOUT HUDSON BAY.

Within the main Canadian area of pre-Cambrian in the region about 

Hudson bay exist several troughs in which there certainly occur fragniental rocks such as slate-conglomerate, limestone, and dolomite. 

These are associated with "imperfect" gneisses, a great variety of 

schists, and schistose and jaspery iron ores. The Marble island series, 

with that of the adjacent shore, is closely analogous in lithological 

character to the Upper Huronian, while the more crystalline phases 

resemble the Lower Huroniau. The chief indication available as to 

the relations of these rocks to the basal complex is the presence in the 

slate-conglomerates of syenite pebbles, like the rocks of the underlying crystallines. Besting unconformably upon the foregoing elastics and upon the basal complex is the Manitounuck series, which 

consists of siliceous and argillaceous limestones, sandstones, quartzites, shales, ironstones, with interbedded amygdaloids arid basalts, 

all the members of the series beiiig in a practically uninetainorphosed
VAN HISE.] DISCUSSIONS OF PRINCIPLES. 501

condition. This series, in its structural and lithologicttl characteristics is remarkably like the Keweenawan of lake Superior, and its distance from the nearest area of this series, the Nipigon, is not very 

great, so that its correlation with the Keweenawan can be made with 

a fair degree of probability. There are then, about Hudson bay, between 

the Cambrian and the Archean, at least two, and perhaps three, series 

of rocks, the uppermost of which rests upon the lower series unconformably.

OTHER REGIONS OF NORTHERN CANADA.

Too little is known of the vast expanse of pre-Cambrian rocks which 

constitute the northern parts of Canada to make any definite statements. It is, however, evident that rocks lithologically like the 

Archean of the previous regions discussed constitute the great area. 

,J It is equally plain that within this area, at various districts, are rocks 

I which show undoubted evidences of clastic characters as shown by the 

I presence of limestones, schistose conglomerates, volcanic elastics, etc., 

which have a lithological likeness to the Keweenawan, Upper or Lower 

Huronian of lake Superior, but which can not yet be closely located. 

The Huronian area of the north channel of lake Huron extends to an 

 "unknown distance in a north and northeast direction. Also, it is by 

no means certain that many of the rocks referred by Dawson to the 

Cambrian are not really pre-Cambrian, as used in this essay. The 

Coppermine series, for instance, in its lithological character and position, is such as to lead to a comparison of it with the Keweenawan or 

Animikie of the lake Superior, or both. But the structural work in 

this vast area can be considered but as barely begun.

THE EASTERN TOWNSHIPS.

In the Eastern Townships there is unconforniably below the fossiliferous Cambro-Silurian a series of little altered slates which rests unconformably upon crystalline or semicrystalline schists. These have been 

regarded by the Canadian geologists as Lower Cambrian, although in 

them no fossils have been found. In position and lithological character they are compared with the gold-bearing slates of Nova Scotia. As 

the Canadian Geological Survey uses the term Cambrian, including the 

Animikie and Keweenawan, this series is probably Cambrian, but, mak- 

. ing the basal Cambrian as is done in this essay the series bearing the 

Olenellus fauna, it is probable, although not certain, that this series of 

slates is pre-Cambrian and Upper Algonkian. Of the series of schists 

unconforniably below this series there are no very full descriptions. It, 

however, includes iiiica-slates, staurolitic schists, crystalline limestones, 

argillites, and graphitic schists, and with these volcanic elastics. This 

is certainly a clastic series in part at least. The whole is associated with 

granites which are regarded by Ells as intrusives in the schists, and 

one of the causes of their metaniorphism, but by Sehvyii. are supposed
f)02 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL.86.

to be the clastic series in a more metamorphosed condition. In this 

region it is probable that the fundamental complex does not appear, 

the lowest series found being a clastic one which is to be placed in 

the Algonkian. The lithological character of the Lower Algonkiau 

crystalline series more nearly resembles the Upper Laurentian of the 

original Laurentian area than any other. The unmetamorphosed slate 

and quartzite series unconformably above it can not now safely be correlated with any of the clastic series to the west. It may be that it is 

Upper Huronian or later.

SOUTHERN NEW BRUNSWICK.

In southern New Brunswick, while the geology is exceedingly complicated, and the later conclusions of the official geologists differ fundamentally from those earlier held, it is plain that there exists here a preOambrian clastic series of great thickness. The wholly crystalline gran - 

ites, gneisses, etc., at the base, in their general lithological description, 

resemble the Archean of the West, but from present evidence it is ini-: 

possible to decide whether these are subsequent intrusives, the product of complete metamorphisni of the clastic series, or are a basement 

complex. The geologists who have described the region clearly maintain that this series is more ancient than the oldest associated clasticsj' 

although the relations strongly suggest the possibility of an eruptive 

contact between the latter and the granites and gneisses. The older 

series of elastics, called the Upper Laurentiau, does not have a great 

thickness, consists of quartzites, slates, and crystalline limestone interstratified with argillites, slate-conglomerates, and gneisses. This 

series in its lithological character is like the original Upper Laurentian. Above it, conforming with this series and the granites and 

gneisses, is the Coldbrook series, which is very largely composed of surface volcanic flows and elastics. Above this are the Coastal and Kingston series, which are wholly unmetamorphosed clastic rocks, associated 

with contemporaneous eruptives. Between the two is something of an 

unconformity, but it is not thought by the Few Brunswick geologists 

to have marked a considerable epoch of time. The two upper series can 

not certainly be correlated with series in other parts of Canada and 

about lake Superior, but not improbably they belong above the horizon 

of the Lower Huronian, being perhaps equivalent to the Upper Huronian or Keweeuawan, or with the erosion intervals which separate these 

series.

NOVA SCOTIA AND CAPE BRETON.

In Cape Breton the relations between the basal complex and the 

George river limestone series are identical with those between the basal 

complex and the so-called Upper Laurentian of southernNew Brunswick; 

i. e., there is here a clastic series and a granitoid gneiss series in which 

it is impossible to say definitely whether the relations are those caused
VANHISE.] DISCUSSIONS OF PRINCIPLES. 503

by an eruptive contact or whether the crystalline complex is older than 

the clastic series, the latter being deposited upon it.

In Nova Scotia the great gold-beadng series of the Atlantic coast, of 

unknown thickness, mapped by the Canadian Survey as Cambrian, 

may be pie-Cambrian as terms are here used. It contains the evidence 

of life in Eophyton, but this does not forbid regarding it as Algonkian 

in our sense of the term. The series may be as high as the Cambrian, 

or it may be the equivalent of one or more of the pie-Cambrian series. 

In this region the relations of the granites and gneisses to the goldbearing slates are such as to demonstrate with a reasonable degree of 

probability that the granites are intrusive, although they have been 

regarded by certain, writers as metamorphic. This fact suggests that 

a part of the granite of the fundamental complex of southern New 

Brunswick and Cape Breton may also be a later eruptive, but even if 

this were the case it would not demonstrate the absence of an earlier 

granite-gneiss series.

NEWFOUNDLAND.

In Newfoundland is a clear case of a great series of rocks of perhaps 

10,000 feet thick, referred to the Huronian by Murray, which is a part 

of the Algonkian. Here is found the Olenellus fauna in the basal Cambrian rocks, and these are separated by an unconformity from the undeiv 

lying clastic series, in which, however, has been discovered two or three 

fossils of a low type. What the relations of this lower slate series are 

to the crystalline granite-gneiss which has been referred to the Laurentian is uncertain. No evidence is available, showing that lower 

than this slate series are any elastics. Certain of the granites of the 

island of Newfoundland are iutrusives of later .age than the slates, some 

of them being as recent as Carboniferous; so that it is not impossible 

that many of the granites, syenites, and porphyries referred to the Laurentian may be of far later age.

THE BLACK HILLS.

In the Black hills is a great series of slates, quartzites, quartzose 

conglomerates, mica-schists, and mica-gneisses of unknown, although 

probably of great, thickness. These are cut both by intrusive granites 

and basic rocks of Algonkian age and by eruptives of later time. All 

of the clastic rocks are more or less metamorphosed by the contact and 

dynamic action to which they have been subjected, and adjacent to the 

great batholites of granite they have become thoroughly crystalline. 

In degree of folding, crystalline character, and mineral composition 

they resemble the Lower Huronian of the lake Superior region nearer 

than any other series. They are separated from the Potsdam sandstone by a very great unconformity, that formation resting upon them 

in a wholly unfolded condition, while the prominent secondary structures of the underlying series a.re nearly vertical and the bedding is in 

a series of sharp folds, No pre-Algonkian rocks are here known.
504 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BUM,. 86.

MISSOURI.

The Algonkian elastics of Missouri are a group of isles surrounded 

by Paleozoics. They consist of limestones, slates, iron ores, and conglomerates, the most of the debris of which is from porphyries and are 

interbedded with surface quartz-porphyry flows, which make up the 

greater part of the volume of the series. There are here also granites, 

which are probably of the same age. If this is the case no rocks older 

than the Algonkian are here known. The series shows conclusive evidence of vast denudation before the horizontal Cambrian was deposited 

upon it. The lithological character of the series is intermediate between the Upper Huronian and Keweenawan of the lake Superior 

region, and it may stand as the equivalent of one or the other of these, 

or in an intermediate position.

TEXAS.

In Texas the Algonkian is represented by the Llano series of Walcott or the Texian series of Oomstock and by the Fernandian of Cornstock. The first series consists of gently folded shales, sandstones, 

limestones, and schists with ferruginous beds, and is cut by both basic 

and acid eruptives. It is for the most part very little metamorphosed, 

and is said to repose unconfonnably upon the Fernandian. The Fer- 

^nandian series consists of quartzites, ferruginous rocks, carbonaceous 

schists, chloritic slates and shales, calcareous rocks, and other acidic 

and basic schists. It is now a rather crystalline series, but it is clearly, 

in part at least, of clastic origin. The series is cut by numerous eruptives, both basic and acidic, of which granite is the most prominent. As 

to the relations of the clastic series to the Burnetian (Archean), they 

are believed by Comstock to be unconforinably above it. They are 

separated by a great unconformity from the Cambrian sandstone. 

Comstock correlates the Texian with the entire Grand canyon clastic 

section, which, if true, and the above supposed relations correct, make 

the Fernandian rather low Algonkian.

MEDICINE BOW RANGE.

In the Medicine Bow mountains, the clastic series of Medicine and Mill 

peaks, consisting of slates, cherts, siliceous limestones, quartzites, and 

conglomerates, all of considerable thickness, appear to be conformable 

with the more crystalline granite-gneiss complex. The only evidence 

that there is a break between the two is the presence of granite and 

gneiss fragments in the lower parts of the clastic series. In degree of 

crystallization and lithological character this Algonkian series is like 

the Lower Huronian of the lake Superior country.

SOUTHWESTERN MONTANA.

In southwestern Montana, the Algonkian is probably represented by 

two series. The upper series consists of 12,000 or 15,000 feet of uual-
YANHISE.] DISCUSSIONS OF PRINCIPLES. 505

tered strata, mostly shales. TJie lower consists of completely crystalline regularly bedded gneisses, qua,rtz-schists, quartzites, chlorite schists 

and mica-schists. The upper series, the topmost of the Algonkian, is 

separated from the Archean by a great unconformity. The relations 

of the lower series of the Algonkian to the basal complex are unknown, 

but it is known to lie unconformably below the Cambrian. Also the two 

Algonkian series are not found in contact, but that there are two series 

is indicated by the facts that one of them is conformably below the 

Cambrian while the other is not, and the first is nearly unaltered while 

the second is crystalline. There is no sufficient information upon which 

to correlate either of the Algonkian series with the region about lake 

Superior. The affinities of the Upper Algonkian are rather with probable Algonkian series to the west yet to be considered.

THE UINTA MOUNTAINS.

An ancient clastic series in the Uinta mountains covers an. area of 

several thousand square miles. This series, 12,500 feet in thickness, is 

one of red quartzites and sandstones, interstratified with layers of slate 

and ferruginous shale. It rests upon the upturned, truncated edges 

of a thoroughly crystalline complex which is probably the equivalent of the Archean of other regions. It is unconformably below the 

Carboniferous. There is, then, no definite evidence upon which this 

series can be referred to the Algonkian. It, however, in lithological 

character, absence of fossils, and position, is more nearly analogous 

with the quartzite series of the Upper Huronian than any other to the 

east, but the distance which separates it from the Upper Huronian is 

so great as to render correlation on this ground very unsafe. The series 

ma,y, with more probability, be regarded as the equivalent of the slates 

of southwestern Montana and the probable Upper Algonkian of the 

Wasatch to be considered. Also it is possible that it may not be Al gonkian at all, but Cambrian or Silurian.

THE WASATCH MOUNTAINS.

In the Wasatch mountains the Algonkian is probably represented 

by one series, and perhaps by two. The supposed Upper Algonkian is 

a series of quartzites, sandstones, and micaceous shales and in ica-schists 

12,000 feet in thickness. It is possible that below this series, separated 

by an unconformity, is another more ancient and crystalline series which 

belongs with the AJgonkian, represented by the small area of quartzites and quartz-schists at the foot of the Cottonwood canyons. The 

Upper Algonkian is separated by a great unconformity from, the Arch ean. 

Its relations to the supposed older series of elastics in the lower Cottonwood are not made out, but it rests conformably under the Olenellus 

Cambrian, and therefore if not Cambrian is uppermost Algonkian. This 

series occupies the same position as the series of slates in southwestern 

Montana, and the two, as has been said, are perhaps the equivalent of 

the Uinta series. -
506 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [HULL. 88.

PROMONTORY RIDGE, ANTELOPE AND FREMONT ISLANDS.

Tn this range are a series of mica-schists, quartzites, argillites, which 

are occasionally calcareous, rocks which are probably clastic and therefore represent the Algonkian. The relations of this series to the Archean complex are not known. At Promontory point it rests unconformably under the Weber. The rocks on Antelope and Freinont islands are regarded as of the same age because of their likeness to the 

Promontory point rocks and they are believed to be pre-Cambrian 

because no Cambrian or post-Cambrian rocks in this region are more 

than indurated.

THE AQUI MOUNTAINS.

In the Aqui mountains the probable Algonkian consists of a series 

of quartzites 6,000 feet thick containing beds of conglomerate with 

argillaceous schists and imperfect mica-schists. This series rests upon 

the granite, which is presumably a part of the basal complex. It is 

conformably below the basal Cambrian, stands as Upper Algonkian, 

and may be correlated with the Wasatch Algonkian.

SCHELL CREEK, EGAN, POGONIP OR WHITE PINE, AND PlRON RANGES.

In the Scliell creek range the probable Algonkian is represented by 

heavy bodies of quartzite. In the Egan range the probable Algonkian 

is represented by a series of thoroughly vitrified quartzites several 

thousand feet thick, containing quartzitic and micaceous schists. In 

the Pogonip range it is represented by micaceous, arenaceous, and 

argillaceous slates and shales and by vitreous quartzite, the series be. 

ing of undetermined thickness. In the Pinon range it is represented 

by quartzites underlain by mica-schists and quartzitic schists having 

a total thickness of 5,000 feet. In all of these ranges these series rest 

unconformably upon the Archean and are conformably under basal 

Cambrian. They therefore are probably Upper Algonkian and stand 

as the equivalent of the Wasatch Algonkian.

FRONT RANGE OF COLORADO.

In the district of Balston, Coal, Boulder, and Thompson creeks of 

the Front range of Colorado the Algonkian is represented by quartzites, quartz-schists, mica-schists, and schist-conglomerates, the thickness of the series being unknown, but certainly more than 1,000 feet. 

The series has become very nearly crystalline. Its structural relations 

to the basal complex are not surely known. It apj>ears to grade downward into these rocks, but this may be merely a superinduced conformity. The series of schistose rocks in the Front range, referred by 

King to the Huronian and estimated at 25,000 feet thick, probably 

belong in la.rge part to the fundamental complex.
VANHJSE.] DISCUSSIONS OF PRINCIPLES. 507

THE QUAUT/ITK MOUNTAINS.

In 'the Quartzite mountains the Algonkian is represented by a series 

of quartzites, interstratifted with slates several thousand feet thick. 

The series had suffered powerful dynamic action, being turned on end 

and deeply truncated before Carboniferous time. The relations of this 

series to the Archean are not certainly known, but all the evidence 

points toward the conclusion that the Algonkian is of later age and 

that between it and the Archean is a great unconformity.

GRAND CANYON OP THE COLORADO.

The Algonkian in the Grand canyon region is represented by three 

series, the Chuar, the Grand canyon, and the Yishnu. The Chuar 

series consists of shales and limestones, over 5,000 feet thick. It contains a fauna of a pre-Cambrian type, including at least five distinct 

forms. The Grand canyon series is of sandstones, with basic lava flows 

in its upper part, and is nearly 7,000 feet thick. The Vishnu series consists of bedded quartzites and schists, cut by intrusive granite, and is 

known to be at least 1,000 feet thick, but how much thicker lias not 

been determined, as it has not been measured to its base. The Ohuar 

rests upon the Grand canyon and between the two is a minor unconformity. The Grand canyon rests upon the Vishnu and between the 

two is another unconformity. The Ohuar and Grand canyon sediments 

are wholly unmetamorphosed, while the Vishnu sediments are indurated 

quartzites and semicrystalline schists. Between these series as a whole 

and the underlying Archean complex is a very great unconformity. 

Between the Ohuar and the Tonto sandstone (Upper Cambrian) there 

is another unconformity sufficient to have caused the cutting across of 

at least 10,000 feet of the flexed beds of the Grand canyon and Chuar 

series. In this region is the fullest known succession of Algonkian 

rocks in the United States, with the exception of the lake Superior region. The statement would not be warranted that the series here found 

stand as the equivalent of like series in the latter region, but there is 

a remarkable lithological likeness both in the detrital and eruptive material of the Chuar and Grand canyon to the Keweenawan. Also these 

series occupy a position of unconformity below the Upper Cambrian, as 

does the Keweenawan, and is separated by an unconformity from a 

series of quartzites and quartz-schists which are analogous to the 

Huronian. This latter, Vishnu series, is not well known, so that it is 

unsafe to assert whether it is nearer like the Lower or the JJpper 

Huronian of the lake Superior region.

BRITISH COLUMBIA.

The recent work of Dawson appears to show that in British Columbia there is a widespread series of Algonkian of great thickness. It 

consists of argillites, argillite-schists, quartzites, conglomerates, and
508 PRE-CAMBRIAN ROCKB OF NORTH AMERICA. [BULL.86.

limestones. Between this series and the Archean there is evidence of 

a great physical break, although, the two are in apparent conformity. 

The series in one section rests conformably below the Olenellus Cambrian and the whole is regarded by Dawson as Cambrian, but as terms 

are used in this paper it is probably in part or in whole Tipper Algonkian. By Dawson the series is compared with, the Wasatch Algonkiau 

and the Chuar and Grand canyon series.

THE ADIKONDACKS.

In the Adirondacks is a core of gabbro about which, in a peripheral 

manner is a great series of-regularly bedded gneisses, quartz-schists, 

and crystalline limestones which are often ferruginous or graphitic. At 

times in the gneissic series are beds of graphitic schist of sufficient 

richness to serve as graphite mines. While the interior structure of 

the rocks of this series now shows no positive clastic characteristics, 

the limestones, graphitic schists, and regularity of what appears to be 

bedding in the gneisses leave but little doubt that the series was originally clastic and belongs with the Algonkian. The studies of Walcott 

render it probable that there is here also a basal complex, and along the 

contact lines of the series Walcott has discovered evidence of an unconformity. This Algonkian is so remarkably like the not far distant 

original Tipper Laurentian in the neighborhood of Ottawa that one 

can not doubt that the two are or once were continuous.

OTHER ALGONKIAN AftEAS.

Besides the foregoing list of areas in which it is certain, or nearly 

certain, that there are Algonkian rocks, the indefinite knowledge 

available of many other districts indicates the presence of series which 

probably fall within this period. In much of the work in the West the 

pre-Cambrian rocks are treated as a unit, being spoken of as the 

metamorphic group, absolutely no attempt being made to treat them 

upon a structural basis. This was natural in pioneer work, but the 

fact that so many extensive areas of pre-Cambrian elastics have been 

discovered in districts where closer work has been done, suggests that 

in the future there will be discovered many new series of pre-Cambrian 

elastics. The most extensive areas which will be found to swell this 

system will doubtless be found in the vast stretches of pre-Cambrian 

rocks of Canada, but similar series may be found in central New Brunswick, in Gasp6 peninsula, in the Wind river and Teton ranges of Wyoming, in a number of the desert ranges of Utah and Nevada, in Southern California, and in the Appalachians. In this last and most difficult 

region, the recent work of Prof. Pumpelly's corps appears to indicate 

that a subdivision of the pre-Cambrian will be accomplished in Vermont, and it is rather probable that in the southern Appalachians are 

areas of pre-Cambrian elastics.
VANHISE.J DISCUSSIONS OF PRINCIPLES. 509

SUBDIVISIONS OF ALGONKIAN.

