~-------------------~------------------------~--~ 

· DEPARTMENT OF THE INTERIOR 

FRANKLIN K. LANE, Secretary 

UNITED STATES GEOLOGICAL SURVEY 

GEORGE OTIS SMITH, Director 

PROFESSIONAL PAPER 120 

SHORTER CONTRIBUTIONS TO 

GENER.AL GEOLOGY 

1918 

DAVID WHITE, CHIEF GEOLOGIST 

WASHINGTON 

GOVERNMENT PRINTING OFFICE 

1919 
'I 

DEPARTMENT OF THE INTERIOR 

FRANKLIN K. LANE, Secretary 

UNITED STATES GEOLOGICAL SURVEY 

GEORGE OTIS SMITH, Director 

Professional Paper 120 

SHORTER CONTRIBUTIONS TO 

GENERAL GEOLOGY 

1918 

DAVID WHITE, CHIEF GEOLOGIST 

WASHINGTON 

GOVERNl\IENT PRINTING OFFICE 

1919 

CONTENTS. 

l The letters in parentheses preceding the titles are those used to designate the papers ·ror advance publication.] 

Page. 

(A) New determinations of c·arbon dioxide in water of the Gulf of Mexico, by R. C. Wells (published June 20, 

1918) ....................................................................... ·....................... 1 

(B) Geology of northeastern Moritana, by A. J. Collier (p{lblished Dec. 12, 1918).............................. 17 

(C) Deposits of Claiborne and Jackson age in Georgia, by C. W. Cooke and H. K. Shearer (published June 4, 1918). 41 

(D) rrhe structure and stratigraphy of Gravina and Revillagigedo islands, Alaska, by Theodore Chapin (published Aug. 22, 1918)................................................................................ 83 

(E) rl\vo lamprophyre dikes near Santaquin and Mount Nebo, Utah, by G. F. Loughlin (published June 14, 

1918) .................... · ... .-................................ · .................. ·..................... 101 

(F) Relations of late Paleozoic and early Mesozoic formations of southwestern Montana and adjacent parts of 

Wyoming, by D. D. Condit (published Oct. 21, 1918)................................................ 111 

(G) New graphic method for determining the depth and thickness of strata and the projection of dip, by H. S. 

Palmer·(published Aug. 21, 1918).................................... ... . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 

(R) A contribution to the geology of northeastern Texas and southern Oklahoma, by L. W. Stephenson (published Nov. 22, 1918)............................................................................... 129 

(I) Some American Cretaceous fish scales, with notes on the classification and distribution of Cretaceous fishes, 

by T. D. A. Cockerell (published April 24, 1919)..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 

Index.................................................................................................... 203 

ILLUSTRATIONS. 

PLATE I. Map of northeastern Montana showing the distribution of the geologic formations.................... 18 

II. A, Gorge of Rock Creek, Valley County, Mont.; B, Grain field near Scobey, Mont.; C, Camp in the foothills of the Little Rocky Mountains, Phillips County, Mont...................................... 20 

III. A, View up the valley of Cottonwood Creek, Phillips County, Mont.; B, Badlands of Bearpaw shale 

near Lisn1as, ~{on t. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 

IV. A, Lower part of the Lance formation, showing spherical concretions; B, Arenaceous sandstone showing eolian cross-bedding........................................................................ 32 

V. A, Pinnacle of soft sandstone of Lance formation; B, Erosion form of Lance formation . . . . . . . . . . . . . . 33 

VI. A, View south across the Missouri Valley, Valley and Dawson counties, Mont.; B, Gravel pit at Wolf 

Point, Mont.; C, Loglike concretion in Fort Union formation.................................... 36 

VII. Map showing distribution of the Eocene formations of Georgia..... . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . 50 

VIII. A, Wave-cut bench, Dall Bay, Gravina Island, Alaska; B, Conglomerate, Blank Inlet, Gravina Island; 

C, Slate and graywacke, Blank Inlet, Gravina Island; D, Anticline on Vallenar Bay, Gravina Island. 88 

IX. Map showing outcrops of Phosphoria and equivalent formations in southwestern Montana and adjacent 

parts of " 7yoming ................... :......................................................... 112 

X. Stratigraphic sections in southwestern Montana and Yellowstone National Park.................... 114 

XI. A, Canyon of Indian Creek, Madison Range, Mont.; B, Principal peak in Snowcrest Range, Mont... 116 

XII. A, View westward along crest of Centennial Range from1 point near Montana principal meridian; 

B, Shaly calcareous beds along crest of Centennial Range, equivalent to Dinwoody formation of 

Wyoming. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 

XIII. A, North face of Bannock Peak, Yellowstone Park; B, Upturned beds on south slope of Owl Creek 

Mountains, Wyo., near Shotgun Creek, T. 7 N., R. 1 E............ . . . . . . . . . . . . . . . . . . . . . . . . . . 118 

XIV. Alinement diagram for computing deptl;l.......................................................... 124 

XV. Alinement diagram for computing thickness...................................................... 126 

XVI. Alinement diagram for computing projected dip.................................................. 128 

XVII. Geologic map of part of northeastern Texas and southern Oklahoma............................... 130 

XVIII. Correlation table showing the relation of the subdivisions of the Comanche series in Grayson 

County, Tex., to the formations of the same series in other parts of Texas and Oklahoma........ 134 

XIX. A, Trinity sand and loose slabs of Goodland limestone at Rock Bluff (Old Marshall Bluff) on Red 

River 8! miles northwest of Denison, Grayson County, Tex.; B, Goodland limestone on Little 

Mineral Creek in northern Grayson County, Tex............................................... 136 

XX. A, Top of Kiamichi clay, overlain by limestone member of Duck Creek formation, in bluff above 

Tl~omson Ferry, Red River, 11 miles northwest of Denison, Grayson County, Tex.; B, Slabs of 

Gnjphaca-bearing impure limestone from the upper part of the Kiamichi clay at the locality shown 

inA .... :.................................................................................... 138 

III 
IV CONTENTS. 

PLATE XXI. A, Earthy facies of the lower part of the Fort Worth limestone on the Oklahoma side of Red 

River, at the Missouri, Kansas & Texas Railway bridge 5 miles north of Denison, Grayson 

County, Tex.; B, Fossil fucoids (?)on the under side of a slab of Fort Worth limestone, at 

Page. 

the locality shown in A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 

XXII. A, Upper part on the Weno clay in the east bank of Washita River at the Frisco Railroad 

bridge 21 miles west of Platter, Bryan County, Okla.; B, Weno-clay in a cut of the Frisco 

. ~ailroad a mile north of the station at Denison, Grayson County, Tex................... 140 

Xxiii. A, Main Street limestone in a cut of the Missouri, Kansas & Texas Railway 3 miles west of the 

station at Denison, Grayson County, Tex.; B, "Quarry" limestone, underlain by the Weno 

clay, in'a cut of the Frisco Railroad three-quarters of a mile north of Denison, Grayson 

County, Tex........................................................................ 141 

XXIV .. A, Woodbine. sand. in a cut on the Missouri, Kansas & Texas Railway it miles west by 

south of the station at Denison, Grayson County, Tex.; B, Main Street limestone under-

. ·lain by the Pawpaw sandy member of the Denison formation near the subway south of 

the Missouri, Kansas & Texas Railway station at Denison, Grayson Connty, Tex . . . . . . . . 112 

XXV. A, San'd and. Clay 'o£ the Woodbine formation at Hyatts Bluff, on Red River' 5 miles northwest of Ravenna, Fannin County, Tex.; B, Ferruginous sand of the Woodbine formation 

in the ·sherman road, .2 miles southwest of Denison, Grayson County, Tex............... 143 

XXVI. A, Topography in the hilly area underlain by the Woodbine sand 1t miles southwest of 

Denison, Grayson County, Tex.; B, A detail of topography in a small branch valley underlain by the Woodbine sand, 1! miles southwest of Denison, Grayson County, Tex....... 144 

XXVII. A, Contact between the Eagle Ford clay and the Austin chalk in a quarry of the Texas Port-

. land Cement Co., 3 miles west of Dallas, Tex.; B, "Fish-bed conglomerate" (?) in the 

bed of a branch 3 miles south of Ravenna, Fannin County, Tex ......... _.............. 145 

XXVIII. A, Annona tongue of Austin chalk in the bank of a creek 5! miles west of Leonard, Fannin 

County, Tex.; B, Building-stone facies at top of Annona tongue of Austin chalk in an 

abandoned quarry 3 miles south of Honey Grove, Fannin County, Tex. . . . . . . . . . . . . . . . . 148 

XXIX. A, Basal beds of the Pecan Gap chalk in a cut of the Gulf, Colorado & Santa Fe Railway half 

a mile east of the station at Pecan Gap, Delta County, Tex.; B, Fossiliferous concretionary 

layer of calcareous sandstone in the Wolfe City sand in a cut of the Gulf,. Colorado & Santa 

.. Fe Railway 1! miles east by north of Wolfe City, Hunt County, Tex..................... 15'1 

XXX. A, Structure section across the Preston anticline from a poi:pt near the northeast corner of the 

Denison quadrangle to Sherman, Grayson County, Tex.; 13., Structure section from Ladonia, 

Fannin County, to a point near Farmersville, Collin County, Tex.; C, Gener~lized diagrammatic section showing the physical and age relations of the formations of the Gulf 

series in northeastern and central Texas . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . 155 

XXXI-XXXVII. Cretaceous fish scales ................................................ · .................... 189-202 

FIGURE ·1. Curve showing variation of loosely combined carbon dioxide in surface sea water with temperature. 13 

· 2. Sketch map of the geology ofT. 25 N., Rs. 25 and 26 E. principal meridian, Mont................. 21 

3. Section of the laccolith of the Little Rocky Mountains, Mont..................................... 23 

4. Section in badlands south of Wood Mountain, Saskatchewan; Canada, showing the relation of Fort 

Union formation, upper part of Lance formation, lower part of Lance formation, and :,3earpaw 

shale....................................................................................... 31 

5. Generalized sections of Fort Union and Lance formations, showing their relation to the Bearpaw 

shale from its outcrop northwest of Opheim to Plentywood, Mont.; north of Missouri River from 

. Brockton to the Dakota line; and in the Larb Hills, in T. 24 N., R. 33 E................ . . . . . . . .. 34 

6. Relations of the Bowdoin dome to· the structure prevalent in the Little Rocky Mountains, Mont... 38 

7. Section from Grovetown to Griffin's Landing, Savannah River, Ga................................ . 50 

8. Diagram showing the relations between the Ocala limestone and the Barnwell formation.......... 53 

9. Section from Rich Hill, Crawford County, to the mouth of Gum Creek, Crisp County, Ga.......... 53 

10. Map of southeastern Alaska showing position of Gravina and Revillagigedo islands................. 83 

·11. Geologic sketch map of Gravina Island and a part of Revillagigedo· Island; Alaska................. 84 

12. Structure section across Gravina and Revillagigedo islands, Alaska............................... 87 

13. Geologic map of the Santaquin and Mount Nebo region, Utah ................. ~ .... ,.............. 102 

14. Diagrammatic cross section from Idaho-Montana State line ·near Yellowstone Park to the vicinity 

of Helena, Mont ............................ · ................................. :............... 114 

· 15. Diagram showing three cases in computing depth................................................. 123 

16. D;iagram showing three cases in computing thickness .................................... _. . . . . . . . 124 

17. Diagram for deviation of formula for projected dip .................................. : . . . . . . . . . . . . 125 

18. Diagram showing three stages in derivation of principle of the alinement diagr~m.... .............. 126 

19. Diagram for derivation of the interrelation of M1, M2, M3 , D1, and D2 •••••••••••••• :.............. 127 
SHORTER CONTRIBUTIONS TO GENERAJ.J GEOLOGY, 1.918.· 

NEW DETERMINATIONS OF CARBON DIOXIDE IN WATER .OF THE GULF 

OF MEXICO. 

By RoGER C. WELLS. 

INTRODUCTION. how nearly saturated the water is with respect 

Although the carbon dioxide in sea water to that substance. 

is the subject of a very extensive literature I have been enabled to make the determina 

and many determinations of it have been tions described in this paper through the inter 

n1ade, recent advances in ge~chemistry have est and cooperation of T. W. Vaughan, of 

brought out new relations that require further the United States Geological Survey, and 

determinations in order to show the con- H. F. Moore, of the Bure~u of Fisheries 

nection, if any exists, between the history of Mr. Vaughan pointed out the need of such 

the water, its temperature, its geographic determinations, particularly for American 

location, the life it contains, and its saturation waters, and Mr. Moore authorized the collection 

with calcium and magnesium compounds. In of the samples, which were actually collected 

1914 Clarke and Wheeler/ in a paper.on crinoid by W. w.· Welsh and shipped in "citrate of 

skeletons, pointed out for the first time that magnesium" bottles to the chemical laboratory 

the proportion of magnesium carbonate in of the Geological Survey for analysis. It is a 

crinoids is in some way dependent on tempera- great pleasure to express appreciation for the 

ture. This observation led to the publication assistance offered by all those who helped to 

of a number of papers presenting facts and make the study possible. 

theories bearing on the subject. 2 There is no ·question that the water of the 

Even earlier the investigations of Vaughan s Gulf of ~1:exico 1s . essentially similar to that 

on coral reefs and those of Branner 4 on the of the open ocean. An analyais of the salts 

stone reefs of Brazil had led to the consideration 1n water off Loggerhead Key, near Florida, 

of physical factors in the deposition of calcium made by George Steiger in the chemicallaboracarbonate in certain localities. Johnston has tory of ~he United States Geological Survey, is 

pointed out that the deposition of calcium shown Ill Table 1, together with Dittmar's 

carbonate by organic agencies may be closely mean of 77 analyses of ocean water. 

related to the inorganic factors that determine TABLE I.-Analyses of oceanic salts.a 

'Clnrkc, F. W., and Wheeler, W. C., The composition of crinoid 

skeletons: U. S. Ocol. Survey Prof. Pnpcr 90, pp. 33-37J 191.'>. 

D Wells, R. C., '!'he solubility of magnesium carbonate h1 natural waters: 

Am. Chcm. Soc. Jour., vol. 37, pp. 1704-1707, 1915. Johnston, John, Tho 

solubility-product constant of calcium and magnesium carbonates: 

1dom, pp. 2001-2020. Wells, n. C., The solubility of calcite in water 

ln. contnct with tho atmosphere, and its variation with temperature: 

Washington Acad. Sci. Jour., vol. 5, pp. 617-622, 1915. Johnston, John, 

and Wllliamson, E. D., Tho complete solubility curve of calcium carbonate: Am. Chern. Soc. Jour., vol. 38, pp. 975-983, 1916. Johnston, 

John, Merwin, H. E., and Williamson, E. D., The several forms of 

cnlcium carbonate: Am. Jour. Sci., 4th sor., vol. 41, pp. 473-512,' 1916. 

Johnston, John, and Williamson, E. D., Tho rOle of inorganic agencies 

In tho deposition of calcium carbonate: Jour. Geology, vol. 24, pp. 729-

749, 1916. 8 Vaughan, T. W., The present status of the investigations of the origin 

of barrier coral reefs: Am. Jour. Sci., 4th sor., vol. 41, pp. 131-135, 1916. 

Sco also Carnegie Inst. Washington Pub. 133, pp. 173-177, 1910; Pub. 182, 

pp. 69-iS, 191•!; Year Hook 14, p. 222, 1916, and Pub. 213, p. 227, 1918. 

4 Branner, J. C., Stone roofs on tho northeast coast of Brazil: Ocol. 

Soc. Amcrlctl Hull., vol. 16, pp. 1-12, 1905. 

Cl .............................. . Br ............................. . S04 •••••••••••••••••••••••••••••• 

003 •••••.•••.••••••••••••••••••••• 

Na .............................. . K ................................ . Ca ............................. . ~1g ............................. . 

1 2 

55.24 

.17 

7.54 

. 34 

30. 80 

1. 10 

1. 22 

3. 59 

100.00 

55. 29 

.19 

7. 69 

. 21 

30. 59 

1. 11 

1. 20 

3. 72 

100.00 

a Clarke, F. W., The data of geochemistry, 3d cd.: U.S. Goo!. Survey 

Hull. 616, p. 123, 1916. 

1. Salts in water of GulfofMexico; George Steiger,analyst. 

2. Salts in ocean water, mean of 77 analyses; W. Dittmar, analyst. 

1 
2 SB:ORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

Although the analysis of Gulf _water cited 

in this table shows the essential similarity 

of the water to sea water, it seems likely 

that the total carbon dioxide has been stated 

as 003 • 'The value stated amounts to 0.091 

gram C02 per liter, which is about that of 

ordinary sea water. Dittmar's figure, on the 

other hand, does not account for all the C02 

normally present in sea water. It is generally 

believed that carbon dioxide, in so far as it cqnstitutes part of the salts in sea water, is present 

both as c·arbonate and as acid carbonate, 

commonly termed "bicarbonate." It was. to 

ascertain the relative proportions of carbonate 

and bicarbonate in the water that the determinations recorded in this paper were made. 

Such determinations have also been made by 

Dole/ by titration methods, pn water from 

Southwest Channel, Tortugas, Fla. Dole's 

results are as follows: 

Gram C02 as HC03 : per liter. 

Highest. . . . . . . . . . . . . . . . . . . . . . . . .. 0. 088 

Lowest......................... . 059 

Mean ............ · ................ 069 

C02 as C03 : 

Highest. . . . . . . . . . . . . . . . . . . . . . . . . . 022 

Lowest ........................ ~ . 011 

Mean........................... . 017 

Total C02 : 

Highest. . . . . . . . . . . . . . . . . . . . . . . . . . 099 

Lowest......................... . 080 

Mean ........... ,............... . 086 

Titration methods, however, have been 

called in question by Johnston/ and for that 

reason it seemed especially desirable to apply 

new methods where possible. The present 

contribution by no means exhausts the subject. 

Further determinations are needed in connection with the alkalinity of the water determined 

at the source. 

DEFINITION OF TERMS. 

. Much of the haze that has long befogged the 

subject of the. carbonates in sea water is due to 

the different meanings given to the same terms 

by different investigators. It is surprising 

how tenaciously old terms persist in spite of 

well-proved facts warranting their abandonment. Some of these terms are so indefinite 

1 Dole, R. B., Some chemical characteristics of sea water at Tortugas 

and around Biscayne Bay, Fla.: Carnegie Inst. Washington Pub. 182, 

p. 73, 1914. 

2 Johnston, John, Determination of carbonic acid, combined and free 

in solution, particularly in natural waters: Am. Chern. Soc. Jour., vol. 

38, p. 947, 1916. 

that they convey no exact meaning unless 

they are repeatedly defined by the author who 

uses them. The word "salinity," for example, 

is used by some writers to include only part of 

the salts that exist in sea water and by others 

to include them all. The word " alkalinity" is 

used by some as a measure of the combined 

carbonate and bicarbonate concentration expressed in the same unit, and by others to indicate the hydroxide or hydrogen ion concentration. There are many modes of attack in ~this 

problem, but nearly every one involves some 

theory, so that it becomes· most necessary to 

keep clearly in view how much is fact and how 

much is theory and i1ot to confuse the two so 

that neither is of ~ny assistance. 

In the present paper sea water is held to be 

a " phase " in the sense of the phase rulethat is, a liquid capable of dissolving certain 

solids and gases up to the point of "saturation." Carbon dioxide is one of the gases that 

can thus be dissolved in sea water, and the 

determinations made (see Table 2) give the 

total carbon dioxide that can be extracted from 

the water after the addition of acid-that is, all 

the carbon dioxide that exists in the water in 

anvform. 

As already stated most of tlie carbon dioxide 

in sea water is commonly considered to be 

present as bicarbonate and carbonate, thus 

constituting the acid radicles of corresponding 

salts. Thus practically all the dissolved matter 

in sea water can be thought of as a group of 

salts the sum of whose basic radicles is chemically equivalent to the sum of their· acid radicles. This equivalence holds very closely for 

the analyses cited in Table 1 when the various 

forms in which carbon dioxide is cmnbined are 

correctly stated. Nothing leads to greater 

confusion, however, than to attempt to make an 

arbitrary combination of the various acid and 

basic constituents determined by analysis, 

and for this reason it is well to realize that such 

an expression as "the solubility of calcite in 

sea water" does not imply that calcium carbonate exists as such in sea water any more 

than that carbon dioxide exists as such, although both substances are doubtless present 

in these forms to some extent. 'When such 

compounds are added to sea water they react 

with other substances and enter into the complex kinetic equilibrium. that exists in the 
CARBON DIOXIDE IN WATER OF THE GULF OF MEXICO. 3 

water between all the salts and their ions, poured into a graduated 250 cubic centimeter 

hydrates, and hydrolytic products. The single flask and then into the distilling flask, and the 

worcl "carbonate" will therefore express the 'boiling was begun immediately. The results. 

group constituting the carbonat.e radicle (CO~), ,obtained are stated in Table 2. 

which would have to be taken in the form of a The locations given in Table 2 correspond to 

salt with the various other salts to make up an 'the following station numbers of the Bureau of 

artificial ·sea water. ·The term "bicarbonate" Fisheries: 

will have a similar meaning. The chemical Lat. 29° 38' N., long. 87° O' ,v., station 10447. 

symbols for these radicles will be COs and Lat. 29° 53' N., long. 87° 7' W., station 10448. 

IIC09 • \Vhen ions are meant the symbols Lat. 30° 5' N., long. 87° 12' W., station 10449. 

will bear additional signs for the electric 4 miles northwest of Pensacola Light, station 1.0450. 

chru:ges, thus: COs- and IIC03-. The same Sample 1, obtained near Fowey Rocks Light, 

sy:mbols inclosed in brackets are generally outside Biscayne Bay, Fla., was a portion of 

used to represent concentrations in gram water collected at regular intervals between 

n1olecules, or Inols, per liter, thus: [COs] or July 26 and August 3, 1915/ and had stood for 

[C03 -]. part of the time to April, 1917, in a green glass 

TABLE 2.-Total carbon diox·ide in samples of water from the Gulf of :Mexico. · 

Sample 

No. Location. 

1 Lat. 25 ° 351 N., long. 80° 6' W ................................ . 

2 Lat. 29° 38' N., long. 87° 01 W ................................ . 3 ..... do ...................................................... . 4 ..... do ...................................................... . 5 ..... do ........................................... · ........... . 6 ..... do ........................................................ . 

7 Lat. 29° 53' N ., long. 87° 71 W ................................ . 8 ..... do ...................................................... . 9 ..... do ...................................................... . 10 ..... do ...................................................... . 11 .. · ... do ...................................................... . 

12 Lu.t. 30° 51 N., long. 87° 12' W ................................ . 13 ..... do ...................................................... . 

14 4 miles northwest of Pensacola Light .......................... . 15 ..... do ...................................................... . 

Depth. 

Meters. 

0 

0 

50 

100 

150 

210 

0 

25 

50 

100 

130 

0 

20 

0 

10 

Temperature. Chlorine. Total C02 . 

o C. 

18.9 

19.4 

18.5 

13.3 

10.2 

20.0 

20.1 

19.6 

18.2 

. 15.8 

18.3 

.18.4 

16. 7 

16.4 

Grmns per Gram per 

liter. liter. 

20.37 0.106 

20.21 .093 

20.23 .092 ...................... ............. 20.20 .099 

19.94 .190 

20.52 .092 

20.39 . 092 

20.40 .094 

20.52 .100 

20.40 . 098 

20.48 .095 

20.38 .092 

18.34 . 088 

19.66 . 092 

DETERMINATION OF TOTAL CARBON DIOXIDE. 

The total carbon dioxide was determined by 

boiling 250 cubio centimenters of the water, 

after the addition of hydrochloric acid, for 

10 to 15 minutes, driving out the gas with a 

stream of pw·e air and collecting it in weighed 

tubes containing soda lime, the apparatus 

used being that generally employed in the 

analysis of carbonate rocks. 1 The water had 

been preserved and shipped, after collection, 

in "citr~te of n1agnesium" bottles, with only a 

very sn1all bubble of air space. After the 

bottle was opened a portion of the sarn.ple was 

bottle with considerable air space. The result 

for the total C02 in this sample may have 

been affected by exposure of the sample before 

analysis. The otlier samples were collected 

in January, 1917, preserved in "magnesium 

citrate" bottles with practically no mr space, 

and analyzed in April, 1917. 

1 Hillebrand, W. F., Tho analysis of carbonate and silicate rocks: 

U. B. Goo!. Survey Dull. 422, p. 180,1910. 

The results seem to show . that the total 

content of carbon dioxide increases slightly 

with increase of depth. The· average content 

for the.samples of surface waters is 0.092 gram 

per liter. The average for all samples is 0.094 

gram per liter. Naturally .it is interesting to 

2 Dole, R. D., and Chambers, A: A., Salinity of ocean water at Fowey 

Hocks, Fla:: __ CaT~egie lust. Washington Pub. 213, p. 284, 1918. 
4 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

compare these figures with those obtained by 

other investigators. · 

the total carbon dioxide is a little higher than 

in intermediate waters, for reasons that are 

discussed on page 11. The average for the 

bottom waters is O.i01; that for the interDittmar gives only four determinations on 

surface waters that are comparable with these, 

and aU of them involve determinations of the 

"loosely combined" carbon dioxide, which 

were made by J. Y. Buchanan by a method that 

is not generally considered to yield exact results. However, they are as follows: 1 

mediate waters is 0.095. · 

Sample 

No. 

265 

1573 

1581 

1687 

Tornoe found the average in 78 analyses of 

sea water to be 0.096 gram of carbon dioxide 

per liter, and results of the same order were obtained by N atterer. 2 Ruppin 3 found in the 

TABLE 3.-Dittmar and Buchanan's determinations of total carbon dioxide in surface waters. 

Locality. Tempera- 002. ture. 

o C. 

Gram per 

liter. 

South Atlantic Ocean, lat. 22° 15' S., long. 35° 37' W .............................. 22.8 0. 106 

South Atlantic Ocean, lat. 23° 27'S., long. 13° 51' W .............................. 25. 1 . 099 

South Atlantic Ocean, lat. 19° 55'S., long. 13° 56' W ..................... · ......... 24. 7 . 093 

North Atlantic Ocean, lat. 21° 231 N., long. 31° 15' W .............................. 22.8 .092 

The results of the analyses of the 14 samples 

of Gulf water are in fair agreement with the 

four results of Buchanan's analyses of four 

samples of water from the surface of the 

North Sea, at a depth of 5 meters, 0.091 gram 

of carbon dioxide per liter, and at 460 meters 

0.095 gram. 

Estimates by Dole of the total carbon dioxide 

open ocean. in the Gulf water at Tortugas are gtven on 

TABLE 4.-Dittmar and Buchanan's determinat?:ons of total carbon dioxide in deep waters. 

SaiD.ple Locality. Depth. TemperaNo. 002. ture. 

Fathoms. 0 c. 

Gram per 

liter. 

21 North Atlantic Ocean, lat. 23° 101 N., long. 38° 42' W .................. B 2, 720 2.5 0.096 

66 North Atlantic Ocean, lat. 19° 411 N., long. 65° 71 W ................... B 3,878 ········-· .112 

120 North Atlantic Ocean, lat. 32° 54' N ;, long. 63° 22' W .................. B 2,360 2.4 .102 

283 South Atlantic Ocean, lat. 29° 351 S., long. 28° 9' W ................... 1,000 2.8 .109 

353 Indian Ocean, lat. 46° 46'S., long. 45° 31' W .................... : .... B 1, 375 2.0 .118 

378 Indian Ocean, lat. 60° 52'S., long. 80° 201 W ......................... B 1, 260 ·········· .128 

383 Indian Ocean, lat. 65° 42'S., long. 79° 49' W ......................... B 1,675 .......... .149 

(556) South Pacific Ocean, lat. 14° 7' S., long. 153° 43' E .................... B 2,450 2.2 .101 

594 West Pacific Ocean, lat. 5° 24'S., long. 130° 37' E .... ~ ............... 400 6.4 . 094 

791 North Pacific Ocean, lat. 11° 24' N ., long. 143° 16' E ................... B 4,475 1. 8 . 086 

912 North Pacific Ocean, lat. 36° 23' N., long. 174° 31' E ................... B 2, 775 1.6 . 090 

1221 South Pacific Ocean, lat. 32° 36'S., long.·137° 43" W ................... B 2,375 1. 7 .103 

1300 South Pacific Ocean, lat. 38° 7' S., long. 94° 4' W ....... : . ............ B 1,500 1.8 .102 

678 West Pacific Ocean, lat. 5° 47' N., long. 124° 1' E ..................... 50 25.4 . 081 

1270 South Pacific Ocean, lat. 39° 13' S., long. 118° 49' E ................... B 2,250 1.4 .100 

1313' South Pacific Ocean, lat. 38° 6' S., long. 88° 2' E ..................... B 1,825 1.8 .108 

1356 South Pacific Ocean, lat. 32° 50'S., long. 77° 61 W ..................... 50 12.0 .102 

1388 South Pacific Ocean, lat. 42° 43'S., long. 82° 11' W .................... B 1,450 2. 0 .112 

1405 South Pacific Ocean, lat. 48° 27'S., long. 74° 30' W .................... B 345 7.8 . 097 

1438 South Pacific Ocean, lat. 52° 45' S., long. 73° 461 W .................... B 245 7.8 .102 

1494 South Atlantic Ocean, lat. 35° 39'S., long. 50° 471 W .................. B 1,900 0.6 . 098 

1697 North Atlantic Ocean, lat. 26° 21' N ., long. 33° 37' W .................. B 2,965 3. 1 . 092. 

1707 North Atlantic Ocean, lat. 32° 411 N ., long. 36° 6' W ................... 400 9.8 . 091 

The results obtained by combining the data page 2, but it should be noted that Dole did 

of Dittmar and Buchanan for deeper waters not dire~tly determine the total carbon dioxide. 

are given in Table 4. Most of these· were 2 Clarke, F. W., The data of geochemistry, 3d ed.: U.S. Geol. Survey 

"bottom" waters (marked "B "), in which nun. 616, p. 144, 1916. 

a Ruppin, E., Die Alkalinitat des Meerwassers: Zeitschr. anorg. 

1 Challenger Rept., Physics and chemistry, vol. 1, p. 215, 1884. Chemie, vol. 66, p. 122, 1910. 
CARBON DIOXIDE IN WATER OF T'E;E GULF OF MEXICO. 5 

Dole also obtained figures ranging from 0.055 In 1916 I performed two experiments .w_ith 

to 0.109 in Biscayne Bay, the lowest being sea water to determine its total content of 

for water in Featherbed Bank, at 26.4° C., and carbon dioxide at two definite temperatures, 

he concluded from the salinities that evapo- 1° C. and 28° C., after prolonged agitation of 

ration was going on in the shallow water of the the water with outdoor air, an excess of calbay at the time his samples were taken. This cite also being present in the water. The mean 

action should also be accompanied by a loss partial pressure of C02 was 0.000318 atmosof carbon dioxide, as actually observed. His phere, according to my determinations, and 

average for the total carbon dioxide is 0.084 the two normalities found for C03 + HC03 were 

gram per liter. 0.00236 and 0.00196, respectively. The result 

.THEORETICAL AMOUNT OF CARBON DIOXIDE IN for total C02 at 1° C.\ was 0·101 gram per liter, 

SEA WATER. and that at 28° C. was 0.078 gram. These 

results agree essentially with those calculated 

If there are sources of carbon dioxide in the by the formula of Fox/ which gives 0.100 and 

deep sea and the circulation of the water is 0.075, respectively. 

slight, one might expect, theoretically, to find Fox's formula, expressed in the terms used 

very considerable concentrations of carbon in the present discussion, is 

dioxide in such water. The pressure of the 

water would hold far larger proportions of any 

gas in solution than could remain dissolved at 

atmospheric pressure or smaller partial pressures. As very little is known about the extent 

to which moving creatures transfer carbon 

dioxide from place to place, the regulation of 

the concentration at depth would appear to be 

governed chiefly by the supply of carbon dioxide and by the rate of circulation of the water. 

At the surface, on the other hand, there is a 

tendency toward an equilibrium between the 

water and the atmosphere in respect to carbon 

dioxide, which Schlosing believed to be the 

governing factor in determining the carbon 

dioxide content of the atmosphere. This 

el]_uilibrium can be studied in the laboratory 

and the results compared with those obtained 

by observations made in different parts of the 

ocean. 

The equilibrium referred to may also involve 

the solution or deposition of calcium carbonate. 

A water in contact with calcium carbonate 

should theoretically dissolve more carbon dioxide from the atmosphere than one without .access to calcium carbonate, but my own experiments on tlll.s. point indicate that sea water 

exposed to a normal atmosphere gives off carbon dioxide at all temperatures above the very 

lowest, so that under surface conditions sea 

water in and between the temperate zones must 

be regarded as saturated with calciun1 carbonate. Therefore, laboratory experiments 

dealing with the equilibrium at ordinary temperatures yield the same results in the presence 

and in the absence of calcium carbonate. 

() 

Total C02 (grams per liter) =~+pb 

where n=the normality of C03 +HC03 , a= 

value given in Table. 5, p=partial pressure of 

C02 in at·mospheres, and b =value given in 

Table 6. 

TABLE 5.-Values of "a" for a solution of normality 1 at 

different temperatures and partial pressures of C02 • 

p. oo. 20. 10°. 16°. 20°. '28°. 

-----------

0.0002 40.42 40.08 38. 70 37. 69 37.00 35. 64 . 0003 42.09 41. 79 40.58 39. 67 39.07 37.86 . 0004 43. 11 42.83 41. 71 40.87 40. 31 39. 19 . 0005 43. 77 43.51 42.47 41. 69 41. 17 40. 13 . 0006 44. 37 44. 15 43. 24 42.56 42. 11 41. 21 

TABLE 6.-Values of "b" for different salinities and temperatures. 

[Chlorine in grams per thousand.] 

Ternpera- 01=0. 01=2. 01=10. 01=18. 01=20. ture 

(o C.). 

--------- 0 3. 39 3. 34 3. 16 2.98 2. 93 

4 2. 91 2.87 2. 69 2. 53 2. 50 

8 2. 53 2. 50 2. 34 2. 18 2. 14 

12 2.21 2. 18 2.07 1. 96 1. 93 

16 1.95 1. 92 1.81 1. 70 1.67 

20 1. 73 1. 71 1. 63 1.56 1. 54 

24 1. 54 1. 53 1.47 1. 42 1.'40 

28 1. 38 1.36 1. 28 1. 21 1. 19 

1 Fox, C. J. J., On the coefficients of absorption or nitrogen and oxygen 

in distilled water and sea water and of atmospheric carbonic acid in sea 

water: Faraday Soc. Trans., vol. 5, p. 82, 1909. 
6 SHORT'ER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

COMPARISON OF RESULTS WITH EQUILffiRIUM Other data than this eomparison (see p. 5) 

CONDITIONS. incline me to the· view that surface sea water 

We are now in a position to compare the de- ·is .. generally fully l saturated with respect to 

terminations of the. total carbon dioxid~ ·in atmospheric conditions; if so, there is some 

the samples, of Gulf watter with those repre- small constant error in the determinations or 

senting equilibrium with the atmosphere. For in· one of the factors on which the comparison 

this purpose I shall use 0.000318 atmosphere is based. ' The most interesting feature 'of the 

for the average carbon dioxide content of the comparison is the fact that the deeper waters 

atmosphere. 1 The normalities required in the seem to-be as near!to an equilibrium with the 

calculation were determined as described· in ·atmoSphere, for their temperature, as the sursucceeding pages ·and are stated in Table 10: face waters. That being true, what is the 

The comparison is shown in Table 7.. · ·source of their car: bon dioxide 1 It seems diffiTABLE 7 .-Comparison of total carbon dioxide found in the Gulf waters with that representing equilibrium with the · · ·atmosphere. 

Sample 

No. Locality~ Depth. T 0 002 for 

empera- Total C 2 equilibture. found. rium. 

oc. 

Gram per 

liter. 

Gram per 

liter. 

2 _Lat. 29° 381 N., long. 87° 01 W ~ .......... · ...... -.- ........... . 

3 ..... do ............. ----·· ... ------··- .. -·------ .. -- ...... -·--

Meters. 

0 

50 

150 

210 

18. 9 

19.4 

0.093 0.094 . 092 .098 

g :::: :~~:::::: :::::·::: :::: :·: ::·:: :: ::·:::::·::::::: :::: :::·: :::::: 

13.3 . 099 .099 

10.2 .100 .100 

7 Lat. 29° 531 N., long. 87° 71 W .............. ~ .......... _ .... . 0 

25 

50 

100 

20.0 .. 092 . 095 

8 ..... do ........... -.... -.- ...... --.---.-.- .... ----.- .. ----.- 20. 1 . 092 . 094 

9 ..... do ......... -- .............................. -- ..... · .... . 19. 6 . 094 . 098 

10 ..... do ....................... -.- ......... -.. -... -.-- ... -- .·. 18.2 .100 . 098 

11 ..... do ........ .' .......... -... · ... -~:-.·_ ... :~.- ....... -....... . 130 15.8 . 098 . 099 

12 Lat. 30° 51 N., long. 87° 12' W .............................. . 0 

20 

18.3 .095 . 097 

13 ..... do .......... -- ..... -- ..... -.......... -- .. -- .. ---- .... -. 18.4 . 092 . 097 

14 4 miles northwest of Pensacola Light. .................... · .... · 0 

10 

16. 7 . 088 .091 

15 ..... do ....................... -- .............. -..... -...... . 16.4 . 092 . 097 

The agreement between the last two columns 

of Table 7 is striking. In content of C02 the 

Gulf waters appear to be very nearly in equilibrium with the atmosphere-so nearly that 

the probable experimental error in the determinations of the normality of 003 +HC03 

would account for a positive or negative difference between many of the figures in the two 

columns. The same might be said of an error 

in the carbon dioxide content of the atmosphere 

used in the calculations or in the other factors 

entering into the comparison. From the data 

of Table 7 I do not feel warranted in concluding 

that any of the waters is either saturated or 

unsaturated with carbon dioxide under atmospheric conditions, but all the samples are evidently very near the condition of equilibrium. 

1 Tho higher value, 0.000353, recently published by Kendall, is for 

laboratory air. See Kendall, James, The specific conductivity of pure 

water in equilibrium with atmospheric ca:rbon dioxide: Am. Chern. 

Soc. Jour., vol. 38, p. 1490, 1916. 

cult to account for this ·adjustment by assuming that portions of the water have corn.e from 

cold regions where they were in contact with 

the atmosphere and have transported carbon 

dioxide all that distance. A portion of water 

in passing from the polar regions might lose 

and gain carbon dioxide a number of times 

before arriving in the Gulf of Mexico. Has the 

water of the Gulf of :Mexico access to more 

immediate sources of carbon dioxide than the 

atmosphere 1 Where the facts .are so suggestive it is natural to seek for some hypothesis to 

explain them, and the most plausible one 

appears to be that living forms either carry or 

supply the carbon dioxide necessary to maintain eq uili bri urn. 

Even Dittmar's results for carbon dioxide in 

the cold bottom waters of the ocean (Table 4) 

are approximately equal to the requirements 

for equilibrium with the atmosphere, although 

0 
CARBON DIOXIDE IN WATER OF THE GULF OF MEXICO. 7 

a few of the individual determinations show 

variations in one ·direction or the other. Inasmuch as the figures given by Dittmar include 

Buchanan's determinations and as the other 

factors on which the above comparisons rest 

are -the work of many investigators, it must be 

admitted that the close approach of these 

waters to equilibrium with the atmosphere is 

really 'remarkable, as is also the fact that this 

relation is found in waters as deep as 3,000 

fathoms. It seems as if organic agencies must 

contribute carbon dioxide to these deep waters, 

fori tis difficult to see how currents in the ocean 

could possibly carry carbon dioxide from the 

surf ace in the colder regions to all the localities 

in the ocean that have been investigated and 

could produce by mere mixture samples approaching so closely the requirements for equilibrium. Buchanan 1 writes on this point: 

Down to nearly 2,000 fathoms life is still abundant; 

below this depth, however, the amount rapidly decreases 

till, at about 2,800 fathoms, it is, for carbonic acid producing purposes, practically extinct. 

The preceding discussion suggests that the 

conditions maintained by organic and biochemical activity in the ocean correspond almost 

exactly with the physico-chemical conditions 

of equilibrium between sea water and a normal 

atmosphere at the temperatures involved. 

DETERMINATION OF TOTAL CARBONATE AND 

BICARBONATE. 

The determination of total carbonate and bicarbonate is sometimes referred to as that of the 

"alkalinity" and sometimes as that of the total 

base balancing carbonate and bicarbonate. 

Following Dittmar, investigators generally assume that there is no free base in sea water and 

that acid is consumed solely in setting free carbonic acid from carbonate and bicarbonate. 

Tho determination mentioned was made by titration with 0.02 normal sodium hydrogen 

sulphate. Methyl orange may be used as indicator, but the determinations were in fact carried out with paranitrophenol. The results 

obtained in titrating depend somewhat on the 

end point selected. The final reaction in the 

neutralization is 

N ai-IC03 + N aHS04 = N a2S04 + H2COs 

From this reaction it is evident that the indicator used should not give an indication for 

Although carbonic acid is commonly considered 

'to exert no action upon methyl orange, it really, 

as has long been known, develops a marked 

shade of red, and on this fact depends Kuster's 

method of titrating to the same shade as that 

produced in water saturated with carbonic 

acid. 2 His method gives correct results with 

relatively concentrated solutions of bicarbonates. In the present case, however, the concentration of bicarbonate is very small and the 

solution is far from being saturated with carbon 

dioxide at the true end point. After neutralizing with acid sulphate there will be present 

about 0.004 7 gram of C02 for 50 cubic centimeters of sea water. Evidently, the proper 

end point is indicated by the color produced by 

this amount of C02 in the same volume of water 

as that finally present in an actual determination. Experiment showed that this amount of 

C02 effects a scarcely perceptible change in 

methyl orange. If titration is carried to the 

first perceptible change· in tint, or better, to a 

standard color produced by the amount of 

C02 known to be present, the acid used will 

correspond, as nearly as can be determined, to 

the total base balancing carbonate and bicarbonate. 

In the hope of obtaining better results with 

some other indicator than methyl orange the 

behavior of paranitrophenol was studied~ The 

indicator solution contained 1 gram in 250 

cubic centimeters of water. The tests made 

are shown in Table 8; 

TABLE B.-Comparisons of color in 50 .cubic centimeter 

solutions in casseroles. 

Solution. 

la. Distilled water .......... . 2a. Distilled water, 0.0047 gram 

C02, 4 drops indicator. 

Color. 

No color. 

Scarcely perceptible col- or at first; a faint color 

appears slowly on standing. 

3a. Distilled water, 1 drop in- ' Clearlyperceptiblecolor. 

dicator. 

1 b. Distilled water ....... ~ . . . No color. 

2b. A solution of neutral sea Scarcely perceptible colsalta (prepared by neu- or at first; a faint color 

tralizing the carbonates appears slowly on in actual sea water with standing. 

the calculated quantity 

of acid and boiling out 

the carbon dioxide), 

0.0047 gram C02, 4 

drops indicator. 

3b. Distilled water, 1 drop 

indicator. 

Clearly perceptible color. 

H200s but for the first excess of N aHS04'1 2 Kiistcr, F. w., Kritische Studien zur volumctrischcn Bcstimmung 

von karbouathaltigcn Alkalilaugcn und von Alkalikarbonaten: 

• 13uchanan, J. Y., Roy. Soc. London Proc., vol. 22, p. 483, 1874. Zeitschr. anorg. Chemie, vol. 13, p. 127, 1897. 
8 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

The shades of color produced by the indicator were found to depend considerably on the 

qufility of the distilled water used. Freshly 

boiled water, after cooling, is perceptibly more 

alkaline than water as it comes regularly from 

the still or water that has stood in the laboratory some time, on account of the difference in 

carbon dioxide content. Solutions made up as 

described under 2a and 2b were used as furnishing the standard color for the proper end 

point. For the greatest possible accuracy it 

would appear that the preparation of the standard should be deferred until after the determination of total C02 • It is possible that better 

results could be obtained in Nessler tubes than 

in casseroles, but the glass of certain Nessler 

tubes was found to be rather too soluble for the 

purpose. No error seemed to be introduced in 

the very weak solutions of C02 under investigation by working in casseroles, and the color 

· showed up well in diffused daylight. However, 

it is doubtful if the results obtained with paranitrophenol were more accurate than those 

obtained with methyl orange. 

As nearly as could be determined the titrations were significant to about 1 per cent of the 

quantities being titrated, so that the combined 

normality of carbonate and bicarbonate in sea 

water ought to be determinable within 1 per 

cent by this method. Practically, however, the 

attainment of such accuracy would probably 

require a number of titrations on each sample. 

As the small samples of water available for the 

determinations recorded in this paper did not 

permit more than two titrations, and some 

samples only one, any single result is probably 

not nearer the true value than 2 per cent. 

The solution of NaHS04 used for titrating 

the samples of sea water, to determine the total 

base balancing carbonate and bicarbonate, was 

standardized with a solution containing sodium 

carbonate and bicarbonate in essentially the 

same proportion and concentration as in sea 

water. In this way the conditions at the end 

point were similar in both the standardization 

and the determinations. The results obtained 

in the standardization are shown in Table 9. 

TABLE 9.-Standardization of NaHS04 solution with solu· 

tions of NaHC03 and Na2C03 • 

Na2C03 • NaHS04 • 

Normality NaHC03 • of 

NaHS04 • 

Gram. Gram. c.c. 0. 00794 .......... 0.00143 5. 89 0.0206 . 00794 .......... . 00143 5. 87 . 0207 . 00794 .......... . 00143 5.82 . 0209 . 00794 .......... . 00143 5. 81 . 0209 . 00794 .......... . 00143 5. 92 . 0206 . 00794 .......... .. 00143 5. 86 . 0207 

Mean ....... .............. ---------- . 0207 

The results of the titrations are shown in 

the fourth column of Table 10. They are expressed in terms of normality, a normal solu- ~ 

TABLE 10.-Determina.tions of carbonate and bicarbonate in water from the Gulf of :Afexico. 

Sample 

No. Locality. Tempera- C03+HC03 HC03 nor- 003 nor- ture (0 0.). normality. mality. mality. 

1 Lat. 25° 35' N ., long. 80° 61 W .................................... ~ 0.00268 0.0021 0. 0006 

2 Lat. 29° 38' N ., long. 87° 01 W............................. 18. 9 

3 ..... do................................................... 19. 4 . 00239 . 0018 . 0006 . 00250 . 0017 . 0008 

4 ..... do................................................... 18. 5 . 00242 ........... ····------ 5 ..... do................................................... 13. 3 . 00245 . 0020 . 0004 

6 ..... do................................................... 10. 2 . 00245 . 0021 . 0004 

71 Lat. 29° 53' N. 1 long. 87° 71 W............................. 20.0 

8 ..... do................................................... 20. 1 

. 00242 . 0018 . 0007 . 00239 . 0018 . 0005 

9 ..... do ........... :....................................... 19.6 . 00250 . 0018 . 0007 

10 ..... do................................................... 18. 2 . 00249 . 0020 .. 0005 

11 ..... do................................................... 15. 8 . 00249 . 0020 . 0005 

12 Lat. 30° 51 N., long. 87° 12' W .... ·.. . . . . . . . . . . . . . . . . . . . . . . . 18. 3 

13 ..... do .... •.............................................. 18. 4 . 00245 . 0019 . 0006 . 00245 . 0017 . 0007 

. 00230 . 0017 . 0006 . 00241 . 0018 . 0006 

14 4 miles northwest of Pensacola Light....................... 16. 7 

15 ..... do.................................................... 16. 4 

Mean, exclusive of No. 1. ................................... . . 00244 . 00185 . 00058 

I 
CARBON DIOXIDE IN WATER OF THE GULF OF MEXICO. 9 

tion being one containing 1 gram equivalent 

of reacting substance per liter-that is, as 

1nany gran1s as the molecular weight reduced 

to a univalent basis. As is mentioned on 

page 3, sample 1 had stood for most of the 

time from July, 1915, to April, 1917, in a green 

glass "acid" bottle with some air space. The 

other samples were collected in January, 1917, 

preserved in bottles with practically no air 

space, and analyzed in April, 1917. Without 

doubt it would have been better if the titrations 

could have been n1ade on shipboard immediately after the samples were taken. The high 

value of the carbonates in sample 11nay be due 

to attack :of the glass bottle. The figures for 

the other 14 samples may also be slightly high 

for the same reason, but if the difference between sa1nple 1 and the others represents the 

effect of standing in glass for 17 months, the 

correction for any one of the 14 results is only 

about 2 per cent of its value, a correction just 

about equal to the possible experin1ental error. 

DISCUSSION OF RESULTS FOR THE TOTAL 

CARBONATE AND BICARBONATE. 

Dittmar made determinations of the "alkalinity"-that is, the combined carbonate and 

. bicarbonate-in 130 samples of water collected 

on the Ohallenger. 1 It was his opinion that the 

results were unaffected by long preservation of 

the water in glass bot.tles. The mean of all his 

determinations gives a normality of 0.00249. 

The meanior the Gulf waters, as shown above, 

is 0.00244. Ruppin obtained on shipboard in 

with an excess of calcite, was agitated by a 

current of outdoor air for long periods at different temperatures, and the dissolved carbonates 

were determined by titration with 0.02 normal 

NaHS04, methyl orange being used as indicator. The results obtained are shown in 

Tables 11 and 12. 

TABLE H.-Determinations of total C03+HC03 when calcite 

is added to sea water at 1 ° C. and air passed daily. 

Time. 

.Start ...................... . 10 days ................... . 12 days ................... . 14 days ................... . 33 days .................... · 40 days ................... . 

Carbonates 

per liter 

normality. 

0.00247 

. 00246 

. 00241 

.002~ 

. 00230 

. 00236 

'rABLE 12.-Determinations of total C¥J 3+HC03 when calcite 

is added to sea water at roo·m temperature and air passed 

daily. 

Tem- Carbonates 

Time. pera- per liter ture 

(oC.). normality. 

Start ............. ,. ........ 0.00247 

10 days ............ 25 . 00225 

12 days ............ 25 . 00221 

14 days ............ 26 . 00215 

33 days ............ 28 . 00199 

35 days ............ 29 . 00208 

40 days ............ 28 . 00196 

the North Sea 0.00238. Dole's figures for the The results obtained show that under conwater at 'fortugas (p. 2) give a normality of. ditions otherwise similar there is a tendency 

0.00234. for the colder sea water to retain more carNow, as pointed out in the introduction, bonate in solution than the warmer sea water. 

there is a need for study of the relation between What was not expected, however, is the fact 

the solubility of calcium and magnesium com- that the colder water did not dissolve fresh 

pounds and temperature. In 1915 I investi- calcite but appears rather to have remained 

gated the solubility of magnesium and calcium almost unchanged during the 40 days' run. 

carbonates in pure water and determined the In other words, sea water appears to be so far 

relation between the solubility of calcite in saturated with respect to calcium carbonate 

water in contact with the atmosphere and the that in contact with the atmosphere at 1° C. 

temperature. (For reference see p. 1.) Fur- it neither has nor acquires an appreciable 

thor determinations seemed desirable for solvent action on calcite. J\.t higher ternsea water, and such determinations have peratures it undergoes a slow diminution in its 

now been made on a portion of the water content of carbonates on being agitated in 

collected at Fowey Rocks Light, outside contact with outdoor air. 

Biscayne Bay, Fla. The water, in contact To ·compare with the above determinations, 

I Dittmar, W., Challenger Uopt., Physics nnd chemistry, vol. 1, p. 124, 

1884. 

I had, fortunately, been able to make a few 

titrations at sea. At two points in the 
10 SHORT·ER CONT·RIBUT10NS TO GENERAL GEOLOGY, 1918. 

Caribbean Sea, about latitude 13° N., longi-

. tude 81° W.; the. normality of the carbonates 

was found to be 0.00236 and 0.00238 at 25 ° C. 

Water from the Pacific off Payta, Peru, at 

24° ·C., gave 0.00226. These figures are a 

little higher than those found in the laboratory 

after a few days' agitation and suggest a condition of saturation, under atmospheric conditions, although they throw no light on the 

variations with temperature.· 

TABLE 14.-Ruppin's determinations of C0.3+HC03 for 

water of the No~t~ Sea, depth 5 meters .. 

Let us now consider all the data available on 

surface sea water to see if the results show a 

definite relation between the normality of 

carbonate and bicarbonate and the temperature. 

Of Dittmar's 130 results the 14 for surface 

waters· are reproduced in Table 13, after 

recalculation to the terms used here. 

Date. 

Feb. 18, 1907 ................... . May 6, 1907 ................... . May 10, 1907 ......... ~ ........ . May 8, 1907 .................... . May 5, 1907 ................... . May 12, 1906 .................. . May 19, 1906 .................. . Nov. 14, 1906 ................... . Do ........................ . May 11, 1906 .................. . Nov. 14, 1906 .................. . Do ......................... . Nov. 1g, 1906 ................... . Aug. 17, 1906 .................. . Do ........................ . Aug. 15, 1906 ................. ~. 

Do ........................ . 

Tempera- CO HCO 

ture a+· 3 

Co C.). normali,ty. 

4. 5 

6. 0 

6.2 

6.4 

G. 7 

7. 5 

9. 1 

9. g 

9. 4 

9. 4 

9. 5 

11. 4 

12. 4 

15. 1 

15. g 

15. 9 

16. 2 

O.Oo2g6 

. oo2g6 

. oo2g2 

. 00240 

. 002g7 

. 00242 

. 00241 

. 002g8 

. 002g8 

. 00242 

. 002g8 

. 002g9 

. 00240 

. 002g2 

. oo2g6 

. 002g9 

. 002g4 

It is difficult to see much if any regularity 

with regard to temperature. in the results 

given in Table 13. There i3 a slight indication 

that the normality of 003 +HC03 decreases 

with rising temperatme, but the results are too 

few and too unreliable to show 'the relation 

with certainty. 

Mean .................•............ . 00238 

Sample 

No. 

g84 

1271 

1471 

2 

9 

1700 

1687 

"265 

g27 

1581 

157g 

201 

1127 

668 

Apparently, then, although the variation in 

the no~mality of'C03 +HC03 with temperature 

can be shown in the laboratory, it is not very 

evident in published determinations for surface water of th9 open ocean. 

TABLE 1g.-Dittmar's determinations of C03+HC03 for surface waters. 

Locality. 

Tempera- COa+HC03 ture 

Co C.). normality. 

Indian Ocean, lat. 65° 42'S., Ion§. 79° 491 E ............................... · ...... -1.1 0.00~55 

South Pacific Ocean, lat. g3o 56' ., long. 116° 81 W ............................. 11. 9 . 00234 

South Atlantic Ocean, lat. 41° g9' S., long. 54° 48' W ............................ 15.g . 002g5 

North AtlaRtic Ocean, lat. 27° 24' N., long. 16° 55' W ............................ 18.0 . 00286 

North Atlantic Ocean, lat. 24° 22' N ., long. 24° 111 W ............................ 19.4 . 00260 

North Atlantic Ocean, lat. goo 20' N., long. g6o 61 W ............................. 21. 9 . 00248 

North Atlantic Ocean, lat. 21° g3' N., long. g1o 15' W ............................ 22.8 . 00248 

South Atlantic Ocean, lat. 22° 15' S., long. g5o g7' W ............................ 22.8 . 00260 

Indian Oceap., lat. g6o 48'S., 19° 24' E ......................................... 22.8 . 00253 

South Atlantic Ocean, lat. 19° 551 S., long. 13° 56' W ............................ 24. 7 . 00250 

'South Atlantic Ocean, lat. 23° 27'S., long. 13° 51' W ............................ 25. 1 . 00246 

North Atlantic Ocean, lat. 1.0° 251 N., long. 20° go' W ............................. 25.5 . 00241 

South Pacific Ocean, lat. go 48'S., long. 152° 56' W .............................. 26. 1 . 00240 

Near Philippine Islands, lat. 9° 10' N., long. 124° 25' E .......................... 27.2 . 00234 

Mean ................................................................... .......... . 00249 

Further determinations were made in the 

North Sea by Ruppin on the Poseidon.1 Some 

of his results are shown in Table 14. 

Analyses of some of the warmer and nearly 

inclo~ed seas, on the other hand, show a decrease in the carbonate content. Natterer 2' 

found that in the Red Sea, for instance, the 

carbonates are low and the deposition of solid 

carbonates takes place. It is evident that 

chiefly in such portions o~ the ocean or in the 

In Ruppin's results, also, no relation between 

the carbonate content and the temperature 

can be discovered. 

1 Ruppin, E., Die Alkalinit1it des Meerwassers: Zeitschr. anorg. 

Chemie, vol. 66, p. 122, 1910. 2Natterer, K., Monatsh. Chemie, vol. 20, p. 1, 1899. 
CARBON DIOXIDE IN WATER OF THE GULF OF MEXICO. 11 

polar regions will there be fopnd marked manifestations of the temperature effect on the normality of COs +f.ICOs. 

In Dittmar's determinations for cold bottom 

waters, however, high values of the normality 

are found. But as the mean of his figures for the 

surface waters of Table 13, 0.00249, agrees with 

the mean of all his determinations, it follows 

thut the intermedi~te samples actually show a 

lower normality of carbonates than either surface or bottom samples. I· obtain from his 

data 0.00243 for 49 samples from intermediate depths. Moreover,· the mean for 25 samples at temperatures below 11° is e~~ctly the 

Table 15 cont~in~ a summary. of the conclusions so far suggested concerning the total 

C02 and the normality of the bases balancing 

C03 and HCOs with reference to a condition 

of equilibrium with the atmosphere. 

. The conclusions concerning ocean water do 

not involve the greatest depths or the c.o.ld 

polar regions. It will be seen that by po~tulating a slight deficit of C02 and bases in the 

intermediate ocean waters these waters will be 

ready to increase their C02 if they come in to contact with the bottom. As a matter of fact, 

however, they must be surrounded by extensive layers of water in which equi.librium preTAm,E 1.5.-Conclusions suggested from the investigation with reference to a condition of equilibrium with the atmosphere; 

Depth. 002. Bases. 

0 

Ocean water of tempern.te re- turface ................. Slight excess ................. Slight deficit .................. Slight excess. Intermediate ........... Slight deficit. · gionsdown to3,000fathoms. Bottom ................. Equilibrium or excess ......... Equilibrium or excess. 

Gulf of Mexioo water ....... {Surface ................. Slight excess ................. Equilibrium ......... · ......... Slight excess. Intermediate ........... 

same as the mean for 24 samples at temperatures above 11°. The value 0.00243 would 

therefore appear to be the most representative 

value of the normality for the whole ocean. 

But the variation with temperature, except for 

the bottom samples, does not appear in. Dittmar's results. Such a variation, however, is 

found in the Gulf waters. It may be that in 

the intermediate waters of the open ocean 

there is lacking a source of the bases or possibly of C02 • On the bottom there n;tay be a 

source of carbon dioxide in the decay of organic mntter and of the bnses in the inorganic 

materinl, which would explain high results for 

bottom samples. The slight excess in the 

COs +HCOs normn.lity for the surface waters, 

however, is more difficult to account for. If 

it is due to additional bases, where do they 

come from~ Possibly river water or organic 

life at the surfn.ce-such as algae-ac.t as competent sources of the hades. The atmosphere or 

organic life could furnish the carbon dioxide, 

but in view of the experiments whose results 

are given in Tables 11 and 12 sea water does 

not appear to be in a condition to receive carbon dioxide from the atmosphere except at 

the very coldest temperatures. This leaves 

river water and organic life as the chief probable agencies contributing carbon dioxide to 

the surface waters of the ocean. 

Equilibrium. 

vails,· as the surface and bottom .. concentrn.-

tions are excessive. It is interesting to recall 

in this connection that the waters of the southern and western Pacific seem to be defieien t in 

both carbon dioxide and bases balancing COs 

and HCOs. These very general conclusions 

are the. best that can be drawn from all the 

evidence. In any actual· series of samples, 

however, variations seem to occur which suggest that there rna y well be local variations 

due to organic activity that operates faster 

than the mixing of the water. Chemi-cal tests 

are commonly made on comparatively small 

samples of the water, and it may be that 

greater constancy would be obtained if larger 

samples could be employed. 

CALCULATION OF CARBONATE AND 

BICARBONATE. 

The amounts of carbonate and bicarbonate 

present may first be calculated on the assumption that all the C02 found is combined as 

C03 and HC03 balancing bases. Thus, for 

water 7 in Tables 2 and 10 let x=normality 

of C03 and y =normality of HC03 • Then 

22x + 44y = 0. 092 

and x + y = 0.00242 

whence y = 0.0018 and x = 0.0007. 

The results thus obtained for the 15 samples 

are shown in the last two columns of Table 10. 
12 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

These results ·average, as they stand; 0.0018 

for the bicarbonate normality and 0.0006 for 

the carbonate normality .. Dole's average results for Tortugas water, obtained exclusively 

by titration methods, are 0.0016 and 0.0008, 

respectively (from 0.069 and 0.017 gram C02 in 

the two forms; see p. 2). From Dittmar's 

figure of 0.092 gram per liter for the total C02 

in water of the North Atlantic at 22.8° C. 

(Table 3) and a normality of 0.00243 for 

HC03 +CO:u I obtain 0.0018 and 0.0006 for the 

normalities of HC03 and COs, respectively, 

which are identical with the figures for the 

Gulf surface water, given in Table 10. 

. Let us next consider the magnitude of the 

error introduced by neglecting free carbon ,dioxide in the above calculations. The combination of Dole;s mean values for COs and 

I-ICOs with my mean value for the total C02 

in surface Gulf water gives 0.006 gram· per 

liter free C02 • If this figure correctly represents the free C02 it would leave for sample 7, 

for example, 0.092-0.006 = 0.086 gram C02 for 

the HCOs and C03 • The calculation will then 

be as on pa;ge 11 : 

22x+44y =0.086 

and x+ y =0.00242 

whence y = 0.0015, the normality of HCOs, and 

x = 0.0009, the normality of COs balancing an 

equivalent amount of base. These results 

differ markedly from those first obtained, 

namely, 0.0018 and 0.0007 for the normalities 

of HCOs and COs respectively, and show 

clearly the order of the uncertainty involved 

in the concentrations under discussion. It 

should be noted, however, that the uncertainty 

is no longer in the amount of total C02 but 

only in the separate concentrations of the 

three forms in which the C02 is conventionally 

stated. 

Johnston1 states that the free carbon dioxide 

can be calculated if the total ion concentration 

of base, lB+], and the hydrogen-ion concentration, [H+], are known. The hydrogen-ion 

concentration can be determined by indicators 

or by the hydrogen electrode, but for several 

reasons it was not determill!ed in the waters 

under scrutiny. The determination of [B+] 

involves some theory and uncertainty, and 

1 Johnston John The determination of carbonic acid, combined and 

free, in solutlon, p~rticularly in natural waters:· Am. Chern. Soc. Jour., 

vol. 38, p.· 955, 1916. 

therefore a few illustrative calculations must 

suffice. Johnston gives the· following figures 

for the free carbon dioxide when [B+] equals 

0.001, which is comparable with the normality 

of HCOs found in sea water: 

[H+]. Free carbon 

dioxide. 

10-6 

Gram pe:r liter. 

0. 130 

10-7 .013 

lo-s . 0013 

10-9 . 00016 

For [B+) = 0.01 the corresponding values are 

ten times those given above. 

Suppose that in sample 7 [H+] = 10-7 and 

[B+]=0.002, then free C02 =0.026 gram per 

liter, leaving . 0.092-0.026 = 0.066 gram for 

I-I COs+ COs. The calculation will then be, as 

before, ' 

22x + 44y = 0.066 

and x+ y=0.00242 

whence y=0.0006, the normality of I-IC03 , and 

x = 0.0018, the normality of COs. These results may probably be regarded as extreme, 

as [I-I+] for sea water may be as low as or lower 

than lo-s. If [H+] = 10-s the free C02 will be 

0.0028 gram, making HC03 = 0.0016 and 

COs= 0.0008. If [B+] il?l less than 0.002 the 

quantity of free C02 will be less. 

In a paper on the alkalinity of sea water 

Sorensen and Palitzsch 2 record determinations on a series of 24 samples of surface water 

from the Atlantic in which [H+] ranges from 

1 o-6.84 to 1 o-7 .sl. 

Recent determinations by Gaarder s yield 

values for [OH-] running from 0.5 X I0-7 

to 25 x 10-7 ; or, for 20°, [H+] = 1.3 X I0-7 

to 2.6 x 10-9

, which is somewhat less acid 

than that obtained by Sorensen and Palitzsch. 

According to the determinations of McClendon 4 the water at Tortug~s gives [H+] = 

1 o-s.l to 1 o-s.z. 

2 Sorensen, S. P. L., and Palitzsch, S., Sur le mcsurage de la concentration en ions hydrogime de l'eau de mer: Lab. Carlsberg Com pt. rend. 

trav., vol. 9, p. 8, 1910. · 

a Gaarder, Torblorn, Hydroxyl number of pure water and sea water: 

Tidskrift Kemi Farm. Terapi, vol. 13, pp. 93-105, 135-137, 152-156, 169-

172,181-187,198-201,1916. 

4 McClendon, J. F., Experiments with Tortugas sea water: Carnegie 

Inst. Washington Year Book 15, p. 207, 1916. See also Mayer, A. G., 

Observations upon the alkalinity of the surface water of tho tropical 

Pacific: Nat. Acad. Sci. Proc., vol. 3, p. ~48, 1917. 
CARBON DIOXIDE .IN WATER OF THE G.ULF OF MEXICO. 13 

Some further light is thrown on this problem These relations correspond to the known 

by the comparison brought out in Table 7: effect of temperature on the solubility of 

It was shown that the Gulf waters appear to carbon dioxide in water, on the solubility of 

be very near equilibriu1n with the atmosphere. calcium carbonate in water, and on the 

That being true, we may evaluate the free C02 hydrolysis of carbonates. An increase in 

by the second term of Fox's equation (p. 5). total 002 therefore corresponds to an increase 

as that term is intended to represent the C02 in HC08 but not in COs. 

present in physical solution, the average For the sake of completeness, Buchanan's 

partial presstrre of C02 for all the waters determinations, made during the cruise of the 

being taken as, say, 0.00032 atmosphere .. Ohal·lffiger, of the amount of carbon dioxide 

The free C02 thus calculated ranges fro:q1 elim.lnated from sea water by boiling are 

0.0005 to 0.0006 gram per liter. Although 'presented for comparison. There has long 

I-Ienry's law is now known to be inapplicable been some uncertainty as to the exact sigwith exactness to very dilute solutions of C02, nificance of the results/ but they must be of 

the figures just given are far smaller than 

those calculated above for [l-J+] = 10-7 and 

10-s. Further investigation is needed to clear 

up this discrepancy. 

0.06 0 

In view of the uncertain factors here noted ~ 

the figw·es in. 'rable 10 1nay be allowed to stand ] .05 

as preliminary estimates of the proportions i 

of carbonate and bicarbonate. In future 

determinations it will be desirable to evaluate j 

[I-I+] along with the other determinations and ~ 

0 

8. 

correct for the free C02 as far as possible. ~ .040 

It would obviously be incorrect to calculate c 

the COs and I-ICOs separately from the total 

C02 without correcting for the free C02 wheil 

.080 

~ 

~ ~ 

' 

0 0 c. 

"" "" ~ 

~ 

X 

~ X 

)( ~ 

~ 

0 0 

10 20 

Temperature 

the total C02 is exceptionally high and tl1e . 

total I-ICOs +COs low, but such high total C02 

seems to be the exception in warm ocean 

water. If we assume a mean value of 0.003 

I C 11 h FIGURE 1.-0urve showing variation of loosely combined carbon 

gram per iter of free 0 2 in a t e samples dioxide in surface sea water with temperature. The crosses represent 

of Gulf water analyzed, the mean values for tho 12 means given in Table 16. 

the HC08 and COs ;normalities for the Gulf 1 . va ue as comparative determinations, having 

water would be 0.0017 and .0.0007 respectively. all been made by the same method. I have 

As a matter of fact, however, the free C02. studied Buchanan's results for surface waters 

varies from one sample to another, like the with reference to the equilibrium that should 

other concentrations, and· a complete state- exist between the waters and the atmosphere 

ment for each sample would require the in respect to carbon dioxide, and I find the 

determination of at least three unknown quan- clearest indication of a relation between the 

tities-better four, in order to check the results. temperatw·e of the water and its content of 

An examination of the results for the car- loosely combined carbon dioxide. Apparently, 

bonate and bicar~onate . give~ in Table 10 also, there is a difference between the Atlantic 

s~ows that there Is a .shght Increas~ of the and the Pacific waters, but if the results for 

biCarbonate concentratiOn and a s~Ight. d~-· the surface waters are arranged solely accordcrease ~f ~he carb?nate concentratiOn Indi- ing to temperature the general relation is that 

c~ted With Inc~ease In depth, or, one rna~ s~y, th~ amount of loosely combined carbon dioxide 

~Ith decrease In temperature. The va.n~tw.n is grea~er in the colder waters. (See Table 16 

IS not gr~at but ~tppears to be real; If It IS and' fig. 1.) 

real, an Increase 1n temperature corresponds 

to a decrease in total C02

, in the total C03 + 1 Challenger Rept., Physics and chemistry, vol. 1, p. 100, 1884. PreI-ICOs, and in HCOs, and an increase I·n COs. sumably Buchanan's results give the C02 of bicarbonate together with 

free C02 if present. 

28288°-19-2 
14 SHORT·ER CONTRIBUTIONS TO GENERAL GEOLOGY, .1918. 

TABLE 16.-Buchanan's determinations of loosely combined carbon dioxide in surface ocean water, arranged according to the 

temperature of the water. · . . t 

Sample Tempera- Loose 

Locality. carbon No. ture. dioxide. 

oc. 

Gram per 

liter. 

389 South Indian Ocean, lat. 64° 521 S., long. 83° 12' E .. _____________ ................. -1.7 0.049 

386 South Indian Ocean, lat. 66° 291 S., long. 78° 18' E ................................ - . 7 . 056 

396 South Indian Ocean, lat. 64° 1' S., long. 87° 411 E ............................ _ ... _ .4 . 049 

382 South Indian Ocean, lat. 64° 21 S., long. 79° 55' E ....................... _. __ ...... .7 . 066 

387 South Indian Ocean, lat. 65° 10' S., long. 78° 421 E ...................... _ .. : .. _ ... .7 . 052 

380 South Indian Ocean, lat. 62° 221 S., long. 80° 41 E .................... _ ...... ____ ._ 1.1 . 064 

l\1ean ... __ . _ . _ .... ___ .... ______ . ___ . _______ . _ . _ ... _ .. _________________ · ____ .1 . 056 

415 South Indian Ocean, lat. 53°131 S., long.109° 231 E ................. : .......... _ .. 4.3 . 052 

354 South Indian Ocean, lat. 46° 16' S., long. 48° 271 E .............. :· ........... _ ..... 5.0 . 054 

364 South Indian Ocean, lat. 46° 53'S., long. 51° 521 E._ ...................... _ ..... _. 5.0 . 047 

360 South Indian Ocean, lat. 46° 81 S., long. 49° 40' E .............................. _ .. 5.8 .051 

417 South Indian Ocean, lat. 50° 54'S., long. 118° 3' E ................................ 7.2 .054 

Mean .......... : ................ ------------·-·------------------·-----·-- 5.5 . 052 

1272 South Pacific Ocean, lat. 38° 43'S., long. 112° 31' W ................................ 11.8 I . 037 

1287 South Pacific Ocean, lat. 39°191 S., long. 101°191 W---~--- .................... _ ... 12.5 .042 

1378 S:outh Pacific Ocean, lat. 42° 19' S., long. 84° 47' W ................................ 12. 7 . 047 

1390 South Pacific Ocean, lat. 45° 311 S., long. 78° 91 W ............................... _. 12.7 .049 

1314 South Pacific Ocean, lat. 38° 19' S., long. 84° 251 W ............................... _ 13.6 . 037 

1375 South Pacific Ocean, lat. 39~ 41' S., long. 86° 331 W __ . _. _ ......................... _ 13.9 . 046 

Mean .... _ ......... _ ...... ________ . ____________ .. ____________ . _ . _ ... ______ 12.9 .043 

1462 South Atlant'ic Ocean, lat. 42° 321 S., long. 56° 291 W .............................. 14.2 . 039 

1374 South Pacific Ocean, lat. 38° 59'S., long. 83° 53' W ................................ 14.2 .051 

\ 1301 South Pacific Ocean, lat. 37° 551 S., long. 93° 561 W ................................ 14.7 . 035 

1366 South Pacific Ocean, lat. 36° 171 S., long. 83° 50' W ~ _ .. _ ................... _ ....... 15.5 .048 

1367 South Pacific Ocean, lat. 36° 581 S., long. 83° 40' W ............... _ ........ _ ...... _ 15.5 -047 

471 South Pacific Ocean, lat. 37° 2' S., long. 160° 481 E .. __ ._ .......................... 15.6 . 050 

Mean .... _____ ... ______ _. __ . ____________ ._. __ . __ . __ .. _. _________ . __________ 15.0 -045 

1342 South Pacific Ocean, lat. 33° 20'S., long. 74° 24' W ------- .. --- ... -- .............. -I 16.9 -036 

1352 South Pacific Ocean, lat. 32° 50'S., long. 77° 6' W .......... _ ... _. _. _ ... _ .......... 17.5 . 038 

497 South Pacific Ocean, lat. 31° 23'S., long. 177° 48' W---------- ... ------------------ ·1 17.8 . 059 

949 North Pacific Ocean, lat. 37° 35' N., long. 163° 461 W ............................... 17. 9 . 029 

Mean ..... --- .. ----.-------------~------------------:--------~-------.~--- -I 17.5 . 040 

504 South Pacific Ocean, lat. 28° 25'S., long. 177° 93' W ............. _ ... _. _ ._ .......... 19.4 . 041 

276 South Atlantic Ocean, lat. 27° 541 S., long. 31° 221 W _. ___ . _ ... _____ ......... _ .. _ .. 19.4 .043 

1508 South Atlantic Ocean, lat. 36° 55'S., long. 44° 50' W .. _____ .. ____ ..... _ ... _ .. _ .. _. 20.0 .034 

1699 North Atlantic Ocean, lat. 29° 50' N., long. 35° 55' W ....... _. _ ...... · ........ __ .... 20.5 .034 

836 North Pacific Ocean, lat. 28° 23' N., long. 137° 45' E ....... _. ___ .. _._ .. ___ ... _ .... __ 20.8 . 03.2 

267 South Atlantic Ocean, lat. 24° 43'S., long; 34° 171 W _. ___ ............ ___ . _. __ . ____ 21.0 . 042 

Mean. -.. - -. - -. - - - -.. - . - - - - -·_: . -·- --... ------- - -.. --------. -. ----........ --I 20.2 .038 

136 North Atlantic Ocean, lat. 37° 52/ N., long. 42° I' W ..................... _ ... _._ .. _I 21. 1 .053 

117 North Atlantic Ocean, lat. 34° 511 N., long. 63° 59' W ............................. _1 21.4 .045 

910 North Pacific Ocean, lat. 35° 551 N., long.l71° 541 E ................... _._ .... _ .... 21. 7 . 035 

826 West Pacific Ocean, lat. 24° 471 N., long. 138° 34' E .................... _._ ......... 21.8 . 021 

926 North Pacific Ocean, lat. 36° 59' N., long. 178° 561 W ............................... 21. 9 . 027 

512 South Pacific Ocean, lat. 23° 18' S., long. 173° 26' W ................... _ ........ _ .. 21. 9 .036 

Mean·-···------·-------------------------------·--------------------·-··· ,21. 6 .036 

75 North Atlantic Ocean, lat. 27° 491 N., long. 64° 591 W .......................... __ .. 22. 2 .048 

1687 North Atlantic Ocean, lat. 21° 33' N., long. 31° 151 W .................. _ ........... 22.8 . 037 

1684 North Atlantic Ocean, lat. 17° 491 N., long. 28° 281 W ... __ ............. _ .. __ ...... _ 22. 7 .038 

265 South Atlantic Ocean, lat. 22° 15' S., long. 35° 371 W .... __ ........... _ .. __ .. _ : . ... 22.8 . 059 

119 North Atlantic Ocean, lat. 32° 54' N., long. 63° 221 W ...... ___ .. _. _ ....... : ........ 23. 3 .042 

Mean •....••••••••••••..•••.•.. ~ ..••••••.............. ____ ... ______ .. _____ 22.8 . 045 
CARBON DIOXIDE IN WATER OF THE GULF OF MEXICO. 15 

TABLE 16.-Buchanan's determinations of loosely combined carbon dioxide in surface ocean water, arranged according to the 

temperature of the water-Continued. 

Sample Locality. Tempera- Loose 

carbon No. ture. dioxide. 

oc. 

Gram per 

liter. 

990 North Pacific Ocean, lat. 30° 51' N., long. 154° 23' W .............................. . 68 North Atlantic Ocean, lat. 21° 26' N., long. 65° 16' W ..... ______ ............. ____ .. 515 South Pacific Ocean, lat. 20°9'S., long. 176° 471 W ............................... . 1581 South Atlantic Ocean, lat. 19° 55'S., long. 13° 56' W ............................. . 572 West Pacific Ocean, lat. 11° 37'S., long. 142° 59' E ................................ . 1573 South Atlantic Ocean, lat. 23° 27'S., lcng. 13° 51' W .......... , ................... · 1590 South Atlantic Ocean, lat. 14° 59'S., long. 13° 42' W ............................. . 256 South Atlantic Ocean, lat. 14° 51'S., long 37° 1' W ................................ . 

23.9 0.019 

24.4 .046 

24.5 . 061 

24. 7 .038 

25.0 . 027 

25. 1 . 035 

25. 1 . 035 

25.3 . 033 

1\fean ............ ·.·· ........... -.- .... -.-- .. -- ···- ·- · · ······ · ··· ·· · · · · · · · · 24.7 . 037 

209 North Atlantic Ocean, lat. 7° 71 N., long. 16° 11' W ............................... . 817 West Pacific Ocean, lat. 21° 17' N., long. 140° 40' E .............................. . 214 North Atlantic Ocean, lat. 6° 15' N., long. 16° 5' W ............................... . 539 South Pacific Ocean, lat. 16° 32'S., long. 163° 12' E .............................. . 228 North Atlantic Ocean, lat. 1° 471 N., long. 24° 26' W .............................. . 216 North Atlantic Ocean, lat. 4° 34' N., long. 13° 52' W .............................. . 

25. 7 .043 

25.8 . 025 

25.9 ·. 038 

25.9 . 032 

26.0 . 043 

26. 1 .043 

1\fean .................................................................... . 25.9 . 037 

215 North Atlantic Ocean, lat. 5° 48' N., long. 14° 20' W .............................. . 581 West Pacific Ocean, lat. 7° 13' S., long. 134° 18' E ................................. . 557 South Pacific Ocean, lat. 13° 50' S., long. 151° 49' E ............................... . 661 West Pacific Ocean, lat. 12° 21' N., long. 122° 15' E ................................ . 1097 North Pacific Oce?tn, lat. 7° 26' N ., long. 149° 22' W ............................... . 682 North Pacific Ocean, lat. 4° 33' N., long. 127° 61 E ................................ . 

26. 2 . 046 

26.4 . 039 

26. 7 . 036 

26.7 . 037 

26. 8 .029 

26.9 .025 

Mean .................................................................... . 26.6 . 035 

602 West Pacific Ocean, lat. 1°42'S., long. 127° 7' E .................................. . 7GO North Pacific Ocean, lat. 4° 21' N., long. 145° 18' E.; ............................. . 1662 North Atlantic Ocean, lat. 7° 10' N ., long. 15° 10' W .............................. . 

27. 9 .042 

28.4 .030 

28.6 .034 

1\Iean .................................................................... . 28.3 . 035 

We are now in a position to make a statement of the constituents of the salts in Gulf 

water, say for the surface at a temperature of 

18° to 20°0., which shall include the tota.l 002 as 

carbonate and bicarbonate. Based on Steiger's 

analysis (Table 1), it is given in Table 17, 

which includes also a si1nilar statement, based 

on Dittmar's analysis, for ocean water, say the 

open Atlantic at n1oderate depth at 18° to 20°. 

Table 18 gives the results of a calculation of 

the chemical equivalence of the basic and acid 

radicles that constitute the salts in the water 

based on the percentages of the constituents 

shown in Table 17. 

TAm.E 17 .-Revised analyses of salts in the G1tlf of Mexico 

and ocean water. 

Gulf of 

Mexico. Ocean. 

Cl............................... 55.23 55.21 

Br. ............................... . 17 .19 

S04-............................. 7. 54 7. 68 

HC03 ••••• ..... ... .. .. .. .. .. .... • 31 . 31 

003 •••••••• ••• •• • • • • • • • • • • • • • • • • • • • 05 . 05 

N a.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30. 79 30. 54 

K............................... 1.10 1.11 

Ca................................ 1. 22 1. 20 

Mg ................................ 1 __ 3,...... • ..,...59,..... 1 ______ 3_. 7~1 

100.00 100.00 

TABLE lB.-Equivalence of basic and acid salt constituents 

whose percentages are given in Table 17. 

Basic radiReacting 

values. Acid racliReacting 

values. 

cles. cles. 

Gulf. Ocean. Gulf. Ocean. 

---

Na ......... 1. 339 1. 328 CL ........ 1. 558 1.557 

K ........... . 028 . 028 Br .......... . 002 . 002 

Ca .......... . 061 . 060 804-- ...... . 157 .160 

Mg ........ . 295 . 305 HC03 ••••• . 005 . 005 

C03 ••••••• . 002 . 002 ------ ------ Sum of ba- Sum of acid 

sic equiv- equivalents .... 1. 723 1. 721 alents ... 1. 724 1. 726 
16 SHORT'ER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

SUMMARY. 

The determinations of carbon dioxide in water of the 

Gulf of Mexico recorded in this paper show that the total 

carb_on dioxide increases with depth-that is, with decreasing temperature-and the amounts found are very near 

though slightly below those required for equilibrium with 

atmospheric carbon dioxide, as calculated by Fox's 

equation. Determinations of the total concentration of 

base held in balance with the carbonate and bicarbonate 

radicles were also made; this quantity apparently increases 

slightly with decreasing temperature. The data presented 

do not permit an exact evaluation of the ''free '' carbon 

dioxide in the water, but a consideration of the uncertain 

factors upon which computation of the free carbon dioxide 

rests indicates that the amount is probably so small in the 

Gulf water that no appreciable error is made by expressing 

the total carbon dioxide found as a mixture of carbonate 

and bicarbonate. At any rate, the constituents thus 

determined, taken in the form of sallis and dissolved in the 

appropriate amount of pure water, would reproduce the 

Gulf water under the conditions existing when the samples 

were collected. 

() 
GEOLOGY OF NORTHEASTERN MONTANA. 

By ARTHUR J. CoLLIER. 

INTRODUCTION. 

REGION EXAMINED. 

A large region in northeastern Montana .has 

never been thoroughly explored by geologists, 

owing to the fact that it is a part of the Great 

Plains and the belief that it is too monotonous 

and uninteresting to tempt anyorie to turn aside 

frmn the pronounced geologic features a little 

farther w~st, for which Montana is noted. 

This region includes parts of Sherida~, Val!ey, 

Phillips, and Blaine counties. Its mvestigat.ion was begun by Smith 1 in 1908, when .he 

made a O'eologic survey of the Fort Peck Indmn 

Reservation. Beekly 2 explored a strip of land 

along the :Montana-North Dakota line from 

Missouri River to the international boundary, 

and Bauer 3 examined the townships in which 

Plentywood and Scobey are situated. 

Their results are here included with those of 

the writer, who during the field seasons of 1915 

and 1916 was engaged in an investigation of 

tho liQ'Il.ite resources of the remainder of this 

regio;, which extends from a line :vithin 12 

n1ilos of the Montana-North Dakota boundary 

westward about 200 miles. In the western 

hu,lf of the region very little lignite was found, 

and the work was of the nature of a hasty 

reconnaissance extending from the international boundary to Missouri River. A few 

townships are covered by old land surveys, a~d 

the corners are located with difficulty, other 

townships are still unsurveyed, and in some 

the work ho.s not yet been completed; though 

the corners were found in the field, no plats 

wore available. The townships in the eastern 

1 Smith, C. D., The Fort Peck Indian Reservation lignite field, Mont.: 

U. S. Oeol. Survey Dull. 381, pp. 40-59, 1910. 

2 neokly, A. L., Tho Culbertson lignite field, Valley County, Mont.: 

· U. S. Oool. Survey Bull. 471, Pl'~· 319-358, 1912. 

s Bauer, c. A., Lignite iu tho vicinity or Plentywood and Scobey, 

ShoridauCouuty, Mont.: U.S. Oeol. Survey Bull. 541, pp.293-315, 1914. 

part of the region. have been surveyed by the 

General Land Office within the last six or seven 

years. In the examination of the lignite be~s 

ih this area the plane table and telescopiC 

alidade were in constant use, and the locations 

of the outcrops were tied to the section corners, 

which are usually marked by iron posts and are 

easily found. 

ACKNOWLEDGMENTS. 

W. T. Thorn, jr., and R. F. Baker 'vere 

assigned to the :field party in 1915, and IL R. 

Bennett accompanied the writer in 1916. Edwin T. Conant was employed as teamster and 

assistant during both seasons. Much of the 

information contained in this report is the result of the faithful work done by these men. 