The foregoing review of the occurrences of pre-Cambrian clastic 

rocks makes apparent the propriety of introducing the term Agnotozoic or Proterozoic to cover the series between the Paleozoic and 

Archeau. The desirability of dividing the group into several systems 

is also apparent, but it is equally apparent that our limitations of 

knowledge at the present time make it impossible to do this for the 

whole of North America, hence, as with Archean, it is unavoidable 

that a single system term shall be used for the Proterozoic group, and 

as already explained, Algonkian is given this place. However, the 

major subdivisions of this Algonkian system, in volume of rocks and 

time duration, are equivalent to the systems of the Paleozoic. For instance, the Keweenawan, Upper Hurouian, and Lower Huronian series 

of lake Superior are each of them parallel in volume to the Carboniferous, Devonian, Silurian, or Cambrian. The same may be said of the 

Grand Canyon and Chuar series. If in the future it shall be possible to 

subdivide the Agnqtozoic or Proterozoic group on a systematic universal basis, as the Paleozoic is subdivided, the term Algoukian must be 

replaced by Wasatchian, Keweenawan, Upper Huronian, Lower Huronian, etc.

COMPARISON WITH OTHEK CLASSIFICATIONS.

The major classification proposed in this paper differs in some 

.respects from any previously given, although it accords closely with 

that advocated by Irviug, and does not differ radically from that 

proposed by Selwyn in 1879, but afterwards abandoned. Irving did 

not recognize that within the formations called Huronian there is a 

structural break, which properly divides them into two series, Upper 

and Lower Huronian, although lie realized that unconformably below 

rocks which he denominated Huronian are elastics, which were supposed to be inseparable from the Laurentian. As a consequence of 

tliis and of the failure to appreciate that in this lower series, as well as 

in the Upper Huronian, there are abundant evidences of life, he excluded from the Agnotozoic a part of this Lower Huronian, placing 

it with the elastics of the original Laurentian. In the lake Superior 

Lower Huronian there are carbonaceous and graphitic schists and 

beds of iron carbonate. In the original (Middle) Laurentian of the 

East there are great beds of limestone, regularly bedded gneisses, 

quartzites, quartz-conglomerates, graphitic schists, and also very 

graphitic limestones. While the evidence of life is not quite so conclusive as with the Upper Huronian, it is so strong that one who 

believes in its existence in the latter series can hardly doubt its existence in the Lower Huronian of lake Superior and the Laurentian of 

the East, although no fossils universally recognized as such, nor any 

hydrocarbons have been discovered. The reasons for the introduction
510 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 88.

of the term Agnotozoic to cover the Keweenaw, an Upper Hurouiau 

and equivalent series as clearly demand that it shall also cover other 

pre-Cambrian clastic series. Once started on the downward way toward the fundamental complex there is no plane at which to stop until 

this is reached.

This places the boundary between the Proterozoic and Archeau at 

the plane placed by Selwyn between the Laurentian and Huronian. In 

the regions in which Selwyn and most other Canadian geologists have 

studied, they in general find no unconformity between the Huroniau 

and Laurentian. It has been seen that similar apparently conformable 

relations and gradations obtain in various areas in the United States. 

However, in many cases, as has been seen, there are easily discoverable structural breaks between the Proterozoic and Archean.

As to the positions of Whitney and Wadsworth and Hunt, my conclusions are so radically different that little need be said. The reasons 

for the conclusions reached have appeared in the summary of the literature and in this discussion. To attempt to disprove the positions of 

these authors would be merely to repeat the arguments already presented. It may, however, be remarked that both of these positions can 

not be correct, and recently Wadsworth has found evidence which has 

led him to change entirely his views from those expressed in the "Azoic 

System." One maintained the absolute indivisibility and complete 

lack of life in all pre-Potsdam rocks, while the other maintained an 

invariable aqueous succession of pre-Cambrian rocks, consisting of 

seven different series, separated by unconformities. The position here 

taken is in some degree intermediate, that is to say, there is abundant 

evidence of various pre-Potsdam clastic series which bear the evidence 

of life, but no reason in the facts of occurrence nor in the principles of 

geology which indicates for all regions an invariable succession. It is 

not worth while to discuss whether in 1884, the time when Whitney 

and Wadsworth's account of the Azoic rocks appeared, evidence was 

available which would prove the divisibility of the pre-Potsdam rocks. 

If any one desires to answer this question for himself he will consider 

only that part of the literature which was extant prior to this time. 

This comparison will show that within the last decade has appeared a 

volume of evidence upon the existence of pre-Potsdam life and upon the 

divisibility of the pre-Cambrian rocks which far surpasses that obtained 

before. At the present time the evidence in favor of these positions is 

simply overwhelming. With the discouraging view taken by Whitney 

and Wadsworth as to the state of pre-Cambrian geology, I have had 

no sympathy. They said that the chances of "having at some future 

time a clear understanding of the geological structure of northeastern 

North America would be decidedly improved if all that has been written about it were at once struck out of existence." Crude methods 

have frequently led to crude results, but often even in unsatisfactory 

reports are contained facts which serve as clews to later workers. Fur-
VANHISB.) DISCUSSIONS OF, PRINCIPLES. 511

ther, much that was written before the present decade is as good work 

in proportion to the light at hand the only proper method of comparison as any since. The only way to get well on a road or to a goal is 

to start. Also it must be insisted, in opposition to Whitney and Wadsworth, that stratigraphy and classification are possible without paleontology. Both of these preceded this branch of geological science, and 

paleontology is useful only as it is guided by stratigraphy. Forgetting 

this, fossil evidence has frequently been misused. In dealing with the 

pro-Cambrian rocks we are exactly in the position that geologists are 

among the post-Cambrian rocks where fossil evidence is lacking. Each 

district must be studied stratigraphically by its formations and discordances. The lack of fossils is most keenly felt in correlation. However, 

the protests of Whitney and Wadsworth against many of the subdivisions of the pre-Cambrian and the principles upon which they were 

made are well founded.

As to the supposed invariable aqueous succession of Hunt, the writer 

can only say that so far as he is familiar with North America he knows 

of no region in which this succession does occur in its fullness; while 

every complex region with which he is familiar contradicts it at one or 

more fundamental points. As one illustration among many which might 

be mentioned, the Labradorian, supposed to be a part of the invariable 

succession, is demonstrated beyond all question to be an eruptive rock. 

Large areas of this rock are associated with or underlie the earliest 

pre-Cambrian and it also occurs in the form of great flows in series as 

late as the Keweenawan. The whole scheme is one which is highly 

theoretical and seems to have been evoked by laboratory study rather 

than from a consideration of the actual rock successions within the 

pre-Cambrian in the field. The chance that a scheme evolved in this 

manner should accord with the facts of the world is indefinitely small.

PRINCIPLES APPLICABLE TO ALGONKIAN STRATIGRAPHY,

The clearest discussion of the principles which, from the writer's 

point of view, are most applicable to the classification, correlation, and 

mapping of the pre-Canibrian rocks are the structural and lithological 

principles enunciated by Irving, Pumpelly, and Dale. Accepting these 

in the main, a few supplementary remarks may be made.

In the stratigraphical work of the pastj methods have oftentimes 

been defective. Instead-of giving close lithological descriptions of a 

series of rocks, noting carefully the relations of the different strata, in 

case they are found to have strata, to each other, and giving a detailed 

account of the relations which actually obtain between the series considered and surrounding series, writers have too often called the rocks 

of regions far distant from the original localities to which the terms 

have been applied Laurentian, Huronian, etc. Sometimes this is done 

on the ground that a series as a whole has a certain color; which has
512 PRE-CAMBEIAN ROCKS OF NORTH AMERICA. (BULL. 86.

been thought to be characteristic of the period. At other times the 

abundance of volcanic material has been the reason for the reference. 

Again, quartzites from the Appalachians to the Black hills have been 

correlated on no other ground than lithological likeness, as though 

thick sandstone formations which subsequently have been cemented to 

quartzites have been produced but once in the history of the world. 

To some geologists the degree of crystallization has been the controlling fact. In other cases the occurrence of some mineral or association of minerals has been the ground upon which the reference of the 

containing formation is made to some specific period. This has gone 

so far at times as to lead to the conclusion that a single rare mineral, 

such as chondrodite, is proof of the pre-Cambrian age of the containing formation.

 As a natural result of work of this kind, rocks of a certain lithological 

character or degree of crystallization, or containing certain constituents, 

have been called Arvonian, Huronian, Norian, Laurentian, as the case 

may be, which have afterwards proved to be high in the Paleozoic. 

Other series, which are now known to be pre-Cambrian, have been 

called Triassic, because of a prevailing red hue.

Any of the above characteristics may be a valuable guide in a given 

district, or with qualifying and guiding facts of a different character 

in a region; but it is their use in an indiscriminate manner on the 

assumption that rocks of a given time are every where alike that is protested against. When it is everywhere recognized that, considering 

the continent as a whole, age is no guide to the chemical or mineral 

composition, texture, color, degree of crystallization, or any other property of a formation, or vice versa, we shall be on the way to use the 

properties of rocks in districts and regions as guides to age. For the 

most part this principle has been recognized, if not practically, at least 

theoretically; but at one point this is less true than with the others. 

Degree of crystallization, because often so useful in a district, has been 

used by many as a general guide in correlation, although the elder 

Hitchcock, Eogers, Adams, and others gave early warning against 

such practices. It can not be too strongly insisted upon that contact 

action of great masses of eruptive rocks and dynamic action accompanying this, or dynamic action without accompanying volcanic activity, are prime and perhaps the chief causes in the majority of cases of 

the production of crystallization, not age and depth of burying, although 

these may be contributory causes and at times the predominant ones. 

A stratum which is strongly conglomeratic at the axis of a fold, within 

a short distance upon the legs may have become so completely crystalline as to obliterate every trace of original fragmental character, 

because of the movement of the particles over each other, as for instance, 

in the Cambrian at Hoosac mountain. In strong contrast to this may 

be mentioned the occurrence of quartzites in the lower part of the 

Upper Huronian of lake Superior, which show no evidence whatever
VANHISE.] DISCUSSIONS OF PEINCIPLES. 513

of dynamic action, the particles of quartz not even being arranged with 

their longer axes in the same direction, and the induration being wholly 

due to the process of renewed growth and cementation. Yet this and 

the adjacent rocks have been buried under the entire thickness of the 

Upper Huroniau and the Keweenawan series many thousands of feet 

and subjected to a pressure beyond the crushing strength of any rock, 

a condition in which they must have been latently plastic. Eocks as 

late as Devonian in the Appalachians have become so completely crystalline that not one vestige of the original fragmental material remains. 

Contrasting with this occurrence are the Chuar, Grand Canyon, and 

Keweenaw series, all wholly unaltered, yet pre-Cambrian.

No one would think of maintaining that in post-Cambrian time a rock 

of a certain composition is of a definite age; neither would any one 

think of referring a rock to the Devonian, Silurian, or Cambrian upon 

the degree of its crystallization. To suppose that the plane of the basal 

Cambrian is a magic one, below which new conditions of sedimentation 

prevailed and an entirely different set of principles apply in stratigraphy, is to assume a revolution in the conditions of the world at this 

time for which there is not one particle of warrant.. Those who believe 

in evolution must believe that for eras of time before the Cambrian 

there were cycles of deposition of the various classes of sedimentary 

rocks and the slow evolution of life to the high degree of perfection 

and the great variety of types including all important branches except 

the vertebrates found in the Olenellus fauna.

It may be said that the foregoing applies equally well to the separation of the Algonkian and Archean. Revolutionary methods can not 

be applied here more than elsewhere. To this it can only be said that 

this plane is the most remote and difficult to define of any. It may be 

that it is wrongly defined. Without question it Avill in the future be 

much more accurately defined. Eocks now placed in the Archean will 

be found to be Algonkian, just as series are being found to be Cambrian, Silurian, or Devonian in the Appalachians which have commonly 

been regarded as Huronian or Laurentian. While the distinctions 

made may not be complete, they are based upon the knowledge available, are not dogmatic, and do not, it appears to the writer, contradict 

the laws of geology. The law of uniformity, if rightly understood, does 

not imply that the causes now at work have always had the same relative value. When the laws of geologic forces are fully comprehended, 

it will be found that each is not absolutely uniform in power, but that 

each involves variables. These variables may be so small that the 

cumulative change in the effect in any case may not be discoverable in 

an epoch or even in a period; but that the amount of this effect perceptibly changed in eras, can not be doubted. A standard clock if 

observed for a day may seem to run with an invariable and correct 

rate, but if observed long enough it is found to lose or gain, and this 

not regularly. The law of its variation may finally be partly ascerBull. 86 33
514 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

tained, but usually it is too complex to be fully covered by a formula. 

Just so each geological force when more accurately known will be found 

to involve an irregular rate of change. The increment in an individual 

case for a certain length of time may be added or substracted, but it is 

not probable in any case that the addition or substraction will fully 

cover the real law, although this maybe a second approximation to the 

truth as the so-called law of uniformity was a first approximation. If 

we go far enough back a geological force may have been multiplied or 

divided by two or three or a larger number. Igneous rocks are now a 

far less abundant geological product than are sedimentary rocks. 

That these relations are true for all past time can no more be assumed 

than it can that organic and mechanical sediments have the same 

relative volume for the pre-Cambrian that they have for the Cretaceous or Tertiary. If the generally accepted hypothesis as to the origin 

of the globe represents the facts, in all probability rocks of igneous 

origin must become relatively more important in very ancient times. 

If we but go back far enough they may become predominant; and in 

still earlier time for continental areas they may be the only rocks.

The problem then of the stratigraphy of the pre-Cambrian elastics is 

a problem to be treated precisely as that of the Paleozoic. It is, upon 

the whole, a more difficult problem; for, while in any particular locality 

it can not be premised from the degree of crystallization that the rocks 

are pre-Cambrian or post-Cambrian; taking the world as a whole, the 

rocks become more crystalline in passing to lower series; so that it 

is to be expected and is the fact that a greater proportion of pre-Cambriaii rocks than of the Paleozoic are highly crystalline. This, however, is not the most serious difficulty with which pre-Cambrian stratigraphy has to contend; it is the sparseness of the remains of life in 

definitely recognizable forms. It has been seen that a beginning of a 

pre-Cambrian fauna has already been found, and when it is remembered 

how rapidly definite paleontological knowledge has extended downward in the past decade it may be reasonably hoped that before long 

assistance will be derived from paleontology in the classification of the 

pre-Cambrian rocks, but it can not be expected that fossils will ever be 

so important and controlling a guide as in the post-Cambrian; for 

probably the farther we go back from the Cambrian the sparser and 

sparser will the recognizable life-remains become.

As a result of the average greater crystalline character of the preCambrian rocks, and the frequency in them of secondary structures, 

the principles of. working out stratigraphy in regions in which cleavage foliation occurs with partial or total obliteration of stratification 

are of the utmost importance. The failure, to clearly recognize and 

apply these principles has left the crystalline Cambrian and postCambrian series of the Appalachians in a state of confusion for many 

years. Within the last decade, by a recognition and a close application of them a new start has been made in the study of this difficult 

region.
VANHISB.] DISCUSSIONS OF PRINCIPLES. 515

 That it will not do to regard slaty cleavage or foliation as bedding 

has long been recognized, although it has often occurred that in regions in which this has been distinctly stated it has also been said that 

bedding and cleavage do correspond without any evidence of such correspondence being given. If tangential thrust be assumed as the cause 

of foliation, unless the resultant folding be close, bedding and cleavage 

will usually not correspond for any considerable area 5 for cleavage and 

foliation have a tendency to develop transverse to the lines of pressure, 

while bedding is initially in the lines of pressure. In the closely folded 

series in which it may be said that resultant foliation and sedimentation 

correspond throughout, the use of the term bedding ought to be dropped, 

as there is no longer a basis upon which to estimate thickness, because 

in this case there must have been such an amount of movement of the 

particles within the beds over each other as to render it doubtful if 

bedding does still exist.

By the foregoing it is not meant to imply that the foliation, of thoroughly crystalline rocks may not widely correspond with bedding, but 

only that this is not usually the case when tangential thrust is the cause 

of the foliation. However, Smyth (H. L.) has discovered when there is 

an alternation of beds of different degrees of inassiveness that these 

often control the movements of accommodation during the folding of 

the series, and that the slipping of the particles over each other parallel to the bedding develops schistose structure along the same 

planes. It is not impossible that deeply buried beds may become 

thoroughly crystalline, with foliation and bedding parallel when superincumbent pressure and metasomatic changes are the predominant 

forces. A sufficient degree of heat for recrystallization may be engendered by very deep burying or by laccolitic intrusions. In such cases 

the structure of the recrystallized rock will naturally conform to the 

bedding, and it is probable that differences in the original characters 

of the layers will be preserved in the metamorphosed rock. A micaschist or gneiss thus derived from a shale or an arkose, now showing 

in its interior structure no evidence of clastic character, might be 

underlain by a quartzite which was produced by the cementation 

of a quartzose sandstone. The quartzite at the present time would 

reveal its detrital origin, while the mica-schist or gneiss might not. 

Some such explanation seems to fit the thick beds of mica-schist 

(the structures of which unmistakably correspond with bedding) 

which overlie the quartzites of the Penokee series of Michigan and 

Wisconsin. A crystalline series of the origin suggested, which subsequently reached the surface by denudation, might be folded, but not 

sufficiently to produce a new secondary structure, when the different 

bauds of different characters would truly represent sedimentary beds. 

Some such explanation seems to fit the gently folded thoroughly crystalline mica-schists and gneisses of the -Blue ridge west of Old fort, 

North Carolina. In the Adirondack®, where the schistose structure
5l6 TEE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL.86

and bedding of the Algonkian rocks appear to correspond, the great 

laccolites or batholites of gabbro are probably the chief cause of the 

metamorphism.

In crystalline series, when but one structure can be found, it is safe 

only to assume that it is foliation. Not only will it not do to use cleavage 

for working out structure, but an actual regular alternation of mineral 

constituents in schistose and gneissoid rocks can not be regarded as any 

evidence of sedimentation. The great series of regularly banded gneisses 

in which alternate zones of nearly pure quartz and feldspar and 

other zones in which the bisilicates are concentrated, if taken as due 

to sedimentation would result in the conclusion that the thickness of 

the beds in which these structures occur is incredibly great. In thoroughly schistose rocks it is manifest that the best and most reliable 

means upon which to base a conclusion as to strikes and dips is to find 

contacts between thick beds of rocks of a fundamentally different character, as a layer of quartzite, quartz-schist, or mica-schist, with limestone, or either of these with gneiss.

The clearest, briefest, and most comprehensive enunciation of the 

principles applicable to a formation in which are cleavage foliation and 

stratification foliation known to the writer is that of Dale and Pumpelly (see pp. 768-770), which is here quoted in substance, slight modifications being made to fit the change of setting:

I. Lamination in schist or limestone may be either stratification foliation or cleavage foliation, or both, or sometimes " false bedding." To establish conformability 

the conformability of the stratification foliations must be shown.

II. Stratification foliation is indicated by: (a) The course of minute but visible 

plications; (&) the course of the microscopic plications; (c) the general course of 

the quartz laminae whenever they can be clearly distinguished from those which lie 

in the cleavage planes.

This statement was made with reference to a particular district. It 

is of course wholly possible that some other substance should play the 

same role as quartz. In the application of these criteria it must be 

premised that the parting is not a second or third cleavage. If an 

earlier cleavage existed the criteria might give the direction of this 

first one rather than the bedding, which might have become obliterated 

at the time of the development of the first cleavage.

III. Cleavage foliation may consist of: (a) Planes produced by or coincident with 

the faulted limbs of the minute plications; (&) planes of fracture, resemblingjoints on a very minute scale, with or without faulting of the plications; (c) a cleavage approaching slaty cleavage in which the axes of all the particles have assumed 

either the direction of the cleavage or one forming a very acute angle to it, and 

where stratification foliation is no longer visible; (d) a secondary cleavage, resembling a minute jointing may occur.

IV. The degree and direction of the pitch of a fold are indicated by those of the 

axes of the minor plications on its sides.

V. The strike of the stratification foliation and cleavage foliation often differs in 

the same rock, and are then regarded as indicating a pitching fold.

VI. Such a correspondence exists between the stratification and cleavage foliations
VANBTSE.] DISCUSSIONS OP PRINCIPLES. 517

of the great folds and those of the minute plications that a very small specimen 

properly oriented gives, in .many cases, the key to the structure over a large portion 

of the side of a fold.

It is to be noted that the statement of these principles has been ininspired by a study of formations which have proved to be wholly Cambrian or post-Cambrian.

The principles of lithological correlation enunciated by Irving are as 

follows, except that series is here substituted for group and Algoukian 

for Huronian so as to make the terminology correspond with that here 

used:

Lithological characters are properly used in classification:

(1) To place adjacent formations in different series, on account of their lithological dissimilarities when such dissimilarities are plainly the result of great alteration 

in the lower one of the two formations, and are not contradicted by structural evidence, or, if used as confirmatory evidence only, when such dissimilarities are the 

result of original depositional conditions.

(2) To collect together in a single series adjacent formations because of lithological similarities when such similarities are used as confirmatory evidence only.

(3) To correlate series and formations of different parts of a single geological basin 

when such correlations are checked by stratigraphy, and particularly by observations made at numerous points between the successions correlated.

They are improperly used:

(1) To place adjacent formations in different series on account of lithological dissimilarities when such dissimilarities are merely the result of differences in original 

depositional conditions, and when such evidence of distinction is not confirmed by 

or is contradicted by structural and paleontological evidence.

(2) To collect in a single series adjacent formations because of lithological similarities when such similarities are not confirmed by or are contradicted by other evidence.

(3) To establish general correlations between the clastic series of different geological basins, except possibly when the gneissic and true crystalline-schist basement 

formation of one region is compared with the similar basement formation of another.

(4) To establish and determine any world-wide subdivisions of the noneruptive 

basement crystallines, i. e., those which underlie the clastic series here called Algonkian, at least until very much more definite evidence of the existence of such subdivisions be gathered than has hitherto been done.

In applying these principles it must not be forgotten that a bed of 

one character may thin out and disappear; may gradually change from 

a limestone to a shale, from a shale to a sandstone or conglomerate; 

and that sometimes the change may be abrupt, as perhaps upon the 

opposite sides of an axial ridge, one side of which faces toward the 

ocean and the other toward an interior sea. All formations, however 

widespread, terminate somewhere. A single formation of a certain 

lithological character can only be assumed to be the same bed in a district when it has been demonstrated to be persistent over a wide area. 

When several characteristic formations occur in a definite order in different parts of the same district the probability that they a,re of identical age is greater than with single beds found to be lithologically alike 

at separate points.
518 PRK-CAMBRIAN EOCKS OF NORTH AMERICA. IBULT..M.

The principles applicable to correlation by unconformities are given 

by Irving as follows:

The structural breaks called unconformities are properly used in classification:

(1) To mark the boundaries of the rock series of a given region.

(2) To aid in establishing correlations between the formations of different parts of 

a single geological basin.

(3) To aid in the establishment of correlations between the series of regions distantly removed from one another; but caution is needed in attempting such correlations in proportion as the distances between the regions compared grow greater.

They are improperly ignored:

(1) When the evidence they offer as to separateness is allowed to be overborne by 

anything but the most complete and weighty of paleontological evidence.

Irving's discussion leading to these principles shows that oftentimes 

unconformities are the most widespread and important of any of the 

means available to obtain starting planes for comparisons and that they 

have the place of first importance in making the major subdivisions for 

the origin of the pre-Oambrian clastic rocks. An erosion interval can 

only occur as a result of the raising of a district above the sea, a time 

of degradation, and then a depression below the sea; ,and if there is a 

true unconformity there must also have been an orographic movement 

and erosion long enough continued to truncate the folds. The erosion 

interval, if extended over a large area, implies a considerable time break; 

while the unconformity, if it is marked, can hardly be less than regional 

in extent. When the newer series is undisturbed, an. unconformity is 

one of the easiest of phenomena to detect, but more frequently than not 

among the pre-Oambrian rocks the older and newer series have again 

been folded, and this folding has oftentimes gone so far as to produce 

a cleavage or foliation, which cuts across both older and newer series 

and makes their most prominent structure in absolute conformity. 

Even if this degree of folding has not occurred and the process has not 

gone far enough to produce prominent secondary structures, the discordance in angle of inclination is more likely to be overlooked than when 

the series are in an undisturbed condition.

Since unconformities are so valuable in structural work, it is important that the principles be clearly recognized upon which they may be 

established in disturbed regions. This subject has been discussed at 

length by Irving, and from his paper the substance of much which follows is taken. An unconformity between series implies a difference in 

number of orographic movements with intervening erosion. This difference in number may be one or more than one. Even when the difference of orographic movements to which the series have been subjected 

is but one the time gap between the two must have been very considerable, and it may have been of vast duration. Consequently discordant 

series may differ in degree of consolidation, in the development of 

cleavage and foliation, and in their relations to eruptives. At the beginning of the deposition of the newer series basal conglomerates are 

often formed.
VAN msB.1 DISCUSSIONS OF PElNCIPLES. 519

Hence, as guiding phenomena in the discovery of unconformities, we 

have (1) ordinary discordance of bedding; (2) difference in the number 

of dynamic movements to which the series have been subjected; (3) discordance of bedding of upper series and foliation of lower ; (4) relations 

with eruptives; (5) difference in degree of crystallization; (6) basal conglomerates; (7) general field relations.

(1) In cases of ordinary discordance of bedding nothing need be said, 

except to state that unconformities should not be inferred from a single 

small contact where the apparent discordance may be due to false bedding or to local currents or very local minor disturbances. Also, the 

discordances caused by faulting may be mistaken for an unconformity 

if care is not taken. The amount of evidence for the unconformity 

should be sufficient to show a real discrepancy of bedding for a considerable area. Within a short distance the amount of discordance of 

bedding between two series may vary greatly. Frequently a dynamic 

movement mainly relieves itself along a comparatively narrow zone. 

This zone is one of uplift and consequently of great denudation. The 

adjacent plain may be little folded and not deeply eroded. When a 

new series is deposited upon this older series the former lies approximately parallel to the bedding of the older upon the plain, but along 

the zone of disturbance the first may lie directly athwart the bedding 

of the second.

(2) Difference in the number of dynamic movements to which the 

series have been subjected is often an important means of determining 

unconformities. In order that an unconformity shall occur the older 

series must have been subjected to at least one more orographic movement than the newer. In the most favorable case the older series has 

undergone two or more orographic movements while the newer series 

has undergone but a single one. When the lines of these movements 

are in the same direction and result in folding the only difference between the two series consists in steepness of inclinations; but in case 

the earlier movements were in a different direction from the last the 

older series will show a compound series of folds due to the resultant 

effect of the two or more movements, while the newer series will be 

simply folded. As a matter of course, in this discrimination, bedding 

must be used rather than foliation. Oftentimes it'will happen that the 

latest movement has produced a prominent cleavage or foliation which 

is common to both older and newer series; and under these circumstances the real discordance which may exist between the two series is 

particularly apt to be overlooked, and a district will be described as 

having a simple monoclinal structure, or one in which the series is reproduced by faulting, when evidence is at hand for two or more discordant series.

The orographic movements, instead of producing folding, may cause 

jointing or faulting, these results, as suggested by Willis, being perhaps due to insufficient load. These phenomena are, however, ser-
520 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 80.

viceable in discovering an unconformity, for the sets of faults or joints 

produced in the older series before the newer series was formed are not 

found in the latter. When there have been later orographic movements 

which have produced faults or joints in both series the unconformity 

will be shown by the presence in the older series of two sets of joints 

or faults in different directions, provided the directions of thrust were 

different, while the newer series will be affected by joints or faults only 

in a single direction. If the jointing or faulting is in the same direction in both the newer and -older movements they will not be of much 

service in detecting an unconformity, the only difference being their 

greater frequency in the older series.

When one of the orographic movements has resulted in folding and 

the other in faulting or jointing, the combination of phenomena are as 

easily used to detect an unconformity as when effects of the same kind 

are produced by both movements.

(3) Discordance of the bedding of an unfoliated series with the 

cleavage or foliation of an adjacent series may be taken as evidence of unconformity, if the former is such that it would take on 

cleavage or foliation as readily as the latter; for whatever the origin 

of the altered series the development of cleavage or foliation, which 

must have developed before the new series was deposited, required 

much time. An unconformity could not be inferred from the fact 

that a heavy formation of quartzite or of limestone cuts across the 

cleavage or foliation of an argillite or mica-schist, for clayey rocks 

very much more readily take on secondary structures. In the same 

series it often happens that more massive beds escape foliation, which 

may be prominently developed in other members. But if a formation with slaty or schistose structure is overlain by another formation without secondary structure which from its composition is as 

likely to take on foliation as the underlying formation, a discordance, 

while not demonstrated, is a probability for which other evidence 

should be sought.

(4) Eruptive rocks are often an important guide in determining 

structural discordances. These are valuable when the older series 

has passed through an epoch of eruptive activity before the newer 

series was deposited. In such cases bosses, contemporaneous or intrusive beds, volcanic fragmental material or dikes may occur in the 

older series, which nowhere are associated with the newer. It is possible, of course, that eruptives may penetrate the inferior members 

of a series and never reach the higher formations; but if it is found 

that the supposed inferior series is associated with abundant material 

of igneous origin which never passes beyond a certain plane, it is almost demonstrative evidence of the later age of the newer series. A 

notable instance of this is found in the Doe river section of eastern 

Tennessee, where the granitic rocks supposed to be older than the associated elastics are cut by very numerous schistose dikes which never
vANHieu.1 DISCUSSIONS OF PRINCIPLES. 521

intrude the latter. It might be reasonably inferred, if it were not for 

these dikes, that the granitic rock is an eruptive later than the elastics (although the absence of contact phenomena would be against this), 

but as the basic dikes are unquestionably intrusives of later age than 

the granites, and yet never cut the slates, this explanation can not 

possibly apply. Evidence of this kind is particularly decisive if the 

dikes are traced up to the plane of contact and have been found to be 

eroded or disintegrated, as is the case in the Stamford dike at Clarksburg mountain, Massachusetts, described by Pumpelly, which enabled this author to determine positively what had been believed before, that the granitoid gneiss is unconformably under the Cambrian 

quartzite.

(5) Closely connected with (3) and (4) is degree of crystallization as 

a guide to unconformities. It has been seen that crystalline character 

is often taken on in proportion as dynamic action occurs. When the 

folding, which has affected only the older series, has been severe, it as 

a whole will be more crystalline in character than the newer. Also the 

presence of igneous material is often a potent factor in the production 

of crystalline character. As, however, recrystallization is also produced 

by inetasornatic change, this criterion must be used with caution and 

as a cause to search for other evidences of an unconformity rather than 

alone as a basis upon which to infer an unconformity. But even difference of amount of metasomatic change, if the rocks are equally likely 

to be affected by these processes, may be evidence of difference in age. 

In determining degree of crystallization the modern petrographical 

methods serve one of their most useful purposes, since many rocks 

which in exposure or in hand-specimen appear to be about equally 

crystalline, are shown in thin section to be of a fundamentally different 

character. A completely crystalline rock sometimes can not be discriminated macroscopically from one which is merely indurated by 

cementation. For instance, a thoroughly crystalline granite and a 

recomposed rock built up of the debris of this granite, especially when 

the particles are in the form of individual minerals, rather than pebbles, present much the same appearance in mass, but a glance at sections of the two under the microscope shows the thoroughly crystalline 

interlocking character of the one and the clastic character of the other. 

Another case quite as marked is the discrimination between much foliated eruptive rocks which have passed over into fissile schists and 

ordinary argillaceous slates and gray wackes. In the latter class the particles of quartz and feldspar maybe seen with their oval forms as regular as the day in which they were deposited, while in the other case an 

entirely different appearance is presented.

(6) Basal conglomerates are one of the most important means of 

determining a plane of unconformity, but it must be clearly shown that 

the conglomerate is really a basal one. Conglomerates may occur in 

other positions than at basal horizons, and it will not do to assume
522 PRE-CAMBRIAtf ROCKS OF NORTH AMERICA. (miu..M.

that an unusually conglomeratic layer is basal. A conglomerate is 

likely to be basal when the major portion of the d6bris is derived from 

the immediately subjacent member j but even here the exception must be 

made that in case this subjacent member is a surface igneous rock the 

presence of the conglomerate is no evidence of a time break. If, however, the igneous formation is of such a character as does not originate 

except as a deep-seated rock, the fact that it is at surface and yields 

fragments to the overlying formation is evidence of a time gap. Also 

evidence of a break is just as decisive when the underlying rock has a 

foliation which has been produced prior to the deposition of the conglomerate. This may be determined from the fact that fragments 

broken from a foliated rock are apt to be longer in the direction of lamination, and when deposited in the overlying series they naturally lie 

with their foliation at an angle to that of the underlying series. It 

matters not whether the foliated rock of the inferior series be of sedimentary or of igneous origin. If sedimentary, a long time has been 

required to obliterate evidence of its fraginental character; if igneous, 

its foliation shows the effect.of long-acting forces. While basal conglomerates are often found they are also often absent where other evidence shows that there are discordant relations between two series. 

This absence is explained, at least in some cases, by Pumpelly's disintegration theory, the encroaching shore line finding a set of disintegrated rocks in which the mass is ready to yield particles of the constituent minerals rather than pebbles.

(7) General field relations are often sufficient to establish discordant 

relations between series when all other lines of evidence are lacking. 

When in a region immense stretches of rocks of one series are always 

found in an undisturbed condition, while an adjacent series is always 

disturbed, discordant relations may be inferred. This is particularly 

evident when the horizontal series fills bays in the older rocks, or is 

found as inliers surrounded by the other rocks. Again, the general 

field relations may establish an unconformity even if both series are 

disturbed. One case of this is the occurrence of a uniform belt of 

stratified rocks which, perhaps with a monoclinal structure and a 

somewhat uniform strike and dip, runs for great distances, the rocks 

of the adjacent unconformable series being here of one kind and there 

of another kind. The evidence for the unconformity in this case is 

still further emphasized if the lower series, instead of having a simple 

structure, is folded in a complex manner. General field relations may 

betray unconformity even when the newer series has been folded in a 

more complex manner, as, for instance, having been subjected to two 

orographic movements, the first of which placed it in a monoclinal 

attitude, and the second of which, at right angles to this first force, 

gave it a fluted structure. The lower series, instead of having this 

regular structure, being subjected to still earlier orographic movements, 

would be more irregular in its foldings and faultings, and the difference
VANHISE.] DISCUSSIONS OF PRINCIPLES. 523

in simplicity of structure of the two series would increase in proportion 

to the number and intensity of the earlier movements. However, as 

the movements which have affected the newer series increase, the difficulty of discovering discordances by general field relations is increased. 

These and other cases of general field relations which show unconformity 

may not appear to the observer while doing detailed work, since no 

contacts or other ordinary indication of unconformity is found, but 

strongly appear when the work is platted. To the mind of the writer 

general field relations of the kinds above cited are sometimes more decisive evidence of unconformity than almost any kind of local relations. When the local proofs above considered, combined with general 

field relations, unite as evidences of unconformity, as is generally the 

case if the worker takes advantage of all the facts available, the accumulated evidence for discordant relations, even in difficult and folded 

regions, is often decisive.

Unconformities have been frequently inferred on insufficient ground. 

This has sometimes resulted from regarding surface igneous rocks as 

sedimentary, and the basal conglomerate overlying such a formation as 

evidence of unconformity. More frequently the misinterpreted evidence 

of unconformity is a discordance in foliation; sometimes cited as occurring in actual contact, but at other times being a discordance only in 

the strike and dip of foliation at some distance. A contact discordance 

of foliation or bedding may occur as a result of faulting. The strikes 

and dips of banded and contorted schists and gneisses often vary so 

greatly within short intervals that a difference of this kind can not be 

taken as an indication of discordances. This error has occurred because 

it has been assumed that cleavage foliation accords with sedimentation. 

When it is practically, not theoretically, recognized that this structure 

is secondary may be produced in either sedimentary or igneous rocks 

and that it generally does not correspond over large areas with bedding, such evidence will cease to be used as indications of structural 

discordance.

The application of the foregoing principles demands tha,t in working 

out the structure of the crystalline formations the ground must be gone 

over in detail. No single section will be adequate to give a proper idea 

of the structure, nor will it do to consider that as a result of several or 

a dozen sections the structure of a large district may be worked out 

and the formations mapped, as has been too frequently done. Formations which outcrop in one section may not be exposed in another, or a 

formation between one section and the next may entirely change its 

character or disappear altogether. If the district is a difficult one the 

only safe way is to take advantage in the field of all available overground and underground facts, and to collect abundant material for 

supplementary office work. When only one structure is present and 

the character of that the least doubtful, it must not be assumed to be 

bedding. In regions in which the exposures are infrequent it may be
524 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

impossible to work out the structure of crystalline rock series which 

have a true detrital succession, but it is better for the present and the 

future that no structure be presented than a false one.

After working out the structure of one district in a geological basin, 

adjacent districts may be mapped much more rapidly. Under proper 

checks the lithological character of individual beds may be assumed to 

remain the same. Sets of like formation occurring in the same order 

may be assumed to be the same group of formations. And perhaps 

most useful of all are discordant relations between series. In correlations from region to region, without the assistance of paleontology it 

will probably not be possible to carry the analogy further than series; 

and in far distant regions even the general lithological likeness and 

similarity of position of series is not sufficient warrant for placing them 

opposite each other in the time column.

If the foregoing principles are true, it is plain that in working out the 

structure of a new region local names should be applied to the formations and series. When the time comes that fuller knowledge enables 

them to be safely correlated with the series to which classical names 

have been applied, this may be done, and the local names will not be less 

serviceable to designate particular parts of these general series.

The area in North America in which detailed mapping has been done 

with a resultant proper understanding of the structural relations of the 

pre-Cainbrian is surprisingly small. Scarcely a crystalline area on the 

continent has escaped the rapid geologist who has passed over a region 

and upon a few facts of uncertain value publishes structural conclusions which are not to be verified by future work. The districts carefully studied include the original Huronian of lake Huron, several 

small areas about Ottawa and between the Ottawa river and lake Ontario, a few small areas about the lake Superior region, a small part of 

western Massachusetts and a part of Maryland. Even in these districts 

the work at many points is rather old and to a certain extent unsatisfactory. Before reliable maps can be obtained this old work must be 

thoroughly revised in the light of the recent advances in the methods 

of study of the crystalline rocks. By this it is not implied that the 

more general work done is not of superlative value and of necessity 

must precede the more accurate accounts. A beginning has been made 

in American pre-Cambrian stratigraphy, but the great *mass of work 

remains for the future. .

RESULTS IN AMERICA AND EUROPE COMPARED.

This volume has already become too long to attempt to make a detailed comparison between America and Europe as to the results reached 

in pre-Cambrian stratigraphy. Also, I am wholly unfamiliar with European ground and am but imperfectly acquainted with the literature; 

hence I would not be warranted in making the attempt, even if space 

permitted. It may, however, be well, without giving any detailed facts
VANHISB.] DISCUSSIONS OF PKINCIPLES. 525

or reviews of literature, to mention the opinions which appear to be 

prevalent in reference to the pre-Cambriau of Europe.

In the first place, it is not universally held that in Europe there are 

pre-Cambrian elastics. It is probable that this difference of opinion 

results in part because it is not agreed as to the lower limit of the Cambrian. If this could be settled it would be comparatively easy to decide 

as to the existence of pre-Cambrian sedimentaries.

Nowhere has there been in the past a wider difference of opinion on 

this question than in Great Britain, but now the consensus of opinion 

appears to be that pre-Cambrian elastics, either water-deposited or 

volcanic, or both, occur at various places. The officers of the official 

survey have, until very recently, denied that such rocks occur 5 but the 

Director-General states, in a late paper, that in western Scotland, associated with the fundamental gneiss, are small areas of schist and 

limestones which are possibly sedimentary; that within the complex of 

rocks in Scotland, for which the term Dalradiari is proposed, there are 

probably pre-Cambrian elastics both of sedimentary and volcanic origin, and that Callaway is correct as to the pre-Cambrian age of the 

Uriconian volcauics. Still more recently it has been announced that 

the Torridon sandstone, 8,000 or 10,000 feet thick, which contains 

traces of annelids and other obscure organic remains, lies unconformably below theOlenellus Cambrian and must therefore be classed as preCambrian.

The head of the official survey of France, Michel-L6vy, states that 

in the pre-Cambrian are placed only those rocks which are completely 

crystalline and which antedate all the clastic series. The Cambrian is 

delimited below by the appearance of the first layers, which are incontestably clastic. It passes insensibly into the crystalline rocks regarded as pre-Cambrian. The Cambrian is delimited above by the 

overlying accordant or discordant strata-bearing fossils. The rocks 

placed in the Cambrian are for the most part nonfossiliferous, and, 

while clastic as a whole, are locally much altered by contact action and 

are more crystalline than the later formations. The foregoing positions 

are very different from those held by Barrois, another of the official 

geologists. This author holds that in France there is at least one 

series of pre-Cambrian rocks of clastic origin to which he has applied 

the term Huronian.

In Germany there is a radical difference of opinion between the leading geologists as to whether pre-Cambrian elastics exist, although a 

large majority maintains that belonging here are the Obermittweida 

conglomerate and similar rocks in other localities. Others hold that 

these rocks are in folded parts of the Cambrian or post-Cambrian. The 

commonly accepted classification of the pre-Cambrian rocks, according 

to Lossen, is as follows: (1) TJrgneiss or fundamental gneiss, which in 

places is rather a granite than a gneiss. Toward the top, the formation takes in beds of limestone, quartzite, and ainphibolite, generally,
526 PRE-CAMBRIAN ROCKS OF NORTH AMERICA. [BULL. 86.

however, without any vestige of clastic character. Above the Urgneiss follows (2) the Urglimnierschiefer, which passes into (3) the Urthonschiefer or Phyllit, and this contains younger gneiss formations. 

This classification has a structural basis to a certain degree, but seems 

to be primarily lithological. Credner, in the last (seventh) edition of 

his Elemente der Geologic, places the TJrgneiss as the equivalent 

of the Laurentian and the Urschiefer, including here the Urglimmerschiefer and Urthonscheifer as the equivalent of the Huronian of 

North America.