W. C. Alden, who in 1916 began. an investigation of the glacial features of eastern Montana, 

visited the party in the field and has frequently 

been consulted in the office. l-Ie has mooe 

many valuable suggestions, used in the preparation of this paper. . 

Acknowledgment is also due to :Mr. Barnum 

Brown, of the American Museum of Natural 

History, for suggestions made in the course of 

the field season of 1916. 

As the work in many parts of the region 

was more or less of a reconnaissance nature 

the only available map·s were township plats 

made by the General.Land Office. The Bowdoin, Saco,. Hinsdale, arid Cherry Ridge topographic maps of the United States Geological 

Survey; the maps to be published by the International Boundary Commission; the topographic maps of the Fort Peck Indian Reservation made by the General Land Office in connection with the township surveys and published by the Geological Survey; and the m_aps 

published by the Missouri River Commission 

have all been used in preparing this report. 

17 
18 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

The base map (Pl. I) is compiled from the 

township plats, with additions from the few 

topographic maps available and the field notes 

made by the writer and his assistants. 

PREVIOUS PUBLICATIONS. 

1875. 

Dawson, G. M., Geology and resources of the 49th parallel, British-North American Boundary Commission. 

1886. 

McConnell, R. G., On the Cypress Hills, Wood Mountain, and adjacent country: Geol. Survey Canada Ann. 

Rept., vol. 1. 

Cope, E. D., The vertebrates of the Swift Current Creek 

region of the Cypress Hills: Idem, pp. 79-85. 

McConnell discovered the interesting Oligocene mammal remains in the Cypress Hills, a few miles north of the 

international boundary, and Cope's report is on the fossil 

remains of the region. 

1891. 

Cope, E. D., The species from the Oligocene or lower 

Miocene beds of the Cypress Hills: Canada Geol. Survey 

Contr. Paleontology. 

1896. 

Weed, W. H., and Pirsson, L. V., Geology of the Little 

Rocky Mountains: Jour. Geology, vol. 4, pp. 399-428. 

1906. 

Calhoun, F. H. H., The Montana lobe of the Keewatin 

ice sheet: U. S. Geol. Survey Prof. Paper 50. 

1907. 

Brown, Barnum, The Hell Creek beds of the Upper Cretaceous of Montana: Am. Mus. Nat. Hist. Bull. 23. In 

this paper Brown refers to an extension of the "Hell Creek 

beds" northward across Missouri River, and hence in this 

field. 

1909. 

Dowling, D. B., Coal :fields of Manitoba, Saskatchewan, 

Alberta, and eastern British Columbia: Canada Geol. Survey Pub. 1035. 

1910. 

Pepperberg, L. J., The Milk River coal field, Mont.: 

U. S. Geol. Survey Bull. 381, pp. 82-107. 

Smith, C. D., The Fort Peck Indian Reservation lignite 

::fields, Montana: U. S. Geol. Survey Bull. 381, pp. 40-59. 

1912. 

Beekly, A. L.; The Culbertson lignite field, Valley 

·County, Mont.: U.S. Geol. Survey Bull. 471, pp. 319-358. 

1914. 

Rose, Bruce, Willowbunch coal area, Saskatchewan: 

Canada Geol. Survey Summ. Rept. for 1913, pp. 153-164. 

Bauer, C. M., Lignite in the vicinity of Plentywood and 

Scobey, Sheridan County, Mont.: U.S. Geol. Survey Bull. 

541, pp. 293-315. 

1915. 

Rose, Bruce, The Wood :Mountain coal area, Saskatchewan: Canada Geol. Survey Summ. Rept. for 1914, pp. 

64-67. 

1916. 

Stebinger, Eugene, Possibilities of oil and ga.-, in northcentral Montana: U.S. Geol. Survey Bull. 641, pp. 4!J-Gl. 

Rose, Bruce, Wood Mountain-V\7illowbunch coal area, 

Saskatchewan: Canada Geol. Survey Mem. 89. 

1917. 

Collier, A. J., The Bowdoin dome, Montana, a possible 

reservoir of oil or gas: U. S. Geol. Survey Bull. 661, pp. 

193-209 (Bull. 661-E). 

Collier, A. J., and Thorn, W. T., jr., The Flaxville gravel 

and its relation to the other high-terrace gravels of the 

northern Great Plains: U. S. Geol. Survey Prof. Paper 

108, pp. 179-184 (Prof. Paper 108-J). 

SURFACE FEATURES. 

The region here described is a part of the 

Great Plains of North America. By this designation it is not intended to imply that the 

whole area consists of only one plain, for in 

fact there are at least three levels at which 

remnants of fairly 'vell marked surfaces approaching plains can be discovered and between 

which there are more or less irregular slopes 

and escarpments. It can be assumed that at 

some very rem.ote time the whole of the Great 

Plains constituted one plain, which was subsequently elevated and probably warped. The 

increased slope made it possible for the streams 

to sink their channels into the plain and as 

time went on to destroy most of its even surface by the headward cutting of the tributaries. 

Other periods of uplift and erosion have made 

possible the production of partial plains below 

the original one, until the region to-day is 

marked by a series of terraces or remnants of 

these plains. Adjacent to the southwest corner 

of the region described are the high peaks of. 

the Little Rocky Mountains, which owe their 

origin to a totally different cause, namely, an 

intrusion of igneous rocks with which the 

underlying strata not elsewhere exposed are 

brought to the surface. Except for the Little 

Rocky Mountains the relief between the lowest 

point and the highest in this region is about 

1,400 feet. 

The highest points are in a series of plateaus 

near the Canadian line which are capped and 

protected from erosion by gravel. The plateau 

in the western part of the region stands at 
U. S. GEOLOGICAL SURVEY 

Base from U. S. Geological Survey map of Montana 

~ 

QUATERNARY TERTIARY 

~ 

TERTIARY (?) 

~ 

Eocene (f) 

CRETACEOUS 

Upper Cretaceous 

.1lfontltna group 

DLDDDD 

Alluvium Flaxville gravel Fort Union Lance formation Bearpaw shale "Jtidith River 

formation fOrmation 

Scale~ 

;;.,"""...;;"====ii""".,..,;c==i..-...0°<=============~z~MUes 

GEOLOGIC MAP OF NORTHEASTERN MONTANA Geology compiled from the work of C. D. Smith , 

A. L Beekly, C. A. Bauer, and A. J. Collier 

By Arthur Surveyed in 1908-16 J. Collier 

1918 
GEOLOGY OF NORTHEASTERN MONT AN A. 19 

3,000 to 3,400 feet above the sea, as is indicated on the Cherry Ridge topographic map of 

the Geological Suryey; east of it, for about 30 

miles, no remnants of the high plateau are 

found, but in the neighborhood of Opheim there 

is another extensive plateau at an altitude of 

about 3,100 feet, east of which the elevation 

declines to about 2, 700 feet in a plateau south 

of the town of Redstone. 

The Larb IIills, 1 near Missouri River, also consist of an undulating plateau about 3,000 feet 

in altitude but differing from the plateau far-

. ther north in not having a thick gravel cover. 

Outside of the areas occupied by these plateaus there is a marked bench of rolling land 

from 200 to 500 feet below the higher level. 

This bench can be seen to good advantage 

from Big Muddy Creek, northeast of Redstone, 

to the North Dakota line, as shown in the maps 

of the Boundary Commission, and ranges in 

altitude from 2,300 to 2,500 feet. At the 

. international boundary the Big Muddy Valley 

has steep walls rising 260 feet to the comparatively level plain. West of Big Muddy Creek 

tllis bench continues with varying altitudes, 

and along the forks of Poplar River it consists 

of long slopes extending from the upper escarpnlent down within 200 feet of the river ·level. 

West of Opheim it consists of level-topped 

areas, of sloping grass-covered llills, and of 

badlands in which the shale is exposed. It 

ranges in altitude from 2,5.00 feet near Milk 

River to 3,000 feet at the international boundary near the crossing of Frenchman Creek. 

The valleys of Rock, Frenchman, Whitewater, 

Cottonwood, and other creeks cut across this 

bench and are especially deep near Milk River. 

A view of the gorge of Rock Creek is given 

in Plate II, A, and the valley of Cottonwood 

Creek is shown in Plate III, A.. South of Milk 

River the elevated areas are generally somewhat lower, and the streams cutting across 

them occupy broad valleys from 100 to 400 

feet in depth. 

1 Tho namo Larb Hills has boen applied to the uplands immediately 

south of Saco and has been publisl1od on tho Bowdoin, Saco, and Hinsdalo topographic maps of tho United States Geological Survey. That 

this is au error is affirmed by many of the old inhabitants of the region. 

Messrs. Henry Carpenter and L. W. Gibson, who resided near the 

Missouri for many years, assort that tho urune was first applied to a rclatlvoly small area cast of Timber Crook. It is applied to the whole group 

of highlands ncar Missouri River on tho map by Calhoun published in 

U. S. Gool. Survey Prof. Paper 50. 

The valleys of Missouri and Milk rivers, 

ranging in altitude from 1,900 to 2,300 feet 

and lying from 100 to 500 feet below the level 

of the bench just described, together with the 

valleys of the smaller streams, constitute the 

lowest land in this region. The valley of Milk 

River is bordered by pronounced bluffs. It is 

in places several miles in width and was probably formed by a much larger stream than 

that which now occupies it. Calhoun 2 is 

authority for the sttl,tement that tllis valley 

was once occupied by Mis&ouri River and that 

it was completely filled with ice during the 

glacial epoch so that the river was forced to 

cut for itself a new valley (the present course) 

50 miles to the south. 

The present valley of Mi~souri River near 

the mouth of the Musselshell is cut from 300 

to 500 feet in the bench described and is not 

more than 3 miles across from rim to rim. 

(See maps published by the Missouri River 

Commission.) The river flows eastward in 

this narrow valley for many miles to the 

mouth of Big Dry Creek, in whose former 

valley it flows back to its original channel at 

the mouth of Milk River. 

The effect produced by . the n1oving of the 

continental ice sheet across this region is interesting and varied. In some areas the evidence 

of glaciation is almost entirely lacking, but 

even in such areas, if the surface has not been 

covered by deposits made since the glacial 

epoch, boulders of granite brought from the 

far-away shores of Hudson Bay, or large 

bodies of boulder clay, in part from the same 

source, can be found here and there. In addition to this evidence there are several glacial 

moraines marked by small irregularly placed 

lake beds separated by rounded hills. There 

are two large areas of this kind near the Canadian boundary--one in the eastern part of the 

region and the other extending fron1 VVhitewater Creek to the west side of the reO'ion b 

mapped. 

A description of the surface would not be 

complete without some reference to the Little 

Rocky ~1ountains, adjacent to the southwestem part of the region. These mountn,ins, as has 

2Calhoun, F. R. R., The Montana lobe of the Keewatin icc sheet: 

U. S. Geol. Survey Prof. Paper 50, pp. 38-42, 1906. 
20 SITORTER CONTRIBUTIONS· TO GENERAL GEOLOGY, 1918. 

beAn shown by Weed and Pirsson/ are of a 

peculiar type in that they have a central core 

of very 'old rocks covered by a mass of porphyry 

(a laccolith) intruded at some time very much 

later than the formation of the sedimentary 

rocks and are flanked by the upturned edges 

of the deep-seated strata. They furnish the 

only clue that can be obtained in this region 

to the strata that lie far beneath the surface. 

The Black Hills of South Dakota and Wyoming 2 present a much better known example 

of this form of mountain uplift, and the Little 

Rocky Mountains can be described as a miniature reproduction of the Black Hills. On the 

Little Rocky :Mountains there is a comparative 

abundance of timber, not only yellow pine and 

cedar but in n1any places fir, tamarack, and 

lodgepole pine. 

SETTLEMENT OF THE REGION. 

From the days of Lewis and Clark (1804-

1806) to the completion of the Northern Pacific 

Railway (1883) :Missouri River was the great 

northern route of communication between the 

East and the W e~St. Steamboats plied regularly on its muddy waters, bringing in supplies 

of all kinds and taking out pelts that the great 

fur com.panies had collected from the Indians 

and trappers. At that time many forts were 

built on the banks of the river to guard against 

attacks by the Indians, and one of the most 

important of these was Fort Union, which 

stood in this area opposite the mouth of Yellowstone River. 

The building of the first railway ended the 

river traffic, and as the region adjacent to the 

in tern a tional boundary was out of the ordinary 

line of travel, it was little visited until the 

completion of the Great Northern Railway 

about 1889. Up to that ti1ne the only inhabitants were Indians, trappers, traders, and 

woodcutters for the river steamers. Mter the 

building of the Great Northern Railway the 

country was practically given over to the 

raising of cattle and sheep. The railway staat many of ·these places, the principal crop 

being blue-joint hay. The :Milk River irrigation project of the Reclamation Service, begun 

many years later, has improved large areas of 

low-lying land. About seven years ago a tide 

of new life in the guise of "dry land" honlesteaders set in and is still swelling, though the 

more desirable land has been occupied. To 

meet this sweep of immigra~ion, townships 

have been surveyed, branch railroads built or 

projected, and new towns established. The 

best land~ from the farmer's point of view, is 

that on the flat surfaces of the higher plateaus, . 

where the soil is easily worked and produces 

good crops of grain and flax. The bench lai1ds 

are usually more rolling in character and are 

generally strewn with glacial boulders which 

must be gathered up before plowing. The soil 

on the benches in the eastern part of the region 

is derived largely from sandy forn1ations and 

is easily cultivated and fully equal to that of 

the plateaus. (See Pl. II, B.) Large areas 

in the western part are underlain by shale, · 

which forms a gumbo soil difficult to cultivate 

and on which the surface forms are more varied, but there are at many places large areas 

in which the invasion of ice during the glacial 

epoch has left a sandy soil that is easily tilled. 

The new homestead law, passed in 1917, which 

enables the settler to acquire 640 acres of land 

for grazing, will certainly encourage further 

settlement and will force the abandon1nent of 

the methods of the old stock-raising days. 

The principal towns in this region are Culbertson, Poplar, Wolf Point, Glasgow, Vandalia, Hinsdale, Saco, and :Malta, on the main 

line of the Great Northern Railway; Plentywood ano Scobey, on a branch of the Great 

Northern; Outlook and Whitetail, on the St. 

Paul, Minneapolis & Sault Ste. }.1arie Railway; 

·and Glentana and Ophein1, on proposed railroads not yet built. 

STRATIGRAPHY. 

tions became distributing points and have GENERAL SECTION. 

been t~e pri~cipal settlements for many ~ears.· The sedimentary rocks range from the preSmall 1rngatwn plants have been established Cambrian core of the Little Rocky Mountains 

I Weed, w. H., and Pirsson, L. v., Geology of the Littl,e Rocky to the Recent alluvium of the existing streams. 

Mountains: Jour. Geology, vol. 4, PP· 399-428, 1896. The source of the information regarding the 2 Darton, N.H., U.S. Geol. Survey Geol.Atlas,Sundance folio (No. 

127), 19os. rock from the pre-Cambrian to the Carbonifer-
cr. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 120 PLATE II 

A . GORGE OF ROCK CREEK, VALLEY COUNTY, MONT. 

B . GRAIN FIELD NEAR SCOBEY, MONT. 

C. CAMP I THE FOOTHILLS OF THE LITTLE ROCKY MOUNTAINS, PHILLIPS COUNTY, MONT. 
U. S. GEOLOGICAT, SURVEY PROFESSIONAL PAPER 120 PLATE III 

A. VIEW UP THE VALLEY OF COTTONWOOD CREEK, PHILLIPS COUNTY, MONT. 

B. BADLANDS OF DEARPAW SHALE NEAR LISMAS, MONT. 
GEOLOGY OF NORTHEASTERN MONTANA. 21 

ous is an article by Weed and Pirsson,t from 

which the followmg remarks on the rocks below 

the Carboniferous arc adapted. The .section 

from the Carboniferous to the Claggett shale of 

the Cretaceous system was examined during 

owing to undetected variations in the clip. 

The areal distribution of the formations is 

shown in figure 2. 

QUATERNARY 

~ 

OR TERTIARY 

.Ple'l.stor;ene or Zate Pliocene 

Terrace 

gravels 

The descriptions of the formations above the 

Claggett shale are the results of work done by 

R 25 E. R 26 E.. 

0 SMiles ~-----L------L------L----~~----~ 

2 3 4 

SEDIMENTARY ROCKS 

CRETACEOUS 

Montana group Colorado roup 

Lower Cretaceous 

,.---A----. 

Jud1th~1ver 

~mrn~·~~,~ Claggett Eag)el?l Coloradogroup Mowry Kootenaic?J 

fo.rmabon slia1e sana stone above Mowryst)ale shale formation 

SEDIMENTARY ROCKS' (ss,sandsto11t1member) IGNEOUS ROCKS 

CAMBRIAN PRE-CAMBRIAN 

Limestone 

~~ Limestone,lime- Crystalline 

stoneconglomerate, schists 

shale,and quartzite 

FIGURE 2.-Sketch map of tho geology ofT. 25 N., Rs. 25 and 2G E. principal meridian, Mont. 

the field season of 1916. Only one measure- the writer and his assistants in 1915 and 1916, 

ment of the section exposed was made, and it and the areal distribution of the~e formations is 

n1ay be found to be 1nore or less inaccurate shown in Plate I. The geologic section is as 

'Wood, W. H., and Pirsson, L. V., op. cit., pp. 399-428. given on page 22. 
22 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

Section of formations in northeastern Montana. 

System. Seri.es. I Group and forma- Thickness Character. tion. (feet). 

Sandy soil derived from Flaxville gravel, Fort Union, Lance, 

and Judith River formations. Gumbo soil derived from 

Recent. the Bearpaw and Claggett shales. 

Quater- " Alluvium deposited in the flood plains of streams. 

nary. ------Unconformity 

Scattered boulders, t~ll, and moraines. 

Pleistocene. Gravel deposited in Milk River valley by preglacial ~,.::issouri 

River. 

Unconformity 

Quater- Pleistocene or Gravel and silt north of Malta. Gravel O!l benches around 

nary or late Plio- Little Rocky Mountains. Tertiary. cene. Unconformity 

Early Pli- ocene or Flaxville gravel. 0-100 Gravel, sand, and clay, in some places cemented 'vith calcite. 

Miocene. 

Tertiary. Unconformity 

Eocene. Fort Union for- 0-1,400 Yellowish sandstone and shale carrying beds of lignite. mation. 

180-200 Somber-colored shale and sandstone; lignite beds. 

Tertiary)?). Eocene(?). Lance formation. 

80-200 Yellowish sandstone and shale. .......... ................ 

Bearpaw shale. 800-1,000 Dark-gray shale; marine fossils; gumbo soil. 

0.. 

::l Judith River Light-colored shale and sandstone; marine and fresh-water 0 400-425 bO formation. fossils; a somewhat sanely soil. <:il 

~ 

c6 Claggett shale. 750 Dark-gray shale, marine fossils, gumbo soil. +" 

Upper § Eagle (?) Light-colored sandstone present in Little Rocky Mountains 

Creta- ~ sandstone. 100 but probably absent in Bowdoin dome and points west. 

Creta- ceo us. ceous. 0.. 875 Bluish-gray to black shale. 

::l 

0 Light-colored sandstone capped by thin layer of fossililerous ~ 60± limestone. 0 

'0 

<:il 325 Dark-blue shale. 0 '""' 

'0 

0 Mowry shale. 100 Platy siliceous shale; weathers into porcelain-like debris. 

LowerCre- Kootenai ( ?) for- 825 Variegated shale interbedded with yellow and brown sandtaceous. mation. stone. 

Upper 200 .. Massive cross-bedded sandstone. 

Jurassic. Ellis formation. Jurassic. 200-300 Thin-bedded limestone and shale. 

U nconfprmity 

Carboni£- Mississip- Madison lime- Massive fossiliferous limestone. 

erous. pian. stone. Thin-bedded limestone.a 

Devonian 

(?) and Dark-gray and black fetid limestone.a Silurian(?). 

Thin-bedded limestone.a 

Cambrian. Limestone conglomerate. 

Green shale. 

Quartzite. 

Pre-Cam- Black crystalline amphibole schist.a brian. 

a Adapted from Weed, W. H., and Pirsson, L. V., Geology of the Little Rocky Mountains: Jour. Geology, vol. 4, pp. 399-428, 1896. 
GEOLOGY OF NORTHEASTERN MONTANA. 23 

PRE-CAMBRIAN ROCKS. 

The core of the Little Rocky Mountains is 

composed of crystalline schist (fig. 3). The 

type most usually seen is a fine-grained, dense, 

compact black crystalline amphibole schist or 

n.mphibolite, which splits into fragments with 

bright surfaces. These rocks are reported by 

Weed and Pirsson as being clearly altered 

sandstones. They are certainly older than the 

Cambrian. 

PORPHYRY LACCOLITH. 

Overlying the pre-Cambrian core of the 

Little Rocky Mountains is a great lenslike mass 

or laccolith of porphyry (see fig. 3), which was 

intruded at a much later date and which 

arched the overlying rocks in·~o a dome. The 

w. 

Fossils collected by Weed and Pirsson from 

the limestone mentioned in the section were 

examined by Walcott, who identified Ptychoparia oweni Hall and Obolella nana l\1:eek and 

Hayden. Both are :Middle Cambrian forms. 

SILURIAN AND DEVONIAN SYSTEMS (1). 

Above the Cambrian rocks (figs. 2 and 3) 

are slate-colored and black fetid limestones 

possessing the general characteristics of the 

Silurian and Devonian rocks as developed in 

the Rocky Mountain region to the west. No 

fossils were found in these rocks, and their 

tentative reference to the Silurian and Devonian systems by Weed and Pirsson is based on 

their lithologic character and position between 

the Cambrian and Carboniferous rocks. 

Anto.ine Butte c. Granite Butte 

FIGURE 3.-Soction of tho laccolith of tho Littlo Rocky Mountains, Mont. (After Weed and Pirsson.) a, Crystalline schists; b, granite porphyry; c, Cambrian; d, Silurian ( ?) and Devonian (?); e, Carboniferous;/, Mesozoic. 

exact thickness of the porphyry has not been 

measured, but it is known to be 300 or 400 

feet on the principal summits, where it rests 

upon black mica schist into which the streams 

have cut their gorges. The outlying buttes, 

like those shown in figure 3, probably represent 

lomtl thickenings or possibly separate intrusions 

of porphyry from which, in many places. the 

overlying rocks have not bee1~ eroded. 

CAMBRIAN SYSTEM. 

Camb!'ian rocks, of which Weed and Pirsson 

give the following section, lie upo11 the laccolith just described. 

Section of Cambrian 1·ocks in Little Rocky Mountains, 

:Mont. 

Thin-bedded fissile limestone, pure limestone with 

shell remains alternating with impme sandy and 

more or less conglomeratic beds; general color 

Feet. 

CARBONIFEROUS SYSTEM. 

MADISON LIMESTONE. 

The Carboniferous rocks (fig. 2) consist of 

several hundred feet of somewhat thinly 

bedded limestone at the base, capped by 

several hundred feet of massive, thick-bedded 

limestone which appears to be characteristic. 

of the Mississippian Madison limestone throughout the Rocky Mountain region. From this 

formation Weed and Pirsson report five species 

of fossils collected by E. S. Dana and pronounced lower Carboniferous by Whitfield.1 

Several collections of fossils, made principally by H. R. Bennett, have been examined 

by G. H. Girty, who has identified at least 

22 species and who declares that the formation 

is identical with the Madison limestone of 

other parts of Montana. I-Iis report follows: 

gray .......................................... . 

Limestone conglomerates and gray shale, greenish 

sandy layers alternating with pure argillaceous 

beds. There are so,me thin beds of limestone 

25 Sec. 33, 'f. 25 N ., R. 24 E. (lot 19): 

from which a few fossils were taken ........... . 

Green shale canying limestones and conglomerates. 

Green or copperas-colored shale .................... . 

Interval in which the beds are not exposed ......... . 

QuartJ~ite changing to conglomerate near the base, 

generally flesh-colored, mostly brecciated and 

rusty ......................... ~ ................. . 

40 

50 

30 

300 

75 

520 

Zaphrentis sp. 

Syringipora surcularia. 

Rhipidomella aff. R. burlingtonensis. 

Schuchertella chemungensis? 

Productus ovatus. 

Productus aff. P. viminalis. 

Productus gallatinensis? 

Productus (Strophalosia?) sp. 

Spirifer aff. S. incertus. 

1 Ludlow, William, Reconnaissance from Carol, M:ont., to Yellow .. 

stone National Park, p. 129, Washington, 1876. 
24 SHOR.TER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

Sec. 33, T. 25 N., R. 24 E.-Continued. 

Brachythyris suborbicularis? 

Martinia? sp. 

Syringothyris carteri. 

Athyris lamellosa. 

Euomphalus sp. 

Sec. 36, T. 25 N., R. 15 E. (lot 21): 

Zaphrentoid corals. 

Euomphalus sp. 

Same location as above but lower in section (lot 22): 

Triplophyllum sp. 

Schuchertella chemungensis. 

Chonetes ornatus. 

Spirifer centronatus. 

Reticularia cooperensis. 

Sec. 27, T. 25 N., R. 26 E. (lot 25): 

Leptaena analoga. 

Schuchertella chemungensis. 

Chonetes loganensis. 

Chonetes ornatus. 

Chonetes logani. 

Pustula n. sp. 

Productus ovatus. 

Productus arcuatus? 

Productus sp. 

Camarotoechia metallica; 

Camarotoechia sp. 

Dielasma aff. D. burlingtonense. 

Spirifer centronatus.r 

Syringothyris carteri. 

:Martinia rostrata. 

Spiriferina solidirostris. 

Reticularia cooperensis. 

Composita humilis. 

Cliothyridina cf. C. crassicardinalis. 

Platyceras sp. 

Same location as above but higher in the section (lot 26): 

Triplophyllum sp. 

Schuchertella chemungensis. 

Chonetes logani. 

Chonetes ornatus. 

Spirifer centronatus. 

Spiriferina solidirostris. 

Sec. 22, T. 25 N., R. 25 E. (lot 36): 

Triplophyllum sp. 

Fenestella, several sp. 

Pinnatopora sp. 

Batostomella sp. 

Rhombopora sp. 

Cystodictya sp. 

Schuchertella chemungensis? 

Schizophoria? sp. 

Chonetes ornatus. 

Chonetes logani. 

Chonetes loganensis. 

Productus arcuatus? 

Pustula n. sp. 

Camarotoechia atf. C. herrickana. 

Camarotoechia metallica. 

Spirifer centronatus. 

Camarotoechia mysticensis. 

Camarotoechia sp. 

Spiriferina solidirostris. 

Sec. 22, T. 25 N., R. 25 E.-Continued. 

Reticularia cooperensis. 

Martinia rostrata. 

Composita sp. 

Cliothyridina incr3ssata? 

Eumetria aff. E. vera. 

Entolium shumardianum. 

Platyceras sp. 

Griffithides? sp. 

It is probable that all six collections are of lower Mississippian age and belong to the Madison limestone, though 

they show several different faunal facies. Lots 22, 25, 26, 

and 36 are typical Madison faunas. Lot 21 shows too little 

for definite identification of the horizon. Lot 19 suggests 

a typical Burlington more than a typical Madison fauna, 

yet the Madison is in part of Burlington age, and collections 

from it sometimes show a markedly Burlington facies, 

like this one. 

The Madison limestone is the most striking 

formation surrounding the Little Rocky Mountains. It is the encircling girdle of the mountains, in which the picturesque canyons are 

cut. Seen from a distance it appears like a 

great horizontal bed, but on closer examination 

it is found to be turned up at high angles and 

its edge cut by deep canyons. The three 

small outlying domes sho·wn in figure 2 are 

1nade up wholly of this limestone. 

JURASSIC SYSTEM. 

ELLIS FOHl\fATION. 

Overlying the · ~rfadison limestone in the 

Little Rocky Mountains is a formation made up 

of shale and shaly and sandy limestone (fig. 

.2), which was described by Weed and Pirsson. 

A fauna from it, ·determined by T. W. Stanton 

as Jurassic, consisted of the following forms: 

Ammonite fragments of undetermined species. 

Belemnites densus Meek and Hayden. 

Pleuromya subcompressa Meek. 

Astarte meeki Stanton. 

Modiola subimbricata Meek. 

Gryphaea calceola var. nebrascensis Meek and 

Hayden. 

Larger collections from this formation were 

made by H. R. Bennett during the field season 

of 1916 and were identified by J. B. Reeside, jr., 

as follows: 

9832. Sec. 27, T. 25 N., R. 26 E. From shale above thinbedded shale and limestone which overlies the Madison 

limestone: 

Ostrea strigilecula White. 

Belemnites densus Meek and Hayden. 

Pleuromya sp.? 

Indeterminable casts of pelecypods. 
GEOLOGY OF NOR.THEASTERN MONT AN A. 

9832. Sec. 27, 1'. 25 N., R. 26 E.-Continued. 

Small ammonite distinct from described American 

forms but evidently a cardioceratjd. 

9833. Same locality as 9832 but lower in the section: 

Gryphaea calceola var. nebrascensis Meek and 

Hayden. 

Ostrea strigilecula White. 

Pleuromya subcompressa Meek. 

Astarte? sp. 

Hhynchonella sp. undescribed. 

Belemnites densus Meek and Hayden. 

Serpula sp. undet. 

Fragment of an undescribed ammonite, suggesting 

Perisphinctes. 

9834. Sec. 7, '1'. 25 N., H. 26 E. From thin-bedded limestone above the Madison limestone: 

Fragments of an ammonite suggesting Perisphinctes. 

Gryphaea calceola var. nebrascensis Meek and 

Hayden. 

Pleuromya subcompressa Meek. 

Pholadomya kingi Meek. 

Lima Cinabarensis Stanton. 

Cucullaea? sp. cf. C. haguei :Meek. 

Camptonectes extenuatus Meek and Hayden. 

Thracia? sp. like 1'. arcuata Meek but very much 

larger. 

H.hynchonella sp. undescribed. 

Belemnites densus Meek and Hayden. 

Astarte meeki Stanton. 

Cyprina? sp. 

9835. Sec. 7, 1'. 25 N., H. 26 E. From shale above thinbedded limestone which overlies the Madison limestone: 

Dosinia? sp. undct. 

Eumicrotis curta Hall. 

Ostrea strigllecl.1la White. 

Belemnites densus Meek and Hayden. 

Weathered casts of undetermined pelecypods. 

Smn.ll ammonite distinct from described forms but 

evidently a cardioceratid. 

Those fossils are Upper Jurassic. Jviost of 

the species arc known in the Sundance and 

Ellis formations, but several ammonites and 

a Rhynchonella are unlike any known Sundance 

forms. 

The detail of part of the Ellis formation 

which has been identified paleontologically 

is as follows: 

Section of Ellisfonnation. Feet. 

Shale with interbedded sandstone and limestone .. 100± 

Limestone, thin be.ddecl, shaly, and calcareous 

shale .......................................... 200 

300± 

Above the shaly portion there is a . more or 

less massive sandstone, which is tentatively 

considered as also belonging to the Ellis, 

though no fossils were found in it. It presents the following character in sec. 7, T. 25 N., 

R.26E.: 

Section of the sandstone in the upper part of the Ellis 

fonnation. 

Sandstone, massive, white, cross-bedded ......... . 

Shale, variegated ................................ . 

Sandstone, yellowish, and thinner bedded ........ . 

Feet. 

50 

50 

100 

200' 

The formation is almost identical with the 

Sundance formation of the Black I-Iills and the 

Ellis of other parts of Montana. As the 

:Madison limestone is ·of Mississippian age, 

there is necessarily an unconformity between 

it and the Ellis (Upper Jurassic), but the 

actual contact of the two formations has not 

been recognized. A photograph (Pl. II, 0) 

taken in the flanks of the Little Rocky Mountains in sec. 23, T. 25 N., R. 25 E., shows the 

camp situated on the outcrop of the Ellis 

formation in the foreground and the outcrops 

of the older formations in the background. 

CRETACEOUS SYSTEM. 

KOOTENAI ( ~) FORMATION. 

The sandstone just described is overlain in 

the Little Rocky Mountain section by variegated shale interbedded with yellow and brown 

sandstones, which are believed to represent the 

I{ootenai formation (Lower Cretaceous) of 

other parts of Montana, though they may ·possibly include the Morrison. The shale is in 

places blue, green, red, and gray. The approximate thickness, as determined by only one 

measurement, is 825 feet. From 100 to 200 

feet above the massive sandstone there is an 

exposure of carbonaceous sandstone and sandy 

shale containing woody fragments and impressions of poorly preserved stems which may 

represent the coal beds occurring in the Kootenai in the neighborhood of Great Falls or the 

corresponding Lakota of the Black Hills. No 

fossils were found in this part of the section 

during the season of 1916, but ·weed and 

Pirsson report that it contains Goniabasis sublaevis Meek and Hayden, Oorbicula cytheriformis 

Meek and Hayden, and an Ostrea. 

COLORADO GROUP. 

MOWRY SHALE. 

Above the Kootenai ( ~) formation is a wellmarked siliceous shale (fig. 2) which has been 

recognized at several localities and is the highest formation described by Weed and Pirsson 

in their paper on the geology of the Little 
26 SHOR.TER CONTRIBUTIONS TO GENERAL GEO.LOGY, 1918. 

Rocky Mountains. When freshly broken it is 

brown or black, but on weathering it becomes 

light colored and breaks into porcelain-like 

debris. It contains numerous fish scales and 

bones, some of which can be found on nearly 

every piece examined, and on some specimens 

the trails of small marine animals, probably 

crustaceans, were also found. Thin sections 

under the microscope show that the material 

of this shale consists of small, angular grains of 

quartz interbedded with a dark amorphous 

substance, probably carbon. Two distinct 

forms of Infusoria were seen, but their nature 

could not be determined in the material at 

hand. In appearance this shale resembles the 

shale of the Green River formation (Eocene) 

in Colorado and Utah, from which oil may be 

obtained by distillation, but a small fragment 

tested by distillation yielded only a trace of oil. 

On the basis of its lithologic similarity and content of fish scales, this shale is correlated with 

the Mowry shale, which occurs at several localities in Wyoming and southern Montana. 

Around the Little Rocky Mountains its outcrop is marked by a low ridge covered with 

pines. The thickness of the formation is about 

100 feet. 

COLORADO GROUP ABOVE THE MOWRY SHALE. 

Above the Mowry shale, in the region surrounding the Little Rocky Mountains, there is 

about 325 feet of dark-blue shale which differs 

slightly in color from the dark-gray gumbo 

shale higher in the section. The exposures are 

not continuous, and little can be said of the 

details of this part of the section. 

fossils found in it were baculites, a few of which, 

collected from limy concretions, were submitted 

to J. B. Reeside, jr., who reports upon them as 

follows: 

Baculites sp., usually referred to B. asper Morton. It is 

quite distinct from the related Pierre B. asper and from B. 

anceps obtusus. It has been collected from several localities in the Benton of Montana. (Collection 9841.) 

MONTANA GROUP. 

EAGLE (1) SANDSTONE. 

The sandstone that lies above the shale just 

described in the region surrounding the Little 

Rocky Mountains is marked by a ridge about 

30 feet high (fig. 2), the top of which is covered 

with large limestone concretions resting on 

sandstone. One poorly preserved specimen of 

Nernodon, referable to an undescribed species 

from the Claggett near Havre, was found (collection 9842). The same formation was seen 

at a locality about 3 miles southeast of the 

point where the section was measured, and 

although it was not closely studied it was 

thought to be about 100 feet thick. This 

sandstone is about 750 feet below the base of 

the Judith River formation, and if it is the 

Eagle sandstone it proves that the overlying 

formation varies a great deal in thickness, for 

the Eagle sandstone is described by Stebinger 1 

as being from 350 to 500 feet below the,base of 

the Judith River formation .. Reports of drilling northeast of Malta, in the Bowdoin dome, 

seem to indicat~ that the Eagle sandstol)e is 

not present there as a mappable unit. 

CLAGGETT SHALE. 

This shale is overlain by a sandstone capped The Claggett shale represents part of a 

by a foot or more of impure limestone contain- marine formation called the Pierre shale in 

ing fossil gastropods and pelecypods which have I regions to the east and southeast, which to the 

been identified by T. W. Stanton as of Benton west is represented by four formations-the 

age. J. B. Reeside, jr., who examined the ·Eagle sandstone, Claggett shale, Judith River 

collection, reports the following species: Callista formation, and Bearpaw shale. Of these formaorbiculata Hall and Meek, Pachymelania? sp. tions the Judith River is of fresh-water origin. 

undescribed, Amauropsis? sp. undescribed. The Claggett shale on the east side of the 

The stratigraphic position of this sandstone is Little Rocky Mountains, where its top and 

not far from that of the Frontier formation of bottom are exposed, measures approximately 

Wyoming and southern Montana. Its thick- 750 feet. In the center of the Bowdoin dome 

ness could only be estimated and is given in the north of ·saco about 500 feet of the upper part 

table as about 60 feet. of the formation is exposed. Stebinger, workThe sandstone noted above is overlain by ing in the vicinity of Havre, about 90 miles to 

about 875 feet of bluish-gray to black shale, the west, reports the thickness of this formation 

much of which is concealed and in which sandy 1 Stebinger, Eugene, Possibilities of oil and gas in north-central 

facies if present were not recognized. The only Montana: u.s. Geol. survey Bull. 641, p. sa, 1917. 
GEOL9GY OF NOR.THEASTER.N MONTANA. 27 

as frOin 350 to .300 feet. It consists of a darkgray shale which on weathering forms typi_cal 

gumbo soil. Scattered through the formatiOn 

in many places are concretions Qr masses of 

impure limestone, many of .which contain 

marine fossils, or of aragonite, a mineral resembling fossil wood. The formation also contains large flakes of selenite or transparent 

gypsum, and water in wells, springs, or small 

streams in the area of its outcrop is always 

more or less alkaline. This shale forms the 

lower slopes of the valley of Milk River betwee~ 

I-Iinsdale and Malta. Two collections of fossils 

fron1 it were referred to J. B. Reeside, jr., who 

identified one species, Baculites compressus Say, 

regarded as characteristic of the Pierre shale. 

About 70 feet of strata in the upper part of 

the Claggett shale appear to form a transition 

zone between the Claggett and the Judith 

River· formation. This zone is found on the 

west side of the Bowdoin dome, north of :Malta. 

On the north side of the dome, near Whitewater post office, it does not contain the characteristic sandstone, and it can not be recognized at all on the east side near I-Iinsdale. 

The following sections will illustrate this peculiarity: 

Sections of the transition zone of the Claggett and Judith 

Ri·ver formations. 

West or the Bowdoin dome nenr the center or T. 31 N., R. 30 E. 

Typical.Tudith River formation. Feet. 

Shale resembling the Claggett ..................... 50± 

Sandstone resembling Judith River formation containing abundant marine fossils .................. 20± 

Typical Claggett formation. 

70± 

North or the Bowdoin dome in Tps. 34 nnd 35 N., R. 32 E. 

Typical.Tudith River formation. 

Shale containing fossils similar to those of the marine 

sandstone of the preceding section ................ 50± 

Typical Claggett shale. 

The following lots of fossils collected from 

the upper part of the Claggett shale have been 

identified by Mr. Reeside, who finds that they 

are marine forms characteristic of the Pierre 

shale. 

lOOHi. Sec. 32, T. 35 N., R. 32 E.: 

Lunatia subcrassa Meek and Hayden. 

10017. Sec. 25, T. 33 N., R. 30 E.: 

Tancrediaame1·icana Meek and Hayden (fragments): 

Lunatia subcrassa Meek and Hayden. 

9829. North half ofT. 31 N., R. 30 E.: 

Cardium speciosum Meek and Hayden. 

Tancredia americana Meek and Hayden. 

Lunatia subcrassa Meek and Hayden. 

Haminea subcylindrica Meek and Hayden. 

9830. Western part ofT. 31 N., R. 30 E., south of Assinniboine Creek: 

Anatina sp. undescribed. 

Mactra alta Meek and Hayden. 

Tancredia americana Meek and Hayden. 

Cardium speciosum Meek and Hayden. 

Anchuria sp. undet. 

Lunatia subcrassa Meek and Hayden. 

Placenticeras intercalare Meek. 

Baculites compressus Say. 

JUDITH RIVER FORMATION. 

Above the Claggett shale lies the Judith 

River formation, esttmated from several imperfect measurements to range from 400 to 425 

feet in thickness. The outcrop of this formation surrounds the Bowdoin dome, standing 

out as a light-colored formation in the 

hill south of the railroad from Malta to 

Vandalia and north· of the railroad near Valleytown and Lovejoy. It also crops out in 

one of the surrounding sandstone ridges of the 

Little Rocky Mountains. It probably extends 

east of the Bowdoin dome beneath the surface, 

at least as far as the mouth of Milk River, 

where it has probably been reached in an artesian well at a depth of 7 50 feet .. To the southeast the Judith River formation is not recognizable as a distinct unit, as shown by the gas 

wells sunk on the Glendive anticline. A characteristic view of the Judith River formation 

is given in Plate III, A. The formation con-

-sists of extremely variable beds of hard brown 

sandstone, soft, friable light-colored sandstone, and light-gray shale; and on account of 

their variability no beds·were found that. would 

serve as horizon markers. In describing this 

formation Stanton and I-Iatcher 1 say: 

A detailed section taken at any point is of little value, 

since a similar section made at a distance of only a mile or 

two would give a quite different sequence of the alternating strata of sandstones and shales. 

Some of the details of this formation may be 

seen from two sections which were measured 

in its upper part on the east side of Rock Creek, 

as follows: 

1 Stanton, T. W., and Hatcher, J. B., Geology and paleontology or 

the Judith River beds: U.S. Geol. Survey Bull. 257, p. 34, 1905. 
28 SHORTER .CONTRIBUTIONS TO GENERAL G~OLOGY, 1918. 

Sections of part of the Judith River formation. 

Shale, brown ................................... . 

Feet. 

On east canyon wall of Rock Creek, in.sec. 20, T. 34 N., R. 36 E. Lignite .............. : ........................... . i 

t 

Bearpaw shale above Judith River formation. 5 

Sandstone, massive, grayish, with iron concretions 

scattered or in beds; weathers yellowish; some 

red bands cross-bedded ........................ . 

Shale, brown, in places approaching lignite ....... . 

S~nd_stone, soft, yellowish g~ay, and gray shale ... . 

Lignite .......................................... . 

Shale, brown ................................. · .. . 

Shale, gray .................................. _ .. . 

.,. Shale, dark, carbonaceous ....... · ................ . 

Shale, gray, and sandstone ................. .- ..... . 

Lignite ............................................ . 

Shale, brown ................................... . 

Shale, gray ............. _ ....................... . 

Shale, brown ......................... · .............. . 

Sanstone, soft, with iron concretions ............... . 

Shale, sandy, brown ............................. . 

Sandstone, soft, gray ..................... · ........ . 

Clay, shale gray ................................. . 

Shale, brown ................................... . 

Sandstone, soft, gray, and sandy shale ............. . 

Sandstone, concretion bed ...... , ................. . 

Shale, soft, sandy, gray ........................... . 

Sandstone, iron-concretion bed ................ : .. . 

Shale, blue and gray ......... .' ................... . 

Concretions ...................................... . 

Shale, gray ..................................... . 

Shale, brown ........................ : .......... . 

Sandstone, soft, gray and yellow .........•........ 

Sandston~, massive; weathers brown; arkosic, containing much feldspathic and feriomagnesian 

materiaL This bed forms conspicuous ledges .... 

Sandstone, soft, gray; some shale~ ..•.............. 

Base of formation not exposed. 

Feet· 

32 

2 

23 

~ 

1 

Sh~le, brown ................................... . 

Shale, blue-gray ................................ . 

Shale, brown ................................... . 

Shale, sandy ..... .' .............................. . 

Sandstone, concretions .......................... . 

Shale, gray .................. _ .. _ ............... . 

Sandstone, soft, gray ............................. . 

Shale, dark .................... _ ................ . 

4 ·Sandstone, soft, gray, and sanely shale ............. . 

i Shale, brown ................................... . 

5 Sandstone, massive, soft, gray or yellowish, weath-

! ering yellowish; certain beds weather out as masi sive reddish layers or as huge concretions; shows 

G some cross-bedding ............................. . 

3 

1 

2 

6 

4 

3 

9 

1 

5 

1 

4 

1 

4 

2 

17 

7 

20 

165 

Base of formation not exposed. ' 

12 

1 

6 

1 

10 

13 

3 

14 

2 

101± 

296± 

East canyon wall of Rock Creek, near line between sec. 32, T. 34 N., 

R. 36 E., and sec. 4, T. 33 N., R. 36 E •. 

The base of this formation is not very definitely marked and can not everywhere be 

separated from the upper part of the Claggett 

shale; but its top can be readily recognized in 

the few places· where it is well exposed. The 

upper part of the Judith River formation consists of a massive sandstone in the two sections 

cited and in the neighborhood of the Little 

Rocky Mountains, and is overlain by characteristic Bearpaw shale. At other places in the 

region the massive sandstone is not prominent, 

and in one or two localities a small bed of lignite 

within a few feet of the top has been mined. 

Stanton and Hatcher report a layer of shell 

brec'cia consisting of shells of Ostrea subtrigonalis 

near the top of the Judith River formation as its 

most persistent horizon marker, but such beds 

were not seen in the neighborhood of the 

Bowdoin dome. Invertebrate fossils collected 

from the formation during the season of 1916 

have been examined by Mr. Reeside, who reports that six lots consist of marine forms and 

one lot from the flanks of the Litt]e Rocky 

Mountains contains fresh-water forms of Judith 

River types. The species identified are as 

follows: 

Glacial gravel. Feet. 

Sandstone, massive, gray; w~athers yellow or reddish; some thin beds; cross-bedded ........... ·.. 47 

Shale, gray....... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 

Sandstone, soft, gray ............................ . 

Shale, gray ...................................... . 

Shale, brown ................................... . 

Shale, gray .................................... ~ . 

Shale, brown ....... ~ .......................... :. 

Sandstone, soft, gray ............................. . 

Shale, brown, with 3 inches of lignite ......... : ... . 

Shale, gray ..................................... . 

Shale, brown ................................... . 

Shale, blue ...................................... . 

Sandstone, soft .............................. ' ... .-

Shale, brown ................................... . 

Sandstone, soft, gray ............... · .............. . 

Shale, blue-gray ................................ . 

Concretions ...................................... . 

Sandstone, soft, massive, gray .................... . 

2 

4 

3 

2 

1 

5 

2 

5 

6 

2 

9 

1! 

.3 

5 

6 

18 

9826. Sec. 36, T. 33 N., R. 37 E., on road: 

Plates of an undescribed barnacle. 

Tancredia americana Meek and Hayden. 

Cardium speciosum Meek and Hayden. 

Protocardia sp.?, large form. 

Mactra sp.? 

Inoceramus sp. ?, very young individual. 

Nucula sp.? 

Lunatia subcrassa Meek_ and Hayden. 
GEOLOGY OF NORTHEASTERN MONTANA. 29 

982G. Sec. 3G, T. 33 N., R. 37 E., on road-Continued. Sections of Judith River formation in northeastern Montana. 

Of. Trachytriton vinculum Meek and Hayden. 

Scaphites sp., fragment suggesting S. nic?lleti 

Morton. 

Baculites sp.?, fragment. 

Most of this lot consists of casts lacking essential 

details. The Protocardia?, Lvnatia, and Scaphites suggest Bearpaw rather than typical Judith River. 

984B. SvV. t sec. 21, T. 33 N., R. 37 E., on Eagle Creek; 

upper part of Judith River formation: 

Liopistha. undata Meek and Hayden. 

Pteria nebrascana Edwards and Solander. 

Marine; Pierre fauna. 

41. Sec. 4, T. 33 N., R. 37 E., on Bitter 0reek; upper part 

of Judith River formation: 

Natica sp.? 

Mactra sp.? 

Serpula sp.? 

The only fresh-water forn1s are found in the 

following lot: 

9837. See. 21, T. 25 N., R. 26 E., sandstone about middle 

of Judith River formation at east end of Little Rocky 

:Mountains: 

Unio cf. U. primaevus White. 

Unio cf. U. suprag~bosus Whiteaves. 

This lot consists of fragments which suggest a reference 

to the Judith River but are too poor to be conclusive 

Unig supragibbosu.s occtus in the Canadian Belly River 

and in the Judith River formation. U. primaevtt.s is a 

.Tuclit:h River species. 

Inasn1uch as this lot of fresh-waterforms is 

from the 1niddle of the formation, while the 

1najority of the fossils found are marine, it is 

probable that the Judith River formation of 

this area is marine at the top and bottom. 

Bones of fresh-water dinosaurs were collected 

at several localities and were examined by C 

W. Gihnore, of the National Museun1, who 

f~und then1 too fragmentary for specific determination. 

' 

Specirnens of petrified wood,· described by 

F. I-I. l{nowlton as that of cone-bearing trees 

were collected at several places in the Judith 

River formation, but no deterrpinable fossil 

leaves were found. 

This forn1ation contains small lenticular beds 

of lignite or subbituminous coal which are too 

thin to be of value. Local n1ines fron1 which 

the farmers have obtained a small amount of 

fuel were examined at the points where the following sections were measured: 

28288°-19-3 

I 

Location. 

Sec.· T.N. R.E. 

----

21 33 37 

------ 4 33 37 

-

------

5 33 37 

------ 15 32 37 

------ 1G 32 37 

------ 7 34 3() 

------

12 34 35 ------ 32 34 35 

------ 6 33 35 

------ 20 34 34 .. 

------ 5 35 34 --

9 351 34 

9 28 32 ------ 9 28 34 

Section. 

Ft. in. 

Bearpaw· shale. Sand~~o~e ................... 20± 

Ligmte ................. 8 

Sandstone and shale ........ 15± Slu~Je,_ carbonaceous, and 

hgmte .................... 2± 

Bearpaw shale. 

Sandstone and shale ......... 59 0 

Lignite ................. 6 

Sandstone and shale ........ 22 . 0 

Shale, carbonaceous ........ 2 0 

Lignite .................. 8 

Shale, carbonaceous ........ 2 0 

Shale, blue ................ 4 6 

Shal~, <:arbonaceous ........ 6 

Lignite ................. 1 2 

Shale, carbonaceous ...... ,· . 6 

Sandstone .................. 10 0 

Lignite ............ · ..... 1 4 

Shale, sandy gray .......... 3 0 

Lignite, a few inches. 

Shal~, g:ay ................. 5 0 

Lignite .................. 1 4 

Shale, brown ............... 1 0 

Ligt;1ite ..... ~ ............ 6 

Shale, gray ....... · ...... ! ~ .. 5 ·0 Shal~, b_roW'n ............... 2 

Ligmte ................. 8 

Shale, brown ............... 4 

Shale, gray. 

Shal~, g_ray ................. 5 0 

Ligmte ................. 10 

Shale, brown ............... 8 

Shale, gray. 

Shale ........ · ............... 10 0 

Lignite ................. 6 

Shale, bro:wn. 

Shale, gray ................. 1+ 

Lignite ................. 6 

'Lignite .................. 8 

Lignite ................. 6-10 

Bearpaw shale. 

Judith River formation ..... 50± 

Clay,_ bl~ck, carbonaceous .. 1 6 

Lignite ................. 10 
30 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

BEARPAW SHALE. 

The Bearpaw shale, from 800 to 1,000 feet 

thick is, as shown on Plate I, the most widespread formation exposed in the region described, and overlies the Judith River formation. It consists essentially of dark-gray shale 

which forms a gumbo soil and presents an uninteresting and monotonous landscape. This 

shale is exposed in many places along escarpments and canyons and forms badlands which 

lack the variety due to the presence of harder 

beds. A characteristic view of the badlands of 

the Bearpaw shale is given in Plate III, B. The 

fossils are all of marine types; Baculites, Inoceramus, and oysters are very abundant,·and occasionally the remains of a gigantic marine saurian 

are found. The formation in places contains 

limy concretions, in which the lime 'is in the 

form of aragonite showing cone in cone structure or appearing like the stu:mps of large trees. 

Calcite also is present in many of these concretions, and smaller masses of barite were 

noted in several localities. The formation contains more or less gypsum, which at some 

places is transparent and at others occurs in· 

uncrystallized forms replacing the calcite of 

oyster shells. The water from the Bearpa w 

shale, like that· from the Claggett, is usually 

alkaline. 

The following invertebrate fossils were collected during the field season of 1916 and were 

identified by J. B. Reeside,_ jr.: 

9825. SW. t sec. 22, T. 33 N., R. 37 E.: 

Inoceramus sagensis Owen. r 

Heteroceras sp. related to H. newtoni Meek but 

probably undescribed. 

Pierre fauna; fossils not distinctive of Bearpaw shale. 

9827. Sec. 36, T. 36 N., R. 36 E.: . 

Ostrea patina Meek and Hayden. 

So far as known this form is confined to the Bearpaw 

shale. 

9828. Sec. 5, T. 36 N., R. 26 E.: 

Chlamys nebrascensis Meek and Hayden. 

Baculites compressus Say. 

Of. Trachytriton vinculum Say. 

Membranipora sp. undescribed (identified by R. S. 

· Bassler). 

Pierre fauna. 

9838. Sec. 21, T. 25 N., R. 26 E.: 

Ostrea patina White 

9839. Sec. 21, T. 25 N., R. 26 E.: 

Inoceramus sagensis Owen. 

Baculites sp., fragments. · 

Pierre fauna. 

10020. Sec. 10, T. 23 N., R. 36 E., 150 to 200 feet below 

top of Bearpaw shale: 

Scaphites nodosus var. plenus Meek. 

Baculites compressus Say. 

Cyprimeria? sp., single weathered individual. 

Pierre fauna. 

10021. Southwestern part of T. 23 N., R. 36 E., 50 to 100 

feet below top of Bearpaw shale: 

Baculites compressus Say. 

Pierre fauna. 

10024. Northeastern part ofT. 23 N., R. 34 E., 50 feet below top of Bearpaw shale, -on Timber Creek: 

Baculites compressus Say. 

Pierre fauna. 

10025. T. 26 N., R. 34 E., along Larb Creek; middle of 

Bearpaw shale: 

Baculites sp., fragments. 

Pierre fauna. 

10028. T. 24 N., R. 41 E., near top of Bearpaw shale: 

Inoceramus sagensis Owen. 

Protocardia subquadrata Edwards and Solander. 

Anomia sp., fragments. 

Y oidia evansi Meek and Hayden. 

Lunatia sp., fragments. 

Dentalium gracile Meek and Hayden. 

Anch~ sp., fragment. 

Actaeon attenuatus Meek and Hayden. 

Scaphites sp., probably young S. nodosus plenus 

Meek. 

Bearpaw shale. 

Parts of skeletons of two large marine reptiles 

collected in this region, one found several 

years ago by Ira Taylor, were submitted to 

C.· W. Gilmore, who identified one of them 

(from sec. 23, T. 37 N., R. 35 E.) as consisting 

of numerous parts of vertebrae, limb bones, 

fragmentary teeth, jaws, and other fragments 

of a large plesiosaurian reptile; and the other 

(from sec. 23, T. 34 N., R. 38 E.) as consisting 

of numerous vertebrae and other parts of the 

skeleton of a mososaurian reptile. Neither of 

these forms was otherwise determinable. The 

remains of both animals are found only _in. 

marine or brackish-water formations 

TERTIARY (1) SYSTEM. 

LANCE FORMATION. 

The Lance formation, which overlies the 

Bearpaw shale, as here identified, is composed 

of two more or less distinct members in the 

eastern and southern parts of the region 

described. In the northwestern part, in the 

Cherry Ridge quadra:ngle, the exposures are 

too meager to indicate their character. 
GEOLOGY OF NOR.THEAST'ERN MONTANA. 31 

The lower member has been described by 

Dawson,t who estimated the thickness at 80 

feet a.nd referred it to the Fox Hills sandstone. 

Figure 4, reproduced fr01n Dawson's report, 

shows ~he relation of the two members near 

the international boundary northwest of 

Opheim. The lower n1ember is here composed 

of yellowish and rusty sands grading into 

arenaceous clay toward its base. It is characterized by large, irregular sandy concretions 

which in places approach a more or le~s sphericnl form and are slightly darker than the pre-

.vniling color of the for1nation. So far as the 

writer knows 1narine fossils have not been 

obtained from this member within the region 

described. Rose/ in his description of beds 

he designated Fox Hills sandstone in the 

Wood J\1ountain district of Canada., gives a 

list of the fossils found by R. G. J\1cConnell in 

beds designated Pierre anq. Fox Hills formaSouth Dakota. Small exposures of this member are found in T. 37 N., R. 40 E., and T. 35 

N., R. 44 E., where it is similar in lithologic 

character to the rocks northeast of Opheim. 

In the Larb Hills, in the southern part of the 

region described, a similar ·n1ember having a 

thickness of. about 100 feet where measured 

in sec. 13, T. 24 N., R. 32 E., rests upon the 

Bearpaw shale and is capped by a harder 

sandstone. The same succession of beds is 

exposed south of J\1issouri River, where Brown 3 

reports collecting i4 species of marine invertebrate fossils, identified as the Fox Hills fauna, 

from concretions found on Hell Creek. l-Ie 

further reports ~ that in the san1e valley, 20 

feet below the base of the sandstone he calls 

Fox Hills, the r~mains of a large trachodont 

dinosaur were discovered. The specimen was 

found in place partly embedded in a large 

calcareous concretion that was weathered out 

FiouuE 4.-8ection in badlands south of Wood Mountain, Saskatchewan, Canada, showing the relation of Fort Union formation (a), upper 

part of Lance formation (b), lower part of Lance formation (c), and Bearpaw shale (d). 

tions in the Cypress Hills, but as no effort is 

n1ade to distinguish between the formations 

the list is probably of little value. 

A very good exposure of yellowish sandstone, resen1bling that at the boundary, covers 

2 or 3 square miles in and around sec. 34, T. 

36 N., R. 39 E. In this sandstone, which 

surely lies only a short distance abQve the 

Bearpaw shale, was found a well-preserved 

fossil bone which Gilmore identified as "the 

proxin1al half of the left ischium of a trachodont 

dinosaur. So far as it can be ·compared it 

appears identical with the same element in 

Trachodon annectens J\1arsh, from the Lance 

formation." The finding of this fossil justifies 

the belief that the lower prert of the Lance is a 

fresh-water deposit and should not be classified 

as the Fox Hills sandstone, which in the type 

locality is marine. It may, however, be conteinporaneous with the Fox Hills sandstone of 

1 Dawson, G. M:., Geology or tho 49th parallel, British North American 

Boundary Commission, Montreal, 1875. 

ll Rose, Bruce, 'Vood Mountain-Willowbunch coal areas, Saskatchewan: Canada Gool. Survey Mem. 89, p. 32, 1916. 

and broken. The humeri were still covered 

with shale and well preserved. 

This member northwest of Opheim is probably the same as that found on J\1issouri River 

in the southeastern part of the region here 

described and called the Fox Hills sandstone 

by Smith. 5 (See Pl. IV, A.) It is described 

in a later report by Beekly 6 as the Colgate 

sandstone member of the Lance formation, 

consisting of 50 to 150 feet of buff sandstone 

interstratified with somber-colored and yellow 

clay. The type locality is the vicinity of Colgate station on the Northern Pacific Railway, 

described by Calvert;7 

The upper member of the Lance formation is 

composed of shale and argillaceous sandstone 

and is characteristically of somber color. Its 

a Brown, Barnum, The Hell Creek beds of Montana: Am. Mus. Nat. 

Hist. Bull. 23, p. 827, 1907. 

4 Idem, p. 826. 

5 Smith, C. D., The Fort Peck Indian Reservation lignite field, Mont.: 

U.S. Geol. Survey Bull. 381, p. 42, 1908. 

o Beekly, A. L., The Culbertson lignite field, Valley County, Mont.: 

U. S. Geol. Survey Bull. 471, pp. 329, 330, 1912. . 

7 Calvert, W. R., Geology of certain lignite fields in eastern Montana: 

U. 8. Geol. Survey Bull. 471, pp. 194, 195, 1912. 
• 

32 SHORTER CONTRIBUTIONS TO GENERAL GEQLOGY, 1918. 

foot bones, vertebra, chevrons, etc., of Thescelosaurus 

neglectus Gilmore; caudal vertebra of a carnivorous dinosaur, not determinable; two fragments of a turtle shell, 

probably pertaining to the genus Aspidontes. The presence of Thescelosaurus neglectus would indicate that these 

fossils came from the Lance formation, for the four or five 

specimens of the genus known at this time are all from 

the Lance. 

A single vertebra collected near the top of 

the ·Lance formation in sec. 27, T. 37 N., R. 

46 E., is that of Ohamposaurus sp., characteristic of both.the Lance and Fort Union formations. 

Several small collections of invertebrate 

fossils, made in the Larb Hills, have been identified by Mr. Reeside as follows: 

10022. Sec .. 29, T. 24 N., R. 35 E. 

Unio brachyopisthus. 

Unio holmesianus. 

1 Brown, Barnum, op. cit., pp. 823-845. 

10023. Sec. 29, T. 24 N., R. 35 E. 

Unio cf. U. brachyopisllms White. 

Sphaerium subellipticum Meek and Hayden . 

• Viviparus sp., fragment. · 

10026. Sec. 29, T. 24 N., R. 3·5 E. 

Tulotoma thompsoni White. 

10027. Sec. 25,. T. 25 N., R. 34 E. 

Sphaerium subellipticum Meek and Hayden. 

Campeloma multilineata Meek and Hayden. 

All are probably from the Lance formation. 

Fossil wood from the Lance formation has 

been identified by Knowlton as that of coniferous trees, but no identifiable fossil plants were 

collected. 

TERTIARY SYSTEM. 

2 Rose, Bruce, Wood Mountain-Willowbunch coal areas, Saskatchewan: Canada Geol. Survey Mem. 89, pp. 69-83, 1916. Bauer, C. M., 

Clay in northeastern Montana: U. S. Geol. Survey Bull. 540, pp. 369-372, 

1914. 

a Beekly, A. L., The Culbertson lignite field, Valley County, Mont.: 

U.S. Geol. Survey Bull. 471, pp. 326, 331, 1912. 

• 4 Rogers, G. S., The Little Sheep Mountain coal field, Dawson, Custer, 

and Rosebud counties, Mont.: U. S. Geol. Survey Bull. 531, pp .. 12, 13, 

1913. 
• 

U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER" 120 PLATE IV 

A. LOWER PART OF THE LANCE FORMATION, SHOWING 

SPHERICAL CONCRETIONS. 
U. S. GEOLOGICAL SURVEY PROFESSIONAT, PAPER 120 PLATE V 

B. EROSION FORM OF LANCE FORMATION. 
GEOLOGY OF NORTHEASTERN MONTANA. 33 

Union formations exposed from Redstone to 

Plentywood (Pl. I) is much generalized: 

Generalized section of the Lance and Fort Union formations 

between Redstone and Plentywood, Mont. 

Fort Union formation: Ft. in. 

Sandstone and shale ..................... . 81 0 

J_,ignite ..................... -........ · 6 

Sandstone and shale ..................... . 67 0 

Shale ................................... . 52 0 

Lignite, Richardson bed .............. . 6± 

Sandstone and shale more or less concealed 320± 

Lignite, upper Eagles Nest bed ..... : . 6 3 

Shale and sandstone, yellowish .......... . 50± 

Lignite, lower Eagles Nest bed ...... . 4 0 

Shale and sandstone, yeilowish .......... . 70 0 

Lignite ............................ . 10 

Shale and sandstone, yellowish .......... . 19 0 

Lignite .• : ........................... . 1 2 

Shale and sandstone, yellowish .......... . 18 0 

Lignite •.•.......................... 4 

Shale, grading upward into sandstone, 

yellowish ............................ . 20 0 

Lignite ............................ . 

Shale I1nd sandsto~e, yellowish .......... . 

1 6 

60± 

Lignite, Redstone bed ............... . 6 0 

Shale and sandstone, yellowish .......... . 22 0 

Lignite ............................ . 2 0 

Lance formation: 

Shale and sandstone, somber color ..... . 30 0 

Lignite ............................ . 1 10 

Shale and sandstone, somber color ..... . 27 0 

!.ignite ............................ . 6 0 

872± 

Tl1e following generalized section of the Fort 

Union and its lignite beds as exposed on Missouri River in the southeastern part of the 

region is taken from Beeldy's report: 1 

Generalized sect·ion showing the distribution of lignite beds 

~·n the Fort Unionformation. 

Culbertson field, 2 miles cast or Lakeside. 

Ft. in. 

Sandstone with some shale ................... . 

Lignite .................................. . 

Sandstone and shale ......................... . 

Lignite, bed DD ........................ .. 

Sandstone and shale .......................... . 

Lignite, bed CC ......................... . 

Sandstone and clay ........................ . 

Lignite ................................ . 

Fort Peck field west or Big Muddy Creek. 

[C. D. Smith, 1908.1 

Clay ....................................... . 

Lignite, bed D .......................... . 

Sandstone and clay ........................ . 

Lignite, bed C ......................... . 

Sandstone ancl clay ........................ . 

Lignite, bed B ......................... . 

Sandstone and clay .... , ................... . 

Lignite ................................ . 

Clay ....................................... . 

Lignite, bed A .. · ..... ~ ................. . 

Somber-colored beds (Lance). 

Ft. in. 

121 0 

1 0 

24 o' 

4 4 

70 0 

2 5 

130 0 

5 7 

416 8 

6 0 

9 0 

95 0 

2 0 

115 0 

3 0 

275 0 

5 0 

15 0 

7 7 

532 7 

1,390_ 3 

The following section, measured in sec. 18, T. 

24 N., R. 33 E., shows the relations of the Fort 

Union, Lance: and Bearpaw formations in the 

Larb Hills: 

Section showing the relation of the Fort Union, Lance, and 

Bearpaw formations in the Larb Hills, },font. 

Fort Union formation: Ft. in. 

Sandstone, yellowish ................... . 50 0 

Lignite ............. · ............... . 3 

Sandstone, soft, yellowish .............. . 20 0 

Lignite ............................ . 1 0 

Sandstone, soft, yellowish .............. . 11 0 

Lignite ............................ . 1 0 

Sandstone, soft, yellowish .............. . 20 0 

Lignite ............................ . 6 0 

109 3 

Clay and shale .............................. . 125 0 Lance formation: 

Lignite, bed IT ......................... . 

Clay and shale .............................. . 

Lignite, bed G ........................... . 

Clay and sanely shale ......................... . 

I ... ignite .................................. . 

Sandstone and clay .......................... . 

! .. ignite .................................. . 

Sandstone and shale ........................ .. 

Cu.lbcrtson field, sec. 3, T. 27 N., R. 56 E. 

Lignite, bed F .... -...................... . 

Sandstone and shale ......................... . 

Lignite, bed E ........................... . 

1 Beckly, A. L., op. cit., p. 331. 

4 o Shale and sandstone, somber color ........ . 50 0 

70 0 Lignite.~ .......................... . 6 

4 0 Shale and sandstone, somber color; con150 0 tains dinosaur bones ................... . 100 0 

1 10 Concealed .............................. . 100 0 

30 0 Shale, sandy ............................ . 100 0 

1 2 Bearpaw shale. 

55 0 350 6 

441 0 459 9 

The relations of these sections are shown 

gra.phically in figure 5. 

7 o Full descriptions of the lignite beds in each 

45 0 .township are given in other reports.2 

6 4 

2 U. S. Geol. Survey Bull. 381, pp. 40-59, 1910; Bull. 471, pp. 319-358, 

1912; Bull. 541, pp. 293-315, 1914; and a report not yet publish!)d. 
34 SHORTER CONTRIBUTIONS T'O GENERAL GEOLOGY, 1918. 

The following small collections of fossil 

plants have been examined by F. I-I. Knowlton, 

who reports that they are of Fort Union age: 

7001. Sec. 3, T. 35 N., R. 44 E.: 

Sequoia nordenskioldii Heer. 

A 

Richardson bed 

Upper Eagles Nest 

Lower Eagles Nest 

Redstone bed 

Contact 

B 

Bed H 

Bed G 

Bed F' 

Bed E 

Bed DO 

Bed CC 

Bed D. 

Bed C 

Bed B 

Bed A 

Onoclea sensibilia fossilis Newberry. 

Trapa microphylla Lesquereux of Ward. 

Selaginella collieri Knowlton,• n. sp. 

J?otamogeton n. sp. · 

7005. Canada, near the north line of sec. 4, T. 37 N., R. 

49 E.: 

c l Ft. Union formation 

(sandstone, shale. and 

lignitej yellow beds) 

Phillips bed 

Thin bed 

Lance formation Lance formation 

Colgate(?)sandstone 

member 

100 0 100 

Colgate sandstone me.:nber 

200 300 400 soo Feet 

Lance formation 

(somber sandstone and shale, 

·and lignite above) 

Yellow sandstone and shale 

(Colgate(?)sandstone member) 

Bearpaw shale 

FIGURE 5.-Generalized sections of Fort Union anc;l Lance formations, showing their relation to the Bearpaw shale from its outcrop northwest of 

Opheim to Plentywood, Mont. (A); north of Missouri River from Brockton to the Dakota line (B); and in the Larb Hills, in T. 24 N., R. 33 

E.(C). 

Glyptostrobus ungeri Heer. 

Dicotyledon, gen. and sp.? 

7002. NE.!sec. 31, T. 36 N., R. 45 E.: 

Sequoia nordenskioldii Heer. 

7004. Sec. 33, T. 37 N., R. 47 E.: 

Alga. 

Onoclea sensibilis fossilis Newberry. 

Taxodium occidentale Newberry. 

Sequoia nordenskioldii Heer .' 

Platanus sp. 

1 Knowlton, F. H., A new fossil Selaginelb from the lower Tertiary of 

Montana: Torreya, vol. 16, pp. 101-:1U3, 1916. 
GEOLOGY OF NORTHEASTERN MONTANA. 35 

7505. Canada, near the north line of sec. 4-Continued. 

Grewia sp. · 

Persea sp. 

7006. SE. i sec. 21, T. 36 N., R. 52 E.: 

Taxodium occidentale Newberry. 

Sequoia no_rdenskioldii Heer. 

Grewia pealei Ward. 

7272. NE. t sec. 36, T. 37 N., R. 3~ E.: 

Sequoia nordenskioldii Heer. 

Glyptostrobus europaeus Unger. 

Fragments of a dicotyledon. 

Collections of invertebrates, on which T. W. 

Stanton has reported, were made at. the following localities: 

9837. SW. t sec. 6, T. 35 N., R. 45 E.: . 

Unio ep. fragments. 

Campeloma producta White. 

Campeloma multilineata Meek and Hayden. 

Fort Union. 

9380. T. 36 N., R. 46 E.: 

· Vivipu.rus sp. 

Probably Fort Union. 

9381. Sec. 13, T. 3.4 N., R. 50 E.: 

Unio sp. 

Campeloma multilineata Meek and Hayden. 

Fort Union. 

FLAXVILLE GRAVEL. 

With the Fort Union the conformable series 

stops, and the formations representing the later 

history of the region are surficial deposits of 

rather small extent laid down during favorable 

intervals between great time breaks when 

erosion was prevalent and no sediments were 

deposited. 

The Flaxville gravel, 1 shown in several areas 

along the international boundary, is a few feet 

to lOO.feet thick and caps a series of plateaus 

upon eroded surfaces of the Fort Union, Lance, 

nnd Bearpaw formations at altitudes ranging 

from 2,600 feet at the east end to 3,200 feet 

at the west end of the region described, near the 

international boundary. It is composed of 

gravel, sand, clay, volcanic ash, and marl·and 

in places ia cemented with calcite. The gravel 

consists of pebbles derived from the quartzite 

m~d argillite of the Rocky Mountains. 

Fragments of fossil.vertebrates found at 25 

wic}.ely distributed localities have been submitted to J. W. Gidley, who states that the 

beds which contained them can not be older 

than Miocene or younger than early Pliocene 

and that they are probably upper Miocene. 

1 Collier, A. J., and Thom, W. T., jr., Tho Flaxville grovel and its 

relation to other high torroco grovels of tho northern Groat Plains: U.S. 

Gool. Survey Prof. Pupor 108, pp. 179-184, 1917 (Prof. Paper 108-J). 

The time break between the Fort Union formation (Eocene) and the Flaxville gravel (Miocene) is in part represented by the Oligocene· 

deposits found on a still higher plateau in the 

Cypress Hills in Canada, 50 miles away. 

TERTIARY OR QUATERNARY SYSTEM. 

LATE PLIOCENE OR EARLY PLEISTOCENE 

DEPOSITS'. 

Below the Flaxville level there are extensive 

areas across which the present streams have 

eroded valleys from 100 to 500 feet in depth. 

Stratified silt and gravel are to be found in a 

very few places on this level, and from one df 

these exposures of gravel in sec. 23, T. 33 N., 

R. 35 E., a single fossil tooth was collected 

which Dr. Gidley identified as that of a horse 

resembling the living species. As the gravel 

from which it came is clearly older than the 

last advanoo of ice during the glacial epoch, the 

formation is regarded as of either late Pliocene 

or early Pleistocene age. 2 

Extensive benches slope gently away from 

the Little Rocky Mountains at several levels. 

These benches are capped with gravel containing many pebbles of limestone and porphyry 

derived from the neighboring mountains and 

are almost surely of Tertiary age, for in some 

places the gravel on them is overlain by glacial 

drift. The lowest bench is probably equivalent 

to the late Pliocene or early Pleistocene bench 

in the region north of Milk River with which 

it is tentatively correlated. The presence of 

undissolved limestone pebbles seems to forbid 

the assignment of these benches to an. earlier 

period. 

QUATERNARY SYSTEM. 

ALLUVIUM: 01'' PREGLACIAL RIVERS. 

Since late Pliocene or early Pleistocene time 

streams have been at work eroding the pre~ent 

valleys. The effects of this erosion can be seen 

in the escarpments north and south of Milk 

River between Tampico and Malta, where at 

one place 300 feet of beds belonging to the 

Claggett and Judith River formations, capped 

by late· Phocene or early Pleistocj3ne gravel, 

are exposed. The cutting of the river valley 

must have occurred early in Pleistocene time, 

when the valley of :Milk River was occupied by 

s Idem, p. 18Z. 

c 

• 
0 

• 

36 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

·~ much larger river, the Missouri/ and along 

ItS banks and flood p1ains gravel, silt, and 

sand were ·deposited. Some of this material 

·can be :aeen in pits northwest of Saco and north 

of Malta. The gravel ·here differs from the 

Flaxville grayel in that it contains numerous 

fragments of porphyry. 

Similar deposits occur at several points in 

the first benches above the flood plain of the 

Missouri between Milk River and the North 

Dakota line, and are best exposed where gravel 

pits are operated by the Great Northern Railway. In the summer of 1917 a pit was operq.ted at Wolf Point, where a new freight division of the railway was being installed and 

where the photograph reproduced in Plate 

VI, B, was taken. Wolf Point lies about 25 

feet above the Missouri, and the gravel pit is 

in the second bench, about 20 feet higher. 

;The section exposed is about as follows: 

Section exposed in gravel pit at Wolj.Point. 

S ·1 · h . Feet. 01 , w1t a few scattered granite boulders on the 

surface........................................ 1 

Glacial till, containing granite cobbles............. 5 

Gravel, chiefly quartzite but containing fragments 

of sandstone, porphyry, and near.the bottom shale. 13 

Shale, Bearpaw. 

19 

The gravel is interstratified with lenses of 

sand, and the bedding planes are ne::trly .horizontaL · The gravel consists for the most part 

of .well,..rounded pebbles of .quartzite, probably 

derived, from the Flaxville gravel, but it contains some pebbles of porphyry and fragments 

of sandstone and of fossiliferous Bearpaw shale 

near the bottom. A thorough search failed to 

reveal any .glacial material $Uch as granite 

pebbles. It was evidently deposited by Missouri River in preglacial time, for it is overlain 

by glacial till containing many more or less 

.angul~r frag_ments of granite. Another gravel 

pit 2 miles west of Brockton shows finely laminated sand. The bedding at the west end of 

the pit hes nearly horizontal, whereas that at 

the east end dips east about 70°. The surface has been eroded irregularly and is covered 

with glacial till to a maximum depth of about 

15 feet. The bottom of this pit is about 40 

feet above the present river level. 

1 Calhoun, F. H. H., The Montana lobe of the Keewatin ice sheet: 

U. S. Geol. Survey Prof. Paper 50, pp. 34-45, 1906 . 

GLACIAL MORAINES AND DRIFT. 

Overlying the gravel in the Milk River 

valley as well as the Flaxville gravel and all 

the higher benches described there is in manv 

places a sprinkling of glacial poulders, among 

which specimens of limestone from Lake Winnip_eg and of granite from the Hudson Bay 

regiOn are abundant. One large limestone 

erratic about 20 feet long was found by 

W. C.· Alden and the writer just north of 

Nelson· Reservoir. At the time this glacial 

drift was introduced the :Missouri was probably 

forced out of the Milk River valley and compelled to flow through a narrow valley south 

of the Larb Hills. WJlen the glacial epoch 

was over and the ice sheet had retreated for 

the last time the waters that could collect in 

the o~d channel formed Milk River,· which flows 

in a very meandering course over the old valley 

floor. In addition to the scattered boulders 

there are in the northern part of this region 

accumulations of glacial material. in which the 

topography is suggestive of moraines. There 

are also in the southern part of the region some 

large areas covered by till or boulder clay. 

ALLUVIUM. 

Soil of various ki1:1ds, brought in since the 

glacial epoch, has been deposited along Milk 

River and other streams of the region. On the 

flood plains of Milk River there is usually a 

gumbo soil, derived from the shale of the 

country, which forms a sticky mud when wet. 

The river has brought down a small quantity 

of sand in some places, and where this is 

deposited the soil is more easily cultivated than 

the gumbo. 

Milk River since _the retreat of the ice has 

trenched its flood plain about 10 or 12 feet, 

developing intricate meanders, and back of the 

river there· are oxbow lakes which show the 

extent of the flood plain. 

Big M;uddy Creek, in the .eastern part of the 

region, flows in a valley cut fron1 100 to 300 feet 

below the late Pliocene or early Pleistocene 

bench. Its flood plain is about a mile wide 

and is co:vered with fine silt, which provides 

the material that doubtless suggested the 

:p.ame for the creek and makes it difficult to 

cross on account of the muddy banks. The 

gravel terraces, from 20 to 50 feet above the 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 120 PLATE VI 

A. VIEW SOUTH ACROSS THE MISSOURI VALLEY, VALLEY AND DAWSON COUNTIES, MONT. 

B . GRAVEL PIT AT WOLF POINT, MONT. 

C. LOGLIKE CONCRETION IN FORT UNION FORMATION. 
GEOLOGY OF 'NOR.THEASTER.N MONT AN A. 37 

flood plain, were probably formed by the large 

·river that occupied the Big Muddy Valley and 

received its water and load of.sand and gravel 

directly from the front of the glacier to the 

north, near the end of the glacial epoch.1 

Along Eagle, Beaver, and Whitetail creeks . . ' tributaries of the Big Muddy, there are at many 

places beaver dams, above which are long strips 

of flood plain called beaver-dam· land. 

.The allu:ium along the forks of Poplar 

River consists largely of reworked Flaxville 

gravel, and because of this gravel the streams 

ca~ be ·easily ·forded at nearly all places. 

Rock Creek has a long, narrow canyon so 

precipitous that it was considered to be too 

rough to survey by the surveyors of the Land 

Office. The upper end of this canyon is near 

Barr post office, above which the valley is 

broad and filled with alluvium. 

Frenchman Creek, by far the largest strean1 

entering Milk River from the north, rises far 

to the northwest in Canada and after crossin(J' 

the international boundary flows in a con1~ paratively nar~ow valley which ht,ts probably 

been eroded since· the last glacial advance. 

The flood plain along it is in general narrower 

than the flood plains of most of the other 

streams. 

White~vater Creek, farther west than Frenchulan Creek, was probably situated in about its 

present com·se before the advance of the lar(J'e 

Wisconsin glacier. Its valley is at least a mile 

wide. and is filled by an extensive glacial 

n1ormne. Cottonwood Creek in its lower part 

has a compm:atively narrow flood plain; the 

upper part of Its com"Se is called Woody Island 

Coulee. The water in this coulee apparently 

at one tin1e flowed eastward and entered the 

valley of Whitewater Creek, but its.old channel 

was blocked with glacial drift, and only one or 

two lakes are left to indicate its former position. 

Beaver Creek, which ente1'S Milk River from 

the so.uth, occupies a broad valley bedded with 

silt, n1aking the stream difficult to ford. The 

lower part of this valley coincides with that of 

the Musselshell, which before the advance of 

· the Wisconsin glacier flowed into the Missouri 

in the valley of Milk River-. The upper part 

of the valley of Beaver Creek from T. 27 N., 

R. 30 ~.,to t~e Coburn ranch, in T. 25 N., R. 

26 E., IS largely filled with glacial till, in which 

the creek is at places intrenched about 20 feet. 

In preglacial time it probably reached the old 

channel of the ~1issouri by way of Alkali Creek. 

For about 12 miles from T. 27 N., R. 30 E., to 

T. 26 N., R. 32 E., Beaver Creek occupies a 

narrow valley cut in the Bearpaw shale. 

Larb Creek, east of Beaver Creek, occupies a 

very broad valley, and its bed is cut in alluvium. There is an easy pass from its head 

over the divide to the present course of the 

Missouri, as there is also from Beaver Creek. 

SOIL OF THE UPLANDS. 

The soil on the plateau surfaces of the re(J'ion 

varies with the char~cter of the underl;ing 

rock. The most interesting soil is that which 

caps the Flaxville gravel. '.(his soil is from a few 

inches to several feet thick and has a sli(J'htly 

dark .col.or. It is. bound together by ~rass roots In Its upper part and contains the bones 

of the bis?n. With the exception of that on 

the Boundary Plateau, this soil does not appear 

to contain much glacial material. South of 

Glasgow there is an extensive upland surface 

beneath which lies the Bearpaw: shale,· but 

~ere there is a sandy soil which owes ~ts origin 

In part to the advance of the ice. Over much 

·of the western part.of the area there is a (J'umbo 

soil derived directly from the Bearpa; shale 

which it overlies. The soil on the Larb flills is 

sandy, being derived from 'the disinte(J'ration b 

of the Lance formation underlying it, mixed 

with a small amount of glacial material. The 

soil overlying the Judith River formation is 

sandy and not quite so good as that which 

overlies the Fort Union and Lance formations. 

In .the parts of the region covered by glacial 

moraines many small lakes have been filled 

since the retreat of the ice. The filling is gen~ 

~rally·grass and other plants that have grown 

In the water, together with materials that have 

blown from the sides. These old lake beds are 

in many places used for farm lands. In the 

large moraine-covered area, which has its center around Whitewater Creek a great many of 

these lakes are still unfilled, and water persists 

in them throughout the average summer. 

STRUCTURE. 

The Bowdoin dome/ northeast of Malta, in 

the. western part of the region, is the most 

obviOus structural feature, and from it the 

I Hoso, nruco, Wood M:ountain-Willowbnnchcoalarea, Saskatchewan: 2 c lli Canada Gool. Survey Mom. 89, p. 50, 1916. 0 er, A. J., The Bowdoin dome, Montana, a possible reservoir of 

oil or gas: U.S. Gaol. Survey Bull. 661, pp. 193-209, 1917 (Bull. 661-E). 
38 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

strata dip away in all directions. The dips are 

usually less than 1°, and where they have been 

determined by careful instrumental surveys 

they are best recorded in feet to the mile. The 

Little Rocky Mountains, about 40 miles southeast of the Bowdoin dome, present an abrupt 

uplift of the strata accompanied by an intrusion of igneous rocks,· forming a laccolith, but 

this disturbance does not extend far from the 

base of the mountain. The beds around this 

uplift are tilted at angles in some places as high 

as 70°. The relation of the Bowdoin dome to 

the structure prevalent in the Little Rocky 

Mountai:q.s is shown in figure 6. 

In the area immediately .surrounding the 

Bowdoin dome the field work has not been in 

sufficient detail to ascertain whether or not 

there are minor structural features, but such 

features are known to exist in the eastern part 

of the region. The Poplar don1e, on Missouri 

River, described by Smith/ is evide!ltly such a 

SE. 

ing a maximum width of about 2 miles is present. In the valley of Big Muddy Creek similar variations .occur in the strike and dip. 

Such features probably are present in the western part of the region but they are very difficult to find because most of the rocks exposed 

are shale, in which it is practically impossible 

to trace individual beds for any distance. 

Two small faults having a displacement of 

less than 15 feet each may be seen on the north 

side of Coal Creek in T. 37 N., R. 45 E., and a 

third fault of similar proportions displaces one 

of the lignite beds near the northwest corner 

of T. 36 N., R. 52 E. No other faults are 

known in either the eastern or the western part 

of the area of flat-lying beds, though they may 

be present. ~In the escarpments of the Flaxville plateau and the late Pliocene or early 

Pleistocene bench large blocks of strata may 

break away fron1 their natural position and 

slump, giving the appearance of a condition 

Bowdoin Dome NW. 