In Norway the director of the official survey, Dr. Eeusch, considers 

that it has been shown that there are in that country pre-Cainbrian 

elastics which are overlapped by the Cambrian. De Geer maintains 

that there are pre-Oambrian rocks in Sweden which are unconformably 

below the Cambrian. Eeusch is inclined to exclude these rocks from 

the Archean, the latter being restricted to the fundamental complex. 

If these results be accepted it follows that in Scandinavia there are 

rocks which take a position represented in America by the Algonkian.

The inclination to limit the term Archean to the fundamental complex is rather widespread in Europe, without reference to whether preCambrian elastics exist or not. Many of those who hold that pre-Cambrian elastics occur are disposed to give them distinctive names. As 

in America, no structural methods have been applied to the fundamental complex.

Eigidly defining the Archean to cover the basal crystalline complex 

and excluding from it all clastic rocks, we have in England, France, 

Germany, and Scandinavia equivalents of the Algonkian of America, 

if those geologists are right who maintain the pre-Cambrian character 

of the clastic rocks mentioned.

No attempt has been made, except in Great Britain, to subdivide into 

series the rocks equivalent to the Algonkian. The review of the facts 

in America has led to the conclusion that it is not practicable to make 

correlations over the whole continent of a more definite nature than 

Algonkian and Archean. If this be true, it is evident that correlations 

can not be more definitely made between European and American rocks. 

The application of such American terms as Huronian and Keweenawan 

to European series is wholly unwarranted.

If the suggestion be correct that the Archean is of a different character from any succeeding formation and has a continental extent in 

America, it may be safe to regard the fundamental complex of Europe 

as its equivalent. If this be done and Cambrian be delimited below 

by the Olenellus fauna, it would be safe to say that the intervening 

series of rocks occupy some position in the great Algonkian system. 

But any given series of the Algonkian of Europe can not safely be 

placed opposite a definite series in this country until there shall be 

found paleontological evidence for so doing.

Even if the Cambrian in Europe were rigidly delimited below by the
VANHISE.] DISCUSSIONS OF PRINCIPLES. 527

Olenellus fauna and all doubtfal series barren of fossils were regarded 

as pre-Cambrian, it would still be true tha.t the rocks thus referred to 

the Algonkian system would be insignificant in amount and extent as 

compared with the great areas and volumes here included in America. 

It would also be true that the structural work upon such series has not 

progressed so far. This is probably in large measure due to the nonoccurrence of such volumes of Algonkiarf rocks in Europe as exist in 

America; but it is also due in part to the fact that in that portion of 

Europe which has been most closely studied there have been since 

Cambrian time repeated powerful dynamic movements and periods of 

great eruptive activity. The conditions are much the same as in the 

eastern United States, where a study of pre-Cambrian stratigraphy has 

barely begun. In the interior of the American continent the conditions 

have been far more favorable for a structural study of the pre-Cambrian rocks.

NOTES.

1 Observations on the Geology of the United States Explanatory of a Geological 

Map, Wm. Maclure. Trans. Am. Phil. Soc., vol. vi, pp. 411-428. With a map.

2 Geological Text-Book, for Aiding the Study of North American Geology, Amos 

Eaton. Albany, New York, and Troy, 1832, 2d edition, pp. 134.

3 American Geology, Ebenezer Emmous. Albany, 1855, pp. 194, 251, with an atlas 

and a geological map of the United States.

 "Esquisse Ge"ologique dn Canada, a 1'Exposition Universelle de Paris, W. E. Logan 

and T. Sterry Hunt. Paris, 1855, pp. 100. With a geological map. From translation by Mr. Robert Stein.

5 Manual of Geology, James D. Dana. Philadelphia, 1863,1st ed., pp. 798. With 

a map.

6 On the Occurrence of Organic Remains in the Laurentian Rocks of Canada, Sir 

W. E. Logan. Qnarfc. Jour. Geol. Soc., London, 1865, vol. xxi, pp. 45-50.

7 Esquisse Ge"ologique du Canada, suivie d'un Catalogue Descriptif de la Collection 

de Cartes et Coupes Ge'ologiques, Livres Imprimis, Roches, Fossiles et Mine"raux 

Economiques envoye"e a 1'Exposition Universelle de 1867, T. Sterry Hunt. Paris, 

1867, pp. 72." From translation by Mr. Robert Stein.

8 Notice of the address of Prof. T. Sterry Hunt before the American Association at 

Indianapolis, James D. Dana. Am. Jour. Sci., 3rd ser., vol. HI, 1872, pp. 86-93; vol. 

iv, pp. 97-105.

9 Manual of Geology, James D. Dana. New York, 1876, 2d ed., pp. 828. With a 

map.

10 Systematic Geology, Clarence King. U. S. Geol. Exploration of the Fortieth 

Parallel, vol. i, pp. 803, 12 analytical geological maps, and accompanied by a geological and topographical atlas.

11 Report of Observations on the Stratigraphy of the Quebec Group, and the Older 

Crystalline Rocks of Canada, A. R. C. Selwyn. Rept. of Prog. Geol. Survey of Canada for 1877-'78, pp. 1-15A.

12 Summary Report of the Operations of the Geological Corps to December, 1880, A. 

R. C. Selwyn. Rept. of Prog. Geol. and Nat. Hist. Survey of Canada for the year

1879-;80, pp. 1-9.

13 Notes on the Geology of the Southeastern Portion of the Province of Quebec, A. 

R. C. Selwyn. Rept. of Prog. Geol. and Nat. Hist. Survey of Canada for the years

1880-'81-'82, pp. 1-7A.
528 PRE-CAMBRIAN ROCKS OF NORTH AMERICA.

14 Descriptive Sketch of the Physical Geography and Geology of the Dominion Oj, 

Canada, A. R. C. Sehvyn and G. M. Dawson, pp. 55. ;

15 The Azoic System and its Proposed Subdivisions, J. D. Whitney and M. E. Wads-;, worth. Bull. Mus. Conip. Zool., Harvard Coll., whole series, vol. vn (Geological* 

series, vol. i), pp. 565.

16 The Anorthosite Rocks of Canada, Frank D. Adams. Rept. of the British Assn.' 

for the Adv. of Sci., 56th meeting, 1886, pp. 666-667.

17 On the Eozoic and Palaeozoic "Rocks of the Atlantic Coast of Canada, in Comparison with those of Western Europe and of the Interior of America, Sir J. William 

Dawson. Quart. Jour. Geol. Soc., London, vol. XLIV, 1888, pp. 797-817 j see, also, Proc. 

of the Geol. Soc., London, vol. XLV, 1889, p. 80. i

18 On the Classification of the Early Cambrian and Pre-Cainbrian Formations,; 

Roland Duer Irving. 7th Ann. Rept. U. S. Geol. Survey, 1885-;86, pp. 365-454. With 

22 plates and maps.

w Les Schistes Cristallins, Dr. T. Sterry Hunt. International Geol. Cong., London,, 

1888, pp. 1-15. From translation by Mr. Robert Stein. See, also, On the Geology :' 

Canada. Proc. Am. Assoc. Adv. Sci., 1849,2d meeting, pp. 325-334. On the Taconic System. Ibid., 1850,4th meeting, pp. 202-204. On some of the Crystalline Limestones o" 

North Ainerfca. Am. Jour. Sci., 2d ser., vol. xvm, 1854, pp. 193-200. On the Taconic 

System of Dr. Emmons. Ibid., vol. xxxii, 1861, pp. 427-430. On some Points ir 

American Geology. Ibid., vol. xxxi, 1861, pp. 392-414. On the Chemical and Mineralogical Relations of Metamorphic Rocks. Can. Nat. and Geol., vol. vin., 1863, pp. 

195-208. On the Mineralogy of Certain Organic Remains from the Laurentian Rocks 

of Canada. Quart. Jour. Geol. Soc., London, vol. xxi, 1865, pp. 67-71. On the 

Geology and Mineralogy of the Laurentian Limestones. Rept. Prog. Geol. Survey of 

Canada for the Years 1863-'66, pp. 181-229. On the Laurentian Limestones and 

their Mineralogy. Proc. Am. Assoc. Adv. Sci., 1866, 15th meeting, pp. 54-57. On 

Laurentian Rocks in Eastern Massachusetts. Am. Jour. Sci., 2d ser., vol. XLIX, 1870, 

pp. 75-78,398. On Norite or Labradorite Rock. Ibid., pp. 180-186. Notes on Granitic Rocks. Ibid., 3d ser., vol. i, 1871, pp. 82-89,182-185; vol. in, pp. 115-125. Geognosy of the Appalachians and the Origin of Crystalline Rocks. Proc. Am. Assoc. 

Adv. Sci., 1871, 20th meeting, pp. 1-59. Remarks on the late Criticisms of Prof. 

Dana. Am. Jour. Sci., 3d ser., vol. iv, 1872, pp. 41-52. Geology of Southern New 

Brunswick. Proc. Am. Assoc. Adv. Sci., 1874, 22d meeting, pp. 116-117. Breaks iu 

the American Paleozoic Series. Ibid., pp. 117-119. On the History of the Crystalline Statified Rocks. Ibid., 1877, 25th meeting, pp. 205-208. The Older Rocks of 

Western North America. Ibid., 1878, 26th meeting, pp. 265-266. "Azoic" Rocks, Part 

1. Second Geol. Survey of Penn., vol. E, pp. 253. On the Geology of the Eozoic Rocks 

of North America. Proc.'Bost. Soc. Nat. Hist., vol. xix, pp. 275-279 (abstract). The 

Pre-Cambrian Rocks of the British Islands. Ibid., vol. xx, 1878-1880, pp. 140-141. 

The History of some Pre-Cambrian Rocks in America and Europe. Proc. Am. Assoc. 

Adv. Sci., 28th meeting, 1880, pp. 279-296. Quart. Jour. Geol. Soc., London, vol. 

' xxxvm, 1881, pp. 4-5, proceedings. The Taconic System in Geology. Am. Nat., vol. 

xv, pp. 494-496. The Geology of Lake Superior. Science, vol. I, p. 218. Notes on 

Prof. Hall's address. Proc. Am. Assoc. Adv. Sci., 31st meeting, Part 1, pp. 69-71. A 

Historical Account of the Taconic Question in Geology, with a Discussion of the 

Relations of the Taconiau Series to the Older Crystalline and the Cambrian Rocks. 

Proc. and Trans. of the Royal Soc. of Canada for the years 1882 and 1883, vol. I, sec. 

4,1883, pp. 217-270; vol. n, sec. 4,1884, pp. 125-157. The Genesis of the Crystalline ' 

Rocks. Am. Nat., vol. xvm, 1884, pp. 605-607. The Pre-Cambrian Rocks of the 

Alps. Proc. Am. Assoc. Adv. Sci., 1883, 32d meeting, pp. 239-242. The Eozoic Rocks 

of North America. Geol. Mag., njew series, Decade III, vol. i, 1884, pp. 506-510, Mineral Physiology and Physiography. Boston, 1886; 710 pages. The Genetic History 

of Crystalline Rocks. Trans. Royal Soc. Canada, vol. iv, sec. 3, 1886, pp. 7-37. Gastaldi on Italian Geology and the Crystalline Rocks. Geol. Mag., new series, Decade
;A»IUBB.| DISCUSSIONS OF PRINCIPLES. 529

III, vol. IV, 1887, pp. 531-540. The Geological History of the Quebec Grotip. Am. 

3eol., vol. v, pp. 212-225.

20 The Huronian System of Canada, Robert Bell. Trans. Royal Soc. Canada, sec. 

f, vol. vi, 1888, pp. 3-13.

51 Geology of Ontario, with special reference to economic minerals, Robert Bell. 

Report of the Royal Commission on the Mineral Resources of Ontario: Toronto, 

1890, pp. 1-70.

22 The Fauna of the Lower Cambrian, or Olenellus Zone, C. D. Walcott. 10th Ann. 

Rept. U. S. Geol. Survey, 1888-'89, pp. 509-760. With plates and maps.

23 On subdivisions in Arohean Hisiory, James D. Dana: Am. Jour. Sci., 3rd ser., 

1892, vol. xmi, pp. 455-462.

Bull 86 34

INDEX.

Page. 

A.

Adams (F. D.), on the Eastern Townships ___._.......... -- -- . 225-226

on pro-Cambrian succession........ 457-458

Adams (C.B.), on Vermont..........355,356,385

on New England ... .... .. 382 

on Azoic... .--- .- -- 470

on origin of Archean................ 479

on lithological correlation.......... 512

Adirondacks, Pumpelly, Walcott, Van

Hise on............... ----- 398

Williams and Van Hise on.......... 398-399

Norianof ............ .. . . 413

Algonkianof ........... - 413-414,508

Archean of....... .. 413-414

Agassiz, on lake Superior........-.. .. 75,196

on lake Superior sands tone....... 86,158,160

Agnotozoic, proposal of, bylrving.,147,148,461,

462,475,491,493

Aikin, on Maryland ..................... 410

Akeley lake, Minnesota, Bayley on..... 155-156

Akerly, on New York ................... 386

on Primitive.......... .. ....... 470

Alabama, literature of.................. 426-427

Alexander, on Maryland._... ._. 410 

on Primitive.__........._.___ 470

Algor, on Nova Scotia................... 239

Algonkian and Archean, unconformity between, at lake Superior .. 174-178 

Algonkian, unconf ormably below Ton to 331 

fossils of. . ...... . . 469

Walcott on........................... 469

proposal of, by U. S. Geological Siirvey .......... .. ..'I... 475-493

relations to Archean.............482-487,513

life of,. ............................l,.. 491-492

necessity of.._................._ 491-493

relations to Huronian. _..... __ 493

delimitations of.....,. ........... 493-496

unconf ormably above Archean..... 495

upper limit of ............__....... 495-496

correlation within................... 496-497

difficulties of stratigraphy .......... 496-497

sparseness of fossils in.... ___.... 496-497

of original Laurentian......_.... 497-498

fossils of lake Superior ... ___ _ 499 

stratigraphy..... ............_.. 511-524

crystalline character of........._ 514

of Adirondacks.......... ......413-414,508

of America and Europe compared . 526-527 

of Antelope island .._.._...... 506

of Aqui mountains........____. 506

of Arizona........ ........ _ 331-332

Page. Algonkian Continued.

of Arizona, unconf ormably above

Archean......_................ 331

of Blackhills ........................ 503

of British Columbia............. .342,507-508

of California......................... 341

of Cape Breton ...................... 502-503

of Colorado ..__......__......_. 325-326

of Eastern Townships.. ...226,227,501-502 

of Eganrange .......... ......_ 506

of Europe.............. . .... 526

of Fremorit island _ .__ _. _ 506 

of Front range ......_....._._ 325,506

of Grand cany on....__...___ 507

of Hudson bay ...................... 500-501

of lake Superior, denned .......191,192,194,

 499-500 

of lake Superior, unconformably

above Archean....... ....._ 500

of lake Superior, unconformities

within............................ 500

of Medicine Bow range ............. 277,504

of middle Atlantic states ........... 413-415

of Missouri .......................... 265,504

of Montana.......................... ,286

of Montana, unconformably above

Archean........ ....... 505

of Nevada ........................... 307-308

of Newfoundland .............___ 503

of Newfoundland, fossils in .... _ 251

of Newfoundland, unconformity at

top of. ...... . . 251

of northern Canada .... ...... 218,501

of northern New Mexico ._.__.. 325 

of Nova Scotia ......_.._.._ 502

of original Hur onian .._ __. 498-499 

of Park range ............ 277

of Pinon range .. . .. 506 

of Pogonip range .... .... ..... 506

of Promontory ridge ...... ._.. 506

of Quartzite mountains..__325,326,507 

of Schellcreek .....___...__ 506

of southern Atlantic states _. _. 428-429 

of southern New Brunswick.... _ 502

of southwestern Montana .. _ _ 504-505 

of Texas.........................__ 269,504

of Uinta mountains................. 297,505

of Wasatch mountains._.._.... 299,505

stratigraphy, paleontology in...... 514

Animikie, proposal of, by Hunt...._ 59

 unconformably below lake Superior

sandstone,Hunt on.........._. 59

relations to Huronian, Hunt on.... 59

Selwynon.__.__.._........... 63

531
532 INDEX.

Page. 

Anlmlkle Continued.

McKellar on _.....___.._ 65

unconf ormably below Keweenawan,

McKellar on ..................... 65

unconformably above Huronian,

McKellar on ._...___...... 65

unconformably below Nipigon, Bell

on................................ 70,468

unconformably above Keewatln,

Alex. Winchellon............... 128

relations to Keweenawan....... _. 161

unconformably below Keweenawan.......... ....................... 161-162

relations toHuronian............... 168,169

character of..._.._________ 169 

relations to Keewatin.___.._.. 169 

unconformably above Vermilion series...............................-181,182

equivalent to Penokee series .. _. 187-189 

Hunt on.............................. 465

Bell on ............................... 468

use of....... ......... 472

Animikie district, iron ores of.... ..... -171,172

eruptives of.._._................ 173

succession in _.._......__ 187-189

Animikie formation, Bell on ........... 69-70

fossils, Selwynon................... 67,492

of lake Superior, Algonkian........ 499

Animikie series, Selwyn on _..... _. 62-63

Alex. Winchell on .._. _. _ _ 128 

Irving on.............................. 138-139

unconformity at base of ............ 176,179

unconformably above Kaministiquia .._.._.......-.-.-.....-. 182

relations to original Huronian...... 185-186

equivalents of....................... 187-189

fossilin.............................. 194

position of, Selwyn on............... 194

position of, N. H. Winchell on...... 194

Anorthosite in Laurentian..........._ 33

Antelope island range, Algonkian of... 506 

literature of......................... 295

Anticlinal structure of Archean ranges 490 

Antisell, on California.................. 333

Appalachian, Archean of................ 487

Aqui mountains, literature of.. _. _. 296 

Algonkian of.... . .... ........... 506

Archean, divisibility of, Irving on...... 142-143

proposal of, by Dana................ 394,473

unconformably below Silurian,

Dana on.......................... 447

Dana on.......... .. .....447-448,469-470

King on.............................. 448-451

Selwyn on.... .................... 453-454

Irving on..........................460,461,462

Bell on............................... 466

Walcott on........................... 469

areasof _ .................._ 475-476

character of......................... 475-478

use of term........................473,475,478

devoid of sedimentary rocks........ 477

origin of.............................. 478-484

relations to Algonkian _.__.482-487,518 

delimitations of............_...... 484^487

stratigraphy of...................... 487-490

includes Laureiitian ................ 488-490

unconformably below Algonkian .. 495

Archean Continued.

of Adirondacks...................... 413-414

of America and Eiu'ope compared.. 526 

of Arizona.......................... 330-332

of Arizona, unconformably below

Algonkian........................ 331

of Arizona and New Mexico, Powell

and Gilbert on....-........---.... 331

of California....................- . 341

of Canada (central), Lawson on.... 68

of Canada (northern), G. M. Dawson

on ................................ 217-218

of Colorado .......................... 324-325

of Europe.__.........._......... 526

of Grand canyon, unconformably

below Algonkian ....._..._.. 507

of lake Superior, Irving on ...._ 143-144

of lake Superior, character of...... 168

of lake Superior, defined.........191,192,194

of lake Superior, relations to eruptives... .......................... 192-193

of lake Superior, origin of.......... 198

of lake Superior, unconformably

below Algonkian..............174-178,500

of Massachusetts, unconformably

below Cambrian............_.. 371

of Medicine Bow range ......--. .. 277

of middle Atlantic states'........_ 413-415

of Montana .......................... 286

of Montana, unconformably below

Algonkian _.. .............. 505

of Nevada............................ 306,307

Of New Mexico...........---.324,325,330-332

of Park range.. ......... ....... 277

of southern Atlantic states ......... 427-429

of Texas.......__........ . .... 269

of Wasatch........................... 298-299

Archeozoic, Dana on life of..._..__ 469-470 

Archeozoic seon, Dana on............... 469

Arctic archipelago, Haughton on ...... 216

Arizona, literatureof................... 326,332

Archean of..... .. ............... 475,487

Arvonian, Whitney and Wadsworth on. 457 

Hunt on....-...-...-.- . .462-463,465,474

Astral ason, Dana on ._........-. ..... 469

Avalon peninsula, Murray on.......... 249-250

Howleyon............................ 250,251

Azoic, Whitney and Wadsworth on

absence of life in................ 455

C. B. Adams, Bell, Cook, Crosby. 

Dana, E. Emmons, Frazer, E. 

andC. H. Hitchcock, Kerr,H. D. 

Rogers, Safford, Wadsworth, 

and Whitney on......443-444,447,454-457,

466,467,470 

useof term.......................470,473-474

of lake Superior, Foster and Whitneyon ............ ............ 79-82

of lake Superior, Whitney on ...... 85

of lake Superior, character of...... 167

of Michigan, Wadsworth on........ 102

Azoic aeon, Dana on......_.......__ 469

B.

Back, on Southampton island........ 215

Baffin bay, McCulloch, Jameson, and

Koning on ....... -.-. .--,... 213,214
INDfiX. 533

Page.

Baffin land, Boas and Sutherland on... 215,217 

Bailey, on Maine ._.__._-.....---..-- - 231

on New Brunswick.... .229,230-231,231-233,

234-236 

on Caledonia mountains........ 233

on Coldbrook group. .. - 233 

on GrandMauan ...... .... 233

on Mascarene and Kingston series 233 

on pre-Camtorian of southern New

Brunswick....................... 237

Ball, on Sweetwater mountains........ 278

Baraboo quartzite, Percivalon.. 105 

J. H. Eaton on__... -- 107 

relations to Huronian... ........ 186-187

Barlow, relations of Huronian and Laurentian.._.._...._---_ 42,47

Barnes, onlake Superior ... ......... 75

Barrels, on France...................... 525

Bauerman, on British Columbia........ 338

Bayneld, on lake Superior.............. 51-52

onlake Superior sandstone.... . 157,158

onKeweenawan... ..... ....... 161

on the St. Lawrence river........... 218

Bayley, on Akeley lake, Minnesota..... 155-156

onKeweenawan .... .... 162

Becker, on California ................336-337,341

Bell, onLaurentian ..................... 31

on Nipissing Laurentian ........... 34

on Huronian....._..._...__...;...42,43-44

onlake Superior.................58,59,60-61

on lake Winnipeg................. 59,61

on country between Red river and

South Saskatchewan.. _.. 59 

on rocks from Moose river to lake

Superior......................... 61

proposal of Nipigon by .. ........ 61

on lake of the Woods ............... 62

on Huronian of lake Superior...... 68-70

on Hudson bay.............70,209,210,211,212

on lake Superior sandstone.... . 158

on lake Superior succession _. _ 163 

onKeweenawan_____..__ 162 

on relations of Huronian and Laurentian._.._._............ 174,177

on relations of Algonkian and Archean............................. 177,192

on country south of Hudson bay ... 209,210 

on Moose river and adjacent country............................... 211

on Huronian of Hudson bay ........ 212-213

on Laurentian of Hudson bay... _ 212-213 

on Labrador _...................... 217

on pre-Cambrian succession.... _. 460-468

Big Horn mountains, literature of..... 277-278

Blgsby, on Laurentian........_.__ 27

on Huronian.........____...... 35,39

on Transition formation.... _ _ 46

on lake Superior ............51,53-54,157,158

onlakeof the Woods.......____ 51,53

on Rainy lake _ ...____._ _ 54 

on lake Superior succession .. __ 165 

onlake Superior syncline......_ 196

Black hills of Dakota, literature of..... 257-260

Algonkian of..(__....._.......... 503

Black river falls series, Wisconsin, 105 

Daniel on equivalents of _____'. 190

Page. 

Blake, on Black hills.................... 259

on Front range.__ .. _. __ _ 314 

. on California ........................ 333,334

on origin of Archean.__......_ 479

Blandy, on Portage lake trap range ... 86 

Bloomsbury group, Bailey, Matthew,

andHartton..................... 230,231

Boas, on Baffin land...._._.._.... 217

Bonavista bay, Murray on.._........ 249

Bonney, on Huronian................... 41-42

Booth, on Delaware........._........ 412

on Primitive......................... 470

Boston, Shaler on rocks near.._..._ 364 

Bowman, on British Columbia ......... 339-340

Bradley,onTetonrange ........... .... 281

on Wasatch mountains............. 290

on Tennessee........................ 423

British Columbia, literature of......... 337-341

Algonkian of......................... 507-508

Britton, on New York................... 396,397

on New Jersey.__..___.._.... 402-403

on New Jersey gneiss .__........ 415

on Virginia and Tennessee ....._ 427

Broadhead,on Missouri ......_.._ 263

Brooks, on Copper-bearing series . __ 90-91 

on upper peninsula of Michigan .... 91-93

onlake Superior............._... 95-E6

proposal of Keweenawianby..._ 96 

on Huronian of Michigan ..........96-97,168

on the Menominee district.. _.... 115-116

on lake Superior sandstone.. _... 158 

onKeweenawan.___....._.__ ' 161

on lake Superior succession ........163,164,

165,166 

on lake Superior Laurentian.... 167,168,489

on iron ores of lake Superior....... 171,173

on unconformity at base of Marquette series....__. __ 175

on unconformity at base of Menominee series ....................... 175

on unconformity at base of Algonkian .............................^ 176

on unconformity within Huronian. 179,180 

on unconformity within Menominee series ....._............... 180,181

Brother ton, on northern Wisconsin ... 116 

Brown, on cape Breton ....._....._. 239

Buckley, on Texas _......_....._ 266

Burbank, on Massachusetts.........365-366,367

Burnetian series of Comstock.......269,474,504

Burt, onlake Superior..............._ 75,78

on lake Superior sandstone__ 158

C.

Caledonia mountains, Bailey and Ells

on ................................ 233

California, literature of................. 832-337

Callaway, on Uriconian.........__ 525

Cambrian, Selwyn on.........._.._ 451

of Massachusetts uncomformably 

above Archean.._..____ 371

useof term.........._..__...._ 475

Campbell, (J. B.), onlake Superior._ 73 

Campbell onNova Scotia............... 240

Campbell (J. L.), on Virginia........416,417,418

on Georgia..._ ....___..._ 426
534 INDEX.

Page. 

Campbell (H.D.),on Virginia...__.... 418

Canaan, Connecticut, Dana on.. ___. 379

Canada, northern, literature of _ __ 209-222

literature cited...................... 220-222

Algonkianof .._................... 501

Canada,eastern, literature of....233-247,252-255

Canadian literature of lake Superior... 51-72 

Canadian stratigraphy, Macfarlane on. 61-62 

Cape Ann, Shaleron._..._....._. 370

Cape Breton, literature of _.__ _ 239-244 

Laurentianof. ._ -..__._ .. 246,247 

Algonkianof......................... 502-503

Cape Granite, Murchison on..._.._ 215 

Carpenter, (F. R.), on Black hills ..._ 259 

Carpenter (W. L.), on Big Horn mountains.. .............................. 278

Cascade formation, Wadsworth on .... 102

Catlin,onpipestone quarries......__ 72

Chamberlin, on Wisconsin... 110,114-115,116-118 

on the Penokee district............. ill

on Copper-bearing series,,..._._ 139-140 

on junction between Eastern Sandstone and Keweenaw series ._ 140-142 

on lake Superior sandstone....._. 158,160

on lake Superior succession ........ 164

on Laurentian of lake Superior .... 168

on unconformity at base of Algonklan.... ......... .-........ ire

on lake Superior syncline .... __. 196

onLaurentian... __ . _... 489-490 

Channing, onHuronian._-..__.__. 36 

Chester (A. H.), on theMesabi and Vermilion ranges..........._.._ 123

Chester (F. D.), on Delaware....... 412-413,415

Chippewa quartzite, relations to Huronian.... --.-._.- ........... 186-187

Cleavage, Jukes on........ ...._... 252

relation to stratification............ 384,385,

386,515-517

Coastal group, Bailey and Matthew on. 232,

237,238 

unconformable with Coldbvook,

Bailey on......................... 235

Coldbrook, conformable with St. John

group, Bailey, and Matthew on. 231,232 

unconformable with Coastal, Bailey on__......._............_ 235

Bailey, Ells, Hartt, and Matthew 

on ................. .........230,231,232,233

Colorado, literature of.................. 308-324

Archeanof................... 324-325,477,487

Algonkianof.... ... ............ 325-326

Colorado range, King on,._...... 274-275,312

Comstock, on Texas..................267-268,269

onBurnetian series ..._........269,474,504

on Fernandian series............. 269,474,504

on Texian series..................269,474,504

on Wind River mountains .. _..... 279

on Quartzite mountains. _ __.. 320 

Conformity between lake Superior 

Huronian and Laurentian, Loganon. ...... ............ 55

of lake Superior Huronian and

Laurentian, Selwynon._.._ 62 

between Keewatin and Coutchiching, Lawson on ..__...._ 66

Page. 

Conformity Continued.

of Vermilion and Keewatin, N. H.

Winchell on...................... 129

of Laurentian and Huronian, Bell

on.............................209,210,211

of Coldbrook and St. John groups,

Bailey and Matthew on......... 231,232

Conkling, on Califoruia ................. 336

Connecticut, literature of............... 377,379

Conrad, on New York................... 387

Cook, on New Jersey.___._......400-401,402

on Azoic.__..___...__._._ 470 

Cope, on Sangre de Cristo mountains.. 313 

Copper district of lake Superior,

Wadsworth on................... 86-87

Copper-bearing rocks, Pumpelly on _ 97 

Copper-bearing series, unconformably below lake Superior s.andstone,Loganon ..._...__. 55-56 

unconformably above Huronian,

Loganon..._........._.... 55

unconformably above Laurentian,

' Macfarlane on.__ _......... 56-57

unconformably below lake Superior sandstone, Macfarlane on.. 56-57 

unconformably below lake Superior sandstone, Brooks and 

Pumpelly on..................... 90

Bell, Brooks, Chamberlin. Irving, 

Logan, Macfarlane, Marvine, 

Pumpelly,Sweet and Whittlesey 

on 53,56,56-67,61,90-91,93,94-95,106-107,114, 

134-139,139-140 

(See Cupriferous series.) 

(See also Keweenawan.)

Coppermine river, Richardson on ..._ 214 

Coppermine series..............._.._ 501

Cordilleras, literature of the ........... 272-342

literature of, cited .................. 342,347

Cornelius, on Virginia .........I........ 416

Correlation, lithological, Selwyn on.447,452-453 

lithologicaVIrvingon .......511-513,517-518

by unconformity ...........__..... 518-524

by unconformity, Irving on _.... 459-460

of lake Superior formation.. 183-195,198-199 

of Arizona and lake Superior series 331-332- 

withinAlgonkian................... 496-497

Cortlandt series, NewYork,Williams on 397 

Cotting, on Georgia..................... 425-426

Coutchiching, proposal of, by Lawson.. 65,474 

series, Lawson on................... 66,169

conformable with Keewatin, Lawson on _. .... ---,£,--- 66

unconformably below KeewSm.... 176

relations to Algonkian and Archeau 192,194 

Cozzens on Rhode Island.___ ........ 377

Cozzens, on Long island, New York.... 393

Credner, on the Upper peninsula of

Michigan...._................. 90

on unconformity within Huronian. 179 

on New York island....._____ 394

on Germany -... ............... 526

Crosby, on Black Hills.................. 259,261

on Massachusetts........ 366-367,367-368,370

on New England granites.._.._ 383 

on Azoic ___.. _.. ___ ____ 470
INDEX. 535

Page. 

Crystalline character of Algonldan.... 514

Cuuuiugliam, cm lake Superior......... 73

Cupi'iferous series of Duluth, N. H.

Wincheli on........................ 120-121

ol Minnesota, N. H. Wincheli on... 122 

SeeKeweenawan. And Copper-bearing

series.

Curreyon Great Smoky mountains, Tennessee..________.......... 422

D.

Dakota, quartzites of, White on........ 119

Haydenon.._-__............... 134

Dale, on mount Greylock, Massachusetts. .................................374-376,415

on Rhode Island.___._..._.... 377

on New Englanfl...........~ ~ 382,385

on Algonkian stratigraphy ......... 511

on cleavage and stratification..._ 516,517 

Dalradian, Geikie on .................... 525

Dana, on California..................... 332

on Canaan, Connecticut............. 379

on Great Barrington.Massachusetts 365,367 

on New England.............379,380,382,385

proposes Archeau _...... .. 394,473

on New York .....................394,395,415

on pre-Cambriansuccession ....443-444,447-

448,469-470 

on lithological correlation.......... 447

Daniel, on Black river falls, Wisconsin. 105 

Darton, indebtedness to ................ 17

on New Jersey granite ............ 401

Davis, on Montana ...................284,286,299

Dawson (G. M.), indebtedness to....... 17

onthelakeof the Woods........... 59-60

on lake Superior succession.... _ 165

on Laurentian of lake Superior.... 168

on Archean of northern Canada .... 217,218

on British Columbia .337,338,339,340-341,508 

Dawson (Sir William), on graphite of

original Laurentian............. 28

on lake Superior .................... 54

on lake Superior, sandstone..... _. 157,158

on relations of Huronian and Laurentian........................... 177

on relations of Algonkian and

Archean.......................... 192

onMurraybay ......_............ 219

on cape Breton and Nova Scotia... .239-240,

244,242 

on Nova Scotia granite .. _....... 245

on Nova Scotia slate __........... 245

on Nova Scotia schist..........._ 246

on pre-Cambrian succession ....... 458,459

on Laurentian. ___ _.. _. _ 489 

DeGeer, on Sweden.._.._....__ 526

Delaware, literature of._.__.... _ 412-413

pre-Cambrian of._......_.__. 415

De Ranee, on Grinnell land... _...... 216

Dewey, on Massachusetts........_.... 361-362

on Primitive......................_ 470

Dickenson, oh lake Superior........ _ 75

Diller, on Boston, Massachusetts... _ 369

Dodge, on Massachusetts.._.._._ 366

Ducatel, on Maryland.____..___ 410

on Primitive........._............ 470

Page.

E.

E"atnes, on northern and northeastern

Minnesota ..............._...._. 119

Eastern sandstone, Junction with Keweenaw series.Irving and Chamberlin on....................... 140-142

Eastern townships, literature of..__ 223-227 

Ells on............................... 226-227

Algonkian of..................226-227,501-502

Huronian of.......................... 226-227

Eaton (J.H.),ontheBarabooquartzite. 107 

Eaton (Amos), on New York .......... 387

on Primitive rocks.._.._.._ 440,470 

referred toby Hunt....__.._ 464

Eganrange, Algonkian of ..___ 506 

Elk mountains, literature of...._.... 317-318

Elliott on Tennessee .._...____._ 423 

Ells, indebtedness to.................... 16,17

on the Eastern townships....234-225,226,227

on the Quebec group ..._.._.... 225

on Gasp6 peninsula .................. 227

on New Brunswick...228,229,233,234-235,236 

on Caledonia mountains ............ 233

on Coldbrook group............._ 233

on southern New Brunswick....... 238

on granite of Eastern townships... 501 

Emerson, onFrobisher bay............. 2l6~-2l7

on Massachusetts ........369-370,370-371,415

onNewEngland ..............__ 382,385

on New England granites........... 384

Emmons (E.), on New York .387,388,389,393-349 

on North Carolina................419-420,428

on metamorphism................... 428

on dioritic schists from eruptives . .428,429,

481-482 

on pre-Cambrian succession. ....429,440-442

referred to by Hunt........_..._ 464,465

on Azoic. _.. ....... .... 477

on Primitive.___.._.__.... 470

onTaconlan......_.._.._..... 474

on origin of Archean........479,481-482,486

on delimitations of Arche an........ 486

Emmons (S. F.), on Rawlingspeak..... 274

 onUintamountains ................ 288-289

on Wasatch mountains ..290-291,293-294,298 

on Oquirrh mountains _ ___ _. 295 

on Aqui mountains......__._ 296

on Nevada ..... __.. __ _.. _. 300-303

onFront range ..........__..... 312

on Sangre deCristo mountains..... 314

on Sawatch mountains ........._ 316

on Quartzite mountains .___ 320

on origin of Archean _..._..._ 479

Emory, on California.................... 334

Eudlich,on Rawlings peak.... ____ 275

on Sweetwater mountains _.__ 278-279 

proposes Prozoic.-..._._.......... 278-279

on Wind River mountains.......... 279-280

on Wyoming......................... 281,282

on Front range............_...._ 310-311

on Wet and Sangre de Cristo

mountains _...__.......... 313,314

on Sawatch and Quartzite mountains...........................316,319-320

on Quartzite mountains ... _. __ 319-320 

onLaPlatamountains_______ 323-324
536 INDEX.

c Page. 

272 

278 

278 

245 

447 

458

Engelmann, onLaramie range.. ... 

on the Rattlesnake mountains.....

on Sweetwater mountains.. ... 

Eophyton in Nova Scotia slates.......

Eozoic, Dana on. ....................

Sir William Dawson on. _._..._....

use of term__.._..,.-._.... 473-474

Eparchean, proposal of, Xrvingon ..148,461,462,

475,493 

Era, use of term......................... 475

Eruptives, Animikie district........... 173

Huronian .._..................... 47

Keweenawan ...... ----- 173

lake Superior................169-170,173-174

lake Superior, relations to Archean ........................... 192-193

Marquette district.................. 173

Menominee district........ .. 173

Penokee district.........._..'..... 173

F.

Faribault, on gold-bearing rocks of

NovaScotia...................... 244

on Nova Scotia granites and schists. 245,246 

Felch mountain, Rominger on. _...... 104,105

district, Pumpelly and Van Hise on 156 

district, succession in .............. 190,195

series, equivalents of ........... 190

Fernandian series of Comstock .....269,474,504

Fielden, onGrinneUland...__..... 216

Finch, on Pennsylvania ... . .. 404 

Fitton, on Great Slave lake..._..._ 214-215 

Fletcher, on Cape Breton and Nova

Scotia.......................242-243

on Cape Breton Laurentian _..... 246-247

Fontaine. on Virginia ... ............ 416,417

Formation, use of term......_........ 475

Fortieth parallel survey, on Uinta Mts 297 

on WasatchMts__..._...._ 297

Fossil from lake Superior, Wadsworth

on.......... ......-. ..... 88

in Animikie series .............. . 194

in Nova Scotia slates ... ___ 245 

in quartzite of Minnesota, N. H.

Winchellon _____ 124

in Sioux quartzites ................. 194

Fossils, of Animikie, Selwyn on........ 67,492

sparse in Algonkian................. 496-497

in Algonkian of Newfoundland _. 251 

in Laurentian of New Brunswick,

Matthew on....... ......._ 236

in Torridon......................_. 525

of Algonkian ........................ 469

of Azoic, Whitney and Wadsworth

on _........................ 455

of Grand canyon, Walcott on. __ 492 

of Huronian ......................... 194

of lake Superior Algonkian ........ 499

of Newfoundland, Murray, Howley,

and Walcott on.. _..... __249-250,492

Foster, on lake Superior... ..........74,75,76

on lake Superior sandstone _77,82,158,160 

on Keweenaw point......._....... 77

on the copper lands of lake Superior _.. .................. 78-79

on iron region of lake Superior._ 79-82

Foster Continued.

on Azoic of lake Superior ..........

on Keweenawan.._. _...........

on lake Superior succession.._.. 

. on iron ores of lake Superior.......

on lake Superior eruptives._.....

on unconformity within Huronian.

on origin of Archean ._ _........

France, Barrels on.... _ _ _.......

Michel-Levy on..__ __.... 

Frazer, on Pennsylvania _ _406-407,

on Azoic. _ _.._..__.... 

Fremont island, Algonkian of..........

range, literature of.....____.... 

Frobisher bay, Emerson on _ _.... 

Front range, literature of.._ ...308-313,

Algonkian of.___......_....

Fulton, on the Menominee district.....

Furman, on King's mountain, North 

Carolina_____......

G.

Gale, on New York county .............

Gander lake, Murray and Howley on .. 

Gasp6 peninsula, literature of _.......

Gastaldi, referred to by Hunt..........

Geiger, on Virginia ......._...........

Geikie, indebtedness to_....._......

on Wasatch mountains ._._..293,

on origin of Archean .._...........

onDalradian _ _. _.._......

on Great Britain ____ _........

on Torridon _ .__..._..._.

George river limestone series, Fletcher

on...................._.........

Georgia, literature of _ _ _ __.

Gerlach, referred to by Hunt.__.....

Germany, Credner on......_.........

Lessen on................._........

Gesner, on southern New Brunswick .. 

Gibbs, on lake Superior.._ __......

on Washington..._____......

Gilbert, indebtedness to___.......

on southern Utah and southeastern 

Nevada......'_....__......

on Arizona _......... ..........

on Grand canyon _.._.._....

on New Mexico _............... _.

on Archean of Arizona and New 

Mexico ._......._....._....

on Tonto sandstone.. ..... .....

on California ....____....

Gilpin, on Cape Breton .................

Glenn, on Texas .....__.............

Gogebic district, Rominger on .........

Gogebic iron range, Brooks on _.....

Gold-bearing rocks of Nova Scotia......

Faribault, Selwyn.and Silliman on. 

Grand canyon, Gilbert, Powell and Walcott on...'........ 326-329,331,329-

Algonkianof... .................

Grand Manan, Bailey and Matthew on. 

Grand river, literature of.... ........

Grant, on northeastern Minnesota ....

Gray, on lake Superior_____.___.

82,167 

161

163,165 

170 

173 

179 

481 

525 

525

409-410 

470 

506 

295

216-217

314-315

325,506

118

422

388 

250 

227

463,464

418

17

297-298 

482 

525 

525 

525

242,243

425,426

463

526

525

230,237

75

337

17

296

3.27-828 

327-328

331

331

335,341

243

267

105

93

240,241

241,244

-330,466 

507

232,233

318-319

130-131

73
INDEX. 537

Page. 