Froun.E 6.-Relations of the Bowdoin dome to the structure prevalent in the Little Rocky Mountains, Mont. a, Madison limestone; b, Ellis 

formation; c, Kootenai(?) formation; d, Colorado group; e, Eagle(?) sandstone;/, Claggett shale; g, Judith River formation; h, Betirpaw shale. 

feature, as it brings up a large elliptical area of which might result froJ;n faulting. This has 

Bearpaw shale nearly surrounded by the Lance occurred at many places in the Judith River 

formation. The formations in1mediately con- formation around the Bowdoin dome. Faults 

cerned dip away from it in all directions. The of great displacement were seen in the Little 

lignite beds along the river east of Brockton dip Rocky :Mountains and in the writer's opinion 

eastward at about 100 to 135 feet to the mile. are common there, but they can not be deIn directions other than east of the dome, scribed without further work in the field. 

where its presence only intensifies the general A word should be said in regard to the struc-

.dip, its effect does not reach farther than 15 ture of the Larb Hills. Calhoun 2 makes the 

miles away and probably the dips are much statement that these hills represent a dome 

lower than those to the east. Similar small whose character is similar to that of the Little 

undulations of the strata can be inferred from Rocky Mountains but which is not eroded sufthe distribution of the Lance and Fort Union ficiently to expose the underlying rocks. This 

outcrops north of the Poplar dome, and several statement is incorrect, for the Larb Hills are 

such features, which are not readily detected, simply an outlier of the large area of Lance and 

were found in the course of mapping the lig- Fort Union rocks exposed south of Missouri 

nite beds. River, and the strata here have a uniformly 

In the vicinity of Scobey, where the general .low dip to the south. It is assumed, theredip. of .the rocks is toward the east, there is a fore, that Calhoun did not make a personal 

westward dip for about a mile. Northeast of examination of these hills but relied on infor~ 

Scobey, south of Coal Creek, a small dome hav-: mation obtained from so·me ot~er source. 

t Smith, C. D., The Fort Peck Indian Reservation lignite field, Mont., 

U. S. Geol. Survey Bull. '381, p. 44, 1910. 

2 Calhoun, F. H. H., op. cit., p. 12. 
GEOLOGY OF NOR.THEASTERN MONTANA. 39 

The major part of the present structure in into it by way of the lower portion of the 

both the large flat-lying portions of the forma- Beaver Creek valley. By this change about 

tion.':> and the highly upturned portions in the 70 miles of the lower part of Musselshell River 

Littl~ Rocky Mountains was introduced sub-. was· diverted. Larb Creek was probably a 

sequent to the deposition of the Fort Union much larger stream heading south of the 

formation and before that of the Oligocene Missouri and passing through the Larb Hills 

gravel in the Cypress Hills, for this gravel rests by way of 'the Timber Creek valley. The 

unconformably upon the eroded surfaces of glacier from the north filled the whole of the 

the Fort Union, Lance, and Bearpaw forma- Milk River valley and was thick and active 

tions indiscriminately. In other words, this enough to cover the Larb Hills with glacial 

·revolution occurred in late Eocene time. drift. At its front the great volume of water 

That a 1ninor part of the folding may have due to melting ice and an attendant moist 

been accomplished since the deposition of the climate easily eroded a new channel in the 

Fla.."\:ville gravel is indicated by the fact that soft Lance formation and Bearpaw shale. A 

·some of the streams in the eastern part of the view south across the gorge of the Missour.l, 

region occupy synclinal valleys and by the ab- 700 to 800 feet in depth, is shown in Plate 

·sence of the· Flaxville gravel between Opheim VI, A. 

and the Boundary Plateau, it being assumed An old channel of the Missouri from Cuithat an uplifted portion of the plateau would bertson to Lakeside, which is followed by the 

be n1ore subject to erosion than the lower- Great Northern Railway, and a broad depreslying part. sion extending from the Big Muddy Valley 

ADJUSTMENTS OF DRAINAGE. 

:Most stream adjustments in northeastern 

Montana are due to the invasion of ice during 

the glacial epoch. One of the most obvious 

features of this kind can b~ seen on Wolf 

Creek, a tributary of the Big Muddy, for its 

headwaters have been diverted and captured 

by the South Fork of Eagle Creek, largely 

because of glacial drift piled across its valley 

in tsecs. 8 and 9, T. 34 N., R. 51 E. Reference 

has been made to the change in the course of 

Woody Island Coulee, in T. 36 N., R. 28 E., by 

the filling up of its valley with glacial drift 

and to a possible old cour.se of the headwaters 

of Beaver Creek by way of Alkali Creek to 

:Mille River, a short distance abo~e Malta. 

The most pronounced stream adjustment 

in this region, however, is the diversion of 

:Missouri River fron1 the Milk River valley, 

which Calhoun 1 has described. The present 

valley of the Missouri south of the Larb Hills 

is practically a canyon 800 feet deep and not 

more than 2 miles across from rim to rim, 

whereas its old valley, now occupied by Milk 

River, is much broader and shallower. Before 

the river was diverted :Musselshell River flowed 

1 Calhoun, li'. H. H., op. cit., pp. 34-45. 

at Medicine Lake northwestward, crossing the 

State boundary about 6 miles south of the 

Canada line, have been described by Beekly.2 

The course of the depression is marked by a 

chain of shallow intermittent lakes. Bauer 3 

has assumed that this feature also is an old 

channel of the :Missouri, in which it flowed 

northward to I-Iudson Bay by way of Souris 

and Assinniboine rivers before the glacial 

epoch. The south end of this depression 

near Poplar has recently· been inspected by 

Alden, who states 4 that its floor is about 200 

feet above that of the present valley of the 

Missouri, and that its topography blends 

with the long slopes which characterize the 

early Pleistocene or late Pliocene bench of this 

region. Alden suggests that the river prob&bly 

occupied this valley as long ago as the Pliocene epoch and that it was diverted at the 

time of the first invasion of ice early in the 

Pleistocene. The late Pliocene or early Pleis-· 

tocene gravel described on pages 35-36 was 

probably laid down in or near the channel of 

one of the streams which contributed to form 

this river. 

2 Beekly, A. L., Tho Culbertson lignite fteld, Mont.: U.S. Geol. Survey 

Bull. 471, pp. 320-.123, 1912. 

s Bauer, C. M., A sketch of the late Tertiary history of the upper Mi&· 

souri River: Jour. Geology, vol. 23, pp. 52-58, 1915. 

• Alden, W. C., oral communication . 

• 
• 
DEPOSITS OF CLAIBORNE AND JACKSON AGE IN GEORGIA. 

By CHARLES WYTHE CooKE and I-IAROLD KuRTZ SHEARER. 

INTRODVCTION. 

In 1911 the Goo logical · Survey of Georgia 

·published as Bulletin 26 a "Prelimina~·y 

repo-rt on the geology of the Coastal Plain. of 

Georgia," by Otto Veatch and Lloyd William 

Stephenson, prepared in cooperation with the 

United States Geological Survey under the 

&Upervision of T. Wayland Vaughan, geologist 

in charge of Coastal Plain investigations, who 

contributed the determinations of the invertebrate fossils of the Tertiary and Quaternary 

formations. Although this report constituted· 

a decided advance in our knowledge of the 

geology of the Coastal Plain o.f Georgia, it 

was admittedly of reconnaissance character, 

and corrections and additions to it were to be 

0.."\:pected. During the last few years field work 

has been prosecuted .vigorously in the Coastal 

Plain of Georgia, and the additional information thus accumulated throws light upon 

certain problems of stratigraphy left unsolved 

by Veatch and Stephenson and alters considerably son1e of their correlations. The 

<>bject of the present paper is to present the 

new evidence regarding the age and correlation 

of the Eocene formations of Georgia and to 

revise in accordance with present knowledge 

the descriptions of the deposits of Claiborne 

and Jackson age. 

SUMMARY OF EOCENE AND LOWER OLIGOCENE 

FORMATIONS AS KNOWN TO 1911. 

The chapters on the Eocene and lower Olig-

·Ocene fonnations in the Coastal Plain report 

will be briefly summarized. · Veatch and Stephenson recognized the following formations: 

Lower Oligocene: 

Vicksburg formation. 

Eocene: 

Jackson formation. 

Claiborne group. 

Barnwell sand. 

McBean formation. 

Congaree clay member (at base). 

Wilcox formation. 

.Midway formation. 

The Midway and Wilcox formations are 

confined to the region west of Perry, I-Iouston 

County. East of Perry both formations are 

overlapped by younger strata. 

The McBean formation of Veatch and 

Stephenson consists mainly of clays in the 

nature of fuller's earth, of marls, sandy limestones, and calcareous glauconitic sands. An 

extensive . marine fauna containing many 

characteristic lower (Jlaiborne mollusks occurs 

in the marls on McBean Creek,··Burke County, 

and also in the lower part of Shell Bluff on 

Savannah River. A series of fuller's earth 

grading into calcareous clay which is exposed 

at short intervals from Grovetown, Columbia 

County, southwestward along the Fall Line 

to Bibb and Twiggs counties~ was correlated 

on lithologic grounds with Sloan's Congaree 

"phase" of the South Carolina Eocene and 

designated the "Congaree clay rnember of the 

McBean formation." 

The Barnwell sand, correlated with Sloa\1's 

Barnwell "phase" in South Carolina, consists 

largely of unconsolidated red and varicolored 

sands, with some indurated beds of gray sandstone and lumps of silicified limestone or flint. 

They stated that it overlies directly the McBean 

fo'rmation and is in contact with both the 

'marls and the "Congaree" clay member of 

that formation, but the nature of the contact 

had not been satisfactorily determined. In 

places the Barnwell overlaps the McBean 

formation and rests directly upon the Lower 

Cretaceous: It carries a; marine fauna which 

contains a number of species in common with 

the Gosport sand of Alabama (upper Chiiborne) and was correlated with that formation. 

The Jackson form~;ttion as originally mapped 

by Veatch and Stephenson included a smalL 

patch on Chattahoochee River, a small outlier on the Cretaceous at Rich I-Iill, Crawford 

County, and a long, narrow area-running fr01n 

a point about 8 miles southwest of Sandersville to a point 6 miles east of Montezuma. On 

41 
42 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

the map accompanying the report on the 

ground waters of the Coastal Plain of Georgia 

by the same authors 1 this area was extended 

into southwestern Sumter County. 

The Vicksburg format!on of Veatch and 

Stephenson included besides strata of true 

Vicksburg. age the great mass of limestone 

underlying the lower drainage basin qf Flint. 

and Chattahoochee rivers and forming the 

northern extension of the Ocala limestone of 

Florida. · 

RECENT INVESTIGATIONS AND THE INCEPTION 

OF THE PRESENT WORK. 

The recent discovery that the Ocala. limestone is of Jackson age 2 has largely increased 

the known areal extent of the deposits of that 

age, at the expeuse of the Vicksburg formation. 

The area of deposits of Jackson age has been 

further extended by Brantly,3 to include most 

of those parts of Wilkinson and Twiggs counties formerly mapped as Claiborne. Brantly 

also expressed the o}:>inion that the "Congaree" 

clay of previous reports seems to be the continuation of the Jackson limestone and fuller's 

earth of I-Iouston County.4 The same opinion 

concerning the stratigraphic relations of the 

'' Congaree '' clay was reached by H. K. Shearer, 

assistant State geologist, in the course of field 

investigations of the fuller's earth deposits of 

Georgia,5 but as the published correlation of 

the ''Congaree" clay with the Claibqrne group 

seemed to be supported by as good paleontologic evidence ~ts the correlation of the limestone with the Jackson, he was uncertain to 

which epoch the fuller's earth deposits properly belong. 

At the request of Prof. S. W. McCallie, State 

geologist of Georgia, C. Wythe Cooke was assigned by the United States Geological Survey 

to accompany Mr. Shearer over the field, with 

the object of reconciling the discrepancies between the apparent stratigraphic relations of 

the deposits in eastern and central Georgia as 

determined by Mess:rS. Brantly and Shearer and 

1 U.S. Geol: Survey Water-Supply Paper 341, pl. 3, 1915. 

2 Cooke, C. W., The age of the Ocala limestone: U. S. Geol. Survey 

Prof. Paper 95, pp .. 107-117, 1915. 

3 Brantly, J. E., Report on the limestones and marls of the Coastal 

Plain of Georgia: Georgia Geol. Survey Bull. 21, 1916. 

4 Idem, p. 8. 

6 Since the completion of this manuscript Shearer's report on the 

bauxite and fuller-'s earth of the Coastal Plain of Georgia has been pub~ 

lished as Bulletin 31 of the Georgia Geological Survey. He has adopted 

the correlations proposed here. 

the ages indicated by previously published lists 

of fossils. 

Field work was done by the writers jointly 

from March 20 to April 19, 1919, and during 

that time all the n1ost significant known exposures of Eocene strata in the region between 

Flint and Savannah rivers were visited and 

collections of fossils were n1ade wherever 

possible. 

The succeeding fortnight was spent by :Mr. 

Cooke in visiting the type localities of the South 

Carolinian Eocene for the purpose of deternlining the propriety of applying the names Congaree and Barnwell to geologic formations in 

Georgia. Mr. Shearer subsequently exan1ined 

the Claiborne deposits in Georgia west of Flint 

River. The results of :Mr. Cooke's previous 

(1914) studies of the Ocala limestone are also 

incorporated in this paper. 

The writers are indebted to Prof. E. W. 

Berry, of Johns Hopkins University, and to 

Dr. R. S. Bassler, of the National Museum, for 

reports on the plant remains and Bryozoa, 

respectively, and to Dr. Joseph A. Cushman 

for identifications of the Foraminifera. The 

other fossils collected in the course of this 

investigation have been identified by Mr. 

Cooke, who has also had the privilege of examining the collections in the National Museum 

upon which were based the correlations published in the preliri::tinary report on the geology 

of the Coastal Plain of Georgia. The present 

paper was prepared under the direction of T. 

Wayland Vaughan, geologist in charge of 

Coastal Plain investigations of the United 

States Geological Survey, who has given it 

continuous personal attention and has made 

a number of suggestions that have been adopted 

by the writers. 

CRITICAL SECTIONS AND EOCENE FAUNAS OF 

EASTERN GEORGIA. 

DRY BRANCH. 

In the vicinity of Dry Branch, Twiggs 

County, are good exposures of Eocene beds 

which were referred to the Claiborne group by 

Veatch and Stephenson,. on the basis of 

Vaughan's identific~tions of the fossils, but 

which later discoveries have shown to be of 

Jackson age. The following section is typical. 

The formation names used are those adopted in 

this report. 
{j 

DEPOSITS OF CLAIBORNE AND JACKSON AGE IN GEORGIA. 43 

Section at the mines of the Georg·ia Kaolin Co., 2 miles east 

of Dry Branch. 

Vicksburg or Barnwell formation: Feet. 

7. Red sand, capping hill, about. . . . . . . . . . . 80 

Barnwell formation (Twiggs clay member): 

6. Greenish-gray fuller's earth (buff when ~ 

. dry) .................................. 30-40± 

Ocala limestone (Tivola tongue): 

5. Impure white argillaceous limestone, 

grading into fuller's earth. Pinches 

out toward the north and northwest and 

is absent in the northwestern part of the 

quarry. Contains many Bryozoa. Separated from the underlying bed by a 

somewhat irregular contact............ 0- 5 

Barnwell formation (lower part): 

4. Yellow sand with black carbonaceous 

stains. Contains a few large bones of. 

Basilosaurus cetoides (Owen) 1 ••••••••••• 1- 2! 

3. Yellow to red sand, medium coarse, irregularly bedded........................ 12 

2. Gray sandstone with calcareous cement, 

loaded with casts of mollusks. Pinches 

out at north end of quarry, where the 

kaolin is overlain by glauconitic sand.. 0- ~ 

Unconformity. 

Lower Cretaceous: 

1. White kaolin. . .. .. . . . . . .. . . . . .. . . . . . . . . 15-20 

The fossils collected from the basal Eocene 

at this locality are listed below. 

Station 7691. Pit of Georgia Kaolin Co., 2 miles east of 

Dry Branch, Ga. Bed 2 of section. Basal sandstone 

immediately ovedying the Lower Cretaceous. Cooke 

and Shearer, collectors, 1916. 

Levifusus trabeatus (Conrad)? 

Levifusus sp. · 

Ficus filius (Meyer). 

Turritella sp. 

Mesalia vetusta (Conrad). 

Calyptraea sp. 

N ucula magnifica Conrad. 

Leda cf. L. mater Meyer. 

Leda cf. L. plicata (Lea). 

Leda·regina-jacksonis Harris? 

Glycymeris staminea (Conrad)? 

Glycymeris sp. 

Barbatia cuculloides (Conrad). 

Ostrea trigonalis Conrad. 

Ostrea sp. 

Pteria limula (Conrad)? 

Panope porrectoides (Aldrich). 

Corbula oniscus Conrad var. 

Corbula densata Comad. 

Phacoides (Miltha) pandatus (Conrad). 

Phacoides alveatus (Conrad) var. 

Phacoides (Here) sp. 

Tellina, 2 sp. 

Macoma sp. 

Metis sp. 

Tagelus sp. 

Meretrix securiformis (Conrad)? 

Protocardia nicolleti (Conrad). 

1 Identified by C. W. Gilmore. 

Many of the mollusks in this list occur in 

both Claiborne and Jackson deposits, but 

Ficus filius, Leda mater, Leda regina-jacksonis, 

Ostrea trigonalis, Meretri:-c securiformis, and 

Protocardia nicolleti are particularly characteristic of the Jackson and are rare or unknown 

in older beds. M esalia vetusta, which had been 

previously thought to be confined to the upper 

Claiborne (Gosport greensand horizon), has 

recently been found at the base of the Jackson 

formation at Sims, Yazoo County, Miss. 

Basilosaurus cetoides, the zeuglodon, which 

occurs in bed 4, is so far 'as known confined to 

the Jackson, and in most places is most abundant near the top. 

According to R. S. Bassler, the Bryozoa in 

bed 5 constitute a fauna peculiar to the middle 

Jackson. The same fauna occurs at Rich Hill, 

Crawford County, and numerous other loculities in central Georgia and will be referred to 

for convenience as the Rich I-Iill facies of the 

Jackson fauna. 

The fuller's earth of bed 6, a greenish hacldy 

clay of low specific gravity, resembles the beds 

exposed at numerous localities in central and 

eastern Georgia and referred by Veatch and 

Stephenson to the "Congaree" clay member 

of the McBean formation. 

The red sand at the top of the section was 

correlated by Veatch and Stephenson with 

·the Barnwell sand, and the und~rlying beds 

:were placed doubtfully with the McBean formation.2 

Certain problems in stratigraphy, which the 

authors cited were unable to explain under 

the supposition that the strata near Dry 

Branch ·are of Claiborne age, vanish immediately when it is discovered that the deposits 

are of Jackson age. For instance, they say: 5 

According to Dr. Vaughan the evidence of the fossils 

shows that Jackson strata occur near the mines of the 

Georgia Kaolin Co., 2 miles southeast of Dry Branch. 

There is an exposure of 15 feet of soft white argillaceous 

marl in a small ravine one-half mile southeast of the clayworking plant, which contains Bryozoa and other fossils 

and is similar lithologically to the marl at Rich Hill. It 

lies 10 to 15 feet above the white clay beds of the Cretaceous and is overlain by 125 feet of bluish or drab lami-

.nated sandy clay and red sand, the clay containing thin 

slabs of quartzite or sandstone. In this vicinity Claiborne 

fossiliferous strata occur at both higher and lower levels 

than this marl, and' the presence of J~t:ckson beds in tlus 

.2 Veatch, Otto, and Stephenson, L. W., Geology ·or the Coastal Plain 

or Georgia: Georgia Geol. Survey Bull. 26, p. 256, 1911. 

a Idem, p. 304. 
44 SHORTER CONTRlBUTIONS TO GENERAL' GEOLOGY, 1918. 

position implies either a deep erosion unconformity between the two formations or a flexure. Exposures in this 

vicinity, so far as they have been examined, afforded no 

evidence of an unconformity or of any faulting or folding 

of the beds. Further detailed field work is necessary to 

solve tlris problem 'Of stratigraphy. 

The problem has been solved by the discovery that the beds higher and lower than 

the marl are Jackson and not Claiborne. 

SOUTH OF PERRY. 

Other localities which presented difficulties 

to Veatch and Stephenson are Mossy Hill and 

Ross Hill, in Houston County. These hills 

are a few miles apart qn the escarpment south 

of Mill and Flat creeks, which extends northeastward, approximately parallel to the general strike of the formations of the Coastal 

Plain in this part of the State. Ross I-Iill is 

crossed on the road from Perry to Elko, 3 

miles south of Perry, and Mossy HilJ lies on the 

National Highway (the road from Perry to 

Henderson) about 5.7 miles southwest of Perry. 

The entire section at .Ross Hill, with the 

exception of 10 feet at the top, was referred by 

Veatch and Stephenson to the Jackson formation, and this correlation was supported by 

lists of fossils identified by Vaughan. The 

following section measured by the writers is 

in essential agreement with that of Veatch and 

Stephenson.1 The base of the section is 2·5 

feet above Mill Creek. 

Section on Perry-Elko road at Ross Hill. 

Oligocene (?): Feet. 

Vicksburg formation (?): 

7. Concealed to edge of plowed field on top 

of hill, which rises a few feet higher.· 

The surface is st.rewn with lumps of 

sparingly fossiliferous chert .......... 15 

Eocene (all of Jackson age) : 

Barnwell formation: 

6. Soft cream-colored to yellow sandy limestone with casts of fossils. Lunularia 

distans, Endopachys, Calyptraea, Leda, 

and Pecten.......................... 4± 

5. Light-colored limestone at base; upper 

part concealed but with debris of soft 

limestone with Periarchus pileus-sinensis and Bryozoa. . . . . . . . . . . . . . . . . . . . . 15 

4. Hackly cream-colored calcareous clay 

(fuller's earth) with lime concretions. 24 

Ocala limestone (Tivola tongue): 

3. Cream-colored limestone, soft when 

fresh, with a hard ledge at bottom. 

Has been quarried in part. · ContainR 

Pecten perplanus and many Bryozoa.. 7~ 

1 Op. cit., p. 301. 

Section on Perry-Elko road at Ross Hill-Continued. 

Eocene (all of Jackson age)-Conti'nued. Feet. 

Ocala limestone (Tivola tongue)-Continued. 

2. Soft greenish-yellow limestone, speckled 

with glauconite and with locally indurated nodules or ledges. Very argillaceous toward the top and contains numerous soft, irregular lime 

concretions. Bryozoa ............... . 

1. Pale cream-colored soft limestone, replete with Bryozoa (Rich Hill fac.:.es 

of Jackson fauna). Hard ledges near 

the top. Contains also Periarchus 

pileus-sinensis. Exposed east of the 

road................................ 38 

The following section was n1easured in a 

gully on Ross Hill about 300 yards west of the 

Perry-Elko road. The top of the hill here is 

probably 40 feet or more higher than at the 

road. The base of the section is by barometer 

40 feet above the bridge over Mill Creek. 

Section on Ross Hill 800 yards west of Perry-Elko road. 

Oligocene (?): 

Vicksburg formation (?): Feet. 

14. Red sand with "buckshot" ferruginous lumps. Fragments of fossiliferous chert on top. . . . . . . . . . . . . . . . . . . . 30 

Eocene: 

Barnwell formation (Twiggs clay member): 

13. Glauconitic clay and fuller's earth, 

poorly exposed..................... 15± 

12. Glauconitic grains in a matrix of yellowish, calcareous clay. Pecten sp., 

etc .... ·............................ 2!± 

11. Gray hackly clay (fuller's earth); upper 

2 feet containing lenses or nodules of 

glauconitic material resembling bed 

12 ...... :. ... .. .. . . .. . . .. . . . ....... 7t± 

10. Lens or nodule of greenish-gray limestone with casts of Corbula, probably 

C. wailesiana........... .. .. .. . . . . . . . . 1 

9. Fuller's earth........................ 4 

8. Limestone.......................... 1 

7. Calcareous fuller's earth. . . . . . . . . . . . . • 15 

6. Continuous ledge of gray limestone 

with poorly preserved mollusks..... ! 

5. Calcareous fuller's earth containing 

soft, white chalk nodules........... 3! 

4. Hard light-gray limestone, softer at 

bottom. Contains some Bryozoa, 

Flabellum, Turritella carinata, Mesalia vetusta, Pecten, Meretrix, and 

Periarchus pileus-sinensis............. 3 

3. HaclrJy cream-colored calcareous clay 

(fuller's earth). The base oftliis bed 

is the same as the base of bed 4 of 

preceding section. . . . . . . . . . . . . . . . . . . 35 

Ocala limestone (Tivola tongue): 

2. Soft argillaceous limestone loaded with 

Bryozoa (Rich Hill facies of Jackson 

fauna). Contains also Ostrea trigonalis and Pecten perplanus. . . . . . . . . 7 

1. Hard and soft ledges of limestone with 

Bryozoa, Pecten perplanits,· and Periarchus pileus-sinensis very abundant. 17 
DEPOSITS OF CLAIBOHNE AND JACKSON AGE IN GEORGIA. 45 

Bed 4 is particularly significant in that it 

shows the presence of Turritella carinata and 

Mesalia vetusta, which were considered by 

Vaughan to be diagnostic upper Claiborne 

fossils, well above the base of the deposits of 

Jackson ·nge. 

The geologic conditions at Mossy Hill appear 

to be similar to those at Ross I-Iill, but the exposures are less con1plete. The following section, exposed in and near an old quarry about 

100 yards east of the National Highway, extends frOin a gully below the quarry to a lev~l 

bench on the road. 

Seclion at Mossy Hill. 

Oligocene, Vicksburg formation: 

13. Red argillaceous sand with chert fragments, 

commencing at a level bench on the 

National Highway and capping the upland area to the south . . . . . . . . .. . .. .. . . . . . 30 

Eocene: Barnwell formation (Twiggs clay member): 

12. Mostly concealed, but interbedded fuller's 

ea1:th and bryozoan limestone are exposed in 

a gully east of the road a few feet below the 

bench .................................. 25 

11. Yellow to green, partly indurated glauconitic 

marl..................................... 5 

10. Calcareous clay 1·esembling fuller's earth, with 

a locally indurated stratum at top......... 5! 

9. Impure yellowish limestone with casts of 

fossils................................... 2; 

8. Concealed................................ 6 

7. Clay or fuller's earth with chalk concretions.. 2 

6. Concealed ................................ 14 

5. Calcareous fuller's earth, exposed on roadside.................................... 3 

4. Hard limestone............................ ; 

3. Calcareous fuller's earth.................... 2; 

2 Argillaceous fossiliferous limestone with hard 

ledges; quarried. . . . . . . . . .. . .. . . . . . . . . . .. . 11 

1. Gray calcareous clay with lime nodules below, 

grading upward into fuller's earth with lime 

nodules; exposed in gully below quarry.,. 21 

·The stratum immediately below the bed 

from which these species were oollected contains Bryozoa which R. S. Bassler refers to 

the horizon of the deposits of Jackson age at 

Baldock, S. C. The stratum in the quarry 

from which the fossils were collected seems 

to be identical with bed 4 of the section on 

Ross Hill west of the Perry-Elko road. Not 

only are the species, so far as they oan be 

identified, the same, but the rooks in which 

they are embedded look alike, and the sections both above and below the fossiliferous . 

zone are similar. Moreover, the topographic 

relations of the two localities are such as to 

indicate that the beds at both are at ·the same 

horizon, provided, of course, that there are 

no structural disturbances, of which there is 

no evidence. 

In the Coastal Plain reportt the lower part 

of the section at Mossy Hill was referred to the 

Claiborne group on the basis of collections of 

fossils made by T. W. Vaughan and· S. W. 

McCallie. The species collected by Vaughan 

at Mossy Hill are listed as follows: 

Flabellum cuneiforme Lonsdale. 

Turbinolia pharetra Lea. 

Endopachys maclurii (Lea). 

*Turritella carinata Lea. 

*Mesalia vetusta (Conrad). 

Calyptraea aperta (Solander). 

Dentalium thalloides Conrad. 

Nucula ovula Lea. 

Leda sp. 

Leda sp. 

Glycymeris idoneus (Conrad)? 

*Phacoides alveatus (Conrad). 

Venericardia, 2 or 3 sp. 

Cytherea sp. 

Crassatellites sp. 

Corbula oniscus Conrad or wailesiana Harris. 

Corbula densata Conrad? 

From bed 2 the following species were Geologic horizon, Claiborne. Species marked * are 

obtained: not known from the Jackson. 

Station 7682. Quarry on Mossy Hill. Cooke and Shearer, 

ollectors, f916: 

Endopachys sp. 

Lu.nularia distans (Lonsdale). 

Turritellacarinata Lea. 

Mesalia vetusta (Conrad). 

Leda cf. L. plicata (Lea). 

G 1 ycymeris sp. 

Pecten perplanus Morton. 

Phacoides alveatus (Conrad). 

~:filtha claibor:nensis (Conrad). 

Dentalium sp. 

28288°-19-4 

It will be noted that the only species ohecked 

tts not known fron1 the Jackson are Turritella 

carinata, M.esalia vetusta, and Phacoides alveatus. The first and second have since been 

found in the beds of Jackson age at Ross Hili, 

and th~ second and ·third at the mine of the 

Georgia Kaolin Co. One of the undetermined species of Leila listed occurs also at the 

latter place. 

1 Veatch, Otto, and Stephenson, L. W., op. cit., pp. 258-260. 
46 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

The fossils collected by McCallie are listed 

as follows: 

Turbinolia pharetra Lea. 

Flabellum cuneiforme Lonsdale. 

Plej on a petrosa (Conrad). 

*Turritella carinata Lea. 

Mesalia vetusta (Conrad). · 

Dentalium thalloides Conrad; 

Nucula ovula Lea. 

Leda. 

*Glycymeris trigonella (Conrad). 

Pteria sp. 

*Phacoides alveatus (Conrad). 

*Phacoides aff. P. claibornensis (Conrad). 

Venericardia planicosta Lamarck. 

*Venericardia·alticostata (Conrad). 

Cytherea sp. 

*Crassatellites protextus (Conrad). 

*Corbula oniscus Conrad. 

*Pteropsis lapidosa (Conrad). 

Species marked * are not known from beds above 

the Claiborne. Pteropsis lapidosa is characteristic of the 

lower Claiborne. 

This does indeed look like a Claiborne fauna, 

and with the data then available Vaughan was 

perfectly justified in referring these fossils to 

the Claiborne group; but, as we shall see later, 

nearly all the species checked have since been 

found associated with Jackson fossils. The 

exception to these is P~eropsis lapidosa, which 

elsewhere seems to be confined to the lower 

Claiborne. As this collection of fossils apparently is not now in the National Museum, the 

identifications of the species could not be 

checked nor could the matrix be examined to 

ascertain whether there had been accidental 

mixture of specimens from different localitie!:?. 

There is some uncertainty as to the locality 

at which the fossils ascribed to Mossy Hill were 

obtained. According to Veatch and Stephenson/ Mossy Hill is on the Perry-Elko road 4! 

miles south of Perry, a location corresponding 

nearly with that of Ross Hill. However, as 

there seems to be little doubt that the horizon 

is the same as that from which the writers obtained Turritella carinata and Mesalia vetusta, 

the exact locality is of no particular importance. 

VICINITY OF GIBSON. 

A collection made by the writers from sandstone ledges exposed on the hillside east of 

Rocky Comfort Creek, on the Brassell property, 2 miles northeast of Gibson, Glascock 

1 Op. cit., p. 258. 

County, shows the presence in Georgia of a 

fauna not previously recognized east of Arkansas. The fossils are preserved in the fonn of 

hollow molds or siliceous pseudomorphs, some 

of which ha:ve weathered out of the sandy 

matrix. The rock, which is an indurated 

facies of the: basal sand bed of the Eocene that 

is of widespread distribution in this part of the 

State, is exposed to a thickness of 3 or 4 feet 

but probably extends somewhat deeper. It 

lies not far above the Cretaceous, but the con-

'Otact is not exposed here. The fossils collected 

are enumerated in the accompanying list, in 

which the initials C and J signify that the 

species so marked occur elsewhere in Claiborne 

and Jackson deposits, respectively. 

Station 7710. Brassell property, 2 miles northeast of 

Gibson, Glascock County. Cooke and Shearer collec-: 

tors, 1916. 

OJ Flabellum cuneiforme Lonsdale. 

J Astrhelia burnsi Vaughan? 

OJ Cancellaria gemmata Conrad. 

Olivella sp. 

OJ Margin ella semen Lea? 

' Psilocochlis mccalliei (Dall). 

OJ Lapparia pactilis (Conrad). 

OJ Plejona petrosa (Conrad). 

J Levifusue branneri Harris. 

OJ Levifusus trabea.tus (Conrad). 

OJ Mazzalina inaurata (Conrad) var. 

Fueinue aff. F. bellus (Conrad). 

J Murex marksi Harris. 

OJ Peeudoliva vetusta (Conrad). 

OJ Calyptraphorus velatus (Conrad). 

Ceri thi urn sp. 

J Ficus :filius (Meyer). 

OJ Turritella carinata Lea. 

OJ Mesalia vet,Ista (Conrad). 

OJ Natica minima Lea. 

J Natica permunda Conrad? 

Dentalium sp. 

J Leda regina-jacksonis Harris. 

OJ Leda multilineata Conrad? 

OJ Glycymeris staminea (Conrad) 

OJ Pteria limula (Conrad). 

Crenella sp. 

Pecten n. sp. 

CJ Corbula densata Conrad. 

OJ Phacoides (Miltha) claibornensis (Conrad). 

Phacoicles sp. · 

OJ Crassatellites protextuo (Conrad) var. 

Crassatellites n. sp? 

OJ Macrocallista perovata (Conrad)? 

OJ V enericardia planicosta (Lamarck). 

C Venericardia alticostata Conrad var. 

To this list should be added the following, 

which were obtained with other fossils from 

the same horizon at station 7711, on the east 
DEPOSITS OF CLAIBORNE AND ;r ACKSON AGE IN GEORGIA. 47 

side of Deep Creek, 3-?f miles northeast of Gibson 

and about It miles from the Brassell locality: 

J Turritella clevelandia Harris. 

Leda plicata (Lea) var. 

Trinacria? sp. 

J Corbula wailesiana Dan.· 

The section there is as follows: 

Section on roadside east of Deep Creek, 9! miles northeast of 

Gibson. 

Eocene (Barnwell formation): Feet. 

7. Mottled red or orange-colored sand. . . . . . . . . . . 50± 

6. Fuller's earth with sand laminae ........... 11 

5. Unconsolidated sand similar to No.4....... 5 

4. White or gray fossilifero"us sandstone like that 

on Brassell property. . . . . . . . . . . . . . . . . . . . . . 6 

3. Gray clayey sand........................... 4 

2. Concealed ................................ 10 

Cretaceous: 

1. Kaolin and white sand ...................... 15 

This fauna, which occurs within 15 feet of 

the Eocene-Cretaceous unconformity, bears a 

remarkably close resemblance to that occurring 

at White Bluff and Crowleys Ridge, Ark., 

which was formerly referred to the Claiborne 

group but is now correlated with the lower 

Jackson. 1 It is rather surprising to encounter 

such species as Levifusus branneri, Murex 

marlcsi, and Turritella clevelandia, which are 

typical of the Jackson deposits in Arkansas, 

so far east of their previously known r.ange; 

but their presence, as well as the general aspect 

of the fauna, is good evidence that the beds 

containing them occupy approximately the 

same stratigraphic position. The presence of 

Astrhelia burnsi, Ficus filius, Natica permunda, 

Leda r·egina-jaclcsonis, and Oorbula wailesiana 

affords strong additional evidence that the 

deposits are of Jackson age. 

It will be noted that this list, which is much 

more comprehensive than any previously compiled from this region, contains nearly all the 

species that were considered by Vaughan to be 

diagnostic of the upper Claiborne. There are, 

in addition, a few species that are abundant 

at this horizon in Georgia but have not yet 

been found elsewhere. Among these may be 

mentioned Psilocochlis mccalliei and an undescribed species of Pecten which has hitherto 

been confused with Pecten wilcoxii and P. 

wahtubbeanus. 

Fossils representing this same horizon and 

embedded in a similar matrix of gray sandstone 

t Stophonson, L. ·w., and Crider, A. F., Geology and ground waters 

or northeastern Arkansas: U. S. Geol. Survey Water-Supply Paper 399, 

pp. 73-84, 1916. 

which were collected by McCallie on the English plantation, 1 t miles north of Gibson, were 

referred by Veatch and Stephenson 2 to the 

McBean formation. The revised list follows: 

Station 3943. English plantation, 1! miles north of 

Gibson. S. W. McCallie, collector, 1904. 

Flabellum cuneiforme Lonsdale. 

Endopachys maclurii (Lea). 

Mazzalina inaurata (Conrad). 

Plejona petrosa (Conrad). 

Turritella clevelandia Harris. 

Turri tell a sp. 

Pecten n. sp. 

Pteria limula (Conrad)? 

Panopesp. . 

Phacoides (Miltha) claibornensis (Conrad). 

Venericarclia alticostata Conrad var. 

The same fauna has. been recognized at 

several·localities between Glascock and Bibb 

counties and is usually found in more or less 

indurated gray sandstone resembling that near 

Gibson. All these exposures were referred 

by Veatch and Stephenson to the Claiborne 

group,..-some to the McBean formation, others 

to the Barnwell sand. 

BROWNS MOUNTAIN AND VICINITY. 

At Browns Mountain, Bibb County, 9 miles 

southeast of Macon, the strata were referred to 

the Barnwell sand.3 

At this locality the main exposures consist of 

about 20 feet of hard gray sandstone, part of 

which appears to grade into sandy limestone. 

rt· contains fossils that are locally abundant 

but are not very well preserved. Above the 

sandstone are poor exposures of bryozoan 

limestone with Pecten. perplanus ?. Beneath 

the· sandstone are incomplete ·exposures of 

fuller's earth and sand. 

The relations are more evident on a hill 

on the Marion road, four-tenths of a mile 

southwest of Bond's store, where the following 

section was observed: 

Section on Mar~on road 9 miles southeast of Macon. 

Eocene: Foot. 

6. Hard sandstone and q~tartzite, to top of hilL.. 7 

5. Mottled plastic clay... . . . . . . . . . . . . . . . . . . . . . . 3 

4. Red sand..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 

3. Soft fossiliferous sandstone .................... 0-4 

2. Basal conglomerate; white kaolin pebbles in 

cross-bedded sand. Contact with Cretaceous 

not precisely located because of lithologic 

similarity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 

Cretaceous: 

1. Coarse white kaolinic sanu to stream leveL . . . G5 

2 Op. cit., p. 273. a Idem, pp. 25S-260. 
48 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

Stratum 3 of the section consists of a discontinuous ledge of sandstone which in places is 

reduced to lumps embedded in incoherent 

·sand. It contains casts of mollusks, including 

Pecten n. sp. Bed 6 is also unequally indur-

_.ated but is more persistent than bed 3. It 

carries Periarchus pileus-sinensis and other fos-

·sils. Beds 3 to 6 are equivalent to the hard 

rock on Browns Mountain, half a mile away. 

The following lists enumerate the species 

collected in this vicinity: 

Station 7695. Hilltop oil Macon-1V[arion road four-tenths 

of a mile southwest of Bond's store, Bibb County. 

C. Wythe Cooke, collector, 1916. 

Nucula ovula Lea? 

Leda regina-jacksonis Harris? 

Glycymeris-sp. 

Pecten n. sp. 

Cytherea sp. 

Periarchus pileus-sinensis (Ravenel)? 

Station 7696. Browns Mountain, near Bond's~ store, 9 

miles southeast of Macon. C. Wythe Cooke, collector, 

1916. 

Flabellum cuneiforme Lonsdale. 

Lunularia sp. 

Turri tella sp. 

Mesalia vetusta (Conrad). 

Calyptraea sp. 

Nucula spheniopsis Conrad. 

Leda mater Meyer. 

Pecten n. sp. 

Pecten perplanus Morton? (cast of interior). 

Diplodonta sp. 

Phacoldes (Miltha) claibornensls (Conrad). 

Protocardia sp. 

Crassatellites sp. 

Station 3993. Browns Mountain. S. W. McCallie, collector, 1909.1 

Flabellum cuneiforme Lonsdale. 

Endopachys maclurii (Lea). 

Periarchus pileus-sinensis (Ravenel). 

Calyptraphorus velatus Conrad. 

Turritella carinata Lea. 

Mesalia vetusta (Conrad). 

Calyptraea aperta (Solander). 

N ucula magnifica Conrad? 

Pteria sp. 

Pecten n. sp. 

Crassatellites prot~xtus (Conrad) var. 

Astarte tellinoides Conrad? 

V enericardia al ticostata Conrad var. 

Phacoides (Here) hamatus Dall. 

Phacoides alveatus (Conrad). 

Protocardia nicolleti (Conrad). 

Pitaria perovata (Conrad). 

Cytherea sp. 

Psammobia sp. 

Panope porrectoides (A~drich). 

Corbula oniscus Conrad. 

1 Veatch, Otto, and Stephenson, L. W ., op. cit., p. 295. Identified by 

T. w. Vaughan; list revised by C. W. Cooke. 

LITTLE KEG CREEK. 

A large collection of fossils that is especially 

interesting because it shows the intimate 

relationships of the Claiborne and Jackson 

faunas was obtained on the east side of Little 

Keg Creek, 7 miles north-northwest of Sandersville. Without the knmyledge of the extended 

range of certain species acquired since the 

publication of the report on the Coastal Plain of 

Georgia, this assemblage of forms would have 

been unhesitatingly referred to the upper 

Claiborne. As it stands, the numerical proportions of Claiborne and Jackson species 

recognized are practically the same, and the 

discovery of one or two additional species 

might turn the scale to one side or the other. 

When the numerical evidence is inconclusive 

in determining the age of a fauna, the philosophic course appears to be to attribute greater 

significance to the initial appearance of new 

forms than to the survival of old species. According to this reasoning the fauna at Keg 

Creek is lower Jacksonian, and it is so considered in this report. Moreover, this correlation is in accordance with that deduced from 

other stratigraphic criteria. 

Section on east side of Little Keg Cieek, Washington County, 

7 miles north-northwest of Sandersville. 

Eocene: , Feet. 

4. Coarse red sand with a few small quartz pebbles; 40 feet above the base is a 10-foot bed 

of white sand and' yellow and white clay. . 100 

3. Greenish plastic clay.. . . . . . . . . . . . . . . . . . . . . . G~ 

2. Coarse red sand grading into overlying bed. 

Fossils very abundant but restricted to 6 

inches at bottom .................... -.. -. 1! 

Unconformity (altitude 360 feet above sea level). 

Cretaceous: 

1. White sand with lenses of kaolin, to level of 

creek .................................. -- 60 

The fossils in the following list were collected 

from the base of bed 2, which is a local pocket 

filling a hollow in the Cretaceous surface. 

Station 7707. Roadside east of Little Keg Creek, 7 

miles north-northwest of Sandersville. Immediately 

above the Cretaceous. Cooke and Shearer, collectors, 

1916: 

OJ Flabellum cuneiforme Lonsdale. 

J Astrhelia burnsi Vaughan. 

Astrhelia sp. 

Volvula sp. · 

OJ Actaeon idoneus Conrad. 

Actaeon sp. 

Terebra sp. 

C Cochlespirella nana (Lea)? 

· Turritidae, 3 sp. 
DEPOSITS OF CLAIBORNE AND .JACKSON AGE IN GEORGIA. 49 

Station 7707-Continued. 

CJ Conus sauridens Conrad. 

CJ Cancellaria gemmata Conrad. 

Cancellaria, 2 sp. 

Olivella sp. 

C Ancillina scamba (Conrad). 

CJ Marginella semen Lea. 

Conomitra sp. 

J Psilocochlis mccalliei (Dall). 

Caricella n. sp. 

CJ Plejona petrosa (Conrad). 

CJ Lappru.·ia pactilis (Conrad). 

Fusinus sp. 

Clavilithes sp. 

CJ Levifusus trabeatus (Conrad)? 

C Phos sagenus (Conrad). 

C Terebrifusus amoenus (Conrad). 

J Ficus filius (Meyer). 

CJ Calyptraphorus velatus (Conrad). 

Cerithiopsis sp. 

CJ Turritella carinata Lea. 

CJ Mesalia vetusta (Conrad). , 

Epitonium sp. · 

Turbonilla sp. 

J Sinistrella americana (Aldrich)? 

Qalyptraea sp. 

CJ Lunatia minima (Lea). 

Neverita sp. 

CJ Dentalium sp. 

CJ N ucula magnifica Conrad? 

CJ N ucula ovula Lea. 

CJ Leda multilineata Conrad. 

CJ Glycymeris staminea (Conrad). 

Glycymeris sp. 

C Crenella isocru.·dioides (Lea). 

CJ Corbula oniscus Conrad. 

QJ Corbula densata Conrad. 

C Corbula alabamiensis Lea. 

C Corbula fossata var. extenuata Dall. 

CJ Pitaria perovata (Conrad). 

CJ Pitaria mortoni (Conrad). 

CJ Miltha pandata (Conrad)? 

CJ Lucina subvexa Conrad? 

CJ Phacoides alveatus (Conrad)? 

Astarte cf. A. tellinoides (Conrad). 

CJ Crassatellites protextus (Conrad) var. 

J Crassatellites n. sp.? 

J Protocardia nicolleti (Conrad). · 

CJ Venericardia planicosta (Lamarck). 

J Venericardia sp. (small). 

CJ Venericardia a1ticostata Conrad var. 

Sufficient evidence has been advanced in the 

preceding pages to show, first, that certain 

strata referred by Veatch and Stephenson to 

the McBean formation overlie limestones that 

are definitely of Jackson age and, second, that 

the fauna of the Barnwell formation appears to 

be more closely related to Jackson than to 

Claiborne faunas and that the fossiliferous beds 

at some places lie directly upon Lower Cretaceous strata. 

Below is given a systematic.outline of the 

stratigraphy of the deposits of Claiborne and 

Jackson age as it is interpreted in the light of 

the new evidence. 

STRATIGRAPHY OF DEPOSITS OF CLAIBORNE 

AND JACKSO~ AGE IN GEORGIA. 

DEPOSITS OF CLAIBORNE AGE. 

FORMATIONS INCLUDED. 

The Claiborne group receives its name from 

Claiborne Landing, Alabama River, Ala., the 

site of a town formerly of considerable importance but now almost deserted. In the type 

region the group is divided into three formations, the lowest being the Tallahatta buhrstone, the middle the Lisbon formation, and 

the upper the Gosport sand. The correlations 

between Alabama and Georgia are not precise 

enough to justify the use of any of these formation names in Georgia. 

According to the interpretation of Veatch 

and Stephenson, nearly all the deposits of 

Eocene age in Georgia were in~luded in the 

Claiborne group, and their map shows Claiborne formations extending across the entire 

width of the State. They recognized two formations within the group-a lower, the McBean 

formation with the so-called Congaree clay 

member, and an upper, the Barnwell sand. 

The recent detailed field studies of Shearer 

and Brantly have shown that the so-called 

"Congaree clay member of the McBean formation" properly constitutes part of the Barnwell formation, and studies of the fossils by 

Cooke, as set forth in the preceding part of 

this paper, have shown that the residue of their 

McBean formation in central Georgia also be~ 

longs to the Barnwell. The paleontologic evidence also indicates that the Barnwell formation is of Jackson rather than of upper Claiborne 

age, as previously supposed, and this conclusion 

is corroborated by diastrophic and other 

stratigraphic criteria. 

As restricted by the elimination of the Barnwell formation and parts of the McBean 

formation the outcropping strata of Claiborne 

age in Georgia are confined to two separate 

areas-a small irregular area in the valleys of 

McBean Creek and Savannah River, in the 

extreme eastern part of a the State, and a long, 

narrow strip in western Georgia, extending 

from Chattahoochee River eastward to a point 
50 SHORTER CONTRIBUT10NS TO GENERAL GEOLOGY, 1918. 

a few miles 

. ~- ""':a cn a 

o-l 

:s 

~ 

·c 

0 

~ ;a_ 

P=l 

'@ 

..cl 

Vl 

~ 

~ 

§_ 

~ 

~ 

-1: 

'll 

t 

:t:l 

-~ 

~-

~ .... 

~ 

N:! 

"' 6-

.... 

:~ 

~ 

c 

0 

:;:; 

ro ,bE 

§<E 

8~ 

. ~ ~ 

1~ 

8 

Ff- g 

..., 

<1> 

6 

::t5 

z 

t 

0 

".j:j 

.ro 

E 

<E 

Qj 

~ 

c 

'-

d3 

b~yond Flint River. In the intermediate region the 

Claiborne deposits are 

overlapped by strata of 

Jackson age. The beds 

of Claiborne age in the 

Savannah area retain 

the name McBean forIJ) 

.! 

:?;: 

~ ai 

0 

Iii~ 

.e; 

P:< 

~ 

§ 

I> 

d 

CIJ 

~ bil 

~ § 

1-=l 

1"/J 

i:a 

§ 

cs 

.£ 

Ll1 ~ 0 

~ 

I> 

0 

c'5 

s 

0 

.;:: 

~ 

.s 

"5 

<l> 

CIJ 

0 I 

.,..: 

"" 

~ t!l 

~ 

mation, but those in 

the ChattahoocheeFlint River area, which 

were included by Veatch 

and Stephenson in the 

McBean formation and 

Barnwell sand, will oe 

design a ted in this report 

undifferentiated Claiborne. The areal distribution is shown on the 

geologic rna p (Pl. VII). 

McBEAN FORMATION. 

NAME. 

The McBean formation was named by 

Veatch and Stephenson 1 from the town of 

McBean, in Richmond 

County, Ga., and from 

McBean Creek, . which 

forms the boundary between Richmond and 

Burke counties. 

STRATIGRAPmC RELATIONS. 

The McBean formation rests unconformably upon the Lower 

Cretaceous strata and is 

overlain by the Barnwell 

formation. The contact 

with the Barnwell is 

obscure, but it appears 

probable that there exists at least local unconformity between the 

two formations. 

In the Savannah area 

~ ~ ~ 8 ~- ~ ~ the Claiborne strata :.. 

~ !lave been overlapped by 

c'S the Barnwell formation, 

though probably not so much as farther west, 

1 Op. cit., p. 237. 

but the valley of Savannah River has been 

incised so deeply that the overlapping portion 

of the Barnwell formation has been cut away 

along the river far enough to expose the McBean 

in its proper position above the Cretaceous. 

. (See section, fig. 7 .) 

LITHOLOGIC CHARACTER AND TmCKNESS. 

The McBean formation consists chiefly of 

gray marl or sandy limestone and yellow sand 

with a little lignitio n1atter and greenish olay. 

The greatest thickness thus far observed at 

one locality is not n1ore than 80 feet, and the 

total stratigraphic thickness along the outcrop 

in Georgia probably does not greatly exceed 

· 100 feet. 

PALEONTOLOGIC CHARACTER. 

A large collection of well-preserved shells, 

chiefly mollusks, was obtained by Earle Sloan 

on the south side of McBean Creek near the 

Augusta-Waynesboro ·road. On the basis of 

these shells Vaughan 2 correlates the strata 

with the Lisbon formation of Alabama and 

Mississippi, the St. Maurice formation of Louisiana, and the Cook Mountain formation of 

Texas. The same fauna has been found at 

several localities in Aiken and Orangeburg 

counties, S. C. The following list of speoies 

from Sloan's Scarp, McBean Creek, is quoted 

from the report on the Coastal Plain: 3 

Endopachys maclurii (Lea) • 

Ringicula biplicata (Lea). 

Conus sauridens Conrad. 

Pleurotoma kelloggi Gab b. 

Pleurotoma texacona Harris. 

Pleurotoma terebriformis Meyero 

· Pleurotoma childre:ni Lea. 

Pleurotoma lesueuri Lea. 

Pleurotoma nodocarinata Gabb. 

Pleurotoma aff. P. rugosa Lea. 

Amblyacn:m stantoni Vaughan. 

Amblyacrum huppertzi var. penrosei Harris? 

Mangelia in fans Meyer. 

Marginella cohimba Lea . 

Marginella semen Lea. 

Caricella demissa var. texana Gabb. 

Caricella aff. C. pyruloides (Conrad). 

Clavelithes humerosus Conrad •. 

Fusus bellus Conrad. 

Fusus mortoni Lea. 

Lirofusus thoracicus (Conrad). 

Typhis graciLis Conrad. 

Pyrula (Fusoficul~) texana Harris. 

Leiorhynus promtus Conrad. 

Laevibuccinum prorsum Conrad. 

Mitrella mississippiensis Meyer and Aldrich. 

2 Idem, p. 240. a Idem, pp. 239-240. 
U.S. GEOLOGICAL SURVEY 

Base from U. S. Geological Survey 

1:1,000,000 scale map of the United 

States now in preparation 

F L 0 R D A 

GEOLOGIC MAP OF PART OF THE COASTAL PLAIN OF GEORGIA 

1918 

PROFESSIONAL PAPER 120 PLATE VII 

33° 

0 

l.J 

...... 

~ 

< 

~ 

~ 

[-., 

~ 

From geologic map by T. Wayland Vaughan, 

L. W. Stephenson, and Otto Veatch, with 

modifications by C. W. Cooke and H. K. Shearer 

LEGEND 

SEDIMENTARY ROCKS 

D 

Ocala limestone Barnwell formation 

(White granular limestone; (Chiefly red sands and vellowish cla'IJB 

Jcwk:ronfossils) with chert beds; JaclaJOn/os:rils) 

Undifferentiated Claiborne McBean formation 

(Sand and ca.lcarcoue marls) ( Calcareou.s nw:rl, impure limestone, sand, and clay; Claiborne foBBilB) 

UNCONFORMITY 

Wilcox formation 

(Sands, clays, and sheU marls) 

UNCONFORMITY 

D 

Midway formation 

(Sands, clays, marls, and limestones) 

UNCONFORMITY 

Ul 

::J 

0 

Upper Cretaceous sands, ILl 

u clays, and marls <I; 

(Ripley and Eutaw formations) IILl 

and Lower Cretaceous arkosic 0::: 

sands, sanily clays, and pure u 

white clays 

IGNEOUS ROCKS z 

Crystalline rocks n Q_ 
DBPOSITS OF CLAIBOR.NE AND JACKSON AGE IN GEORGIA. 51 

Phos sugenum (Conrad). 

Bnccina.nops altile (Conrad). 

Pseudoliva vetusta (Conrad) 

I.~acinia alveata Conrad. 

'1\trritella nasuta Gab b. 

'.rurritella nasuta vru:. houstonia Harris. 

Turritella arenicola Conrad. 

Turritella carinata Lea. 

Mesalia claibornensis. (Conrad). 

Tuba ru1tiquata Conrad. 

Am althea pygmaea (Lea). 

Calyptrea aperta (Solander). 

Crepiclula. lirata Conrad. 

Lu:natia eminula (Conrad). 

Natica semilunata I.~ea. 

Sigaretus declivis Conrad. 

Solarium elaboratum Conrad (young). 

Solariorbis depressa (Lea) var. 

Dentalium mmulatum Meyer. 

Nucuht ovula Lea. 

Nucula magnifica Conrad. 

Leda media Lea. 

Yoldia psammotaea Dall. 

Area rhomboidella Lea: 

Ostrea sellaeformis Conrad. 

Pecten wahtubbeanus Dall. 

Crttssatellites protextus (Conrad). 

Venericardia sp. (also at Lisbon, Ala.).' 

V e:nericardia al ticostata (Conrad). 

Venericardia plru1icosta Lamarck. 

Phacoides papyraceus (Lea). 

Bornia prima (Aldrich). 

Cytherea discoidalis Conrad. 

Metis raveneli (Conrad). 

Telli.na mooreru1a Gab b. 

Pteropsis lapidosa Conrad. 

Corbula alabamiensis Lea. 

Corbula densata Conrad. 

Corbula fossata vttr. extenuata Dall. 

AREAL DISTRIBUTION, PHYSIOGRAPHIC EXPRESSION 

AND STRUCTURE. 

So far as lmown, exposures of the McBean 

for1nation in Georgi~ are confined to Richnlond and Burke counties, forming a narrow 

strip nlong Savannah River north of _Griffin's 

Landing, 16 1niles below Shell Bluff, and covering the southern half of Richmond County in 

and north of the valley of McBean Creek. In 

general, the forn1ation is too thickly. covered 

by younger strattt to have exerted n1uch influence on the topography, but along th~ streams 

in the southern part of tho area the harder 

lodges of lin1estone fonn pron1inent bluffs. 

No irregularities have boon detected in the 

structure of the McBean for1nation. The 

upper surface of the fonnation sl.opes even1y 

seaward at the rate of about 10 feet to the mile, 

and tho underlying beds evidently have a 

slightly steeper dip. 

UNDIFFERENTIATED CLAIBORNE DEPOSITS. 

The Claiborne deposits in western Georgia 

are best exposed in the bluff on Chattahoochee 

River at Fort Gaines and in the Danville Ferry 

bluff on Flint River, 16! miles east of Americus. 

In the intermediate region the formation is thin 

and poorly exposed. Along Chattahoochee 

River Langdon 1 distinguished a lower "buhrstone" and an upper calcareous member of 

the Claiborne, but the division has not been 

recognized farther east. 

Between Flint and Chattahoochee rivers the 

Claiborne rests upon the Wilcox formation, 

from which it is separated by an erosion unconformity, which has been observed at Fort 

Gaines and at Cuthbert. The Claiborne deposits are overlain unconformably by red 

argillaceous sand of undetermined age, which 

greatly resembles contiguous beds in the 

Claiborne and is with difficulty distinguished 

from them. 

DEPOSITS OF JACKSON AGE. 

FORMATIONS INCLUDED. 

Two forn1ations of Jackson age occur m 

Georgia-the Barnwell forn1ation, including 

the Twiggs olay member, and the Ocala limestone, including the Tivola tongue. These are 

partly equivalent in age but are very different 

in lithology and present different faunal facies. 

The Ocala limestone underlies a large part of 

Florida and southern Alabama and a considerable area in the southwestern part of Georgia. 

The Barnwell formation extends from Houston 

County, Ga., beyond Savannah River an unknown distance into South Carolina. 

The Ocala lin1estone and the Barnwell formation interfinger and merge laterally into each 

other, but an arbitrary line drawn at the DoolyHouston county line delimits fairly well the 

main bodies of the formations. However, the 

Twiggs clay n1ember of the Barnwell formation 

extends southward a short distance into the 

Ocaht area and a bed of bryozoan-bearing limestone, which will be referred to as the Tivola. 

tongue of the Ocala lin1estone, projects as far 

north as Rich Hill, Crawford County, and forn1s 

an in1portant horizon marker near the base of 

the Barnwell formation in Houston, Twiggs, 

and adjacent counties. 

1 Langdon, D. W., Geology of the Coastal Plain of Alabama, pp. 744-

745, Alabama Gaol. Survey, 1894. 
52 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

BARNWELL FORMATION. 

NAME. 

Mr. Vaughan informs the present writers 

that he made a trip with Mr. Sloan into Barnwell County, S. C., for the special purpose of 

visiting the type locality of the Barnwell formation, and that he incorporated the results of 

observations made at that time in the following paragraph in the report by Veatch and 

Stephenson: 1 

Mr. Earle Sloan 2 has used the name Barnwell '' buhr 

~?ands" or Barnwell ''phase" for red ferruginous sands 

that immediately overlie the McBean formation as defined 

in this report. The type area of the Barnwell sand is in 

Barnwell County, S. C., where its stratigraphic position 

is as stated. Sloan, who has also studied the area in 

Georgia adjacent to Savannah River, states that the Barnwell ''phase" is represented by the sands that overlie the 

. fossiliferous marls of Shell Blufi. As there ·are sands of 

lower stratigraphic position but very similar in appearance 

to the Barnwell, Sloan, in several instances, confused the 

lower horizon with his Barnwell. A notable instance of 

this confusion is seen in his referring to the Barnwell the 

fossiliferous sands near Hixon's bridge on Tinker's. Creek. 3 

The horizon of the fossils of this exposure is far down in the 

McBean formation. However, it is evident that Sloan 

intended this name to apply to the red ferruginous sands 

of the upper horir.on and not to those of the lower. He 

has orally given the information that he has found Turritella carinata Lea in the Barn well sand in Barnwell County, 

S. C., and he is positive in his opinion that in the type area 

there is similarity in stratigraphic position and in both 

lithologic and faunal characters with the fossiliferous red 

ferruginous· sands overlying the McBean formation in 

Burke County, Ga. 

Although no speci:fio locality is mentioned by 

Sloan in either of his papers cited as the type 

of his "Barnwell buhr sands," it is evident 

that he had in n1ind the higher horizon which 

"irregularly overlaps the upper margin of the 

Santee marls." 4 

The stratigraphic sucoession in western 

South Carolina, acoording to Vaughan,5 is as 

follows: 

At the base are silicified clays, fuller's earth, the Congaree shales of Sloan; these are overlain by glauconitic sandy 

marls, locally with silicified shells and buhr rock, and 

calcareous beds, the Cawcaw shales and marls of Sloan, 

which are equivalent to his Warley Hill marl, Santee marl, 

an~ Mount Hope marl of the Santee area and which are 

1 Geology of the Coastal Plain of Georgia, p; 285, 1911. 

2 Handbook of South Carolina, pp. 86, 90, Columbia, S. C., Dept. Agr., 

Commerce, and Immigration, 1917; Catalogue of the mineral localities 

of South Carolina, pp. 449, 460, South Carolina Geol. Survey, 1908. 

a Catalogue of the mineral localities of South Carolina, pp. 268, 460. 

4 Handbook of South Carolina, p. 90. 

6 Index to the stratigraphy of North America: U. S. Geol. Survey 

Prof. Paper 71, p. 737, 1912. 

succeeded hy calcareous beds containing in their lower 

portion larg~ numbers of Ostrea georgiana, these beds in 

turn being overlain by red sands, the typical Bamwell 

buhr sand of Sloan. 

Inasmuch as the name Barnwell, as used by 

Veatch and Stephenson, was restricted to deposits composed almost entirely of sand, they 

employed the appropriate formational name 

Barnwell sand. For this· is substituted, in the 

present paper, the nan1e Barnwell formation, 

which is applied to a less ~hon1ogeneous composite of materials, including, in addition to the 

Barnwell sand of Veatch and Stephenson, their 

so-o3lled "Congaree" olay and the Ostrea 

georgiana zone of their MoBean formation. 

TWIGGS CLAY MEMBER. 

Extensive deposits of fuller's earth grading 

into caloareous clay of similar properties, which 

Veatch and Stephenson regarded as forming 

part of the :McBean formation and which they 

designated the "Congaree clay member of the 

McBean formation," have been found to occupy 

a much higher stratigraphie position than the 

Congaree shales of Sloan in South Carolina, 

with which they were correlated but which 

underlie the South Carolina equivn.lents of 

the MoBean forma.tion3 and to be of Jackson 

ago. These deposits are characteristically 

developed in Twiggs County, and for that reason they are here named 'Twiggs clay member. 

Exposures near Pikes Peak station, on the 

:Macon, Dublin & Savannah Railroad, are regarded as typical. The Twiggs clay is treated 

here as a member of the Barnwell forma.tion. 

STRATIGRAPHIC RELATIONS. 

In the Mississippi embayment, according to 

Berry,6 the hist third of Claiborne time was 

marked qy a greater or less emergence of land, 

which was followed at the beginning of Jackson 

time by a pronounced transgression of the sea. 

Similar conditions appear to have prevailed in 

Georgia ~ast of Flint River. The recession 

during late Claiborne time in Georgia is more 

or less cqnj ectural, but the theory of transgression in Jackson time is supported by unequivocal evidence. The Jackson sea crept 

far inland up the drowned valleys of the old 

Claiborne land area, across the beveled edges 

of. the lower Eocene and Cretaceous strata, 

o Berry, E. W., Erosion intervals in the Eocene of the Mississippi 

embayment: U.S. Geol. Survey Prof. Paper 95, p. 82, 1915. 
. . ' 

DEPOSITS OF CLAIBORNE AND JACKSON AGE IN GEORGIA. 53 

until its waves beat in places upon the crys- becomes calcareous and n1erges into limestones 

talline rocks of the Piedmont. The transgres- of the Ocala, and in the east, where it merges 

sion of the sea that took place during Barnwell into marl and oyster-shell beds of the Barnwell 

time app:ears to have been followed, in eastern formation. Along the northern margin of the 

Georgia, at least, by a slight en1ergence of the outcrops the clay men1ber is overlain with 

land which thrust back the Vicksburg shore slight unconformity by red sands that apparline. At a subsequent period, perhaps dur- ently belong also to the Barnwell formation. 

ing the :Miocene epoch, the sea again ad- This unconformity is exposed at Pikes Peak and 

vanced but did not attain its former 1naxi- Grovetown, l;>ut it evidently represents a withmum extent. drawal of the sea for only a short distance and 

FIGURE 8.-Diagram showing tho relations between the Ocala limestone and the Barnwell formation. 

The· Barnwell formation rests with at least 

local unconformity upon the McBean formation or, where that is absent, unconformably 

upon older strata. The relations of the Barnwell formation to the overlying strata are less 

obvious. On account of the similarity in appearance of much of the Barnwell to younger 

depositg of various ages, it is in many places 

di:fiicult to distinguish between them or to be certain of the identity of the ov;erlying formation. 

The Twiggs clay member occupies a position 

at the base and near the landward margin of 

the Barnwell for1nation. Although the conditions of deposition were such that the fuller's 

earth and clays of silnilar character occur as 

lenses and discontinuous beds, exposures are 

N. 

F'eot· 

500 

40 

30 

200. 

100 

Rich Hill Fort Viilley 

l Barnwell formation ~ -- Twiggs clay metnberof Barnwell formatoon 

;~::-:.---

CrystJJIIine nocks 

for a short period of time, because farther south 

the clay men1ber is conformable with the remainder of the Barnwell formation. In the 

regions north and also east of Wilkinson County, 

where the Ocala limestone is absent, the clay 

rests directly upon the surface of the Lower 

Cretaceous or is separated from it by only a 

thin bed of sand; at a few places lobes of the 

clay member overlap the Cretaceous beds entirely and rest upon the crystalline rocks of the 

Piedmont area. The most notable of these 

overlaps are at Roberts and Grovetown. 

The Barnwell formation appears to have 

been laid down at nearly the same time as the 

Ocala limestone but in a part of the sea supplied more abundantly with sand and mud, and 

s. 

Byrom.v.ii.J.e Gum.~ek 

l 1 

. ::lo 

St>alcvel o '-------------------------=~------==--~ 

0._, __ _..9 __ ---'-'-10 __ _.1~ Miles 

FIGURE 9.-Scction from Rich Hill, Crawford County, to the mouth of Gum Creek, Crisp County, Ga. 

abundant in a belt extendingfromDoolyCounty the lateral transition from the siliceous sedito Columbia County, more than halfway across ments of the Barnwell to the limestones of the 

the Stn.te. The mode of origin of the Twiggs Ocala is gradual. The Tivola tongue of the 

clay n.nd the agencies that produced its peculiar Ocala limestone, which intrudes far into the 

physical properties are not clearly understood, main area of th~ Barnwell, represents a ternbut its situation indicates that it may have been porary invasion of the calcareous phase of deformed in long, narrow lagoons or bays to which position beyond its usual limits. The supposed 

coarse sediments had only occasional access but relations between the Barnwell formation and 

which appear to have had free communication the Ocala limestone are shown in the accomwith theopenseain thesouthwest, where the clay parrying diagram (fig. 8) and section (fig. 9}. 
0 54 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

At the base of the Barnwell formation along 

Savannah River is a bed of impure limestone 

or marl that contains large numbers of shells 

of Ostrea georgiana Co:rirad, a huge oyster, some 

specimens of which attained a length of nearly 

2 feet. This species appears in eastern Georgia 

to be restricted to the lower part of the Barnwell 

formation. The Ostrea georgiana zone has been 

traced for m.iles into South Carolina, and it 

seems probable that this zone represents a 

tongue of the Cooper marl of South Carolina 

and that it is continuous beneath the cover of 

younger deposits in sou the as tern Georgia with 

the Ocala limestone of Georgia and Florida. 

Local oyster beds that appear to oecupy the 

same stratigraphic position as the bed on 

Savannah River have been seen as far west as 

Danville. 

LITHOLOGIC CHARACTER. 

The greater part of the Barnwell formation 

is sandy, comprising widespread deposits of 

coarse brilliant-red sand which appears to 

derive its color from weathered glauconite, 

together with locally indurated beds of gray 

sandstone which in places approaches quartzite in texture, and basal conglomerates resembling the gravels of the Pleistocene terraces. The sand in many localities incloses 

masses of flint, many of which are fossiliferous 

and appear to represent the silicified remnants 

of limestone lenses. Some of the flint is in 

scattered lumps, but most of it is restricted to 

well-defined zones. 

The Twiggs clay member of . the Barnwell 

consists typ'ically of greenish-gray siliceous clay 

of low specific gravity, not plastic but breaking 

with a hackly fracture and exhibiting all the 

J=>roperties of f~er; s earth. The fuller's earth 

grades laterally into calcareous clay of similar 

appearance and properties and thence into 

argillaceous limestone. Some of the clay is 

free from grit, but most of it is interbedded 

with thin layers of sand. 

"At places where the fuller's earth was not 

deposited and north of the limit of clay deposition beds of. yellowish-green glauconitic sand 

extend to the base of the Barnwell formation. 

Near the base of the formation are lo.cal beds 

of lignite, shaly aluminous sandsto;ne, quartzite, and completely silicified sandy limestone. 

THICKNESS. 

1n eastern Georgia the thickness of the Barnwell formation has not been accurately determined, because the contact with the overlying 

formations is uncertain. In the Shell Bluff section 65 feet belong to this formation. At Louisville, whichisabout 10milesfrom the CretaceousBarnwell contact, 100 feet of beds referred to the 

Barnwell formation are exposed from Rocky 

Comfort Creek up to the level of the town. In a 

deep well near Louisville the top of the Cretaceous is thought to have been reached at a 

depth of about 350 feet, 1 but this thickness 

probably includes som.e Claiborne strata in 

addition to the Barnwell formation. The available uvidence does not indicate a thickness 

greater than 200 feet for the Barnwell formation in eastern Georgia, and it may be considerably less. 

In Twiggs County the beds referred to the 

Barnwell formation extend from the surface of 

the Lower Cretaceous in the Dry Branch kaolin 

mines, at an altitude of 400 feet above sea 

level, to the tops of the higher hills in the 

vicinity of Pikes Peak, at an altitude of 625 

feet. The formation is little more than 200 

feet thick. 

In Houston County, as the Tivola tongue of 

the Ocala limestone thickens the Barnwell formation becomes thinner, and only about 100 feet of 

the Ross Hill section may be referred to it. 

The Twiggs clay member attains its maximum thickness near Pikes Peak in Twiggs 

County, where fuller's earth occurs at two distinct horizons separated by a bed of greenish fossiliferous sand, the whole being 100 feet thick. 

In Houston County the 100 feet of fuller's 

earth, calcareous clay, and sand of the Barnwell formation may be considered as belonging 

almost entirely to the Twiggs clay member. 

South of these counties the clay becomes thinner as the underlying Tivola tongue of the 

Ocala limestone thickens. To the northeast, 

also, the Twiggs clay becomes thinner along 

the strike, and at few ·places in Jefferson and 

Columbia counties is it as thick as 20 feet. 

PALEONTOLOGIC CHARACTER. 

The fauna of the Barnwell formation has already been discussed at some length (pp. 42-49). 

In general terms, it is an assemblage of shallowwater or littoral species which inherited many 

elements from the preceding upper Claiborne 

or Gosport fauna but which includes a number 

of species not known from older deposits. 

1 McCallie, S. W., A preliminary report on the underground waters of 

Georgia: Georgia Geol. Survey Bull. 15, p. 129, 1908. 
DEPOSITS OF CLAIBORNE AND JACKSON AGE IN GEORGIA. 55 

The Mollusca constitute the dominant element, being represented by numerous genera 

and species. Bryozoa are abundant in what 

n1ay be regarded as transition beds between 

the Barnwell and laterally adjacent formations 

but are scarce in n1ore typical deposits. Corals 

are repr~sented by a few very prolific species, 

and ec4inoderms by P e'riarchus pileus-sinensis 

and Mortonella quing_uefaria. The most significant vertebrate thus far discovered is the huge 

zeuglodon Basilosaurus cetoides, which is particuhu·ly valuable as a guide fossil. 

The Twiggs clay 1nember of the Barnwell 

forn1ation has yielded a small flora which assists in correlating isolated ~xposures of the 

fonnation with one another but which presents 

inconclusive evidence for determining the age 

of the deposits because the floras of the upper 

Claiborne and lower Jackson are very similar. 

As originally described by Berry/ the flora 

included only 17 species of plants, all of thmn 

new, but recent collections have increased. the 

total to 26, and n1ost of them have since been 

discovered elsewhere. The following list with 

conuncnts has been fm·nished by Prof. Berry: 

Flora of the 'Pwiggs clay rnernber of the Barn 'Well formation. 

~ ~ ~ -ci ,!. ::s § . s ~ .£ 

~ o:! ~ d . C1l .S§ ..... s:= t: s:=._3 II< o:~ ..... 0 §·.§ ~o:! s;+> o. 

~ ..c ~ -tJS ~ IJ)o .~ 0 

~ o:! H 0 ~ -------------1---------- Acrostichum georgianUJ:?-.... . . . . . . . . . . . . X X .... Arund? pseudogoeJ?perti......... . . . . X X X X 

Carpolithus naJU.SOldes ...... ~ ...................... . Castanea claibornensis ................. · .............. . Cassin. georgiana ..................................... . Conocarpus eocenica..... . . . . . . . . . . . . . . . . . . . . X X 

Cupanites nigricans a .................•...•.. I •••••••• 

9inmtmomu~ au&'ustum. . . . . . . . . . . . . . . . . X ....... . Dodpnaea v1scoso1des.... . . . . . . . . . . . . X X . . . . X 

Ficus claibornensis .... ~.... . . . . . . . .................. . ]i"icus newtonensis. . . . . . . . . . . . . . . . . . . . . . X ....... . Malapoennasp ...................................... . ~~im~s! tes geo:gian us.... . . . . . . . . . . . . . X X ....... . M OJlllSia amencn.na.......... . . . . . . . . . X ........... . Pestalozzi tes minor ................................ . Pisonia cla.ibornensis............ . .. . X ........... . Pistia claibornensis ................................ . Pteris inq uireuda.... . . . . . . . . . . . . . . . . . . . . X ....... . Pota.moF'eton megaphy 11 us. . . . . . . . .................. . lthi~opJtora eo(:enica. . . . . . . . . . . . . . .................. . Sapmd us georguma.. . . . . . . . . . . . . . . . . X X ....... . Sophora claiborneana... . . . . . . . . . . . . . . . . . X . . . . X 

Sophora wilcoxiana.... . . . . . . . . . . X X ........... . Sphaerites claibornensis ............................. . Tenninalia phaeocarpoides....... . . . . . . . . . . . . . . . . X 

'l'hrinax eocenica................ . . . . X X 

"Oreon River formation of Wyoming. 

To summarize this list, it may be noted that of the 26 

species found in Georgia 1 comes up from the Wilcox, 3 

occur in the St. Maurice, 8 occur in the Yegua, 10 in the 

Lisbon, and 3 in the Gosport, making 13 of the 26 that 

occur in known Claiborne. One additional E"pecies occurs 

in the Green River of Wyoming. 

Six of the Georgia species occur in the Jackson. Although 

the Twiggs clay flora is thus apparently more like the Claiborne flora of other areas than it is like the Jackson, two 

features make this similarity more apparent than real. 

One is the fact that the continental deposits in Texas referred to the Yegua, in which several of the Georgia species 

reappear, are believed by me to be of Jackson age. The 

second modifying factor is that the buik of the known Claiborne flora is found in the upper Claiborne and that this 

upper Claiborne flora is but slightly modified in passing 

over into the Jackson. 

It should not be overlooked that 10 species, 

or 38 per cent of the total number, have not 

yet been found elsewhere and that subsequent 

collecting may change the relative proportions 

of Claiborne and Jackson species. The 26 

species of plants lmown to science out of the 

hm1dreds that must have existed at the san1e 

.time form so insignificant a part of the flora 

that they ought not to be considered as necessarily representative of the whole. :Moreover, 

as pointed out by Ulrich,2 paleobotanists are 

prone to place disputed formations lower in the 

time scale than is indicated by the marine 

invertebrates, because the plants attain their 

greatest developmertt during the emergent 

interval preceding 'the introduction of the new 

marine fauna. 

. AREAL DISTRIBUTION. 

The Barnwell formation extends in a broad 

belt fron1 Savannah River nearly to Flint 

River, but in the western half of this belt, the 

area lying west of Oconee River, the formation 

is intermediate in character between the typical Barnwell and the Ocala limestone, merging 

in to the Ocala toward the south, or seaward, 

and toward the southwest. In the description 

by counties the southwestern boundary of the 

formation is arbitrarily placed at the HoustonDooly county line, although the Twiggs clay 

member and perhaps also some of the overlying 

red sands extend for some distance south of this 

line, and a wedge of bryozoan-bearing limestone (the Tivola tongue of the Ocala limestone) projects into the Barnwell formation in 

I-Iouston, Twiggs, and adjacent counties, an'd 

2 Ulrich, E. 0., Correlation by displacements of the strand line and 

1 :Berry, K W., ~rl1o Upper Cretaceous and l<~ocene floras of South the function and proper use or fossils in correlation: Geol. Soo. America 

Carolina and Georgia: U. S. Geol. Survey Prof. Paper 84, p. 129, 1914. Bull., vol. 27, p. 465, 1916. 
56 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

forn1s an important horizon marker near the 

base of the formation. (See n1ap, Pl. VII, and 

section, fig. 8.) 

The Barnwell formation occupies considerable areas in Burke, Richmond, Jefferson, 

Glascock, Washington, Wilkinson, Twiggs, and 

I-Iouston counties and smaller parts of adjacent 

counties. The northern boundary is very 

irregular, the plain forming the surface of the 

formation having been deeply dissected by 

strmtms that have cut their valleys down into 

the Cretaceous strata, leaving promontories and 

erosional outliers of the Barnwell in the interstream areas. The southern boundary is likewise irregular, but in reverse order,.having long 

salients extending down the river valleys. 

The Twiggs clay member in eastern Georgia 

is confined chiefly to the northern edge of the 

area occupied by the Barnwell formation, but 

toward the west its outcrop widens until it 

practically coincides with that of the formation 

as a whole. It is characteristically developed 

near Grovetown, Columbia County, and outcrops have been noted at short intervals from 

that locality to Rich Hill, in Crawford County. 

PHYSIOGRAPHIC EXPRESSION. 

· The unconsolidated sands of the Barnwell 

formation have yielded readily to erosional 

agencieB and, especially along the faU line, 

have been deeply trenched. The harder sandstones have resisted better and in a few places, 

as at Browns Mountain, form hills of considerable height. In most places the Twiggs clay 

member is overlain by beds of sand, but where 

not so protected it shows a tendency to form 

barren "washes" or grassy slopes. 

STRUCTURE. 

The Barnwell formation strikes approximately northeastward. 

From exposures along the Macon-Perry 

road (National Highway) in Houston County 

the slope of the Cretaceous surface is estimated 

at more than 12 feet but not more than 20 

feet to the mile. The dip of the Barnwell 

formation is a little less than that of the 

surface upon which it lies and is probably 

about 10 feet to the mile. 

"In Twiggs County the slope of the upland 

plain is 9 feet. to the mile measured parallel to 

the Macon, Dublin & Savannah Railroad from 

Pikes Peak to Danville (southeast). The dipof the Barnwell formation, which is a little:. 

steeper than the slope of the plain, is probably 

between 10 and 15 feet to the mile. 

In the eastern part of the State the upper 

surface of the Lower Cretaceous beds is very 

irregular, and the dip can not be stated with 

certainty. The base of the Barnwell formation in this region slopes from 500 feet above 

sea level at Grovetown to 80 feet at Griffin's 

Landing, a fall of 420 feet in 36 miles, or a. 

little more than 11 feet to the mile toward 

the southeast. 

Except for the slight tilt townrd the southeast the beds of the Barnwell formation are, 

practically undisturbed. The only indica-. 

tion of later movements detected is a local. 

anticline, cut through by the railroad at. 

Pikes Peak, in which the limbs dip 4 ° SE. and 

3°NW. 

OCALA LIMESTONE. 

NAME. 

In 1892 Dall 1 applied the name Ocala to· 

limestone deposits exposed in the vicinity of· 

Ocala, Marion County, Fla., and some years. 

later the same author described a number of· 

species of mollusks from the Ocala limestone 

and published a partial list of the species. 

found in it. 2 This fauna was first recognized in Georgia by Vaughan, 3 who correlated 

the outcrops of limestone in Flint River near· 

Bainbridge with the Ocala "zone," and the. 

name Ocala limestone was recently employed. 

by Cooke 4 in referring to the same deposits. 

The Ocala limestone as defined in this report. 

includes the greater pa!-t of the Vicksburg· 

formation of Veatch and Stephenson 5 as well 

as most of the Jackson formation of the same, 

authors. The Tivola tongue of the Ocala lime-· 

stone is typically exposed at the quarry of · 

the Planters Limestone Co., 2 miles south of· 

Tivola. (See p. 76.) 

1 Dall, w. H., Correlation papers-Neocene: U.S. Geol. Survey Rull .. 

84, p. 103, 1892. 

2 Dall, ·w. H., Contributions to the 'l'ertiary fauna of Florida, pt. 6: . 

Wagnet Inst. Trans., vol. 3, pp. 1219-1654, 1903. 

a Vaughan, T. W ., A Tertiary coral reef near Bainbridge, Ga.: Science, 

new ser., vol. 12, p. 873, 1900; The Eocene and lower Oligocene coral 

faunas of the United States: U. S. Geol. Survey Mon. :39, p. 31, 1900. 

c Cook-e, C. W ., The age of the Ocala limestone: U. S. Geol. Survey 

Prof. Paper 95, p. 110, 1915; The stratigraphic position and faunal asso- · 

ciates of the orbitoid Foraminifera of the genus Orthophragmina from_ 

Georgia and Florida: U. S. Geol. Survey Prof. Paper 108, pp. 109-113,, 

1917 (Prof. Paper 108-G). 

G Veatch, Otto, and Stephenson, L. W ., op. cit., pp. 296-362. 
DEPOSITS OF CLAIBORNE .AND .JACKSON AGJ<j IN GEORGIA . 57 

STRATIGRAPHIC RELATIONS. 

The relations of the Ocal~ limestone to both 

"the underlying and the overlying formations 

are imperfectly known. At its northeastern 

limits the formation overlaps upon older 

strata (see fig. 8, p. 53), and similar conditions 

1n11y prevail toward the west, but whether 

the overl11p extends all the way to Chattahoochee River is uncertain. At any rate, the 

Cl11iborne deposits are not completely over-

. The Ocala limestone appears to have been 

deposited almost contemporaneously with the 

Barnwell formation, with which it is interbedded in the transition area. The Tivola 

tongue, which extends for many miles into the 

area occupied by the Barnwell, lies beneath the 

larger mass of that formation, but in most 

places is underlain by thin sandy beds that are 

classed with the Barnwell. 

lapped in the west, as in central Georgia. LITHOLOGIC CHARACTER. 

The Ocala limeston~ is overlain by the The Ocala limestol).e consists chiefly of soft 

Vicksburg formation, but the Vicksburg has white or cream-colored limestone that in 

been eroded so much that its original relations places is composed almost entirely of the reto the Ocala are very obscure. Where the mains of Foraminifera and Bryozoa. The 

two formations have been observed in contact lower portion is more arenaceous and in places 

no evidence of physical break in sedimentation approaches sandstone in composition. In the 

between them has been detected. In the transition. area at the northeastern extremity 

vicinity of Bainbridge the upper surface of of the formation the Ocala beoomes highly 

the Ocala is exceedingly irregular, having argillaceous and merges into the Twiggs clay 

suffered considerably from degradational agen- member of the Barnwell formation. 

cies, but how 1nuch this unevenness is due to On exposed surfaces at many localities the 

solution and disintegration of comparatively pores of the soft limestone have been filled up 

recent date or to what extent it antedates by infiltration of calcium carbonate, which has 

the deposition of the overlying beds is at pres- "case hardened" the outer layers of the rock 

ent unknown. The Vicksburg in this region into hard semicrystalline limestone. That 

is apparently represented mostly by scattered processes of silicification have been active in 

lumps of residual flint, the main overlying certain regions is shown by large masses of 

forn1ation belonging to the Apalachicola group .. white flint or silicified limestone that are strewn 

·The following note is introduced through the over the surface or ·embedded in residual sand, 

-courtesy of Messrs. Vaughan and Bassler: but such action has by no means been confined 

In 1915 Vaughan 1 pointed out that a species of coral to the Ocala limestone, as it has attacked 

referred to by him as Orbicella cellulosa (Duncan) is com- the Vicksburg and Chattahoochee limestones mon to Vicksburg deposits at Vicksburg, Miss., to the as well. 

basal Chattahoochee at Bainbridge, Ga., to the 'l.'ampa 

formation at Tampa, Fla., and to the Antigua formation 

·Of Antigua. Recent unpublished results obtained by 

Vaughan from his studies of the corals and associated 

organisms in the base of the Chattahoochee formation 

and in the Antigua formation of Antigua indicate that 

these deposits are of middle Oligocene age and that they 

are stratigraphically only a little above the upper Vicksburgian Byram calcareous marl 2 of Mississippi. Bassler 

has identified Bryozoa characteristic of the Marianna 

limestone (middle Vicksburgian) in chert found associated 

with the corallifet·ous chert in the vicinity of Bainbridge 

but not in the same chert masses as the corals. As the 

Bryozoa and the corals have not been fo~md together, 

they seem to represent different horizons. A considerable 

number of mollusks occurring also at Vicksburg have 

been listed from these beds by Dall, 3 but a critical comparison of the faunas has not been attempted. 