Great Barrington, Massachusetts,

Dana on.......................... 365,367

Julien on............................. 369

Great Britain, pre-Cambrian of..... _ 525

Great Slave lake, Richardson and Pitton on country north of.__... 213-215 

G reat Smoky mountains, Currey on... 422 

Greely, onGrlnnell land._............ 217

Green mountains, Massachusetts, Pumpelly on.......................371,372,415

Greenland, Haughton on ..._.._... 215,216 

Gregory, on Marblehead, Massachusetts.............................. 364

Grenville series, Selwyn on .__.__ 32,451 

Algonkian of ........................ 497

Greylock mountains, Massachusetts,

Dale on........................374-376,415

Grinnell land, De Ranee, Fielden and

Greely on........................ 216,217

Gros Ventre range, literature of . __. 280 

Group, use of term........ ........... 475

Gunnisonriver, literature of........... 318-319

H.

Hague, on Laramie, Medicine Bow, and

" Park ranges........_........... 272-274

on granites and gneisses of southern Wyoming.................... 277

on Wasatch mountains .._........ 291

on Promontory ridge, Fremont island and Antelope island ranges 295 

on Raft River range ................ 296

on Nevada ........................... 300-303

on Eureka district....... ........ 305

on origin of Archean _. ........ 379

Hall (Charles E.),on New York ........ 396

on Pennsylvania.................408,409,415

Hall (0. W-). on granites of Minnesota. 149 

on northeastern Minnesota......_ 121

Hall (James), on northern Wisconsin.. 106,119 

on southern Minnesota_..._.._ 119 

onNewYork ...................._ 397

Hall (S. R.), on Vermont................ 360

Harrison, on Missouri ......:_._.... 262

Hartley, onPictou coal fields .......... 241

Hartt, on southern New Brunswick.... 230,231

Hastings county, Vennor on.... ...,28-29,30,498

Hastings series, Loganon .............. 21,28

Hastings series, Selwyn on............. 32,451

Algonkian of......................... 497-498

Hauer, von, referred to by Hunt....... 463

Haughton, on north Greenland......... 215-216

on the Arctic archipelago. _ __ 216 

on Greenland......__ _...__ 216

Hawes, on New Hampshire. _ _._ 354-355 

on diorite schists.................... 384

on New England granites .......... 384

on origin of Archean................ 481

Haworth, on Missouri......._......263-264,264

Hayden, on the Black Hills......_.... .257

on Dakota. _ _ _ _ ______ 134

on Laramie range.__.__.... 272

on granites and gneisses of Wyoming.............................. 277

on Big Horn mountains ______ 277,278 

on Sweetwater mountains....__ 278

Page. 

Hayden Continued.

on Wind River mountains. __ _ 279 

on Madison river.._..._...__ 282 

on Montana...................282,283,284,268

onUinta mountains.___...._.. 287,297

on Wasatch mountains............. 289,290

on Oquirrh mountains______.. 295 

on Front range._..___..._ 30g 

onSawatchmountains.............. 316,317

onElk mountains________.. 317 

Herrick, on lake Superior............... 65

on relations of Algonkian and Archean............................. 177,192

on origin of Archean................ 481

Hicks, referred to by Hunt.............. 463

Hill,onlake Superior................... 75

Hind, onLabrador....................... 216

on southern New Brunswick ....... 231,237

on Nova Scotia granites............ 240,241

on Nova Scotia slates......_..... 245

on Nova Scotia schists....____ 246

Hitchcock (Charles H.), on Maine...... 348,345

on New Hampshire..... ..........351-354,359

on Vermont.......................... 358,360

on Massachusetts____............ 364

on Aquidneck, Rhode Island........ 377

on New England........,.,......379,380,381

referred to by Hunt..__........... 463

on Azoic...... ...... .... 470

Hitchcock (Edward), on Maine......... 348

onmetamorphism..__.__._. 356-357 

on Vermont..__.........356-358,358-360,385

on Massachusetts.............361,362,363,382

on New England granites........... 383

on Azoic.. ... .............. 470

on Primitive.............. ........ 470

on origin of Archean__..._._ 479 

on relations of granites and schists. 324 

on delimitations of Archean.._.. 485 

on lithological correlation...... _ 512

Holmes (J. H.), acknowledgments to... 16 

Holmes (W. H.), on Montana........... 284

on Elk mountains_...___ 317

on La Plata mountains. _.._._ 323

Holyoke formation, Wadsworth on.... 102

Hoosac mountain, Massachusetts, Wolff

On ......_---___.:.........372-374,415

Horton on Orange county, N. Y........ 388

Houghton on upper peninsula of Michigan ............................... 88,89

on lake Superior sandstone ....... 157,158

Howell, on Wasatch mountains........ 290

on southern Utah and southeastern

Nevada........................... 296

Howley, on Newfoundland...........249,251,492

on Newfoundland fossils......... _ 250,492

on Gander lake _.................. 250

onAvalonpeninsula.... .... 250-251

Hubbar d, on lake Superior............. 75,78

Hudson bay, Bell on........ ............ 70

literature of ......................... 209-212

Lyonon.... _...........I...... 214

Rae, on westcoastof................ 215

Huronian of.......................... 500

Algonkian of......................... 500-501
538 INDEX.

Paga

Hunt, indebtedness to_._. - 17 

on Laurentian ................24,462,465,474

proposal of Animikieby... ... 59 

on Vermont._..._....... 361

on Massachusetts ................... 365-366

on New York ....................... 395

on Pennsylvania ....._......... 407

on pre-Cambrian succession ....442-443,445-

447,462-466,510,511 

onNorian ........................462,465,474

on Arvonian.......... .. 462-463,465,474

on Huronian .......-.. - -463,465,466,474

onMontalban ................463-464,465,474

onTaconian ...__..........464-465,466,474

on Animikie ...._.................. 465

on Keweenawan..___......_.. 466

Hunters island series, unconformity

within.................. ....... 181/182

Huntingtonon Maine.... ... ----- 349

on New Hampshire.................. 351,353

Huron mountains, Michigan, Rominger on...........-.... ....... 95

Huronian .....___...._..... 40

relations to Laurentian . . 34 

Barlow, Bell, Bigsby, Bonney, Dana, 

Channing, William Dawson, Hunt, 

Irving, King, Locke, Logan, Murray, Pumpelly, Sehvyn, Wadsworth, Whitney, N. H. and Alex. 

Winchell, on.... .32,35,36,37,38,39,40,41,42,

43, 44, 46,47,48,442,443,444,

446,447,448,451,453,457,458,

459,460,461,462,463,465,466,

467,468,470,471,472,473,474.

literature of original.. . .. 35-48

proposed by Logan.... .. 38

'full section of ....................... 39

relation to Laurentian, Bell and

Barlow on........................ 42

relations to Laurentian..._..._ 44-49 

not metamorphic .................... 46

structure of _.._...._......_ 46-48

unconformably above Laurentian. 46-47 

eruptions of.____..._........ 47

literature cited ...................... 48-50

unconformably below Copper-bearing series, Logan on............. 55

uncomformably below Aminikie,

McKellaron.._._............ 65

unconformably below lake Superior sandstone, Credner on... 90 

unconformable with lake Superior

sandstone, Fulton on..._...... 118

separability of, from an underlying

series, Irving on.. ............ 146-147

unconformably below Keweenawan,

Irving on.............___... 147

unconformably above Laurentian,

Irving on... .... ........... 147

unconformity between Lower and

Upper, VanHise on ..._____ 154-155 

original, unconformity within...... 184-186,

498-499 

original, lake Superior equivalents

Of ................................ 185-187

Pago. 

Huronian Continued.

fossils of ......'......__............ 194

organic materialin.._........_ 194

conformable with Laurentian, Bell

on .............................209,210,211

unconlormably below Potsdam,

Murrayon....................... 249

relations .to Laurentian, Whitney

and Wadsworth on.............. 455-457

useof.... _...__.................. 470-473

relations to Laurentian . .471,472,473,495,498 

relations to Algonkian ...... _ _ 493

original of Algonkian in ............ 498-499

of Eastern Townships............... 226-227

of France, Barroison..._.._.... 525

of Hudson bay ._._._...._... 500

of Hudson bay, Bell on._.......... 212-213

of lake of the Woods, junction with

Laurentian .................. _' 60

of lake of the Woods, G. M. Dawson

on .______..._..... 60

of lake Superior..................... 168-169

of lake Superior, junction with Laurentian, Bell on.................. 59

of lake Superior, conformable with 

Laurentian, Bell, Logan, and 

Selwyn on'........................55,58,62

of lake Superior, Bell, Macfarlane,

and Whittlesey on..... ....56,57,68-70,86

of lake Superior, unconformably below Cambrian.______._ 69 

of lake Superior, unconformity at

baseof............................ 174,178

of lake Superior, unconformity

within........................... 179-184

of lake Superior, denned..._.._ 193 

of lake Superior, Algonkian._ _ 499 

.of lake Superior region...___ 473 

of Marquette district, Brooks on... 91-93 

of Menominee district, Brooks on.. 115-116 

of Menominee district, Fulton on.. 118 

of Michigan, Credner on ......_... 90

of Michigan, uncomformably above

Laurentian ...................... 90

of Michigan, Brooks on.._ __.... 96-97

Wright on.'....................... 97

unconformable with Laurentian... ...................... _.]97,112,113

Kominger on.........._........ 103-105

of New Brunswick, Bailey and

Matthew on.................... 232

of New Brunswick, southern....... 237,238

of Newfoundland.................... 251

of Northern Canada................. 217-218

of Penokee district, uuconformable

with Laurentian..........__.. 111,113

of St. Lawrence..................... 220

of Wisconsin, Irving on___.__ 112 

ol Wisconsin, Chamberlin on... 117 

of Wisconsin, northern, Irving on. 107,112 

of Wyoming......................... 281-282

Hydroplastic rocks, E. Emmons on.440,441,442 

Hypozoic, H.D.Rogers on...... . 470

use of term _.. ___ . .. 474 

of Pennsylvania.._ ........... 404
INDEX. 539

Page.

Ingall, on lake Superior................. 67

Invilllers d', on Pennsylvania. _...... 409

Iowa, quartzite of, White on.... _.... 119

Iron district of lake Superior, Wadsworth on......................... 86-87

Iron mountain, Michigan, Van Hise on 156

Iron ores, Michigan, Whitney on .. 75

lake Superior........................ 170-173

of lake Superior, Foster and Whitney on..__..___...__..__ 79-82 

of lake Superior, Irving on...... 144-145

of Minnesota, N. H. and H. V. Winchell on .- ..........125,126,130,131,132

of Penokeff-Gogebic district, Van

Hise on........................... 148-149

of Animikie, Kaministiquia, Vermilion.Penokee.Marquette, and 

Menominee districts.......... 171,172,173

of Missouri, Schmidt on............ 263

Iron regions of Minnesota, H. V. Winchell on...................... -. 130

Iron-bearing series of lake Superior,

Brooks on.......'................. 91

Irving, indebtedness to._....... 16,19

onHuronian.__.._..._....... 40,47

on Portland quartzite ........... 107

on Sank Coiinty, Wisconsin ........ 107

on Wisconsin.107-108,109,110-111,111-113,116 

on the Penokee district............. Ill

on lithology of Wisconsin ._.__ 118 

on Copper-bearing series........._ 134-139

on quartz enlargements ........ _ 140

on junction of Eastern Sandstone

and Keweenaw series . _.. _ 140-142 

on divisibility of Archean .......... 142-143

on Archean of lake Superior. ..143-144,168 

on iron ores of lake Superior region ...........................144-145,171

on separability of Huronian from

an underlying series .... ..... 146-147

onpre-Cambrian... .. _...... 148

on the green stones of Marquette

and Menominee districts........ 149-150

on the Penokee series .............. 150-154

on lake Superior sandstone ........ 158,160

onKeweenawan...._.............. 161,162

on lake Superior succession .....164,165,166

on lake Superior Laureutian ...... 168

on lake Superior Huronian......... 169

on unconformity at base of Marquette series..................... 175

on unconformity at base of Menominee series........................ 175,177

on unconformity at base of Algonkian .............................. 176

on unconformity within Huronian, 179,180,

182 

on definition of Huronian . __.... 193

on lake Superior syncline....__ 196

on lithological correlation ......... 459,517

on correlation by unconformity.. 459-460,518 

on pre-Cambrian succession.459-462,475,509 

proposes Agnotozoic............. 461,462,475

proposes Eparchean.._._....461,462,475

Page. 

Irving Continued.

on Agnotozoic.____.__...... 491,493

on Proterozoic ___..____._.. 493 

on Eparchean............. 493

on Algonkian stratigraphy____ 511

J.

Jackson, on lake Superior sandstone.. 74-75,

75-76,84,85,1^158

onlake Superior .._...... 75

on Keweenaw point........... 75

onKeweenawan.._.._......._ 161

on Nova Scotia granites ............ 239,244

on Maine............................. 348

on New Hampshire............. 350,351

on Massachusetts.................... 364,365

onRhode Island..................... 377

on New England granites .....__ 384

on New Jersey limestones .......... 400

on Primitive......................... 470

on origin of Archean.__....._. 479

Jameson, on Baffin bay ........._._. 214

on Melville peninsula ....... _ _ 214

Jessup, on Essex county, N. Y._...... 387

Johnston, on southern New Brunswick ............................. 230

Jones, onlake Superior....._........ 65

Jukes, on Newfoundland............ 247-248,251

on cleavage................._.._ 252

on pre-Cambrian succession.... _ 474

on origin of Archeau............_ 479

Julien, on Great Barrington, Mass.... 369 

on Adirondacks __._ __. 396

K. 

Kaministiquia district, iron ores of.... 171,172

Kaministiquia series,imconformity

within.........'................... 181,182

unconformably below Animikie _ 182

relations to original Huronian_ 185

Kane on Peabody bay, Greenland . _ 215

Keating on Franklin, N. J ............. 399

Keewatin, Bell and Lawson on.63-65,66,169,468 

conformable with Coutchicing,

Lawson on..__................ 66

unconformably below Animikie,

Alex. Winchell on ............... 128

conformable with Vermilion, N. H.

Winchell on...................... 129

unconformably above Coutchicing 176 

relations to Algonkian and Archean 192,194 

proposal of, by Lawson............. 474

Keith, on Virginia....................... 41g

Kenip, on Manhattan island, New

York ............................. 397

Kent peninsula, Simpson on ........... 215

'Kerr, on North Carolina.........420-421,421-422

referred to by Hunt.._....___ 465

on Azoic ...........__.._..__ 470

Keweenaw peninsula, Locke on ..._ 73 

Keweenaw point, Foster, Jackson, and

Whitney on...................74,75,76,77

Keweenaw series, junction with Eastern Sandstone, Irving and Chamberlin on........................... 140-142

(See Copper-bearing rocks.)
540 INDEX.

Page.

Keweenawan, unconformable with AnImikle, McKellar on ............ 65

Bayfleld, Bayley, Bell, Brooks, Foster, Hunt, Irving, Jackson, 

Logan,Marvine, Mei'riam, Pumpelly,Selwyn,Wadsworth,Whitney, and N. H. Winchell, on...-.102,161, 

162,460,461, 462,4fi6

unconformable with Penokee, Irving on............................ 112-113

of northern Wisconsin, Irving on.. 112-113 

of Wisconsin, Chamberlin on....... 117-118

unconf ormably below lake Superior

sandstone, Irving on. _ _ _ 113,147 

unconformably below lake Superior, Wooster on ..____ 118 

unconformably above Huronian,

Irving on......................... 147

unconformably below lake Superior sandstone__._____ 156,157 

defined........... ................... 160-162

unconformably above Animikie._ 161-162 

eruptives ................. ........ 173

unconformity atbaseof... __.... 174,178

position of, Selwyn and N. H. Winchell on .......................... 194

of northern Canada. _ _ _ _ 218

use of term ._..._.._.____. 472,474 

of lake Superior, Algonkian........ 499

Keweenian, series, Selwyn on .......... 62-63

Keweenawian, proposal of, by Brooks. 96 

defined............................... 160

(See Copper-bearing series, and

Cupriferous series).

Keyes, on Maryland_.. _.. _. 411 

Kimball, on the Marquette district... 86 

King (F. H.), on northern Wisconsin.. 116 

King (.Clarence), on the Color ado, Medicine Bow, and Park ranges..... 274-275

on granites and gneisses of southern Wyoming.................... 277

on Wasatch mountains __........ 291-293

on Unita mountains.._.___.... 289

on Aqui mountains__............ 296

on Nevada.....___.._. ....... 303-305

on Archean granite . ...__. 306 

on Colorado range...... ............ 312

on relations of granites and schists. 324 

on pre-Cambrian succession._ _ 448-451 

on origin of Archean.......... 479

on Colorado Huronian...._.__ 506

King (H.), on Missouri.................. 261

Kingston group......................... 237,238

Bailey, Matthew, and Hartt on.230,231,232,

233,234

Kitchell, on New Jersey highlands.... 400

Kloos, on Minnesota..._._._._ 120

Konlug, onBafflnbay.. ............. 214

Labrador, Bell, Hind, Lieber, Packard

and Steinhauer, on...........213,216,217

Labradorian, Logan on..___........ 444

Hunt on_____^ _______ _ 446

Page. 

Labrador!tes of St. Lawrence.......... 220

LaFlamme, on the Saguenay region.. 219 

Lake Huron, Archean of _ _ _. _ 475 

Lake Mistassini, literature of..._.... 218-220

Lake of the Woods, Bell, Bigsby, G. M. 

Dawson, Lawson, and Selwyn 

on.................51,53,58,59-60,62,63-65

Lake St. John, literature of ............ 218-220

co untry north of, Richardson on... 219 

Lake Superior, literature cited ...._ 199,208

Algonkian........................... 499-500

Algonkian, unconformities within. 500 

Algonkian, unconformably above

Archean.._...______..... 500

Archean.............................. 475,487

Archean, relations to eruptl ves..... 192-193

Archean, origin of........._.__ 198

Archean and Algonkian, unconformity between...................... 174-178

eruptives......................169-170,173-174

formations, correlation of._.__ 198-199 

Huronian.........................168^169,473

Huronian, unconformity at base of. 174-178 

Huronian, unconformity within_ 179-184 

iron ores............................. 170-173

Laurentian .___....___ 473

nomenclature___.____...._ 191-194

region, literature of..___.._ 51-199 

region, succession in............ _ 162-167

sandstone, Agassiz, Bayfleld, Bell, 

Bigsby, Brooks, Burt, Chamberlln, William Dawson, Foster, 

Houghton, Irving, Jackson, 

Locke, Logan, Macfarlarie, Marcou, Norwood, Owen, Pumpelly, 

H. D. Rogers, W. B. Rogers, 

Rominger, Schoolcraft, Selwyn, 

Strong, Sweet, Wadsworth, 

Whitney, Whittlesey, Wight, 

N. H. Winchell, and Wooster on. 51, 

52,56, 57, 70, 73,74-76, 77, SI82, 83-85, 95, 1.02,103,108-110, 

113,137-138, 157,158, 159, 160 

sandstone, unconformably above

Copper-bearing series, Logan on 55-56 

sandstone, unconformably above 

Copper-bearing series, Macfarlaneon._._.1............_ 55-57

sandstone, unconformably above

Animikie, Hunt on.............. 59

sandstone, unconformably above 

Copper-bearing series, Brooks 

and Pumpelly on ............. 90

sandstone, unconformably above

Huronian, Credner on........... 90

sandstone, unconformably above

Keweenawan, Irving on ........ 113,147

sandstone, unconformable above

Huronian,Fulton on.._...... 118

sandstone, unconformably above

Keweenawan, Wooster on.. . 118 

sandstone___........._......_ 157-159

sandstone, unconformably above

Keweenawan _...._... .. 157-160

series, correlation of................ 183-195

succession........................195,196-197
INDEX. 541

Page. 

Lake Superior Continued.

succession,Logan on................ 197

syncline.._ ... ........ 196

unconformities,universality of.... 197-198

Lake Winnipeg, Bell on ................ 59,61

Lakes, on Front range... -. -- 318-313 

on Sawatch mountains .... 316 

on Elk mountains.......--.....-..-- 317,318

on Quartz! te mountains.-..----. 320

on Colorado Archean and Algonkian 325 

Laphatn, onthePenokee range _......- 106

La Plata mountains, literature of...... 323-324

Laramie range, literature of ............ .272-276

Laurentian, original, literature of-.... 23-35

F. D. Adams, Bell, Bigsby, Dana, 

William Dawson, Hunt, Irving, 

King, Lawson, Logan, Macfarlane, Murray, Selwyn, Vennor, 

Wadsworth, Whltney, Wilkins

on ....23,34,63-65,442,444-446,448,451,453,

457-460,462, 465-468,470-474 

proposal of, by Logan............... 24,25

Kr aphite of, William Dawson on.... 28,219

original............... ... ...... 32-35

anorthosite and eruptives of........ 33

unconformity in_.. ............. 34

relations to Huronian .....34,44-48,471,472,

473,495,498

relations to Huronian, Barlow on.. 42 

unconf ormably below Huronian.... 46

literature cited..____.._........ 48-50

unconf ormably below Copper-bearing series, Macf arlane on... _ 56 

conformable with Huronian, Bell

on......... _.... ........58,209,210,211

unconformably below Huronian,

Irving on ........................ 112,147

unconformably below Silurian,

Hindon.......................... 241

relation to Huronian, Whitney and

Wadsworth on.........__. __ 455-457

relations to Norian ......._.._ 471

unconf ormity in_.... ...._..... 471

included in Archean..............475,488-490

use of term ..................470-474,489-490

original, Algonkian in._......_ 497-498

of Cape Breton ....... .............. 246,247

of Hudson bay, Bell on.............. 212-213

of lake of the Woods, G. M. Dawson

on................................ 59-60

of lake of the Woods, junction with

Huronian, G. M. Dawson on.... 60

of lake Superior, conformable with 

Huronian, Logan, and Selwyn 

on................................ 55,62

of lake Superior, Macf arlane on ... 56,57 

of lake Superior, Whittlesey on_ 86 

of lake Superior, junction with Huronian, Bell on.._._____ 59 

of lake Superior, character of...... 167-168

" of lake Superior, denned. ___.__..191.192,473 

of Menoniinee district, Brooks on.. 115 

of Michigan, Credner and Wright on 90,97 

of Michigan, unconformably below

Huronian, Credner on.__._ 90

Page. 

Laurentian Continued.

of Michigan, unconformable with 

Huronian, Wright, and Brooks 

on ................................ 97

of New Brunswick, Bailey and

Matthew on._.................. 231-233

of New Brunswick, fossils in,

Matthew on.__.___.__ 236 

of Newfoundland___.......__ 251,252

of Nipissing.._____....._.__ 34

of northern Canada......____ 217-218

of Nova Scotia..._................. 246

of Penokee district, unconformable 

with Huronian, Chamberlin and 

Wright on....................... 111,113

of Rainy lake, Lawson on. ___ _ 66-67 

of St. Lawrence .________ 220

of southern New Brunswick........ 237,238

of Wisconsin, Irving on ..........107,111-112

of Wisconsin, Chamberlin on ._.. 116-117 

Law of uniformity ...................... 513-514

Lawson, on the lake of the Woods..._ 63-65 

of Wyoming............. ......... 281-282

on Rainy lake region................. 65-67

on Archean of central Canada__ 68 

proposal of Ontarian system__. 68,474 

on lake Superior stratigraphy ..... 70

on lake Superior sandstone..... .165,166,167

on Laurentian of Lake Superior... 167.168 

on Coutchiching..................... 169,490

onKeewatin.. .. ..... 169

on Lake Superior Huronian........ 169

on relations of Keewatin and

Coutchiching .................... 176,178

on unconformity within Huronian.... -- --..- .. 179,182-183

on relations of Algonkian and

Archean. ............. 192

on Ontarian............ .... . 193-194

on relations of granites and schists. 324,325,

383 

proposes Keewatin. ....__.. 474

proposes Coutchiching.............. 474

on origin of Archean.............479,480-481

stratigraphy of Archean.. _...... 488-489

Leeds, on Adirondacks........._.._ 395

on Philadelphia, Pa................. 406

Lehmann, indebtedness to.............. 17

on origin of Archean............_. 482

Lesley, on Pennsylvania... ......_. 408-409

Leslie, on Melville peninsula........... 214

Lieber on Labrador . ........... 216

 on South Carolina................424,425,428

on metamorphism. ............... 428

on dioritic schists from eruptives.. 428,429,

481-482 

referred toby Hunt......._____ 464,465

on pre-Cambrian succession .. ___ 474 

on origin of Archean..._.......479,481-482

Life of Archeozoic, Dana on ..._._ 469-470 

Limestones of New Jersey.... ..... 414

Literature, general, cited. ____ 527-529 

of Cordilleras cited..____........ 342-347

of eastern Canada cited_._ _. 252-255 

of Huronian cited...........____ 48-50
542 INDEX.

Page. 

Literature Continued.

of Lake Superior cited..:........... 199-308

of Laurentian cited .___.......... 48-50

of middle Atlantic states cited...... 433-437

of Mississippi valley cited.. _. _. 270-271 

of New England states cited........ 429-138

of Newfoundland cited........._. 255-256

of northern Canadacited............ 220-222

of southern Atlantic states cited._ 437-439. 

Lithicera, Dana on.......... ........ 469

Little on Georgia...... ................. 426

Llano series of Walcott _. ...__ 269 

Locke, onHuronian....... ._.__. 35-36

on Keweenaw peninsula...._._ 73

on lake Superior sandstone._.... 73

on lake Superior .. _._ _. __ 75,76

Loew, on Front range.._. .._..._ 314

on California ........._............ 335-336

Logan, on Laurentian .23,24,25-27,28,33,34,470- 

471,472-473,489,491,498

proposal of term Laurentian. _24,25,219 

on Hastings series........ ...__ 27,28

on Huronian.35,36-37,38,39-40, 46-48,470-471,

472-473,491,499

proposal of Huronian............... 38

on lake Superior,__..._..._52-53,54-56 

on succession on north shore of lake

Superior .._._ _.____. 53 

on lake Superior sandstone......... 157,158

on Keweenawan_................. 161,162

on lake Superior succession.... _ 163,197

on lake Superior eruptives ......... 173

on relations of Huronian and Laurentian............ ........... 177

on relations of Algonkian and Archean......_._._.._.._ 192

on lake Superior syncline _. __ 196 

on the St. Lawrence river ...... _ 218

on district north of St. Lawrence

river_..._.__.___._ 219 

on the Quebec group................ 223

on Pictou coal fields.....___.. 241

on pre-Cambrian succession.442^43,444-445

referred to by Hunt................. 465

Long, onFrontrange__ ......_ 308

Lessen, indebtedness to.. _._ 17

on Germany___. __.... 525

Low, on lake Misstassini.. .......... 220

on Gaspe" peninsula_ ....._ 227

Luther, indebtedness to...... ........ 17

Lyell, on Worcester, Massachusetts. _ 363

Lyon, on Hudson bay.._... .... _ 214

M.

McConnell, on the Pelly-Yukon......... 217

on Slave river....................... 217

on British Columbia ................ 339

McCormick, on Craftsbury, Vermont.. 361

McCulloch, onBafflnbay............... 213

Macf arlane, on Laurentian.... __ _ 27,489

on lake Superior ...__.__.._56-57,58

on Canadian stratigraphy.. _ _ 61-62

on lake Superior sandstone......... 158

on lake Superior succession . _ _ 163

on Laurentian of lake Superior _ 168

Page.

Macfarlane Continued.

on relations of Algonkian and Archean............................. 177,192

onRossie, New York-...._...._. 394

Mclnnes, on central New Brunswick... 229

Mclntyre, on lake Superior___... 75

McKellar, on the Animikie__ _ _. 65 

on Keweenawan...____.... 162 

on unconformity at base of Animikie................................ 182

Maclure, on Primitive and Transition

rocks..__......._......._ 440

Macoun, on British Columbia........... 337

Maine, Bailey and Matthew on _..... 231 

literature of ......................... 348-350

Manitounuck............................ 213

Bell on ............................... 209-210

group...___... __...... 500

Mapping, method of...."...... ........... 523-524

detailed results reached._........ 524

Marblehead,Massachusetts, Gregory on 164

Marcou, on lake Superior sandstone... 84,157 

on California.._....._......__ 335

Mareniscanof lake Superior, defined.. 191,192 

proposal of........................... 490

Marquette district, Kimball on. ... 86 

Huronian of, Brooks on.._....... 91-93

Rominger on...................97-100,103-104

Alex. Winchellon ................... 101

Wadsworth on.._..__...._ 102

greenstones of, Williams and Irving on..........,.............---- 149-150

Merriam on. _.....___. 156

eruptives of ____...__..._-- 173 

iron ores of .......................171,172,173

succession in............'..........189-190,195

Marquette series, unconformity at base

Of................................. 175

unconformity within................ 180,162

relations to original Huronian ._. 185-186 

equivalentsof.... ...i................ 189-190

Marquettian, proposal of, by Alex.Winchell............,-......... .... 128

defined............................... 193

Marsh on Uinta mountains _ _. _ 286 

Martin, on middle Atlantic states ...... 413

Marvine, on Copper-bearing series..... 94-95

on Keweenawan ..., .... ... 161

on Virgin mountains... ... 296 

onFrontrange..... .............. 308-310

on Park range.._..._.._.... 316

on Colorado Archean and Algonkian 324,

325,326 

on Arizona..........___.__...... 328-329

on relations of granites and schists. 383 

on origin of Archean...._ __ 479

Maryland, literature of ...._......... 410-411

pre-Cambrian of._...___ 415 

Mascarene series, Bailey and Matthew

on ................................ 232,233

Massachusetts, literature of _ _ _ 361 -376

Mather, on Connecticut and New York. 378

on New York..:_.......387,388,390-393,415

on New Jersey limestones ___... 414 

on Primitive......................... 470

on origin of Archean.._..__ 481
INDEX. 543

Page,

Matthew, on southern New Brunswick.230,231, 

233,234,235-238

on New Brunswick and Maine... 231 

on the Coldbrook group ............ 233

on Mascarene and Kingston series. 233 

on Kingston series.................. 234

on Laurentian fossils of New Brunswick..... .........--- -. 236

Meads, on the Stillwater, Minnesota,

deep well.__..... 131

Medicine Bow range......... .. ..276,277

literature of.......................... 272-276

Algonkiau of . - - - 504 

Melville peninsula, Jameson, Leslie, 

Hugh Murray, Parry, and Ross 

on................................. 214

Menomiuee district, Brooks, Fulton, 

Van Hise, Pumpelly, Rominger, 

and Wright on... .100-101,115-116,118,156

greenstones of, Williams and IrvIng on........ -- --.-.--. 149

succession in ...... ..... .. 190,195

eruptives........... ... 173

iron ores of........ . 172

series, unconformity at base of .... 175

imconformity within ............180,181,182

equivalents of ------------ . 190

Merrlam, indebtedness to............... 17

on the Marquette district _... __ 156 

on Keweenawan _______ . 162

on lake Superior eruptives ......... 173

Merrill, on New York................... 397

Mesabi range, A. H. Chester on ........ 123

N.H.Winchell on.................... 123-124

Metamorphic, use of term . . _ 474,480 

Metamorphic granite. King on. ..... 449-451

Selwynon ............. .... 451-452

Metamorphic schists from eruptives...428,429,

481-482

Metamorphism, Edward Hitchcock on.356-357,

382-383 

in New England ..........'.......... 382-383

Michel-Levy, indebtedness to.....__. 17

on France......... ..... 525

Michigan, literature of.................. 88-105

Middle Atlantic states, literature of... 386-413 

literature of, cited................... 433-437

Minnehaha county, Dakota, quartzites

of, Uphamon...... ....._... 124

Minnesota, literature of................. 119-133

north ern, succession in...... _. 190-191,195

series, equivalents of................ 190-191

valley, N. H. Winchell and Upham

on ........--.------.---.-......... 120,121

Mississippi valley, literature of........ 257-269

literature cited...................... 270-271

Missouri, literature of .................. 261-265

Algonkian of................. ..... 256,504

Mitchell, on North Carolina.____... 418,419 

on Primitive......................... 470

Montalban, Whitney and Wadsworth

on .............. .............. 457

Hunt on ......................463-464, 465,474

Montana, literature of......._........282-286

Archeanof.. ...................... 286,475

Algonkian of._...._..........286,504-505

Moose river and adjacent country, Bell

on ..........'...................... 61,211

Mount Desert, Maine, Shaler on ....... 349-350

Murchison on cape Granite ............ 215

Murray (Alexander), on Laurentian... 23,24,

33,34,472-473,498

on Huronian............35,36,37,38,39,46-48,

470-471,472-473,499

on lake Superior.._._._..._ 63 

on lake Superior eruptives......... 173

on the Notre Dame mountains __ 223 

on Notre Dame bay ................. 248-249

on Newfoundland...__.__.__ 248,251 

on Newfoundland fossils ........249,250,492

on Newfoundland Huronian.... _ 503

on Bonavista bay. . ........ 249

on Gander lake .. .. _ 250 

on St. George bay._____..__ 250 

on Avalonpeninsula................ 249-250

Murray (Hugh), on Melville peninsula. 214 

Murray bay, William Dawson on _.. 219 

Murrish, on central Wisconsin......... 107

N.

Nash, on Hampshire county .Massachusetts............................__.. 362

Nason, on New Jersey........ . . 403-404

on New Jersey limestones.......... 414

, on New Jersey gneisses ..._ 415

Nevada, southeastern, literature of _. 286-296

northern, literature of .............. 299-305

Archeanof........ ................ 306,307

Algonkian of ........................ 307-308

Newberry,on Front range..... .. . 314-315

on California .................333,334-335,336

onNew York ..... ................ 395

New Brunswick, literature of ...227-229,230-236 

southern, Huronian of.............. 237,238

southern, Laurentian of............ 237,238

southern, pie-Cambrian succession

in.......-......- . . . 238

southern, Algonkian of..._., . 502 

New England, pre-Cambriau of ........ 382-386

New England states, literature of...... 348-381

literature of, cited................... 429-433

Newfoundland, literature of............ 247-251

literature of, cited................... 255-256

Huronian of.-_. - ......._.... 251

Laurentian of........................ 251-252

Archean of.......... ............. 475-476

Algonkian of ..... .. .......... 503

New Hampshire, literature of.......... 350-355

New Jersey, literature of............... 399-404

limestones of ........ ....... 414

pre-Cambrian of.. .... ....... 414

New Mexico, literature of.... ....308-324,326-332

northern, Archeanof ... _.... 324-325

northern, Algonkian of . _.... __ 325

Newton, on Black Hills..........257-259,260-261

New York, literature of ..,_... 386-396 

pre-Cambrian of........___.. 415

Nipigon, proposal of, by Bell..... 61

unconlormably above Animikie,

Bell on............................ 70,468

unconformably below Potsdam,

Bell on ........................... 468

formation, Bell on .... .. 70,468
544 INDEX.

Page. 

Nipissing, Laurentian of __ _....... 34

Algonkian of.--...-._«.__..._ 497 

Norian, of Adirondacks._............ 413

Adams, Hunt, Selwyn, Wadsworth,

and Whitney, on........ 451,453-454,457-

458,462,465,474 

relations to Laurentian.... _....... 471

Norian series, Selwyn on............... 32

North Carolina, literature of ........... 418-422

North Somerset, Haughton on ..... 216

Norway, Reuschon ....._...._._ 526

Norwood, on Minnesota and lake Superior............................... 74,83

on lake Superior sandstone .... _ 157

on Missouri.......................... 263

Notre Dame mountains, Murray on_>. 223 

bay, Murray on...................... 248-249

Nova Scotia, literature of .............. 239-244

Algonkian of........ .............. 502-503

granite............................... 245

schist................................. 246

slates..............................245-246,247

O.

Oceanic era, Dana on.................. 469

Ogishki conglomerate, Alex. Winchell

on ................................ 127-128

OlenellusofNewfoundland.Walcotton. 251 

Olmsted, on North Carolina _........ 418

Ontarian, proposal of, by Lawson ..... 68,474

defined............................... 193-194

Ontario, eastern, literature of.......... 23-32

western, succession in _..._190-191,195 

Ontario series, equivalents of.......... 190-191

Oquirrh mountains, literature of __. 295 

Organic material in Huronian.......... 194

OriginalHuronian,lake Superior equivalents of......................... 185-187

Ottawa river, Algonkian of............. 497

Owen, on lake Superior.......__._73-74,82

on lake Superior sandstone... .73,83,157,158

on lake Superior syncline _.. _ 196 

on Unaka mountains, Tennessee... 422

P.

Packard on northern Labrador _.. 217

Paleontology in Algonkian stratigraphy ..............._.......... 514

Park range, literature of............. 272-276,316

Parry, on Melville peninsula ........... 214

Peabody bay, Greenland, Kane on...... 215

Peale, on Wind river mountains ___ 280,289 

on Uinta mountains................ 289

on Montana.._...__...282,283-284,286,299 

on Three Forks sheet, Montana.... 284-286

on Wasatch mountains ..........290,316,317

on Sawatchmountains..__ _ 316 

on Elk mountains __.... _. _. 317

onFrontrange_____......._ 310

on Gunnison and Grand rivers _. 318-319 

Peck, on Georgia.._ _.. __ __. 425 

Pelly-Yukon, McConnell on _ _.... 217

Pennsylvania, literature of...____ 404-410 

pre-Cambrian of _____.. _ _ 415

Page. 

Penokee, unconformably below Keweenawan, Irving on................ 112-113

equivalent to Animikie series .. _. 187-189 

Penokee district, Chamberlin, Irving,

and Wrighton._..__......... 111,113

iron ores of _______........_ 171,172

eruptives of _. __............... 173

succession in......................187-189,195

Penokee-Gogebic district, Alex. Winchell on .......................... 101-102

iron ores of, Van Hise on..__.... 148-149

Penokee range, Whittlesey andLapham

on................................. 106

Penokee series, Irving and Van Hise on 150-1154 

unconformity at base of _..... 175 

unconformity within___.. '._ 181,182 

relations to original Huronian ..... 185

equivalents of.._.....-.-..-. . 187-189

Percival, on the Baraboo and Portland

quartzites.._____... .._ 105 

on Connecticut....._..........378-379,385

on cleavage and stratification. _. S84 

on New England granites..... . 384

on Primitive. ....... ........... 470

on pre-Cambrian succession . _ _ 474 

Period, use of term.... ............ 479

Perry, on Worcester, Massachusetts... 365 

Pictou coal fields, Logan and Hartley on !J41 

Pierce, on New Jersey Highlands....... 399

on Staten island, New York ........ :586

Pifion range, Algonkian of.__ _ 506 

Pipestone quarries, Catlin on.. __ , 72 

Pogoniprange, Algonkian of.. _ !506 

Portland group.......__............... !238

. Bailey, Matthew, and Hartton..... 230,231

Portland quartzite, Percival and Irving

on . _..... ........ ... ..-. 105-107

Potsdam, unconformably above Huronian, Murray on '........... ... 249

Powell.on Uinta mountains._...__ 287,288

on Grand canyon of the Colorado.. 326-327,

, 329,331

on Archean of Arizona and New

Mexico ._.._...._.,....._.... 331

on Tonto sandstone ................. 331

Pre-Cambrian of Delaware . _.... _ 415

of Europe........____._....... 524-527

of Great Britain..................... 525

of Maryland...___................ 415

of New England.__............... 382-386

of New Jersey.._.._.............. 414

of New York......................... 415

of Pennsylvania..................... 415

succession of southern New Brunswick.._____..__.... 238

Prime, on Lehigh County, Pa.......... 407

Primitive, Akerly, Alexander, Booth, 

Dewey, Ducatel, AmosEaton, E. 

Emmons, Edward Hitchcock, 

Jackson, Mather, Mitchell, Percival, H. D. Rogers, W. B. 

Rogers, Silliman, Tuomey, and 

Vanuxemon...._______ 470

use of term._.._________. 470-473 

rocks, Eaton and Maclure on.__. 440 

Primordial quartzite, N. H. Winchell

ona .............................. 128-129
INDEX. 545

Pago. 

Promontory ridge, Algoukian of....... 506

range, literature of............. 295

Proterozoic, Irving on .................. 493

Prozoic, proposal of by Endlich.....'... 278,279

use of term........ ................ 474

of Wyoming, Endlich on ............ 281-282

Pumpelly, indebtedness to.............. 16,17

on relations of Huronian and Laurentian.....__........... 44-46

on Huronian.............. ........ 47

on Copper-bearing series.....90-91,93-94,97

on Menomlnee and Felch mountain

districts................... ...- 156

on lake Superior sandstone 158,160 

onKeweenawan .._ ....._.._ 161,162

on lake Superior succession........ 164,166

on lake Superior Huronian ..... 168

on unconformity at base of Algonkian.........-- ..-- -- -176-177,178

on unconformity within Menominee

series............................. 180

oil unconformity within original

Huronian .................... .. 185

on Missouri..................262-263, 261-265

on New England..................382,384,385

on cleavage and stratification......385-386,

516-517 

on Adirondacks...................... 398

on Green mountains, Massachusetts. ..........................371,372,415

on disintegration...._.___...... 483

on Appalachian Archean ......._ 487

on Algonkian of Appalachians . _. 508 

on Algonkian stratigraphy....._ 511

Pyrocrystalline, use of term.... _ _ 474

rocks, E. Emmons on .........._.. 440-441

Pyroplastic rocks, E. Emmons on.._ 440

Q.

Quartzite mountains, literature of .... 319-323

Algonkian of......................325,326,506

Quebec, western, literature of...__ 23-32 

Quebec group, Logan on........_.... 223

Ells and Selwyn on ..............223,224,225

R.

Rae, on west coast of Hudson bay._.. 215 

Raft river range, literature of _._. 296 

Rainy lake, Bigsby on .................. 54

Lawson on.........._.........__. 65-67

Rainy lake rocks, Logan on......_._ 34,54

Rand on Pennsylvania.._.._...._ 410

Rattlesnake mountains, literature of.. 278 

Rawlings peak, S. F. Emmons on....... 274

Endlich on........................... 275

Red river, Bell on ....................... 59

Republic formation, Wadsworth on. _ 102 

Reusch, indebtedness to._.._...... 17

on Norway ... .._............... 526

Rhode Island, literature of ... _... _. 377 

Richardson (James), on country near

lake St. John.................... 219

on country near Great Slave lake.. 213-214,

215

Bull. 86 35

Page. 