1 Cnrnoglo lnst. Washington Year Book 13, p. 360, 1915. 

s Defined by C. Wythe Cooke in Correlation of the deposits of Jackson 

·and Vicksburg ages In Mississippi and Alabama: Washington Acad. 

Sci. Jour., voi. 8, pp. lSG-198, 1918. 

s Doll, W. H., A contribution to the invertebrate fnunaofthe Oligocene 

·bods of ]<'lint lllvor, Ga.: U. S. Nat. Mus. Proc., vol. 51, pp. 48&-489, 1916. 

TmCXNESS. 

Reliable data concerning the thickness of the 

Ocala limestone are lacking. In a well at 

Albany 4 the drill is believed to have entered 

the Claiborne at a depth of about 280 feet, and 

the total thickness of the Ocala in this vicinity 

probably does not greatly exceed 300 feet. 

At Bainbridge the drill penetrated 7 50 feet of 

limestone, but how much of this is of Jackson 

age is unknown~ The Tivola tongue in few 

.places exceeds 40 feet in thickness and is commonly much thinner. 

PALEONTOLOGIC CHARACTER. 

The Ocala limestone contains a large and 

characteristic bryozoan fauna., of which about 

90 species have been found in Ge~rgia. 5 

'Georgia Geol. Survey Bull. 26, pp. 317-318, 1911. 

6 Canu, Ferdiuand, and Bassler, R. S., manuscript list. 
58 SHORTER CONTRIBUTIONS TO. GENERAL GEOLOGY, 1918. 

Foraminifera are exceedingly abundant and 

in places constitute a large part of the rock, 

but lists are not yet available. The orbitoid 

Foraminifera are abundant, being represented 

by several species of Orthophragmina, both 

smooth and stellately marked, and also by 

species of Lepidocyclina. Species of both 

genera have been erroneously referred to 

Orbitoides mantelli, which is the type species 

of the genus Lepidocyclina and appears to 

be peculiar to the horizon of the Vicksburg 

represented by the Marianna limestone.· Operculina is common in the middle or lower part 

of the formation. 

tremity the Ocala is interbedded with or transitional to the Barnwell formation. Northeast 

of tllis line the lowea portion of the formation, 

the Tivola tongue, extends into the Barnwell 

area through Houston, Twiggs, and Bleckley 

counties, and parts of Wilkinson and Crawford 

counties. Throughout much of its areal extent 

the formation is concealed from view by a thin 

cover of younger strata, mainly sands, but it is 

exposed along watercourses, and its presence 

in the interstream areas is indicated by lime 

sinks and flint boulders. 

PHYSIOGRAPmC EXPRESSION. 

Echinodermata attained during Ocala time a The ready solubility of the Ocala limestone 

greater ,development than during any other has assisted in the degradation of its surface. 

part of the Tertiary period in the Atlantic and In the region lying between Flint and ChattaGulf Coastal Plain area. These forms appear hoochee rivers underground solution has been 

to be very much restricted in vertical range, extensive, and the plain is dotted with lime 

and it seems probable that more detailed work sinks and ponds, ranging from shallow saucerwill result in the discrimination of several zones shaped circular depressions to sinks of considerby means of them. Periarchus pileus-sinensis able size. The region is a flat low-lying plain, 

appears to be restricted to the Tivola horizon; in marked contrast to the high sandy plateau 

other species, which occur higher in the forma- upheld by the Alum Bluff formation east of 

tion, are Oidaris georgiana, Laganum? crustu- Flint River. · Small surface streams are not 

loides, Schizaster floridanus, Macropneustes abundant, much of the drainage going through 

mortoni,' Oassidulus (Rhynchopygus) depressus, subterranean channels. 

Oassidulus (Pygorhynchus) conradi, Oassidulus In the northeastern part of the area occupied 

(Pygorhynchus) georgiensis, Eupatagus caroli-. by the Ocala limestone, solution appears t(} 

n~nsis, Oliogopygus haldermani, and Agassizia have played a part in the formation of topoconradi. graphic forms subordinate to that of mechanA rather extensive molluscan fauna is con- ical agencies. The harder limestone ledges. 

tained in the Ocala limestone, but compara- have resisted erosion better than the clay de-· 

tively few forms have been preserved well posits with which they are interbedded, with 

enough for determination. A noteworthy ex- the result that the limestone stands out in 

ceptio:Q to this is found in the pectens, which steep slopes or bluffs. 

occur in great abundance and are beautifully STRUCTURE. 

preserved. Pecten perplanus, a typically Jack- The Ocala limestone has not been studied in 

·son species, is present, together with several sufficient detail to permit accurate determina-· 

closely related species or varieties. Amusium tion of its structure, and the scarcity of recogocalanum, originally described from Florida, is nized horizon markers makes such determina-· 

widely distributed in Georgia. tion difficult. The formation as a whole ap-· 

AREAL DISTRIBUTION. pears to be inclined very gently seaward at. 

The Ocala limestone occurs at or near the 

surface over a broad belt lying chiefly in the 

drainage basins of Chattahoochee and Flint 

rivers .. (See geologic map, Pl. VII.) The belt 

crosses Chattahoochee River between Saffold 

and a point about 4 miles above the mouth of 

Flint River, an airline distance of . nearly 30 

miles; thence it extends northeastward to the 

Dooly-Houston county line, but at that exthe rate of probably 10 feet to the mile. Gen-· 

tie flexures may exist, but none have been 

detected. 

ECONOMIC GEOLOGY. 

The greater part of the workable limestones. 

and marl deposits of the Coastal Plain of Geor-· 

gia pertain to the Ocala limestone. These have. 

been treated in detail by Brantly.1 

1 Brantly, J. E., Georgia Geol. Survey Bull. 21, 1916. 
DEPOSITS OF CLAIBORNE AND JACKSON AGE IN GEORGIA. 59 

SUMMARY. 

The· differences between the interpretation 

of the stratigraphy of Georgia here offered and 

that of Veatch and Stephenson may be brit3fly 

summarized as fo,llows: 

The deposits of Claiborne age, which they 

mapped as extending uninterruptedly across 

the entire width of the State, have been restricted to two areas, one along Savnnnah 

River and McBean Creek and the other between 

Flint and Chattahoochee rivers: The deposits 

of Claiborne age in the east retain the name 

McBean formation, but those in the west are 

called undifferentiated Claiborne. 

The Barnwell Sfi;nd, which they regarded as 

of upper Claiborne age, is raised in the time 

scale and placed in the Jackson epoch with the 

nan1e altered to Barnwell formation. The socalled'" Congaree clay member of the McBean 

formation" is placed bodily in the Barnwell 

forn1ation and, together with calcareous clays 

which were already correlated with the Jackson formation, is renamed Twiggs clay member, the name Congaree being inappropriate 

becnuse the clay is now known to be much 

younger than the typical Congaree shales of 

Sloan. Those parts of their McBean formation left after the· elimination of the undifferentiated Claiborne and the typical McBean 

formation are here included in the Barnwell 

for1nation. 

The littoral facies of th~ Bnrriwell fauna bears 

an exceedingly close relationship to the littoral fauna of the Gosport sand of Alabama 

but is tl'ansitional between that fauna and 

typical Jackson faunas and contains enough 

distinctive species to justify the reference of it 

to the Jackson epoch. The discovery of evidence of an extensive transgression of the sea 

upon the old land surface at the beginning of 

Barnwell time corroborates the reference of the 

forn1ation to the beginning of a new stage 

rather than to the closing period of an old. 

The greater portion of the Vicksburg formation of Veatch and Stephenson is transferred 

to the Jackson epoch, under the name Ocala · 

li.Inestone, and the Jackson formation of their 

usage is divided between the Ocala limestone 

and the Barnwell formation. The residue of 

the Vicksburg formation is left untouched for 

the present. 

LOCAL DETAILS. 

McBEAN FORMATION. 

.ilfcBean.-Several sections along the south 

side of Mc.Bean Creek, southeast of MoBean 

station, are given by Vaughan/ and locn.lities 

farther upsb.ream are described by Br.antty.2 

These descriptions show that the McBean forn1ation is variable within short distances. 

East of the Cent~al of Georgia Railway the 

formation consists largely of sand, clay, and 

lign.itic material, with n1arl only near the base 

of the section. West of the railway the n1arl 

beds becmne much thicker, reaching a thiekness of over 50 feet, all above creek level, on 

the Newton Palmer property. The two following sections a.re typica.l of the beds east and 

west of the railway: 

Section on Newton Palmer property, McBean Cre6k, on west 

side of Central of Georgia Railway. 

[:Measured by J. E. Brantly, op. cit., p. 46.] 

Barnwell formation ( ?) : . .Feet. 

6. Concealed interval; sandy soil on top of hill.. 34 

McBean formation: 

5. Soft white argillaceo.us "rotten" limestone. .. . 7 

4. Medium hard highly fossiliferous limestone; 

fossils poorly preserved.................... 2 

3. Soft, "rotten" to consolidated cream-colored 

argillaceous limestone. . . . . . . . . . . . . . . . . . . . . 45 

2. Blue glauconitic clay like fuller's earth...... 6 

1. Hard arenaceous fossili£erous limestone. . . . . . . 2 

Creek bed. 

96 

Section in g'ully on south side of McBean Creek, a quarter of 

a mile east of the bridge on the Augusta-Savannah public 

road. 

[Measured by C. W. Cooke.] 

Barnwell formation (?): Feet. 

6. Brilliant red massive a~illaceous sand, very 

coarse in lower portion . . . . . . . . . . . . . . . . . . . . 20 

McBean formation: 

5. Coarse incoherent yellow sand; at the top a locally indurated ledge of friable white sandstone, which elsewhere is represented by 

carbonaceous sand. . . . . . . . . . . . . . . . . . . . . . . . 30 

4. Coarse quartz sand in a matrix of greenish· 

yellow clay.............................. 4 

3. Fine yellow sand, incoherent at top, argillaceous below, with patches of calcareous and 

carbonaceous, almost ligi1itic material...... 5 

2. Soft fine-grained sandy gray calcareous marl, 

with a few fragments of shells and some hard 

nodules.................................. 3 

1. Concealed interval to creek level, about...... 30 

92 

t Veatch, Otto, and Stephenson, L. W., op. cit., p. 242. 

~Brantly, J. E., Report on the limestones and marls of the Coastal 

Plain of Gilorgia: Georgia Geol. Survey Bull. 21, pp. 44-50, 1916. 
60 SHOR.TER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

In the bottom of the gully at the second 

locality were found a few fragments of fossiliferous chert that were probab-ly derived from 

the red sand, bed 6 of the section. The relations of the upper bed to bed 5 are somewhat 

obscure, but it seems probable that there is an 

erosional unconformity between them. 

On the Waynesboro road, at the foot of the 

hill leading down to McBean Creek, a few fragments of shells were seen in yellow sand, 

apparently bed 3 of the preceding section. 

The shells are not disseminated throughout 

the sand but are segregated into sinall patches 

of shell marl. This is probably the horizon 

from which Sloan obtained the large collection 

of fossils listed on pages 50-51. 

Silver Blu_(f.-The southernmost exposure of 

the Lower Cretaceous beds and the best section 

of the lower part of the McBean formation is 

seen at Silver Bluff, 27 miles· by river below 

Augusta and 12 miles above Shell Bluff. 

Section at Silver Bluff, Savannah River. 

[Described by H. K. Shearer. Measured at west end of bluff on South 

Carolina side.] 

Recent: 

8. Soil; gray sandy loam .................... . 

Eocene-McBean formation: 

Feet. 

2 

Shell Bluff.-Shell Bluff, on Savannah River, 

163 miles from the mouth of the river, is one 

of the classic localities in the study of the geology of the Coastal Plain of Georgia and South 

Carolina and has been described by many geologists during the last century. The 140 to 150 

feet of beds exposed there have previously 

been correlated with various formations ·from 

the Claiborne to the Vicksburg. In the report 

on the geology of the Coastal Plain of Georgia 

the whole series was referred to the Claiborne 

group, and the line of division between the McBean formation and the Barnwell sand was 

placed at the top of the Ostrea georgiana zone. 

However, Vaughan 1 says in that report: 

The McBean formation includes two paleontologic horizons. The lower one * * * is especially characterized by Pleurotoma nodocarinata Gabb, Turritella nasuta 

Gabb, Turitella nasuta var. houstonia Harris, Ostrea sellaeformis C;:nrad, Pteropsis lapidosa Conrad, and Co'rbulajossata Meyer and Aldrich. 

A higher horizon is represented especially well along 

Savannah River, between Shell Bluff, upstream, and Griffin's Landing, downstream. Along this stretch of the river 

a prominent ledge, largely composed of Ostrea georgiana 

Conrad, forms the top of the McBean formation. Although 

this formation could be subdivided along Savannah River, 

it was found impracticable to extend the subdivision westward, for which reason the Ostrea georgiana bed is considered as constituting its upper portion. 

7. Coarse mottled argillaceous sand. . . . . . . . . . . . 6 

6. Lenticular mass of crumbly, sandy ironstained clay, somewhat like fuller's ea.rth. 

Maximum thickness .................. _ . . . 6 The red sand overlying the Ostrea georgiana 

5. Coarse red and yellow cross-bedded sand .... 10 zone was called the Barnwell san<;l, which was 

4. Layer of sand cemented by limonite........ .1 then supposed to be of Claiborne age. Since 

Unconformity. the publication of the Coastal Plain report, 

Lower Cretaceous: however, R. S. Bassler 2 has identified Bryozoa 3. Laminated yellow and brown sandy clay, maximum.............................. 2 characteristic of the Jackson deposits from the 

2. Blue highly plastic clay free from grit....... 2. 5 Ostrea georgiana zone, and careful stratigraphic 

l. Yellow-gray arenaceous clay· · · · · · · · · ·- · · · · 2. 5 work has resulted in the recognition of this 

31. 1 

The strata classed as Lower Cretaceous were 

slightly folded prior to the deposition of the 

overlying material, but there is no evidence 

elsewhere of any considerable distlirbance of 

the beds. The beds above the unconformity 

are believed to lie at the same horizon or a 

little lower than the marl beds of Claiborne 

age at Shell Bluff, but as they were deposited 

very near the shore line they contain no calcareous material. If the correlation of these 

'beds is correct, the Cretaceous surface dips 

beneath the river level near the mouth of 

McBean Creek. 

horizon in the Barnwell formation at numerous 

localities in central Georgia. 

The following generalized section at Shell 

Bluff is made up from the writers' notes and 

from sections previously published. 3 The Ostrea georgiana zone occurs only downstream 

from the boat landing, but the underlying 

beds are exposed in the steep part of the bluff 

above the landing. 

1 Georgia Geol. Survey Bull. 26, p. 240, 1911. 

2 Oral communication. 

a For more detailed sections s~e Sloan, Earle, Catalogue of the mineral 

localities of South Carolina: South Carolina Geol. Survey, 4th ser., Bull. 

2, pp. 271-272, 1908. Veatch, Otto, and Stephenson, L. W ., Georgia 

Geol. Survey Bull. 26, pp. 243-247, 1911. Brantly, J. E., Georgia Geol. 

Survey Bull. 21, p. 51, 1916. 
. DEPOSITS OF CLAIBORNE AND ;r ACKSON AGE IN GEORGIA. 61 

Generalized section at Shell B,lu.ff. 

Barnwell formation: :Feet. 

7. Apparently ~11 red argillaceous saud to level 

of upland plain. The surface of the plain 

is covered by several feet of loose gray sand, 

but clayey sand for road building is obtained 

from shallow trenches along the roads...... 35 

6. Ostrea georgiana zone. The base of the oyster 

bed is 80 feet above zero water level in the 

river, and although exposures are not contiuous, oysters are found up to 110 feet above 

water level. The oyster ledge at the base of 

the zone contains very large shells in a matrix 

of yellowish sand. Above this is a bed of 

calcareous conglomerate containing quartz 

pebbles. Above the conglomerate bed the 

oysters are in a matrix of yellowish marl or 

hard calcareous clay, having some of the 

characteristics of fuller's earth. The matrix 

of the oyster shells contains Bryozoa of the 

Rich Hill facies of the Jackson fauna ..... . 

McBean formation: 

30 

5. Concea.led interval between th~ upper and 

lower bluffs. Covered by talus from the 

Ostrea georgiana zone and other overlying 

formations but probably is a bed of sand.. 10 

4. Moderately hard to hard light-colored marl, 

with few fossils. . . . . . . . . . . . . . . . . . . . . . . . . . . 9 

3. :Ledge of hard brown coquina-like rock, with 

numerous hollow casts of fossils..... . . . . . . . . (3 

2. White to purplish sandy limestone, made up 

largely of fossils. This is the most important 

fossiliferous stratum of the McBean formation, and Vaughan collected from it a total of 

35 species. It is characterized by large 

specimens of Ostrea sellaefonnis... . . . . . . . . . . 6 

1. Sanely and argillaceous marl,· not abundantly · 

fossiliferous; in layers differing considerably in co)or, hardness, and chemical composition. A number of analyses show calcium carbonate content ranging from 50 

to 90 per cent, but the actual local variation 

is even greater, for there are thin ledges of 

comparatively pure limestone and other beds 

of slightly ca.Icareous sand and clay. The 

color, as a whole, appears light gray, but individual beds ha.ve various shades of white, 

yellow, buff, gray, and greenish yellow. 

This bed is exposed as au almost vertical 

cliff, rising from water level, in which the 

harder layers form projecting ledges........ 50 

The 99-foot bench mark of the United 

States Army Engineers is situated near the 

ba.se of the bluff, and low-water level in the 

river is reported to be 87 feet above sea level. 

The preceding section starts approximately 90 

feet above sea level and extends to an altitude 

of 235 feet, with the base of the Barnwell at 

170 feet. 

On Savannah River downstream from Shell 

Bluff marl of the McBean for1nation is exposed 

28288 °-·19--5 

at Demerie's Ferry, Hancock Landing, Utley 

Point, and Blue Bluff and finally passes 

beneath water level at Griffin's Landing, where 

it is overlain unconformably by the Ostrea 

georgiana zone and calcareous fuller's earth. 

UNDIFFERENTIATED CLAIBORNE DEPOSITS. 

Fort Gaines .-A c01nplete section of the 

Wilcox and Claiborne formations is exposed in 

a high bluff along the Georgia side of Chattahoochee River at Fort Gaines and in the slopes 

from the terrace on which the town is built up 

to the level of the upland plain. The sections 

given below show the character of the Claiborne 

in this vicinity. 

Section along road leading eastfrom the·Raym,ur Hotel, Fort 

Gaines. 

L'l'hicknesses approximate. Measured by L. '\V. Stephenson,'t with com· 

ments by H. K. Shearer.) 

Age unknown: Feet. 

8. Coarse red ferruginous pebtJly sand. (Similar 

material extends down the hill for some distance, probably creep.) Thickness to top 

of hill, half a mile from the liotel........... 50 

Eocene: Undifferentiated Claiborne: 

7. Greenish sanely clays and argillaceous sands, 

more or less weathered and mottled......... . 40 

6. Compact fine greenish-gray sa.ndstone, with 

fossil prints (fossils collected)............... 3 

5. Pale-green fine loose sand ............... ,.... 3 

4. Compact fine greenish-gray sandstone, with 

fossil prints (fossils collected)............... 3 

3. Light-green compact, finely arenaceous clay. 

A part of the bed is indurated, breaks with 

hackly fracture, and resembles the silicified 

fuller's earth of eastern Georgia ................ 7 

2. Fine green sandstone........................ ~ 

1. Greenish clays and sands, more or less weathered and mottled. . . . . . . . . . . . . . . . . . . . . . . . . . 65 

175 

The following fossil mollusks fr01n beds 4 

and 6 were identified by T. W. Vaughan: 

Plejona sp. 

Turritella sp. 

Leda pharcida Dall? 

V enericardia planicosta Lamarck. 

.Miltha claibornensis (Conrad). 

Cytherea sp. 

Solen lisbonensis Aldrich? 

The preceding section starts at an altitude 

of 225 feet above sea level, 15 feet below the 

level of the business section of Fort Gaines, 

which is on the second (upper) river terrace. 

The following section is exposed in the bluff a 

quarter of a mile below the wagon bridge and 

1 Georgia.Geol. Survey Bull. 26, p. 263,1911. 
62 SHORTER CONTRIBUT10NS TO GENERAL GEOLOGY, '1918. 

has its top at the edge of the terrace, at an altitude of 215 feet above sea level. 

Section of bluff at Fort Gaines. 

(Measured by Otto Veatch; descriptions revised by H. K. Shearer.) 

Pleistocene : 

9. Coarse red sand with pebbles in the Feet. 

lower half; caps the bluff........... 15 

Eocene: 

Q 

Undifferentiated Claiborne: 

8. Drab fine-grained laminated clay with 

sand partings; has the appearance 

of fuller's earth but is not nearly so 

light and porous as the Twiggs clay, 

of Jackson age, and apparently has . 

a more kaolinic base. . . . . . . . . . . . . . . 8 

7. Yellow and grayish glauconitic sand. 

Locally it is oxidized and contains 

limonite-cemented crusts .......... 10-12 

6. Clay and sand, in part calcareous; 

consists of drab carbonaceous clay 

at base, sand in middle, and very 

sandy shell marl at the top ....... . 

5. Indurated clay layer or drab claystone; contains fossils and is similar 

lithologically to the claystone east of 

the town of Fort Gaines. (See preceding section)...... . . . . . ........ . 

4. Grayish argillaceous sand ........... . 

3. Yellowish and gray quartz sand; contains calcareous sand nodules; 

small pebbles noted at the base; 

fossils X enophora, Venericardia 

planicosta . ....................... . 

Unconformity(?). 

Wilcox formation: 

2. Clay, in part carbonaceous; calcareous, and lignitic sand, etc ...... . 

Unconformity. 

Midway formation: 

1. Impure limestone, maximum ....... . 

20 

2-2.5 

6 

2-2.5 

39 

20 

124 

In this section the Claiborne beds occupy the 

interval from 150 to 200 feet above sea level, 

and in the preceding section they extend from 

225 to 350 feet, indicating a total thickness of 

200 feet, only 25 feet of which is concealed. 

Tht3 top of the Claiborne has not been accurately located at this place, but on the Edison 

road, half a mile southeast of Fort Gaines, the 

Claiborne is overlain unconformably .by sand 

interbedded with purple and white mottled 

plastic clay at an altitude of 355 feet above sea 

level. 

The Claiborne strata are exceedingly variable 

in composition in the vicinity of Fort Gaines, 

and their lithologic appearance' at the town is 

completely unlike that a mile away. This 

difference is shown at a locality on the Lower 

River Road, three-quarters of a mile south of· 

Fort Gaines, where there is an exposure of 85 

feet of drab clay which is in part massive and 

sandy, in part interlaminated with sand, and 

is not fossiliferous. The clay crops out between 180 and 265. feet above sea level and is 

thought to be of Claiborne age. 

Cuthbert.-In the cuts on the Central of 

Georgia Railway west of Cuthbert two unconformities, believed to mark the top and bottom 

of the Claiborne, are exposed. The lower unconformity, at an altitude of 410 feet above sea 

level, is seen near the 121-mile post, 3 miles 

west of Cuthbert. 

Section 3 miles west of Cuthbert, near 121-mile post, Central 

of Georgia Railway. 

Undifferentiated Claiborne: Feet. 

5. Dark-red argillaceous sand with a few clay 

laminae.................................. 14 

4. Fine gravel.................................. 1 

Unconformity. 

Wilcox formation: 

3. Light-colored argillaceous sand, with laminae 

and beds 2 or 3 feet thick of clay like fuller's 

earth .................... •.· ..... -~........ l.o 

2. Red argillaceous sand, with clay laminae..... 30 

1. Blue and gray banded clay, with some sand 

laminae, dense, approaching kaolin rather 

than fuller's ea~th in properties. . . . . . . . . . . . 30 

85 

A second unconformity is exposed 1 mile 

farther east, in the cut near th~ 120-mile post, 

at an altitude of 460 feet. 

Section 2 miles west of Cuthbert, near 120-mile post, Central 

of Georgia Railway. 

Oligocene: Undifferentiated Vicksburg: 

2. Yellow plastic clay, partly laminated but with 

bedding much distorted by slump. Distributed through the clay are boulders and 

irregular masses of chert, containing fossils, 

most of which are undeterminable, but the 

Vicksburg species Pecten poulsoni was 

recognized. . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . 10+ 

Unconformity. (The unconformity is very irregular 

within a vertical range of 5 feet and is 

marked locally by a layer of ferruginous 

sandstone 1 to 2 inches thick, or by a thin 

ban4 of carbonaceous sand or clay.) 

Eocene: Undifferentiated Claiborne: 

1. Brown to yellow and red sand, a glauconitic 

sand more or less weathered, with local 

masses cemented by limonite............. 5+ 

Exposures between the two cuts show that 

the entire 50 feet of beds of the Claiborne consist of red sand, with only a few laminae of clay. 
DEPOSITS OF CLAIBORNE AND JACI\:SON AGE IN GEORGIA. .63 

. BARNWELL FORMATION. 

BURKE COUNTY. 

The Barnwell formation in Burke County 

consists of calcareous clay and shell marl 

overlain by red sand oontaining ledges of 

fossiliferous chert. The Ostrea georgiana zone, 

·which is characteristically developed at Shell 

Bluff (see pp. 60-61) and other localities on 

Savannah River, has been recognized also at 

several places in the interior. At Keys Mill, 

on Brushy Creek, in the northwest corner of 

Burke County, 3 miles northwest of St. Clair, a 

bed of Ostrea georgiana similar to that at Shell 

Bluff and apparently occurring at the same 

stratigraphic horizon is exposed ih an excavation near the mill dam. The section at this 

locality follows. . 

Sect·ion at Keys ~Mill. 

Barnwell formation: Feet. 

5. Reel argillaceous sand containing laminae of 

yellow plastic clay near the base and quartz 

gravel beds and a few fragments of chert 

near the top.............................. 40 

4. Coarse yellow sand, carbonaceous at the base.. 10 

3. Pale-green, somewhat calcareous hackly clay 

or fuller's earth containing thin beds and 

irregular pockets of sand. The contact with 

the oyster bed is sharp. . . . . . . . . . . . . . . . . . . . 8 

2. Lru·ge shells of Ostrea georgiana in a matrix of 

hard white limestone w1th patches of greenporous to dense and vitreous red flint containing numerous poorly preserved foasils (Turritella, Periarchus, etc.). The bed is at least 

15 feet thick. 

Other notable outcrops of chert were found 

at the following localities: W aynesboro-~iillen 

road 1 mile south of Waynesboro, altitude 260 

feet above sea level; Waynesboro-St. Clair road 

10 miles west of Waynesboro, altitude 335 

feet, ledge 5 feet thick; Waynesboro-Hephzibah 

road 3.1 miles northwest of Waynesboro, altitude 285 feet, 1 foot of vitreoua chert overlying 

5 feet of porous chert; Girard-Millhaven road 

2.1 miles southeast of Girard, altitude 220 ( ~) 

feet; Girard-Millhaven road 7.3 miles southeast 

of Girard, altitude 220 ( ~) feet, fragments of 

white vitreous flint. ' 

Chert beds exposed at Johnsons Landing 

and Stony Bluff on Savannah River in or opposite Screven County, along the lower course of 

Brier Creek below Girard, and at the former 

site of Millhaven on Beaverdam Creek were 

mapped as Vicksburg in the Coastal Plain 

report but without very strong paleontoloO'ic . b 

evidence. Vaughan 1 later suggested that the 

rock at Johnsons Landing may be of Jackson 

age and stated that it contains Pecten perplanus, which is now considered diagnostic of 

the Jackson.· 

ish clay. A few incrusting Bryozoa were 

found; other fossils are present but not determinable. Similar material is reported to 

extend to a depth of 70 feet. Thickness 

seen ..................................... . 

Recent investigations indicate that the main 

chert beds at all the localities cited are probably 

at the same geologic horizon a.c:; those exposed 

7 throughout Burke and Jefferson counties1. Concealed interval to level of the mill pond that is, near the top of the Barnwell forma-

(altitude 300 (?) feet above sea level) ..... . 

70 

5 tion-but chert of later age may be present at 

some of them. The upper surface of the 

Barnwell therefore dips below water level in 

Savannah River between Stony Bluff and the 

mouth of Brier Creek, in Screven County. 

Outcrops of chert beds are abundant throughout Burke County. They range in altitude 

from about 300 feet above sea level in the 

northern part of the county, where they are 

found near the hilltops, to 200 feet or less in 

the stream beds of the southern part. . Nearly 

all the chert appears to lie at practically the 

same horizon (near the top of the Barnwell) 

and may be residual from one thin but persistent bed of limestone. · 

The thickest and most extensive exposures 

arc in bluffs along Rocky Creek (altitude about 

280 feet above sea level) near the Louisville 

road, 3.3 miles southwest of Waynesboro. The 

slope up to 20 feet above water level in Rocky 

Creek is covered with great blocks of soft and 

RICHMOND COUNTY. 

The Barnwell formation caps the hills north 

of McBean Creek, where it over1ies the McBean 

formation, but in the absence of characteristic 

beds it is almost impossible to distinguish one 

formation from the other. In the vicinity of 

Bath and in the western part of the county the 

Barnwell contains at its base beds of indurated 

fuller's earth which directly overlie the Cr~­

taceous. A long, narrow area of Barnwell beds 

caps the ridge between Butler and Spirit creeks 

1 U. S. Gebl. Survey Prof. Paper 71, p. 739, 1912. 
64 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

and extends northwestward into Columbia 

County, where it overlaps the Lower Cretaceous beds to the edge of the crystalline area. 

As fossils are very rare in all the formations 

of Richmond County, the mapping of the contacts must depend largely on lithology and 

topography. 

A good section of the lower beds of the Barnwell formation is exposed near a spring on the 

north slope of Mount Enon, an isolated remnant of the original plain, near the Dean's 

Bridge road, 14 miles southwest of Augusta 

and about 3 miles northeast of Bath. 

Eocene: 

Section on north slope of .Mount Enon. 

Feet. 

Barnwell formation: 

8. Apparently all red sand to top of hill. 

Near the top are fragments of dense 

banded cherty sandstone ... c......... 60 

Twiggs clay member: 

7. Soft whi.te fuller's earth; as the top of 

the bed is not exposed, the thickness 

are very interesting and important. The 

McBean formation ia absent, and probably it 

never extended so far north. The calcareous 

beds found in the Barnwell farther south and 

west are here lacking, an"d the formation consists of beds of fuller's earth, clay shale, or 

lignite, lying directly above the Lower Cretaceous and overlain by red sand. An unconformity between the clay member and the 

red sand was noted at several places and may 

be of general occurrence throughout the 

county, and there are indications of local unconformities within the red sand. As the beds 

are aU of shallow-water origin, these unconformities may have been produced by very 

slight oscillations in the level of the land or by 

currents. 

Phinizy Gully.-The relations of the Barnwell strata to the Lower Cretaceous are well 

shown in a gully in the abandoned Augus.taWrightsboro public road, 1 mile northeast of 

may be greater than .indicated ....... . 

6. Argillaceous sandstone wi.th abundant 

but poorly preserved fossils and 

rounded quartz pebbles an inch ln 

maximum·diameter .................. . 

3 Grovetown, on the Phinizy property. This 

locality is especially interesting because it 

furnished a large collection of Eocene plants, 

1 described py Berry/ and because the uncon5. Coarse yellow sand .................. . 

4. Light-drab claystone, with angular 

and conchoidal fracture on weather11 formity between the Cretaceous and the Eocene 

is so well exposed here. 

ing. Has a high Sl0 2-Al20 3 ratio and 

is a silicified fuller's earth, exactly 

llke that at Hatcher's Mill and at 

Wrens, Jefferson County............. . 11 

3. Gray plastic clay..................... 1 

Unconformity. 

Lower Cretaceous: 

2. Indurated sandy kaolin, or flint clay. 10 

l. Kaoli.nic sand, etc., not measured. 

97 

The altitude of the top of the hill is about 

400 feet. 

At Bath about 25 feet of indurated fuller's 

earth is exposed irr the slope above the spring 

and bath house on the Walker property, and 

the bed is seen at several other places in the 

vicinity, but at Hepzibah, 6 miles farther east, 

the fuller's earth beds are absent. In the pit of 

the Albion Kaolin Co. the Cretaceous kaolin is 

overlain by 100 feet of red and yellow argillaceous sand without any conspicuous c~ay beds. 

COLUMBIA COUNTY. 

The only Eocene deposits of Columbia 

County are several lobes that extend into the 

southern part of the county near Grovetown, 

Forrest, and Harlem, but some of the exposures 

Section of Phinizy Gully, 1 mile northea't of Grovetown. 

Eocene: Foet. 

Barnwell formation: 

6. Yellow to red argillaceous sand, 

coarse and pebbly near base. C'aps 

hill to east of gully, to an altitude of 

540 feet ............................. 50+ 

5. Laminated plastic greenish clay.... 0-3 

4. Conglomerate of varicolored kaolin 

pellets in red sand. Contains some 

fragments of lignltized wood...... 0-2 

Unconformity(?). 

Twiggs clay member: 

3. Larninated shaly fuller's earth, containing leaf impressions. The bedding dips west at a smaller angle 

tha_n the unconformity below. 

Pinches out toward the east...... 0-6 

Lower Cretaceous: 

2. Silicified white sandy kaolin or flint 

clay; has. been described as" argillaceous sandstone." The bedding 

dips 10° E.; the unconformity 

above dips 15° W. in the head of 

the gully......................... 12 

1. Soft plastic white kaolin, interbedded with white and yellow sand, 

with some kaolin conglomerate 

near the bottom of the exposure. . 12 

1 Berry, E. W., U. S. f1eol. Survey Prof. Paper 84, pp. 130-131, 1914. 
DEPOSITS O:F CLAIBORNE AND JACKSON AGE IN GEORGIA. 65 

Gro'IH~town.-Fuller's earth exposed in the 

railroad cut at Grovetown station extends 4 

feet above track level and is overlain unconformably by red sand. The large cut south of 

the st-ation shows 20 feet of cross-bedded red 

and white sand, overlying the fuller's earth. 

The altitude of the station is 495 feet above 

sen, level, and the highest exposure of fuller's 

earth is at 500 feet. 

Fuller's earth was formerly mined on the 

Fiske property, about a quarter of a mile ea~t 

of the station. When visited in 1916 the pit 

was filled with water, but according to the section criven by Veatch and Stephenson 1 it pene- -

trnted 1.0 to 12 feet of fuller's earthJ whioh lay 

immedintely above white olay of Lower Cretaceous ago. The earth was not a com~ercial 

success for bleaching, probably because It contains a considerable amount of pyrite, which 

readily becomes oxidized to iron sulphate and 

sulphurous acid ~ter dryin~. . 

From this pit were obtained colleotwns of 

fossil plants, which have been studied and described by Berry. 2 

A well at Usry Bros.' gin, near Grovetown 

station, penetrated 12 feet of fuller's e~rth that 

is very massive and thick bedded ~n_d IS cut b_y 

several systems of widely spaced JOints. It Is 

dark gray when fresh and wet. but ?econles 

aln1ost white on drying and weathermg. It 

contains flakes of mica, small crystals of pyrite, and fragments of carbonized wood and 

sten1s. 

ChazJman lignite mine.-About 3 miles south 

of Grovetown a bed of lignite and lignitic clay 

occupies the horizon of the Twiggs clay. This 

material was formerly mined by W. C. Chapman for use as a fertilizer filler, but it was sufficion tly carbonaceous to be used as fuel under 

the boiler at the grinding plant. . 

Section in lignite pit 8 miles south of Grovetown. 

Barnwell formation: Feet. 

13. Gray or brownish incoherent sand, capping the hilL . . . . . . . . . . . . . . . . . . . . . 3-4 

12. Coarse red argillaceous sand, with a bed 

of fine gravel at the base............ 10 

Apparent unconformity. 

11. White, yellow, and red laminate'd plastic clay ........................ -.... 1-4 

10. Coarse angular yellow quartz sand; containslimonite fragments and in places 

fine graveL... . . . . . . . . . . . . . . . . . . . . . 1,5 

1 Op. oft., p. 269. s Berry, E. W., op. cit., pp. 129-163. 

Barnwell formation-Continued. Feet:-

9. Varicolored cross-bedded sand and fine 

. gravel, with some layers of white 

plastic clay a few inches thick. . . . . . 35 

8. White to buff or pink plastic clay, filling depressions in the surface of the 

lignite ............................. 0-1 

Unconformity. 

Twiggs clay member: 

7. Black lignite. . . . . . . . . . . . . . . . . . . . . . . . . 2-4 

6. Gray plastic clay. . . . . . . . . . . . . . . . . . . . . 1 

5. Black lignite......................... 1 

4 .. Gray clay, extremely plastic.......... 1 

3. Black lignite, containing large fragments of carbonized wood. . . . . . . . . . . 1 

2. Light-brown plastic lignitic clay....... l. 5 

1. Dark-broWn clayey lignite............. 1. 5 

75± 

JEFFERSON COUNTY. 

Nearly the whole of Jefferson County is underlain by the Barnwell formation, and its 

outcrop covers all of the county except a part 

near the northern boundary, where several 

streams have cut their valleys down into the 

Lower Cretaceous beds, and the area south of 

Louisville, where the hills are capped by beds 

of Miocene (Aluin Bluff) age or younger. 

The Twiggs clay member is thin but fairly 

persistent and appears in a line of exposures 

of fuller's earth across the northern part of the 

c~unty. In general, the fuller's earth of this 

county contains less iron and is· whiter than o 

the deposits farther west. Some of it is soft 

and very light and porous, but farther east a 

lai:ger proportion has become indurated into 

rather hard rock by the deposition of silica 

in the pores. Some of the silicified fuller's 

earth resembles the indurated Cretaceous kaolins found in the same area but may be 

distinguished from them on analysis by its 

much higher ratio of silica to alumina. Southward from the northern border of the Barnwell 

forn1ation the earth grades into calcareous clay, 

marl, and oyster-shell beds, which have few of 

the characteristics of a true fuller's earth. 

The upper part of the Barnwell forn1ation 

is made up of a considerable but w1measured 

thickness of red sand containing thin beds of 

plastio clay, locally indurated layers of fossiliferous or barren sandstone and thin beds of 

fossiliferous flint residual from original lenses 

of impure limestone. . 

Louisville.-One of the best sections of the 

upper part of the Barnwell formation is ex0 
66 SHORTER CONTRIBUTIONS-TO GENERAL GEOLOGY, 1918. 

posed in a gully on the east slope of Rocky 

Comfort Creek, about 300 yards above the 

wagon bridge three-quarters of a mile west of 

Louisville. 

Section three-quarters of a mile west of Louisville. 

Barnwell formation: Feet. 

8. Massive brilliant-red argillaceous sand..... 10+ 

7. Fine white silica or tripoli1 probably a decomposed chert bed ..................... 1-2 

6. Indurated yellow sand...................... 6 

5. Bluish and yellow mottled clay, laminated 

but rather plastic, intermediate in properties between fuller's earth and common 

pipe clay.......... . . . . . . . . . . . . . . . . . . . . . 3 

4. Coarse gray sand with a little clay, partly 

concealed................................ 14~ 

3. Gray sand and yellow clay, locally indurated. 2 

2. Concealed intervaL..... . . . . . . . . . . . . . . . . . . . 15 

1. Blue calcareous fossiliferous argillaceous 

sand, weathering yellow; from creek (215 

feet above sea level)... . . . . . . . . . . . . . . . . . 5 

57' 

As the red· sand bed, No. 8, continues to the 

level of Louisville Court House (315 feet above 

sea level), the total thickness is 100 feet. 

A bed of Ostrea georgiana shells in a matrix of 

calcareous clay resembling fuller's earth is exposed at low water in the south bank of Ogeechee River, 200 yards upstream from Cowart:S 

Bridge, 2.6 miles south of Louisville. The 

c bed is entirely similar to those at Danville, 

Twiggs County, and at Shell Bluff. Its 

altitude is a few feet below the base of the section on Rocky Comfort Creek. 

At Warren's Mill, on Big Creek 3 miles eastnortheast of Louisville, a bed of rock contain~ 

ing Ostrea georgiana was excavated for use in 

building a dani. There are no natural exposures of the oyster bed, but above water 

level in the creek (altitude 245 feet above sea 

level) is exposed 3 feet of blue calcareous 

fuller's earth, which dries and weathers white. 

This grades upward, by interbedding, into 

yellow argillaceous sand containing laminae of 

fuller's earth and fragments of oyster shells. 

Old Town.-At Old ,Town Plantation, 8.4 

miles by road southeast of Louisville, a bed of 

rotten fossiliferous chert in the red sand is exposed on the slopes up to 20 feet above the 

level of a small creek (altitude between 220 and 

250 feet). Collections of fossils made by S. W. 

McCallie, Earle Sloan, and T. W. Vaughan were 

identified by Vaughan, who supplied the following .list of fossils for the Coastal Plain 

report: 1 

Mortonia sp. 

Caricella pyruloides Conrad. 

Turritella carinata Lea. 

Mesalia vetusta (Conrad). 

Calyptraea aperta (Solander). 

Glycymeris staminea (Conrad). 

Glycymeris idonea (Conrad). 

Glycymeris n. sp. 

Crassatellites protextus var. lepidus Dall. 

Crassatellites n. sp. 

Venericardia alticostata Conrad. 

Cytherea perovata Conrad. 

Spisula praetenuis (Conrad). 

Corbula densata Conrad. 

Lunulites distans Lonsdale. 

More recent collections.furnished the species 

in the following list: 

Station 7428. Old Town road, east side of Boiling Spring 

Creek. J. E. Brantly, collector, 1915. 

Mortonella quinquefaria (Say)? 

Plejona petrosa (Conrad)? 

Turritella carinata Lea. 

Mesalia vetusta (Conrad). 

Glycymeris staminea (Conrad). 

Venus? sp. 

Cytherea perovata Conrad. 

Crassatellites protextus (Conrad) var. 

Protocardia sp. 

Diplodonta aff. D. ungulina (Conrad), very close to 

species in basal Jackson at Sims, Miss. 

Wrens.-Fuller's earth is exposed at anumber of localities in the vicinity of Wrens and 

has been cut by many wells in and around the 

village. The earth is almost white, nonplastic, and noncalcareous and shows various 

degrees of induration. A section is exposed 

on the north slope of Brushy Creek, on the 

Louisville road 1 mile south of Wrens. 

Section 1 mile south of Wrens. 

Barnwell formation: Feet. 

4. Yellow sand with interlaminated clay 1 

conformable with the underlying fuller's earth............................ 20 

Twiggs clay member: 

3. Slightly indurated fuller's earth, porous, 

laminated, greenish when wet but becoming pure white on drying. Contains laminae and beds of greenish sand 

as much as several feet thick........... 20 

2. Light-greenish argillaceous sand, slightly 

indurated.............................. 5 

1. Concealed interval from creek level. . . . . . 5 

50 

1 Georgia Geol. Survey Bull. 26, p. 292, 1911. 
DEPOSITS OF CLAIBORNE AND .JACKSON AGE IN GEORGIA. 

The section extends from 360 to 410 feet 

above sea level, and 410 feet is also the altitude 

of Wrens station. 

Indurated fulfer's earth.unconformably overlies the Cretaceous at an altitude of 325 feet 

above sea level at Hatcher's Mill, on Reedy 

Creek 5.2 miles north of Wrens; and at Patterson's Bridge, on Brier Creek 7. 7 miles northeast of Wrens, is an exposure of sandy laminated 

fuller's earth, a part of which is indurated and 

resembles that at Hatcher's Mill. 

GLASCOCK COUNTY. 

The unconformity separating the Lower Cretaceous from the Barnwell formation is plainly 

shown on the Gibson-Mitchell road at Jumpirig 

Gully Creek, 2 miles west of Gibson. The 

section at this locality was given by Veatch 

and Stephenson 1 and ne~d not be repeated 

here. All the strata above the CretaceousEocene unconformity, which lies at an altitude 

of 410 feet, should be referred to the Barnwell 

formation. 

An. interesting section, which shows the 

variability of the basal beds of the Barnwell, 

is exposed in the pits of the Harbison & Walker 

Refractories Co., east of milepost 48 on the 

Augusta Southern Railroad, 2 ·miles east of 

Gibson. The· pits are. in the eastern escarpment of Rocky Comfort Creek. 

s~ction in ~re-clay mine 2 miles east of Gibson. 

Eocene: 

Section at Rocky Comfort Creek 1 .. i miles north· of Gibson. 

Eocene: 

BarnwE'll formation: Feet. 

9. Massive red sand to top of hill .......... 45 

8. Interbedded red sand and red and gray 

plastic clay. . . . . . . . . . . . . . . . . . . . . . . . . 10 

7. Mottled argillaceous sand, without kaolin 

fragments ........................... 20 

6. Mottled argillaceous sand, with small angular fragments of indurated kaolin... 7 

5. Fine gravel, with angular fragments of 

indurated kaolin........ . . . . . . . . . . . . . 1 

4. Limonite-cemented sandstpne.......... . 1 

Unconformity. 

Lower Cretaceous: 

3. Yellow, white, and mottled kaolinic sand 5 

·2. Concealed intervaL ......... : ......... 50 

Pre-Cambrian(?): . 

1. Granite....... . . . . . . . . . . . . . . . . . . . . . . . . . 20 

158. 1 

The altitude of this section. is 355 to 515 

feet above sea level, and the Cretaceous beds 

occupy only the interval from 375 to 430 feet. 

The granite mass outcropping to 20 feet above 

the level of the creek is prohably a hill or monadnock in the pre-Cretaceous surface, as no 

more igneous rock is seen for some miles farther 

north. 

Other localities in Glascock County, with the· 

fossils obtained at them, have been discussed 

on pages 46-4 7. 

WASHINGTON COUNTY. 

Barnwell formation: 

4.. Yellowish sand with few pebbles ..... . 

The Barnwell formation is present throughout a large part of Washington County. The 

Fcc~ bed within the formation most easily recognized by its lithology is the fuller's earth of the 3. Conglomerate of yellow sand and pebbles; where bed 2 is absent, this bed 

rests directly upon the Cretaceous... . 0-6 

2. Gray to yellow indurated laminated clay 

or shale, with leaf impressions; at the 

base is a patch of impure lignite which 

grades upward into the gray plastic 

clay; fills erosion hollows in the surface of the Cretaceous. . . . . . . . . . . . . . ()-4 

Unconformity (altitude 340 feet above sea level). 

Lower Cretaceous: 

1. Gray fire clay and indurated kaolin, not 

very hard but extremely brittle...... 10-15 

On the Gibson-Warrenton road 1.4 miles 

north of Gibson is exposed a section of the 

entire Cretaceous and lower part of the Eocene. 

There are no fossil.-bearing beds, but the section is typical of deposition near the shore line. 

1 Op. cit., p. 273. 

Twiggs clay member, which, although discontinuous and variable in thickness, can be traced 

by a line of outcrops from Oconee across the 

county to Chalker. The beds underlying the 

fuller's earth average about 50 feet in thickness 

and consis.t chiefly of calcareous clay and sand, 

with locally indurated beds of quartzite containing a characteristic lower Jackson fauna. 

Above the Twiggs clay member is red sand, 

with lenses of impure limes~one containing 

Mortonella quinquefaria (Say), which probably 

represent the chert zones of Jefferson and 

Burke counties. The exposures of limestone 

extend from Wring Jaw Landing, on Oconee 

River a short distance south of the .Washington 

County line, to Sunhill, passing between Sandersville and Tennille, and outliers of the same 
.68 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

rock are thought to occur 2i miles south o£ 

Warthen, but details are not available. 

Bujf'alo Creek.-The Barnwell formation is 

well exposed in the steep escarpment east of 

Buffalo Creek, and sections have been measured 

along the roads east of Sheppard's Bridge, 

which is 3 miles north of the mouth of the creek 

and east of Turnpike Bridge, 5 miles farther 

north. 

Section along road east of Sheppard's Bridge, 1! miles north 

of Oconee. 

Eocene: 

Barnwell formation: Feet. 

9. Red sand with plastic clay, laminated 

toward base .................. '? • • • • 70 

Twiggs clay member: 

8. Plast.lc laminated yellowish-green clay 12 

7. Light-yellow nonplastic porous fuller's 

earth............................. 5 

6. Gray plastic clay, more or less sandy. 14 

5. Massive gray argillaceous sand, with 

casts of fossils, Pecten perplamu;, 

Panope, GlycymP.ris............... 6! 

4. Interbedded sand and fuller's earth.. 7! 

3. Gray, very plastic sandy clay, becoming more sandy toward the top. 

The upper portion contains Flabelbnn and other poorly preserved fossils .............................. 27 

2. Gray sand, mottled with red; at base 

contains quartz pebbles as much as 

1! inches long; day laminae near 

the top ........................ · . . 6 

Lower Cretaceous: 

1. Cross-bedded kaolinic sand from level 

of Buffalo Creek. This may include 

the basal beds of the Eocene, as the 

contact has not been exactly determined .......... , ............ ' .... 70 

218 

The altitude of the: base of bed 2 of the preceding section is about 285 feet above sea level. 

Section along road east of Turnpike Bridge. 

Eocene: 

Barnwell formation: Feet. 

Eocene-Continued. 

Barnwell formation-Continued. Feet. 

Twiggs clay member-Continued. 

6. (]overed interval. Beds probably 'of 

same character as the next underlying stratum. A spring emerges 

near the top of the interval. . . . . . . . 20 

5. Dark-gray sandy clay....... . . . . . . . . . 5 

4. Greenish, slightly pl~tic clay, resembling fuller's earth in appearance, 

containi'ng considerable sand and 

a few fossils . . . . . . . . . . . . . . . . . . . . . . 25 

3. Sandy and calcareous clay, containing 

Flabellum.......... . . . . . . . . . . . . . . . 3 

2. Gray sandy clay at base, grading upward into blue or greenish, very 

plastic gumbo or pipe clay.... . . . . . 12 

Unconformity (altitude 300 feet above sea le,~el). 

Lower Cretaceous: 

1. Light-colored sand containing lenses 

of white kaolin, from level of Buffalo Creek. . . . . . . . . . . . . . . . . . . . . . . . 70 

220 

Sandersville.-Near the Little Keg Greek 

bridge, 7.2 miles by road northwest of Sandersville and 8 miles in an air line northeast of 

Turnpike Bridge (see section and discussion, 

p. 48), the fuller's-earth bed is not present, but 

it comes in again farther south and is exposed 

where the same road crosses Rocky Branch, 

3.2 miles by road northwest of Sandersville. 

Section along public road south of Rocky Branch, 3.2 miles 

northwest of Sanders11ille. 

Barnwell formation: Feet. 

. 6. Massive red sand to top of. hill. . . . . . .. . . . . . 90 

5. Gray and yellow argillaceous sand........ 12 

Twiggs clay member: 

4. Greenish fuller's earth, containing a few 

laminae of sand. . . . . . . . . . . . . . . . . . . . . . . 10 

3. Red sand with laminae and thin beds of 

greenish fuller's earth............. . . . . . 10 

2. Gray and greenish clay,· becoming sandy 

and fosslliferons toward the top ... ·. . . . . 7 

1. Concealed interval from level of Rocky 

Branch.·.............................. 5 

134 

9. Red sand........................... 35 As the base of this section is at an altitude 

of 330 feet, it can not be far above the top of 

10 the Cretaceous. 

Twiggs clay member: 

8. Greenish plastic laminated sandy clay 

7. Fuller's earth. The exposures are not 

quite continuous, and there may be 

interbedded sandy strata in the 

covered intervals. All the earth in 

sight, however, appears to be of sufficient purity for use as a bleaching 

earth. · It is light greenish yellow, 

fine grained, nonplastic, noncalcareous, and somewhat iron stained on 

account of its proximity to the surface but contains very little sand ... 

Limestone referred to the upper part of the 

Bl).rnwell formation is exposed at the spring 

and lime sink at "the head of Limestone Creek, 

1 mile south of the; courthouse at Sandersville. 

The topographic relations of the exposures are 

well shown in the sketch map by Brantly. 1 

The section is as follows: 

1 Brantly, J. E., Limestones and marls of the Coastal Plain of Georgia. 

40 'Georgia Geol. Survey Bull. 21, p. 59, 1916. 
0 

DEPOSITS OF CLAIBORNE AND ;r ACKSON AGE IN GEORGIA. 69 

Section 1 mile south of Sanders·ville. J the presence of outliers of this bed several 

Barnwell formation: Feet. miles north of the exposures described. 

6. Red sand to top of hilL .................... 10± l·Varthen.-A good exposure of the Twiggs 

5. Coarse gray sandstone, irregularly indurated clay member of the Barnwell formation is 

and terminating laterally in red sand...... 6 f d 

4. Grn.y sand, oxidized red and yellow, exposed oun on the property of A. J. Irwin, 3 miles 

along road ............................... 15 south of W m'then and 6 miles north of Sanders3. Light-gray chalky limeston..,; contains M"or- ville, at the head of a branch of Little Keg 

tonella quinquefaria (Say) in abundance Creek. 

and casts of other fossils; Ostrea georgiana 

is reported here. 1 Exposed in sink. . . . . . . . 12 

2. Gray, very sandy limestone with obscure 

fossils................................... 5± 

1. Bright-blue incoherent sand, apparently 

grading latera.lly into gray sandy limestone. 

Exposed in streain below sink ....... .' . . . . . 2 

The altitude of the base of the exposure is 

400 feet, which must be approxima~ely 100 

feet above the top of the Cretaceous and stratigraphically higher than the calcareous fuller's 

earth and limestone beds found in a well near 

Limestone Church, 3 miles down the creek. 

The yellowish and mottled sands that cap the 

hills within a mile south of this exposure probably belong to the Alum Bluff· formation, 

which overlaps the beds of Vicksburg age. 

SunhiZZ.-Limestone of the same horizon as 

that exposed at Sandersville was formerly 

used in the manufacture of lime at Sunhill. 

The old kiln and quarry are on the south slope 

of Williamson's Swamp Creek, an eighth of a 

mile southeast of the station. Brantly 2 gives 

the following section: 

Section in old quarry at Sunhill. 0 • Feet. 

Section on Irwin property, 3 miles south of Warthen. 

Barnwell formation: Feet. 

5. Massive red sand. This be~. overlies the 

clay with a sharp contact, showing no 

sib'll of gradation, which may represent 

a local unconformity.. .. .. . . . . . . .. .. . . 40 

Twiggs clay member: 

4. Greenish plastic clay and indurated 

sandy clay.............................. 2 

3. Good fuller's earth, brownish gray when 

dry, laminated, brittle, and free from 

grit ............. ·...................... 8 

2. Plastic greenish clay, with a tendency to 

crumble on drying... . . . . . . . . . . . . . . . . . 15 

1. Greenish sandy, nonplastic clay resembling fuller's earth, containing thin 

beds of sand and plastic clay........ . . . . 20 

85 

This section extends from 365 to 450 feet 

above sea level, with the top of the clay member at 410 feet. The normal qip of the beds 

would carry the clay well below the limestone 

exposures at Sandersville and Sunhill. 

On the property of John and George Powell, 

1 

about 1 mile north of the locality on the Irwin 

property just described, are outcrops of a bed 

of white to dark-brown cherty sandstone containing small masses and veinlets of iridescent 

6. Red argillaceous sand............................ 10 

L Medium-grained white sand grading into yellow 

5 opal, some of which are said to be large enough 

2 to cut as gems. Much fragmental material 

: from this bed is scattered in the vicinity of the 

sand .......................................... . 

3. ·white calcareous clay .......................... . 

2. AronaceouA limestone or calcareous sandstone .... . 

1. Hard white com pact, partly crystalline limestone. outcrops. The chert contains silicified fragments of echinoids, but determinable fossils 

are rare. 

29 

As the altitude of the base of· this section is 

355 feet above sea level and as the normal dip 

of the beds is about 10 feet to the mile toward 

the southeast, the lim~stone must lie at about 

the sa.me horizon as that at Sandersville. 

Speci1nens of Mortonella quinquefaria (Say) 

in a n1atrix of limestone like that near Sandersville and Sunhill, collected by S. W. McCa.llie 

on the 'f. W. S1nith farm, 2! miles south of 

Warthen (U. S. G. S. station 3953), indicate 

t Veatch, Otto, ll!ld Stephenson, L. W ., Georgia Geol. Survey Bull. 26, 

p. 253, 1911. 

1 Op. cit., p. 61. 

The stratigraphic position of this chert bed 

is very near the base of the Barnwell. Beds of 

chert and sandstone at the base of the Barnwell 

are more extensively developed and more fossiliferous farther northeast, in the vicinity of 

Chalker and Gibson. 

Ohalker.-Near milepost. 65 on the Augusta 

Southern Railroad, 1 t miles southwest of 

Chalker, a lens of sandy kaolin of Lower Cretaceous age (used in the manUfacture of common pottery) is overlain unconformably by 6 

feet of bedded yellow to white clayey sand of 
70 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

Eocene age. A quarter of a mile southwest of 

the pottery pit about 10 feet of indurated 

fuller's earth is exposed above the railroad level, 

overlain by a thin bed of quartzite, ·and below the railroad level and just above the Cretaceous is a bed of hard fossiliferous sandstone. 

The following· species were obtai~~d at this· 

locality: 

Station 7708. Base of Barnwell formation, Augusta Southern Railroad, H miles southwest of Chalker, Washington 

County, Ga., Cooke and Shearer, collectors, 1916. 

Mesalia vetusta Conrad. 

Turritella carinata Lea. 

Cerithit1m sp. 

Glycymeris staminea (Conrad). 

Mytilus texanus (Gabb ). 

Corbula alabamiensis Lea. 

Meretrix sp. 

V enericardia sp. 

To these . should be added Flabellum. cuneiforme Lonsdale, Barbatia cuculloides (Conrad), 

and Ostrea georgiana Conrad~ (identified by T. 

W. Vaughan1), which were collected by S. W. 

McCallie at the same locality (station 3945). 

One mile south of Chalker, where the road 

to SandersviUe ascends from the Ogeechee 

Valley to the upland plain, a section is exposed 

which carries no fossiliferous beds but shows 

well the character of the Barnwell formation. 

Section along Sandersville road 1 mile south of Chalker. 

Eocene: 

Barnwell formation: Feet. 

10. Massive· red and mottled ·sand to top 

of hill.......................... 30 

The Cretaceous surf ace in ·this area, as well 

as in the counties farther east, is much more 

irregular than to the west, showing a drop of 

no less than 50 feet between this exposure (altitude about 385 feet) and the vicinity of the 

sandstone exposures not more than a mile 

away. 

WILKINSON COUNTY. 

The upland areas of Wilkinson County are 

underlain by beds of Jackson age, but Oconee 

River and Commissioners and Big Sandy 

creeks h.ave cut their valleys down into the 

Lower Cretaceous strata.. The Barnwell strata 

cover the southern part of the county and form 

a narrow lobe along the ridge between Big 

Sandy and Commissioners creeks and an elongated erosional outlier between Commissioners 

Creek and Oconee River. Both of the latter 

areas extend beyond the northern boundary of 

the county. Chert of Vicksburg age is found 

along the southern county line, and it is possible, as in Twiggs County, that a part of the red 

sand farther north belongs to that formation. 

A gradual change in the character of the deposits of Jackson age from west to east is noticeable in the area between Ocmulgee and Oconee 

rivers. The Tivola tongue of the Ocala limestone is nearly 50 feet thick along the Ocmulgee, 

in Twiggs and Houston counties, but it pinches 

out before reaching the Oconee. In Wilkinson 

County it is thin and very impure and is absent 

at many localities. The largest exposure is on 

the property of the Generalo Bauxite Corporation near Toomsboro, but the bed there car~ 

ries only about 50 per cent of calcium carbonate,. 

the remainder being sand and clay. The limestone that is exposed on Oconee River at Wring 

9. Red sand with laminae of white and 

bright-purple clay. This coloring is characteristic of the Alum 

Bluff formation in the southern 

part of the State, but it is unlikely that that formation extends 

so far north ..................... . 

8. Yellow and mottled sand ........ : ... . 

Twiggs clay member: 

7. Greenish laminated fuller's earth, 

stained and somewhat plastic on 

account of weathering ............ . 

17 Jaw Landing, Johnson County,Z is correlated 

16 not with the bryozoan-bearing limestone of the 

southwestern part of the State but with the 

limes.tone beds at a higher Jackson horizon 

11 which are exposed near Sandersville. (See 

6. Coarse yellow sand ................ . 

5. Greenish laminated fuller's earth, 

free from sand ................... . 

4. Concealed interval.. ............... . 

3. Fuller's earth containing a little sand. 

2. Sand with laminae of fuller's earth .. 

Lower Cretaceous: 

1. White sand with kaolin lenses; to 

level of Chalker station ........... . 

1 'Georgia Geol. Survey Bull. 26, p. 276, 1911. 

11 pp. 68-69.) 0 

In Wilkinson County the Twiggs clay mem1 her is less persistent and less pure than in 

10 Twiggs County, and the material is generally 4 

4 too sandy or calcareous to serve as a commercial fuller's earth. Locally both limestone and 

fuller's earth are absent, and the Barnwell for55 mation consists entirely of red sand with a few 

159 thin beds of plastic clay or gumbo. 

2 Veatch, Otto, and Stephenson, L. W ., op. cit., p. 305. 
D19POSITS OF CLAIBORNE AND JACKSON AGE IN GEORGIA. 71 

Gordon.-A section typical of the beds in the 

northern part of the county is exposed in a pit 

of the Savannah Kaolin Co., 1 mile south of 

Gordon. 

Section in pit of Samnnah Kaolin Co. 

Eocene:· :Feot 

Barnwell formation (upper part): 

5. Red and mottled argillaceous sand 

to the top of the hill.............. 60 

'l~wiggs clay member: 

4. Greenish-yellow fuller's earth, conToomsboro.-ln the immediate vicinity of 

Toomsboro no limestone nor fuller's earth is 

exposed and ·the Barnwell seems to,) consist 

entirely of red sand, but the missing beds crop 

out on the property of the General Bauxite 

Corporation, 3 miles west of the station. No 

complete section is exposed. The following 

section is made up from aneroid readings taken 

at widely separated outcrops: 

tabling chalk nodules and a few Section on property of the General Bauxite Corporation, 

fossils ................ ··· .. ······· 10 3 ?niles west of Toomsboro. 

Ocala limestone (Tivola tongue): 

3. Sandy limestone, with Pecten perplantts and abundant bryozoa..... 4 

Barnwell formation (basal part): 

2. Argillaceous glauconitic sand filling 

erosion depressions in the Cretaceous surface.............. . . . . . . . . . 0-2 

Unconformity. 

Lower Cretaceous: 

1. Massive white kaolin.. ... . . . . . . . . . . . 30 

106 

Bed 3 of tllis section represents the tip of 

the Tivola tongue of the Ocala limestone. 

Big Sandy Valley.-ln the exposures along 

the Valley of Big Sandy Cree:k the Tivola tongue 

of limestone is genm:ally absent or is I,'epresented by local beds of fossiliferous chert, but 

the fu1ler's earth bed is well developed. A 

typical section is exposed along the public road 

on the southwest side of Big Sandy. Creek near 

Saud Bed Bridge, 3 miles south of Irwinton. 

S.cction ncar Sand Bed Bridge, on southwest side of Big Sandy 

• Creek. 

Eocene: 

Barnwell formation: Feet. 

G. Red, yellow, and mottled argillaceous 

sand, containing some thin beds of 

plastic clay ........................ · 40 

Twiggs clay member: 

5. Thin bed of sticky yello·wish clay, not 

well exposed ..... ,................ 5? 

4. Fuller's earth, containing a few partings of yellow sand not over 1 inch 

·thick, but the greater part of the interval is thick-bedded light-colored 

earth............................. 25 

3. Very plastic bluish clay; several feet 

exposed, but the top and bottom of 

the bed are concealed............. 5? 

2. At bottom red sand with laminae of 

clay resembling fuller's earth; 

above, mottled red and bluish 

clayey sand....... .. . .. . . .. .. .. . . . 25 

Unconformity. 

Lower Cretaceous: 

1. Massive white kaolin................ 15 

115 

Eocene: 

Barnwell formation: 

5. Red sands capping hills. 

Twiggs clay member: 

4. Calcareous fuller's earth ........ . 

Altitude 

in feet. 

300 

Ocala limestone (Tivola tongue): 

3. Hard and· soft yellow impure 

limestone (50 per cent CaC03), 

containing Pecten perplanus, 

Periarchus pileus-sinensis, and 

Bryozoa of the Rich Hill facies 

of the Jackson fauna .......... 270-290 

Unconformity : ......................... ·...... 250 

Lower Cretaceous: 

2. Bauxite lenses. 

1. Kaolin and kaolinic sands. 

BALDWIN COUNTY. 

So far as known, only one lobe of the Barnwell formation enters Baldwin County. The 

Barnwell material forms the overburden at 

the fire-clay pits of the Stevens Bros. Co.,· 

at Stevens Pottery; and in one of these pits 

the section given below was measured. 

Section in clay pit, S.tevcns Pottery. 

Eocene: 

Barnwell formation (Twiggs clay member): Feet. 

5. Soil, consisting of weathered fuller's earth· 

mixed with red sand. . . . . . . . . . . . . . . . . . 3 

4. Fuller's earth, sandy, iron-stained, of 

higher specific gravity than commercially valuable earth of Twiggs County 

but very similar to the latter in appearance and composition; contains casts of 

fossils. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 

3. Blue argillaceous marl; Bryozoa very 

abundant in lower part; Mollusca more 

abundant toward top .. :............... 10 

2. Light-g1·een glauconitic clayey sand filling 

minor irregularities in the Cretaceous 

surface; contains a few Bryozoa.. . . . . . . . 0-2 

Lower Cretaceous: 

1. Massive kaolin, locally sandy or bauxitic, 

used as fire clay........................ 20 

47 
72 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

Station 7755. Bed 3 of section at Stevens Pottery, Central 

of Georgia .Railway, Baldwin County, Ga. C. Wythe 

Cooke, collector, 1916. · 

Bryozoa. (Rich Hlll facies of Jackson fauna). 

Turritella cf. T. arenicola var. branneri Harris. 

Calyptraea sp. 

N ucula ovula Lea. 

Yoldia sp. 

Leda cf. L .. coelata Conrad. 

Leda albirupina Harris? 

Panope oblongata (Conrad)? 

Pecten perplanus Morton? 

Pseudamusium sp. 

Corbula oniscus var. ·(probably) wailesiana Dall. 

Phacoides (Miltha) claibornensis Conrad. 

Tellina sp. 

Tagelus? sp. 

Cytherea discoidalis Conrad? (also at Roberts). 

Venericardia planicosta (Lamarck). 

Venericardia sp. 

JONES COUNTY. 

Several small isolated areas of beds of Jackson . age extend in to the southern part of Jones 

County, locally overlapping the Lower· Cretaceous deposits and resting upon the crystalline 

basement rocks. 

Interesting exposures of fossiliferous beds 

occur in the cuts of the Georgia Railroad, 

near Roberts, 9.4 miles by rail northeast of 

Macon. The best section is shown in the cut 

1 mile northeast of the station, near the overhead crossing of the Central of Georgia Railway. 

Section in cut 1 mile northeast of Roberts. 1 

Eocene: 

Barnwell formation: Feet. 

6. Loose rod sand, containing a few 

scattered quartz pebbles; no fossils 

observed.......................... 10 

Twiggs clay member: 

5. Greenish and drab laminated sandy 

clay (fuller's earth), porous and of 

low, specific gravity............... 12 

4. Laminated sandy clay containing 

white chalk nodules and casts of 

fossils. The upper 2 feet of the bed 

is very fossiliferous. This bed i.~ a 

typical calcareous fuller's earth..... 8 

3. Bluish fossiliferous mud or marl....... 8 

Crystalline basement: 

2. Concealed a few feet .................. · ? 

1. Crystalline igneous rock. 

The igneous rock does not appear· in this 

cut but crops out in the next cut, a quarter of a 

mile farther northeast, where it is overlain by 

red sand. The highest altitude reached by the 

crystalline rock in this cut is 590 feet; the 

base of bed 3 in the section is 595 feet above 

sea level. 

I Adapted from Veatch, Otto, and Stephenson, L. W., op. cit., p. 280. 

The amount of overlap of the Barnwell beds 

on the crystalline rock at this point is not 

great, for in a cut less than a mile south of 

Roberts the red sand of JackSon age unconformably overlies gray micaceous kaolinic sand 

·of the Cretaceous. · 

Bed 3 closely resembles the corresponding 

stratum (No. 3) in the section at Stevens Pottery, and the sections are similar in other respects. 

The exposures near Roberts were first studied by Harris/ who referred the strata to 

the upper Wilcox ("Lignitic"). Preliminary 

study of collections of fossils made by McCallie, 

Sloan, and Vaughan led Vaughan3 to the conclusion that the beds are of lower Claiborne 

age. It appears, however, that the determinations of the most critical species were based 

on very imperfect material, and the correctness of some of them is open to question. The· 

list of species as here revised contains a number of species in common with the lower tTackson fauna of Arkansas and bears a close resemblance to that of the species occurring in 

the lower part of .the Barnwell formation near 

Gibson. This opinion of the age is in accordance with the lithologic and structural evidence, whichcshows that these beds are of the 

same age as the fuller's earth and bryozoanbearing limestone of Twiggs County. Therevised list of species follows: 

Fossils from cut on Georgia Railroad 1 mile east of Roberts, 

Jones County. 

[Identified by T. W. Vaughan; list revised by C. W.C~oko.) 

Collectecl by-

:McCallie. Sloan and 

Vaughan. 

Endopachys maclurii (Lea) ................... . X 

Cylichna sp ................... ,. . . . X 

Plejona petrosa (Conrad). . . . . . . . . . . . X X 

Clavelithes sp. . . . . . . . . . . . . . . . . . . . . . X ........ . Mazzalina sp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . X 

Levifusl!s branneri Harris? ............ 

1

......... X 

Pseudohva vetusta (Conrad)......... . . . . . . . . . X 

Turritella a pita De Greg. . . . . . . . . . . . . X ........ . TurriteJla sp. . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . X 

Turri tell a carinata Lea?. . . . . . . . . . . . . X ........ . Turritella arenicola Conrad .................. . Natica sp....... ...................... X 

Calyptraea aperta (Solander). . . . . . . . X 

Adeorbis sp ...................... ·... X 

N ucula ovula Lea..... . . . . . . . . . . . . . . X 

Yoldia aff. Y. psammotaeaDall.. ..... X 

Leda alhirupina Harris..... . . . . . . . . . X 

I,eda sp ..................................... . Trigonarca sp..... .. . . . . . . . . . . . . . . . . . X 

X 

X 

X 

X 

X 

X 

2 Harris, G. D., Eocene outcrops in central Georgia: Bull. Am. Paleon· 

tology, vol. 4, p. 4, 1902. 

a Georgia Geol. Survey Bull. 26, p. 282, 191L 
DEPOSITS OF CLAIBOR-NE AND JACKSON AGE IN GEORGIA. 73 

Fossils frorn cut on Georgia Railroad 1 rnile east of Roberts, extends less than an inch from the surface, 

Jones County-Continued. whereas in the northern part of the county the 

Collected by- material is oxidized to depths of many feet. 

Section in ft.tller 's-earth mine of the General Reduction Co. 

m.c "~~"" C ll' Sloanand l lf ·z J ·'P'k p k a 1e. Vaughan. ~a a rn~ e nort ~west o, ~ es ea . 

Glycymeris sp ............................... . Glycymeris trlgone1la (Conrad)? ..... -~ X 

Ostr?a a:Iabamiensis Lea ..................... . Ptena hrnula (Conrad) ....................... . Pecten. n. sp ................................ . 

Pe ~~ ~:a~~~~-~~~~~s!~~-~! _s_c_i ~1-t~l-I~~~~~. x 

X 

X 

X 

X 

X 

Modiolus alabamiensis Aldrich....... X · ........ . Periploma sp ................................ . Venericardia planicosta (Lamarck). . . X 

Protocardia, probably P. nicolleti 

(Conrad) .......................... --·-----· Phacoides (Miltha) claibornens.is 1 (Conrad) .. :....................... X 

Cytherea sp .................................. . Cvtherea discoidalis Conrad'? ................ . P8ammobia sp...................... X 

Spisula parihs (Conrad) or S. funera.ta (Conrad) ............................ .. Corbula onisr.us Conrad............... X 

Corbula alabamiensls Lea............. X 

TWIGGS COUNTY. 

X 

X 

X 

X 

X 

X 

X 

X 

X 

Vicinity of Pilces Peak.-The Twiggs clay 

member of the Barnwell attains its greatest 

thickness in Twiggs County, where, at Pikes 

Peak, it is mined for use as fuller's earth. The 

n1en1ber changes considerably in character 

fr01n north to south within the county. The 

best exposm·es in the northern part are on the 

property of the General Reduction Co., near 

Pikes Peak, where there are two well-defined 

beds of fuller's earth in an interval of about 100 

feet. The lower bed is about 45 'feet thick, the 

upper n1ore than 20 feet, and the ·two are separated by a bed of greenish-yellow fossiliferous 

sand which reaches a thickness of 30 feet. The 

earth in this vicinity is not calcareous, except 

nen.r the base, where it grades into lilnestone. 

Where leached and oxidized by surface water 

it has a pale-yellow to cream color and is extreJnely light and porous; but below the zone 

of oxidation it is usually dark gray and contains 

organic 1natter and pyrite. Farther south, 

in the neighborhood of Danville n.nd Westlake, 

for instance, the fuller's-earth bed becomes 

tbitmer as the underlying limestone thickens 

and the clay bep01nes more and more calcareous. 

The calcareous clay is blue or gray when unoxidized, but becomes cream-colored or yellow 

at the surfa.ce. As it is n1uch less pervious than 

the noncalcareous variety farther north, the 

zone of oxidation in many parts of its outcrop 

Barnwell formation(?): Feet. 

8. Massive dark-red sand.................. 17 

7. Fine quartz gravel, indistinctly bedded. 10 

6. Varicolored sands with thin layers and 

' fragments of sticky plastic "gumbo" 

clay. Some layers of the sand are slightly indurated. . . . . . . . . . . . . . . . . . . . . . . . . 8 

Unconf9rmity (?). 

Twiggs clay member: 

5. Light-colored fuller's earth. The lower 

. portion is thin bedded, with fine sandy 

partings stained by oxides of iron and 

manganese. Toward the top the earth 

becomes more massive, and the beds 

are several feet thick between partings. 

The whole mass of fuller's earth is cut 

by joints in various directions, and iron 

and manganese stains are found along 

the joint planes. Some of the joints 

and partings are. slickensided, showing 

that slight movements, probably caused 

by shrinkage, have occurred. This bed, 

which is uniform in texture and composition and is very light and porous, 

constitutes the commercially valuable 

fuller's earth .... ~ . . . . . . . . . . . . . . . . . . . . 17 

4. Dark-colored fuller's earth, almost black 

when wet but becoming light gray on 

drying. The dark color is probably due 

to organic matter. The clay contains 

visible crystals of pyrite and gives off 

a strong odor of sulphur dioxide when 

dried at 100° C. It also contains scattered concretions of hard siliceous material. The black layer thins to the north 

and west-that is, the slope of its upper 

surface follows the slope of the hill. The 

line of contact with the light-colored 

earth is sharp and even, but there is no 

visible change in texture, and the contact was observed to cut obliquely 

across the sand partings (bedding 

planes). It is evident that the light 

earth has been derived from the dark 

variety by leaching and oxidation of 

pyrite and carbonaceous matter. . . . . . 5 

3. Yellow-drab fuller's earth. The lower 

part of the ·bed is mottled and banded 

with grains and layers of dark-color~d 

oxides of iron and manganese. . . . . . . . . 1 

' 2. Greenish-yellow sand· containing some 

poorly preserved fossils. This bed is 

shown in borings in the floor of the mine 

and in wells near the mill. . . . . . . . . . . . . 50 

1. Light-yellow fltller 's earth, penetrated in 

wells near the -mill. . . . . . . . . . . . . . . . . . . . ?_ 

108 
') 

74 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

Unconformity (?). 

Eocene: Barnwell formation: 

5. Red sand................................... 10 

4. Plastic "gumbo" clay........................ 2 

3. Red sand ............................. :..... 10 

2. Concealed interval from creek to railroad level 15 

1. Marl exposures in creek bed (station 7699).. . . ? 

98 

The irregularity of the upper surface of the 

fuller's-earth bed indicates an unconformity 

between beds 5 and 6, and an unconformity at 

the same horizoQ. is seen between the red sand 

and the fuller's earth in the railroad cut at 

Pikes Peak station. In the absence of paleontologic evidence it can not be certainly stated 

whether this unconformity is within the Barnwell or whether it separates the Barnwell for- The unconformity between beds 5 and 6 

mation from the Vicksburg formation'. may be the same as that seen at Pikes Peak. 

On the property of J. D. Crump, which Turkey Oreek.-Beside the tracks of the 

adjoins that of the General Reduction Co. on Macon, Dublin & Savannah Railroad just 

the northwest, and on the Lowe' Wall property, south of Turkey Creek, 1! miles northwest of 

1 mile farther south, 12 feet of limestone con- Danville, hackly. yellow fuller's earth, sometaining Bryozoa (Rich Hill facies of Jackson what calcwreous and containing several thin 

fauna), Periarchus pileus-sinensis, and Pecten ledge~ of hard argillaceous limestone near th~ 

perplanus occurs at an altitude a little more , top, rises 10 or 15 feet above the swamp level. 

than 100 feet lower than the top of the fuller's At the top (altitude about 380 feet) is a 

earth in the section just given (which is 585 stratum of sandy calcareous clay loaded with 

feet above sea level). The limestone is under- shells of Ostrea georgiana associated with imlain by tenacious yellow sand. pres~ions of other mollusks, including a large 

Gallemore.-A fossiliferous marl, consisting of Myt~zu.s?. 

fine quartz sand in a matrix of clay and calcium ~ectwns near Dry Branch have been decarbonate, is exposed in the bed of Turkey scribed on pages 42-44 and need not be repeated 

Creek (altitude, 380 feet above sea level) at here. 

BIBB COUNTY. Gallemore, or Willis, 4 miles northeast of Danville. That this marl is a shoal-water deposit 

of Jackson age is shown by the species in the 

following list: 

Station 7699. Boulders below mill at Gallemore, Twiggs 

County, Ga. C. Wythe Cooke, collector, 1916. 

Plejona petrosa (Conrad). 

Mesalia vetusta (Conrad). 

Nucula sp. 

Leda coelata (Conrad)? 

Glycymeris staminea (Conrad)? 

Corht.ila oniscus Conrad. 

Spisula parilis Conrad? 

Panope sp. 

Meretrix sp. 

Phacoides (Miltha) claibornensis (Conrad). 

Phacoides (Miltha) pandatus (Conrad)? 

Phacoides (Here) alveatus (Conrad). 

Venericardia planicosta (Lamarck). 

All these species are represented by casts and 

molds. The following additional species, identified by T. W. Vaughan, were cited from this 

locality by Veatch and Stephenson:1 Oalyptraea aperta (Solander), Turritella carinata Lea, 

and Diplodonta ungulina (Conrad) ~ 

An area underlain by the Barnwell formation 

extends into the southern part of Bibb County 

near•Dry Branch and includes the localities at 

Browns Mountain and Bond's store which 

have already been described (pp. 4 7 --48). 

About 1! miles south of Bond's store, on the 

John Tharpe estate near the boundary between 

Twiggs and Bibb counties, the fuller's-earth 

beds become very prominent but the bryozoanbearing limestone and sandstone are absent. 

The section is well exposed in gullies above and 

below the level of the Macon-Marion road. 

Section on the John Tharpe estate, :Macon-Marion road 

10 miles southeast of Macon. 

Eocene: 

Barnwell formation: Feet. 

4. Red sand, probably extending to top 

of hill, 75 feet in all. Thickness seen 55 

Twiggs clay member: 

3. Gray hackly fuller's earth, more or 

less sandy throughout but especially 

so at top and bottom. . Crassatellites 

and fossil plants (station 7694) found 

Section along public road east from Gallemore. 20 feet below top.................. 80 

Oligocene (?):Vicksburg formation (?): Feet. 2. Yellow sand to level of road........ 20 

7. Red argillaceous sand . . . . . . . . . . . . . . . . . . . . . . . 60 Unconformity. 

6. Basal conglomerate of red sand containing Lower Cretaceous: 

limestone and quartzite pebbles........... 1 1. White plastic kaolin llJld kaolinic sand ? 

1 Op. cit., p. 256. 155 
DEPOSITS OF CLAIBORNE AND JACKSON AGE IN GEORGIA. 75 

Prof. E. W. Berry has kindly furnished the Section on Weatherly place, on east side of Shellstone Creek, 

d b Jt miles· east of Ainslie. following annotated list of plants collecte y 

the writers at this locality: 

Station 7694. Tharpe estate, 10 miles southeast of Macon. 

Acrostichum georgianum Berry (common; new to 

locality). 

Dodon.aea viscosoides Berry (common). 

Ficus claibornensis Berry (common). 

Pteris inquirenda Berry (n~w to locality; also at 

Newton, Miss.). 

Pisonia claibornensis Berry. 

Rhizophora eocenica Berry. 

Myrica nigricans Lesquereux (new to locality; also 

Green River formation of Wyoming. Referred by 

me to Cu.panites). 

Potamogeton sp. (new). 

Carpolithus najasoides Berry, n. sp. (seed). 

The following additional species were collected by Prof. Berry at the same locality: 1 

Arundo pseudogoepperti Berry. 

Conocarpus eocenica Berry? 

Malapoen.na sp. 

Mimosites georgiana Berry. 

Sphaerites claibornensis Berry. 

South and west of :Macon there ~re several 

isolated exposures of red sand with. thin beds 

of plastic clay unconformably overlying the 

liO'ht-colored sands and clays of the Upper and 

L~wcr Cretaceous and resembling the Barnwell 

deposits of northern Hou~ton County. 

BLEOKLEY COUNTY. 

As the outcrops of the Barnwell beds in 

Bibb County are typical of near-shore deposition those of the northern part of Bleckley 1 • 

County are typical of the deeper-water depos1ts 

now found near the southern limit of exposure 

of deposits of Jackson age. The deposits of 

Jackson age in this county are almost entirely 

calcareous, consisting of blue clay of the fuller'searth type, sanely marl, and bryozoan-bearing 

limestone, overlain by red sand which belongs 

largely to the Vicksburg for111-ation. . 

Residual Oligocene or Eocene: 

Vicksburg or Barnwell formation: 

6. Red argillaceous sand to top of escarpment. No sharp line of contact between 

Feet. 

this ~nd the underlying heel......... . . . 40 

Eocene: 

Barnwell formation '(Twiggs clay member): 

5. Cream-colored fuller's earth (weathered), 

with some sand. . . . . . . . . . . . . . . . . . . . . . . 20 

Ocala limestone (Tivola tongue): 

4. Hard pinkish, partly crystalline limestone. 

3. Medium hard white, highly fossiliferous 

limestone ........................... . 

1 

5 

2. Soft white porous, friable, highly fossiliferous limestone......... . . . . . . . . . . . . . . 15 

1. Creek bottom land. . . . . . . . . . . . . . . . . . . . . . 3 

84 

The following fossils from the Weatherly 

place were identified by C. W. Cooke: 

·Upper 1 foot of bed 3: 

Periarchus sp. 

Semele? sp. 

Lower 1 foot of bed 3: 

Lunulites sp. 

Flabellum wailesii Conrad? 

Endopachys maclurii (Lea)? 

Dentalium sp. 

Leda multilineata Conrad. 

Panope sp. 

Crassatellites sp. 

Bed 2: 

Bryozoa (Rich Hill facies of Jackson fauna). 

Periarchus pileus-sinensis (Ravenel)? 

Pecten perplanus Morton. 

Deese property.-Limestone and calcareous 

fuller' s~earth beds of Jackson age are well 

exposed on the.property of J. T. Deese on the 

southeast side of Shellstone Creek, 10 miles 

north of Cochran. The beds show local variations, but the following section; measured in a 

gully near the Deese residence, may be taken 

as typical. 

Section on Deese property, near Shellstone Creek. 

Ainstie.-An excellent exposureoof the Ti- Oligocene or Eocene: 

vola tongue of the Ocala limestone occurs on Vicksburg or Barnwell formation: 

tho east side of Shells tone Creek 1 i miles east 9· Red sand with chert ledges, to the flat 

Feet. 

summit of the hilL................... 50 of Ainslie. 'fhe following section is adapted Eocene: 

from that given by Brantly: 2 Barnwell formation (Twiggs clay member): 

1 Derry, E. W., The Upper Cretaceous and Eocene floras of South 

Cl\folina o.ud Georg in: U. S. Ocol. Survey Prof. Paper 84, p. 131, 1914. 

2 Br!lJltly, J. E., Georgia Oeol. Survey Bull. 21, p. 21, 1916. 

8. Blue calcareous fuller's earth, 'thin bedded, 

fossiliferous, more sandy than the underlying beds........................... 3 

0 
0 

SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

Eocene-Continued. 

Barnwell formation-ContiJRued. Feet. 

7. Thin bed of hard impure fossiliferous lime~ 

stone, probably. . . . . . . . . . . . . . . . . . . . . . 2 

6. Blue calcareous fuller's earth weathered to 

light yellowish gray at the surface. . . . . . 20 

5. Blue calcareous fuller's earth, containing 

harder and more calcareous layers.. . . . . 10 

4. Blue calcareous fuller's earth, almost free 

from sand and grit ... ·.................. 20 

3. Concealed intervaL . . . . . . . . . . . . . . . . . . . . 10 

2. Interbedded hard massive blue argilla~ 

ceous limestone and blue calcareous 

fuller's earth. (These are varying 

phases of the same formation, the hard~ 

ness depending on the percentage of 

calcium carbonate).................... 5 

1. Rotten fossiliferous limestone. . . . . . . . . . . . 5 

125 

The base of this section (altitude, about 300 

feet above sea level) is about 10 feet higher 

than the top of the Tivola tongue of the· Ocala 

limestone exposed in the escarpment of Shellstone Creek 1 ~ miles northwest of the Deese 

residence and is stratigraphically above it. 

HOUSTON COUNTY. 

North of Perry red sand extends above the 

Cretaceous-Eocene unconforn1ity to a maximum thickness of 50 feet. This bed probably 

corresponds in stratigraphic position with the 

yellow unconsolidated sands underlying the 

Tivola tongue of the Ocala limestone but may 

belong to the Midway formation. 

Sections at Ross Hill and Mossy Hill, near 

Perry, are discussed on pages ~4-46. 

In the quarry of the Planters Limestone Co., 

near the crossing of the Georgia Southern & 

Florida Railway and the Perry-Fitzgerald 

branch of the Dixie Highway, 2 miles south of 

Tivola station, the following section is exposed: 

Section in Planters Limestone Co.'s quarry, 2 miles south of 

Tivola. 

Eocene: 

Barnwell formation (Twiggs clay member): Feet. 

2. Calcareous cream-colored clay resembling 

fuller's earth, grading downward into 

argillaceous marl. This material starts 

at the top of the hill southeast of the 

quarry and is exposed in bare washes on 

the slope. There are conspicuous .harder 

and more calcareous ledges 20 and 22 

feet above the base of the member. The 

marl at the base contains numerous Bry~ 

ozoa, with Ostrea trigonalis and Pecten 

perplanus, but the upper fuller's-earth 

beds are not fossiliferous... . . . . . . . . . . . . . 33 

Ocala limestone (Tivola tongue): 

1. Soft to medium-hard light cream~colored 

to white porous bryozoan limestone, exposed from the lowest point in the quar~ 

ry to the top of the working face....... 39 

72 

The deposits of Jackson age present considerable diversity in Houston County. The 

Ti·v-ola tongue of the Ocala limestone enters the 

county from the south, with a thickness estimated by Brantly 1 at 45 feet. Its outcrop 

forms a narrow belt across the south-central 

part of the county to Grovania, and the principal exposures are in the steep escarpments 

along the south side of Indian Creek and its 

tributaries. From Grovania the limestone 

outcrop swings northward along the Georgia 

Southern & Florida Railway to Bonaire and In a gully along the raih-oad siding near the 

occupies an area more than 10 miles wide quarry a~d probably not more than. 5 feet 

between the railway and Ocmulgee River. below the bottom of ~he pit, .there is an expoThe Tivola tongue appears to be absent sure of 7 feet of medium-grained :yellow sand. 

north of Perry, but it has probably been re- The top of t~e Creta~eous can no~ he far below. 

moved from that area by erosion, for outliers f The follow~ng fossils were obtained from bed 

of the bed occur farther north at Rich Hill, · 1 of the sectiOn: . 

Crawford County. . Station 7689. Quarry 2 miles south of Tivola. Cooke and 

The Tivola tongue of the Ocala limestone is Shearer, collectors. 

overlain by the Twiggs clay member of the Orthophragn:llna, stellately marked species. 

Barnwell formation, which in this county Lepidocyclina sp. Bryozoa (Rich Hill fauna). consists principally of calcareous cream-col- Periarchus pileus~sinensis (Ravenel). 

ored clay resembling fuller's earth, forms the Cypraea fenestralis Conrad? 

upper slopes of the Indian Creek escarpment Mesalia? sp. 

and of other hills, and attains a thickness of Ostrea sp. 

about 100 feet. Pecten perplanus Morton. 

Panope sp. 

1 Brantly, J. E., op. cit., p. 82. Protocardia nicolleti (Conrad)? 
DEPOSITS OF OLAI~ORNE AND J ACKSO~ ,AG~ ~N GEO~G~. 77'· 

CRAWF<?.RD COUNTY. 

The interesting oceuri"ence.·o(strata of Jackson age at Rich Ifill, 6 miles east of Roberta, 

hasbeen well described by Veatch and ·Stephenson.1 The variability of the strata, indicating deposition near the shore, is illustrated 

by the following additional sections described 

by Shearer: 

Section in a gully on the north side'oj Rich Hill: . 

Eocene'; 

Barnwell formation: Feet. 

4. Dark-red argillaceous saud, with 

thin beds of plastic clay near the 

/ ' 

base ...... .- ... .- ... ~ .... ~......... 30 

Twiggs clay member: 

3. Fuller's-earth horizon. At the base 

the clay is greenish, coarse grained, 

and fossiliferot1s; at the top, mas-

. sive, rather plastic, and .stain~.d 

by ir<;>fl deposited from percol~ting water ...... ~ ....... ~ . . . . . . . . . 25 

2. Unconsolidated yellow sand, grad-

. ing upward into fossiliferous yellow sandy clay, which here repre~ 

sents the Tivola tongue Rf the · 

Unconformity. 

Ocala limestone ... : ...... ; . . . . . . 10 

Lower Cretaceous: 

l. Kaolinic sand with a lens of massive I 

kaolin at the· top ... ,; .. ~ ...... ~.: 100+ 

165 

Section in a gitlly'on the -south side of Rich Hill . . 

Eocene: 

Baniwell fo'rmation (upper part): Feet. 

8. Dark-red argillaceous sand, with 

thin beds of plast~~. ~lay near ~he 

base ................ ~ ...... : .. .- : 40 

Twiggs clay member: 

7. Fuller's-earth horizon. The clay is 

light greenish yellow in color, very 

slightly calcareous at the top but 

becoming more so toward the 

base ........................ :... 10 

Ocala limestone (Tivola tongue): 

G. Hard massive argillaceous limestone ................. ·.......... 3 

5. Soft massive argillaceous limestone, 

with few if any fossils............ 7 

4. Bryozoan limestone of varying hard-

·ness. This.is the bed from which 

the fossils listed below were collected........................... 10 

3. Sandy marl (gradational phase).... ! 

Barnwell formation (basal part): . 

2. Unconsolidated light-yellow sand.. 25 

Unconformity. 

Lower Cretaceous: 

1. kaolinic sand with lenses of massive 

kaoliu ......... ~ ... : ............ 100+ 

1 Op. cit., pp. 299-300. 

28288°-19-6 

195+ 

The fossils from Rich-.J;liH, l~sted by ·.T. · w~·· 

Vaughan in the Cqastal Plain report, 2 are aS. 

follows: 

Periarchus pileus-sinensis (Ravenel). 

:Plejona sp. 

Calyptraea aperta (Solander). 

Ostrea ·georgiana Conrad·. 

_P~ctep perplanus M-<>.rton. · · ' · ,,_. ::.·· 

Pecten (propably P. nuperus Conrad), you~g ·and. 

po<;>r specimen. 

Venericardia sp. . 

Lucina sp., found also 5! miles south· of Perry. ·: 

Panope sp. 

Th~ calcare<;ms bed~ of the prec~ding ~~c-· 

tio:r;ts ar~ of undoubted Jackson age, and t~e 

Bryozoa of. the Rich Hill facies of the J a~kson 

fauna, as identified by R. S. Bassler, foriQ. 

valuable horizon markers. 

The unconfo;rmity on the south side of the 

hill is 25 feet lower than that on the north 

side, showing an erosion d~pressi"o.p. . ~n . t.~~ 

Cretac~ous surface, and in this depre~sion the. 

sand, and J.imestone be~s ~·epre$entmg 'tlie 

Ocala are much thicker than over the old 

hilltops. . . T·he base 9~ the d.epos.its ~f J ~~~SP~. 

age here is consi~erably higher ~f~n 'at any 

point in Ho':lston or Twiggs pou.n,ties, but. t:P.e. 

exact altitude is not known. The altitude of 

the top of the hillis probably' ab<;>ut 700 'feet~· 

OCALA.' LIM~STO~E. 

AREA NORTH OF ·DOOLY COUNTY. 

The local details of the Ocala limestone in 

the area north of Dooly County have been 

given in the preceding discussion of ~he Ba~nwell formation and will not be repeated here. 

The type locality of the Tivola tongue . of the 

Ocala limestone is described on page 76. 

DOOLY COUNTY. 

The Twiggs clay member of the Barnwe)l 

formation extends southward from Houston 

County into Pooly County 'J?ut becomes increasingly calcareous· and merges into the Om1J~ 

limestone. '!_'he .Tivola tongue qf the O<?~la · 

limestone is well develope~· in Dooly Cop.nty 

and has been seen at a number of natural. 

exposures. 

On the J. M. Carter pr9perty, 1! miles southeast of Lilly, 20 feet or more of soft white limestone composed largely of Bryozoa bu~ containing also Pecten perplanus and P eriarchus 

2 Georgia Geo.l. Survey Bull. 26, p. 300, 1911. 
78 SHOR.TE;R CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

pileus-sinensis is exposed. Brantiy. 1 reports The last two species named were fQ~d also 

20 feet of limestone overlain by 17 feet of at' the railroad bridge below ·spring Creek 

calcareous fuller's earth on the L. Frieden prop- (station 7108). · · · 

erty, 9 miles east of Montezuma. At a small quarry on the Averitt property, 

EXPOSURES ON AND NEAR FLINT RIVER. 300 or 400 yards SOUthwest of the corner of 

Strata of Jackson age first appear in the lots 7 and 26! half a mile east of Hugunen 

banks of Flint River about 3-! miles above the Ferry and 1 I_Uile south of Daphne station, Crisp 

crossing of the Seaboard Air Line Railway west .~ounty (statwn_7~37), the rock is a soft white 

of Cordele. From this point exposures occur )Imestone containmg Orthophragmina jlintensis 

at short intervals to Fort Scott, about ·11 miles · Cus~an, numerous Bryozoa, and an uncleabove the .confluence of Flint and Chattahoo- . termin~d pecten, probably Amusium ocalanwn 

chee rivers. As most of the exposures show (Dal~): ~ analysis of the limestone from this 

little diversity, detailed discussion here will be loca~Ity given by Brantly3 shows 85 per cent 

restricted to those which have furnished the calCium carbonate. Better exposure~ of this 

best collections of fossils or which are other- rock occur in a sink about 300 yards east of 

wise of interest. the quarry, where 23 feet of soft argillaceoue 

The lithologic variation in the Ocala lime- white ~me~tone. co~taining. small specks of 

stone, as displayed along Flint River, is slight. glauconite IS ove~lain by 18 feet of reddish 

In the upper reaches of the river the rock sandy loam. The course of an underground 

which presumably constitutes the lower portio~ stream that flows through this sink can be 

of the formation, is prevailingly finer grained traced ~orthwest~ard b~ means of _long,_ narand less harsh in texture than that farther row slot-shaped sinks whiCh expose It at Intersouth, where tests of Foraminifera and Bryozoa vals to Gum ~reek. . . 

compose a large proportion of the limestone. The following sectiOn, which was measured 

Above Albany.-The following fossils were by J. E. Bran~ly a~d C. ~ythe Cooke on the 

obtained from the Ocala limestone on Flint east bank of Flint Riv~r 1 mile above the mouth 

River 3 miles above the Seaboard Air Line of Ced~r Creek, Crisp County, is quoted with a 

Railw~y bridge: few ~nnor changes from Brantly's report on 

Station 7106. Flint River at mouth of Sprl.ng Creek, the limestones and marls of Georgia.' 

Sumter County. Brantly and Cooke, collectors, 1914. 

Orbitoid Foraminifera. 

Flabellum wailesi· (Conrad)? 

Schizaster :floridanus Clark? 

Turritella sp. 

Nucula sp. 

Pecten perplanus Morton. 

Crustacean. 

The Ocala limestone exposed at this locality 

consists of about 14 feet of white or creamcolored limestone in thin beds,· alternating in 

degree of hardness a:nd containing a little glauconite. Analysis of the rock shows· 85.8 per 

cent calcium carbonate. 2 

A quarter of a mile below this point the following fossils were Qbtained: 

Station 7107. West bank of Flint River a quarter of a 

mile below the mouth of Spring Creek. Brantly and 

Cooke, collectors. 

Orbitoid Foraminifera. 

Bryozoa. 

Periarchus, probably·P. pileus-sinensis (Ravenel). 

Mitra? sp. 

Pecten perplanus Morton. 

Amusium ocalanum (Dall). 

1 Brantly, J. E., op. cit., p. 112. 

2 Idem, p. 120. 

Section of Limestone Bluff on Armstrong place. 

Pleistocene: 

.11. Sands and gravel. ....................... . 

Ft. in. 

7 0 

Ocala limestone: 

10. Mostly concealed, but with several small 

exposures of soft white, finely granular 

limestone and hard, partly crystalline 

light-gray limestone. Bryozoa, Pecten, 

etc................................... 8 

9. Hard, very light gray crystalline limestone ................................ . 

8. Alternating 6 to 10 inch layers of soft and 

slightly harder white, finely granular 

limestone: . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

7. Hard, very light gray crystalline limestone ........................ : ....... . 

6. Alternating 6 to 10 inch layers of soft and 

slightly harder white, finely granular 

limestone... . . . . . . . . . . . . . . . . . . . . . . . . . . 7 

5. Medium-hard white, partly crystalline 

limestone. . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 

4. Soft white limestone.................... 4 

3. Hard white limestone containing Bryozoa; iorms a projecting ledge........... 4 

2. Soft light-gray limestone, with specks of 

glauconite and a few nodules of chert.. . 8 

8 Idem, p. 158. 

t Idem, p. 159. 

0 

3 

6 

3 

6 

0 

0 

0 

0 
DEPOSITS OF CLAIBOR.NE AND JACKSON AGE IN GEORGIA. 79 

Ocala limestone-Continued. 

1. Hard white, partly crystalline limestone, 

irregularly weathered, to water's edge 

at 2-foot stage, Contains (station 7110) 

Lumtlaria distans and other Bryozoa, 

Flabellttm, Nttcula, Glycymeris, Pecten, 

AmttSittm ocalamtm, and Crassatellites. . 2 6 

On the east bank of Flint River at the bend 

to the west 6 miles below Burke Ferry and 

about 6 miles above the bridge of the Georgia 

Southwestern & Gulf Railway, near Warwick, 

Worth County (station 7115), the material 

exposed consists of white compact limestone 

rising 5 feet above water level and overlain by 

flint boulders, sand, and gravel. Orthophragmina fiintensis Cushman ·and Operculina sp. 

were collected here. 

The section at a bluff on the west bank of 

Flint River about 1! miles above the bridge 

of the Georgia Southwestern & Gulf Railway is 

as follows: 

Section in bltt.ff on west bank of Flint River. 

Feet. 

3. Covered slope to top of hill.. . .. . . . . . . . . . . . . . . 22 

Ocala limestone: 

2. Hard ledges of compact white semicrystalline 

limestone (station 7117).... . . . . . . . . . . . . . . . . 3 

1. Compact white limestone, mostly soft but 

with harder places. Contains (station 7116) 

Orthophragmina Jlintensis and Laganum? 

crustuloides (Morton)? To water level at 

4-faot stage............................... 20 

From bed 2 (station 7117) were collected the 

following: · 

Foraminifera: 

Orthophragmina :Bintensis Cushman. 

Bryozoa: 

Several species. 

Echinodermata: 

Laganum? crustuloides (Morton)? 

Mollusca: 

Ostrea sp. 

Pecten perplanus Morton. 

Pecten suwaneensis Dall. 

On the east bank of Flint River in Worth 

County near the Dougherty County line, about 

16 miles above Albany (station 7119), the 

rock consists of 5 feet of limestone, the upper 

part white, lower part gray, overlain by flint 

fragments. It contains Orthophr:agmina fiintensis Cushman, Operculina sp., and Pecten 

suwaneensis Dall. On the east bank of Flint 

River in 'Dougherty County, about 8 miles 

above Albany, at the mouth of a small creek 

(station 7235), the following fossils were obtained from soft white limestone, 8 feet in 

exposed thickness, containing concretionary 

masses of hard limestone: 

Bryozoa. 

Laganum? crustuloides (Morton).· 

Schizaster fl.oridanus Clark? 

Macropneustes mortoni (Conrad)? 

Ostrea sp. 

Pecten perplanus Morton. 

Pecten suwaneensis Dall. 

(/Vicinity of Albany.-The following section 

was observed in the bank of Kinchafoonee 

Creek at the power plant 2 miles north of 

Albany: 

Section on Kinchafoonee Creek 2 miles north of Albany. 

Feet. 

4. River sands....... . . . . . . . . . . . . . . . . . . . . . . . . . . 15 

Ocala limestone: 

3. Hard pink or yellow limestone with Cidaris 

georgiana and Amu..num ocalanum.......... 2! 

2. Hard pinkish limestone with Bryozoa, echinoids, and Amusium ocalanum. . . . . . . . . . . . . 2! 

1. White, cream-colored, or yellow granular limestone with Amusium ocalanum and casts of 

corals. To water level in Kinchafoonee 

Creek.................................... 5 

Above bed 3 there is reported to be 5 feet 

of limestone which was inaccessible at the 

time this section was measured. Other sections at this locality that do not differ materially from this have been ·recorded by Veatch 

and Stephenson 1 and by Brantly.2 

The fossils in the following list were collected 

from loose blocks on the dump heap below the 

dam at the power plant: 

Station 7121. Excavation below dam ·at power plant on 

Kinchafoonee Creek 2 miles north of Albany, Ga. 

Cooke and Brantly, collectors, 1914. 

Foraminifera: 

Operculina sp. 

Echinodermata: 

Cidaris georgiana Twitchell. 

Cassidulus (Rhynchopygus) depressus 

Twitchell? 

Cassidulus (Pygorhynchus) conradi (Conrad). . Eupatagus carolinensis Clark? 

Linthia wilmingtonensis Clark? 

Macropneustes mortoni (Conrad). 

Mollusca: 

Eucymba ocalana Dall. 

Cypraea fenestralis Conrad. 

Ostrea sp. 

Gryphaeostrea sp. 

Pecten perplanus Morton, varieties. 

Amusium ocalanum Dall. 

Mya.? sp. 

1 Veatch, Otto, and Stephensou, L. W., op. cit., p. 316. 

1 Brantly, J. E., op. cit., p. 135. 
80 SHOR.TER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

Between ·Albany and Red Bluff.-The following fossils were found in white, gray, or cream:--

colored limestone extending about 2 feet above 

water level. . 

Station 7125. West bank of Flint River in Baker County 

about 3 miles below Dewberry Ferry (Bacont~m Landing) and about 13 miles above Newton. Brall.tly and 

Cooke, collectors, 1914. 

Flabellum sp. 

Cypraea fenestralis Conrad. 

Cerithium sp. 

Turritella sp. 

Calyptraea.sp. 

Glycymeris sp. 

Pecten perplanus Morton. 

.. Pecten indecisus Dall. 

Amusium ocalanum (Dall)? 

Spondylus sp ... 

Plicatula, Ocala sp. 

Venericardia sp. 

· The .following species were collected from 

lumps of hard limestone excavated from the 

channel: 

Station· 7126. East bank of Flint Riv~r at Dry Breacl 

·Shoals, Mitchell County, 8! or 9 miles below Newton. 

Forarq.:inifera: 

Orthophragmina mariannensis var. papillata 

Cushman. . ·· · 

Orthophragmina georgiana Cushman. 

Anthozoa: · 

. Trochoseris n. sp. 

Echinodermata: 

Cidaris georgiana Twitchell. 

Laganum? crustuloides (Morton)? 

Oligopygus haldermani (Conrad). 

Mollusca: 

Mitra sp. 

Chama sp. 

Limopsis sp. 

Barbatia sp. 

Ostrea trigonalis Conrad. 

Amusium ocalanum (Dall). 

Pecten perpl-anus Morton. 

Spondylus sp. 

Plicatula, Ocala sp. 

Mya? sp. 

V enericardia vicks burgiana Dall. 

Venericardia sp. 

Crassatellites sp. 

Station 7127. Loos~ blocks excavated from the channel of 

Flint River, a'quarter of a mile below Norman's Ferry, 

Mitchell County, midway between Newton and Bainbridge. Cooke and ~rantly, collectors, 1914. 

Lepidocyclina sp. and other Foraminifera. 

Lunularia sp. and other Bryozoa. 

- Cidaris georgia~a Twitchell. 

Oligopygus haldermani (Conrad). 

Laganum sp. 

· Cypraea sp. 

I 

Station 7127-Continued. 

Xenoph01:a sp. 

Glycymeris sp. 

Barbatia sp. 

Amusium ocalanum (Dall) var. 

Spondylus sp. 

Lima halensis Dall. 

Plicatula, Ocala sp. 

Chama sp. 

Crassatellites sp. 

Venericardia sp. 

Mya? sp~ 

. On the east bank of Flint River in Decatur 

County, l·mile below Windell's Landing and 

aqout 15 miles above Bainbridge (station 7129), 

Orthophragmina mariannensis var. papillata 

Cushman and an undetermined species of 

Pecten were found in 5 feet of irregularly. 

· weathered pinkish limestone. 

Vicinity of Bainbridge.-The Ocala limestone is the oldest formation in the vicinity of 

Bainbridge, and all its exposures appear to . 

represent a single horizon. It is a soft, coarsely 

granular limestone varying in color from white 

to yellow and composed largelY. of tests of 

Fora~inifera and Bryozoa, whi<;h on exposed 

s11rfaces have become firmly cemented or 

''case-hardened" into a brittle, semicrystalline 

limestone, but which when freshly exposed are 

only slightly coherent. The rock appears to 

lie v:ery nearly horizontal, but the upper sur-

.face is exceedingly irregular and jagged, with 

. pinnacles extending in places to 20 feet 

above water level. The irregularity is due in 

part to erosion prior to the deposition 

of the overlying materials and in part to 

subsequent solution. The Ocala is overlain 

unconformably by a complex series of red and 

variegated sands and carbonaceous clays containing chert fragments with impressions and 

siliceous pseudomorphs of mollusks and corals 

of lower Oligocene age. The Ocala itself appears to have been subjected to the silicifying 

agencies to a lesser extent, for chert fragment::; 

carrying Ocala fossils are only ·occasionally 

found. The accidental inclusion of some of 

these in the collections of the coralliferous 

chert has unfortunately been interpreted as a 

mingling of .the' Ocala and Chattahoochee 

faunas. 1 

The following species have been identified 

from localities near Bainbridge: 

1 Dall, W. H., A contribution-to the invertebrate fauna of the Oligocene 

beds of FUn~ ~iver, Ga.: U.S. N~t. Mus. Proc., vol. 51, p. 488, 19~6. 
DEPOSITS OF CLAIBORNE AND .JACKSON AGE IN GEORGIA. 81 

Station 7099. East bank of Flint River half a mile above Station 7097-Continued. 

Reel Bluff. C. Wythe Cooke, collector. Bryozoa: 

Foraminifera: About 34 species, most of them new. 

Orthophragmina georgiana Cushman. Echinodermata: 

Bryozoa: Cidaris georgiana Twitchell. 

Many species. Cassidulus (Pygorhynchus) conradi (Conrad). 

Echinodermata: Oligopygus haldermani (Conrad). 

Oligopygus haldermani (Conrad). Agassizia conradi (Bouve). 

Agassizia con.radi (Bouve)? Eupatagus carolinensis Clark? 

Stations 3387, 6159, 7098. Red Blu(f, Flint River, 7 miles Mollusca: 

above Bainbridge. Vaughan, Stephenson, and Cooke, Ostrea, 2 sp. 

collectors. Pecten perplanus Morton. 

Foraminifera: Amusium ocalanum (Dall). 

Orthophragmina americana Cushman. Plicatula, Ocala sp. 

Orthophragmina mariannensis Cushman. Cardium sp. 

Orthophragmina georgiana Cushman. Stations 3293, 6171. Bainbridge. A. H. Brooks and L. W. 

Orthophragmina vaughani Cushman. Stephenson, collectors. 

Bryozoa: Lepidocyclina sp. and other Foraminifera. 

Mn.ny species. Bryozoa, many species. 

Echinodermata: Cidaris georgiana Twitchell. 

Oligopygus haldermani (Conrad). Cassidulus (Pygorhynchus) georgiensis Twitchell. 

Laganum? crustuloides (Morton)? Oligopygus haldermani (Conrad). 

Cassidulus (Pygorhynchus) georgiensis Twit- Ostrea trigonalis Conrad. 

chell. Pecten perplanus Morton. 

Agassizia conradi (Bouve). Amusium ocalanum (Dall). 

Mollusca: 

Pecten perplanus Morton. 

Pecten indecisus Dall. 

Pecten suwaneensis Dall. 

Amusium ocalanum (Dall). 

Station 70!)7. Bluff on east side of Flint River near old 

factory three-quarters of a mile north of the Atlantic 

Coast :Line Railway station at Bainbridge. Vaughan, 

Cooke, and Mansfield, collectors. 

Foraminifera: 

Orthophragmina georgiana Cushman. 

Lepidocyclina sp. and many others. 

EXPOSURES WEST OF FLINT RIVER. 

For local details of the Ocala limestone west 

of Flint River, the reader is referred to the 

county descriptions in Brantly's report on the 

limestones and marls of the Coastal Plain of 

Georgia. 1 

1 Brantly, J. E., Georgia Gcol. Survey Bull. 21, 1916. 

TI-lE STRUCTURE AND STRATIGRAPHY OF GRAVINA AND REVILLAGIGEDO 

ISLANDS, ALASKA. 

By THEODORE CHAPIN. 

INTRODUCTION. LOCATION. 

SCOPE OF PAPER. The area under discussion is included within 

· This paper is intended to supplement a the Ketchikan district, which lies in the southreport by Philip S. Smith1 on the same region. ern part of southeastern Alaska, the panhandle · 

Tho finding on Gravina Island of 

Triassic fossils, which previously 

had been reported from but one 

other locality in southeastern 

Alaska, 1nade his paper of particnlar interest. Since the publication of Smith's report the 

writer has had the opportunity to 

make further studies and to.gather 

additional data on the structure 

and stratigraphy of the rocks of 

Gra 'rina Island and adjacent regions. The discovery of fossils of 

Jurassic or Cretaceous age has 

made possible some changes in the 

geologic mapping and furnished 

the basis for the interpretations 

which are here presented, not as 

final conclusions butasareasonable 

working hypothesis for future field 

work. The structure and stratigraphy of the rocks of Gravina 

Island are more clearly understood 

by a consideration of their relation 

to a larger area including a part 

of Revillagigedo Island (fig. 10). 

'rhis paper is a preliminary re-

~ 

r---------~~~----------~~~~~~~~~--un 1> 

0......._.._._......._._50...........,......_.,_10._0 _____ __;:,o200 MILES 

138 

port On an area in the SOUthern FIGURE 10.-Map of southeastern Alaska showing position of Gravina and Revillagigedo 

part of the Ketchikan district. islands. 

A more complete report on the whole district, strip of Alaska extending along the seaboard 

incluging a description of. the mineral resources, from Mount Fairweather to Dixon Entrance·. 

is now in preparation. The accompanying Southeastern Alaska is composed of a mainland 

geologic sketch map (fig. 11) is drawn from the area and a fringe of islands known as Alexanfield notes of P. S. Smith and the writer. der Archipelago. The Ketchikan district lies 

1 Notos on tho geology or Gravina Island, Alaska: U.S. Geol. Survey 

Prot. Paper 95, pp. 97-105, 1915. 

wholly within the Pacific Mountain system, ! a 

geographic province which, as defined · J?i 

83 
84 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

Brooks, 1 includes a broad zone of ranges forming a conca\ .:; belt parallel to the southern 

coast of Alaska. 

SURFACE FEATURES. 

PHYSIOGRAPHIC PROVINCES. 

Physiographically the Ketchikan district 

falls naturally into three main provinces. One 

comprises essentially the mainland area· and 

\) 

The dominating feature of. the mainland 

province is the Coast Range, a high mountain 

mass with elevations 0f 7,000 to 8,000 feet. 

Brooks 2 describes it as follows: 

The Coast Range extends from near the boundary of 

Washington northward through British Columbia into 

southeastern Alaska, where it lies partly in Alaska and 

partly in Canadian territory. Following the coast line 

for nearly 900 miles it passes inland behind the St. Elias 

A N N' E T T E 

IS LAN 0 

LEGEND BEDDED ROCKS, 

Rhyolite H ~ J~~i! &:a:-11-

Conglomerate,slate, ;)~g:i 

an~cke }~~0 

-~;)<(:I G'"•To"•·r·te r 

Slate,sandstone,lime· ~ 

stone,and phyllite g~ 

• 

!::!~::! 

:::~~ 

~t~ r·t:r ,~ 

Con[]]J[]Jglomerate }~~ 

o .. o 

Crystalline schist ~f~ 

Va~~~~;1:T:.~on }t (Conglomerate, lime- c stone, and shale) 

INTRUSIVE: ROCKS 

Quart:z ~ diorite 

and granite 

0 

Strike and dip 

5E3:=::E~=::;;:e:::::;;;:i:O=:=:=:=:=:=:=::=i5=:=:=:=:=:=::==310 MILES 

FIGURE iL-,G~ologic sketch map-of Gravina Island and a part of Revillagigedo Island, Alaska. 

adjacent islands.''- It inchides the Coast Range Range riear the head of Lynn CanaL Thence it can be 

and may be denominateq. the Coast Range or traced northward, decreasing in altitude and 'gradually 

:mainland province. The eastern or Prince of losing definition· until it finally merges with the interior 

plateau near Lake Kluane, in longitude 130° 30'. This 

Wales Province comprises Prince of Wales Is- range has no well-defined crest line but is rather' a comland and· the islands to· the west. Between plex of irregular mountain masses occupying a coastal 

these·· two mountaino~us areas lies an inter.:.. strip between tlie Pacific Ocean and the Central Plateau 

montane lowla~d province including Clarence region. 

'Strait, Revillagigedo Channel, and Behin Canal The Prince_. of Wales· physiogr~phic province 

.. and low-lying- areas along' their shores. . . .... ;:. is 'don:iinated by a complex .group of short, 

1 Brooks, A. ii., Preliminary report on the Ketchikan mining district, 

Alaska: U. S. Geol. Survey Prof. Paper 1, p. 14, 1902. 

2 Brooks, A. H., The geography and geology of Alaska: U. S. Geol. 

Survey Prof. Paper 45, p. ~8, 1906. 
GRAVINA AND REVILLAGIGEDO ISLANDS, ALASKA. 0

85 

rugged ranges reaching elevations of about 0 Gravina Island lies along the border line 

4,000 feet. In the northern part of the Alex- between the Coast Range and lowland provander Al.·chipelago these are not sharply dif- inces. 0 Two low ranges of hills, the California 

ferenti11ted from the Coast Range and· were Range and Dall Ridge, extend across the entire 

regarded by Brooks as 11 southeastern extension island from northwest to southeast. Dall 

of the St. Elias Range. 1 In the Ketchikan Ridge r·eaches a maximum elevation of about 

district, however, 11s h11s been pointed out, the 2,000 feet, and California Range of over 2,500 

Prince of V\7 ales mou.nt11inous region is quite feet. Between these two ranges of hills, exdistinct from the Coast Range, from which it is tending from Vallenar Bay to Bostwick Inlet, . 

separated by the lowl11nd province·. It is cor- is a low depression only a few feet above sea 

related with the V 11ncouver Range, onamed by level. Another depression extends from Blank 

D11wson 2 and consisting .of" ali irregular moun- Inlet to a point opposite Ward Cove. It lies 

tain system which in its submerged parts between California Range and a low r11nge that 

constitutes Vancouver Island and the Queen borders Tongass Narrows from Gravina Point 

Ch11rlotte Islands." northward for about 4 miles. 

The lowland province as here defmed com- A striking parallelism exists between the 

prises the sub1narine area covered by the waters ranges of hills, the i.nterv~ning valleys, and the 

of Cln.rence Strait, Revillagigedo Channel, and large bays-Vallenar, Bostwick, and Blank 

Nichols Pass~ge, and the bordering lowlands. inlets. All have a dominant northwesterly 

1'his lowland is evidently a submerged portion clirection, approximately parallel to the strucof the Pacific coast downfold,3 a series of basins ture of the bedrock, which has evidently been 

forming a more or less continuous depression the controlling factor in the topographic 

extending fron1 the ·Gulf of California to development. 

British Columbia and 1Uaska. This lowland 

province would thus be correlated with Puget 

Sound 11nd with the lowl11nds covered by the 

sound sepoarating Queen Charlotte and V 11ncouver isl11nds in British Columbia from the 

m11inland. The 11rea under discussion lies 

wi-thin and along the border of this lowland 

· provii1ce, 11n a.rea covered iargely by Mesozoic 

sediments which apparently occupy an overturned synclin11l fold. 

REVILLAGIGEDO ISLAND. 

Revillagigedo Island, with the exception of a 

fringe of lowland along Tongass Narrows, belongs to the main] and province. It is a large 

island of 1,120 square miles separated from the 

mainland by Behm Canal, a semicircular fiord 

'that borders the northern p11rt of the island. 

The interior of the island is high and rugged, 

its pe11ks reaching elevations of 4,000 feet. 

Three long fiords-Thorne Arm, Carroll Inlet, 

GRAVINA ISLAND. and George Inlet-break the southern coast 

Gravina Island lies b~tween Clarence Strait 0 

into irregular-shaped peninsulas. 

and Revillagigedo Chani1el and is separated SUMMARY OF FORMATIONS AND STRUCTURE. 

from Revillagigedo Island by Tongass Narrow's, . 11 n11rrow, sh11llow channel a quarter of a mile .. The rocks. of ?ravina Islan~ and th~t po:- ~ 

to 2 miles wide and in pl11ces less than 100 feet ti_on of. Revillagiged~ Island Inc~uded In .this 

deep. 'fhe island is roughly triangular~ It discussiOn are essentially l\{esozoiC for~atwns 

has rather straight shore lines on two coasts, that rest u_nconformably upon Carbonifero~s 

but the southe11st coast is very irregular iii and D~von~an rocks ·(fig. ~.1),- The Mesozoic 

sh~pe, being broken by two deep bays, Blank format~ons Include :t~ee distmct terranes, all 

and Bostwicic inlets, and by n1inor indenta- of whwh ar~ fossi~Iferous. Th~ lower an~ 

tions. The lo~1gest dimension of the island is upper terranes, whi~h are ~om~antly ~edi:.. 

21 Iniles, and its maximum width is 9 miles. mentary, are ~espectively Triassic a.nd either 

It has an area of about 100 square miles. Upper Jur.assiC or. Lower ~~etac~ous .. ':fhe 

,o . terrane· of Intermediate stratigraphiC .pOsitiOn, 

o 1 Brooks, ,A, H., Tho geography tmd geology of Alaska: U.S. Gcol. composed of volcanic rocks ai'ld intercalated Survey Prof. Pap,or 45, p. 29, 1906. 

s Dll\\~Soon, a.M., Roy. Soc. Canada Proc. and Trans., vol. 8, so~. 4, sediments~ contains fossils· of Upper Jurassic or 

p. ·

1

• 

1

890. · 0

• Lower Cretaceous age but may include also u Willis, Bal.loy, U.S. Gaol. Survey Gaol. Atlas, 'l'acomafolio (No. 54), 

p.1, 1899. · · . : 0 

0 0 

• : • • • Triassic rocks.. Ter'tiary lava .flows occur on· 

• 
0 

86 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

the southern part of Gravina Island but are not 

widely distributed. The most recent formations are marine glacial deposits that lie above 

the present high tide. 

The intrusive rocks of the Ketchikan region 

comprise for the most part the dioritic and 

granitic rocks of the Coast Range. They are 

not, however, oonfined to the Coast Range but 

occur in large bodies on the islands. The age 

of these intrusives is regarded as late Jurassic 

. and Cretaceous. 

The following table shows the correlation of 

the Mesozoic formations of Gravina Island with 

those of Graham and Vancouver islands as 

described by Canadian geologists.: 

Island Triassic conglomerate, limestone, and 

black slate are overlain by volcanic rocks and 

intercalated sediments of Triassic or Jurassic 

age, which, in turn, are overlain by the slate 

and graywacke of Blank Inlet, determined to 

be Jurassic or Cretaceous. Succeeding the 

Jurassic or Cretaceous sediments are volcanic 

rocks, with black slates and tuffs. Here the 

section is interrupted by a boss of granite, 

beyond which are black slates and phyllites, 

limestone, and schistose conglomerate. Beyond the conglomerate occur crystalline schists 

and massive semicrystalline_limestone-bearing 

fossils regarded as certainly Paleozoic and 

probably Carboniferous. This anomalous posiCorrelation table of :Mesozoic formations of Gravina, Graham, and Vancouver islands. 

Graham Island.a Vancouv~r Island.b 

Age. Gravina Isiand. 

Formation. Lithologic character. Formation. Lithologic character. 

Upper Creta- I Queen Char- Fossiliferous· shales N anaimo· se- Conglomerates, sandceous. lotte series. and conglomerates, ries. stones, and shales, 

with coal. with coal. 

Lower Creta- Conglomerate, sand- ceous. stone, and gray- I wacke .. Batholithic Batholithic 

Upper Juras- Granodiorites, Quartz diorite, etc. intrusives, Quartz diorite, etc. and dike in- quartz 

SlC. diorites, etc. etc. trusives. 

Andesitic flows and Sicker series 

Middle Juras- Volcanic flows and Yakoun for- Agglomerates, tuffs, (Jurassic or tuffs ; schistose, slaty, 

sic. tuffs with interca- mation. and flows. Triassic). t u ff a c e o u s, and 

lated sediments. quartzose sediments. 

Volcanic breccias. 

Lower Juras- Dark-colored, :fi n esic. 

Maude forConglomerate, lime- mation. 

Upper Triassic. stone, sandstone, 

and slate. 

a Mackenzie, J.D., Canada Geol. Survey Mem. 88, 1916. 

Across the area including Gravina Island 

and the southern part of Revillagigedo Island 

the beds present a domin~nt northwest strike 

and, except locally, dip northeast, giving the 

appearance of simple monoclinal structure 

ov:er a wide area. (See fig. 12.) These beds, 

however, are believed to represent overturned 

and truncated isoclinal folds and thus give the 

impression of a much greater thickness of sediments than really exists. The evidence for 

this conclusion lies in the following observed 

facts. On the southwest coast of Gravina 

grained, thinly 

laminated fossilif- erous argillites, Sutton forma- Crystalline limegrading upward into tion, Van- stones, metamorphic 

tuffs and agglomer- couvervol- andesites, and pyro..: 

ates. P o s s i b 1 y canics. clastic rocks. 

detrital conglomerates at base. 

b Clapp, C. H., Canada Geol. Survey Mem. 13, 1912. 

tion of the Paleozoic and Mesozoic rocks is 

probably due to an overturned position of one 

limb of the syrlcline. 

From the slate and graywacke area of Blank 

Inlet the general sequence of rocks is the same 

toward the northeast as it is toward the southwest, and it is believed that the similar rocks 

are in fact the same beds exposed on two limbs 

of an overturned fold, the trough of which is 

exposed on Blank Inlet. The volcanic rocks 

on each side of the Blank Inlet area of slate and 

graywacke are similar and may be correlated, 
GRAVINA AND REVILLAGIGEDO ISLANDS, ALASKA. 87 

as there is little reason to doubt their identity. 

Tho slates and phyllites of Revillagigedo 

Island are much more schistose than the black 

slates and sandstones of Gravina Island, with 

which they are corr~ated, but' this is evidently 

due to the contact metamorphism caused by 

the adjoining intrusive granite. The other 

sediments of Revillagigedo Island are also more 

metamorphosed than their supposed equivalents on Gravina Island. The lin1estone is 

crystalline and the conglomerate is schistose, 

but these differences in metamorphisn1 are also 

easily accottnted for, not alone by the smail 

body of granite sho,vn in the sketch but also 

by the immense batholith of the Coast Range. 

Along this eastern lin1b of the syncline is 

a greatly disturbed belt which apparently 

continues the entire length of southeastern 

Alaska along the border of the intrusives of the 

Coast Range. In this disturbed belt .the foldsw. 

TRIASSIC (in part or wholly UpperTriassic::) 

·S 0 

bedded with thin limestones, calcareous shales, 

argillites, and sandstones containing Devonian 

fossils. 

STRUCTURE AND STRATIGRAPHY. 

The structure and stratigraphic relations of 

the Devonian beds are not clear. The beds 

are closely folded and deformed, and the relations are obscured by 1novement along the contacts. From South V al.lenar Point eastward 

the beds trend dominantly northwest and dip 

northeast at varying angles. From the present 

position of the beds the base of the formation 

appears to be the conglomerate, which appar- e 

ently rests upon the Mesozoic volcanic beds of 

the west coast of the island. This anomalous 

condition indicates an overturned position of 

the beds. 

· On the west coast of V allenar Bay, about a 

mile east of South V allenar Point, is the crest 

NE •. 

TRIASSIC CARBONIFEROUS 

(in part or wholly Upper Triassic) (probably late CarbOniferous) 

5 10 Miles 

FIGURE 12.-Structuro section across Gravina and Revillagigedo islands, Alaska. 

ing is much more close, and the beds are more 

tightly compressed and, if correctly interpreted, 

are in part overturned. The structural form is 

not a simple syncline and might more correctly 

be termed a synclinoriun1, for one prominent 

anticline and a number. of n1inor folds occur, 

the details of which are brought out more fully 

in the discussion of the different formations. 

DEVONIAN ROCKS. 

VAL.LENAR FORMATION. 

DISTRIBUTION AND CHARACTER. 

The oldest rocks recognized by the writer 

are tho Devonian beds exposed on the west 

coast of Vallenar Bay, on Gravina Island. 

They consist of eonglomerate, limestone, calcareous shales, sandstone, and argillites. The 

conglomerate is composed of cobbles of schist, 

quartz, and limestone embedd~d in a schistose 

matrix. The conglomerate is in part interof a very sharply folded anticline (Pl. VIII, D), 

which has involved the calcareous shales and 

argillites. It is believed that these are the 

lowest of the Devonian beds and that the limestones and conglomerates to. the west are 

stratigraphically higher in the section and 

occupy the overturned limb of a steeply pitching anticline that is overturned toward the 

west. It may be that the schistose conglomerate containing an abundance of limestone 

cobbles is a member of the Mesozoic greenstone 

and intercalated sedimentary beds. The contact with the Mesozoic beds at the head of 

V allenar ·Bay is covered by gravels. This 

anticline along which the Devonian beds are 

brought to the surface on V allenar Bay is presumably the same fold that extends along Dall 

Ridge to Seal Cove and forms a minor fold in 

the broad synclinorium involving all the rocks 

between the west coast of Gravina Island and 

George Arm. 
88 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

AGE AND CORRELATION. 

The Devonian rocks. of V allena:r Bay were 

:first described as the V allenar "series" by 

Brooks, 1 who states: 

The Vallenar series [is] so named from its type exposures 

on Vallenar Bay, at the northern end of Gravina Island. 

The series is composed essentially of limestones and calcareous schists with some black slates. 

Fossils were collected at this locality by 

Brooks in 1901 and determined by Charles 

Schuchert as Devonian. More collections were 

made in 1905 and 1906 by the Wrights and 

E. M. Kindle 2 who report: 

One mile west of Vallenar Bay, Gravina Island.-The.material from this locality, while generally insufficient· for 

specific determination, is much better than that obtained 

·last year (1905) and leaves no doubt as to the Devonian age 

of the beds west of Vallenar Bay. Several specimens of 

Atrypa reticularis are present. This fixes the horizon as 

not later than Carboniferous, while the association of Chonetes cf. manitobensis, Spirijer sp., Proetus sp., and Cyclonemasp. indicate a horizon of Devonian age, probably middle Devonian. 

Some poorly preserved material collected by 

the writer in 1915 was determined by T. W. 

Stanton as probably Devonian. 

The beds of V allenar Bay were correlated by 

Brooks with rocks on Long Island. 3 Middle 

Devonian rocks of similar character occur on 

Clover Bay, on the east coast, and Hunter ·Bay 

and Klakas Inlet, on the west coast of Prince of 

Wales Island and on Hotspur ~sland. 

CARBONIFEROUS ROCKS. 

BEDS INCLUDED. 

The term "Ketchikan series" was applied by 

Brooks 4 to argillaceous and carbonaceous rocks 

with some limestone beds and finely foliated 

slates and phyllites that o~cur on Tong ass N arrows, riear Ketchikan, on Revillagigedo Island, 

and on Cleveland Peninsula. Brooks considered these rocks to be In part Carboniferous and 

in part Mesozoic and suggested that probably 

the limestones· are Carboniferous and the slates 

period of deposition extended even beyond the Carboni£~ 

erous period into the Triassic, especially when the extensive development of Triassic strata to the south in British 

Columbia, as described by G. M. Dawson, is taken into 

consideration. The evidence thus far gathered, however, 

indicates Carboniferous age for the greater portion of these 

crystalline schists and argillites. 

Brooks. noted that the limestones overlie the 

argillites (slate and greenstone) and thus appear 

to be younger. This confusion was due to their 

overturned position, the older beds actually 

overlying the younger ones. 

The assignment of the rocks mapped by 

Brooks as the "Ketchikan series" to both 

Carboniferous and Triassic is in harmony with 

the writer's interpretations. The part of 

Brooks's "Ketchikan series" that stratigraphically underlies the conglomerate and massive 

limestone which in this report are correlated 

with the Upper Triassic 'rocks of Gravina 

Island is here regarded as Carboniferous. 

DISTRIBUTION AND CHARACTER. 

The rocks herein assigned to the Carboniferous are essentially crystalline schists and 

limestone. In areal distribution they occupy 

· a . broad belt along the border of the Coast 

Range, extending from the mouth of Portland 

Canal northwestward for an unJrnown distance. 

In the area under discussion they are restricted 

to a small area on Revillagigedo Island near 

the head of George Arm. The schists make up. 

the greater part of the series. They are evidently the result of contact metamorphism 

induced by the intrusive rocks. An adequate 

description of them would ~equire a detailed 

petrographic study of the rocks in the field 

and an intensive microacopic study, ne~ther of 

which has been made by the writer. The limestone constitutes a relatively small part of the 

series." It occurs in beds 100 feet in maximum 

thickness intercalated with the crystalline 

schists. It is dominantly w.hite and crystalline. 

STRUCTURE ·AND: STRATIGRAPHIC RELATIONS-. 

are Triassic. 

The Wrights 5 state: The Carboniferous rocks. are closely folded 

and contorte_d. Theyocc:upyagreatlydis~urbed In view of the comparatively w~ak paleontologic and 

stratigraphic evidence bearing on the precise age of these belt along the western . border of the Coast 

argillites and crystalline schists, it is 'possible that their Range and form .the overturned. limb of a 

· · ' · syriclinorium in which are involved all the I Brooks, A. H., Preliminary report on the Ketchikan mining district, · . · · • ' 

Alaska: u.s. Geol. survey Prof. Paper 1, p. 42,1902. formatiOns east of Clarenc~ Strait. The other ~ 'Vright, F. E., and C. W~, The Ketcl:iikan and Wrangell mining dis- limb of the syricline comes to the surface on 

tnots, Alaska: u.s. Geol. Survey Bull. 347, p. 50, 1008. h . f a' . I I d a Brpok~, A. H., op. cit., p. 4.3. t e western coast o ravma san . 4Brooks,A.H.,PreliminaryreportontheKetchikanminingdistrict, The base of the Carboniferous schists and 

Alaska: U.S. Geol. Survey Prof. Paper 1, p. 44, 1902. 1 .. - · · ; · · d Th · 1 5 Wright, F. E. and c. w., op. cit.; p. 56. Imestones Is not expose . ey apparent y 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 120 PLATE VIII 

A. WAVE-CUT BENCH, DALL BAY, GRAVINA ISLAND, ALASKA. B. CONGLOMERATE, BLANK INLET, GRAVINA ISLAND. 

,-~ - \,, $ -

:::. ·1 , _ 

--~\ .......... ~' 

-. ' 

C. SLATE AND GRAYWACKE, BLANK INLET. GRAVINA ISLAND. D. ANTICLINE ON VALLENAR BAY. GRAVINA ISLAND. 
r;RAVIN A A~D REVILJ;A~IGEDO ISLANpS, ALASKA. . . . 89 

overlie ~qnglomerate and limestone beds whose 

age is· unknown but which are regarded.· as 

Upper Triassic. The strata at this locality, 

however, n.re believed to be overturned so that 

the normal sequence of ~he beds i~ reversed. 

(See :fig. 12.) 

AGE AND CORRELATION. 

Fossils were collected from the limestone 

near Coon Island at the head of George Arm 

by Mr. Brooks, who states that the many 

crinoid stems suggest that at least the limestones belong to the upper Paleozoic. C. W. 

Wright also collected fossils from George Arm, 

on which E. M. Kin~le reports as follows: 1 

No. 966. Point on southeast side of George Inlet 10 miles 

from its head, Revillagigedo Island.-'l.'he fossils from this 

point comprise only crinoid stems, which, however, are so 

abundant as to make up a large portion of the rock. Crinoid stems can not ordinarily be used for correlation. 

However, th.eir great ahuuda~ce here seems to justify a 

surmise that they very probably represent a Carboniferous 

horizon. Crinoids in such abundance as is shown by these 

This fauna is known to be at but one other point in Alaska 

-Porcupine mining district-wher~ some of the same 

species were obtained last year. This fauna also is entirely dissimilar from those of the Mississippi Valley and 

Appalachian region and finds nearer affinities i~ those of 

western United States and of eastern Europe (Russia). 

These schists and limestones are therefore 

tentatively reg~rded . as late Carboniferous. 

Their relation to the Devonian beds of V allenar 

Bay is not evident, as the two are ~owhere 

known to be in contact. If these schists and 

limestones are correctly correlated ~ith tl1e 

]ate Carboniferous it would appear that there is. 

ln.cking in this region a very .thick section of 

Carboniferous rocks wbj.G~ Btf~ \0dely developed 

on the west coast of fri,t;tpe ... of Wales Island:. 

These include Mi~sis~ipp~an: ·limesto.ne .. a~d. 

cherts, which. are prol;>ably. the equivalent of 

the Lisburne limef?tone, ~nd · Pennsylva~an 

limestones that include Moscovian· and Gschelian faunas. · · · ..,. . 

TRIASSIC ROCKS. 

specimens occur in very few places, if anywhere, outside BEDS INCLUDED. 

of Carboniferous horizons. In the absence of other evidence the horizon represented may be referred tentatively The. term "Gravina series" was :first applied· 

to the Carboniferous. by Brooks 3 to ~as~iv.e conglomerate overlfl,J.n· 

Other collections made by P. S. Smith in by black slates or shales occurring on the sou.th 

1913 contained nothing of determinative value end of Gravina Island: He included in his 

but were considered as probably Paleozoic. mapping of this "series'" the.somewhat siffiil.ar 

No collections were made by the writer, but massive congl~merates il.lld associated black 

the crinoid-bearing beds were observed at a slates and arenac~ous sediments of' the ~est 

number of places. coast, Bostwick I~let, and Blank~ Iclet a~,d 

The:r;e is little doubt of the Carboniferous age suggested its probable extensio~ tq <?th~r: 

of at -least one of the .fossiliferous beds in this places. As a resu}.t of recent investigation~,. 

series of schists and limestones, but their exact how:ever, the sedi~entary rocks of ~ravir},a 

age and stratigraphic positio.n .are much in Island originally defined as the "G-:ravi~ip. 

doubt. Lithologi~ally, except in amount of series" are now known to include two sedi-' 

n1etan1orphism, they resemble the slate and meiJ-tary formatio~s-one of Triassi~ ~ge. ~~<;(. 

limestone <;>f the Porcupine district. The one of Jurassic or Cretaceous age. These hvo · 

slates and limestone beds of the Porcupine dis- sediment~ry formations are associated with 

trict are not fossiliferous, but from closely volcanic roc~s of intermedi~te stratigraphic· 

associated massive limestone beds fossils were position. Brooks first regarded the "G~avina, 

collected which G. H. Girty first doubtfully series" · as Cretaceous and 'co.rrelated it with' 

referred to the lower Carboniferous but later the Queel_l Charlotte series of Vancouver an·d . 

dotol'lnined as upper Carboniferous. Regard- Queeri Charlotte island~, but later he stated· 

ing a similar fauna from Admiralty Island, that its identity with the ''Vancouver series" · 

Gi:rty 2 says: (T~iassic) seemed equally probable. 4 His cor-

~I~he fauna from point at southeast entrance to Pybus relations with both Triassic and Cret~ceous Bay, Adluiralty Island, which also seems to occur at point· formations, made. without ~ny fossils, p~ov~~ on divide between Chapin .Bay ari:d Herring Bay, Admi- · substantially correct: 

ralty Island, is without doubt upper Carbon,iferous in age __________________ ___..::.______ 

and probably cau be designated Pen;no-Carboniferous. 

'Wright, Jt'. E. and C. 'N., op. cit., p. ·55. 

s U. S. Goo!. Survey Bull. 287, p. 143, 1906. 

a Brooks, A. H., Preliminary report on the Ketchikan mining district, 

Alaska: U.S. Geol. Survey Prof. Paper 1, p. 45, 1902. 

• Bropks, A. H., The geography and geology of Alaska: U. S. Geor: 

Survey Prof. Paper 45, p. 226, 1906 

. 0 
9o SHORTER CONTRIBUTIONS TO GENERAL .GEOLOGY, .1918. 

DISTRIBUTION AND CHARACTER. 

The Upper Triassic rocks on Gravina Island 

comprise a gradationally conformable series 

of conglomerates, limestones, sandstones, and 

slates. T~ey are most typically exposed on 

the southwest coast of the island, where they 

occupy a narrow belt that extends from a small 

cove opposite Dall Bay northwestward for 

about 7 miles. Unfossiliferous rocks, presum-

~bly of the same formation, to judge from litholo.gic similarity and structural relations, occupy 

a narrow belt that extends across George Arm 

and Carroll Inlet. 

On Gravina Island the Upper Triassic rocks 

fall naturally into three main divisions-one 

composed essentially. of conglomerate, one 

essentially of limestone, and one of interbedded 

black slate, sandstone, conglomerate, and 

limestone.· These three conformable terranes 

are shown by fossils to be probabiy Upper 

Triassic. Overlying the Upper Triassic sediments, with apparent conformity, are volcanic 

agglomerates and. intercalated sedimentary 

beds which are, at least in part, of Upper 

Jurassic or lower Cretaceous age and possibly 

in part of Upper Triassic age. 

The exposed basal member of the series on 

Gravina Islarid is a coarse conglo~erate that 

extends along the southwest coast of the island 

from Conglomerate Point northwestward to 

Open Bay and occupies three narrow strips 

whose continuity is broken by Fivemile Cove, 

Thompson Cove, and Threemile Cove. The 

conglomerate is a heavily bedded, massive rock. 

T?e boulders are essentially. of angular coarsegrained granite resembling the granite of Annette Island, and the matrix is quartz-feldspar 

sand presumably derived from the same source 

as the boulders. Intercalated with the coarse 

conglomerate are thin beds of sandstone, which 

are composed of the same material as the 

matrix of the conglomerate, and gradational 

beds of grits. Thin beds of fossiliferous limestone and black slate with.pronounced cleavage 

occur sparingly. The congbmerate and intercalated sandstone beds are strongly indurated 

and break with prominent fractures across the 

boulders. 

On a small cove south of Threemile Cove 1 

the conglomerate is finer grained toward the 

top and passes upward into grits, sandstone, 

and slate which are overlain by a large block 

1 Threemile Cove has appeared in t)J.e literature as "cove 3 miles 

north of Dall Head." 

'of fossiliferous massive limestone. There has 

been some movement along this cont~ct, so 

that the relations are confused, but the limestone is apparently above the conglomerate 

and sandstone. On Thompson Cove the conformable relations of the limestone to the conglomerate, sandstone, and slate are more evident, 

although here also there has been some faulting. 

In the upper part of the conglomerate the 

beds are thinner and the material is much finer 

grained. and contains more sandstone, slate, 

and thin beds of limestone, which are conformably overlain by the massive limestone. 

The limestone varies in appearance from 

place to place. On Thompson Cove and Open 

Bay it is a soft gray fossiliferous rock, corals 

being especially abundant. On Threemile 

Cove it is more closely folded, is considerably 

silicified, and weathers out brick-red. The 

limestone here is less fossiliferous, and the fossils are poorly preserved. The greater amount 

of deformation of the limestones on Threemile 

Cove is probably the result of contact metamorphism induced by the intrusive rocks of 

Dall Head. 

The massive limestone is conformably overlain by a great thickness of black slate with 

intercalated beds of conglomerate, sandstone, 

and limestone. These beds crop out along 

the coast of Gravina Island for a distance of 

about 3 miles north of the limestone area and 

extend to the high hills of Dall Ridge north of 

Dall Head. Similar rocks are exposed on 

Bostwick Inlet and Seal Cove and extend northwestward in a belt from 2 to 3 miles wide to 

Vallenar Bay and North Vallenar Point. 

The dominant rocks of this series are blackclay slates having a pronounced cleavage. Intercalated with the slate are thin beds of quartz 

sandstone, quartzite, and conglomeratic sandstone. The limestone beds are not numerous 

but are usually fossiliferous. The interbedded 

limestone layers are about 20 to 30 feet in 

thickness but appear to be lenticular. 

The black slate and associated sediments 

are closely folded, especially on Threemile 

Cove, where the beds are thrown into sharp 

contorted folds. The beds on V allenar Bay 

are much more regular and show none of the 

close folding. 

On Revillagigedo Island associated conglomerate, limestone, schistose slates, and phyllites 

are correlated with the sedimentary series of 

Gravina Island on the basis of similarity of 
GRAVINA AND REVILLAGIGEDO ISLANDS, ALASKA. 91 

lithology and sequence and· stratigraphic and STRUCTURE. 

structural relations. The beds are exposed on ·The Triassic conglomerate, limestone, and 

George. Arm, Carroll Inlet, and Thorne Arm. black slate of the west coast of Gravina Island, 

1"he litho~ogic similarity of these rocks to the' although closely folded, maintain a general 

Triassic rocks of Grav~na. Island is m~rked, strike of about N. 70° W. The beds dip northno~w~t~standing the~ mor~ s?histos~ nature, east and occupy one limb of the synclinorium, 

whiCh IS clue to thmr. proximity to the large which clips ben~ath the volcanic rocks and 

masses of intrusive rocks. The conglom~rate is. comes to the surface in Bostwick Inlet and 

very schistose, and the cobbles are mashed and presumably also on Revillagigedo Island near 

~eformecl. !he)imeston~ is white a~d crystal- the head of George Arm, where the beds are 

lme, and the slates are In part schistose and involved in the overturned limb of the synmight 1nore correctly be .termed phyllites and clinorium. 

schists. Similar slates, phyllites, and schists . 

occur on the north end of Tong ass Narrows. 

These .rocks show different degrees of metamorphism. The most extreme phases occur 

along the borders of the plutonic bodies of 

Revillagigeclo Island, and the amount of metamorphism varies more OI' less directly with its 

nearness to the igneous· rock. On Tong ass 

· Narrows the slates show little metamorphism 

except cleavage and the development of a 

little secondary mica. As the igneous rocks 

are approached the metamorphism becomes 

more noticeable. On Ward Cove the slates 

have a very pronounced schistosity and· contain 

considerable secondary mica and hornblende. 

The most prominent type is a dark-gray rock 

with acicular hornblende crystals a centimeter 

in length, white mica, quartz, and colorless 

garnet in large euhedral crystals. Pyrite is 

locally abundant. Another type is a dark-

'green schist.composecl essentially of hornblende 

and quartz. Garnet is an abundant accessory. 

It occurs in euheclral crystnls partly altered 

to calcite and quartz. Epidote, chlorite, and 

pyrite also occur. 

No fossils have been found in these rocks, 

but on account of their stratigraphic position 

between the Carboniferous rocks of Revillagi- . 

gedo Island and the supposedly Triassic or 

Jm·assic volcanic rocks· of Tong ass Narrows 

and Gravina Island, they appear to occupy 

about the same horizon as the Triassic slates 

and sandstones of Gravina Island. The sequence of this series is also the same as the 

Triassic succession of sedimentary beds of 

Gravina Island-conglomerate, " limestone, 

argillaceous and arenaceous sediments. From 

the present relation of the beds the sequence 

on the two islands appears to be reversed, but 

this is due to the overturned position of the 

section on Revillagigedo Islan~. · 

STRATIGRAPHlC RELATIONS. 0 

The base of the Upper Triassic series of Gravina Island is not visible. The lowest part 

exposed occurs at Threemile and Thompson 

coves, where the actual base of the conglomerate 

is concealed by the water. At Vallenar Bay 

the Triassic rocks overlie Devonian sediments 

'that come to the surface along the axis of an 

anticline. The contact is covered by the 

Quaternary deposits of Vallenar Bay. The 

presence of Devonian pebbles in the conglomerates of Threemile Cove indicates an underlying rock of that age, and on George Arm the 

supposedly Triassic rocks rest upon Carboniferous rocks. A marked unconformity at the 

base of the Upper Triassic rocks is thus evident. 

On Gravina and Revillagigedo islands the 

Triassic rocks are in places conformably overlain by volcanic beds of. Upper Triassic or 

Jurassic age and in places ·unconformably by 

slate and graywacke of Jurassic or Cretaceous 

age. The conglomerate and sandstone of Dall 

Head are invaded by dioritic rocks, presumably 

of Jurassic or Cretaceous age, and are unconformably overlain by Tertiary lavas. 

ORIGIN. 

The Upper Triassic rocks are the products of 

normal deposition and are evidentlyof marine 

origin, as shown by the fauna present in all 

the members. They are believed to represent 

an unbroken period of deposition, but the 

abrupt change from conglomerate to massive 

limestone and black slate with numerous intercalations of limestone, conglomerate, and 

sandstone indicates that the rocks were de-. 

posited under· constantly changing conditions. 

The massive conglomerate was evidently a 

basal formation and was laid down in comparatively shallow water near the shore line 

and ~~rived its material from the products of 
9.~· SHO~TER ·C_ONTRIBU~IO;NS . TO. ~:ENER:AL GEOLOGY, 1918. 

land waste. The :o;rganic -nature of the lime- .ing. fro:p1 the. upper;r;nost part of the Carbon.-. 

st~~e is_cl~_arJy .. proved by the great abundance ,iferou.s or from the Mesozoic. These beds were 

of orgaruc_ i.¢I_h~il;ls, especially corals, which· it : tl;l.u~: doubtfully referred to the Mesozoic for 

co~~~lris. '':r:.4e .· ~chists an~ pJ:yl~tes were' . spwe years, but recent collections have shown 

or~ginally ·slate~ .. ·and s~n~stones·, probably of t4,em to be without much doubt 'I'riassi9 and 

m~r~~e .9rig!~, bu~ have .been changed to their probably Upper Triassic. . 

present condition. PY th~· contact influence of Collections made by Martin and .Overbeck 

the intrusive ro9ks~ , · ·-· · · · from the lin1estone beqs of Tlu·eemile Cove 

AGE AND COJ;tltELATION. occurring beneath the black slate were deter-. 

mined by T. W. Stanton as follows: · 

The age-of these ·rocks is shown by a large 8830 (G. C. M. No.2). Gravina Island,. south arm of "cove 

nuniber .. :of0 fossil: colleetions, made frorri all 3 lniles north of Dall Head." Massive limestone outmembers of the series, to be Triassic, probably crop -fi~ar anchorage behind wooded island.' 

Upper T~i::.t~!;!~,G~·.. -- ··· ;Undetermined corals of Mesozoic type, two or three 

Jrossils ~glle9t~_d l;>y G. Q. Martin and R. M:. · ····.gener~uepr.esented. · 

Overbeck_··. ''froffi·'t.he massive 'conglori:i'erate• at Ostr~a}_.sp... . .· . ':. . · - · · - fseudoip.~lalli,~? ~P .. , ~p.terpal cast. . t~e· e.x.P'1sed 'Qase of. this serief? were d~te~fuiri.ed Arcestes??:· sp0 fragni.(mt; may not even be an amby T. w~- Sta:ri'tol} as·~ol~ow.s; ... . - . . . · · .. monite. .. -~ .. 

· · · · : ,. · : · · Probably TriassiC. 

8&a1 (G. C. M. No. 3). Gravi~a Island near 8~30~ Large ·l~.es~one nodule i~ conglo~era~e·; The whole nodule 8832 (G. C. M. No: 4). Gravina Island, near south foreland. 

·is a nautiloid .. with deeply lobed sut't.U;e,· possibly refer~ · .· ~ ar~ of "cove 3 miles north of Dall Head," near:.conable · to··Cosmoriautilus. On· the back is a ·Rhyncho- tact. with conglomera~e.. · . · · Undeterinined ~.oral frag-~_e.nt· . . ·nella (?). Probably Triassic. . ~ . . . · · Pentacrinus sp:·, segment of column. 8~33"(G. G ... ¥, No. p). GraVIna Island, south arm o~ cov~, .. p b bl T . . · 3 miles· north .. of Dall Head. Near zone .of noduhir . '· · ro a Y nasSlc. . · · · · · · ·. · · .: ··f. ·1··· · t ' 1 m. rat· · Th' 1

·

0

· t app ars. 8834 (G. C. M. No.6). GraVIna Island, north arm of "cove masses o 1mes one 1n congo e e. 1s e · . . . to be Devonian . . a pules north of Dap Head., Mass~ve hmestone in. 

·; . . : , · . .. . . . . reef we~t of cabin. Probably ab9ut 100 feet below 8704. · M;r. Ma.ftrp. s op1n10n, With whiCh the Writer Corals, probably several genera. 

ag~~e~, is that the Triassic conglomerate rests Cassianella sp. 

unconforriuibly upon Devonian rocks, and the My~phoria?? sp. 

Devonian fossils from Threemile Cove were ob- N atlca sp. 

thiried'eitherfrom boulders in the co11glo~erate MuT. r~his?nia? sp. . . . nass1c. 

o!·from unrecog~ized Devonian rocks occurring ,883~ (G. C.· M. No. 7). Gravina Island, near 8834', from 

iri'complex structural relations with the Triassic thin-bedded limestone interbedded with shale about 20 

beas. The· beds on Threerriile and Thompson or 30 feet below 8834. 

co:~i3~ a.re faulted and also closely fold,ed and Corals; several genera represented. 

co_·.·:ht. ort.ed, thus being thr,own into com_ plex Spiriferina? sp. Myophoria? sp. siructural relations.. From the wording of the N atica sp. 

loc"dli.ty description given above it would Turritella? sp. 

appear quite possible that the fossils· were col- Pseudomelania? sp. 

'lected from included masses of limestone in the Tr~chyceras_? sp:, small fragment. 

conglomerate. In 1916 A. H. Bro9ks and t~1e 

writer collected fossils from narrow bands of 

limestone .. definitely interbedded with the conglomerate~ J. B. Reeside reports on thes.e as 

follows: 

9~99 (16 ACh 136). Threemile Cove; Gravina Island. 

Echinoid spi~e, _:possibly of_Cidaris. Age ~mdetermined. 

Fossils were first collected from Threemile · 

Cove in 1906 by 'the W~ights. 1 The exact locality is unc~rta~, but the matrix of the fossiliferous rocks is described as c.alca'reous schist·, 

which is evidently the· siliceous limestone. 

The fauna was regarded by G: H. Girty as com1 Wright, F. E. and C. W., op: cit., p. 52. 

Triassic. 

The following collections made by the writer 

in 1915 from the limestone overlying the massive conglomerate were determined by Mr. 

Stanton: 

9531 (15 4-Ch ll1). V\Test coast o~ Gr~vi_n.a Island. 

2} miles north of Dall Head. 

Echinoid spines. 

Undetermined corals. 

Ostrea? sp. 

Gryphaea'? sp. 

Pecten sp. 

Natica? sp. 

Turritella? sp. . 

Cove 

The fossils in this lot ~r~ poorly preserved an~ . 

mostly fragmentary. They are apparently Mesozoic and may be Triassic. 
GRAVINA AND REVILLAGIQEDO ISLANDS, ALASKA. 93 

15 (ACh 121). Northeast shore of Thompson Cove, Gravina 9532 (15 ACh 113). Threemile Cove, Gravina Island, 300 

Island. yards southeast of north end of cove and about 700 yards 

Corals, genus undetermined. north of 15 ACh 112. Fossils from black slate and limePentacr:inus sp. stone. 

Echinoid spine. · The black slate shows fragmentary specimens of 

Ostrea? sp. Halobia cf. H. superba Mojsisovics, of Upper TriasSolemya? sp. sic age, while the limestone shows imperfect speciTurritella? sp. mens which seem to be referable to Aucella and 

Spiriferina? sp. hence is probably of Upper Jurassic age. 

Probably Triassic. 

9534 (15 ACh 122). Northeast shore of Thompson Cove, 

Gravina Island. 

This lot includes unrletermined corals, Ostrea?, 

Turrjtella?, and undetermined gastropods. Probably Triassic.· 

9535 (15 ACh 123). North shore of Thompson Cove, Gravina 

Island. 

Pecten? sp. 

Gryphaea? sp. 

Tialobia sp. 

Undetermined ammonite. 

Triassic. 

9536 (15 ACh 129). Fivemile Cove, Gravina Island. 

Limestone apparently overlying massive conglomerate. 

Corals, several undetermined genera. 

Bryozoa? 

Pecten sp. 

Purpurina?? sp. 

Undetermined slender gastropod. 

Probably ~riassic. 

9537 (15 ACh 130). Fivemile Cove, Gravina Island. 

Corals, several genera. 

Bryozoa? 

Myophoria sp. 

Purpurina?? sp. 

Turbo? sp. 

Trinssic. 

9538 (15 ACh 132). Fivemile Co:ve, Gravina Island, immediately nQrth of 9537. 

Gryphaea sp. 

Probably Triassic. 

Two lots of fossils collected by P. S. Smith 

frmn the black slate of Threen1ile Cove (8704) 

and also from Fivemile Cove (8705) were subtnitted to J\1r. Stanton, who reported as follows: 

The only fossil species recognized in these two lots is a 

Halob·ia, which is closely related to if riot identical with 

If. superba Mojs.isovics, an Upper Triassic species. The 

rock!s from which these collections came are therefore refen·cd to ~he Triassic. 

The writer n1ade the following c9llections in 

1915 frmn the black slate and interbedded 

litnestone and sandstone beds of Threemile 

Cove, Thon1pson Cove, and Dall Ridge. Stanton reports: 

15 ACh 112. Threemile Cove, Gravina Island, 300 yards 

north of 15 ACh 111. 

' Spiriferina? sp. 

Tialobia? sp. 

Probably Trinssic. 

28288°-19-7 

The limestone and black slate from which 

the fossils regarded as Upper Triassic and 

Upper Jurassic were obtained are apparently 

interbedded. This anomalous occurrence may 

be due to very closely infolded Jurassic 

rocks, but it ·appears· more probable that 

the doubtful Jurassic forms are not· correctly 

identified. 

9533 (15 ACh 115). Thompson Cove, Gravina Island. 

Halobia slates in fault block. 

Cidaris? sp., imprint of surface. 

Halobia ct H. superb a ·Mojsisovics: 

Triassic .. 

15 ACh 124. Dall Ridge, 1 miles north of Dall Head, 

Gravina Island. 

Echinoid spines, etc. 

Probably Trinssic. 

The f~llowillg c9llection was identified by 

J. B. Reeside: 

9900 (16 ACh 137). Threemile Cove, Gravina Island. 

Cerithium? sp., fragment showing part of two 

whorls. 

Isastraea cf. I. profunda Reuss. 

Thamnastraea cf. T. rectilamellosa Winkl. 

Spongiomorpha? sp. 

Hydrozoan, undetermined. 

Natica? sp. 

These forms are apparently of the Upper Triassic 

coral fauna referred by J. P. Smith to the N oric. 

The conglmnerate sandstones near tll.e crest 

of Dall Ridge contain Devonian fossils, but as 

these are fragmentary and occur in pebbles 

they indicate nothing more than the postDevonian age of the rocks. IGrk reports: 

15 ACh 126. Dall Ridge, 4 miles riorth of Dall Head. 

Fragmental fossils apparently occurring as pebbles in conglomerate. At least one of the fossils is 

Devonian. It is a coral, probably Alveolites. 

Black slates and sandstone.s exposed on the 

west coast of Bostwick Inlet are correlated, on 

:structural grounds and lithologic similarity, 

with the upper part of the T~iassic rocks on 

the west coast of the island, but fossils collected 

by different men have served to confuse the 

relations. The fossils listed below were collected in 1914 by J\1artin and Overbeck from 
94 SHORTER CONTRIBUTION~ TO GENERAL GEOLOGY, 1918. 

the west shore of Bostwick Inlet and identified 

by T. W. Stanton: 

8836 (G. C. M. No. 8). Gravina Island, Bostwick Inlet, 

west shore near entrance. From angular nodules in a 

brecciated(?) nodular limestone. 

Terebratula sp. 

Spiriferina? sp. 

Pecten sp. 

Plicatula? sp. 

Cassianella sp. 

Myophoria sp. 

Myophoria or Trigonia sp. 

Nacula sp. 

Astarte? sp. 

Arcestes? sp. 

Triassic. This assemblage suggests the fauna of the 

lower part of the Modin formation in California, 

which was tentatively assigned to the Jurassic. 

Near. this same locality P. S. Smith1 also collected fossils on which Girty reports as follows: 

wick Inlet, which is unknown elsewhere in 

Alaska, may mark a Lower Triassic horizon, 

also unknown in Alaska. lie states: 

As Mr. Girty points out, this ·fauna is entirely unlike 

any other from Alaska. It therefore affords little aid in 

solving the stratigraphic position of the beds on Gravina 

Island. Certain significant deductions, however, suggest 

themselves. In general in southeastern Alaska the known 

Carboniferous rocks are limestones and not lithologically 

similar to the rocks of Gravina Island. The rocks here 

discussed are much less dynamically metamorphosed and 

are less intensely deformed than the known Devonian or 

Carboniferous rocks of the region. Their relation to the 

andesitic agglomerates and flows fits in better with an 

assumed Mesozoic age than with a Paleozoic age. The 

almost uninterrupted succession of beds from a basal (?) 

conglomerate to shales containing unquestioned Triassic 

fossils on the southwestern coast suggests that the doubtfully determined genera from that locality, provisionally 

assigned to the Carboniferous, justify the suggestion made 

by Mr. Girty at that time that they may mark a Triassic 

Three lots from Bostwick Inlet, Gravina Island, contain horizon. No Lower Triassic is known in Alaska. Is it not 

round crinoid stems (13AS170) and a single compressed possible that this fauna from Bostwick Inlet, which is 

pelecypod (13AS169), suggesting the genus Posidonomya. unknown elsewhere in Alaska, fits into this as yet unfilled 

The third lot (13AS171) contains a pelecypo(i fauna inter- gap? 

esting and varied but entirely new to me. As these fossils , 

at best show only the shapes and some of them the sculpture, and as pelecypods of similar external appearance may 

belong to widely different genera, the identifications made 

here are offered with doubt. Though similar doubt tacitly 

surrounds many pelecypod identifications in faunal lists 

and elsewhere, I have expressed it in this case by the use 

of question marks because the age of the whole fauna is 

involved in such uncertainty. In lot 171 five types are 

represented more or less abundantly and by specimens 

more or less good. These are Glossites? cf. G. lingualis, 

Schizodus? cf. S. appressus, Paracyclas? cf. P. ellipticus, 

Crenipecten? cf. C. crenulatus, Elymella? cf. E. nuculoides. 

Besides these, however, there are a good many indeterminate forms, some of which suggest the genera Leda, 

Chonetes??, Pseudomonotis??, Aviculipecten, and Nucula. 

The age of the fauna is quite uncertain. You declined 

for the time being to admit it into the Triassic, and nothing 

resembling it has thus far been brought in from the Alaskan 

Carboniferous. The generic and specific resemblances 

suggested above might indicate a Devonian fauna~ but 

neither has any Devonian fauna related to this been 

obtained from Alaska. The genus Chonetes, if definitely 

present, would at least limit the geologic age to the upper 

Paleozoic, but the specimen is so imperfect that even 

Its reference to the Lower Triassic, however, 

seems improbable, for the fauna is in the upper 

part of the formation, above the position of 

the Iialobia-bearing slates (determined as 

Upper Triassic) and immediately below the 

Upper Jurassic or Lower Cretaceous volcanic 

rocks. Its reference to the Upper Triassic or 

the Lower or Middle Jurassic would be more 

in keeping with the observed relations. 

The term "Vancouver series" was first applied by Dawson 2 to the entire mass of volcanic 

materials and interbedded limestones, flaggy 

argillites, and quartzites that unconformably 

underlie the Cretaceous rocks of Vancouver 

Island. At that time, on the evidence of 

intercalated fossiliferous beds, this series of 

rocks was regarded as largely Triassic, although 

the possibility of its including both Jura<ssic 

and Carboniferous rocks was recognized. The 

"Vancouver series" was later subdivided by 

Clapp,3 who has shown that it is in part Jurassic and possibly also Carboniferous. The Triassic rock<s of Gravina Island are probably the 

equivalent of parts of the u Vancouver series" 

of Vancouver and Queen Charlotte islands. 

the identification as a brachiopod is doubtful. 

Thus the age of this, the best fauna in the collection, 

must for the present remain undesignated. It would be 

highly rash to attempt any definite age determination or 

conclusion for the other lots, containing, as they do, for the 

most part, only crinoid stems (even that being doubtful 

in some cases), though they may tentatively be placed in 

the Paleozoic. 

Regarding . this report Smith suggests that 

this doubtfully determined fauna from Bost1 Notes on the geology of Gravina Island, Alaska: Prof. Paper 95, p. 

103, 1915. 

Triassic rocks are widespread throughout 

Alaska and occur at many places in southe.astern Alaska. Fossils of Upper Triassic age 

s Daw5on, G. M., Canada Geol. Survey Ann. Rept. 1886, p. ioB. a Clapp, C. H., Southern Vancouver Island: Canada· Geol. Survey 

Mem. 13, p. 37, 1912. 
GRAVINA AN~ REVILLAGIGEDO ISLANDS, ALASKA. 95 

hav-o been fmmd on Admiralty, Kupreanof, 

and Screen islands. 

~fartin 1 states that the abundant corals in 

some of these Triassic rocks of Gravina Island 

suggest that they may represent the lower 

Noric coral fauna of iliamna Lake. He considers that the Triassic limestones of southeastern Alaska, ~hich in general are characterized by faunas containing llalobia cf. II. 

superba Mojsisov-ics, correspond at least approximately in position to the Chitistone limestone of the Copper River valley. 

UPPER TRIASSIC OR JURASSIC ROCKS. 

The 1·ocks designated greenstone and slate 

on the map are made up of an interbedded 

series of altered tuffs, flows, and black slates, 

with some intrusives, occurring on Gravina 

and Revillagigedo islands. The greenstones 

and slates overlie the Upper Triassic rocks with 

apparent conformity. On the evid~nce of a 

few fossila found in the intercalated sediments 

and on structural grounds and analogy with 

rocks oi: known age these rocks are regarded as 

Upper Triassic or Jurassic. 

DISTltiBUTION. 

The greenstone and slate occupy three parallel belts on Gravina Island. One extends. 

from South Vallenar Point to Seal Cove, 

another from the east shore of Bostwick Inlet 

to Vallenar Point, and the third along Tongass 

Narrows from Old Indian Town to Gravina 

Point. Northeast of Tongass Narrows similar 

rocks extend from Radio station to Herring 

Bay. 

CHARACTER AND STRATIGRAPHIC RELATIONS. 

The rocks consist essentially of volcanic 

breccias and tuffs with interbedded black 

slates and water-laid :fine-grained tuffaceous 

sediments. Certain green schistose tuffs apparently interbedded with the more massive 

tuffs and breccias n1ay be older infolded rocks, 

and so1ne graywn.ckes and slates may be 

younger infolded rocks. 

'fhe detailed sequence of the yolcanic rocks 

of Gravina Island has not been worked out. 

In general they may be divided into two 

parts-a lower series of purely igneous material, 

mainly coarse pyroclastic rocks and breccias 

I Mo.rtin, G. C., Triassic rocks of Alaska: Geol. Soc. America Bull., vol. 

27, p. 700, 1916. 

and an upper series of mixed water-laid tuffs 

and black slates and limestone, with porphyritic basic rocks of similar composition, evidently partly intrusive and partly explosive .. 

No sharp line separates the two parts, which 

the writer has not differentiated on the geologic map. The black slates pass into green 

fissile tuffs, and these into more massive varieties, so that as a rule a sharp line of contact 

can not be drawn between them. By more 

detailed work the lower purely volcanic material might be separated from the upper mixed 

sedimentary an.d igneous material. The limestone bodies are too small to be shown on a 

map. 

The base of the volcanic rocks is evidently 

the coarse breccia that overlies the Upper Triassic sediments of the west coast of Gravina 

Island. This breccia occupies the southern 

part of Dall Ridge and portions of Califorrna 

Ridge. It is a fine-grained green rock with 

large angular fragments set in a dense matrix 

of the same composition. 

The breccia passes upward into finergrained tuffs, in part at least water-laid material with which are intercalated black slates 

and thin beds of crystalline limestone. Th(} 

black slates are typical clay slates having a 

well-developed cleavage, with bedding planes 

discernible in places. The slates are plainly 

conformable with the green tuffs. 

The black slates and green. bedded tuffs are 

best developed along the north shore of Tongass Narrows from Ketchikan to Mountain. 

Point. The black slates are in places considerably metamorphosed and schistose and 

might more correctly be called phyllites. They 

are closely interbedded with and grade int<> 

fissile green tuffs, both of which are interbedded 

with more massive tuffs. The green tuffs are 

also schistose and in places completely recrystallized. The greater part of the· town of 

Ketchikan stands on rocks of this character, 

and excavations for street building show both 

the blocky and fissile types. The most schistose types are completely recrystallized and 

consist of secondary quartz, feldspar, calcite, 

epidote, and chloritic material. The massive 

types consist essentially of secondary epidote, 

hornblende, chlorite, sericite, and calcite, with 

pyroxene and plagioclase feldspar crystals 

almost entirely replaced by secondary minerals. 
96 SHO~TER CONTRIBUTIONS TO GENERA~ GEOLOGY, 1918. 

The schistose green tuffs refer!ed to by 

Brooks 1 as greenstone schist and by Smith 2 as 

the green schist near Ketchikan, were regarded 

by both as Paleozoic. According to the present 

interpretation of t1le structure of Gravina and 

Revillagigedo islands these tuffs stratigraphically overlie the massive ignec,ms rocks carrying Jurassic fossils and occupy a position near 

the top of the formation. Their schistose namental rocks indicates that they also were 

submarine. . , 

AGE AND CORRELATION. 

The age determination of the greenstone 

an~ slates re~ts upon rather slender paleontologiC foundatiOn. The collections from Bostwick Inlet were submitted to Mr. Stantcn, 

who reports as follows: 

ture is believed to be due to contact meta- 9528 (15 ACh 104). Bostwick Inlet, Gravina Island. 

morphism induced by the intrusive masses of · 9529 (15 ACh 105). Bostwick Inlet, Gravina Isl~nd. 

Revillagigedo Island, as indicated by tl;le in- Aucella sp. 

f 

Probably Upper Jurassic; possibly Lower Cretacrease o schis~osity toward the igneous rocks ceous. 

on the northeast. 9530 (15 ACh 106). Bostwick Inlet, Gravina Island. 

The base of the greenstone and slate series Pecten? sp. 

is evidently the coarse breccia found along the Not sufficient for determining age but probably 

west _coast of Gravina Island. It overlies the from same formation as 9528 and 9529. 

Upper Triassic sediments with apparent con- 1 These fossils were collected from the west 

formity. _ As previously bro~ght out, the coast of Bostwick Inlet about half a mile 

breccia grade~ upward into a m9re dominantly south of the localities from which the. Triassic 

sediment~ry series of green tuffs and black and doubtful collections were made. The 

slates which ~re ·unconformably overlain by fossils occur in sedimentary beds apparently 

conglomerate, slate, and graywacke of Upper interbedded with the. volcanic breccias and 

Jurassic or lower Cretaceous age. overlying. the Triassic sediments, but the 

relations are somewhat obscured by- the. gravel 

STRUCTURE.· covering. 