Richardson (James) Continued.

onCoppermine river............. 214

on lower St. Lawrence........_... 219

on British Columbia ................ 337

Robb, on Cape Breton........._....... 242,246

on central New Brunswick .......227-228,228

Roemer, on Texas._..............._ 266

Rogers (Henry D.), on White mountains.............................. 350

on lake Superior sandstone..._. 73 

on New Jersey .......................399-400

on Pennsylvania .................404-406,415

on Azoic, Hypozoic, and Primitive. 470 

on origin of Archean......____ 479

Rogers (W. B.) on lake Superior....... 74

on lake Superior sandstone.......85,157,158

on White mountains......._.... 350

on Massachusetts.._.............. 363

on Virginia...................416,417,418,428

onPrimitive......................... 470

on lake Superior basin.............. 196

on lithological correlation ......... 512

Rominger on the Huron mountains,

Michigan...................._.. 95

on lake Superior sandstone ..95,157,158.160 

on Marquette district......._......97-100

on Menominee district._ _.. _ 100-101 

on Huronian of Michigan.....__. 103-105

on lake Superior succession........ 164,165

on Laurentian of lake Superior.... 168

on lake Superior Huronian.... _. 168,169

on Marquette district iron ores .... 173

on lake Superior eruptives......... 173

on unconformity at base of Marquette

series.._....................... 175

on unconformity at base of Menominee series........................ 175

on unconformity at base of Algonkian .............................. 176

on unconformity within Huronian. 179 

referred toby Hunt................. 466

on origin of Archean................ 481

Ross, on Melville peninsula ....._.... 214

Roth, on origin of Archean.............. 482

Ruffm, on South Carolina............... 423

Ruffner, on Georgia.._........._._ 426

S.

Safford,on Tennessee................422-423,428

on Azoic .-.----.-. ........... 470

Saganaga conglomerate, Alex. Winchellon................ .......... 127

Saganaga syenite, H. V. Winchell on.. 133 

Saguenay region, La Flamme on....... 219

St. George's bay, Murray on............ 250

conformable with Coldbrook group,

Bayley, Hartt, and Matthewon.230-231,

231, 232

St. John (Orestes), on Gros Ventre range 280 

on Wind River mountains. _...... 280

on Wyoming range.................. 280

on Wyoming.._._....... .... 281

on Tetonrange .._._... .... 281

on Front range .._... ...... 314

St. Lawrence Huronian......_.__ 220

St. Lawrence labradorites. __._ 220
546 INDEX.

Page. 

St. Lawrence Lauremian .. _......... 220

St. Lawrence river, lower, literature of. 218-220 

Algonkian of..............._...... 497

St. Louis slates, relations to Huronian. 186-187 

Sanders, on lake Superior ........ _... 73

Sangre de Cristo mountains, literature

of..........._................... 313-314

Saskatchewan, Bell on _.._.......... 59

Saiik county, Wisconsin, Irving on ._ 107 

Sawatch mountains, literature of.. _ 316 

Schell creek, Al gonkian of.............. 506

Schiel, on Humboldt mountains........ 299

on Sangre de Cristo mountains..... 313

on Grand river..................._ 318

Schmidt, iron ores of Missouri......... 263

Schmitz, on Alabama........_........ 420-427

Schoolcraft, on lake Superior ..........72,81-85

on lake Superior sandstone......... 157,158

Selwyn, on lake of the Woods.......... 58-59

on Laurentian. ..........._ 32

on Huronian.._.._.........._ 40

onlake Superior....__.....__ 62,63

on the Animikie ..................... 63

on fossils in Animikie series .....67,19.S492

on lake Superior sandstone._. _ 158 

onKeweenawan.._......._._ 162

on lake Superior succession ........ 163

on relations of Huronian and Laurentian... ...................32,40,174,177

on relations of Algonkian and Archean............................. 192

on position of Animikie series.. __ 194 

on position of Keweenawan ........ 194

on the Quebec group ................ 223,224

on the Eastern Townships 225,226-227,501-502 

on gold-bearing rocks of Nova Scotia................................ 241

on Nova Scotia slates ....._..._ 215

on British Columbia ................ 337

on pre-Cambrian succession.451-454,509,510 

on lithological correlation.......... 452-453

on unconformity in Laiirentian.... 471

on origin of Archean.._.......... 479

on lake Nipissing.................... 489

Series, use of term ...................... 475

Shaler, on Mount Desert, Maine._.... 349-350

on Boston..___....._........ 364

on Cape Ann ....._....____ 374

on New England granites........_ 380

Shumard (B.F.), on Sauk county, Wisconsin............._........_ 84

on Missouri.......................... 263

on Texas ............................ 269

Shumard (Geo. G.), on Texas........... 267

Silliman, on gold-bearing rocks of Nova

Scotia............................ 241

on Nova Scotia slates ............... 245

on Wasatch mountains ............. 289

on Connecticut.._.._..._ _. 377-378 

on Primitive.......... .............. 470

Silurian, unconformably above Laurentian, Hind on............._ 241

Simpson, on Kent peninsula _........ 215

Sioux quartzites, relations to Huronian .............................. 186-187

fossil in.............................. 194

Slave river, McConnell on ._......_ 217

Smith,on Alabama ......._....... _. 426

Smock, on New York ................... 396-397

Smyth, on Steep Rock lake, Ontario.. 70-72 

on lake Superior succession..._. 1&5 

on unconformity at base of Marquette series _ _ _ _. _. 175

on unconformity at base of Algonkian .............................. 176-177

on relation of Algonkian and Archean........_ ..'.......... ..... 192

on cleavage and stratification...... 5)5

South Carolina, literature of........... 423-425

Southampton island, Back on......o.... 215

Southern Atlantic states, literature of .416-427 

literature cited .......................437-439

Stansbury, on Laramie range.......... 272

on Promontory ridge, Fremont island and Antelope island ranges 2£5 

Steep Rock lake, Ontario, Smyth on ... 70- 7'2 

Steinhauer,on Labrador _...__ 213 

Stevens, on New York island _..._ 3&4 

Stevenson, on Front range .. _ ....311-312,315

on Grand and Gunnison rivers...... 318

on New Mexico Archean and Algonkian.............................. 324,325

on relations ol granites and schists 383 

on origin of Archean............__ 47i>

Stillwater, Minnesota, deep well, Meads

on ................................ 181

Stratification,relations to cleavage.384,385,386,

515-517 

Stratigraphy of Algonkian, principles

applicable to...._._........ 511-524

Streng,on Minnesota ..._._......... 120

Strong, on northern Wisconsin .....114-115,116

on lake Superior sandstone ._ _ 158

on lake Superior eruptives. _ _ 173

Succession in lake Superior region .... 162-167,

IT '36-197 

Sutherland, on Baffin land.............. 215

Swallow, on Missouri......._._..... 252

Sweden, De Geeron......._._.._ 526

Sweet, on northern Wisconsin ......108-109,116

on western lake Superior district.. 113-114 

on lake Superior sandstone ...._ 158

on lake Superior succession........ 164

on lake Superior syncline ...... _ 196

Sweetwater mountains, literature of.. 278-279 

Syncline of lake Superior............... 196

System, use of term.........___ 475

T.

Taconian, Hunt, Wadsworth, and Whitney on............ 457,464-465,465,466,474

proposed by E.Emmons .... _._ 474

Tennessee, literature of..._.......... 422-423

Tetonrange, literature of.._......... 281

Thompson, on Vermont...._....._ 356,360

Tight, onlake Superior................. 65

Texas, literature of ___............... 266-269

Archean of........................... 269,475

Algonkian of......................... 269,504

Texian series of Comstock._..._269,474,504
INDEX. 547

Page. 

Tonto, unconformably above Algonkian .............................. 331

Tonto sandstone, Gilbert on............ 331

Powell on............................ 331

Torridon,Geikie on ..._._........... 525

fossilsin ................ .......... 525

Transition formation of Bigsby ....._ 46

rocks, McClure on........_....... 440

Troost, on Tennessee.................... 422

Tuoniey, on South Carolina............ 423-424

on Alabama.......................... 426

on Primitive..---.................... 470

Tyson, on California.................... 332-333

on Maryland...----..--...-----.-.-.- 410-411

on origin of Archean................ 479

IT. 

TJimaMts., Algonkianof........... 297,505

fortieth Parallel Surveyon......... 297

literature of ........................ 286-289

Uuconformable series made conformable.......... ..............482-483,494-495

Unconformity, shown by discordance

of bedding........................ 519

shown by dynamic movements..... 519-520

shown by bedding and cleavage.... 520

shown by eruptive rocks............ 520-521

shown by crystallization......... 521

shown by basal conglomerates..... 521-522

shown by Held relations............. 522-523

at base of Animikie series ._...... 176,179

at base of Keweenawan............. 174,178

at base of lake Superior Huronian. 174-178 

at base of lake Superior sandstone. 157 

at base of Marque tte series......... 175

at base of Menominee series........ 175

at base of Penokeeseries..-...-....- 175

at top of Newfoundland Algonkian. 251 

between Animikie and lake Superior sandstone. Hunt on......... 59

between Animikie and Keewatin,

Alex. Winchell on............... 128

between Animikie and Keweenawan, McKellar on................. 65

between Archean and Algoukian.. - 331,495 

between Archean and Cambrian of

Massachusetts................... 371

between Coldbrook and Coastal

groups, Bailey on.._.......... 235

between Copper-bearing series and

Huronian, Logan on ............ 55

between Copper-bearing series and 

lake Superior sandstone, Brooks 

and Pumpelly on ...._........ 90

between Copper-bearing series and

Laurentian, Macf arlane on..... 56

between Grand canyon Algonkian

and Archean..._..___.. 507 

between Grenville and Anorthosite

series----...----------.----.-...-- 27

between Huronian and Laurentian. 46-47 

between Huroiiian and Potsdam,

Murray on..._...._._._ 249

between Huronian and Laurentian

of Penokee district, Wright on. 113

Pago. 

Unconformity Continued.

between Huronian and Laurentian 

of Penokee district, Chamberlin 

on................................ Ill

between Huronian and Laureutian

of Wisconsin, Irving on ........ 112

between Keewatin and Coutchiching, Lawson on ............... 176

between Keweenawan and Animikie................................ 161-162

between Keweenawan and lake Superior sandstone, Irving on .... 147

between Keweenawan and Penokee, Irving on................... 112-113

between lake Superior Archean and

Algonkian ........................17-1-178

between lake Superior Huronian

and Cambrian, Bell on.......... 69

between lake Superior sandstone 

and Copper-bearing series, Logan on.......... ............... 55-56

between lake Superior sandstone 

and Copper-bearing series. Macfarlane on........................ 56-57

between lake Superior sandstone

and Huronian, Credner on..... 90

between lake Superior sandstone

and Huronian, Ful ton on....... 118

between lake Superior sandstone

and Keweenawan, Irving on ... 113 

between lake Superior sandstone

and Keweenawan, Wooster on. 118 

between lake Superior sandstone

and Keweenawan................ 157-160

between Laurentian and Huronian 

of Michigan Credner, Irving, 

and Wright on..........._.....90,97,147

between Montana Algonkian and

Archean.._.._.........._ 505

between Lower and Upper Huronian, Van Hise on.............. 154-155

between Nipigon and Animikie, Bell

on................................. 70,468

between Nipigon and Potsdam, Bell

on ................................ 468

between Silurian and Archean, Dana

on ................................ 447

between Silurian and Laurentian,

Hind on........_._........... 241

between Tonto and Algonkian ..... 331

in correlation ....................... 518-524

in correlation, Irving on._...._ 459-400

inLaurentiau ._.....................34,471

within Hunters island series ..._ 181,182 

within Kaministiquia series ....... 181,182

within lake Superior Huronian .... 179-184

within Marquette series............. 180,182

within Menominee series .......,180,181,182

within original Huronian .. _ _. -198 -199 

within Penokee series............--- 181,182

Unconformities of lake Superior, universality of...................... 197-198

within lake Superior Algonkian.... 500

within Grand canyon Algonkian... 507 

within original Huronian.. _.. _ 184-186
548 INDEX.

Page. 

Unconformities Continued.

within Vermilion series ............ 181,182

Willison . ... ._ .. . 182 

Uniformity, law of ...................... 513-514

Upham, on the Minnesota valley... 121 

on Minnesota...................... 122,123

onquartzites of Minnehaha county,

Dakota................. ... . 12*

Utah, literature of................ -.- 286-29ti

Urgliinmerschiefer, Lossenon...... 52C

Urgneiss, Lessen on ..._..._. . 525 

Uriconian, Callaway on.. - ..... 525

Ur thonschiefer, Lossen on... . 526

V.

Van Hise, on relations of Huronian and

Laurentian ....... ..... .... 44-46

on central Wisconsin ........ .... 116

on quartz enlargements _.. _ 140 

on iron ores of Penokee-Gogebic

district............................ 148-149

on the Penokee series............... 150-154

on unconformity between lower and

upper Huronian............. . 154-155

on the Menominee district ......... 156

on Menominee and Felch mountain

districts .......................... 156

on Black hills...... ....-_..-------- 259-260

on Missouri._.._............ 264-265

on Laramie and Medicine Bow

ranges................ . . 275-276

on Uinta mountains ...._._.... 289

on Wasatch mountains ._....._. 294-295

on Qtiartzite mountains . ___ _ 320-323 

onAdirondacks...................... 398-399

Vanuxem, en New York..... ....387,388,389-390

on Frankl in, New Jersey _........ 399

on Primitive......................... 470

Vennor, on Hastings county............28-29,30

on Laurentian..............28,29,30,31,33,38

on sou them New Brunswick...... 23i

on unconformity in Laurentian.... 471

on Hastings series................... 489,498

Vermilion, conformable with Keewatin,

N.H.Winchell on............... 129

A. and N. H. Winchell on ........... 169

Vermilion district, iron ores of......... 171,172

Vermilion range, A. H. Chester on.._ 123 

N.H.Winchell on................... 123-124

Vermilion series, unconformably below

Animikie.......--...--...--.. 181,182

unconformity within........._.... 181,182

relations to original Huronian..... 185-186

Vermont, literature of........ _...... 355-361

Virgin mountains, Marvine on. _..... 296

Virginias, literature of the ............ 416-418

W.

Wadsworth, indebtedness to.. _.. _ 17

on iron and copper districts of lake

Superior..................... . 86-87

on fossil from lake Superior. _.... 88

on upper peninsula of Michigan. _ 102 

on lake Superior sandstone. ....102,103,158,

159,160 

on Keweenawan.. ._... .. 161

Page. 

Wadsworth Continued.

on lake Superior succession _.... 163,165

on lake Superior eruptives.._.... 173

on unconformity within Huronian. 180 

on iron ores of lake Superior.... 170,171,172

on Massachusetts_._ __.... 367,369

on pre-Cambrian succession 454-457,5:.0,511 

on Azoic_.._.._.._........ 470

on origin and stratigraphy of Archean._..__._...._..-.. 481

on stratigraphy of Archeau _. 488 

onpre-Potsdamlife ..._......_.. 491-492

Walcott, indebtedness to........ _..... 16,17

on fossils in Newfoundland Algonkian.............................. 251,492

on Newfoundland ................... 251

on Olenellus of Newfoundland...... 251

0 on Texas............................1. 266-267

on Llano series....".......... ..... 269,504

on Wasatch mountains _ _...... 263,294

on Eureka series .._.. .__....-- 305

on Grand cany on.................... 329-330

on New England.......... .381,382,385,415

onAdirondacks .....-.....'.......... 398,508

on fossils of Grand canyon......... 492

on pre-Cambrian succession._.... 468-469

on Algonkian._..____.......... 469

on upper limit of Algonkian ....... 495-496

Wasatch mountains, Fortieth Parallel

Survey on..__...__...... 297

Archeau Of.......... .......298-299,475,487

Algonkian of...... ................ 299,505

literature of ......................... 289-295

Washington, literature of ....... _.... 337

Wet mountains, literature of........... 313-314

Whiteonlowa, Minnesota, and Dakota. 119 

White mountains, Rogers on........... 350

Whitney, indeb tedness to. _.. __.... 17

on Keweenaw point...... _.._..73,76-77

on 1'Anse,Michigan ..__..._ _....74,76-77

on iron ore of Michigan............. 75

on lake Superior __.........-.-- 75,76

on the copper lands of lake Superior............................... 78-79

on iron region of lake Superior .... 79-82

on Azoic of lake Superior.......... 82-85, 167

on lake Superior sandstone....82,84,85,157,

158,160,16'-!, 165 

on iron ores of lake Superior....... 85,170

on Keweenawan..--._._ .__ 161 

on lake Superior succession........ 16S; 165

on lake Superior eruptives...... _ 173

on unconformity within Huronian. 179 

on lake Superior syncline ...... _ 196

on Missouri.......................... 261-262

on California ........................ 335,341

on pre-Cambrian succession- 454-457,51C, 511 

on Azoic......_.__.._........ 470

on origin of Archean.._..._.... 481

on stratigraphy of Archean. _. _ 488 

on pre-Potsdam life ................. 491-492

Whittlesey, on northern Wisconsin. ..83-84,106 

on Laurentian and Huronian of lake

Superior......................... 86

on lake Supei-ior sandstone._ _. 158 

on Laurentian of lake Superior. _ 168
INDEX. 549

PaSe.

Wight, on lake Superior sandstone.... 109-110

Wilkins, onLaurentian....._._..... 31-32

Williams (C. P.), on Portage lake trap

range..____................... 8fi

Williams (George H.), indebtedness to. 16,17 

on the greenstones ol Marquette

and Menominee districts _. 149 

on lake Superior succession ........ 105

on lake Superior eruptives ......... 173

on New Hampshire_......_._. 355

on Cortlandt series, New York . 397 

onAdirondacks...................... 398-399

on Maryland..._..._...._.... 411,415

Willis, indebtedness to.................. 16.17

on northeastern Minnesota......... 145

on lake Superior succession........ 167

on unconformity within Vermilion

series...........:............-...- 182

Winchell, Alex., on Huronian..-..-.41,42,43,47 

on upper peninsula of Michigan.... 89-90,

101-102 

on northeastern Minnesota........ 124-125,

127-128,131 

on lake Superior succession ........ 166

on Laurentian of lake Superior .... 168

on lake Superior Huronian......... 169

on Vermilion .._..._....._.... 169

on relations of Algonkian and Archean......................... 177,178,192

on xinconformity between Animikie

and Vermilion series.._...... 181

on unconformity within Huronian. 179,180,

182,184-185 

on definition of Huronian........... 193

on Marquettian...................... 193

on relations of granites and schists 383 

on origin of Archean __._........ 479,480

Winchell, H. V., on northeastern Minnesota..... ..................._. 128

on the iron regions of Minnesota... 130 

on iron ores of Minnesota......131,131-132,

132-133 

on the Saganaga syenite............ 133

on Vermilion district iron ores..... 172

Winchell, N. H., on Huronian..........40-41,44

on upper peninsula of Michigan... 101 

on Minnesota.................119-120,120-123

on the Minnesota valley ........... 120

on the Cupriferous series of Duluth 120-121

Page. 

Winchell, N. H. Continued.

on northeastern Minnesota .120,121,122,123, 

125-126,126-127,129-130,132 

on the Cupriferous series of Minnesota.................. -------- 122

on Mesabi and Vermilion ranges... 123-124 

on crystalline rocks of the northwest.............................. 124

on fossil in quartzite of Minnesota. 124,492 

on iron ores of Minnesota....... 125-126,131,

131-132,13:M 33 

on a Primordial quartzite ......... - 128-129

on epochs of basic eruption in Minnesota.................._....... 131

on lake Superior sandstone _...... 158

on Keweenawan.._...._....... 162

on lake Superior succession........ 166

on lake Superior Laurentian....... 168

on lake Superior Huronian........ 169

on Vermilion ........................ 169

on Vermiliou district iron ores..... 172

on relations of Algonkian and Archean..........................177,178,192

on unconformity within Huronian. 180,182 

on unconformity between Animikie

and Vermilion series ............ 181

on definition of Huronian.. _...... 193

on fossils In Sioux quartz! tes .. _. 194 

on position of Animikie series...... 194

on position of Keweenawan ........ 194

onBlackHills....................... 257

Wind river mountains, literature of... 279-280 

Wisconsin, literatureof................. 105-118

Wislizenus, on Front range ............ 314

Wolft, onHoosac mountain, Massachu:

setts .......................372-374,415

on New England..................... 382,385

Wooster, on northern Wisconsin. _.. 118 

on lake Superior sandstone ......... 158

Wright, on the upper peninsula of Michigan.............................. 97

on the Penokee district.............. 11?

on the Menominee district _....... 110

on lake Superior succession........ 161

Wyoming, central and western, literature of..._...................... 277-281

Huronian of......................... 281-282

Laurentian of ....................... 281-282

Prozoicof............................ 281-282

Wyoming range, literature of.....__ 280