On Gravina Island the volcanic rocks of . Some correlations with rocks of known age 

Dall Ridge occupy the trough of an, over- ·are suggested. The·greenstone and slate series 

turned syncline, and the other tWO. areas-one !3Xtends more or less COntinuously along the 

extending from Vallenar Point· to Bostwick mainland and adjacent islands of southeastern 

Inlet and the other on Tongass Narrows- Alaska. In the Juneau region the recent 

form the two limbs ~f another . overturned detailed work of Spencer and Eakin shows a 

syncline, the trough of which contains the section similar to that exposed along Tongass 

Upper Jurassic or Lower Cretaceous sedimen- Narrows and adjacent islands, and Brooks, 

tary rocks of Blank Inlet. The-volcanic rocks who has studied both sections, believes that the 

on the northeast shore of Tongass Narrows are black slate and greenstones of Ketchikan 

also believed to be overturned and to overlie should be correlated with the andesitic flows 

stratigraphically the phyllites of Ward Cove an~ ~lack _slates of Juneau, which carry 

and George .Arm and the Carboniferous sehist Triassic fossils. The finding of Upper Triassic 

to the northwest, which seem to overlie the fossils by Spencer and Eakin 3 in the slate and 

volcanic rocks.. greenstone series of Juneau suggests to the 

ORIGIN. writer the possibility that the rocks of Tongass 

The volcanic breccias at the base of the series 

are evidently the product of volcanic explosions. The perfect stratification of much of 

this igneous material and the conformable 

intercalations of slate and limestone show that 

at least portions of it were deposited or collected in water. The pillow-like structure of 

some of. the· flows that occur with the fragNarrows are of similar age~ Smith 4 notes the 

similarity between the volcanic rocks of Gravina Island and the augite melaphyres of the 

region north of Juneau, referred by Knopf 5 

to the Upper Jurassic or Lower Cretaceous 

and. it is not at all unlikely that the uppe; 

portiOn of the slate and greenstone series of 

the Ket?hikan district may be the equivalent 

1 

- • • 8 U.S. Gaol. Survey Thirty-eighth Ann. Rr.pt. p. 90 1917. 

Brooks, A. H., Prehmmary report on the Ketchikan inining district, . 4 Smith, P. s., op. cit., p. 164. ' ' 

A~aska_: U.S. Geol. ~urvey Prof. Paper 1, p. 48,1902.- ·· r 5 Knopf, Adolph, The Eagle River region, southeastern Alaska· 

• Sllllth, P. S., op Cit., P· 100. U.S. Gaol. Sm:vey Bull. 502, p. 18, 1912. . 
GRAVINA. AND. REVILLAGIGEDO ISLANDS, ALASKA. 97 

of the volcanic rocks associated with. the stone contains· igneous material..- The Maude 

Berners formation. The slate and greenstone formation· is regarded on fossil· eviden·ce ·as 

of the Ketchikan district may thus be corre- Upper Triassic and Lower Jur!Lssic. 

latcd with both the Triassic and Jurassic rocks ':fhe conformably overlying Yakouil formaof the Juneau region. tion ~onsists of water-laid agglomerates and 

Hocks of greater . value for purposes of tuffs, conglomerates, lavas, and possibly intrucorrelation occur on Vancouver arid Queen sives. Fossils contained in the intercalated 

Charlotte islands. The ''Vancouver series," sediments indicate a· Jurassic age, suggesting 

first- defined by Dawson as 1'riassic, was· later. correlation with the Tuxedni sandstone '(Midsubdivided by Clapp 1 on the basis of distribu- dle Jurassic). 

tion, lithology, and structure into the Nitmat 'The correlation of the lower part of the valformation, Vancouver volcanics, Sutton· for- canic rocks of .Gravina Island· with the Vanmation, Sicker series, and Metchosin volcanics. couver volcanics and the upper part of the 

I-Ie uses the term ''Vancouver group" in Maude formation is suggested. The upper part 

place o:f ''Vanc·ouver series" as used by Daw- of the volcanic rocks .of Gravina Island may 

sou. The Nitinat formation is made up of be the equivalent, at le~st in part, of the Sicker 

highly altered calcareous sediments and is series and the Yakoun formation. The age 

regarded as Jurassic or Triassic ( ~). The of tl?-e Gravina Island volcanic rocks is qy no 

·vancouver volcanics are composed largely of means certain. It !s not at all unlikely that 

volcanic materials with interbedded sediments .. -they cont~in qoth 'Priassic and _Jurassic rocks 

On the evidence of fossils collected from the and . possibly some infolded Paleozoic rocks 

intercuJated limestone beds of the Sutton for- also. 

mation the Vancouver volcanics are regarded 

by Clapp as lowermost Jurassic. The Jurassic UPPER JURASSIC OR LOWER CRETACEOUS ROCKS. • 

age of these rocks~ however, is not· accepted 

by Martin, 2 who considers that the fossil 

·evidence is not conclusive and that the Sutton 

limestone fauna may with equal confidence be 

called Upper Triassic. The Sicker series is 

made up of metamorphic, chiefly schistose 

sedimentary and volcanic rocks, with intrusive 

porphyrites. The stratigru.phic relation of this 

'"series" to the "Vancouver group" of which 

it 'forms a part is not certain, but it is believed 

to occur above the Vancouver volcanics. 

DISTRIBUTION AND CHARACTER. 

A formation consisting ess6ntially of interbedded. conglomerate, graywacke, and black 

slate exposed along a wedge-shaped strip 

extending from Blank Inlet to the northeast 

coast of Gravina Island (see Pl. VIII, Band 0) 

is determined on fossil evidence to be Upper 

Jurassic or Lower Cretaceous, and similar 

rocks just northwest of Ward Cove are correlated with this formation. 

On Gi·aham The conglomerate does not appear to he the Island, one of the 'Queen Charlotte group, the "Vancouver group" was sub- basal member ~ut ~ccurs at inter:als throughdivided by Ma~Kenzie 3 into the l\1aude forma- out the formatiOn In~erbedded With the graytion, referred to the Lower Jurassic and·possi- wa~ke and slate. !tIS compose~ of rather fine 

bly in part to the Triassic, and the Y akoun I grained pe?ble~ With a few boulde_rs -~s much 

formation, of Middle Jurassic age. The l\1aude as a foot In diameter.. The matnx Is essenfornlation is composed of a lower part, made tially a graywacke but contains a considerable 

up of banded slaty and flaggy argillites, in amount of igneous rock fragments. The 

places carbonaceous, and an upper part of pebbles and cobbles are mostly igneous and 

feldspathic sandstones. Partly crystalline bi- resemble the volcanic rocks of Gravina Island. 

tu:minous massive limestones are provisionally Pebbles of dioritic rocks resembling the pluclassed with the 1\!Iaude formation. Near the tonic rbcks· of the Coast Range also occur. 

top of the formation, where it begins to grade No members of this formation are known to 

into the overlying Yakoun formation, the sand- be of igneous origin, although both matrix 

1 ctupp, c. H., op cit., p. 37. and cobbles of some of the conglomerates 9 Murtin, a. c., op. cit., P· 709. contain so great an amount of igneous material a MucKonzio, J. D., Geology of Graham Island, B. C.: Canada Geol. 

survOIY Mem. ss, p. 39, 1916. that they resemble agglomerates. 
'98 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

The conglomerate passes by increasing fineness and decrease of igneous material into 

typical-looking. graywacke with angular slate 

fragments. Microscopic examination of the 

graywacke shows it to consist essentially of 

quartz and feldspar grains with angular fragments of slate and decomposed particles of 

dioritic rocks, hornblende, pyroxene, and 

epidote. Flakes of biotite may be secondary, 

but no marked schistosity has developed. 

The slates are very fissile black clay slates 

and are closely interbedded with the graywacke members. The slates have a marked 

cleavage. (See Pl. VIII, 0.) 

STRATIGRAPHIC RELATIONS. 

These Upper Jurassic or Lower Cretaceous 

beds overlie the volcanic rocks of Gravina Island· 

described above and/ regarded as Triassic or 

Jurassic, but in most places the relations are 

rather obscure. On the northeast· shore of 

Bostwick Inlet near the entrance the slates 

and graywacke overlie the eroded surface of 

o the volcanic rocks with marked unconformity. 

On the northeast shore of Gravina Island conglomerates and graywacke overlie the volcanic 

rocks without apparent angular unconformity. 

The conglomerate and graywac~e of Ward 

Cove are noticeably unconformable upon the 

black phyllite that has been correlated with 

the Upper Triassic !"ocks. 

STRUCTURE. 

The conglomerate, slate, and graywacke beds 

of Blank Inlet occupy the trough of an overturned syncline in which are also involved the 

volcanic rocks of Gravina Island, which actually 

overlie them on the east shore of Blank Inlet. 

ORIGIN. 

These Upp.er Jurassic .or Lower Cretaceous 

conglomerates, graywackes, and slates are the 

products of normal deposition in a shallow sea. 

The constantly changing character of the deposits indicates corresponding changes of con.:. 

ditions during their deposition. The materials 

of the rocks were apparently derived in part 

from the volcanic rocks of Gravina Island near 

by and in part froJp. the surrounding regions. 

AGE AND CORRELATION. 

The age determination of the slates and 

graywackes of Blank Inlet rests on a single 

fossil collection from which only one form was 

identified. Mr. Stanton reports: 

9527 (15 ACh 99). Blank Inlet, 1! miles nor~h of Blank 

Point, Gravina Island. 

Belemnites sp. 

Jurassic or Lower Cretaceous. 

Smith 1 correlated the conglomerates and 

other sediments on the west coast of Gravina 

Island with these somewhat similar ones on 

Blank Inlet. However, besides the fossil 

evidence which now shows that the two are 

distinct, there are very marked differences in 

the lithology. The conglomerates of Threemile 

Cove are composed essentially of a peculiar 

type of igneous rock that was not noted on 

Blank Inlet, where the conglomerates contain 

a great amount of greenstones and dioritic 

rocks similar to the intrusives of the Coast 

Range, types neither of which was observed 

in the ·conglomerate of the west coast. The 

sedimentary beds of both Bostwick Inlet and 

the west coast contain beds of siliceous sandstone and quartzite but no appreciable amount 

of graywacke. On Blank Inlet the reverse is 

true; the arenaceous beds are dominantly 

graywacke, and pure quartzose beds are lacking. Structural differences are also very apparent. The conglomerate of Blank Inlet is 

considerably sheared; the rocks of the west 

coast are massive. This might appear to indicate a greater age for the rocks of' Blank Inlet 

but the greater amount of deformation is no 

doubt due to the difference in composition of 

the rocks, the soft agglomeratic material being 

much more easily affected than the granite. 

It is a noticeable fact that the few diorite 

boulders in the conglomerate of Blank Inlet 

have withstood the deformation. 

The rockS of the Queen Charlotte series, 

with which these beds of conglomerate, slate, 

and graywacke on Gravina Island were at first 

correlated, are now determined as Upper Cretaceous 2 and are thus younger than any 

known rocks of Gravina Island. The conglomerate, slate, and graywacke of Blank Inlet 

are possibly the equivalent ·of the Berners 

formation of Eagle River, the conglomerate, 

graywacke, and slate of Admiralty Island and 

other places in southeastern Alaska, and the 

Valdez group of Prince William Sound. 

1 Smith, P. S., op. cit., p. 104. 

2 Ma.cKenzie, J. D., op. cit., p. 65. 
GRAVINA AND REVILLAGIGEDO ISLANDS, ALASKA. 99 

TERTIARY ROCKS. 

The only rocks of Tertiary age within the 

area. consist of rhyolite, which occurs on the 

peaks of Dall Head and extends from Thompson Cove nearly to Seal Cove. It is a lightgray dense rock composed essentially of quartz 

and feldspar. o It overlies unconformably the 

granite and greenstones of Dall Head and has 

not shared in the mineralization of the under.-

lying rocks. It was regarded by the Wrights 

and Smith as Tertiary. 

QUATERNARY ROCKS. 

GLACIAL DEPOSITS. 

DISTRlBUTION AND CHARACTER. 

The most recent sediments are the glacial 

deposits. Rocks of this character are not 

abundant but have been found at one place on 

Gravina Island. About half a mile northwest 

of the cabin at the head of Dall Bay is a small 

exposure of glacial material about 80 feet 

above sea level. The outcrop is concealed on 

all sides by vegetation. The exposed base 

contains about 2 feet of glacial till and blue 

clay and is overlain by stratified beds of glacial 

gravel about 5 or 6 feet thick. Fossils occur 

in both the blue clay and the stratified gravel. 

AGE AND CORRELATION. 

A s1nall collection of fossils from the glacial 

deposits was subn1itted to W.- H. Dall, who 

reports: 

I have examined the material from Dall Bay, Gravina 

· Isl.and. The material is a "boulder clay" which disintegrates in water, and when it is strained off the fossils remain in a clean condition. Near the Treadwell m'ine 

opposite Juneau the same formation extends to an altitude 

of 200 feet. The species contained in Mr. Chapin's collection are as follows: 

Cylichnella n. sp. 

Bela violacea Mighels. 

Colus sp., fragment. 

Cardium (Cerastoderma) ciliatum Fabricius. 

Axinopsis viridis Dall. 

Macoma calcarea Gmelin. 

Saxicava arctica Linne. 

Mya intermedia Dall. 

Balanus sp., fragment. 

The assembly ·naturally indicates the colder 

climate associated with the period of glaciation. 

These fossiliferous deposits occur about 80 

feet above high tide, a position that indicates 

n.n uplift of the land since the glacial epoch. 

Corroborative proof of a recent uplift is found 

in the elevated wave-cut benches found in this 

vicinity. That part of Gravina Island south of 

Dall Head, the bold promontory that marks 

the south end of the highlands of the island, is 

a flat plain (Pl. VIII, A). This and similar 

features on Annette Island and at other places 

near by ·are regarded as wave-cut benches. 

Smaller features of the same character are lowlying, flat benches along the coast, some a few 

feet above high tide and others only partly 

above water. The higher benches are forested 

and dissected by erosion; but others near the 

water level are bare of vegetation and apparently have been· only recently ·uplifted, and it 

is not at all :unlikely that this emergence has 

continued to the present time. As the benches 

are developed only locally, however, it is probable that the uplift was of a differential character and that some parts of the region are sinking below sea level and others are rising, owing 

to the warping nature of the n1~vement. 

MARINE GRAVELS. 

During the period in. which the fossiliferous 

deposits of Dall Bay stood at sea level the low 

depression that connects Vallenar Bay and 

Bostwick Inlet was evidently in large part 

flooded if not wholly covered. It is thus safe 

to assume that the gravels that mantle the 

floor of this '' through'' valley are largely 

marine, although partly reworked by later 

stream action. The valley floor is covered by 

vegetation which hides the deposits. 

INTRUSIVE ROCKS. 

The intrusive rocks of Dall Head were not 

examined in detail by the writer. On the west 

coast of Gravina Island they are apparently 

dioritic in composition and along the contact 

with ·the sediments are gneissoid. This structure is regarded as purely cataclastic; the 

gneissoid effect is commonly noted in the diorites at other places in the Ketchikan district 

and is not regarded as evidence of an older 

gneiss. On the extreme southern point of 

Gravina Island, however, Smith noted gneisses 

which he regards as Paleozoic, intruded by 

igneous rocks. He states: 1 

At this place they consist of highly metamorphic gneisses 

and amphibolites which have been intruded by igneous 

rocks. Undoubtedly the older rocks have been metamorphosed locally by the younger intrusives, but apparently 

1 Smith, P. S., op. cit., p. 97. 
100 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 19·18. 

they were considerably metamorphosed dynamically before 

they were intruded. No definite determination of the age 

of the gneisses and amphibolites has been made. Judged 

by their physical character they seem to be much older 

than any of the known late Paleozoic rocks. Although 

their aspect may be due in large measure to the contact 

effects produced in proximity to the large intrusive masses, 

the impression gained in the. field, and not dispelled by 

later investigations in the office, is that those rocks are 

probably at least as old as the middle or earlier part of the 

Paleozoic era. 

The relation of the old gneisses and amphibolites to the 

other sedimentary rocks of the region is indefinite, because 

they occupy only a small area at the extreme end of the 

island and are surrounded on all sides by sea or by a large 

area of younger igneous rock. No other rocks on Gravina 

Island are correlated with these rocks near Dall Head. 

The great abundance of coarse angular 

blocks of granite occurring in the Upper Triassic conglomerate suggests a near-by land mass 

of this rock. The gneisses noted above 1nay 

be a remnant of this old land mass, but if so 

the granite must be locally metamorphosed, 

for the cobbles of the conglomerate are massive 

and have suffered little metamorphism. As 

previously stated, the material of the conglomerate is lithologically similar to the granite of 

Annette Island and is su,pposedly from a stock 

of similar composition. 

The intrusives of Dall Bay and Seal Cove are 

granites and associated pegmatites or alaskites. 

These are composed essentially of quartz and 

orthoclase with a subordinate amount of muscovite and secondary sericite. They range in 

texture from medium-grained holocrystalline 

rocks to fine-grained aphanitic <and porphyritic 

phases. They are evidently the equivalent of 

similar rocks occurring at several places on 

Prince of Wales Island and other localities. 

Wherever the relations were observed the 

granite has been found to be later than the 

quartz diorite and associated intrusives of the 

Coast Range, and is probably Cretaceous. The 

granite and quartz diorite of Gravina Island 

have not been separated on the map. 

The intrusive rocks of Revillagigedo Island 

are quartz diorites and ·associated types and 

are to be correlated with the intrusives of the 

Coast Range. They occur as batholithic 

masses cutting diagonally across the sedimentary formations. They are regarded as Middle 

or Upper Jurassic, as the conglomerates of 

Upper Jurassic or Cretaceous age contain 

many boulders of similar rock, which is lacking 

in the earlier conglomerates. 
TWO LAMPROPHYRE DIKES NEAR SANTAQUIN AND MOUNT NEBO, UTAH. 

By G. lf· LouGHLIN. 

INTRODUCTION. 

No description of lamprophyre dikes in Utah 

has heretofore been published/ and this paper 

is presented as an addition to the petrology of 

the State. The two dikes here described are 

on the west slope of the Wasatch. Mountains, 

near Santaquin and Mount N ebo, and were 

noted by the writer in 1912, while he was en:.. 

gaged in a reconnaissance of the ore deposits of 

central Utah. 

LOCAL. GEOLOGY. 

STRATIGRAPHY. 

The steep western front· of the Wasatch 

Mountains in the Santaquin and Mount N ebo 

region exposes rocks of pre-Cambrian~ Paleozoic, and Tertiary age, whose relations are 

c01nplicated by overthrust and block faulting. 2 

(See fig. 13.) 

The pre-Cambrian is represented by reddish 

gneissoid. granite with pegmatite veins and 

included bodies of schist, exposed for 2 miles or 

more along the lower west· slope of the main 

range southeast of Santaquin. This granite is 

overlain unconformably by Cambrian quartzite, 

dipping 28° E., which does not appear to be 

over 800 feet thick (aneroid measurement). 

rrhe quartzite is prominent along the middle 

west slope' east of Santaquin and about 5 miles 

northeast of Mona. It passes upward into 

Cambrian shale, which corresponds to the 

Ophir formation to the north and west, and 

this is followed by a great thickness of limestones, the lower beds of which are probably 

• 13. S. Butler has informed the writer that he.has noted several biotite 

lamprophyro dikes during his recent detailed studies or the Cottonwood 

and Park City area in Utah. 

. 2 Loughlin, 0. J<,., Reconnaissance in tho southern Wasatch Moun· 

,tt\ins,'Utah: J'our. Oe'ology, vol. 21, pp. 447-451, 1913. 

of Cambrian age and the higher beds certainly 

of Mississippian age. The upper Mississippian 

includes thin quartzite beds intercalated with 

limestone and shale. The limestones form the 

greater part of the range throughout the region, 

occupying most of the summit areas and upper 

western slopes and extending down to the west 

base of the range in the Mount Nebo mining 

district northeast of Mona. 

The Tertiary rocks include coarse reddish 

conglomerate and concretionary limestone, 

which rest unconformably upon the Mississippian. They veneer the low ridges south and 

southwest of Santaquin and are very extensive 

on the east slope of the main range. These 

rocks are overlain by a coarse latite or andesite breccia, most of whose outcrops have been 

reduced to aggregates of loose cobbles. 

DIKE ROCKS. 

The only intrusive rocks noted in the region 

are the lamprophyre dikes that form the subject of this paper. The northern dike is southeast of Santaquin, on the Black Balsam claim. 

It cuts pre-Cambrian granite, is 3 feet thick, 

trends northeastward, and dips about 70° SE. 

It is closely paralleled for part of its course by 

a vein of calcite and fluorite which contains a 

little chalcopyrite, galena, and corresponding 

oxidation minerals. The southern dike is south 

of the mouth of Bear Canyon, northeast of 

Mona, on the property worked by the Eureka 

Leasing & Mining Co. in 1912. It cuts Mississippian limestone, is 4 feet wide, strikes N. 

45°-50° E., and has a vertical dip. 

There is no local evidence by which these 

dikes can be correlated with other igneous 

rocks. From their petrographic character, 

however, and their lack of deformation, it is 

101 
102 SHORTER CONTRIBUTIONS T'O GENERAL GEOLOGY, 1918. 

assumed that they represent a late stage of the I by granodiorite and quartz diorite to the 

Tertiary volcanic period, which is well repre- north in the Cottonwood-American Fork resented by latites ~or andesites on Long Ridge, gion. 2 Lamprophyre dikes in the last-named 

SE===~==~==~==~====~O=====================JSMJLES Contour interval500 feet 

:Datum is mean sea level 

FIGURE 13.-Geologic map of the Santaquin and Mount Nebo region, Utah. JR, pre-Cambrian granite; £,Cambrian quartzite; Cm, MississippianandcarlierUmestones; T, Tertiaryconglomerateand volcanic rocks; L,lampropbyredikes. ·List ofmines: 1, Union Chief; 2, Santaquin 

Chief and Santaquin King; 3, Big Nebo; 4, Eva and Nebo Highland; 5, Spider; 6, Freddie Lode (Eureka Leasing Co.). 

west of Mona; by rhyolites, latites, and mon- region, according to Butler, are the latest of the 

zonite farther west, in the Tintic district/ and intrusive rocks. 

'Lindgren, Waldemar, and Loughlin, G. F., Geology and ore deposits 

of the Tin tic mining district, Utah: U. S. Geol. Survey Prof. Paper 107, 

pp. 42-75 (in press). 

2 Butler, B. S., and Loughlin, G. F., A reconnaissance of the Cottonwood-American Fork mining region, Utah: U.S. Geol. Survey Bull. 620, 

pp. 174-177, 1916. . 
LAMPROPHYR.E DIKES NEAR SANTAQUIN AND MOUNT NEBO, UTAH. 103 

STRUCTURE. 

The attitude of the strata is for the most 

part homoclinal, with a prevailing dip of about 

30° E., but some folds with steep to vertical 

·dips are prominent east and northeast of Mona. 

megascopic mineral, forming irregular scales 

and tablets 3 millimeters or less in diameter. 

These phenocrysts constitute about 20 per cent 

of the rock and give it the characteristic luster 

of lamprophyre. Alteration products of olivine, consisting largely of calcite in small 

thinly scattel'ed spots, are visible on close inspection of the dike near Santaquin. The application of dilute hy9.rochloric acid produces 

brisk effervescence in both rocks. 

MICROSCOPIC CHARACTER. 

NORTHERN DIKE. 

The most striking structural features of the 

region have been produced by overthrust and 

block faulting. The overthrusts are exposed, 

though not very clearly, east and south of 

.Sa'ntaquin, near the north and south ends of 

the pre-Cambrian granite area; also along the 

west base of the range about 5 miles northeast 

of Mona. At all these places :Mississippian 

limestone is overridden by Cambrian quartzite. 

'The overthrust northeast of Mona c1early ante- The northern dike, as seen in thin section, 

dates the block faulting, as shown in figure 13. consists of a prevailingly glassy groundmass 

·The relation of the overthrusts to local folding 'Crowded with· phenocrysts of augite, biotite 

is not clear. They may be synchronous with olivine, and magnetite and minute crystals of 

·or later than the folding, which elsewhere in apatite. Phenocrysts 0.5 to 1 millimeter in 

·utah is assigned to post-Jurassic time but diameter constitute about 25 per cent of the 

-clearly antedates the intrusions of monzonite rock. Feldspar is present only in the groundand related rocks with which ore deposits are mass. The feldspar and glass form less than 

genetically connected. The writer's investi- 50 per cent of the rock. Calcite, fibrous monogations in the Cottonwood-American Fork 1 and clinic amphibole, and chalcedonic quartz are 

·west Tintic 2 districts, however, have proved alteration products. 

that the overthrusts in those districts are older Augite is· the most abw1dant microscopic 

than the igneous intrusions and any accom- phenocryst, making up about 35 per cent of 

panying deformations, which are probably of the rock. It forms typically twinned prisearly Tertiary age, and he provisionally corre- matic automorphic grains. The main part has 

lates the overthrusts in the Santaquin and an extinction angle (r td~) between 45° and 

Mount Nebo region with those in the districts 50°, whereas that of a narrow marginal zone is 

·mentioned. about 5o greater. These angles do not accord 

The block faulting is marked by norma] with Rosenbusch's statement a. that the py-

:faults of northward and east-northeastward roxenes of lamprophyres are of the diopsidic 

trends, most of which coincide in position with variety, and this is one characteristic in which 

·canyons. These faults were formed by the the tw9 dikes are exceptional. The augite is 

disturbances that caused the main uplift of the very free from alteration. 

"Wasatch Mountains and the ranges of the Oli.vi~e. in hypautomo~p~ic crystals as much 

·Great Basin. They are later than the volcanic as 2 millimeters long ong1nally formed about 

breccia and presumably later than the two· 3 per cent of the rock. These crystals are now 

lamprophyre dikes and· the ore deposits of the mostly altered to aggregates of calcite and a 

region, but there is no means of comparing the .finely fibrous to platy monoclinic amphibole . 

.age of the dikes with any local faulting. A f~w crystals are replaced by serpentine and 

calcite. No secondary magnetite accompanies 

THE DIKES. 

MEGASCOPIC CHARACTER. 

The rocks are dark gray to black, dense, and 

porphyritic. Biotite is the only conspicuous 

1 I .. oughlln, G. F., op. cit., pp. 440-443. Butler, B.S., and Loughlin, 

G. 1~., A reconnaissance of the Cottonwood-American Fork mining 

rl'glon, Utah: U.S. Geol. Survey Bull. 620, pp. 178-179, 1916. 

2 Butler, D. S., and Loughlin, G. F., Ore deposits of Utah: U. S. 

Geol. Survey Prof. Paper 111 (in press). 

the alteration products .. 

Biotite forms many irregular to automorphic 

brown grains and tablets, most of them less 

than 0.5 millimeter long but some more than 

1 millimeter. The larger phenocrysts have 

borders that are darker bl'own than the main 

pal't, a common feature in the biotite of lampro3 Rosenbusch, H., Elemente der Gestcinslehrc, p. 233, 1906. 
104 SHOR.TER CONTRIBUTIONS TO GENERAL. a·EOLOGY, 1918. 

phyres. All the· biotite is of distinctly later In this rock biotite is more abundant than 

growth than augite and oliVine.· ·As a whole it augite, constituting about 20 per cent of the 

is free from alteration, but a "few of the larger section. It ·forms hypautomorphic crystals, 

phenocrysts contain a little calci.te. · · the largest of which are not much over 1 milliMagnetite is present in fine grains, mostly of meter in diameter. Its pleochroism, as a 

square outline, ·thickly scattered throughout whole, is from medium brown to white. The 

the section. It is for the most part of later borders of the crystals are darker brown than 

growth than the three minerals just described. the main part. The central parts of some crysN o inclusions of it are found in the augite or tals are ·olive-colored. Alteration products, 

olivine except along their margins, and very which are very scarce, include calcite and 

few are found in the biotite. chlorite. The biotite crystallized later than 

Apatite forms many small typical prisms. the augite. 

They _appear to be mostly inclosed in biotite, Augite forms hypautomorphic grains, none 

but many in the groundmass may have been more than 1· millimeter long. The more 

overlopked, owing to their close resemblance to prominent grains constitute about 5 per cent 

the smallest augite crystals in transmitteq of the rock; Some grains show a little alteralight. · No pyrite was identified in this section, tion to calcite, and some have fringes and veinalthough the chemical analysis signifies the lets of a very finely fibrous mineral, probably 

presence of 0.24 per cent. amphibole. · 

Feldspar is present in places, forming a poiki- Apatite forms prominent though small typilitic matrix for the minerals already described. cal prisms, the largest 0.2 millimeter long. 

It occurs in divergent or radiating aggregates, Magnetite is present only as fine grains of 

as shown by its extinction, but each aggregate square outline, some of which are altered to 

appears to be a homogeneous crystal in other hematite. 

respects. Its mean index of refraction is a The radiating feldspar which makes up the 

little above 1.52 and, together with the di- groundmass has a mean index of refraction a 

verging habit, suggests albite. The isotropic little above 1.52 and a large ax1al angle and is 

groundmass has an index of refraction a little optically positive. These properties all indiabove 1.51. In a few places it forms small cate albite. No orthoclase was recognized. 

rounded areas free from phenocrysts and re- Little or no isotropic material is present in the 

sembling an isotropic mineral such as analcite; groundmass. 

but in some of these areas incipient growths of Pyrite forms a few irregul.ar grains as much 

feldspar are recognizable, and no gelatinization as 0.3 millimeter in diameter, which may be 

was obtained by evaporat.ion ~th hydro- impregnations of the groundmass rather than 

chloric acid. There is no sharp boundary primary crystals. 

between these rounded areas and the rest of Calcite, besides impregnating augite ~nd 

the groundmass. biotite, forms a few small round to irregular 

aggregates impregnating the groundmass. Some 

Chalcedonic quartz fornis a few small irregu- of these are accompanied by chalcedonic quartz 

lar aggregates in the groundmass and is closely and smne by pyrite. 

associ a ted with calcite. · . 

SOUTHERN DIKE. 

The. southern dike, as seen in thin section, 

consists of phenocrysts of biotite, augite, 

apatite, and magnetite in a groundmass of 

feldspar which has a distinctly diverging or 

radiating habit. Alteration~products are pyrite, calcite, chalcedonic quartz, chlorite, and 

hematite. 

CHEMICAL COMPOSITION. 

The chemical composition of the northern 

(Santaquin) dike is shown by the analysis in 

column 1 of the accompanying table, which 

includes also the most closely corresponding 

analyses given by W ashington. 1 

I Washington, H. S., Chemical analyses of igneous rocks: U.S. Geol. 

Survey Prof. Paper 14, pp. 315-317, 1903. A second edition (Prof. Paper 

99) of this work has been issued since the completion of the present 

paper. 
LAMPROPHYRE DIKES NEAR. SANTAQUIN ANDOMOUNT N:EBO, :UTAH. 105 

Chemical analyses of lmnprophyre from Santaquin, Utah, and rocks of similar composition. 

1 2 3 4 ·5 6 7 8 9 10 ll 12 

------1·---1·-------------------1----1-----------

SiO;.. . . . . 45. 59 45. 47 46. 67 48. 36 51. 68 48. 73 52. 09 48. 66 44. 27 46. 47 49. 45 50. 79 

Al:Pa. . . . 12. 02 13. 07 12. 64 12. 42 14. 07 ll. 92 11. 93 12. 36 10. 73 15. 97 14. 41 15. 26 

Fe20 3 •••• 3. 84 6. 72 6.13 5. 25 4. 71 4. 79 1. 84 3. OS 3. 63 5. 97 3. 39 3. 29 

FeO. .. . . . 5. 05 12. 43 10. 17 2. 48 4. 57 1 4. 56 7. 11 5. 86 · 5. 87 4. 27 5. 01 5. 54 

MgO..... 7. 09 2. 80 5. 64 9. 36 7. 72 5. 93 12.48 . 8. 09 13.05 5. 87 8. 26 6. 33 

CaO. . . . . 10. 21 6. 79 11. 48 8. 65 6. 65 9. 24 7. 84 9. 97 10. 80 10. 54 6. 73 5. 73 

N a;~_0. . . . 1. 82 · 2. 04 1. 64 1. 46 2. 45 2. 62 2. 04 2. 71 1. 07 1. 69 2. 54 3. 12 

K2u...... 3. 90 3. 36 2. 31 3. 97 4. 16 2. 47 3. 01 5. 15 4. 43 4. 83 4. 69 2. 79 

~~~~8~:::: ~:~~ ... ~--~~----~--~: .... ~--~: .... ~--~~----~--~~--- .... ~~.} 1.46 3.23 2.32 2.43 2.74 

~~d~: :::: i: ~i :::::::: :::::::: ... i." is .... i." os. t ~~ : i~ .... :97 .... i." 37 .... i." 33. · 1J~ i: g~ Zr02 ••••• None ........................................................................................ . P>?01 ..... 1.33 .52 .74 .84 .72 .32 .34 1.07 .83 .73 1.12 .35 

.M.nu..... . 16 . 21 . 19 . 13 Trace. . 36 . 15 . 13 . 06 . 01 . . 13 . 07 

BaO..... . 20 . . . . . . . . . . . . . . . . . 29 ........ Trace. . . . . . . . . . 40 . 48 ....................... . SrO...... .16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 09 . 18 ....................... . s.... . . . . . . 13 . . . . . . . . . . . . . . . . . . . . . . . . . 13 . 34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .••.... 

Cr,03 ••••• Notdet. . 28 . 34 Trace. . . . . . . . . . . . . . . . . ·. 0

107 _· ·. _-·_. .. · ·-. ·_ -_ .· _· .· ·_ ·. _· .·'.· .. · ·.. · ·_· _· .· _· .. · ·.· .· ·. · __ ·j_· .. · · .· .· .· .·•· NfO .................................................... . Cl....................... . . . . . . . . . . . . . . . . . . . . . . . . .11 ............................................... . Li20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Trace. Trace. . .............................................. . 

Sum .... 100.31 

Specific 

99. 85 100. 49 

2. 331 2. 703 

99. 93 100. 03 100. 05 100. 24 100. 00 100: 00 100. 00 100. 00 100. 00 

gravity. a 2. 755 2.94 

a Apparent specific gravity. The apparent specific gravity of the southern (Mona) dike is 2. 680. 

1. Albite ininette, Black Balsam claim, Santaquin, Utah. .George Steiger, analyst. . 2, 3. Basalt, Assab, near Massowa, Abyssinia. Ricciardi, L .. , Soc. geol. italiana Boll.~ vol. 5, p. 59, 1886. 

4. Absarokite, Clarks Fork, Yellowstone National Park. Iddings, J.P., Jour. Geology, vol. 3, p. 938, 1895; U.S. 

Geol. Survey Mon. 32, pt·. 2, p. 329, 1899. · · · 5. Absarokite, Two Oce~n Pass, Yellowston~ National Park. Iddings, J. P., U. S. Geol. Survey Mon. 32, pt. 2, 

p. 329, 1899. . 6. Kersantite, Big Horn Pass, Yellowstone National Park. Iddings, J. P., U. S. Geol. Survey Mon. 32; pt. 2, 

p. 70, 1899. . - ' 

7. Kentallenite, Glen Shira, Argyllshire, Scotland. Hill, J. B., and Kynaston, H., Geol. Soc. London Quart. 

Jour., vol. 56, p. 537, 1900. · · .. ' · 

8. Average shonkinite= Daly, R. A., Am. Acad. Arts and Sci. Proc., vol. 45, p. 228, 1910. 

9. Average missourite. Daly, R. A., op. cit., p. 229. 

10. Average leucite basalt. Daly, R. A., op. cit., p. 229. 

11. Average minette. Daly, R. A., op. cit., p. 233. 

12. Average kersantite. Daly, ·R.· A., op: cit., p. 233. 

The noteworthy features of this analysis are 

low Si02 and relatively high alkalies, with K20 

in excess of N a20, which class the rock with 

alkaline varieties rather than normal basalt; 

also the high content of H20, 002, Ti02, and 

P 20 5 • The :H20 + is only in part accounted 

for by biotite and the fibrous amphibole to 

which olivine is altered, and the remainder is 

evidently present in the isotropic groundmass, 

partly in stnall bubble inclusions and partly 

in solid solution. 002 is present in calcite, 

which was introduced either at the close of 

consolidation or somewhat later, at the time 

of ore deposition. The Ti02 is definitely referred to fine rutile needles in biotite and is 

doubtless present as a minor component of 

biotite; augite, and magnetite. The fact that 

the finely powdered rock is almost entirely 

picked up by a weak hand magnet is proof that 

little or no free ilmenite is present. The high 

P20 5 is attributable to abundant apatite, 

which is a characteristic feature of lamprophyres and certain other rocks of similar 

chemical composition. 

Apparent discrepancies between the analysis 

and the mineral composition (mode) of the rock 

are the high OaO (about 6.5 per cent available 

for silicates), in contrast to the absence of· 

calcic plagioclase, an.d the relatively high K20, 

in contrast to the absence of recognizable· 

orthoclase. In the calculation of the mode;· 

however, the OaO is found to be just sufficient 
106 SHORTER CONT~IBUTIONS TO GENERAL GEOLOGY, 1918. 

to satisfy augite. The K20 in excess of that 

required by biotite evidently belongs to the 

glassy groundmass. · 

The difference between the norm and mode 

is shown below. The orthoclase in the norm 

includes the large quantity of K20 actually 

present in biotite, the albite includes the small 

quantity of N a20 in augite, and the anorthite 

includes much of the CaO and all of the Al20 3 

in augite. The diopside and hypersthene and 

part of the olivine, magnetite, and ilmenite in 

the norm are actually present in augite and 

biotite. 

Calculated mineral composition of lamprophyre dike at Santaquin, Utah. · Norm. 

Orthoclase. . . . . . . . . . 22. 80 

Albite........... . . . . 15. 20 

Anorthite ........... 13. 34 

Diopside ............ 14. 73 

Hypersthene........ 8. 85 

Olivine............. 3. 69 

Magnetite........... 5. 57 

Ilmenite............. 3. 19 

Apatite ............ , 3. 02 

Pyrite............... . 24 

Calcite.............. 4. 30 

Water ( + ). . . . . . . . . . 3. 59 

Water (-). . . . . . . . . . 1. 64 

Mode. 

Orthoclase molecule 1 11. 12 

Albite ............... 12. 05 

Anorthite ........... None. 

Augite .............. 35. 04 

Biotite....... . . . . . . . 21. 27 

Olivine... . . . . . . . . . . 1. 04 

Magnetite........... 2. 78 

Ilmenite............. . 91 

Apatite............. 3. 02 

Pyrite~.............. . 24 

Calcite.............. 4. 30 

Chalcedony.......... 3. 90 

Water ( +) unassigned. . . . . . . . . . . . . 2. 83 

Water(-) .......... 1. 64 

As no analyses of the augite or biotite were 

made, the calculation of the mode is only 

approximate. The assumed composition of 

these two minerals is based on analyses of 

augites and biotites from rocks that are 

similar in composition to the Santaquin 

lamprophyre.2 According to this assumption 

the CaO not present in apatite and calcite 

is exactly the amount required by the augite, 

a condition perfectly in accord with the 

optical character of the augite and the only 

recognizable feldspar, albite. The absence of 

modal anorthite causes the ratios of AI20 3 

to K20 (1.9) in biotite and of A120 3 to CaO 

(0.30) in augite to be higher than the average 

for these minerals, but no higher than in some 

of the analyses tabulated by Cross, Iddings, 

Pirsson, and Washington.2 

The low percentage of olivine in the mode 

compared to that estimated in thin section 

is doubtless due to small errors in the assumed 

1 In glassy groundmass. . . 

2Cross, Whitman, Iddings, J.P., Pirsson, L. V., and Washington, 

H. s., Quantitative classification of igneous rocks, tables 12 and 14, 

1903. . 

MgO and FeO contents of biotite and augite. 

The rather high percentage of chalcedony is. 

attributed to similar errors in the assignment 

of silica. 

Further evidence to confirm some of the 

foregoing statements was afforded by treating 

the rock with strong hydrochloric acid and 

evaporating to dryness. The constituents dissolved are shown in the second column bel~w. 

Partial analyses of constituents of lamprophyre dikes soluble 

in hydrochloric acid. 

-

Dike at Santaquin. 

Dike at 

Per Mona.: 

cent in Soluble Differ- Soluble com- in HOI. ence. in HOI. 

plete 

analysis. 

Al 2 0 3+P20s ......... 13.35 10. 13 3.22 4. 10 

Fe203 ••••••••••••••• 3.84 7.42 ········ 5.31 

FeO ................. 5.05 ........ ......... . ........ MgO ................ 7.09 4.51 2.58 4.22 

CaO .................. 10.21 5. 41 4.80 5.52 

Ti02 ................ 1.67 . 95 . 72 . 51 

C02 ............... 1. 91 1. 91 . 00 . ......... 

In the Santaquin dike' there is only about 1.9· 

per cent soluble CaO in excess of that in calcite 

and apatite, and this may as well have ·come 

from slight corrosion of augite as from any 

undetected sodic plagioclase. The soluble 

magnesia is mainly that derived from olivine 

and biotite; the iron from· olivine, biotite, and 

magnetite; the titanic oxide from biotite and 

magnetite. The alumina is derived largely 

from biotite, but the proportion can not be 

told without determining the soluble alkalies. 

The soluble MgO and CaO indicate ·roughly the 

ratio in augite, which is only slightly less than. 

that assumed in the calculation of the mode. 

Microscopic examination of the insoluble residue showed it to consist mostly of augite and -

scales of isotropic silica left by biotite, with 

small amounts of albite, fibrous amphibole, 

and glassy groundmass. 

The soluble portion of the dike near Mona. 

agrees well with that of the Santaquin dike as 

regards MgO and CaO. Its lower content of 

Al20 3 and Fe20 8 is due in part to the incomplete decomposition of biotite, shown by microscopic examination of the residue, and perhaps 

in part to the greater insolubility of its thor-· 

oughly crystallized feldspathic groundmass. 
LAMPROPHYR.E DIKES NEAR SANTAQUIN AND MOUNT NEBO, UTAH. 107 

CLASSIFICATION. 

According to the quantitative classification 

tho Santaquin dike is designated by the coordinates III.5.3.3 (kentallenose). The excess of 

K~O over· N a20 is only a little lower than that 

of 11!.5.3.2 (absarokose). According to its 

mode, it belongs to the minette-kersantite 

group of lamprophyres.· It differs from typical 

minette and kersantite, however, in possessing 

a largely isotropic groundmass and in this respect resembles monchiquite or analcite basalt; 

but the isotropic material has too high an index 

of refraction for analcite, is not readily soluble, 

and does not gelatinize in hydrochloric acid. 

The rock differs further from minette in containing no recognizable orthoclase or anorthoclase, although its mode shows that one or both 

of these minerals would appear if crystallization 

were completed. It differs more markedly 

from kersantite in the absence of a conspicuous 

amount of anorthite molecule in the feldspar 

and is best designated by the name vitrophyric 

"albite minette." The name "albite minette" 

is equnlly applicable to the dike near Mona. 

In chemical composition the Santaquin dike 

differs considerably from the minettes represented in tJ:e superior analyses tabulated by 

Washington.1 These are designated in thequantitretive system by 1!.5.2.3 (monzonose), II.5.2.4 

(akerose), and 11.5.3.2 (not named). They differ from the Santaquin· rock in having higher 

Si02 andA120 3 , lower Fe20 9, FeO, and CaO, and 

two of the threehaveloviTer MgO and higher N a20. 

Of the minettes analyzred since the publication 

of Washington's t~bles in 1903, a rock de-

·' scribed by Ransome 2 ~13 lower than the Santaquin rock in Si02 and Al20 9 and higher in K20, 

Ti02, and especially P 20 5 , corresponding to the 

coordinates 11!.6.1.2 (washingtonose)~ Another minette, described by Cross,3 resembles 

this one more closely than the Santaquin rock. 

Of the analyzed minettes described by Daly,4 

two are designated monzonose and one 

I1I.5.2.2 (prowersose).· The latter, an olivineaugite minette, agrees with the Santaquin rock 

· rather closely in percentages of Si02 , Al20 3 , 

Na20, ~d K20, and in having a glassy ground1 WMhington, H. S., op. cit., pp. 255, 263, 265. 

D llansomo, P. IJ., An apatitic minetto from northeMtern Washlngton: 

Am. Jour. Sci., 4th scr., vol. 26, pp. 33i-339, 1908. 

a Cross, Whitman, Dike rocks of tho Apishapa quadrangle, Colo.: 

U.S. Oeol. Survey Prof. Paper 90, pp. 18-20, 1915. 

• Daly, :n.. A., Opology of tho Nortb American Cordillera at tpo fortyninth pamllol: Canada Goo!. Survey Mem. 38, pp. 306-312, 1912. 

mass. A lamprophyre between minette and 

kersantite, described by . Schrader,5 is designated by the coordinates II.5.3.3 (shoshonose). 

These differences in classification show that the 

relatively few rocks sufficiently similar in mineral composition· to be classed as minette vary 

considerably in relative amounts of chemical 

constituents. 

There is closer agreement . between the 

Santaquin dike and three of the four inferior 

analyses of nlinette tabulated by Washington, 6 

although these show considerably more Al20 3 • 

Compared with Daly's average of 10 analyses 

of minette 7 (column 12,- p. 105) the analysis 

of the Santaquin rock is rather low in Si02 and 

Al20 3 , about normal in Fe20 9 and MgO, high 

in CaO, and rather low in alkalies, though 

similar in the N a20-K20 ratio. High II20 and 

P20 5 are characteristic of several minettes, as 

is high Ti02 to a less extent. 

One analysis of altered kersantite (column 6, 

p. 105) is very similar to that of the Santaquin 

rock except in the ratio of N a20 to K20 and 

in low P20 5 • Most analyses of kersantite, 

however, are higher in Si02 and Al20 3 and lower 

in iron oxides MgO and Ca0.8 

SIMILAR ANALYSES OF OTHER ROCKS. 

Analyse's 2, 3, 4, 5, and 7 in the table on 

page 105 represent other rocks that in some 

respects agree more closely with the Santaquin 

rock than the minettes and kersantites whose 

analyses are given. With the exception of 

Nos. 2 and 3, which are .termed basalt, the rocks 

represented by these analyses are the uncommon absarokite and kentallenite. All except 

No. 4 (absarokose) belong to the subrang kentallenose. The Santaquin rock differs from the 

absarokites in its abundance of biotite and from 

both absarokite and kentallenite in its lack of 

calcic plagioclase. 

Although single analyses of shonkinite differ 

in various ways from· that of the Santaquin 

rock, falling in groups 1!.6.2.3, 11!.6.1.1, and 

1II.6.2.3 of the quantitative system, Daly's 

average analysis of shonkinite (column 8) is 

5 Schmder, F. C., Mineral depositsofthe Cerbat Range, Black Mountains, and Grand Wash Cliffs, Mohave County, Ariz.: U.S. Geol. Survey 

Bull. 397, pp. 32-33, 1909. 

o Washington, H. S., op. cit., p. 397. 

1 Daly, R. A., Average chemical compositions of igneous rock types; 

Am. Acad. Arts and Sci. Proc., vol. 45, p. 233, 1910. 

a WMhington, H. S., op. cit., pp. 227, 251, 259, 265, 269, 271, 281,315, 

317, 411,413. 
108 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

very similar, as are his average analyses of 

missourite and leucite basalt.1 The similarity 

of the minettes of the Highwood Mountains 

to the shonkinites of the same region was 

pointed out by Pirs$on.2 The relatively low 

content of water, especially H;O +, in shonkinites may be attributed in part to its escape 

during relatively prolonged crystallization as 

well as to freedom from alteration. 

regards ratio of feldspar,. though high in fernie 

minerals. 

The isolation of the Santaquin dike froin 

other intrusive rocks prevents more than general speculation regarding its origin, which may 

be attributed, first, to a concentration of fen1ic 

constituents and normative calcic plagioclase 

in a monzonite magma; second, to conditions 

that caused the crystallization of abundant 

biotite and aluminous augite instead of less 

CORRELATION AND GENESIS. aluminou~ mafic minerals and calcic plagioclase: 

Minettes and kersantites are· generally re- It may be assumed, in accordance with Bowen's 

garded as mafic products, complementary to hypothesis,5 that at some stage in the period of 

aplites, of the differentiation of granitic and moU:zonitic Intrusions and eruptions parts of 

dioritic magmas and are found closely associ- the magma undergoing gravitative differentiaated with large intrusive masses of these rocks. tion became enriched in alkalies, ,water, and 

The nearest mass of post-Cambrian granite or other volatile constituents, which both ingranodiorite. to Santaquin and Mona is about 35 creased fluidity and lowered the temperatures 

miles to the north, in the Cottonwood and of crystallization. Fur.~her differentiation was 

American Fork mining region/ and the only thus promoted, and separation of the heavier 

other intrusive mass within an equal distance constituents continued. These constituents 

is the monzonite stock of the Tintic mining dis- may have been redissolved to some extent by 

trict, 18 miles to the west. 4 The fact that the sinking to a depth where the temperature was 

.dike near Mona cuts Carboniferous limestone high enough, thus forming a basic submagma 

precludes correlation with the pre-Cambrian /l'elat~~ely high in alkalies and water. Whether 

granite of the Santaquin district. Correlation or not this happened, final cryst,allization took, 

of the dikes with certain intrusive stocks is place as follows: Olivine crystallized until the. 

therefore impossible. As the Cottonwood and temperature became too low for it to exist in 

Tin tic stocks, above mentioned, were intruded equilib~ium with the magma; then, instead of 

in Tertiary time, and as the extensive sheets of hypersthene, diopside, and calcic plagioclase, 

lavas in central Utah were erupted in Tertiary the more complex mineral, augite, formed. 

time, it is inferred that the two dikes .also are Although augite contains very little water, the 

of Tertiary age. fact that it does not crystallize from dry fusions 

The volcanic breccia in the Sari~aquin district indicates that water and other volatile constituis of latitic or andesitic character, as are the ents of the magma may have been the factors 

greater part of the v~~Danic rocks to the west that determined its crystallization. The zonal. c 

as far as the Tintic district. The only rhyo- character of the augite, showing an increase in 

lites of the region are closely related to the ·content of alumina as it grew, is of interest in. 

monzonite and latite of the Tintic district in view of the absence of the anorthite molecule 

both occurrence and composition. It seems in th~ feldspar of the rock. At still lower ten1-·. 

probable, therefore, that the two minettes perature biotite, a hydrous mineral that probunder discussion are 'genetically related to a ably contains fluorine, crystallized, perhaps 

monzonitic magma represented· by the latite overlapping the period of later augite in the 

breccias and flows of the region. The norm of groundmass to some ext.ent. After the larger 

the Santaquin dike (p. 106) is monzonitic as biotite crystals had nearly attained their 

1Daly,R.A.,op.cit.,pp.22S,229. growth, n1agnetite crystals begin to forn1, but .. 2 Pirsson, L. v., Petrography and geologY, of the igneous rocks of the the magma solidified before they c~uld attain 

Highwood Mountains, Mont.: U.S. G~ol. Survey. Bull. 237,pp. 145-146, 

, 1905. · any considerable size. a Butler, B. s., and Loughlin, G. F., A reconnaissance of the Cotton- The position of apatite in the order of crys- wood-American Fork mining region, Utah: U. S. Geol. Survey Bull. 

620, pp. 175-176,1916. tallization is not so de:fini te as that of any of the 4 Lindgren, Waldemar, and Loughlin, G. F., Geology and ore deposits 

of the Tintic mining district, Utah: U.S. Geol. Survey Prof: Paper 107, r. Bowen, N. L., The later stages of the evolution of the igneous rocks:. 

pp. 64-69 (in press); · Jour. Geology, supplement to vol. 23, No.8, pp. 41-61, 1915. 
LAMPROPHYRE DIKES NEAR SANTAQUIN AND MOUNT NEBO, UTAH. 109 

other minerals, owing to the small size of its zation. Olivine is evidently unst~le in their 

crystals. They are clearly older than the large presence, even at high temperatures. Other 

biotite crystals but are not found inclosed in minerals or glass in equilibrium with them at 

olivine or augite. high temperatures are subject to attack by 

Crystallization of feldspar, partial in the San- them at low temperatures, and the long time 

taquin dike and complete in the Mona dike, since consolidation, supplemented by dynamic 

n1arked the final stage of consolidation. Con- disturbances that caused fracturing, would 

siderable of the water and other volatile matter favor hydration and carbonatization. The 

not entering into biotite was retained in the presence of metalliferous deposits in contact 

rock, either as minute fluidal inclusions or dis- with or close by the Santaquin and. Mona dikes 

solved in the glass groundmass. The retention leaves the source of water and carbon dioxide 

of water and other volatile matter may be an in their alteration products in doubt, but the 

ilnportant factor in rendering lamprophyres suggestion may be worthy of consideration in 

especially subject to hydration and carbonati- the study of other lamprophyres. 

28288°-19-8 
• 

't 
RELATIONS OF LATE PALEOZOIC AND EARLY MESOZOIC FORMATIONS 

OF SOUTHWES'TERN MONTANA AND ADJACENT PARTS OF WYOMING. 

By D. DALE CONDIT. 

SUMMARY OF CONCLUSIONS. 

The object of this paper is twofold-to present evidence found in southwestern Montana 

concerning the great Jurassic base-leveling and 

its bearing on the solution of certain stratigraphic problems Involving late Paleozoic, 

Triassic, and Jurassic formations, and to set 

forth the relations of those formations to beds 

in western Wyoming. The conclusions briefly 

stnnmarized are as follows: 

Prior to the encroachment of the sea from 

the northwest in late Jurassic time prolonged 

erosion and base-leveling occurred over much 

of the Rocky Mountain region. From the 

Idaho State line near Yellowstone National 

Park northward to the vicinity of Helena the 

erosion surface thus produced truncates beds 

of Triassic and Carboniferous age, through a 

stratigraphic range of about 1,000 feet. 

·The Quadrant quar~zite at the type locality 

in the northwestern part of Yellowstone Park 

is approximately equivalent to the Amsden 

and Tensleep formations in Wyoming. The 

Park City (Pennsyhranian and Permian), Dinwoody (Lower Triassic), and Chugwater (largely 

Triassic) of the Wyoming. section are in part 

represented by the Teton formation of Yellowstone Park. The quartzitic cherty basal beds 

of the Teton, containing the phosphate rock, 

are equivalent to the Phosphoria formation of 

Idaho, which corresponds to the upper part of 

the Park City formation. In western Montana north of latitude 45° 30' the overlying 

Triassic shaly limestone and red shale were removed by the Jurassic eros~ on and the Ellis 

formation (Upper Jurassic) rests on the pe,rtly 

eroded Phosphoria formation. 

FIELD WORK. 

The information set forth in this paper was 

obtained by the writer during the seasons of 

1913, 1915, and 1916. The first two years 

were spent in detailed mapping of the Permian 

phosphate beds along the northeast ~lope of the 

Wind River Mountains and throughout the 

Owl Creek Mountains of Wyoming. A reconnaissance trip was also made on both the east 

and west slopes of the Big I-Iorn Mountains. 

In 1916 a reconnaissance examination occupying about three months was made in Montana 

from Helena south to Yellowstone Park and 

west to longitude 112°, and later in the same 

season a visit was made to exposures in the 

vicinity of Cody, Wyo. Nearly all the outcrops in Wyoming represented on the accompanying map (Pl. IX) except those near the · 

Idaho State line were visited, and also practically all those in the. Montana area. 

FORMATIONS IN SOUTHWESTERN MONTANA 

DISCUSSED IN THIS PAPER. 

The Madison limestone, of Mississippian age, 

which ranges in thickness from 200 to 2,500 feet 

in different parts of Montana, Idaho, and Wyoming, forms an unmistakable unit throughout 

the region and a convenient datum in the study 

of the less constant higher beds. Its slightly 

uneven surface is in places capped by conglomerate made up of pebbles of the Madison 

limestone in a sandy matrix. No generalized 

section of beds above the Madison that is representative of all of southwestern Montana can 

be made, and therefore each formation will be 

described briefly in turn and illustrated by 

stratigraphic sections measured at a number of 

localities. 

QUADRANT QUARTZITE. 

The term Quadrant was introduced by 

Peale 1 to designate a formation consisting of 

150 feet of cherty limestones in .the upper 

part and 200 feet of red limestones below, 

overlying the Madison limestone in the vicinity 

J Peale, A. C., U.S. Geol. Survey Bull. 110, pp. 39-43, pls. 1, 4, 1893. 

Ill 

0 
0 

112 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

·of Three Forks, Mont. The names for the defines the limits of the Quadrant ( ~) and 

Paleozoic formations in the Three Forks area Phosphoria formations. as applied in that 

were stated by Peale 1 to have been determined area. 

"after consultation witli the. members of There has been considerable uncertainty 

Mr. Arnold Hague's division." The stra.ta ·concerning the age of the' Quadrant quartzite. 

to which the name Quadrant was applied Peale's studies in the Three Forks quadrangle 

were therefore doubtless correlated with the yielded fossils of Mississippian and Pennsylstrata, mostly quartzitic sandstone, found on vanian age. Collections of fossils made years 

Quadrant Mountain, in the northwestern part ago by Weed and others northeast of the Three 

of Yellowstone Park, for which Arnold Hague Forks area were found to contain Mississippian 

and W. H. Weed, who surveyed the park be- ·forms, and more recent collections northwest 

tween the years 1883 and 1893, had ·selected of the Three Forks area, within and near the 

the name Quadrant quartzite. The publica- Philipsburg quadrangle, have yielded Penntion of the Yellowstone Park folio, with four sylvanian forms. Field work in 1916 showed 

geologic maps, was delayed until .1896. In that the typical Quadrant in the Yellowstone 

1894, however~· the name Quadrant quartzite Park, as described by Weed in Monograph 32, 

was again used, by Weed,2 for the rocks included representatives. of both the upper 

overlying the Madison limestone and under- Mississippian and the Pennsylvanian. 

lying the Ellis formation in the Livingston The Quadrant generally consists of three 

quadrangle, Mont., which doubtless were re- parts. The basal member is chiefly sandy 

gatded as equivalent to the typical Quadrant red shale, slightly calcareous, containing few 

quartzite of the Yellowstone Park. Since recognizable marine fossils. This red-shale 

1896 the name has been extensively used for member is only a few feet thick along the 

strata in many parts of western Montana Idaho State line but thickens northward to 

supposed to be equivalent-to those at the type ·about 150 feet near Bozeman. Over the red 

locality. shale is more or less limestone and carbonPeale did not give any description of the aceous shale, absent locally but present in 

formatl.on. at the type locality, and the first widely separated localities and containing abunpublished section of the rocks of Quadrant dant fossils, which are believed by G. H. Girty 

Mountain is that measured by Weeds and probably to denote early Pennsylvanian age. 

quoted ' on page 117 of this ·report. It will At the west boundary of Yellowstone Park 

be noted that the overlying cherty quartzitic this limestone. is less than 50 feet thick and 

beds described as the Phosphoria (Permian) sparingly fossiliferous, but it thickens westin this paper are included by Weed in the ward to 250 feet in the Snow crest Range,· 

Teton formation. Although the Teton beda where it is rich in fossils. At Lombard, about 

of (he Yellowstone Park region are also present 75 miles northeast of the Snowcrest Range, 

in the south third of the Three Forks quad- it is nearly as prominent and equally fossilrangle, they were mapped· as a part of the Ellis iferous, but at intervening points it is generally 

(Jurassic) in the Three Forks folio, except thin and contains poorly preserved fossils. 

that the lower cherty quartzitic portion The limestone member is overlain by 100 to 

(Phosphoria) was considered a part of the 400 feet of quartzitic sandstone interbedded 

underlying Quadrant. The reference of the · with a less amount o"f sandy dolomitic limelower part of the Teton to the Quadrant has stone and thin layers of smooth-textured 

been followed in all the geologic folios pub- argillaceous limestone, more or less cherty and 

lished for areas in western Montana, including co;~~~~c::~:so~f th~og~aa;:~~r::di~o=~=t the Philipsburg.4 Pardee,5 however, in a places a little more than 300 feet, but from 

recent report on the Philipsburg region, .. the Gravelly Mountains west to the Snow1 Idem, p. 14. crest Mountains the thickness increases from 2 Weed, w: H., u.s. Geol. Survey Geol. Atlas, Livingston folio (No. about 500 to nearly 1,000 feet. The formal), 1894. . 

au. s. Geol. Survey Mon. 32,.pt. 2, p. 34,1899. tion also thickens northeastward from Lom4u. s. Geol. Survey Geol. Atlas, Philipsburg folio (No. 196), 1915. bard, a point on Missouri River about 35 miles 5 Pardee, J. T.,The Garrison and Philipsburg phosphate fields, Mont.: 

u.s. Geol. Survey Bull. 640, pp. 2o6-211, 1917. northwest of Bozeman. 
U. S. GEOLOGICAL SURVEY 

Point where stratigraphic section was 

measured. Number refers to section 

on Plate X. 

1 

Scale 1,ooo,ooo 

6 o 6 12 1a 24 30 Miles 1 

~==~~C===~~~==~-a 

1918 

Base from 1:1 ,OOO,OOO·scale maps of 

Montana, Wyoming, and Idaho 

Compiled in 1913 

MAP SHOWING DISTRIBUTION OF PHOSPHORIA FORMATION IN MONTANA 

AND EMBAR FORMATION IN WYOMING 

PROFESSIONAL PAPER 120 PLATE IX 

r· 

i 

Geology by D. Dale Condit 
• 

PALEOZOIC AND MESOZOIC, FORMATIONS OF ;MONTANA AND WYOMING. 113 

PHOSPHORIA FORMATION. Lingulidiscina utahensis, together ~ith fos~il 

· bones. In some places the phosphatiy matenal 

The Quaclrant proper is ov-erlain ?Y 100 t.o appears as a resinous brown substance, forming 

250 feet ~of dark-gray cherty quartzite, layms a cement for the quartz sandstone. At 30 toand ropy masses of nodular chert and shale, 60 feet above the base of the Phosphoria occur 

with one or more beds of pho~phate rock. The · other phosphatic beds consis~~g of one .or 

sequence is regarded as equivalent to par~ of more layers of gray to black oolitic phosphorite 

the Park City formation of Utah and Wyomm~, and perhaps a few feet of dark shale overlain by 

but more nearly equivalent to the Phosphona chert either in thin wavy layers or as nodular 

formation of Idaho, as was recognized in 1913 masses mixed in a:n irregular manner with 

by Richards 1 and.later by Stone ~nd Bo~ine? brownish .quartzitic. sandstone. At irregu~ar 

in whose report the name was first pubhs~ed intervals in the sandstone there are pecuhar 

for those beds in Montana. Peale,3 in mapp~g distorted cylindrical· columns of lighter-colored 

the geology. of the Three Forks quadrangle, In- sandstone 1 to 4 inches in diameter, perpenchided the Phosphoria beds as a part of .th~ dicular, or nearly so,. to the bedding planes. 

Quadrant, ap.d he has hem~ followed by Calkms Both the shale and the phosphate beds ~re 

in mapping the Pllilipsburg quad~a~gle. W e~d lacking a short di$tance northeast of a line 

and others, 5 

· ho'Yever, included these beds m drawn from Helena to th~ north:west corner of 

the Teton formation of the Yellowstone Park yellowstone Park. The uppermost beds of the. 

reO'ion which comprises beds ranging in. age Phosphoria contain poorly preserved brachifr~m 1

}ate Pennsylvanian to Triassic, and opod shells and fish bones, probably of PerforminO' three diss~ilar lithologic units. The mian age. 

group~g is somewh~t sim~ar to .. tha~ of the 

Embar formation of Wyommg, which mcludes TETON FORMATION. 

Pennsyhranian and Permian limestone and The Teton formati<;>n, as defined by Weed for 

Triassic shale. . : yellowstone Park, included the rocks now 

Th~ plane of contact,between the P~osp~oria named Phosphoria formation, and the overlyand Quadrant pi·oper is not e3:sily dra~n In all in()' Triassic brown shaly limestone and red 

places, for the reason that ther~, is no mar~ed ~a~dy shale. The brown limestone is urimischange in the lithology of the beds.; T~e line takably related to the Dinwoody formation of 

of division is commonly.inar~edby a f~w mches western Wyoming. This relation was suspected 

of conglomerate and a· nonpe:sisten.t be~ .of by Blackwelder,6 who states that the lower part 

phosphate rock, apparently of clast~c ongm. of the Teton formation is probably equivalent 

It is suspected that these beds denote an un- to the Embar of Wyoming. The overlying red 

conformity. ·.·.·~he ove~·lying r~ck is dark-gr~y shale. is in part equivalent to the Chugwater 

cherty qu~r~zi'te with scattered pho.sphonte. formation of Wyoming and probably to the 

granule.s, .. cliffer~~ ?hiefly in color.fro~ ~he.pu:er Thaynes limestone of .Idaho. The part of the 

quartzitic sand~tone be~ow, whiCh Is. pmki~h Teton be.ds overlying the Phosphoria. is apgray, ~ross-bedded,_ and intercalated With argil- proximately 800 feet . thick along the Idaho 

laceous cr.eamy limestone. State line west of Yellowstone Park, but as 

The .Phosphoria is notably. siliceous, being shown by figure 14 this part was. beveled by 

either cherty or quartzitic almost throughou~ .. · the Jurassic erosion and completely removed 

In Y ellowstoJ?.e Pin·k an~l to the west along and: north of latitude 45° 30' both west and east· of 

near the Idaho State line the irreg~lar layer· of Yellowstone Park. ' . 

phospha:te rock at the b~se is :made up of. frag- Fossils of Triassic age· are plentiful in the 

ments of phosph~tized shells of the brachiopod shaly brown limestone. No fossils were found 

I Richards, R. w., tmpublished manuscript. in the red shales, _b_ut abov~ them is lo~ally a 

2Stone,n.. w.,andBonine,C.A.,TheEllistonphosphatefield,Mont.: bed. of richly fossiliferous limestone whiCh at 

u s Oool. Survey Bull. 580, p. 375, 1914. · t 1 th Idaho State line south of ~Peale, A. c., u. s. Geol. Survey Geol. Atlas, 'l'hree Forks folio' one pmn a ong e . . (No. 24), 1896. ·· Red Rock Lakes was found . to contmn a 4 Calkins, F. 0}, and Emmons, W. H., U.S. Gool. Survey Geol. A,tlas, pleurotomarioid gastropod possibly identical 

Philipsburg folio (No. 196), 1915. . .- ' 

G Hague, Arnold, Iddings, J.P., Weed, W. H., Walcott, C. D., G1rty, 

fth Y 11 t 1 G. H., Stanton, T:W.,andKnowlton, F. H., Geologyo e e ows one 6 Blackwelder, Ell·ot, A reroonna•'ssan· - ce of the phosphate deposits n 

National Park: u: .. S. Gool. Suryey Mon. 32, pt. 2, 1899. . western Wyomj.ng: U. S. Gaol. Sury~y Bull..4(0, P· 455, 191l. · 
114 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY,. 1918. 

with or closely resembling one that occurs in 

the Thaynes limestone in southeastern Idaho. 

The paleontologic and lithologic evidence at 

hand does not warrant positive statements 

as to the relations of the upper part of the 

Teton to the Idaho or Wyoming sections. 

Exclusion from the Teton of the basal portion, 

equ~valent to the Phosphoria formation, leaves 

the higher shaly brown limestone and red 

beds of Triassic age to which the name 

Teton could be applied, but this seems inadvisable for several reasons, one of which is that 

the name has not been used for areas outside 

of Yellowstone Park. It is therefore believed 

that the use of the name Teton will be discontinued when enough additional field work 

shall have been ·done both in Montana and 

southeastern ~daho to permit the proper appli-

.cation of formation names now in· use in 

Idaho and Wyoming. 

ELLIS FORMATION. 

In late Jurassic time, subsequent to a long 

erosion interval during which there was more 

or less tilting of the strata, a subsidence brought 

in from the northwest an arm of the sea in 

which were deposited the sediments of the 

Ellis formation. The rocks consist of fossiliferous greenish shale and limestone and a 

variable amount of rust-brown weathering 

sandstone and conglomerate. At Elkhorn 

mining camp, near Helena, and for 70 miles 

to the south, the Ellis beds rest on n1ore or less 

disturbed strata of the Phosphoria formation, 

but farther south th~ Ellis and Phosphoria 

are separated by Triassic shaly beds that 

thicken southward and constitute a portion of 

the Teton formation. The Ellis beds are 

about 200 feet thick in Yellowstone Park but 

thicken northward and northwestward to 

about 400 feet in the Livingston and Philipsburg regions. It is suspected that the Ellis 

represents only the basal portion of the several 

thousand feet of the marine Jurassic beds in 

southeastern Idaho but corresponds closely 

with the Sundance formation of Wyoming. 

KOOTENAI FORMATION. 

Overlying the Ellis formation is a motley 

aggregation of beds consisting in great part of 

reel and green shale with conglomeratic sandstone and quartzite, and including near the 

top a limestone member crowded with gastropods. These beds, which are wholly nonmarine, lie between the marine Jurassic and 

marine Upper Cretaceous beds. On j;he basis 

0 

of lithology they are correlated with the 

Kootenai formation of the Philipsburg quadrangle, which is Lower Cretaceous. They 
U. S. GEOLOGICAL SURVEY 

F.E.ET 

zpoo 

1,900 

1,8QO 

1,700 

1,600 

1,500 

1,400 

1,300 

1,200 

1,100 

1,000 

900 

800 

700 

600· 

500 

400 

300 

1 

Near CardweJJ, 

·Mont.· 

2 

Indian Creek 

T.8S.,R.2E. 

-Montana 

principal meridian 

3 

Snowcrest Mountains 

T.IOS.,R.3W. 

Montana 

principal meridian 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

<~ wnosnnate bed 

4 

Idaho-Montana 

State line near Red Rock Lakes 

/ 

PROFESSIONAL PAPER 120 l'LA.TE X 

5 

Quadrant Mountain 

Yellowstone 

National Park 

// 

/// 

/ 

// 

/ 

/ 

//// 

//// 

/" 

/ / 

6 

Dinwooay Uike,'Nyo. 

T.4N.,-R.5W. 

Wind River meridian 

/ / / 

FEET 

2,~ 

2,400 

2,300 

2,ZOO 

2,100 

2,000 

1,400 

1,300 

1,200 

1,100 

1,000 

900 

800 

700 

600 

500 

400 

300 

200 

100 

I. '~ '~· G::Z] \.tii:2] 'o MADISON L.IMESTONE ~AOISON L.IMESTON!i 

STRATIGRAPHIC SECTIONS IN SOUTHWESTERN MONTANA AND YELLOWSTONENATIONAL PARK. 

LEGEND 

Umestone 

~ 

L2lill 

Sandstone 

~ = = Nodular chert 

Ill 

Shale 

• Red beds 
PALEOZOIC AND MESOZOIC FORMATIONS OF MONTANA AND WYOMING. 115 

may possibly include the equivalent of the 

Morrison formation. The thickness of the 

Kootenai ranges from 1,000 to 1,500 feet. 

The most conspicuous beds of the Kootenai 

are the gray gastropod limestone and a bed 

of conglomeratic sandstone in about the 

middle of the formation, the pebbles of which 

are dark chert. Both the beds are reported 

at 1nany places in western Montana, in Yellowstone Park, and in the adjacent country in 

Wy01ning. They form hogbacks pr.ojecting 

above the poorly exposed shaly red beds of 

the Kootenai and the dark shale of the overlying Colorado formation. 

STRATIGRAPHIC DETAILS IN THE MONTANA 

AND YELLOWSTONE PARK AREA. 

. [See Pl. X.) 

JEFFERSON RIVER CANYON NEAR CARDWELL. 

A few miles east of Cardwell, which is on 

Jefferson River near the mouth of Boulder 

River, the broad valley narrows to a sharp 

canyon just wide enough for the tracks of the 

two railroad lines between the river and steep 

cliffs. On the south side of the valley Oocality 

1, Pl. IX) are ·complete exposures of the 

Quadrant and Phosphoria formations, dipping 

steeply northwestward. Several faults introduce. some doubt as to the total thickness, but 

the sequence of the beds is clear. A condensed 

section of the beds measured here follows: 

Section ncar Cardwell, ·Mont. 

Ellis formation: Feet. 

Limestone, sandy, impure, cross - bedded; 

weathers to rust-brown color; lower beds 

contain fossils.... . . . . . . . . . . . . . . . . . . . . . . . . . . 36+ 

Phosphoria formation: 

Quartzite, dark gray, containing a few quartz 

pebbles and bands of chert and a layer of 

travel-rounded chert pebbles at top......... 42 

Chert in thin shaly layers.... . . . . . . . . . . . . . . . . . 6 

Phosphatic beds consisting of phosphate rock, 

limestone, sandstone, shale, and chert, mostly 

in thin beds. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 

Sandstone, dark gray, slightly dolomitic and 

cross - bedded, containing peculiar ropy 

masses and markings. . . . . . . . . . . . . . . . . . . . . . 29 

Quadrant quartzite: 

Quartzite, alternating with dolomitic limestone 

and thin chert layers; poorly preserved fossils 

in lower part.............................. 140 

Limestone, dolomitic and arenaceous, containing 

alternating thin layers of chocolate-brown shale 

and nodular chert; fossils fairly abundant in limestone but poorly preserved...................... 91 

Feet. 

~hale, brick-red................................. 56 

Conglomerate, with matrix of limestone containing 

rounded pebbles of chert, limestone, and sandstone......................................... 4 

Shale, brick-red, alternating with shaly sandstone, 

with conglomerate made up of pebbles of Madison 

limestone resting on uneven surface of Madison 

limestone.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 

INDIAN CREEK, MADISON VALLEY. 

Indian Creek joins Madison River from the 

east a few miles south of Cameron. Its 

branches drain a rugged area containing nur'nerous alpine peaks in the heart of the Madison 

Range. From a densely timbered basin in the 

Mesozoic rocks the upper waters of the stream 

unite and flow westward through a sharp canyon (Pl. XI, A) in pre-Cambrian rocks bordered on the east by Paleozoic rocks that dip 

steeply northeastward. In sees. 20 and 21, T. 

8 S., R. 2 E., on the north canyon wall (loca~­

ity 2, Pl. IX), there are complete exposures of 

strata from the Madison limestone to the top of 

the Kootenai, stratigraphically nearly 2,000 

feet higher. A fault of large displacement cuts 

the lower Paleozoic strata at tlus point but 

does not affect the sequence of the higher 

strata. A con9-ensed section of beds measured 

here is given below. 

Section on Indian Creek, Jfont. 

Kootenai formation: Ft. in. 

Limestone, gray, smooth textured, crowded 

with gastropods in basal portion........... 50 

Shale, ferruginous, with a few sandy layers 

and a layer of ocher-yellow blocky limestones, lavender-colored on fresh fracture. . 400 

Sandstone, quartzitic....................... 38 

Shale, variegated red and brown. . . . . . . . . . . 64 

Sandstone, coarse, with irregular conglomeratic layer in the midst, the pebbles mostly 

dark chert. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 

Shale and clay with carbonaceous layers...... 49 

Sandstone, coarse, arkosic, with undulating 

base .................................... 158 

Shale, yellowish gray, with sandy layers...... 59 

Shale, reddish, with sandy layers ............ 109 

Ellis formation: 

Shale, bluish gray to green, with layers of impme limestone ....................... : . . 98 

Sandstone, green, friable.................... 14 

Limestone, granular, gray, rich in fossils.... . 32 

Shale, greenish, weathering yellow. . . . . . . . . . 18 

Limestone, gray, sparingly fossiliferous ... ·. . . 51 

Limestone, gray, shaly, richly fossiliferous. . . 88 

Shale, calcareous, gray, fossiliferous... . . . . . . 28 

Unconformity(?). 

I 
116 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

Ellis formation-Continued. Ft. in. 

Basal member of Ellis or possiblyequivalent 

of Nugget sandstone of western Wyoming:. 

Shale, ocherous, sandy, gypseous in upper 89 

part................................ 89 

Shale, calcareous, sandy. . . . . . . . . . . . . . . . 12 

Limestone, impure, sandy ...... ~---····· 13 

Sandstone, cross-bedded, yellowish, friable................................. 42 

Unconformity. 

Triassic marine beds: 

Shale, sandy, grading downward into thinbedded limestone that weathers sepiabrown, closely resembling the Dinwoody 

of Wyoming, containing Lingula n. sp. and 

other fosails. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 

Phosphoria formation: 

Sandstone, dark gray, containing irregular 

chert layers and columnar rods of lightercolored sandstone. . . . . . . . . . . . . . . . . . . . . . . 65 

Chert in thin· dark wavy layers..... . . . . . . . . . 33 

Phosphatic beds: 

Phosphate rock, gray, coarsely oolitic ... . 

Limestone, dark gray .................. . 

Shale .. : ..................... · ......... . 

4 

10 

2 

Phosphate rock, black, oolitic, friable, 

with 2 inches of shale near middle; 

59.52 per cent tricalcium phosphate .. 

sp.~le, carbonaceous ................... . 

2 .11 

1 10 

the resistant Quadrant quartzite. (See Pl. 

XI, B.) The most interesting features of the 

stratigraphy of this range are the unusual 

thickness of the Quadrant formation as compared with its thickness in the section in the 

Gravelly Range, 10 miles to the east, and 

the prominent development of the dark, 

richly fossiliferous .limestone in its lower portion. The following fossils were identified by 

' G. H. Girty, who regards them as of early 

Pennsy~vanian age: 

Lingula sp. 

Lingulidiscina sp. 

Schizophoria n. sp. 

Derbya robusta? 

Productus cora. 

Productus aff. P. coloradoensis. 

Productus aff. coloradoensis var. 

Productus n. sp. 

Spirifer rockymontanus. 

Composita subtilita. 

Hustedia mormoni. . The subjoined section shows all but the uppermost beds of the Quadrant as measured in 

sec. 26, T. 10 S., R. 4 W. (loc.ality 3, Pl. IX): 

Section of Quadrant quartzite in Snowcrest Mountm:ns, Mont. 

Phosphate rock, impure, co:utaining fish 

bones .... :· ......................... . 4 Feet. 

Limestone, dolomitic, with gray sandy layers........ 80 

Sandstone, quartzitic, gray, with two thin layers of Sandstone, cherty ........................ . 6 

Quartzite, dark gray ...................... . 

Shale ..................... · ................. . 

12 brownish-mottled shale ..... ·.. . . . . . . . . . . . . . . . . . . . . 207 

. Limestone, sandy, containing phosphatized 

fossil fragments and travel-rounded chert 

pebbles ................................. . 

Quadrant quartzite: . 

·sandstone,·.· .quartzitic, gray, cross-bedded, 

not measured. 

6 

3 Limestone, cherty, dolomitic, with thin sandy layers. 29 

Sandstone, quartzitic, gray, with thin layer of black 

shale in upper part and interbedded layers of dolomitic and smooth-textured dark-gray limestone ..... 247 

Limestone, dark gray, sparing! y fossiliferous; several 

quartzite layers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 

Quartzite, pinkish.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 

Limestone, dark gray, shaly to massive layers, with 

scattered brown to black chert nodules; fossils ex- There is some question as to the 1ower limit 

of the Ellis-formation in the preceding section. 

It seems, clear that the· position of the great 

unconformity is at the base of the yellow sandstone t.h~t. r_ests. on the "Triassic marine beds, 

but the overlying shaly gypsiferous beds apparently represent ·continental sedimentation 

in Jurassic time prior to the encroachment of 

the Ellis Sea and if so would not appropriately 

be included ·in ·the Ellis. Possibly these gypsiferous beds and the yellow sandstone represent the: Nugget sandstone -of we~tern Wyoming, as suggested in the diagram (fig. 14). · 

. SNOWCREST MOUNTAINS. 

The ~ri.owcrest Mountains are west of Ruby 

River, .a.b.out. 20 miles a little west of south 

from Virginia City. The highest peaks, more 

than 10,000 feet in elevation, are capped by 

tremely abundant, especially in shaly limestone 

(see list above) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 

Rocks poorly exposed............................. 50 

Sandstone, conglomeratic at base, possibly basal member o~ Qu~drant for~ation; approximate thickness. 20 

Rocks not exposed.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 

Limestone of fissile shaly structure, rich in fossils. 

This is appare.n.t_ly_ :;~._part of the Madison but repre-

.sents a phase not found elsewhere to the east or 

southeast. · 

IDAHO-MONTANA ·sTATE LINE OPPOSITE RED 

ROCK LAKES. 

.On the State line between Idaho and :h1ontaha, 'iii the Centennial Range south of the Red 

Rock: Lakes (Pl. XII), about 35 miles southeast of the locality in the Snowcrest Mountains 

above described,:· the Quadrant formation 

proper is greatly reduced in thickness, bein_g 

0 
U. S. GEOLOGICAL SURVEY 

A. CANYON OF INDIAN CREEK, MADISON RANGE, MONT. 

Showing cliffs of quartzite of the Phosphoria formation (b) overlain by shaly Mesozoic 

beds (a). 

PROFESSIONAL PAPER 120 PLATE XI 

B. PRINCIPAL PEAK IN SNOWCREST RANGE, MONT. 

Consisting of Madison limestone (lowest exposures in view), overlain by shaly 

limestone of the Quadrant quartzite capped by quartzitic beds which form the 

talus slopes in the foreground. 
U. S . GEOLOGICAL SURVEY PROFESSIONAL PAPER 120 PLATE XII 

A. VIEW WESTWARD ALONG CREST OF CENTENNIAL RANGE FROM POINT NEAR MONTANA PRINCIPAL 

MERIDIAN. 

Bed Rock Lakes in distance. The rocks are Phosphoria formation, Quadrant quartzite, and Madison limestone. 

B . SHALY CALCAREOUS BEDS ALONG CREST OF CENTEN IAL RANGE, EQUIVALE 

OF WYOMING. 
PALEOZOIC AND MESOZOIC FORMATIONS OF MONTANA AND WYOMING. 117 

probably no n1ore than 200 feet thick, as compared with 900 feet in the Snowcrest locality. 

The upper sandy beds and m1derlying fossiliferous limestone are present, however, and a 

fossil collection shows close relation with the 

fauna of the thick shaly limestone in the Snowcrest section. The red shale usually observed 

at the base of the Quadrant is absent, and 

there is only a few feet of ocherous sandy beds 

resting on the n1assive white saccharoidal Madison limestone. 

The Phosphoria formation at this point resembles in lithology the beds exposed on Indian 

Creek but contains in addition a valuable bed 

of phosphate rock at the base, nearly 4 feet 

thick and carrying 70 per cent of tricalcium 

phosphate. This bed, which is evidently of 

clastic origin, consists chiefly of fragments of 

phosphatized shells of the fossil Lingulidiscina. 

At the base there is a few inches of quartz or 

6hert conglomerate 111arking the lower limit of 

the Phosphoria formation. 

QUADRANT MOUNTAIN, YELLOWSTONE PARK. 

Quadrant Mountain, a prominent topographic feature in the northwestern part of 

Yellowstone National Park, presents bold ex-

,posures of the quartzitic beds which have been 

named Quadrant quartzite, as explained on 

pages 111-112. Below is given part of a section 

measm·ed by Weed 1 at the southeast end of 

the n1ountain (locality 5, Pl. IX). The portion 

of the Teton assigned to the Phosphoria under 

the new classification is indicated. 

Section on Qtwdrant Mottntain, Yellowstone National Park. 

[:Measured by W. H. Weed.) 

Teton: Feet. 

Sandstone, red and orange-colored, coarsely 

gra.nular; weathe~·s in blocks. . . . . . . . . . . . . . . . . 15 

C'n.lcareous shale, dark slate-colored, fossiliferous. 5 

Limestone, bright yellow, fissile, with platy 

debris, grading into yellow-and red spotted calcareous sandstones below. . . . . . . . . . . . . . . . . . . . 40 

Shales, light greenish drab, changing to red and 

grading into overlying beds. . . . . . . . . . . . . . . . . . 75 

Conglomerate of red and gray quartz pebbles in 

limestone matrh: ... ,. . . . . . . . . . . . . . . . . . . . . . . . . 10 

Cherty sn.ndstone, the lower part withotit chert, 

is brown; slightly calcareous at base, becoming 

·more so n.bove [Phosphoria formation]. . . . . . . . . 100 

Quadrant: 

Limestone, dense, white, weathering same color.. 10 

Sandstone and limestone in alternating bands.... 15 

Limestone, light gray and dense and pure....... 12 

J U. 8. Geol. Survey Mon. 32, pt. 2, p. 34, 1899. 

Quadrant-Continued. Feet. 

Quartzite, pure white, thin bedded; forms a persistent band along face of mountain. . . . . . . . . . . 6 

Quartzite, more thickly bedded, white.......... 65 

Limestone, very light gray, somewhat dense, containing very small fragments of light-colored 

chert ................................. _...... 10 

Quartzite, white, calcareous, with intercalated 

bands of limestone carrying quartzite fragments 30 

Limestone, light gray, with angular fragments of 

sandstone. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

. Quartzite, white, weathering pink and rust color 

but appearing black when seen from a distance, 

owing to the growth of lichens upon it. . . . . . . . 130 

Limestone, light gray, dense .. ----------------- 2 

Sandstone, well banded, white, saccharoidaL.... 6 

Sandstone, very calcareous, saccharoidal, white 

and rust color. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 

Talus slope of sandstone blocks; also of cherty 

limestone.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 

Additional sections , measured at several 

places on Quadrant Mountain during the present investigation are given below. The Phosphoria exposures were found at the south end 

of The Pocket, a peculiar natural amphitheater 

cut into the plateau surface of the mountain 

top. Complete exposures of the Quadrant 

quartzite were found about 2 miles to the 

southwest, on the north face of Bannock Peak. 

(See Pl. XIII, A.) 

Detailed section of Quadrant and higher formations on Quadrant Mountain. 

Triassic beds: Ft. in. 

Limestone, gray, thin bedded; weathers 

sepia-brown; grades up into shaly, sandy 

yellowish beds overlain by red shale; 

Lingula n. sp. is plentiful in the limestone 60+ 

Phosphoria formation: 

Sandstone, dark gray, with scattered chert 

nodules .... ·_ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 ± 

Chert, in ropy masses and wavy layers, with 

irregular sandy layers in upper part....... 30 

Sandstone, dark gray, with cauda-galli markings on bedding and scattered siliceous 

nodules and ropy masses; :fishbones plentiful. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 

Phosphatic rock, gray, with green specks.... 1 2 

Sandstone, dark gray, with markings; chert 

and fishbones similar to those in 9-foot 

sandstone above.......... . . . . . . . . . . . . . . . . 23 

Quartzite, dark gray. . . . . . . . . . . . . . . . . . . . . . . 16 

Phosphate rock, sandy, resinous; has brown 

appearance on fresh fracture; contains fragments of Lingulidiscina . ............ : . . . . 3 2, 

Quartzite, gray, phosphatic in upper part... 18 

Quadrant quartzite: . · 

Limestone, dolomitic, white, finely crystalline. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 

Sandstone, gray, cross-bedded. . . . . . . . . . . . . . 16 

Limestone, dolomitic, white, finely crystalline. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 
118 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

Quadrant quartzite-Continued. Ft. in. 

Sandstone, quartzitic, alternating with sandy 

dolomitic beds; poorly preserved fossils 

plentiful near base ....................... 350 

Shale, red, sandy, slightly calcareous........ 11 

Sandstone, conglomeratic, yellow and red, 

resting on Madison limestone. . . . . . . . . . . . . 18 

The beds above the Quadrant quartzite 1u 

this section constitute the Teton formation. 

FORMATIONS IN WEST-CENTRAL WYOMING. 

The sequence of late Paleozoic and early 

Mesozoic formations in west-central Wyoming 

is represented in the following table. Their 

probable equivalence with the section to the 

northwest in· Yellowstone Park and Montana 

is indicated in Plate X. 

Late Paleozoic and early .Mesozoic formations in westcentral Wyoming. 

Feet. 

Sundance formation (Jurassic), limestone, green 

shale, and sandstone ........................ 200- 300 

Chugwater formation (Triassic), largely red 

sandy shale, with sandstone and more or less 

gypsum ................................... 800-1,400 

Dinwoody formation (Triassic), shaly brownish 

fossiliferous limestone. . . . . . . . . . . . . . . . . . . . . . 50- 200 

Park City formation (Permian and Pennsylvanian), fossiliferous limestone and shales ... 150- 225 

Tensleep sandstone (Pennsylvanian) .......... 200- 500 

Amsden formation (Pennsylvanian and late 

Mississippian), sandstone, limestone, and 

shale. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200- 300 

It has been shown by the writer 1 that 

although the Chugwater red beds are in large 

part Triassic, the lower portion in the Big 

Horn Mountains and elsewhere in central 

Wyoming is of earlier Triassic, Permian, and 

Pennsylvanian age and was deposited contemporaneously with the marine Triassic 

(Dinwoody) and Permian and Pennsylvanian 

(Park City) beds to the west. 

AMSDEN FORMATION AND TENSLEEP 

SANDSTONE. 

The Amsden formation, which rests on the 

Madison limestone, is somewhat similar in 

litho logy to the lower portion of the. Quadrant 

quartzite of Montana, with which it is correlated, but at no place has ~t been found to 

contain richly fossiliferous beds, such as have 

been discovered in Montana. In the western 

part of the Wind River Mountains the Amsden 

consists of massive white sandstone at the 

1 Condit, D. D., Relations of the Embar and Chugwater formations in 

central Wyoming: U. S. Geol. Survey Prof. Paper 98, pp. 263-270, 1916. 

base, overlain by interbedded gray to yellowish 

shale, sandstone, and thin beds of lin1estone. 

Some of the shale beds are deep red. 

The Tensleep consists almost entirely of 

sandstone, with a few interbedded dolomitic 

layers that locally contain marine fossils. The 

beds correspond so closely in position, thickness, and lithology with the upper portion of 

the Quadrant quartzite that there is no question as to their correlation. It is suggested also 

that the Tensleep may be in part equivalent 

to the Weber quartzite of southeastern Idaho 

and Utah. 

PARK CITY FORMATION. 

Above the Tensleep sandstone in the Wind 

River Mountains is a sequence of prevailingly 

calcareous beds correlated by Blackwelder 2 

with the Park City formation of Utah on the 

basis of paleontologic and lithologic evidence. 

The Park City beds, together with overlying 

calcareous brownish shaly beds of Triassic age, 

constitute the Embar formation of Darton,!J 

who applied this name to strata believed to 

be of ''Permo-Carboniferous" age, lying between the Tensleep sandstone and Chugwater 

red beds at a locality in the Owl Creek Mountains. This grouping into one formation of 

beds of Pennsylvanian, Permian, and Triassic 

age and of widely different lithology is comparable to the grouping of the beds in the 

Teton formation of Y ellowstohe Park, and 

the only reason for retaining Embar as a formation name is its convenience as a term for 

use in areas where the Dinwoody and Park 

City can not be differentiated. 

The portion of the Embar formation equivalent to the Park City beds in the Wind River 

and Owl Creek mountains (see Pl. XIII, B) 

consists largely of limestone with calcareous 

shale and nodular chert. The general sequence is as follows: 

Generalized section of Park City formation in Wind River 

and Owl Creek mountains, Wyo. 

Siliceous greenish limestone grading up into gray resist- . 

ant limestone, with abundant fossils including Derbya, 

Pseudomonotis, Leioclema, and Spiriferina pulchra. 

Nodular greenish phosphatic chert interbedded with 

many shale laminae. 

2 Blackwelder, Eliot, Stratigraphy of the Wind River Mountains, 

Wyo.: U.S. Geol. Survey Bull.- (in preparation). 

a Darton, N. H., Geology of the Bighorn :Mountains: U.S. Geol. Survey Prof. Paper 51, p. 35, 1906. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 120 PLATE Xill 

Showing M adison limestone (Cm) and Quadrant qu a rtzite (Cq) at head of cirque valley. 

d 

C I '---.A.--..,, I I 

I 

B. UPTURNED BEDS ON SOUT H SLOPE OF OWL CREEK MOU TArNS, WYO., NEAH SHOTGUN CREEK, T. 7 N., R. 1 E . 

a, Tcnsleep sandstone, formiug highest hills ; b, Park City formation, with resistant upper limestone member; c, shale of Din woody formation, moslly covered by talus ; d, shaJy red beds of Chugwater formation. 
PALEOZOIC AND MESOZOIC FORMATIONS OF MONTANA AND WYOMING. 119 

Phosphatic shale of sepia-brown color,. with one or more 

. layers of oolitic phosphate rock and phosphatic limestone at the base. 

Limestone with geodes, chert masses, and many fossils, 

among which are Productus nevadensis, Leioclema, Spiri.ferina pulchra, and Productus subhorridus. 

Argillaceous shaly limestone and sandy calcareous shale 

of yellowish color. 

Dolomitic gray fossiliferous limestone, resting with slight 

unconformity on the 'rensleep sandstone. 

Paleontologic data recently presented by 

Branson 1 support the belief of Girty that the 

lower portion of the Park City beds is of PennsylYanian age. Branson's conclusions are the 

result of study of both vertebrate and invertebrate fossils. 

DmWOODY FORMATION. 

1"~he name Dinwoody formation has been 

adopted for the upper shaly portion of the 

Embar on the suggestion of Blackwelder, 

from Dinwoody Canyon, in the Wind River 

Mountains, where the formation, about 200 

feet thick, consists of pale-green to white clay 

and shaly limestone that weather brown and 

contain obscure pelecypod shells. The Park 

City and Dinwoody beds found at this locality are described by Blackwelder in an unpublished bulletin on the stratigraphy of the 

Wind UiYer Mountains. The consensus of 

opinion of seyeral observers is that the Dinwoody beds are to be correlated with the Woodside shale (Lower Triassic) of southeastern 

Idaho. The beds are lithologically identical 

with strata in the middle portion of the series 

of beds in Yellowstone Park designated the 

Teton formation by Weed. 

A complete section of the Embar measured 

by Blackwelder 2 at Dinwoody Canyon 1s 

giyen below. 

Section in Dinwoody Canyon, Wyo. 

Dinwoody formation: 

Pale-green to white clay, with local sandy 

and calcareous beds, overlain conformably 

by bright-red sandy shale of the Chugwater 

Ft. in. 

formation ................................ 130 

Gray shaly limestone, weathering brown..... 28 

Alternate calCareous and sandy shale and 

argillaceous sandstone in thin beds. . . . . . . 12 

Dark argillaceous limestone with shale partings containing many obscure pelecypod 

shells.................................. 10 

1 Brnnson, E. B., The lower Em bar of Wyoming and its fatma: Jour. 

Ooology, vol. 24, pp. 639-664, 1916. 

2 Hlackwoldor, Eliot, A reconnaissance of the phosphate deposits in 

western Wyoming: U.S. Geol. Survey Bull. 470, pp. 476-477, 1911. 

Park City formation: Ft. in. 

Grayish sandy shale, shaly limestone, and 

shaly sandstone, in alternate beds. . . . . . . . 75 

Massive gray crystalline lin1estone with fossil 

Bryozoa and brachiopods ................ . 16 6 

Nodular greenish-gray clay, greenish limestone, and chert; Spirijerina pulchra, il'UStedia meekana, Derbya sp., crinoids, and 

Bryozoa iri abundance ................... . 

Alternating sepia-brown phosphatic and calcareous shale and shaly limestone, with 

thin beds of chert near the top; abundant 

6 

Product1.ts nevadensis? near the base ...... . 35 6 

Brown shale and soft nodular black and gray 

phosphate rock interlaminated (30.5 per 

cent tricalcium phosphate) ............. . 1 8 

Dark greenish-gray oolitic and argillaceous 

phosphate rock (41 per cent phosphate) ... 

Gray to sepia-brown shale, full of oval nodules 

somewhat more calcareous; abundant Spirijer, Producttts, etc. (average 8.5 per cent 

1 

phosphate) ............................. . 12 5 

Hard greenish-bro,vn phosphatic limestone, 

with glauconite grains (23. 7 per cent phosphate) ................................. . 

Brown argillaceous limestone and calcareous 

shale, nodular, as above; abundant Productus nevadensis, "P. cora,. P. Sttbhorridtts, 

Spinferina pttlchra, P'ttgnai ~ttah, Bryozoa, ' 

. etc. (8 per cent phosphate) ............. . 6 

Dark-drab or brown fetid limestone in massive beds; upper layers crowded with 

Bryozoa................................ 21 

Green clay shale v;rith thin beds of chert • 

and platy gray limestone................. 43 

Gray speckled phosphatic sandstone......... 1 

Earthy white sandstone .................... . 2 

Greenish-gray speckled phosphatic sandstone containing Lingulidisfj,na utahensis, etc. (27 .4 per cent tricalcium phos7 

phate) ................................. . 

Light-gray earthy limestone ............... . 

Dark-green shale .......................... . 

2 2~ 

1 9! 

1 3~ 

Pale-gray smoky dolomite with seams of 

black chert and pores full of black bitumen .......... :........................... 25 

White calcareous sandstone and conglomerate of chert pebbles; lies with obscure 

unconformity upon the Tensleep sandstone..................................... 1 7 

CHUGWATER FORMATION. 

The Chugwater red beds, 800 to 1,450 feet 

thick in west-central Wyoming, present prohlems in sedimentation that have engaged the 

attention of a number of workers who are not 

in agreement as to the origin of these beds. 

Among their striking features are the uniformity in thickness and texture of individual 

members .over wide are~; the prevalence of 

ripple marks on horizontal beds through much 
120 SHORTER. CONTRIBUT'IONS TO GENERAL GEOLOGY, 1918. 

of the formation; the absence of sun cracks 

and fossils of land animals except in the upper 

portion; and the extensive occurrence of gypsum 

beds near the top. It is not the purpose of 

this paper to consider in detail the peculiarities of the Chugwater or the different hypotheses concerning its origin. It is evident, however that mature conclusions can be reached ' only after a detailed study of the red beds 

throughout Wyoming and adjacent areas. 

The question of age alone illustrates this point. 

In western Wyoming the lowest red beds 

overlie marine fossil-bearing brown shales of 

Triassic age that are regarded by several 

observers as equivalent to the Lower Triassic 

Woodside shale of Idaho. Furthermore, it is 

suspected that the lower Chugwater beds of 

western Wyoming grade laterally into the 

marine Thaynes _limestone of Idaho, which are 

of Lower Triassic ·age, or at least that they 

represent partial-time equivalents of these 

beds. 

A fossil collection made brDarton 1 in the Big 

Horn ·River canyon near Thermopolis, Wyo., 

is of interest in this connection. The fossils 

obtained in a limesto:Ue 150 feet below the top 

of the formation were found by G. H. Girty 

to include Natica lelia, Bakewellia, Pleurophorus, and Aviculipecten, undoubted marine 

types, constituting a fauna which is referred 

with considerable confidence to the Triassic. 

This occurrence is of additional interest as 

indicating the marine origin of a portion of 

the Chugwater, as contended by Branson.2 

In the Big Horn Mountains, in the central 

part of the State, the ·lowest red beds of the 

Chugwater have been shown by the writer 3 

to be of late Pennsylvanian age. 

The age of the uppermost beds of the Chugwater formation is uncertain. Wherever present in Wyoming they are overlain by the Sundance formation, which is Upper Jurassic, but 

it is "a question whether the deposition of the 

gypseous shale, cross-bedded sandstone, and 

nonmarine limestone characteristic of the upper 

part of the Chugwater may not have been 

1 Darton, N. H., Geology of the Bighorn Mountains: U. S. Geol. 

Survey Prof. Paper 51, p. 40, 1906. . 

2 Branson, E. B., Origin of the Red Beds of western Wyoming: Geol. 

Soc. America Bull., vol. 26, pp. 217-230, 1915. 

s Condit, D. D., Relations of the Em bar and Chugwater formations 

in central Wyoming: U. S. Geol. Survey Prof. Paper 98, pp. ·263-270, 

1916. 

largely contemporaneous with the early Jurassic base-leveling so plainly recorded. in the 

truncated beds to the north, in Montana. 

SUNDANCE FORMATION. 

The Sundance formation of Wyoming is regarded as the equivalent of the Ellis in 1fontana, with which it agrees fairly well in lithology, thickness, and fossil content. The Sundane~ consists largely of greenish calcareous to 

sandy shale, with a resistant dark-gray limestone near the middle. Both the shale and the 

limestone are richly fossiliferous, and the most 

characteristic species are Belemnites densus, 

Gryphaea calceola, and stem segments of the 

crinoid P entacrinus asteriscus. 

RECORD OF JURASSIC BASE-LEVELING. 

The most striking evidence of prolonged 

erosion in Jurassic tin1e is furnished by the 

contact of the late Jurassic marine beds (Ellis) 

with successively older. formations as followed 

, northward across :Montana. This feature is 

graphically shown in figure 14. The substrata 

along the Idaho-Montana State line near Y el-· 

lowstone Park are limestone or red beds of 

Triassic age, and successively lower forn1ations. 

appear northward to Elkhorn mining camp, 

about 20 miles south of Helena, where the sub-· 

strata are beds probably 75 feet below the top 

of the Phosphoria formation. Fishe~ 4 has 

stated that in places in the Great Falls region, 

in northern Montana, the Ellis rests on the, 

Madison limestone. 

Study of the erosion surface from place to· 

place reveals the presence of peculiar yellowish. 

earthy sandstone, ferruginous gypseQus shale, 

and local limestone beds, all making up a mot-· 

ley aggregate related neither to the overlyingEllis nor to tlie underlying formations. These. 

heterogeneous materials constitute the sedimentary record of events that preceded or ac-· 

companied the advance of the sea from the. 

northwest in late Jurassic time. Their thick-· 

ness, ranging from a few feet to little more than. 

100 feet, is direct evidence of the slight relief of 

the land surface, the inequalities of which were. 

leveled to form the floor upon which the marine. 

Ellis beds ·were deposited. 

4 Fisher, C. A., Geology of the Great Falls coal field, M.ont.: U.SGeol. Survey Bull. 356, p. 27, 1909. 
PALEOZOIC AND MESOZOIC FORMAT'IONS OF MONTANA AND WYOMING. 121 

The thickness of strata r~1noved by Jurassic 

erosion in northern :Montana n1ay have been 

2,000 feet, if the Chugwater red beds once extended over that area. The extent to which 

the Chugwater was eroded in Wyon1ing is not 

evident, but it seems probable that in the westcentral part of the State, where the beds are 

1,400 feet thick, they remain ahnost intact, 

and that the upper portion, including the gypseous beds, may be in part a product of Jurassic 

sedin1entation. 

The disposition of the great n1ass of material 

.stripped fron1 the northern area is a matter of 

speculation, but in the writer's op1n1on this 

erosion n1ay have furnished the sediments of 

the shale and sandstone series of southeastern 

Idaho lying between the n1arine Lower Triassic 

(Thaynes limestone) and marine Upper Jurassic (Twin Creek limestone). It is probable 

that in the 1neanwhile the Wyoming area, a 

low, nearly level plain, which was intermittently 

occupied by small bodies of water and in which 

neither erosion nor deposition ofo considerable 

magnitude occurred, furnished the conditions 

necessary for the formation of extensive but 

variable gypsum and li1nestone beds . 
' 
NEW GHAPHIC METI-IOD FOR DETERMINING THE DEPTH AND THICKNESS OF STRATA AND THE PHOJECTION OF DIP. 

By HAROLD S. PALMER. 

INTRODUCTION. 

Geologists, both in the field and in the office, 

frequently encounter trigonometric problems 

the solution of which, though sitnple enough, 

is somewhat laborious by the use c!>f trigonometric and logarithmic tables. Charts, tables, 

and diagrams of various types for facilitating 

the computations have been published, and 

a new method may seem to be a superfluous 

addition to the literature. IIowever, it is felt 

that the simplicity and accuracy of diagrams 

H 

a 

I 

I 

I 

I 

I 

:n 

I 

I 

'\ 

(NOTE.·--Diagram I may be used not only 

for the problem above stated but also to 

obtain the difference in elevation between two 

points by omitting E and letting D equal the 

difference in elevation, H the horizontal clist~nce, and A the vertical angle.) 

II. To find the thickness of a stratum,' given 

the dip of the stratum, the horizontal distance 

across its outcrop at right angles to the strike, 

and the differenee in elevation of the upper 

and lower boundaries of the stratum. There 

FIGURE :15.-Diagram showing three cases in computing depth. 

. . 

such as are presented in this paper warrant the 

addition. The alinement diagram. is used to a 

very considerable extent by' engineerfit especially mechanical engineers. The principle of 

the alinement diagram is explained herein, 

but rigorous demonstration is not attempted. 

Alinement diagrams are given for the following problems, which are numbered to agree 

with the numbering of the diagrams. The 

charts published herewith are suitable for use. 

I. To find the depth to a stratum, given the 

dip of the stratum, the horizontal distance 

from the outcrop, and the difference in elevation between the outcrop and the point at 

which the depth is desired. (See fig. 15.) 

The for.mula is 

D = H tan A ± E ___________ (1 

in which D = depth to stratum, I-I= horizontal 

distance frorn the outcrop, A= dip, E = difference in elevation. 

are three cases, ~pending oo the relation of the 

dip of the beds to the slope of the ground. 

(See fig. 16, a, b, and c.) 

Case 1, where the ground is level. By inspection of figure 16, a, it is seen that the 

formula is 

T = H sin A ____________ (2) 

in which T = thickness, H = horizontal distance 

from outcrop, and A= dip. 

Case 2, where the ground slopes opposite to 

the dip. In figure 16, b, 

but 

Now 

or, as 

T=m-'-l 

m=H sin A 

. l=E cos A 

cos X=sin (90°-X) 

l=E sin (90°-A) 

123 

• 

' 
0 

124 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

Therefore 

T=H sin A+E sin (90° ;_A) _____ (3) 

in which T, H, and A have the same values as 

before, and E is the difference in elevation. 

Case 3, where the ground slopes with the 

dip. In figure 16,c, T=m-l_;making the same 

substitutions as in case 2, we find 

T=H sin A-E sin (90°-A) _____ (4) 

in which T, H, A, and E have the same values 

as before. 

~· / T 

I 

a 

plane of a supposed structure section, is desired. a· is the desired projection of A. B is 

the angle between the plane of the section and 

the strike of the beds, and angle PFS is a 

right angle. The plane PFS is horizontal 

and the lines PQ, FG, and SR are normal to it 

and of equal length, so that the triangle QGR 

is also horizontal and is equal to PFS. 

Now, 

FS=PS sin B 

FS=FG cot A 

PS=PQ cot 0 

Therefore 

FG cot A=PQ cot 0 sin B 

but 

FG=PQ 

so 

cot A=cot 0 sin B 

and, as the tangent is the reciprocal of the cotangent, 

1 1 . B 

tan A= tan C sin 

tan C = tan A sin B ___ ( 5) 

FIGURE 16.-Diagram showing three cases in computing thickness. 

in which 0 = dip of the projected 

angle, A = dip of the bed, B =:= 

angle between strike and plane 

of section. 

The above formula is strictly tnie only where 

the dip of the beds is greater than the slope of 

the ground. (See fig. 16, d.) Where the 

dip is less than the slope the formula becomes 

T=E sin (90° -A) -H sin A _____ (4a) 

The difference is algebraic and not arithmetic, 

so that the formula is practically workable for 

either subcase. 

III. Projection of dips-that is, to find the 

slope of the trace of an inclined plane upon a 

vertical plane oblique to the strike. Consider 

figure 17, a, which is a plan or'map; at A is an 

inclined plane the strike and dip of which are 

shown in the conventional way, and along 

~-Pis a vertical plane upon which this dip is to 

be projected. B is the angle between the 

strike and the section plane. In figure 17, b, 

A is a dip whose projection on SPQR, the 

<!) 

USE OF THE ALINEMENT DIAGRAMS. 

The alinement diagram is worked in an 

extremely simple way. The points on the 

outer scales representing the given quantities 

are joined by a line, and the unknown q uantity, or result, is read at the intersection with 

the middle scale. Interpolation between the 

values marked on the scales is effected just as 

on a slide rule. It is suggested that the edge 

of a draftsman's transparent triangle or a piece 

of slender black thread be used for projecting 

the cross line. 

USE OF THE DEPTH DIAGRAM. 

In using the depth diagram (Pl. XIV and 

problem l), find.the_point on the left-hand scale 

that represents the distance from the outcrop 

to the point at which the depth is desired, and 

join it to the point on t:!J.e right-hand scale that 
U. B. Gl<~OLOGICAL SURVEY 

900 

800 

700 

600 ..... ..... ..... ..... 

..... ..... ..... ..... ..... 

500 ..... 

' ...... 

.400 

300 

200 

..... ...... ..... ..... 

.......................... 

PROFESSIONAl, PAPER 120 l'LATE XIY 

Depth 

to bed 

10,000-

7,000 

3,000 

100 

70 

50 

40 

30 

20 

10 

I 

I j 

..... 

................ 

......................................... 

Dip 

.89° 

ALINEMENT DIAGllAM I, FOR COMPUTING DEPTH. 
DETER.MINING DEPTH AND THJ:OKNESS OF STRATA AND PROJECTION OF DIP. 125 

represents the dip of the beds. At the intersection of the line determined by these points 

with the nuddle scale the depth may be read. 

The dotted line on Plate XIV shows the solution when the distance is 600 feet and the dip 

20°. The depth to the stratum is found to be 

220 feet. 

1'he above rule holds only if the surface is 

level. If the point at whlch the depth is to be 

deternuned is higher than the outcrop~ the 

difference in their elevation is added to the 

depth as read by the above-described method. 

If the outcrop is the higher of the two points, 

the difference of elevation is subtracted from the reading. 

The diagram may be used for 

the converse problem, namely, to 

find the dip of the bed when the 

depth and distance from the outcrop are given. In this case the 

given quantities are set on the 

middle and left scale, and the line 

joining them is produced till it 

cuts the right scale, at which the 

dip is read. Another converse 

proble1n arises when the distance 

from the outcrop is unknown but 

the dip and depth to the stratun1 

the point on the left ~cale that represents the 

difference in elevation of the higher and lower 

boundaries of the outcrop, and at the intersection of the connecting line ,,r_i th the middle 

scale read the correction. The correction is 

added or subtracted as directed above. 

In Plate XV the broken line shows the fuet 

step in solving the problem when the horizontal width of the outcrop is 600 feet and the 

dip is 20°. The thickness is read on the middle 

scale as 206 feet. The dashed line shows the 

correction to be introduced if the differenc~ in 

elevation between the two edges of the out-

/ 

/ 

/ 

/ 

/ 

/ 

/ 

/ 

~~-------­ Q 

s 

b 

G 

are known. In this case known . 

points on the right and middle FIGURE 17.-Diagram for derivation of formula for projected dip. 

scale are joined by a line the extension of 

which give:s the result at its intersection \\rith 

the left scale. 

USE OF THE THICKNESS DIAGRAM. 

In using the thickness diagram (Pl. XV and 

probletn II), find the point on the left scale 

that represents the width of the outcrop and 

join it to the point on the right scale that 

represents the dip of the beds. At the intersection of the line determined by these points 

with the middle scale the tluckness may be 

read. 

'I'he above rule holds only if the surface is 

level. A correction must be added if the 

ground surface slopes in the opposite direction 

to the dip, and the same correction must be 

subtracted if the surface slope and the dip are 

in the same direction. This is the correction 

E sin (90° -A) in formulas (3) and (4). Subtract the dip from 90° and ·find the corresponding point on the right scale. Join it to 

28288°-19-9 

crop. is 50 feet. As there is no 50-foot graduation on the left scale, the decimal point is 

shifted to the right and the 500-foot graduation is joined by a line to the 70 ° mark on the 

left scale (90°-20°=70°). The reading is 470 

feet, but .the decin1al point must be shifted 

back, so the true correction is 47 feet. Then 

if the bed dips "into the hill" the thickness is 

206+47=253 feet; if it dips "with the hill" 

the tluckness is 206-4 7 = 159 feet. 

Like the depth diagram, the thlckness diagram has converse uses, but they can be applied 

only when the ground surface is level. Thus 

if the width of the outcrop ~nd thickness of the 

bed are known the dip can be computed, or if 

the dip and thiclmess are known the width of 

outcrop can be computed. 

USE OF THE PROJECTION DIAGRAM. 

In using the projection diagram (Pl. XVI 

and problem III) fi.J).d the point on the left 

scale that represents the dip and the point on 
126 SHOR,TER. CONTRIBUTIONS TO GENERAL GEOLOGY,- 1918. · 

the right scale that represents the angle between the strike and the plane-upon which the 

dip is to be projected. Join these points· by a 

line~ and at its intersection with the middle 

scale read the projected dip. As this problem 

involves only one case there are no corrections 

to be added or subtracted. 

In Plate XVI the broken line shows the solution of the problem of projecting a dip of 43° 

upon a plane at an angle of 35° to the strike. 

The result, 28°, is read on the middle scale. 

As with the other· diagrams, the converse 

problems may be solved. · Thus, if the trace of 

a bed along a vertical plane and the angle between the strike and the vertical plane are set 

on the middle and right scales, respectively, 

10 

------

5 

0 

good for only one formula, whereas the slide 

rule is applicable 'to many; formulas .. 

Consider figure 18, a, in which ab, cd, and ef 

are parallel lines cut by two secants, ace and 

bdf 'Frome· andf drop two ·lines, eg and lif, 

perpendicular· to- ·ao. By ,inspection of the 

diagram it is seen that 

cd = Y2 ( ab + ef) 

This 'equation is equivalent to saying that 

the space cut off on the middle line is equal to 

half the sum of the spaces cut on the outer 

lines. 

Now, if, as in figure 18, b, the outer lines are 

graduated evenly with equal divisions and the 

middle line is graduated with divisions half as 

20 10 10 100 10 

50 

15 ---- -- 5 ---- ---

10 5 10 

5 

o· .1 ,1 

b c 

FIGURE 18.-Diagram showing three stages in derivation of principle of the alinep1ent diagram. 

the dip of the plane may be read on the left 

scale. Again, if the dip of a bed and the slope 

of its trace on a ·vertical plane are known, and 

these points are set on the left and middle 

scales, respectively, the angle between the 

strike and the vertical plane niay be· read on 

the right scale .. 

PRINCIPLE OF THE ALINEMENT DIAGRAM. 

The alinement diagram is a device by means 

of which certain arithmetic prqcesses (addition, subtraction, multiplication, division, involution, . and evolution) may be mechanically 

or graphically performed. It is similar in principle to the slide rule in that by means of it 

distances. proportional to numbers or to logarithms, are mechanically added, subtracted, 

·~ultiplied, or divided, but this work is done by 

a different mechanical ·process. It· differs further from the slide rule in· that each diagram is 

great, addition can be graphically performed. 

The bases of the three scales are put on the 

same level for convenience only.· The secant 

line is taken so as to cut off SL"{ divisions on 

the left scale and eight on the right scale. It 

must, perforce,. cut 14 divisions on the middle 

scale, and the addition of 6 and 8 is graphically 

accomplished. 

It will be remembered that logarithms are 

essentially exponents (to the base 10 in the 

common system), and that multiplication is 

accomplished by adding the logarithms. This 

is by the algebraic law 

. xmxn = xCm+n) ______ '" __ .;. ___ ( 6) 

which may be verbally stated as follows: The 

multiplic.ation of powers of the same quantity 

is effected by using the sum of the exponents 

a8 the exponen.t for the product. · 

Now ;·jf the m·arkings of the scales are not 

.equidistant :as in figure 18,.b, b1_1t are laid off as 
U. S. GEOLOGICAL SURVEY 

Width of outcrop 

1,000 

900 

800 

PROFESSIONAL PAPER 120 PLATE XV 

Thickness 

1,000 

900 

800 

700 

600 

500 

300 

600 ________ _:_·--~~:::: _________ . ____ 200- 0 

-- ------------- 20 

400 

300 

200. 

100 

100 

90 

80 

70 

60 

50 

40 

30 

10 

9 

8 

.7 

6' 

5 

4 

3 

l 

ALlNEMENT DlAGll.AM 11, FOH. COMPUTING THICKNESS. 

100 

so 

40 

- 30 

- 20 

- 10 
DE'X.ERMINING DEPTH AND ·THICKNESS OF STRATA AND PROJECTION 'OF DIP. 127 

in figure 18, c, so that the distances from the 

base are proportional to the logarithms of 

muubers, we can in effect add logarithms. 

But this is equivalent to multiplying the 

nun1bers. In the figure the multiplication of 

4 and 5 is shown, the result being 20. In 

figure 18, c, the distance on the outer scales 

proportional to a logarithmic difference equal 

to 1 is 2 inches; on the nuddle scale it is half 

as great, or 1 inch. 

'rhe scales n1ay be graduated in proportion 

to logaritluus of trigonometric or othe~ functions as well as in proportion to logarithms of 

nmnbers. It is therefore possible to manipulate a variety of factors. 

Son1etimes it is desirable to compress a scale, 

as for example a log. sin. scale in which the divisions between 1° and 20° come relatively far 

apart. In the charts here presented (Pis. XIVXVI) the scales for logarithms of numbers were 

drawn with a modulus 1 of 10 inches. A log. 

sin. scale with a modulus of 10 inches would 

ha,Te to be 17.5 inches long in order to range 

from 1° to 90°. A log. tan. scale would have 

to be 35.2 inches long to range from 1° to 89°. 

vVhen the moduli of the outer scales are not 

equnl, the 1110dulus of the middle scale is deterJnined by the following formula, in which M3 = 

rnodulus of middle scale, :M1 =modulus of right 

Reale, and M2 =modulus of ·left scale: 

=1\~~~ ------------- (7) 1 . 2 

At the same time, the middle scale must be 

shifted toward that outer scale which has the 

smaller modulus. The position of the middle 

scale is determined by the following equation, 

in which M1 and M2 have the same values as 

before, D1 =distance from middle scale to right 

scale, and D2 =distance from middle scale to 

left scale. 

modulus that any two lines which intersect on 

one of the outer scales and cut off a distance 

on the middle scale equal to its modulus wiJl 

also cut off a distance on the third scale equal 

to its modulus. 

·Let :M11 M2 , and :M3 be the moduli and D1 and 

D2 the distances of the outer scales from the 

rniddle scales. Assume the lettering as indicated. 

B 

AI Gl ,F r-----.n2---- -~-·-- -n,-- --"'1 

.FIGU~E 19.-Diagram for derivation of the interrelation of M1, M2, M8, 

D1, and D2. 

Then in the triangles ACG and AEF 

M:3 1\11 

D~ =D1 +D2 

and 

M3CD1 +D2) =M:tD2 

Sitnilarly in the triangles FCG and FBA 

and 

Therefore 

and 

M3 M2 

Dt Dt +D2 

M3CJ?1 +D2) =M2D1 

M2Dt =MtD2 

D1 :\11 

D2=M2 (q. e. d.) 

Taking this proportion by composition and 

transposing, we have · 

~1·=:1- ------------ --.CS). M:1 D1 2 2 

Tlw principles underlying this and the last 

equation may be deduced from figur~ 19. The 

principles of the diagram require that the middie scale must be so placed and have such a 

1 ~L'ho term "modulus" is used to moan the length on a scale proportional to a mlit dificrc.nco of logarithms. For cxamplo, the outer scales 

in figure 18 nro said to have a modulus of 2 inches because the distance 

from tho point representing 1 to tho point representing 10 is 2 inches. 

1'ho log1\rithm of 1 is 0.000 and tho logarithm of 10 is 1.000, and tho differonce hotwoon those logarithms is unity. 

M1 +M2 D1 +D2 

Now, in the triangles FCG and FBA 

M3 D1 

M2 Dt +D2 

Substituting from the previous equation, we 

have 
128 SHOR.TER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

and solving for M3, we have 

(q. e. d.) 

The length of any scale may be determined 

by the following equation: 

L=M (logF1 -logF2

) ________ (9) 

in which L =the length of the scale, M =its 

modulus, and F1 and F2 =the maximum and 

minimum values of the variable to be represented on the scale. 

This may be explained by an example. 

Suppose it is desired to fit a log. tan. scale 

into a space about 12 inches long. Let F2 = 

tan 1°, and F 1 = tan 8 9°. Then 

log F2 =log tan 1°=8.2419 

log F1 =log tan 89° = 11.7581 

then 

log F 1 -log F2 = 11.7581-8.2419 =3.5162 

and 

or 

L=M 3.5162 

L 

M=3.5162 

Substitute 12 for L: 

:M=12+3.5162=3.41 + 

As an engineer's scale is used in drafting the 

scales and can be conveniently used only for 

:.noduli of 1, 1%, 2, 2.5, 3}i, or 5 inches or 

these' lengths multinlied by 10, we choose a 

modulus of 3 }i inches, which is nearest to 

the inconvenient irrational decimal 3.41 +. 

Substitute 3}i for M and we find L=3}i X 

3.5162 = 11.72 inches. 

ACCURACY AND ADVANTAGES. 

The point may be raised that the calculations made by these charts are not accurate, 

.and in the strictest sense this is undoubtedly 

true. But there are two facts that should be 

borne in mind: (1) Measurements made by 

pacing or by a hand compass or clinometer are 

not accurate; (2) the surfaces with which the 

geologist deals are not true planes. Measurements of angles are seldom accurate within 1°, 

which is approximately equivalent to a.ri arror 

of 1 per cent, and pacing under the most favorable conditions can not be trusted closer 

than to 1 per cent. The undulations of fault 

or bedding planes will usually introduce an 

error of the same or greater magnitude. Therefore it is unsound logic to demand that the 

error in the calculations based upon such 

measui-ements be less than 1 per cent. If the 

chart is used with reasonable care, the error 

is somewhat less than 1 per cent and is therefore negligible. Moreover, the use of the chart 

gives less opportunity for the introduction of 

gross errors, such as come from a mistake in 

multiplication or in the addition of logarithn1s. 

The charts, therefore, have the following 

. advantages over the other methods for solving 

these equations: 

1. They are more speedy. As a test of the 

speed of this method the writer used the first 

draft of the three charts for a series of test 

problems. The time required to solve the 

problems by means of the charts and by 

logarithms 'in the ordinary way was taken 

with a stop watch. It was found that the 

time with the charts ranged from one-sixth to 

one-fourth of that required by the logarithmic 

method. The test was fair to the logarithms, 

as the writer is reasonably proficient in their 

use. 

2. The chances of gross errors are eliminated. 

In the test mentioned in the preceding paragraph the correctness of the answers was 

checked, and a mean error of about 0.2 per 

cent was found, with a maximum of 0.7 per 

cent. One gross error of about 40 per cent 

was made in one of the logarithmic solutions 

and was first dete'cted by the check given by 

the chart solution. 

3. It is unnecessary to keep the formula in 

inind, as it is incorporated in the construction 

of the chart. 
U. S. GEOLOGICAL SURVEY 

Dip 

Projected 

dip 

PROFESSIONAL l'APEH 120 PLATE XVI 

An$le'!f 

proJeCtion 

l,. 

ALINEMENT DIAGRAM III, FOR COMPUTING PROJECTED DIP. 
A CONTRIBUTION TO THE GEOLOGY OF NORTHEASTERN TEXAS AND 

SOUTHERN OKLAHOMA. 

' By LLOYD WILLIAM STEPHENSON. 

PURPOSE AND SCOPE OF THE PAPER. 

The region in central and northeastern Texas 

and southern Oklahoma known as the Black 

and Grand prairies abounds i~ features of interest to physiographers, geologists, and paleontologists, and the pioneer investiO'ators of 

this region must have experienced b renewed 

satisfaction in each day's exploration. The 

reports of Joseph A. Taff, Robert T. Hill, and 

others, published chiefly under the auspices of 

State and Federal surveys, represent with approximate accuracy at most places the general 

distribution of the outcrops of the formations 

in this region, and contain detailed descriptions of many sections that constitute a 

mine of useful information. The reader of the 

present paper is urged, therefore, to hold as 

most important 'the general excellence of the 

earlier reports of these authors and to relegate 

the inaccuracies and mistakes to which his 

attention will be called to the relatively unimportant place in which they belong, remembering at the same time 'that a futur~ generation 

of investigators may find our own shortcomings 

11s great as those we now criticize. 

rrhe present report treats of the area shown 

in Plate XVII, which includes Grayson, Fannin, Lamar, Delta, I-Iunt, and Collin counties 

'I' ex., an d the southern parts of Marshall and ' 

Bryan counties, Okla. It is based on the results of studies carried on during several brief 

field seasons between the years 1911 and 1917 

inclusive. The results are by no means final: 

but enough facts have been obtained to justify IHill,R.T.,GeographyandgeologyoftheBlackandGrandprairies 

their presentation to those WhO may be inter- Tex.,withdetaileddescriptionsoftheCretaceousformationsandspecial 

ested in ~he geology of the region. The pur- reference to artesian waters: u.s. Geol. Survey Twenty-first Ann. Rapt., pt. 7, pl. 66, 1901. . 

pose of the paper is therefore to set .forth the 2 Veatch, A. C., Geology and underground water resources of northern 

present state of knowledge in the areal map- OLouisiana and southern Arkansas: u.s. Geol. Survey Prof. Paper 46, 

p. 68, 1906. 

ping, in the interpretation of structure, and in aTaff,J.A.,TexasGeol.SurveyFourthAnn.Rept.,pp.297-298,1893. 

COrrelation, and to indicate certain mappable 4 Taff, J. A., Chalk of southwestern Arkansas, with notes on its adapt- ability to the manufacture of hydraulic cements: U. S. Gaol. Survey 

units and structural features that have not Twenty-second Ann. Rept., pt. 3, pp. 698-700, 1902. 

heretofore been recognized. 6 Gordon, C. H., Geology and underground waters of northeastern 

Texas: U.S. Gaol. Survey Water-Supply Paper 276, pp. 21-25, pl. 1, 1911. 

. 129 
\ 

130 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

and including the Blossom sand, but he erred in 

correlating the Blossom sand with the Eagle Ford 

clay, and although he noted the geographic 

connection of the Annona chalk with the 

Austin he also failed to recogni~e the upward 

transgression of the chalk in its north~astward 

extension. 

Enos anticline. The general results obtained 

by these three men are embodied in the structure contours shown as an overprint in red on 

the geologic map (Pl. XVII). A more detailed report of their results, with particular 

·r~f~rence to the occurrence of oil and gas, will 

be published later as an economic bulletin. 

ACKNOWLEDGMENTS. Indebtedness is gratefully acknowledged to 

Mr. J. T. Bryant, of Pottsboro, Tex., for inforIn 1911 the writer was accompanied by T. W. mation and per~onal assistance that enabled 

Stanton in a brief examination of parts of the writer and his associates quickly and adnortheastern Texas, including the area in the vantageously to find and study numerous 

longitude of Paris between the North Fork important exposures in northern Grayson 

of Sulphur River and Red River, the vicinity· County, Tex., and southern Marshall County, 

of Cooper, Delta County, and the vicinity of Okla. Mr. Bryant also kindly contributed the 

Sherman, Grayson County. Subsequently he logs of several wells on the Preston anticline. 

frequently conferred with Mr. Stanton in re- Courtesies were also extended to the writer 

gard to the interpretation of the physical and and to his associates by Messrs. R. H. Cook, of 

paleontologic facts ·and has greatly benefited Denison;·M. L. Wilson, of Wolfe City; and J. 

by his many helpful suggestions. Balch Moor, of Bonham, who furnished well 

0. B. I-Iopkins, during a brief visit in 1915, logs and placed facilities for field study at 

determined the stratigraphic succession and their disposal. 

attitude· of the Upper Cretaceous rocks ·that 

appear at the surface in the vicinity of Wolfe. 

City, Hunt County, and Gober, Fannin 

County, Tex. He stated his conclusions to 

the writer and indicated certain favorable 

LITERATURE. 

The principal publications relating to the 

area treated in the present paper are listed below in chronologie order: 

localities for examining outcrops. The area 

was subsequently visited by the writer, who Shumard, B. F., Notes upon the Cretaceous strata of 

traced the several litholog-ic divisions both to Texas: St. :Louis Acad. Sci. Trans., vol. 1, pp. 582-6~0, '-' 1860. 

the northeast and southwest of Wolfe City, as Taff, J. A., and Leverett, S., Report on the Cretaceous 

shown on Plate XVII.· Mr. Hopkins also ob- area north of the Colorado River:· Texas Geol. Survey 

tained by correspondence the logs of several Fourth Ann. Rept., pp. 239-35'4, · 2 maps, 1 plate, 1893. 

wells in northeastern Texas and southern Hill, R.T., On theoccurrenceofartesianandotherunderground waters in Texas, eastern New Mexico, and India~ · Oklahoma, which he generously placed at the Territory west of the 97th meridian: 52d Cong., 1st· sess., 

writer's disposal. s. Ex. Doc. 41, pt. 3, pp. 41-166, 19 pls., 1893. · 

In December, 1917, 0. B. Hopkins and Sid- Hill, R. T., Geology of parts of Texas, Indian Territory, 

ney Powers accompanied the writer in a sup- and Arkansas adjacent to Red River: Geol. Soc. America 

plementary field study of the areas in Grayson, Bull., vol. 5, pp. 297-338, pls. 12, 13, 1894. 

Hill, R. T., and Vaughan, T. W., The Lower Cretaceous 

Fannin, and Hunt counties where the Cre- Gryphaeas of the Texas region: u. s. Geol. Survey Bull. 

taceous formations are involved in the Preston 1 5 1, 1 39 pp., 35 p 1 1898 s., . 

anticline and in the Leonard-Celeste mono- Hill, R. T., PhysicalgeographyoftheTexasregion: U.S. 

clinal nose. The outcrops of key rocks were Geol. Survey Top. Atlas, folio 3, 12 pp., 11 pls., 1900. 

traced, and altitudes were determined at nu- :am, R. T., Geography and geology of the Black and 

Grand prairies, Tex.: U. S. Geol. Survey Twenty-first merous points on them by means of aneroid Ann. Rept., pt. 7, 666 pp., 71 pls., 1901. 

readings. Messrs. Hopkins and Powers con- Taff, J. A., Chalk of southwestern Arkansas: U.S. Geol. 

tinued the determination of altitudes during OSurvey Twenty-second Ann. Rept., pt. 3, pp. 687-742, 

the later part of December and the first half of pls. 47-53, 1902. . 

January, 1918. H. M. Robinson had in 1917 Taff, J. A., U. S. Geol. Survey Geol..Atlas, Atoka f~ho 

d ·. f · 'I I · d d · (No. 79), 8 pp., 4 maps, 2 columnar-sectiOn sheets, 190~. 

n:a e a series o srmi ar a titu. e . et~rmina- Taff, J. A., u. s. Geol. Survey Geol. Atlas, Tishomingo 

twns o~ a part of the Preston uplift m southern folio (No. 98), 8 pp., 3 maps, 1 columnar-section sheet, 

Marshall County, Okla., locally known as .the 1903. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 120 PLATE XVII 

96° 301 96°001 

GEOLOGIC MAP OF PARTS OF NORTHEASTERN TEXAS AND SOUTHERN OKLAHOMA 

Scale so~poo 

sE=c=~~~jo==========sE=========~lo==========llii=========~z ========~25 ~es 

1918 

Areal geolog\J b\J L. W. Stephenson, supplemented b\J data published by Hill, Taff, and Gordon, and b\j data furnished b\j 0. B. Hopkins, S. Powers, and H. M. Robinson 

Structure contours showing the altitude above sea level of the top of the Goodland limestone, b\J 0. B. Hopkins, S. Powers, and H. M. Robinson 

1!5°30' 

Structure contours showing the altitude of the base of the Ector tongue of the Austin chalk and the base and top of the Annona tongue of the Austin chalk, by 0. B. Hopkins and S. Powers 

• 

EXPLANATION 

·§ r. C=:J t Midway formation 

g and part of the Wilcox formation 

r:.;) (Sand and clay) 

}i 

·! 

"' 

~ 

UNCONFORMITY 

Navarro formation 

(Calcareous clay and sand) 

Taylor marl 

(Calcareous shaly clay) 

Pecan Gap chalk member, Ktp 

Wolfe City sand member, Ktw 

[~}-----------------~~~ Austin chalk 

Brownstown ~ marl 

(Calcareous clay) 

~ (Includes Ector tongue (a on map) and 

c.? Annona tongue (bon map). Includes 

Clay eqvivalent to part 

of Austin chalk on the 

west, and in part to the 

Blossom sand and 

Brownstown marl on the east 

Blossom sand 

(Calcareous glauco- nitic sand) 

~ 

~ 

also, for convenience of mapping, 10 to 35 feet of unnamed nonchalky cla1f. and 

sand, down to and including ths 'fishbed conglomerate ") 

Eagle Ford clay 

(Dark shaly clay) 

[;] 

Woodbine sand 

(Fine to coarse sand and cla11) 

UNCONFORMITY? 

f--Y.~:- ] Washita group 

(Includes in ascending order Kiamichi 

clay, Ducic Creek /ormation, Fort Worth limestone, and Denison/ormation. 

e, approximate outcrop of top of Fort Worth limestone) 

!': Fredericksburg group, c3 which in this area is represented 

by the Goodland limestone 

c::J 

Trinity sand 

(Fine sand and clay) 

The altitude of the tOP of the Goodland limestone where it is involved in ths Preston anticline is represented by ths contours in northsrn Grayson County, Teo:., and southern MarshaU 

and Bryan counties, Okla. 

The altitude of ths base of ths Ector tongue of the A us tin chalk is represented by the contours in ths vicinity of Ector and Ravenna, Fannin County, Teo:. Ths altitude of the base of ths Annona tongue of the A us tin chalk is represented by the contours within a few miles south, east, and northeast of Bonham, Fannin County, Teo:. The altitude of the top of the Annona tongue of the Austin chalk is represented by ths contours in ths vicinity of Leonard, Bailey, Gober, and Honey Grove, Fannin County, Teo:. 

[::J 

Locality at which fossils have been obtained 

from the Blossom sand. The figures indicate 

U. S. G. S. collection number 

Ul 

:::J 

0 

LJ.J 

u 

< 

fLJ.J 

0::: 

u 
GEOLOG'Y OF NORTH~~STERN 'r~XAS .t\.ND. ·SOUT:S:ERN OKLAHOMA. 131 

Veatch, A. C., Geology and un.derground-water resource~ 

of northern Louisiana and southern Arkansas: U. S. · Geol. 

Survey Ptof. Paper 46, 422 pp., 51 pls., 1906. ~ 

'Gordon, C. H., The chalk formations of northern Texas: 

Am. Jour. Sci., 4th ser., vol. 27, pp. 369-373, 1909. 

Taff, J. A., and Reed, W. J., The Madill oil pool, Okla,: 

U. S. Geol. SUl'vey Bull. 381, pp. 504-513, 1910. 

Gordon, C. H., Geol9gy and undergrou~d 'yat~re of po~theastern 'l'exas: U. S. Geol. Survey Water-Supply Paper 

276, 78 pp., 2 pis., 1911. · 

Shannon, C. W., and others, Petroleum and natural gas 

in Oklahoma: Oklahoma Geol. Survey Bull. 19,· pt. · 2, 

pp. 316-321, 1917. 

TOPOGRAPHY AND DRAINAGE. 

The area shown on Pia te XVII lies near the 

northwestern. border of the Gulf Coastal Plain 

in northeastern Texas and southern Oklahoma, 

and is a dissected coastal-plain upland ranging 

in altitude from about 530 feet in tho southeast 

to 850 feet in places in the northwest. The 

highest points in tho area· are between Denison 

and Pottsboro, Grayson County, Tex., where 

several hills rise slightly more· than 900 feet 

above sea level. Rod River, which crosses the 

area from west to ·east in a sinuous course near 

the northern margin, has cut a broad valley 200 

to 300 foot below tho.genoral upland, the altitude of low-water level whore the river enters 

tho area being approximately 590 feet and 

whore it leaves the area not quite 400 feet. A 

little loss than the northern half of the ar.ea 

is drained by tributaries of Eod River. In 

the east, south of the Red River valley, the 

drainage is carried by tributaries of Sui-. 

phur River,· which flows eastward .and joins 

Rod Eivor in Louisiana.. . The southern and 

southwestern parts of tho area are drained by 

numerous southward-flowing creeks belonging 

to tho Trinity River system. 

The drainagoways of tho area present many 

good examples of consequent, subsequent, obsoquent, and perhaps other classes of streams, 

a detailed description of which is outside the 

scope of this paper. Attention may be called, 

however, to the conspicuous development of 

small tributaries of South Sulphuf River, itself 

a subsequent stream, which flow down the 

gentle southward-facing slope of the cuesta 

formed by the Pecan Gap chalk in Delta 

County and ·the northeastern part of Hunt 

County, and the similar tributaries of North 

Sulphur ·River, also a subsequent stream, 

which flow southward on the corresp_onding 

slope of the cuesta formed by the Annona 

tongue of the ·Austin chalk in southern Lamar 

and F~nnin· .counties. (See p. 132 and Pl. 

XVII.). These ·are not consequent streams, as 

that term was. originally defined, in that their 

COJITses are not determined in consequence of • 

the original slope produced by -the uplift of the 

area fro~ beneath the sea, but rather in consequence of the southward. slope of the chalk and 

clay· ~o:rmatio;ns ·down fhose eroded surfaces 

they flow~· With the excep-tion of some of the 

smaller str.eams·in the terraced area along Red 

River .the drainage is almost completely adjusted_ to the structure· of the underlying Cretaceous formations, and in general the area 

affords an excellent example of maturely·adjusted drainage on ·only partly consolidated, 

unequally resistant rocks of gentle monoclinal 

attitude • 

. r];le area falls chiefly within the four physiographic divisions: 1 commonly known as the 

Black Prairies, tho Eastern Cross Timbers, the 

Gra:p.q Prairies, and theW estern Cross Timbers. 

The boupdaries separating these divisions are 

approx~mately coincident with the boundaries 

of underlying formations composed of unequally 

resistant. rocks, but these boundaries are not 

everywh~re sharply defined. Along Red River 

is·a belt of alluvial terrace plains of Pleistocene 

age (see p. 132), which I:anges in width from 2 

or 3. miles where the river enters the area, at 

the ·:west, to 15 miles or more in the northeastern part ~f the area and which may well be 

classed as a physiographic division. distinct 

from each of the four just enumerated. 

The Black Prairies embrace chi~fly the areas 

in Collin, Hunt, Delta, Lamar, Fann~n, and 

Grayson counties underlain by the marine 

chalks, clays, and marls of the Gulf series. 

(See geologic map, Pl. XVII.) Topographically these areas are characterize.d in the main 

by. nearly level to gently rolling surfaces, 

merging near Red River and the larger creeks 

into 4ills of moderate relief and smoothly 

rounded slopes. Cuestas of low relief have 

been prod11ced by the relatively resistant chalk . 

members of the series ~s described on a subsequent page. 

The Eastern Cross Timbers include the relatively narrow belt underlain by the Woodbine sand of the Gulf series (see Pl. XVII), 

which extends from the northwestern part of 

lllill, R. T., U. S. Geol. Survey Twenty-first Ann. Rept., pt. 7, 

pp. 6§-75, pl. 10, 1901. 
132 SHORTER CONTRffiUTIONS TO GENERAL GEOLOGY, 1918. 

Fannin County west by north through Gray- narrow along that ,part of the river bordering 

son County to th(l vicinity of Gordonville and Grayson County, Tex., but broadens out to 3 

thence south along the western border of the or 4 miles in places along the northern border 

area mapped. The belt is characterized by of Fannin and Lamar counties, Tex., and the 

' sandy hills of pronounced relief, supporting .a southern border of Bryan County, Okla. (2) 

growth of blackjack and post oak trees; a A well-defined river terrace 45 to 75 feet above 

good example is afforded by the hills within low-water level of Red River is moderately 

aeveral miles southwest and west of Denison, extensive in places along the river valley; the 

Grayson County. (S~e Pl. JCX;VI.) As shown village of Preston, in Preston Bend, in the 

elsewhere in this report, however, the Wood- northern part of Grayson County, is situated 

bine formation is irregularly bedded, and lo- on an exceedingly flat portion of this plain, 4 

cally considerable parts of it are composed of or 5 square miles in extent, and Woodville, 

clay which has produced a gently rolling sur- about 2t miles north of Preston, in Marshall 

face similar to that of the Black Prairies; such County, Okla., stands on a somewhat larger 

an area occurs along the central and southern portion of the plain. (3) A terrace plain 140 

parts of the belt of outcrop of this formation to 160 feet above water level is represented 

for a distance of several miles west-northwest here and there in that part of the valley above 

from Pottsboro, Grayson County. the mouth of Washita River but occupies exThe Grand Prairies include the area along tensive areas in the valley below that river; in 

the south limb of the Preston anticline in north- the southwestern part of Bryan County, Okla., 

ern Grayson County, Tex., and small areas along the alluvial deposits of this terrace form a flat 

the north limb of the anticline in Marshall sandy plain 8 miles or more in width from 

County, Okla., underlain by the limestones north to south, and large areas of the plain ocand shaly clays and marls of the Comanche cur in the northern parts of Fannin and Lamar 

series down to but not including the Trinity counties, Tex. (4) Remnants of surficial desand. (See geologic map, Pl. XVII.) This posits were observed at still higher altitudes at 

belt resembles the Black Prairies in its gently several places in the area and may represent 

rolling to moderately hilly aspect, but the in- one or more additional terraces. The alluvial 

durated layers of the Comanche series, includ- deposits on these terrace plains effectually 

ing in ascending order those of the Goodland, obscure the Cretaceous formations over many 

Duck Creek; Fort Worth, "Quarry," and Main square miles in the Red River valley, rendering 

Street limestones, tend to produce numerous it difficult to determine the areal extent and 

small benches and low cuestas in the other- structure of the formations. 

wise smooth to moderately rolling surface; Minor features of the topography that have 

these features are well exhibited· in Grayson an important bearing on the areal mapping 

County in the northward-facing· slope of the· and the determination of the stratigraphy and 

Red River valley, north of the belt of outcrop structure are the ridges, benches, and stream 

of the Woodbine sand. The belt of outcrop of bluffs produced by the more resistant strata of 

the sandy strata of the Pawpaw member locally both the Comanche and Gulf series. Many of 

produces a narrow belt of timbered, sat;!dy soil these features take the form of cuestas-that is, 

within the Grand Prairies, which resembles the broad, low ridges of great linear extent that 

Eastern Cross Timbers. · trend parallel to the strike of the rocks and 

The Western Cross Timbers are represented present long, gentle slopes to the east, southin this area c4iefly by a narrow belt that marks east, or south in the direction of the dip and 

the crest of the Preston anticline in southern short, steep slopes on the inland side, which 

Marshall County, Okla .. , west of Preston Bend marks the western edge of the outcrop of the 

of Red River, where the sandy strata of the harder ridge-forming strata. An example is 

'l"rinity sand come to the surface. Topographi- the white rock escarpment of Hill,t which 

cally the area is hilly and similar to that of the marks the western and northern edge of the 

Eastern Cross Timbers. Austin chalk in Grayson and Collin counties 

· The belt of alluvial terrace plains bordering and which makes a relatively steep ·descent 

Red River includes plains at . several levels: 

(1) The present flood plain of Red River is t Hill, R. T., U.s. Geol. Survey Twenty-first Ann. Rept., pt. 7, p. 

68, 1901. 
GEOLOGY OF NORTHEASTERN TEXAS AND SOUTHERN OKLAHOMA. 133 

from a portion of the Coastal Plain upland 

that is underlain by the Austin chalk to a belt 

of the upland that lies 75 to 100 feet or more 

lower and is underlain by the softer Eagle 

Ford clay. Similar examples are the relatively steep slopes that mark the northern 

edges of the Annona tongue of the Austin 

chalk in Fannin and Lamar counties and of the 

Pecan Gap chalk in Delta, Fannin, Hunt, and 

Collin counties. (See g¥ologic map, Pl. XVII.) 

GENERAL GEOLOGIC FEATURES. 

The Cretaceous deposits ar.e divisible into 

two great series, a lower, the Comanche series, 

which appears at the surface about the flanks of 

the Preston anticline in the northwestern part 

of the area and has an estimated thickness of 

800 to 1,000 feet, and an upper, the Gulf series, 

which has an estimated thickness of at least 

3,000 feet and the outcrop of which covers considerably more than half the area. Each of 

these series is separable into subordinate divisions, which are discussed on subsequent 

pages. The Gulf series is unconformably overThe area shown on the geologic map (Pl. lain by strata of Eocene age which appear at 

XVII) is underlain throughout its extent by the southeast in a relatively small part of the 

strata of Cretaceous age, which rest upon. a area under discussion. (See Pl. XVII.) In 

buried, moderately sn1ooth basement con1posed general the st.rike of the strata is parallel to the 

of ancient rocks. ~Just to .the north, in the inner margin of the Coastal Plain, and the dip 

Atoka and Tish01ningo quadrangles, Okla., is coastward from this margin at rates ranging 

where the basen1ent comes to the surface, it from 30 feet or less to 80 feet or n1ore to the 

·includes Paleozoic sedimentary rocks of Cam- mile. A considerable departure from the prebrian, Silurian, Devonian, and Carboniferous vailing regularity in strike and dip occurs in 

age and pre-Paleozoic granites. The upper the northwestern and central parts of the ar~a, 

surface of the basement rocks is believed to be a in connection with the Preston anticline, depeneplain for1ned by erosion prior to the de- scribed on pages 159, 160. A less pronounced 

position of the Cretaceous sediments upon it departure from the ·common monoclinal strucand subsequently tilted slightly coastward. ture is occasioned by the fold which produced 

The northern boundary of the Cretaceous the Leonard-Celeste monoclinal nose, described 

deposits trends about due west 10 to 30 miles on page 161. 

north of Red River, and the western boundary The Cretaceous deposits consist of sand, 

trends south by west through Montague, Wise, shaly clay, calcareous shaly clay, limestone, 

and Parker counties, Tex. Both these bound- and chalk. With the exception of the Trinity 

daries are outside the area shown on Plate sand (p. 134) and the Woodbine sand (p. 145), 

XVII. The tilted peneplained surface of the both of which were laid down in deltas and in 

basen1ent rocks dips t9 the south from the marginal marine waters, all these deposits are 

northern boundary at rates estimated to range of typical marine origin. 

in different places from 50 to 70 feet or n1ore to The boundaries of the formations as indithe nlile, and to the southeast fro1n the western cated on Plate XVII" are in part very much 

boundary at rates probably ranging from 40 to generalized.· Where they are established with 

50 feet to the mile. Within the area mapped approximate accuracy for the scale of the map 

the basement rocks lie nearest to the surface by the personal observations of the writer and 

beneath the crest of the Preston anticline, in his associates or by published evidence rethe southern part of Marshall County, Okla., garded as sufficiently reliable, the boundaries 

and the northern part of Grayson County, arc drawn as full lines. Elsewhere the bounclTex., where their depth ranges from 350 to 700 aries have been determined by general confeet; they lie deepest in the southeastern part siderations or by using the unverified boundof the area, where their depth is estimated as · aries indicated on n1aps of IIill, Taff, and . 

between 4,000 and 5,000 feet. Gordon and are drawn as broken lines. The 

The basement rocks are separated from the geologic formations of the northeastern part of 

overlying Cretaceous deposits by an uncon- Fannin County and the northern part of Lamar 

formity representing a long interval of geo- County are little known, owing in part to an 

logic time, including at least the Triassic and extensive covering of Pleistocene all1.1.vial torJurassic periods and probably a considerable race deposits which largely conceal the Orepart of the Lower Cretaceous epoch. taceous formations in a broad area bordering 
134 SHORTER CONTRIBUTIONS TO ·GENERAL GEOLOGY, 1918. 

Red River on t4e south, and in part •to the in- Comanche ·constitutes a closely related lithoadequacy: of the field work that has been done logic and paleontologic series. 

in the area. The writer has not examined .the 

boundary. between the Woodbine and ·E·acrle b 

Ford formations anywhere in western Grayson 

and eastern Denton counties, nor the boundary 

between the Eagle Ford and Austin south of 

the Texas Pacific Railroad in Grayson and Collin counties. ·The position assigned to the·Cretaceous-Eocene contact in Hunt and Hopkins 

counties is based chiefly on the maps of Hill 

and Gordon. 

CRETACEOUS SYSTEM. 

COMANCHE SERIES. 

GENERAL CHARACTER. 

The Comanche series consists of sands, shaly 

clays, marls, . and limestones having an estinlated. thickness in northeastern Texas of 800 

to 1,000 feet. The series. has been subdivided 

in Texas in ascending order into the Trinity, 

Fredericksburg, and Washita groups,, all of 

which are represented in the area treated in 

this paper. ·(See Pl. XVII.) In this area· the 

series appears in surface exposures only in .the 

northern part of Grayson County, Tex., and in 

an adjacent area north of Red River in the 

southern parts of Marshall and Bryan counties, 

Okla., where it has been brought to the surfac~. 

by the uplift that produced the Preston anticline. (See p. 159.) Were it not for this anti~ 

cline the series would lie buried beneath the 

Gulf series in the area mapped, with the possible exception of its extreme northwestern corner. Hill's classification of the· Comanche series in Grayson County is given in c·olumn C in 

Plate XVIII. . 

The Comanche series is of Cretaceous age. 

Until recently the series has been regarded by 

American geologists as belonging to the Lower 

Cretaceous, but for a number of years certain 

European geologists, notably Douville, 1 have 

regarded the series as in part Upper Cretaceous. Berry· ·and Knowlton 2 now correlate 

. the Was.hita, the uppermost group of the series, 

unquestiOnably with the Cenomanian (Upper 

Cretaceous). Whatever may be the position. 

of this series with respect to the standard European section, it is reasonably certain that the 

J Douville, H., Sur que!ques rudistes amerlcai~s: Soc.' gaol. France 

Bull., 3d ser., vol. 28, p. 218, 1900. · . 2 Berry, E. W., T~e. Upper Cretaceous floras of the world: Maryland 

Geol. Survey, Uppr.r Cretaceous, pp. 222, 223, 1916. 

TRINITY SAND. 

The Trinity group, which is represented in 

northeastern Texas chiefly by sand (the ''Ant~ 

lers sand" of Hill), is the basal division of the 

Comanche. series. According to well records 

this sand is 400 to 700 feet thick in the vicinity 

of Red River in Grayson County, Tex., and 

Marshall County, Okla. Taff, who studied it 

in the Tishomingo quadrangle, Okla., a few 

miles north of Grayson County, states that the 

formation consists of fine, compact incoherent 

sand and scattered lentils of sandy clay, with a 

basal conglomerate a few feet to 50 feet thick, 

which in the western half of the quadrangle is 

cemented with chalky white lime. 3 Pebbly 

lenses occur in the sand in places. · 

In the area under consideration the sand is at 

the .surface in the axial portion of the Preston 

ant,icline, .in an irregular belt having a maximum width of 7 or 8 miles, extending from a 

point several miles southeast of Rock Bluff, 

on Re.d River, to the northwest corner of the 

a~ea i~ 9klahoma, as shown on the geologic 

map. (Pl. XVII). Localities where the sand 

was ·examined are mentioned or briefly described below. 1

At Rock Bluff, Red River, 2t miles south of 

Preston or 8! miles northwest of Denison, 

G~ayson .County, ~ex. (s~e Pl. XIX, A), near· 

the axi.s of the Preston anticline, the upper 150 

feet <?f the Trinity is well exposed, as described 

in the followi~g section: 

Section at Rock Bluff, Red River, Grayson County, Tex. 

[Altitude at top of section estimated to be 690 feet above sea level.] 

Fredericksburg group (Goodland limestone): Feet. 

Hard massive limestone . . . . . . . . . . . . . . . . . . . . . . 10 

~~!t~~a:~--~~~~~~.-~~~~~~~} w~:~tbe:.h. ~- ~ -~{ ~ Trinity sand ("Antlers sand" of Hill): 

. Light-gray, mostly fine argillaceous irregularly 

. bedded compact sand, with subordinate 

lenses of fine sandy clay and some pebbly 

lenses; in the lower 30 feet are interbedded 

lenses of purplish clay having a maximum . 

observed thickness of 6 feet........ • • • • • • • . . 150 

163 

In a bluff of Red River 1! miles above Rock 

Bluff, 1i miles south by east of Preston, 30 feet 

3 Tafl', J. A., U.S. Geol. Survey Geol. Atlas, Tishomingo folio (No. 98), 

p. 6, 1903. 
U. S. OEQT,QOTCAr, SUl~VEY 

A 

Tishomingo qunclrnngle, Oklahoma 

Tnff, Tishomt~ folio (No. 98) 

BenninRton limestone ___ ••• ----------

Bokchito 

formot•on 

Caddo 

limestone 

Trinity :~and 

. 

B C 

Grnysori County, Texas 

Stephenson Hill, 21st Ann. Hept., Pt. VII 

-

1918 1901 

Grayson 

marl 

r:t-- ~ 

Pawpaw 

sandy 

member 

Trinity 

sand 

Pawpaw 

beds 

Antlers sands 

l,ROFESSIONAT, PAPER 120 PLATE XVIII 

0 

South of Brazos River 

in central Texas Hill. 21st Ann. Hept., Pt. VII 1901 

Del Rio clay 

Edwards 

limestone 

Comanche Peak limestone 

Walnut 

formation 

Paluxy sand 

Glen Rose formation (chiefly limestone) 

?---------1-------1 ?--------

Basement sands 

E 

Austin quadrangle 

~!t\~1~1~ <'~~. ~G) 1902 

Buda limestone 

Del Rio clay 

Georgetown 

limestone 

Edwards 

limestone 

Glen Rose formation (chiefly lirnestone) 

-------i-------1 

Travis Peak formation 

a.. 

::> 

e 

\Q.() 

'2? 

::> 

.0 

V) 

u 

·c 

~ 

~ l.1.. 

Feet 

1,100 

1,000 

900 

800, 

700 

600 

500 

400 

300 

200 

100 

0 

COllllELATION TABLE SHOWING THE HELATION Ol<' THE SUBDIVISIONS OF THE COMANCHE SERIES IN GHAYSON COUNTY, TEX., 

TO THE l"O.HMATIONS OF THE SAME SEHIE~ IN OTHEil PAllTS OF TEXAS AND OKLAHOMA. 
GEOLOGY OF NORTHEASTERN "TEXAS AND SOUTHERN OKLAHOMA. . 135 

of Trinity sand es~entially like that just described is exposed beneath 30 feet of Pleistocene terrace alluvium. 

In the public road 1! miles west of Preston 

30 or 35 feet of Trinity sand outcrops in the 

steep westward-facing slope of the Red River 

valley, and the Goodland limestone forms' a 

ledge at the crest of the hill, about 650 feet 

above sea level. Pebbly lenses were noted in 

the Trinity at this locality. 

At :Henderson Ferry on Red River, 4 n1iles 

west by south of Rock Bluff, the upper 40 feet 

of the Trinity is n1oderately well exposed and 

consists of fine to coarse gray and yellow sand 

with small mechanically included fragments of 

clay and slightly indurated sand. The sand is 

overlain by the Goodland limestone, including 

the Walnut member at its base, which is poorly 

exposed. 

Good exposures of the Trinity occur in the 

southern part of Marshall County, Okla., on the 

headwater branches of Sand Creek, 6 miles 

south by west of Kingston; in the valley of 

Buncmnbe Creek, 2~ to 8 miles north by east of 

W_illis Ferry; and in the valleys of Brier and 

I-Iouse creeks, 3 to 8 miles north and northwest 

of Willis Ferry. 

The northwesternmost locality where the 

Trinity was exmnined by the writer is on the 

northeastward-facing slope of the Red River 

valley about a n1ilc southeast of Orlena, in the 

extre:me northwestern part of Grayson County, 

Tex. . I-Iere the Goodland limestone caps the 

hill, forn1ing a rocky ledge at its crest at an 

altitude of about 750 feet, and 75 feet or more 

of the Trinity appears in the steep slope below 

the Goodland. 

South of the Red River region in Texas the 

middle portion of the .Trinity becomes calcareous, and south of Brazos River is seiJarable 

according to I-Iill 1 in ascending order into the 

base1nent sands, 127 feet; the Glen Rose formation, chiefly limestone, 315 feet; and the 

Paluxy sand, 190 feet. Still farther south, at 

Austin, the Paluxy sand is apparently represented 'Qy li1nestone in the upper part of the 

Glen Rose, so that the Trinity is separable in 

ascending order into only two parts-the 

Travis Peak form.ation, consisting of conglomerate, grit, sand, clay, and calcareous beds, 100 

feet; and the Glen Rose formation, chiefly 

llinestone, 450 feet. (See Pl. XVIII.) 

1 Hill, R. 'r., U. S. Goo!: Survey Twenty-first Ann. Rcpt., pt. 7, pp. 

153-154, 171, 1901. 

. FREDERICKSBURG GROtrP. 

GOODLAND LIMESTONE (INCLUDING. WALNUT SHALY 

MEMBER). 

The Trinity 8and is overlain by the Fredericksburg group, which in northeastern Texas 

is represented by the Goodland lin1estone, only 

13 to. 20 feet thick. The Goodland outcrops in 

a narrow area on the flanks of the Preston anticline, surrounding the area of outcrop of the 

Trinity sand (see· Pl. XVII), in northern Grayson County, Tex.,· and in southern Marshall 

and Bryan counties, Okla. Along the south 

side of the anticline the Gpodland dips south 

by west at rates ranging from 40 to 300 feet or 

more to the mile. The steepest laiown dip 

occurs about a mile and a half northeast of 

Pottsboro. (See structure contours, Pl. XVII.) 

The basal 3 to 6 feet of the Goodland lime:-

stone consists of layers of persistent hard thinbedded coquina-like limestone with interbedded 

thin layers of dark marly shale, which are in 

this paper called the Walnut shaly n1en1ber. 

These beds were not. recognized by I·Iill 2 in the 

type section ,at Goodland, in Choctaw County, 

Okla. He says: . 

Proceeding westward along the ancient Ouachita shore 

line fi:om Arkansas into Texas, the Exogyra texana beds 

(the ·walnut clays and Gryphaea breccia) are missing until 

the escarpment is reached north of Marietta, in the Chickasaw Nation [Love County, Okla.], where they first appear, 

thinly represented beneath the Goodland limestone. 

In 1894 3 and again in 1901 4 I-Iill restricted 

the ter1n "Goodland" tq the 1nassive li1nestone 

between the underlying Walnut clay, which 

he regarded as forming the upper part of the 

"Antlers" (Trinity) sand, and the overlying 

Kian1ichi clay. In the Atoka folio 5 and again 

in the· Tishon1ingo folio, 6 Taft inciuded the 

Walnut clay in the Goodland, and this usage 

has subsequently been followed by Taff. and 

other authors. Although the United States 

Geological Survey. has adopted Taff's usage of 

Goodland, the present writer is of the opinion 

that future investigations will demonstrate the 

appropriateness of restricting the application · 

of the name to the Dlassive limestone above 

the interbedded shaly clay and coquina-like 

limestone, here called Walnut shaly me1nber, 

in accordance with Hill's original usage. 

2 Geol. Soc. America Bull., vol. 2, pp. 502-514, 1891. 

a Geol. Soc. America Bull., vol. 5, pp. 303, 304, 189·1. 

• U.S. Geol. Survey Twenty-first Ann. Rept., pt. 7, pp. 216-222, 1901. 

& U.S. Geol. Survey Geol. Atlas, Atoka folio (No. 79), 1902. 

a Idem, Tishomingo folio (No. 98), 1903. 
136 S~ORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

Southward from Grayson and Cooke counties 

in Texas the Walnut member becomes thicker, 

and in Tarrant and Johnson counties it assumes 

the importance of a fo~mation rather than a 

member; here it consists of alternating hard 

and soft thin-bedded limestone and marl and 

reaches a maximum thickness of 140 or 150 

feet. Still farther south, in Hood and Somervell counties, the thickness again decreases to 

approximately 90 feet, and in the vicinity of 

Austin, Travis County, it is only 15 feet. 

(See Pl. XVIII.) The type locality of the 

Walnut member is at Walnut (or Walnut 

Springs), in Bosque.County. 

Above th'l.. .Walnut member the Goodland 

consists of 10 to 15 feet of hard massive persistent lime~tone, which weathers white. This 

limestone form.s conspicuous outcrops and is 

'therefore a valuable key rock in determining 

structure from surface ey...- •sure~. It is easily 

recognizable in well bc~-~de,d, its position so 

closely above the Trinity sand preventing its 

confusion with other limestones in the overlying Washita group. As a .rule, the drillers do 

not differentiate the few feet of limestone and 

marl of the Walnut member at the base of the 

Goodland li1nestone. Characteristi~_, fossils of 

the Goodland limestone are Gryphaea marco·ui 

Hill and Vaughan, Exogyra texana Roemer, 

Remondia robbinsi (White), Oerithium bosquense Shumard, and Schloenbachia acutocarinata (Shumard). The importance of the 

Goodland as a key rock warrants a fairly full 

description of its occurrence about the flanks 

of the Preston anticline. 

One of the easternmost outcrops of the 

Goodland near the crest of the Preston anticline is in the banks of ~ small creek entering 

Shawnee Creek just below the pumping station 

at the city lake, 4 miles northwest of Denison. 

The creek near its mouth is intrenched in the 

limestone to a depth of 6 to 7 feet, and the 

limestone is overlain by a few feet of alluvium. 

Upstream the top of the limestone gradually 

. becomes lower with respect to water level, and 

within a few hundred yards it passes beneath 

the bed of the creek. At Bears Ferry, Red 

River, 1! miles north by east of the city lake, 

the top of the Kiamichi formation is about· 25 

feet above water level, showing that the Goodland is here 15 or 20 feet below water level. 

Within a mile west of Bears Ferry the Goodland rises above water level and forms a gradually rising ledge in the northward-facing slope 

of the Red River valley westward. to Rock 

Bluff, where the base of the limestone lies a 

little more than 150 feet above the river. 

The section at Rock Bluff is described on 

page 134. 

West of Rock Bluff the Goodland appears in 

both slopes of the Little Mineral Creek valley, 

but its southward dip carries it below the surface in the bed of the creek at a point approximately 4! miles north of Pottsboro. A 

fine exposure of the limestone is afforded by a 

bluff on this creek 4! miles north of Pottsboro. 

(See Pl. XIX, B.) 

Section on Little Mineral Creek ·H miles north of Pottsboro, 

Grayson County, Tex. 

[Altitude at top of section estimated to be 615 feet ahove sea le_vel.] 

Fee~. 

Soil. . . . . . . • • • . . . . . . . . . . . . . . . . . . . . . . . . . . . • . • • • • • 2 

Fredericksburg group (Goodland limestone): 

.Massive limestone. . . . . . . . . .. . . . . . . . . . . . . .. .. 13 

Walnut shaly member: Hard thin-bedded 

coquina-like limestone containing Ostrea subovata Shumard, Gryphaea marcoui Hill and 

Vaughan, Trigonia sp., and Anomia sp., 

with interbedded thin layers of dark marly 

shale.................................... . . 6 

21 

Both the massive limestone and the underlying Walnut shaly member are well exposed 

·in a branch in the eastward-facing slope of 

Little Mineral Creek, 6 miles north of Pottsboro (3 miles north of Fink), where a thin 

eart,hy calcareous layer in which cone-in-cone 

stru.cture was well developed was noted about 

a foot below the top of the Walnut member. 

On the divide between Little Mineral Creek and 

Red River the Goodland extends northward to 

a point 7 miles· north of Pottsboro, where the 

altitude of its top is about 720 feet above sea 

level. The limestone here lacks less than 2 

miles of closing to the north over the crest of 

the Preston anticline, its absence in this interval being due to erosion which has removed 

the Goodland from the underlying Trinity. 

(See p. 137 and Pl. XVII.) 

At fienderson Ferry, Red River, 6t miles 

north by west of Pottsboro, the base of the 

Goodland is only 35 or 40 feet above water 

level, and upstream from the ferry, within an 

estimated distance of 1 or 2 miles, it finally 

comes down to water level and crosses into 

Oklahoma beneath the Pleistocene and Recent 

alluvial deposits of the Red River valley. 
U . S . GEOLOGICAL SURVEY PROFESSIONAL PAPER 120 PLATE XIX 

A. TRINITY SAND AND LOOSE SLABS OF GOODLAND LIMESTONE AT ROCK BLUFF (OLD 

MAilSHALL BLUFF) ON RED RIVER, 8),1 MILES NORTHWEST OF DENISON, GRAYSON COUNTY, 

TEX. 

The upper 150 feet of the Trinity is exposed in the blu!f. The Goodland limestone, which immedialely overlies 

the Trinity, forms a ledge along the crest of the bluff, and large m[\sses of rocks broken from it have fallen down 

the slope, giving rise to the name Rock Bluff. 

GOODLAND LIMESTONE ON LITTLE MI ERAL CHEEK I 

TEX. 

The massive Good land limestone is underlain by the Walnut sbaly ·member (the undermined portion). 
GEOLOGY OF NORTHEASTERN 1'EXAS AND SOUTHERN OKLAHOMA. 137 

Northwest of Henderson Ferry, in Marshall East of Preston the Goodland again crosses 

County, the southward-dipping limestone ap- the Red River valley beneath alluvial deposits; 

pears in the valley slopes of the southward- and although not traced in detail it was examflowing creeks tributary to Red River and was ined in an outcrop at the foot of a terrace 

especially noted along two small creeks respec- scarp at the edge of the Red River bottom 

tively 3 and 3t miles east of Willis Ferry. about half a mile north of Bears Ferry, in 

North of Willis Ferry the Goodland crops out. Bryan County, Okla. Here the top of . the 

in both the east ttnd west slopes of the ridge limestone is 30 or 35 feet above water le·vel. 

separating Buncombe and Brier creeks, and South of Red River in Cooke County, Tex., 

its continuity is interrupted at only one pla~e the Goodland gradually increases in thickness. 

on the crest of the ridge, where it 4as been It is regarded as the time equivalent of the 

eroded away. At a point estimated to be Walnut clay, and of the Comanche Peak and 

about 3t miles west by north of Willis Ferry Edwards limestones of centJ;al· ''rexas, which 

the Goodland again crosses Red River into south of the Brazos River valley have a comGray.son County, Tex., where, gradually rising bined thickness of over. 250 feet; still farther 

to the northwest in the northeastward-facing south the Edwards c•ntinues to thicken, being 

slope of the river valley, it finally forms the 300 feet thick in the vicinity of Austin, Travis 

crest of the hill overlooking the valley about County (see Pl. XVIII), and .520 feet thick 

a n1ile southeast of Orlena. The Trinity sand in Uvalde County, whereas the Walnut and 

appears in the slopes of this hill below the. Comanche Peak become thinner, the former 

Goodland. being only 15 feet and the latter 40 feet thick 

On the north limb of the Preston anticline in the vicinity of Austin. 

the Goodland crops out in the valley of Rock 

Creek south of Kingston, in Marshall County, WASHITA GROUP. 

0lda., and is especially Well exposed in a LITHOLOGY AND SUBDIVISIONS. 

branch about 3-! miles south by we.st of Kings- The Washita group con sis· s ehiefly of marine 

ton. The section here shows the upper mas- shaly clay, marl, and interbedded subordinate 

sive limestone, underlain by the Walnut shaly limestone, having a total estimated thickness in 

menlber, and this in turn by the Trinity sand. northern Grayson County of 415 feet; toward 

Down the valley of Rock Creek from this the top there is a sandy member, the Pawpaw 

locality the limestone appears in the south- (seep. 142), which is the only conspicuous exwestward-facing slope, gradually descending ception to the ~onsandy character of the group 

toward water level until, in· the vicinity of the in this area. The limestone, though subordibig bend a mile or two west of Woodville, it nate in thickness to the clay and marl, forms 

crosses the Red River valley beneath the several definite bands that have individual 

Pleistocene and Recent alluvial deposits and physical characteristics and contain index 

reappears on the Texas side of the river in the fossils which render them readily traceable 

hills in the northern part. of Preston Bend, th h t th th 1 1 b C \. d f h roug ou e area; ey 1ave a so een 

Grayson ;Ounty. 1 . goo ex~osure 0 t e approximately correlated by means of the foslinlestone wa.s noted In the pubhc road on the I ·l 'th b d. f d' · 1 . . SIs w1 e s o correspon Ing age In centra 

westward-faCing slope of the Red River valley cl th t 'I~ Th 1· t . . . . an sou wes ern exas. e 1mes ones are 1! m1les west of Preston, where It IS underlain tl f 1 bl k b d · d t · · tl 

by 30 or 35 feet of Trinity sand that outcrops lerle ~re vt a uta e feyth eels In .te ·erminmg le . . ~ . . geo ogw s rue ure o e eposi s. 

m the slope below the hmestone. 'Ihts locahty Th h b bel' 'd d b FI'lll d . . e group as een su IVI e y I an 

1s less than 2 miles north of the northernmost T ff 2 Alth h Hill' 1 t 1 t t 

occurrence of the limestone in the south limb a · . . <:>uallg s no~enc a w·a . rea -

f h · 1

. h d' 'd. b L' 1 mentis not In respects precise and consistent, o t e antic me on t e IVI e etween Itt e h · f b d 'b · M' 1 C k d R d R · (S ) t e successiOn o e s descn eel by him has been , mer.a ree ~ an e . Iver. ee P· 136: substantially verified. He recognized the fol-

'Ihe limestone here and In other outcrops In l · d' · · d · · d' d . . . . . OWing IVISIOns, name 1n ascen Ing or er 

thts v1c1mty clips to the northeast at an angle ( P.l XVIII) ( ) Th p t h d b . · . see . : a e res on e s su - suffiCient to carry It 40 or 50 feet below water ' 

level at Thomson Ferry, a mile north of Pres-· 1 u.s. Oeoi.Survey Twenty-first Ann. Rept., pt. 7, pp. 240-292,1901. 

2 U.S. Geol. Survey Geol. Atlas, Atoka folio (No. 79), 1902; Tishoton, Tex. mingo folio (No. 98), 1903. · 
138 SHORTER CONTRIBUTIONS -TO GENERAL GEOLOGY, 1918. 

divided into the Kiamitia clay, thickness 40 

feet, which rests upon the Goodland limestone, 

and the· Duck Creek fo~mation (clay, marl, 

and limestone), thickness 100 feet; (b) the 

Fort Worth limestone, thickness 35 feet; (c) 

the Denison beds, subdivided into (1) the 

Denton subgroup, thickness 45 feet; (2) the 

W eno subgroup, including the Marietta or 

Weno formation, thickness 115 feet; the 

Quarry limestone, thickness 2 feet; and the 

Pawpaw beds, thickness 45 feet; and (3) the 

Pottsboro subgroup, including the Main Street 

limestone, thickness 8 feet; and the -Grayson 

marl, thickness 25 feet. 

The divisions recognized by Taff in the 

Tishomingo and Atoka quadrangles, Okla., 

which correspond to the Denison beds of Hill, 

include in ascending order the Kiamichi formation, equivalent to the "Kiamitia" clay of 

Hill; the Caddo limestone, equivalent to the 

Duck Creek formation and the Fort Worth 

limestone; the Bokchito formation, equivalent 

to the Denton subgroup and the Weno subgroup (Marietta or W eno fonnation and Pawpaw beds) of Hill; and the Bennington limestone, equivalent to Hill's Pottsboro subgroup (Main Street limestone and Grayson 

marl). (See Pl. XVIII.) 

South of Grayson and Cooke counties, Tex., 

the Washita group, as a whole, becomes thinner,, at the same time gradually assuming a 

different lithologic character. In the Austin 

quadrangle (see Pl. XVIII) the Georgetown 

limestone, which is only 80 feet thick, appears 

to represent all of the Washita group of 

Grayson County up to and including the 

basal part of the Main Street limestone, a 

total thickness of at least 385 feet. However, 

the upper part of the Main Street limestone 

and the Grayson marl, which, together have a 

thickne-ss of about 30 feet, become thicker 

toward the 'south and are represented in the 

Austin quadrangle by the Del Rio clay and 

Buda limestone, which have a combined 

thickness of about 125 feet. 

'Hill's classification of the group is given in 

Plate XVIII (p. 134), which also includes columns showing the correlation with the subdivisions" of the group recognized· by Taff in 

the Tishomingo quadrangle, Okla., by Hill in 

the region south of the Brazos River valley, 

u.nd by Hill and Vaughan in the Austin quadrangle, 'Tex. In the· ··pres~nt report:. Hill's 

classification of the group, modified somewhat 

for the sake of simplicity and greater clearness, ·is adopted, as shown in Plate XVIII, 

column B. The changes include the dropping 

of the apparently unnecessary tern1s Preston 

beds, Weno subgroup, t..nd Pottsboro subgroup. 

KIAMICHI CLAY. 

The Kiamichi clay is named for Kiamichi 

River, on which it is typically exposed in 

Choctaw County, Okla. In Grayson County 

the Kiamichi clay, which includes all the beds 

between the Goodland and Duck Creek formations, is 40 or 50 feet thick and consists 

chiefly 9f dark carbonaceous shaly clay, with 

thin platy layers of siliceous limestone interbedded with the clay in the lower few feet and 

with thin layers of gray impure fossiliferous 

limestone in the upper 10 or 15 feet. The 

writer has not seen the full thickness of the 

formation, and the description is based partly 

on the statements of Taff and Hill. The section at Thomson Ferry, given below, which 

includes the upper part of the formation, was 

examined by the writer. (See Pl. XX.) 

This locality is on the north limb of the Denison anticline. 

Section at Thomson Ferry, on the right bank of Red River, in 

Grayson County, Tex., 2 miles south of Woodville, Okla. 

Duck Creek formation: Feet. 

Layers of limestone interbedded with subordinate layers of. dark shaly calcareous clay, 

the limestone hard and nodular in the upper 

part, softer and less nodular below, especially 

in the lower 2 feet. Fossils recognized: Kingena sp., Exogyra plexa Cragin, Plicatula sp., 

Gryphaea washitaensis Hill, Hamites jremonti 

Marcou (?), Schloenbachia (two or three 

species)................................... 15 

Kiamichi clay: 

Layers of gray impure, very fossiliferous ,limestone with thin interbedded layers of dark 

calcareous shaly clay; the limestone layers 

.contain vast numbers of Gryphaea, chiefly G. 

navia Hall. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3~ 

Dark shale with layers of Gryphaea-bearing 

limestone resembling the limestone .in the 

overlying division but more widely spaced. 

Fossils recognized: Gryphaea navia Hall, , 

Trigonia sp., and Plicatula sp.............. 7 

The Gryphaea-bearing limestones in the u·pper part of the Kiamichi clay are characteristic 

and persistent and form excellent key beds in 

determining the structure of the rocks in this 

area. They were noted also on t~e ; north 
'U. S . GEOLOGICAL SURVEY PROFESSIONAL PAPER 120 PLATE XX 

A. TOP OF KIAMICHI CLAY, OVERLAIN BY LIMESTONE MEMBER OF DUCK CREEK FORMATION, IN BLUFF ABOVE THOMSON FERRY, RED RIVER, 11 MILES NORTHWEST OF DENISON, 

GRAYSON COUNTY, TEX. 

B . SLABS OF GRYPHAEA-BEARING IMPURE LIMESTONE FROM THE UPPER PAHT OF THE 

KIAMICHI CLAY AT TI-lE LOCALITY SHOWN IN A. 

The shells belong chiefly to the species Gryphaea navia Hall. 
U . S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 120 PLATE XXI 

A. EARTHY FACIES OF THE LOWER •PART OF THE FORT WORTH LIMESTONE ON THE 

OKLAHOMA SIDE OF RED RIVER AT THE MISSOUlU, KANSAS & TEXAS HAlLWAY BRIDGE 

5 MILES NORTH OF DENISON, GRAYSON COUNTY, TEX. 

B. FOSSIL FUCOIDS (?) ON THE UNDER SIDE OF A SLAB 01" FOHT WOHTH LIMESTONE, AT 

THE LOCALITY SHOWN I A . 
GEOLOG;Y OF NORTHEASTE;RN TEXAS AND SOUTHERN OKLAHOMA. 139 

limb of the Preston anticline in a branch of f Section on Duck Creek and in a cut of the St. Louis & San 

I

:> 1 C k t bl' d 0 1

·ng 3 ml'les Francisco Railroad 2i miles north of Denison, Grayson :\.OC \: ree ~ a a pu lC roa cr ss ·. rv , rn · 

1: • l\K h ll C t vounty, .~.ex. south by west of .1(1ngston, CJ.ars a oun y, 

Olda. On the south limb of the anticline they 

were examined along the Preston road a short 

distance south of Rock Bluff (seep. 134); along 

the road leading down to I-Ienderson Ferry, 

5! miles north by west of Pottsboro; and in 

the be<t of Little Mineral Creek, 3! miles north 

of Pottsboro. 

DUCK CREEK FORMATION. 

The Duck Creek formation, which is typical! y exposed on Duck Creek north of Denison, 

in Grayson County, consists of approximately 

100 feet of limestone and gray to greenish-gray 

shaly calcareous clay, which intervene between 

the Kiamichi clay below and the Fort Worth 

limestone above. In the lower 35 or 40 feet 

the.limestone alternates with the clay in layers 1

6' to 12 inches thick, in about equal proporthms; in the upper part of the sec.tion ~he clay 

predominates, the limestone layers being rather 

sOft and separated by intervals of 2 to 3 feet 

or n1ore of clay. The limestones in the lower 

35 or 40 feet are characterized by keeled and 

nonkeeled ammonites, many of which reach 

a diameter of 2 feet or more. One layer of 

white, chalky limestone 3 or 4 feet thick 35 or 

40 feet above the base of the formation and 

2 or 3 feet of gray calcareous clay that immediately underlies it contain great numbers of 

large ammonites and form a zone that has 

been recognized in outcrops over a large area 

in Texas and Oklahoma and was used by 

Messrs. I-Iopkins, Powers, and Robinson as a 

key ip. the determination of structure. The 

keeled ammonites ·belong chiefly to the genus 

Schloenbachia, several species of which have 

been differentiated. The nonkeeled forms belong chiefly to the species Pachydiscus brazoensis (Shumard). The limestones also contain some of the remains of the problematic 

organisms (fucoids ~), such . as occur in great 

numbers and of larger size in the Fort Worth 

limestone. (See p. 140 and Pl. XXI, B.) The 

most complete section of the Duck Creek formation examined by the writer is on Duck 

Creek and in a .cut of the St. Louis & San Francisco Railroad where it comes close to Duck 

Creek, 2! miles north of Denison. . 

Fort \Vorth limestone: 

Four or five layers of nod·.llar impure argillaceous fossififerous limEstone interbedded 

with gray shaly clay •.................•.... 

Duck Creek formation: 

Gray shaly calcareous clay with interbedded 

layers of impure non ledge-forming limestone 

at intervals of 2 or 3 feet .................. . 

Concealed .................................. . 

Greenish-gray calcareous clay from which 

weather numerous specimens of Plicatula cf. 

P. incongrua Conrad and small rusty ammonites, probably the young of Pachydiscus and 

Schloenbachia, also a few specimens of Gryphaea washitaensis Hill ..................... . 

Ledges of limestone with interbedded layers 

of gray shaly clay, poorly exposed; the limestone, especially one layer near the top, contains numerous keeled and nonkeeled ammonites, many of which a'I'e of large size 

(maximum, 2 feet in diameter) ............ . 

Alternating beds of ammonite-bearing limestone 

and gray shaly clay, about half and half, 

Feet. 

8 

22 

20 

15 

20 

well exposed in bluff along the creek. . . . . . . 20 

Other expos tires of the limes tones forp1ing 

the lower part of the Duck Creek formation 

were observed by the writer in a small branch 

of Little Mineral Creek at the crossing of the 

road leading to Henderson Ferry, 4! miles 

north of Pottsboro; in the road leading down 

to Henderson Ferry about a mile west by 

north of the locality just mentioned; and at 

Willis Ferry (Oklahoma side), 13 miles northwest of Pottsboro, Tex. The upper part of the 

Duck Creek, consisting of calcareous clay, 

which lacks conspicuous layers of limestone, 

is well exposed in a bluff on the north side of 

Red River, about half a mile above Willis 

Ferry. These localities are on the south 

limb of the Preston anticline; the section at 

Thomson Ferry, on the north limb of the anticline described on page 138, reveals the basal 

15 feet of the limestone. 

FORT WORTH LIMESTONE. 

The Fort Worth limestone, named from the 

city of Fort Worth, Tarrant County, Tex., • 

consists in the vicinity of Red River north of 

Denison,. Grayson County, of about 25 feet of 

gray nodular earthy limestone interbedded 

with layers of dark shaly clay, followed above 

by 8 to 10 feet of heavy-l)edded hard cream-
140 SHORTER CbNTR.JBUTIONS TO GENERAL GFOLOGY, 1918. 

colored chalkJ limestone. Thi\3 limestone resembles the limestone portion of t~e unde:r;lying 

Duck Creek formation, from which it may be 

distinguished by slight lithologic differences, 

by the more comn1on occurrence of pectens, 

by the presence of echinoids in greater number 

among which are Hemiaster elegans Shumard, 

Exogyra walkeri White (a large smooth species), 

Nautilus texanus Shumard, and Schloenbachia 

leonensis Conrad. 

DENISON FORMATION. 

and Of larger size, ·and by the greater abun- DENTON CLAY MEMBER (INCLUDING "OSTREA CARINATA 

dance and 'd BED"). larger size of the problematic fuc01 -

like remains described below. The Fort Worth 

is immediately overlain by the Denison fornlation. A good exposure of the lower 25 feet of 

the formation is afforded by the bluff of Red 

River at the north end of· the bridge of the 

Missouri, Kansas & Texas Railway 5 miles 

north of Denison, on the north limb of the 

Preston anticline. (See Pl. XXI, A.) Here the 

impure nodular limestone layers range in 

thiclmess from a few inches to 2 feet, and the 

interbedded shaly clay con1poses half or more 

of the bulk of the material. The limestone 

layers are fossiliferous and the most numerous 

and conspicuous forn1s are keeled ammonites, 

some of which have a maximum diameter of 

18 inches, and echinoids. An interesting and 

characteristic feature of these limestones is 

the problematic fucoid 0) remains or casts of 

borings ( ~) which line the underside of some 

of the limestone layers. Good examples are 

shown in Plate XXI, B. The upper part of 

the formation is well exposed in the bank of a 

small branch about a third of a mile northeast 

of the Missouri, Kansas & Texas Railway 

bridge just east of the railway track; here 

the Fort Worth is overlain by 15 feet of reddish 

terr,ace sand. 

The upper heavy-bedded cream-colored limestone of the Fort Worth is exposed at many 

places on the south limb of the Preston anticline in Grayson County and was observed 

in a cut of the Missouri, Kansas & Texas Railway 2 miles north by east of Denison; on the 

Bears Ferry road 1 t miles in an air line northwest of the post office at Denison; on the 

Preston (Rock Bluff) road 31 miles north of 

the Missouri, Kansas & Texas Railway, near 

the head of a branch of Little Mineral Creek; 

on the public road 2! miles in an air line 

northeast of Pottsbcro; and on the Henderson 

Ferry road 31 miles north of Pottsboro, an 

eighth of a mile north of Fink. This upper 

massive part of the Fort Worth limestone conHill 1 originally applied the name Marietta to 

beds, chiefly shaly clays, 160 feet thick, between the Fort Worth limestone below and imperfectly defined so-called North Denison sands 

above. Later he reclassified the Denison formation, as shown in Plate XVIII, column C, 

introducing the name Denton subgroup, from 

Denton Creek, Denton County, for the lower 

45 feet of the original Marietta, including 

the "Ostrea car·inata bed" at its top, and 

applying the name Weno formation to 

the beds which lie between the Deriton 

and the· "Quarry" limestone and include 

most of the upper part ,of the original 

Marietta. In one of his tables in the same 

paper 2 he somewhat loosely applied the name 

Marietta to the beds between the Den~on and 

Pawpaw divisions. As the name Marietta is 

preoccupied for sandstone in the Dunkard 

group of Pennsylvania, West Virginia, and 

Ohio, its use in the Denison section seems 

undesirable. 

The lower 5 feet of the Denton is a strongly 

calcareous clay of a decided marly charactel'. 

This is followed by 35 feet of shaly, less calcareous clay, which in turn is followed by 3 to 5 

feet of highly fossiliferous impure limestone, 

composed largely of the shells of Gryphaea 

washitaensis Hill but containing also a few 

large echinoid spines and other foss~ls, among 

which are considerable numbers of Ostrea carinata Lamarck, a fossil which suggested the 

name 11 0strea carinata bed." The Denton 

member appears in imperfect exposures along 

the St. Louis & San Francisco Railroad 1! to 

2 miles north of Denison. 

The 11 0strea carinata bed'~ appears in many 

small exposures along the south limb of the 

Preston anticline and is an excellent key rock, 

chiefly because of the presence .of 0. carinata 

Lamarck, a peculiar and easily recognizable 

fossil. This stratum is exposed on the St. 

. · b d · · ts 1 d 1 Hill, R. T., Geol. Soc. America Bull., vol. 5, p. 303, 1894. stltutes a good key ~ ' OWing t~ I. e ?e- 2 Hill, R. T., U.S. Geal. Survey Twenty-first Ann. Rapt., pt. 7, p. 

formin(J' character and Its characteristic fossils, lus, 19o1. b 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 120 PLATE XXIl 

A. UPPER PART OF THE WENO CLAY IN Tim EAST BANK OF WASHITA RIVER AT THE 

FRISCO HAILROAD BHIDGE 2}4 MILES WEST OF PLATTER, BRYAN COUNTY, OKLA. 

The material exposed in the bank comprises shaly clay and subordinate interbedded layers of sandstone. 

B. UPPER PART OF THE WENO CLAY IN A CUT OF THE FRISCO H.AILROAD A MILE NOHTJ! 

OF THE STATION AT DE ISO , GRAYSON COUNTY, TEX. 

A ledge of the "Quarry .. Limcst.one, which overlies the 'Vcno, appears at. the extreme top of the sect.ion. 
U . S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 120 PLATE XXIII 

A. MAIN STREET LIMESTONE IN A CUT OF THE MISSOURI, KANSAS & TEXAS RAILWAY 

3 MILES WEST OF THE STATION AT DENISON, GRAYSON COUNTY, TEX. 

B. "QUARHY" LIMESTONE, U DEB.LA!N nY Til ~ WENO CLAY. IN A CUT OF THE FRISCO 

RAILROAD THREE-QUARTERS OF A MILE OH.TH OF DE !SON, GllAYSO COU TY, TEX. 
GEOLOGY OF NORTHEASTERN· TEXAS AND SOUTHERN OKLAHOMA. 141 

Louis & San Francisco Railroad 1! miles north 

of Denison and was seen also on the Missouri, 

Kanse,s & Texas Railway 1 i miles north of 

Denioon; on the Hears Ferry road about '1! 

ntiles in an air line northwest of the post office 

at Denison; in the headwater branches of Shawnee Creek, 3! miles west by north of the post 

office at Denisop.; and at Fink post office, 3 

miles north of Pottsboro. Messrs. Hopkins 

and Powers noted outcrops of a stratun1 that 

carries 0. carinata La;marck and apparently 

represents the "Ostrea carinata bed" stratigraphically 55 feet above the Fort Worth limestone, at two localities on the north limb of the 

anticline in Marshall County, Okla., namely, 

3! miles southeast of Kingston, in the NE. 

! sec. 3, T. 7 S., R. 6 E.; and 2~ miles east of 

Kingston, in the SE. i sec. 28, T. 6 S., R. 6 E. 

WENO CLAY MEMBER. 

The Denton clay member is overlain by 115 

feet of dark-gray shaly clay with subordinate 

thin. partings, lenses, and layers of fine gray to 

yellow sand, some of which are indurated to 

ledge-forming sandstone. To this material 

Hill 1 gave the name Weno formation, from the 

small village of W eno, on Red River 5 miles 

northeast of Denison, ·Grayson County, which 

does not appear on recent maps and is apparently abandoned. Jiill in the same paper also 

used the narp.e Weno in a broader ("subgroup") sense, to include both th9 Weno clay 

member and the overlying Pawpaw sandy 

member, a usage not followed in the present 

paper. Sand layers are numerous, th')ugh subordinate to the clay, in the upper 35 feet of the 

division in cuts of the St. Louis & San Francisco Railroad about a mile north of the station 

at Denison (see Pl. XXII, B), where one lens 

has a maximum thickness of 1! feet. At the 

same locality the clays contain many small 

flattish ferruginous concretions, probably derived by oxidation from concretions of iron carbonate, and some small concretions of marcasite. Fossil pelecypods and gastropods in a 

good state of preservation are numerous in the 

clays, sands, and ferruginous concretions in 

these upper beds, among which were recognized Nuc:ula sp., Ostrea quadriplicata Shumard, Protocardia texana (Conrad), Oyprimeria 

1 Hill, R. T., U.S. Geol. Survey Twenty-first Ann. Rapt., pt. 7, PP. 

121, 27f, 1901. 

sp., Oorbula (three species), Oymbophora sp., 

Turritella sp., Auchura mudgeana White, Engonoceras serpentinum (Cragin). 

The Weno clay weathers down to smooth 

surfaces and is as a rule poorly exposed on the 

uplands and valley slopes. In addition to the 

section in the railroad cut just described, a 

·good exposure of strata believed to represent a 

portion of the Weno clay and certainly representing either this clay or the Pawpaw mernber 

is afforded by Carpenters Bluff, on Reel River 

below the bridge of the ~1issouri, Oklahoma & 

Gulf Railway, 7 miles in an air line du.e east of 

Denison. Hill mapped the area in which this 

bluff is included as belonging to the Woodbine 

formation, though Taff had at an earlier date 

recognized that the outcrop at the bluff be-· 

longed to the Washita group. This exposure 

is about on the southeastward-plunging axis of 

the Preston anticline. 

According to Messrs. Hopkins and Powers 

the Weno clay in the north limb of the Preston 

anticline in Marshall County,· Okla., is about 

135 feet thick, or 20 feet thicker than in the 

south limb in Grayson County, Tex. A fine 

exposure of the upper 50 feet of the Weno, 

overlain by the ''Quarry" limestone, is afforded 

by a bluff on the 1eft bank of Washita River at 

the crossing of the St. Louis & Sau Francisco 

Railroad 2! miles west of Platter, Bryan 

County, Okla. A view of this bluff, taken at 

a low stage of water, is shown in Pl. XXII, A. 

The beds here consist predominantly of greenish 

shaly calcareous clay, with an interstratified 

layer of sandstone 5 or 6 feet below the 

"Quarry" limestone and several layers of thin 

flaggy sandstone 25 to 40 feet below the 

''Quarry.'' Well-preserved fossil shells, many 

species ·Of which are identical with those colJected in a cut of the St. Louis & San Francisco 

Railroad a mile north of Denison in Grayson 

County, Tex., are abundant in some layers of 

the clay and in some of the indurated layers. 

Several well-pres~rved fragments of crustaceans 

were found in the talus. 

Ab~ut 20 feet of dark shaly clay of the Weno 

:q:1ember, containing poorly preserved fossils, is 

well exposed in the)eft bank of a branch just 

east of the Missouri, Kansas & Texas Railway, 

1! miles south of Colbert, Bryan County, Okla.; 

this locality also is on the north limb of the 

Preston anticline. 
142 SHORTER CONTR.ffiUTIONS TO GENERAL GEOLOGY, 1918. 

PAWPAW sANDY .MEMBER (INCLUDING "QUARRY" way .about 2! miles east of Denison; at a 

LIMEsTONE). : culvert of the Missouri, Oklahoma & Gulf RailThe W eno clay member is overlain by ap- way about 2· miles east of Denison; in a northproximately 50 feet of more or less irregularly south public road 1! miles east by north· of 

bedded clays and sands, including at the base Pottsboro; in an east-west road at two ·creek 

a persistent layer of sandy limestone 1 to 4 feet crossings 2 miles north of Pottsboro; in the 

thick, known as the "Quarry" limestone. Cal- Henderson Ferry road 2! miles north of Potts-

. careous clay predominates in the lower half of boro, a quarter of a mile south of Fink; and in 

the division above. the "Quarry" limestone, and the public road a quarter of a mile west of 

sand and interbedded laminated sand and clay Fink. 

predominate in the upper half. Good expo- On the north limb of the Preston anticline the 

sures, particularly of the upper part of the "Quarry" limestone outcrops at the crest of the 

member, occur in the headwater branches of steep part of the bluff on Washita River at the 

Pawpaw Creek within the corporate limits of crossing of the St. Louis & San Francisco Railthe eastern part of Denison. way in Bryan County, Okla. (seep. 141), where 

The "Quarry" limestone is a sandy bluish- it overlies the Weno clay and is overlain in turn 

gray limestone that weathers yellow and purple by clays and sands of the Pawpaw member. 

and contains considerable numbers of Ostrea- Poor exposures were also noted near the public 

quadriplicata Shumard. 08trea subovata Shu- road leading to Kingston, about 3 miles northmard is rather sparingly represented. A good west of Woodville, in Marshall County, Okla. 

exposure is afforded by a cu·t of the St. Louis Messrs. Hopkins and Powers state that in the 

& San Francisco Railway three-quarters of a latitude of Kingston and farther north there is 

mile north of the station at Denison (see Pl. no definitely recognizable "Quarry" limestone, 

XXII, B), where it is 2 feet thick and the lower but several beds resembling it; 3 miles east of 

3 to 12 inches is conglomeratic. The somewhat Kingston they examined a section which inscattered pebbles in the conglomeratic portion eluded four distinct layers of .sandy- limestone 

consist of waterworn calcareous sandstone, each rese:I:nbling the "Quarry" and- each co.p.-

sandy limestone, and calcareous and ferrugi- taining Ostrea quadriplicata Shum~:rd. Mr. 

nous concretions, the largest 3 inches or more Hopkins noted an outcrop of a sandy glauconitic 

in length. A few borings into the top of the limestone resembling the "Quarry,· 4 miles 

underlying Weno clay, filled with material char- east of Kingston, Marshall County, in the cenacteristic of the limestone, were noted. As the ter of the west line of sec. 35, T. 6 S., R. 6 E., 

base of the limestone is sharply separated from from which he obtained a specimen of a bryothe underlying clay and is somewhat undulat- zoan which R. S. Bassler refers to the genus 

ing, the contact appears to mark an uncon- Domopora. 

formity, though the time represented by it was The section described below shows the relaprobably short. The limestone in this section tion of the Pa,·vpaw member to the overlying 

is overlain by 4 feet of clay, above which is an- Main Street limestone member. (See Pl. 

other layer of similar lin1estone 6 inches to 1 XXIV, B.) 

foot thick, which shows the lenticular charac- Section in a small headwater branch of Pawpaw Creek .Just 

ter of the rock and which apparently connects east of the subway under the Missouri, Kansas & Texas 

the "Quarry" limestone more closely with the Railway south of the station at Denison, Tex. 

overlying Pawpaw member than with the un- Main Street limestone member: 

derlying W eno clay. In this connection it may 

be mentioned that Messrs. Hopkins and Powers 

have noted in Marshall County, Okla., several 

layers of sandy limestone in the Pawpaw member that resemble the "Quarry." 

Other outcrops of the limestone were examined in Grayson County in the bed of a small 

branch of Smith Creek just south of the Missouri, Oklahoma & Gulf Railway, 4! to 5! 

miles east of Denison; in a ditch and in a field 

south of the Missouri, Oklahoma & Gulf RailIrregular nodular layers of hard limestone 6 to 

18 inches thick, interbedded with soft yellow 

marl a few inches to 6 inches thick; the under 

side of the lowest limestone layer is roughly 

nodular. Exogyra arietina Roemer nccurs 

abundantly in the upper 2 or 3 feet ........ . 

Gray, faintly laminated sandy and calcareous 

(marly) clay, coarsely sandy in the basal few 

inches; in the basal 6 inches are numerous 

small ferruginous concretions and a few flattish, partly oxidized iron carbonate concretions; one apparently water-worn quartzitic 

sarndstone pebble was noted .....••••••••••.. 

Feet. 

8 
U. S . GEOLOGICAL SURVEY PROFESSIONAL PAPER 120 PLATE XXIV 

A . WOODBINE SAND IN A CUT OF THE MISSOURI, KANSAS & TEXAS RAILWAY l .Y:l MILES 

WEST BY SOUTH OF THE STATION AT DENISON, GRAYSON COUNTY, TEX. 

The Woodbine here is a partly indurated ferruginous sand, containing irregularly distributed thin ironstone plates. 

B . MAIN STH.EET LIMESTONE UNDEH.LAIN BY THE PAWPAW SANDY MEMBEH. OF THE DENISON 

FOH.MATIO NEAH. THE SUBWAY SOUTH OF THE MISSOUH.I, KANSAS & TEXAS HAlLWAY 

STATION AT DENISON, GH.AYSON COUNTY, TEX. 

The Pawpaw member, as exposed at this locality in a headwater branch of Pawpaw Creek, comprises laminated crossbedded sand and clay. 
U. S . GEOLOGICAL SURVEY PROFESSIONAL PAPER 120 PLATE XXV 

A . SAND AND CLAY OF TI-lE WOODBINE FORMATION AT HYATTS BLUFF, ON RED RIVER 

5 MILES NORTHWEST OF RAVENNA, FANNIN COUNTY, TEX. 

B. FERRUGINOUS SAND OF THE WOODBINE FORMATION IN THE SHERMAN ROAD, 2 MILES 

SOUTHWEST OF DENISON, GRAYSON COUNTY, TEX. 
• 

GEOLOGY OF NORTHEASTERN TEXAS AND SOUTHERN OKLA:E(OMA. 143 

Unconformity (?). 

Pawpaw sandy member: 

1'hinly laminated, strongly cross-bedded gray 

clay and sandy clay with thin sand partings 

and some larger lenses of fine yellow sand; 

. numerous thin iron crusts occur in the partings; some comminuted plant fragments 

Feet. 

were noted................................ 6 

'l'he upper 6 feet of the Pawpaw is also well 

exposed beneath the Main Street limestone on 

the Missouri, Kansas & Texas Railway at the 

iron overhead bridge 3 miles west of the station 

at Denison. (See below and Pl. L~III, A.) 

I-Iere the Pawpaw consists of current-bedded, 

lan1inated sand and clay with highly fossiliferous thin lenses of ferruginous oxidized soft 

sandstone. Among the fossils recognized were. 

Nucula sp., Protocardia texana (Conrad), Oymbophora sp., OoTbula sp., A nchura mudgeana 

White, and Engonoceras serpentinum (Cragin). 

The Pawpaw member produces a narrow belt 

of sanely soil between the clay soils of theW eno 

and those of the overlying :Main Street limestone and the Grayson n1arl. The topography 

produced by the sandy beds of the Pawpaw is 

similar to that characteristic of the o:utcrop of 

the Woodbine fonnation of the Gulf series. 

MAIN STREET J,IMESTONE lllEliiBER. 

The Main Street limestone, named from exMain Street lim!3~tone member-Continued. 

Greenish-gray sandy calcareous clay marl with 

scattered white clay pebbles and ferruginous 

concretionary clay nodules along the base, 

some of which suggest having been mechaniFeet. 

cally included ....•••.•.....•.••••••••••..• lt-12 

Unconformity (?). 

Pawpaw sandy member: 

Current-bedded greenish-gray fine sand, with 

fine clay lamina~ and subordinate lenses of 

la'llinated clay. Highly fossiliferous thin 

discontinuous lenses of ferruginous oxidized 

soft sandstone with many molds and internal 

casts of fossil mollusks; soft molds and internal casts occur also in the soft sands. (See 

list, above.) Maximum exposed thickness .. 6 

The limestone is poorly exposed on Main 

Street east of the rai.lroad tracks in the eastern 

part of Denison and is well exposed in some of 

the branches and o:q. the slopes about the headwaters of Pawpaw Creek in the san1e vicinity.· 

One section is described on page 122. (See 

also Pl. XXIV, B.) 

Other exposures of the limestone were noted 

along the south limb of the Preston anticline 

in Grayson County, in the bed of a headwater 

branch of Iron Ore Creek just north , of th£' 

Missouri, Kansas & Texas Railway, 5! miles 

west of the station at Denison and a quarter 

of a mile east of a north-south public road; 

poor exposures showing dips of 20° or more 

posures on Main Street in Denison, consists, in . . In a ~ow strike ridge extending from a point 2 

Grayson County, of 8 to 20 feet or more of miles east of Pottsboro northwestward for a 

heavy-bedded hard limestone, with subordi- distance of 2 mile.s; in the bed of a headnate interbedded layers of unconsolidated cal- water branch of Little Mineral Creek on the 

careous marl,· and is. characterized by the Hender~on Ferry road 2~ n1iles north of, Pottspresence of Exogyra arietina Roemer, p~rticu- boro, seven-eighths of a mile south of Fink; 

larly in the tipper part, and of l{ingena waco- poor exposures along the east-west public road 

ensis (Roemer) in the lower part. One of the three-fourths of a mile to 1 ~ miles west of 

best exposure~ of t~e limeston~ is afford~d .by Fink; on the same road near the heads of 

a cut of the Missouri, Kansas & Texas Railway · 21 2J.. 2.a d 3J.. ·1 t f F' k . . D . ravines 4 , 'I' 4 , an g- mi es wes o In , 3 miles west of the statwn at enison. (See 1 · b th G . 1 h' h Pl. L~III A.) ?ver am y e rayson n1a~, w IC appears 

' . lin several poor exposures; In the bed of a 

Section in cut of J.~issouri, K~nsa$ & Texas Railway 3 miles s1nall southward-flowing branch of Mill Creek 

west of the statwn at DemsorJ., Grayson County, Tex. about 4 miles west by north of Fink; along a 

Residuum and creep: Feet. north-south public road 2 miles east by south 

Brownish loam containing in places along its of Cedar Mills; on a public road on the westbase a great number of ferruginous sandstone 

fragments and boulders derived from the ward-facing slope of the Mineral Creek valley 

Woodbine sand.. . . . . . . . . . . . . . . . . . . . • . • . • . • 2-6 1 ~ miles east . y ·south of Cedar Mills; in a 

Main Street limestone member: small branch at the turn of the road just south 

Irregular layers of limestone 3 to 4. feet thick, of Cedar Mills; on the northward-facing slope 

with discontinuous interbedded lenses of soft of the Sandy Creek valley just north of Cedar 

marl, underlain by 3 to 4! feet of massive · hard limestone having an undulating nodular Mills; at the crossing of a public road over a 

base; Exogyra arietina Roemer is common in headwater branch of Brier Creek 5 miles norththe upper layers............................ 7! west of Gordonville; and on the southeast 
144 SHORTER CONTRIBUTIONS TO GENERAL GEO:J:.OGY, 1918. 

crest of Brushy Mound, 9 miles northwest of 

Gordonville. 

The Main Street limestone was not seen in 

place by the present writer on the north limb 

of the Preston anticline, but Messrs. Hopkins 

and Powers state that they have seen it well 

exposed at the following localities in Oklahema: In Bryan County on the south bank of 

Rock Creek along the public road, 2 miles 

northwest of Platter; and in Marshall County 

a mile west of Washita River; on the south 

bluff of Washita River at the southeast c·orner 

of sec. 7, T. 7 S., R. 7 E.; 2 miles northeast of 

Woodville, in the center of the east line of 

sec. 19, T. 7 S., R. 7 E.; and 4 miles north of 

Woodville, in the NW. ! sec. 1, T. 7 S., R. 6 E. 

According to the geologic map of. the Tisho-, 

mingo quadrangle, which ·joins the Denison 

quadrangle on the north, the Bennington 

limestone of Taff, which includes the Main 

Street limestone, enters the Denison quadrangle 2 or 3 miles west of its northeast corner. 

GRAYSON MARL MEMBER. 

GULF SERIES. 

GENERAL CHARACTER. 

The Gulf series is composed of sands, shdy 

clays, chalks, and calcareous clays and sands 

(marls), which have an estimated thickness of 

approximately 3,000 feet in· the area under 

consideration. In the southwestern part of 

the area the succession of formations in the 

series is, in ascending order, as follows: Woodbine sand, Eagle Ford clay, Austin chalk, Taylor marl (including the Wolfe City and Pecan 

Gap members; see pp. 155-156), and Navarro 

formation. Toward the north the lower part 

of the Austin chalk merges, with some intertonguing, into contemporaneous· nonchalky 

sands and clays, and the upper part of the 

Austin transgresses to a higher position in the 

geologic column, so that in Fannin and IIunt 

counties the following succession of mappable 

units is recognizable: Woodbine sand, Eagle 

Ford clay, unnamed clays and sands beneath 

the Austin chalk, Ector tongue of Austin chalk, 

unnamed clay in the vicinity of Bonham, AnThe topmost division of the Denison forma- nona tongue of Austin chalk, Taylor marl 

tion and of the Washita group, known as the ·(includingWolfeCityandPecanGapmembers), 

Grayson marl, consists of 15 to 25 feet of light and Navarro formation. Still farther to the 

grf1enish-gray calcareous clay or marl with northeast, in Lamar, Delta, and I-Iopkins 

lmnps of white lime and several nodular thin counties, the succession of units is as follows: 

layers of limestone. The fossils carried by the Woodbine sand (exposed at Arthurs Bluff, on 

marl include species of Gryphaea, Pecten, Tri- Red River), Eagle Ford formation (largely 

9onia, Plicatula, Protocardia, Turrilites, and concealed by terrace deposits), unnamed sands 

1-Ioplites, of which Gryphaea mucronata Gabb is and clays (also largely. concealed), Blossom 

perhaps the most common. sand, Brownstown marl, Annona tongue of 

The marl is poorly exposed above the Main Austin chalk, Taylor marl, and Navarro formaStreet lim_estone about the headwater branches tion. The age relations of the units just 

of Pawpaw Creek, in the eastern part of Deni- named in different parts of the area are diason. The best exposure examined was in a pit grammatically represented in the correlation 

south of the Missouri, Oklahoma & Gulf Rail- section given in Plate XXX, 0 (p. 155). 

way about a quarter of a mile east of the sta- The Gulf series is referable in its entirety to 

tion at Denison, w_here a thickness of 16 feet of J the Upper Cretaceous, though, as indi?ated. on 

the marl was noted. page 134, it may not include representatives of 

Other exposures in Grayson County occur in the lowermost part of the Upper Cretaceous. 

the banks of headwater bran_ches of Iron Ore The nature of the contact separating the Gulf 

Creek near the Missouri, Kansas & Texas Rail- series from the underlying Comanche series 

way 5! to 5~ miles west of Denison;· in the has not been satisfactorily determined in northbank of a headwater branch of Little Mineral eastern Texas. Probably it is that of unconCreek near the crossing of the Henderson Ferry formity, the basal formation of the upper 

road, 2! miles north of Pottsboro and seven- series, the Woodbine sand, having been deposeighths of a mile south of Fink; and at intervals ited in the shal1ow waters of the transgressing 

on and near the public road leading west from sea, in the deeper waters of which the succeedFink for a distance of about 4 miles. ing truly marine sediments of the series were 

• 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 120 PLATE XXVI 

IN THE HILLY AREA U DERLAIN BY THE WOODBINE 

SOUTHWEST OF DE ISON, GHAYSON COUNTY, TEX. 

View looking northeast toward the old waterworks plant. 

B. A DETAIL OF TOPOGRAPHY IN A SMALL BRANCH VALLEY UNDERLAIN BY THE WOOD· 

BINE SAND 1)1 MILES SOUTHWEST OF DE !SON, GHAYSON COUNTY, TEX. 
U. S . GEOLOGICAL SURVEY PROFESSIONAL PAPER 120 PLATE XXVII 

A. CONTACT BETWEEN THE EAGLE FORD CLAY AND THE AUSTIN CHALK IN A QUARRY 

OF THE TEXAS PORTLAND CEMENT CO. 3 MILES WEST OF DALLAS, TEX. 

The contact between the Eagle Ford clay and the Austin chalk is approximately marked by the crest of the prominent 

bench in the foreground. 

B . "FISH-BED CONGLOMERATE" mIN TilE BED OF A BRA CH 3 MILES SOUTH OF RAVEN A, 

FANNI COU TY, TEX. 

The indurated conglomeratic layer is immediat.ely underlain by somewhat argillaceous fine marine sand, which here 

forms the topmost stratum of the Eagle Ford clay. 
GEOLOGY OF NORTHEASTER.N TEXAS AND SOUTHERN OKLAHOMA. 145 

laid down. Toward the south the Woodbine stone, and argillaceous shelly sandstone which 

sand hecon1es progressively thinner, finally contains large lenslike calcareous concretions 

disappearing in :McLennan County, south of and laminated argillaceous sandstones at the 

which the Eagle Ford clay rests directly upon top." Sand seems to predominate over clay, 

the Bucla limestone. of the Comanche series. producing a pronounced sand-hill type of 

The absence of the Woodbine in central and .topography, as in the country immecliat.ely 

southwestern Texas would therefore seem to southwest and west of Denison; but locally 

indicate unconformity, unless the age equiva- clay makes up the bulk of the formation, 

lent of the '\iVoodbine lies in the relatively thin producing a smoothly rolling surface, as in the 

sediments that compose the Bbda limestone, a belt of country northwest of Pottsboro. (See 

supposition which seems highly improbable, p. 132.) 

and which has no basis of known fact. Fossil leaves have been obtained from the 

wooDBINE s:\.ND. lower n1en1ber (Hill's J?exter sands) of the 

' Woodbine near Denison. The upper member 

The Woodbine sand, named from the village (I-Iill's Lewisville beds) yields a peculiar shalof vVooclbine, in Cooke County, is the basal l 

ow n1arine fauna that differs rnarkeclly fron1 division of the Gulf series in northeastern the Cretaceous faunas either below or above it 

Texas. It is a highly variable formation, con- in Texas. This fauna is best known from 

sisting of strongly current-bedded, more or less 

exposures on Tirnber Creek, 3 or 4 rniles west, 

ferruginous sand and laminated shaly clay, southwest, and south of Lewisville, Denton 

with some interbedded layers of lignite ar1d County, Tex., and though it includes a relalignitic clay. On account of the irregularity tively small nun1ber of species is rich in incliof the bedding it is scn,rcely possib1e to determine 

the thickness of tho formation from surface viclua.ls, which largely make up certain lenses 

and layers of the formation. The following are 

son1e of the species that have been described: 

Area (Barbatia) micronema (:~•Ieek), numerous. 

Ostrea soleniscus Meek, very numerous. 

Modiolus filisculptus Cragin. 

Cytherea leveretti Cra3'in. 

Cerithium tramatensis Cragin. 

Cerithium intcrlineatum Cragin 

outcrops, hut it is rettsonably certain that in 

Grayson County the thickness is not less than 

300 or 400 feet and nHty be as great as 500 feet. 

A well at Ladonia, in the southeast corner of 

Fannin County, penetrated between depths of 

1,800 and 2,425 feet about 62.5 feet of sand and 

clay which are interpreted as belonging to the 

Woodbine. As stated above, the Woodbine 

becomes progressively thinner toward the The fossiliferous strata of the upper member 

south, finally disappearing in :McLennan County. are represented in Grayson Cotmty, though 

The fornuttion is traceable eastward frmn Gru,y- they are not so conspicuously exposed as they 

son County through Texas and into Arkansas, are on Tin1ber Creek iu Denton County. 

where it is believed to be represented by a part Fossil plants have also been collected from 

at least of the Bingen sand. beds regarded as representing the Woodbine 

The scope of this paper will not permit a ·formation at Arthurs Bluff, on Reel River 15 

detailed account of the many different litho- miles north of Paris, in Lamar County, Tex. 

logic ~tspects of the formation, for which the The· Woodbine sand outcrops in a belt a few 

reader is referred to the sections described by Hill miles wide along the south limb of the Preston 

and Taff in the papers listed on pages 130-131. anticline (see geologic rnap, Pl. XVII) and in a 

Hill recognized t\vo subdivisions of the Wood- north-south belt along the western border of the 

bine-a lower member, called by him the Dex- area. mapped. The belt of outcrop wraps 

ter sands, consisting of an estimated thickness around the southeastward-plunging nose of the 

of 160 feet df "brown and yellow ferruginous Preston anticline in northwestern Fannin 

sandstone heavily laden with siliceous iron- County, Tex., and passes northward into Oklastone," and an upper member, called by him homa, where it extends in a broad belt to the 

the Lewisville beds, consisting of 150 feet or northwest and north, and to the east q.own the 

more of "laminated 1ignitic sands and sandy Red River valley. Exposures of the Woodbine 

clays, interstratified with brown sands, fer- at three localities are shown in Plates XXIV, .A, 

ruginous reddish-brown sandstone, shell sand- and XXV, A and B. 
146 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

The formation may be studied to advantage 

on sandy hills along the northern margin ·of the 

belt of outcrop between Pottsboro and Cedar 

Mills, in Grayson County; in road and railroad 

cuts and creek beds between Denison and 

Pottsboro, and for several miles southwest of 

Denison; in cuts of the Missouri, Kansas &. 

Texas Railway in the western outskirts of Denison, Grayson County (see Pl. XXIV, A); inroads 

and stream banks and beds in the hilly country 

within 6 or 7 miles east-southeast of Denison; 

on sandy hills · in the northwestern part of 

Fannin County; and .at Hyatts Bluff, on Red 

River just above the mouth of Caney Creek, 6 

miles northwest of Ravenna, Fannin County 

(Pl. XXV, A). 

Hyatts Bluff, not heretofore described, is 

half a mile long and 45 feet high and trends 

N. 28° E. Reddish terrace sand forms the 

upper 20 feet of the section, beneath which are 

25 feet of Woodbine strata consisting of soft 

cross-bedded glauconitic sandstone; darkgreenish, more massive soft glauconitic sandstone; small lenses of pebbly sand; and dark 

shaly clay. ·The n1ain bedding planes are 

fairly persistent and dip perceptibly downstream. One persistent sandstone stratum 

2! feet thick, overlain by a lignitic band a foot 

thick, was traced from a point where it is 20 

feet above water lev~l'for 1,800 feet along the 

face of the bluff· to a point where it passes beneath water level. The dark shaly clay forming the portion of the section that is stratigraphically highest in the Woodbine contains 

concretions of iron car]:>Onate, some of which 

are fossiliferous, and there is one layer of darkgreenish glauconitic soft sandstone containing 

the abundant remains of a poorly preserved 

molluscan fauna that inhabited a shallow sea. 

The photograph reproduced in Plate XXV, A, 

was taken where the lignitic band lies at water 

level and is overlain by 4 or 5 feet of shaly, 

easily eroded clay. The conspicuous projecting ledge is highly cross-bedded sandstone along 

the base of which are discontinuous small lenses 

of conglomerate. 

EAGLE FORD CLAY. 

The Woodbine sand is overlain· by the Eagle 

Ford clay,~ formation named from Eagle Ford, 

a village · 6 miles west of Dallas, where it is 

typically exposed. The formation · consists 

chiefly of dark bluish-gray to nearly black 

shaly clay which is as a rule gypsiferous and 

more or less bituminous; in places crystals of 

selenite weather from the clay in great numbers. In Grayson and Fannin counties the 

formation has an estimated thickness bet,,reen 

300 and 400 feet. Thin, platy layers of sandstone and sandy limestone, some bearing the 

imprints of small costate and keeled ammonites, occur in the formation, particularly 

in the central· portion. Flattish calcareous 

nodules occur .in the lower part of the formation, and oval to spherical hard limestone septaria are chara~teristic of the upper part. In 

the upper 20 or '25 feet of the formation in the 

vicinity of Sherman the dark clays are. interstratified with beds of sand, one of which, 15 

to 20 feet below the base of the Austin chalk, 

carries vast numbers of the small fluted oyster, 

Ostrea lugubris Conrad. Ten feet below the 

base of the ·Austin chalk, which in Grayson 

County overlies the Eagle Ford, is a conglomeratic layer of .gray sandstone, carrying numerous more or less rounded phosphatic pebbles, 

shells of Ostrea alifera Cragin, and fish . teeth, 

of which shark teeth are common. This is the 

"fish-bed conglomerate" of Taff, 1 which in 

the opinion of the present writer (see p. 149) 

should not be included in the Eagle Ford but 

should be regarded as the base of the sediments that have their typical expression in the 

Austin chalk. 

The form'ation outcrops in an east-west belt, 

through the northern part of Grayson County 

and the northwestern part of Fannin County, 

but the belt is sharply deflected to the south in 

northwestern Fannin County, where it passes 

around the southeast end of the Preston anticline. In the northern part of Fannin County 

the formation passes under the Pleistocene 

terrace deposits of the Red River valley; east 

of Fannin County the only place where it has 

been certainly recognized in surface. outcrops 

is ~arretts Bluff, in the northwestern part of 

Lamar County. Two localities where the formation can be advantageously studied in 

northern Fannin County are at Sowells Bluff, 

on Red River 5 miles northwest of Ivanhoe, 

and in deep ravines in the we~tward-facing 

slope of theRed River valley 6 miles north of 

Ivanhoe. At the last-named locality, where 

approximately 140 feet of strata are exposed, 

the upper part of the section exhibits a larger 

lTexas Geol. Survey Fourth Ann. Rept., for 1892, pp. 299-304, 1893. 
0 

GEOLOGY OF NORTHEASTERN TEXAS AND SOUTHER.N OKLAHOMA. 147 

proportion of sandstone than is typical of the slope of the Mill Creek valley 2 miles in an air 

formution, and some beds of. the sand~t.one are line southwest of Bells, where it is underlain 

cross-bedded, simulating the Woodbine sand. by 15 or 20 feet of fine gray massive marine 

Below this dominantly sandy portion, 40 or 50 sand. The base of the Austin chalk appears 

feet below the top of -the section, is a gravel at a higher Jevel in the same road a short dislayer generally less than a foot thick, composed tance east of the outcropping ledge of sandchiefly of dark, smooth pebbles which have not stone, from which it is separated by 10 or 15 

yet been critically studied. This may repre- feet of poorly exposed strata, apparently clay. 

sent the "fish-bed conglomerate," in which From the vicinity of Bells eastward these 

case both the pebble layer and the beds above upper sandy beds of the Eagle Ford have proit, including the dominantly sandy strata, .duced a narrow belt of country characterized 

should, in the writer's opinion, be excluded by sandy soil and rougher topography than 

from the Eagle Ford formation. Character- that exhibited by the adjacent land either to 

istic Eagle Ford fossils have been obtained the north or to the south. Outcrops of the perfrom wells in northeastern Louisiana. 1 sistent "fish-bed conglomerate" occur here and 

West of Sherman and Denison the belt of there just above the sand and serve as a check 

outcrop bends nearly due south and is traceable to the correlation of this sandy member of the 

through Texas to the Rio Grande, which it Eagle Ford, which crosses the headwaters of 

intercepts in Kinney and Val verde COU:Jl ties. Caney Creek 2! miles sou the as t of Bells and, a pW ell records show the formation to be 535 feet proximately paralleling this creek, swings 

thick in the western part of Collin County, around the plunging nose of the Preston antiTex., and 460 to "485 feet in the vicinity of cline and extends to the northeast past Lesleys 

Dallas; south of Dallas it becon1es thinner, schoolhouse, Ector, and Ravenna, in Fannin 

reaching a minimum of about 30 feet at Austin; County. The "fish-bed conglomerate" is more 

southwestward and westward from Austin the fully described on pages 148-149. 

thickness again increases, being 75 feet or more The upper part of the Eagle Ford formation 

in the Uvalde quadrangle and about 250 feet in is exposed in a branch west of a north-south 

the Brackett quadrangle. road and south of an east-west portion of the 

The sandy beds at the top of the Eagle Ford same road 3 miles south of Ravenna. !romehave been traced from the vicinity of Sherman diately below the conglomerate at the locality 

eastward through Grayson County and north- shown in Plate XXVII, B, is 5 feet of fine 

eastward to about the north-central part of argillaceous marine sand, near the top of 

Fannin County. Good exposures of the sandy which was observed a large piece of lignite. 

beds occur in the vicinity of Bells in eastern Within about a quarter of a mile farther down 

Grayson County. A mile west of Bells the the brancl;J. occur good exposures of typical 

east-west public road that runs about a quarter dark sh~ly gypsiferous clay of the Eagle Ford 

of a mile south of the Texas & Pacific Railway formation; interbedded with this clay are 

·crosses a layer of ferruginous sandstone at the subordinate layers of fine-grained sandstone 

head of a northward-flowing branch of Mill and a few layers and lenses of gray calcareous 

Creek, which probably represents the "fish-bed earthy rock that exhibits finely developed 

conglomerate." (Seep. 146.) The sandstone cone-in-cone structure. In places thick layers 

is underlain by 4 or 5 feet of dark greenish-gray of this earthy rock surround apparently conmassive sand, and in succession down the cretionary masses of limestone. Several speciravine follow 35 or 40 feet of more or less argil- mens of Ostrea lugubris Conrad.were f()und loose 

laceous fine sand, with layers of soft yellow in. the bed of the _9reek below the outcrop of the 

sandstone at intervals, and about. 40 feet of conglomerate and probably ·came from some 

dark shaly gypsiferous septaria-bearing clay, bed in the upper part of the Eagle Ford. 

typical of the Eagle Ford clay. Some of the common fossils of use in recogAnother good exposure of the sandstone nizing the Eagle Ford formation are Ostrea 

· layer ("fish-bed conglomerate") occurs in an lugubris Conrad, 0 .. al?fera Cragin, fish. teeth 

east-west public road on the westward-facing belonging to the species Ptychodus whipplei 

. Marcou, Inoceramus labiatus Schlotheim, I. I Matson, G. c., The DeSoto-Red River oll and gas field, La.: U.S. fi ·z· H ll d M k d ll k 1 d 

oeol. survey Bull. 661, p. us, 1917. rag~ ~.s a an ee , an sma · ee e arnmo-
148 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

nites belonging to· Prionotropis or Prionocyclus, 

or to both. Of these the first three occur only 

in the upper 40 or 50 feet of the formation. 

A US TIN CHALK. 

T.YPICAL AREA. 

The Austin chalk is typically exposed in the 

vicinity of Austin, Travis County, Tex., where 

it rests upon the Eagle Ford clay, is approximately 410 feet thick, and consists of white 

chalky limestone in beds of varying thickness, 

with interbedded marly layers in its upper twofifths. Some of the common fossils that are 

especially ch~racteristic of the formation are 

the following: 

Inoceramus undulato-plicatus Roemer. 

Ostrea a.ff. 0. diluviana Lamarck (uppermost part). 

Grypha:a aucella Roemer. 

Exogyra ponderosa Roemer (upper half). 

Exogyra laeviuscula Roemer (upper half). 

Racliolites austinensis Roemer. 

Mortoniceras texanus CR()emer). 

The Austin chalk extends from the Rio 

Grande in Maverick County, Tex., eastward by 

way of Uvalde to San Antonio, thence northeastward to Austin, and thence northward by 

way of Waco and Austin to- Grayson County. 

From Austin northward the chalk thickens, 

and its upper surface appears gradually to 

transgress upward across the geologic column, 

or, in other words, to become younger, until 

in the latitude of Sherman the uppern1ost bed 

of chalk is considerably younger than the top 

of the chalk at Austin and occupies a position 

stratigraphically 400 or 500 feet higher. The 

exact manner in which this upward transgression takes place, whether by a gradual rise or by 

minor tongues of chalk at successively higher 

positions, has not been determined, very little 

detailed field work having been done in the 

intervening area. 

DEVELOPMENT IN NORTHEASTERN TEXAS. 

SALIENT FEATURES. \, 

In the Sherman-Greenville section the Austin chalk is probably not less than 1,000 feet 

thick. In the eastern part of Grayson County 

and the western part of Fannin County, however, the lower two-fifths or more of the chalk 

becomes impure and gradually passes laterally 

into nonchalky sands and clays and only 

slightly chalky clay marls. In a section drawn 

through Bonham, Fannin County, and Commerce, Hunt County, the succession of recog ... 

nizable and mappable lithologic units is decidedly different from that in the latitude of 

Austin. In Collin, Hunt, and Delta counties 

other lithologic changes have taken place in 

beds above the chalk, representing the upper 

part of the Taylor marl, and these changes add 

further contrast to the section. in northeastern 

Texas as compared to that in the Austin region. 

These relations are diagrammatically shown in 

Plate XL~, 0. . 

In the Bonham-Comn1erce section the following divisions, named in ascending order, together represent the chalk and its equivalents 

in this area: A band of basal non chalky clay 

and sand 10 to 35 feet thick, with the "fishbed conglomerate" described below, at its base,· 

all mapped with the Ector tongue; the Ector 

tongue of the Austin chalk; an unnan1ed transitional clay in the vicinity of Bonham (p.150); 

and the Annona tongue of the Austin chalk. 

(See Pl. XXX, 0.) 

In the longitude of Paris, Lamar County, the 

chalk and its equivalents include imperfectly 

known beds, probably clay, sand, and marl, 

representing the eastward extension of the 

Ector tongue and part of the clay in. the vicinity of Bonham; the Blossom sand; the Brownstown marl; and the Annona tongue of the Austin chalk. (See Pl. XXX, 0.) 

UNNAMED CLAYS AND SANDS CONTEMPORANEOUS WITH 

BASAL PART OF TYPICAL AUSTIN CHALK. 

Phosphatic pebbles occur in the base of the 

Austin chalk, immediately above its contact 

with the underlying Eagle Ford formation, in 

a quarry of the Texas Portland Cement Co., 

3 miles west of Dallas, Tex. (See Pl. XXVII, 

A.) In Grayson County, Tex., a conglomeratic layer, a few inches to 30 inches thick, 

called by Taff 1 the "fish-bed conglomerate," 

occurs 10 feet below the base of the chalk, with 

beds of shaly clay and sand intervening. From 

Grayson County the conglomerate extends eastward into Fannin County, where from west to 

east the interval between the conglomerate and 

the base of the overlying chalk, which is here 

the Ector tongue of the Austin, gradually increases until in the vicinity of Ector and R avenna it is not less than 35 feet. Between 

Ector and Ravenna, in Fannin County, the 

material in this interval is n1ostly greenish cal1 Texas Geol. Survey Fourth Ann. Rept., pp. 303, 304, 1~93. 

0 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 120 PLATE XXVIII 

A . ANNO A TONGUE OF AUSTIN CHALK IN THE BANK OF A CREEK 5~-2 MILES WEST OF 

LEONARD, FANNIN COUNTY, TEX. 

The beds, which dip perceptibly downstream, comprise massive layers of chalk interbedded with shaly layers 6 

inches to 2 feet thick. 

B. BUILDING-STONE FACIES AT TOP OF ANNONA TONGUE OF• AUSTIN CHALK IN AN ABANDONED QUARRY 3 MILES SOUTH OF HONEY GROVE, FANNIN COUNTY, TEX. 
GEOLOGY OF NORTHEASTERN TEXAS AND SOUTHERN OKLAHOMA. 149 

careous shaly clay becoming n1ore or less sandy, be explained as having been mechanically introwith lenses of sand and sandstone in the lower duced from underlying Eagle Ford strata in 0 10 fee11. Li1jhologically the clay is of lighter place. 

color than the typical clay of the Eagle Ford. ECTOR TONGuE. 

The "fish-qed conglomerate" is well exposed 

in a branch west of a north-south public road The Ector tongue of the Austin chalk, a thin 

3 n1iles south of Ravenna, where it forms a tonguelike projection of chalk frorrt the basal 

ledge across the bed of the stream. (See Pl. beds of ·the 1nain body of the Austin, has been 

XXVII, B.) At this place it consists of a con- traced, by means of a few outcrops and the 

glomeratic layer about 10 inches thick com- black soils to which the chalk weathers, from 

posed of coarse calcareous sand, grayish and western Fannin County northeastward to a 

brownish phosphatic pebbles, a few pebbles point about a mile and a half southeast of 

of quartz and chert, and scattered shark teeth. Ravenna. (See Pl. XVII.) Ector, frmn which 

One specimen of Ostrea alijera Cragin was ob- the tongue is na1ned, is a few hundred yards 

tained from the conglomerate at another out- west of the belt of outcrop, which is rather 

crop in an east-west road about a quarter of a strongly deflected where it passes around the 

mile northwest of this locality, where also a southeastern nose of the Preston anticline. 

thin interbedded · layer of earthy limestone Only 10 or 15 feet of the chalk was seen in the 

exhibiting cone-in-cone structure was noted. best exposures, and it probably does not exOne pebble fron1 the conglon1erate was exam- ceed 50 feet in thickness in the vicinity of 

ined qualitatively by W. B. Hicks in ·the Ector. The Ector tongue is underlain by shaly 

chemical laboratory of the United States Geo- clay, which apparently grades it~to the chalk 

logical Survey and found to be composed chiefly through a thickness of only a foot or two of 

of calcium phosphate. The conglomerate is n1aterial. This clay, together with thin beds 

here about 35 feet below the base of the Ector of sand and a basal conglmnerat3 ("fish-bed 

tongue of the Austin chalk (see Pl. XXX, 0)~ conglomerate") associated with it,. are re·· 

and apparently the intervening strata are· garded as distinct fron1 the Eagle Ford forma·· 

chiefly greenish shaly clay. tion and as mote closely related in origin to the 

A gravel bed that 1nay represent the north- overlying Austin chalk and its equivalents. 

eastward continuation from the preceding (See above.) These basal beds are. 1napped 

locality of the "fish-bed conglon1erate" is de- with the Austin chalk and its extension, the 

scribed on pages 146-147. · Ector tongue. No exposures of the Ector 

The significance of the "fish-bed conglom- tongue showing clearly its relation' to the clay 

erato" in the geologic history of this part of of Austin age that O>verlies it we're seen. 

Texas has not been definitely determined. The. chalk is poorly exposed in the public 

:Heretofore the conglon1erate, together with road north of the Texas & Pacific Railway 

the 10 to 35 feet of clay and sand that intervene about a quarter of a mile east of Ector. 

between it and the overlying chalk, have been Another exposure appears in an east-west 

regarded as forming the uppermost part of the public road about 3 miles north by east of 

Eagle Ford. The conglmnerate, lying in1me- Ector, or 5t miles northwest of Bonham; here 

diately ttbove sn,ndy beds that are obviously of several feet of the chalk is underlain by clay, 

shallow-water n1arine origin, strongly suggests the passage fr01n the clay to the chalk appara tmnporary uplift of the sea bottom of this area ently being transitional through a thickness of 

above sea level, followed soon after by a read- a foot or more of material. 

vance of thE sea and the formation of the pebble In other exposures revealed by a small branch 

bed as a basal conglmnerate n1arking the begin- and gullies west of a north-south public road 

ning of the cycle of deposition that has its typi- 3 miles south of Ravenna the weathered rock 

cal expression in the Austin chalk. This inter- has the appearance of typical chalk of the 

pretation, ~f found to be correct, would seem Austin and yielded the characteristic fossils 

to necessitate the exclusion of the conglom- Gryphaea aucella Roemer and Radiolites auserate and the overlying clay and sand from tinensis Roemer. As noted above, the "fishthe Eagle Forcl. Such Eagle Ford fossils as bed conglomerate" crops out in the bed of 

the conglon1erate may be found to contain can the branch and in an east-west public road less 

• 
' 

150 . SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, l!HS. 

than a quarter of a mile west of this locality, 

in a position about 35 feet stratigraphically 

lower than the base of the chalk. 

The belt of chalk of the Ector tongue crosses 

the old Bonham-Ravenna road about 1! miles 

southeast of Ravenna, where the chalk was 

seen in a small, poor exposure in the road ditch. 

This is the easternmost locality at which this 

chalk has been recognized, and its identification farther east would· probably be accomplished with difficulty, owing to the extensive 

covering of Pleistocene alluvial deposits in a 

broad belt south of Red River in Fannin and 

Lamar counties. It is assumed for the present 

that the chalk loses its identity toward the east 

by merging into contemporaneous nonchalky 

clays or sands. 

The structure contours in the vicinity of 

Savoy, Ector, and Ravenna shown in Plate 

XVII indicate the altitude above sea level of 

the base of the Ector tongue. 

TRANSITIONAL CJ,AYS NEAR BONHAM. 

and Ostrea plumosa Morton. These fossils, 

though in themselves not conclusive evidence, 

combined with the lithologic evidence mentioned above indicate that the glauconitic clay 

represents the Blossom sand. A layer of impure sandy limestone exposed in a small 

branch at the crossing of the road to Prospect 

Church, 3 miles northwest of Dodd City, Fannin County, yielded Aguilaria?, lnocera.mus 

sp., · Ostrea plurnosa 'Morton, Gryphaea aucella 

Roemer, Baculites asper Morton, and Prionotropis?. These fossils indicate that this locality also lies within the belt of clay representing 

the Blossom sand. 

The upper part of the clay in the vicinity of 

Bonham above the glauconitic band is greenish and waxy and contains a few calcareous 

septaria; it represents the Brownstown marl, 

which, in the vicinity of Paris, lies above the 

Blo~som sand and below the Annona tongue of 

the Austin chalk. (See Pl. XXX, 0.) 

In Plate XXX, 0, the clay in the vicinity of 

Bonham is represented as merging toward the 

The Ector tongue of the Austin chalk is over- west through calcareous clay into the Austin 

lain in the west-central part of Fannin County chalk. That this interpretation is correct, ' 

by greenish-gray waxy clay, weathering yel- and that the merging takes place gradually 

lowish green, which in the Bonham region through a considerable linear distance, apappears to occupy the entir~ interval of approx- pears to be confirmed by all the observations 

imately 400 feet above the Ector tongu.e and that have been made in the area. On the 

below the Annona tongue of the Austin. Ex- strike of the clay in the area between Bells 

posures of the clay appear in roads and streets and Whitewright, in eastern Grayson County, 

both north and south of Bonham and in the the rock underlying the surface is con1posed 

ditches of the roads leading to the north, north- largely of impure argillaceous chalk and chalky 

west, west, and southwest. As considerable clay that appear to be transitional, and even as 

areas bordering Bois d'Arc Creek are covered far west as the vicinity of Luella, in the eastby terrace clay derived chiefly from the under- central part of Grayson County, a considerable 

lyjng Cretaceous clay, it is in places difficult to thickness of the Austin is a highly argillaceous, 

determine whether the more or less weathered slightly bituminous shaly chalk or chalky clay. 

materials are residual from the undisturbed This facies of the Austin is exposed in gullies 

older clay or from the reworked terrace deposits. in the small branches of Cedar Creek· near 

A little above the middle of this body of clay I Luella and in the northward-flowing b~anches 

is a band of glauconitic clay, of undetermined 1 and northward-facing slopes of Choctaw Creek 

thickness, that is lithologically identical with north of Luella. · 

pockets or lenses of ·glauconitic clay in the ·The lower part of the clay in the vicinity of 

Blossom sand near Paris, Lamar County. This Bonham has not been traced farther east than 

band has been recognized in poor exposures in the central part of Fannin County, beyond 

street ditches south of the railroad in Bonham, which in northeastern Fannin and northern 

and in somewhat better exposures on the Ran- Lamar counties the strata are largely obscured 

dolph road 5 and 6! miles by the road south- by an extensive covering of Pleistocene alluwest of Bonham. At the last-mentioned local- vial 'terrace deposits and are therefore imperity the clay is calcareous and strongly glau- fectly known. :However, the distribution and 

conitic and contains fragments of a large relations of the clay seem to indicate that 

species of· inoceramus, Ostrea congesta ·conrad, either it or equivalent material that is. litho-

• 
GEOLOGY OF NORTHEASTERN TEXAS AND SOUTHERN OKLAHOMA. 151 

logically different, such as sand or marl, 

tends eastwn.rd stratigraphically beneath 

Blosso1n sand. (See Pl. XXX, 0.) 

ex-~ still farther east higher beds successively become chalky 

the marl, so that within a comparatively short distance only 

the upper part of the chalk formation as it occurs farther 

south is true chalk. In other . words, the white chalk 

ANNONA TONGUE. transgresses upward in the series of Cretaceous rocks from 

The division to which the n::tme Annon,a is the vicinity of Sherman, Tex., eastward into Arka~sas. 

now applied was originally called the "White It is not quite clear from this quotation 

Cliffs chalk" by Hill/ from White Cliffs village whether Taff regarded the Annona as actual.ly 

and bluff, on Little River, Little River County, younger than the upper part of the type Austin, 

Ark. Because "vVhite Cliffs" was preoccu- · or whether the laf3t sentence of the quotation 

pied ;as a formation name, Hill, in 1901,2 re- refers only to an upward transgression of the 

nan1ed the chalk Annona,. from the town of base of the chalk. 

Annona, in Red River County, 'fex. The new Gordon 6 also recognized the continuity of 

nmne was inappropriate, for Annona is sev- the Austin and Annona but did not detect the 

eral milea south of the belt of outcrop of upward transgression of the top of the chalk 

the chalk, but the name has become so com- across the geologic column from Austin northmanly used that it should be retained, with the ward. He therefore combined the Annona 

understanding, however, that the chalk does chalk and underlying Brownstown marl under 

not outcrop at Annona-in fact, the section the name Austin group, which he represented 

at White Cliffs, AI~k., should continue to be as occupying the time interval of the typical 

regarded as the type locality of the division. Austin of central Texas. 

Hills regarded the Annona as stratigraph- The Annona tongue in northeastern Texas 

ically higher than the Austin as developed in consists of 400 or 450 feet of bluish-gray brittle, 

its type area, for he says: more or less argillaceous chalk, which breaks 

with a conchoidal fracture and weathers to 

white bald spots such as are typical of the area 

farther so·uth in Texas underlain by the 1nain 

body of the Austin chalk. · The chalk is sliO'htlv 

It is not known what has become of the Austin chalk in 

this section [Paris, Tex.], but my hypothesis, backed by 

some evidence, is that to the southward it has been faulted 

down. The Anona (White Cliffs) is an entirely distinct 

and higher bed. for it is underlain by the Taylor (Exogyru 

ponderosa) marls, which overlie the Austin chalk. 

In a later repo~t 2 he says:-

The chalky (Anona) beds (the White Cliffs chalk of the 

writer's Arkansas section) outcrop at Clarksville and thence 

via Paxton [Roxton] and Honey Grove nearly to Bonham 

but are not known south of thesf! points. The writer has 

considered this chalk· to represent a higher horizon than 

the Austin chalk, but its exact relationship is subject to 

future determination. 

Outcrops of chalk north of Windom and 

Honey Grove, in Fannin County, which in 

reality lie within the belt of outcrop of the Annona, were regarded by Hill • as belonging to 

the Austin. 

Taff 5 recognized tp.e geographic continuity of 

the Austin and Annona and also· the fact that 

the lower part of the Austin is represented ·in 

northeastern Texas by beds that are not typical 

0 ~ 

bituminous, fresh samples from practically any 

part of it having a decided bituminous odor 

when struck with the hammer and yielding 

small quantities of oil by destructive distillation. The Annona has been traced almost continuously from a point north of Annona, in 

Red River County, through Lamar and Fannin 

counties to the southwestern part of Fannin 

County, where it is found to be continuous with 

the upper part of the main body of the Austin 

chalk (see Pl. XVII and Pl. XXX, 0), and 

for that reason it is here regarded as a to.ngue 

of the Austin formation. No good exposure 

was found showing the relation of the Annona 

tongue to the underlying Brownstown marl, into 

which, however, the chalk probably merges 

through a vertical transition zone. 

The upper 5 to 10 feet of the Annona in parts 

of northeast Texas consists of soft, tough, 

The lowet· part of the thick chalk formation of north uniform chalk, which weathers to a soft cream 

Texas changes to marl in the vicinity of Sherman, and color and is capable of being readily sawed into 

chalk. IIe says: 

1 Arlmnsas Gcol. Sun·cy Ann. Rcpt. for 1888, vol. 2, pp. 87-89, 1R88 

»U. S. Gcol. Survey 'l'wcnty-flrst Ann. Rept., pt. 7, p, 341, 1901. • 

a Gcol. Soc. America Bull., vol. 5, p, 308, 1894. 

• U. S. Gcol. Survey 'l'wenty-first Ann. Rept., pt. 7, pl. 66, 1901. 

~ U. S. Gcol. Survey 'l'wenty-socond Ann. Rept., pt. 3, pp. 698-699, 

flg. 58, 1902. 

building blocks. It has been used locallv in 

the construction of foundations, chim~eys, 

dwellings, stores, churches, and courthouses. 

e Gordon, C. H., U. S. Geol. Survey Water-Supply Paper 276 ,pp. 

21-25, 1911. 
152 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

As a building stone, this rock appears to be BLOSSOM SAND. 

durable and is of pleasing appearance; in its 

toughness t1nd lack of brittleness the rock is in The sand to which the name Blossom is apstrong contrast to the chalk immediately under- plied was first recognized by Veatch 1 in wells 

lying it and to the ordinary chalks of the Cre- at ·Clarksville, Red River County, where it 

taceous formations of the Gulf Coastal Plain. con~titutes an important water-bearing forThe building-stone facies appears to be rather matwn; he called it the "sub-Clarksville sand.'' 

sharply separated from the overlying Taylor Gordon 2 renamed the sand the Blossom sand 

marl and forms a persistent stratum that has member of the Eagle Ford clay, correlating it 

been traced from a point south of Atlas, in . especially with the sandy beds that form the 

Lamar County, to Bailey, in Fannin County. upper part of the Eagle Ford in the vicinity of 

It was not seen in the vicinity of Leonard, Sherman, in Grayson County, an interpretaFannin County, but rock of apparently iden- tion which, as shown by the abundant evidence 

tical physical character crops out on the hills presented in this paper, is incorr~ct. 

4 miles east of :Mci{inney, in Collin County, The Blosson1 sand, which Gordon described 

where it has been quarried for building stone, as "brown sandy ferruginous glauconitic beds 

and similar rock has also been quarried about interlaminated with thin beds of clay, is over4 miles east of Allen, ColJin County. lain by the Brownstown marl and forms a belt 

About 13 miles east of Clarksville the ... t.\nnona of sandy country several miles wide extendpasses under the alluvium of Red River, ing westward through Red River County north 

beneath which it is concealed to the Arkansas of Clarksville; thence westward through Lamar 

boundary, but the chalk reappears at Rocky County, where Blossom and Paris are on the 

Comfort, in the southwestern part of Little outcrop; thence westward into Fannin County, 

River County, Ark., ~1nd again at White Cliffs, where north of Dodd City it merges into clay 

on Little River in the same county. It passes (see Pl. XXX, 0), chang1ng its topographic and 

as a narrow belt through the southeastern part much of its lithologic character. However, 

of I-Ioward County and thins and disappears in the clay into which it merges toward the west 

the western part of Hempstead County. retains its characteristic glauconitic content 

The set of structure contours on the O'eo- and is traceable psst the south side of Bonha1n 

logic map (Pl. XVII), extending from the :rea to a point about halfway between Ector and 

north of I-Ioney Grove southwest by west to Randolph. Some facies of the sand are strongly 

Randolph, Fannin .County, indicates the alti- calcareous and are chalky in appearance. 

tude above sea level.of the sloping base of the Fossil evidence indicates that the Blossom 

Annona tongue of the Austin chalk; the broad sand corresponds i~ age to the upper part, 

eastward deflection of these lines south of Bon- perhaps the upper half, of the Austin chalk as 

ham marks the eastward extension of the developed in the type area in Travis County. 

plunging nose of the Preston anticline. The The fossils listed in the table below have been 

set of contours extending from the area south collected at a sufficient number of localities 

of I-Ioney Grove, southwest by west past Gober between Blossom, in Lamar County, and a 

and Bailey_ to Leonard, Collin County, indi- point southwest of Bonham, in Fannin County, 

cates the altitude of the top of the Annona to amount to a virtual tracing of the beds 

tongue; the slight eastward deflection of these throughout this distance of about 50 miles. 

lines northeast of. Gober probably approxi- At least eleven of the speci~s are common to the 

mately marks the dying out of the uplift that A~stin chalk of the type area, whereas no Eagle 

produced the Preston anticline. The some- F.ord species appear in the list. Synchroneity 

what more pronounced southward deflection with the upper part of the type Austin is espeof these same contour lines at Leonard marks 

<tnother structural feature that is described on 

page 161 as _the Leonard-Celeste monoclinal 

fold. 

1 Veatch, A. C., Geology and. underground water resources of northern 

Louisiana and southern Arkansas: U. S. Geol. Survey Prof. Paper 46, 

p. 25, 1905. 2 Gordon, C. H., Geology and underground waters of northeastern 

Texas: U.S. Geol. Survey Water-Supply Paper 276, p. 19, 1911. 
GEOLOGY OF NORTHEASTERN TEXAS AND SOUTHERN OKLAHOMA. 153 

cially indicated by the following forms: Inoceramus aff. I. deformis Meek, Ostrea congesta 

Con1~ad, Ostrea aff. 0. diluviana Linne, Gryphaea 

aucella Roemer, Exogyra ponderosa Roemer, 

Liopistha elegantula (Roemer) ~ and Baculites 

asper :Morton. 

· 'rhe paleontologic evidence that the Blossoin sand is younger than the Eagle Ford ·is 

supplemented by the lithologic evidence, for 

hand specimens of glauconitic clay collected 

on the Randolph road 5 to 6! miles southwest 

of Bonham, Fannin County, in a bed that is 

stratigraphically well above the top of the· 

Eagle Ford, are identical in physical aspect 

with specimens from undoubted Blossom sand 

near Paris, Lamar County. 

Fossil speC'ies from the Blossom sand in .Fannin, Lamar, and Red River counties, Tex. 

Blossom sand. 

,..!..:S.i 

8s::::: ~~ p..l:: 

-;~ Oa. ~i~- p..~::S ~~~ ~t:l~ »oo p..'""::S 

Species. ~Jl s alQJ Q)rllo' §?SA !;-gj-i!:~ 

~l~ !;-alrll 

~ ..... 0 ~~~..., wS~ ~~~ ~-'0 r:n. o§ ~~a r:n. .0 r:FJ.""..., 

g~~ c;-;!;'5, g ·::-o8 ~ rll. gg. _P. -~~~-~ "b.o~ ~ '6JJ25'0 '6D8'0 ·61g'O b.Ou:> 

-a~tn.=: £S;.c £S;.c ~~~ ~,_ ~p.-

~§~ 0 ..., 

0-~ ~~ a>Q::S alQ::S. alQ Q) 

~:3g ~:§ g.c o.Qza ..., 'd .".:j g 

~~~~ ~~~~ r:FJ.O>, r:n,<:.>>. r:n. 0 >.~ 

-~.0 -~.0 -~.OP. 

0 0 0 0 0 

...!.cbQ 8 o...., -;::::~ <5.§~ 

~~gj 0~ Q) 0~:::: 

~...,-:5. >. ,.Q 

.... 

> ,c ~ >en._. ~~t: ::s~..., ~ ~g . r:n,al Qo .. r:n.r:..ooal ~j~Q -;.; •• t:l ~ ~~ ~ <:.>:>-

a ···a .. 5o;::::~ .S:?bgs 

i:>tt-:::l ·g,(5 0 -bi:~So ~O>·s .£S;,_ >. £0>,_ >. 0 'Q) g t:l.c·~ 

0.§~~~ os-8.15 0:3~~ oot>Q)a .~::J;:tl 

.~::~ ~~0'0 ~~6-o p 0 0 

Sandy lime- I Clay of ~ _ stone of Bios- o 

Bios- som ~ 

~~~ ago. .g 

...!..C 

8t: 

>.8it20 

Jj"Ej:g 

~c<:~o a .. A ..... ll:l~ 

g§~ 0 

o~t;.; 

a>Qa> 

O.Q ~ 

~~~ p 

..,!.~ 

g~ 

p..O 

a."' 

:--gj 

~== wSs 

-~·~ ~·r..c 

-61~§ .s:~!l:l 

oe>-

al~o O,Q..., 

cri~~ .~:: 

0 

:§ 

fj- <E 

Q)~ 

,.QQ) 

$~ 

I 

------------------1·------------------------

Vermes: 

Serpula sp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . X 

Mollusca: 

X X 

~~~~~~~~-~-~--·-:-c>Y\\/\ :y; ~u: Y\F~:: ~~}: ~l> ii~ii ;;~;; ~>~ :_-_-. i/-~~ Inoceramus aff. I. deformis Meek.... .. . . . . . . .. . . . . .. . . .. . .. . X . .. .. . . . .. .. X . . .. . . . .. .. . X 

~~~~~~~:~~~::~:~~~::::::::::::::::::: .. X .. :::::::::::::::::::::::: .. X .. ::.:::::::~::--~-- X X 

Ostrea congesta Conrad......... .. .. .. .. . . . . . .. .. . X X X X X X 

Ostrea plumosa Morton.......................... X X .. :. .. . .. .. . .. . . .. X X X 

Ostt·ea aff. 0. diluviana Linne................................ X . . . . . . . ..... . . .. . . . . . . . . .. .. .. X 

Gryphaea aucella Roemer.............................. . . . . . . X X X X X 

Exogyra ponderosa Roemer.......... . . . . . . . X X X X . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . X 

'frigonia SJ?. . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . X X ....................... . 

Pecten q mnq uecostatus Sower by... . . ... .. . . .. .. . . . .. .. . X X ... _ ._ ._ ._ ._ ... __ · ._ ._ ._ .. x_ .... _ ._ ._ ._ ._ .. : .. - _ ._._ .. I .. ~ .. Pecten sp .................................. : . . . . . . . . . . . . . . . . X 

Litna sp. . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . X X . . . . . . . . . . . . X ................. . Spondylus sp.. .... . .. ... .. .. . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . X ................. . Clavagella sp....................... .. . . . . . . . . . . . . . . . . . . . . . . X ................................... . Liopistha elegantula (Roemer)?...... . . . .. . . .. .. . . .. .. . X . .. . . . . .. .. . . .. . . . .. . . . . .. .. . . . .. .. . X 

Veniella sp......................... . . . . . . . . . . . . . . . . . . . . . . . . X ................................... . Cardium spillmani Conrad............ X ...... ,.. .. . . .. .. . . . . . . . . . ... .. . .. . . . .. .. . . . .. . .. . .... . X 

Cardium (Criocardium) sp............ X . .. .. . .. .. . . .. . . . . X ................................... . Cardiun1 sp......................... . . . . . . . . . . . . X X X X ....................... . Cycloristna sp....................... X ...................................................... · · · · · · Xenophora sp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . X X ....................... . Gyrodes sp.. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . X ................. . Volutoderma sp.... .... .. .. . . .. .. .. . . ... . . . ..... X X X X ................. . Anisotnyon sp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . X ................................•... Nautilus sp......................... . . . . . . . . . . . . . . . . . . X ......................................... . Harnites sp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . X X ................................... . Baculites asper Morton. . . . . . . . . . . . . . . . . . . . . . . . . . . ? X X ? X X X 

Placenticeras sp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . X ......................................... . Prionotropis? ......................................... ~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . X ........... . Vertebrata (fish): 

Corax falcatus Agassiz ................ 

1

...... . . . . . . . . . . . . X . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ? 

Otodus sp..................... .. . . . . . . . . . . . . . . . X .............................. 1 ................. . 
154 SHORTER CONTRIBUTIONS TO GENER_AL :GEO.LQGY., 1918. 

BROWNSTOWN MARL.. .'I'AYL0R MARL. 

The Brownstown marl in its type area in 'TYPICAL AREA. 

Arkansas 1 consists of about 600 feet ( ~) of blue The T~ylo~ marl is ~ypically developed in 

or gray calcareous clay or marl lying above the the vicinity of Tayl9r, Williamson County, 

Bingen sand and below the Annona tongue of and in Travis County, Tex., where it consists 

the Austin chalk. In northeastern Texas the of 540 feet or more of "bluish unctuous marly 

Brownstown overlies the Blossom sand and clay which wea,thers into yellow laminated 

underlies the Annona tongue, but its thiclaiess subsoil and black surface soil.'' 2 The formaprobably does not exceed 300 or 350 feet. In tion conformably overlies the Austin chalk 

Texas the marl resembles In a general way that. and is in. turn conformably overlain by the 

of the type area, though some of it consists of Navarro formation. The most common and 

gray waxy clay that is only slightly calcare- conspicu.ous fossil in the Taylor is Exogyra 

ous. Calcareous septaria have been observed ponderosa Roemer, which is particularly abunin the clay in places in Lamar and Fannin dant in the lower part of the. formation but 

counties. In general the soils produced by the which is also common in places 111 the upper 

Brownstown are of gray aspect and are in part of the formation. 

fairly strong contrast to the deep black soils of 

the Annona chalk on the south. The Brownstown marl extends westward, merging into the 

DEVELOPMENT IN NORTHEASTERN TEXAS. 

SALIENT FEATURES. 

upper part of the clay in the vicinity of Bon- The Taylor marl of northeastern Texas 

ham, Fannin County, and this clay in turn occupie~ the interval between the underlying 

merges toward the west into the Austin chalk, Annona tongue of the Austin chalk and the 

as described on page 150. overlying Navarro formation and has an 

The paleontologic character of the Browns- estimated thickness of 500 to 600 feet of strata. 

town marl has been only superficially studied. The correlation diagram (Pl. XXX, 0) shows 

Probably the most common fossil species other. that the Taylor of this area represents only 

than those of microscopic size is Exogyr~ pon- the upper part, perhaps not more than the 

derosa Roemer, which is very abundant in upper half, of the formation as developed in 

places in Texas and Arkansas. The following its type area in Williamson and Travis coun3pecies have been recognized in the formation ties. This difference in the time limits of the 

in Arkansas: formation is due to the upward transgression 

Hamulus major Gabb. of the top of the Austin from Travis County 

Hamulus onyx Morton. northward. Approximately the lower 475 feet 

Ostrea plumos1 Morton. of the Taylor as developed in Fannin and Hunt 

Exogyra ponderosa Ro.emer. counties consists mainly of gray or bluish-gray Anomia argentaria Morton. 

Paranomia scabra (Morton). calcareous shaly clay or marl, some portions of 

Liopistha (Cymella) bella (Conrad)? which are finely sandy; these deposits are of 

Crassatellites conradi (Whitfield)? similar lithologic character to the typical 

Cyprimeria depnissa (Conrad). Taylor marl of central Texas. 

Corbula crassiplica Gabb. The basal part of the Marlbrook marl of 

Turritella quadrilira Johnson. southwestern Arkansas, which rests upon the Haculites asper Morton. 

Annona chalk and contains Exogyra ponderosa 

When the Upper Cretaceous section of Roemer, probably corresponds to at least a 

northeastern Texas is compared with that of part of the Taylor marl of northeastern Texas. 

Colorado River in Travis County near Austin The upper part of the Marlbrook, which carries 

it appears that the Brownstown marl is the Exogyra cancellata Stephenson, though perequivalent in age of the lower part of the haps continuous with the Taylor, is younger 

faylor marl. This relation is indicated by than the Taylor and corresponds ih age with 

red line c in Pia te XXX, 0. 

1 U.s. Geol. Survey Prof. Paper 46, p. 25, 1906. 

2 U. 8. Geol. Survey Geol. Atlas, Austin folio (No. 76), columnar 

section 1, 1902. 
• 

U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 120 PLATE XXIX 

A. BASAL BEDS OF TITE PECAN GAP CHALK IN A CUT OF THE GULF, COLORADO & SANTA FE 

RAILWAY HALF A MILE EAST OF THE STATION AT PECAN GAP, DELTA COUNTY, TEX. 

B. FOSSILIFEROUS CONCRETIONARY LAYERS OF CALCAREOUS SANDSTONE IN THE WOLFE 

CITY SAND IN A CUT OF THE GULF, COLORADO & SANTA FE RAILWAY 1)1 MILES EAST 

BY NORTH OF WOLFE CITY, HUNT COUNTY, TEX. 
• 

U. S. GEOLOGICAL SURVEY 

.Exogyraponderosa- zone 

SW. 

"' 50 0 

' 0 

50 o' 

1,0 oO1,5 oo' 

2,0 oO2,5 0 

s. 

Base of Austin chalk 

I J 

A. STRUCTURE SECTION (A-A, PL. XVll ) ACROSS THE PRESTON ANTICLINE FROM A POINT 3 MILES WEST OF THE NORTHEAST CORNER OF THE 

DENISON QUADRANGLE, BRYAN COUNTY, OKLA., VIA WOODVILLE, FINK, AND POTTSBORO, TO SHERMAN, GRAYSON COUNTY, TEX. 

I .I 

of Annona ton~ue of Top Austin chalk 

Sea-Zeve~ 

ToP of woodbine Sand 

Estimated top of Comanche 

series 

Estimated to of Good land limestone 

. 

B. STRUCTURE SECTION (B-B, PL. XVII ) ACROSS THE LEONARD-CELESTE MONOCLINAL NOSE FROM LADONIA, FANNIN COUNTY, VIA WOLFE CITY 

AND CELESTE, HUNT COUNTY, TO A POINT 2 MILES WEST BY NORTH OF FARMERSVILLE, COLLIN COUNTY, TEX . 

PROFESSIONAL PAPER 120 PLATE XXX 

N. 

soc' 

NE . 

H 

soo' 

Sea-leveL o' 

soc' 

I ,ooo' 

I ,soc' 

2,000' 

2,5001 

C. GENERALIZED DIAGRAMMATIC SECTION SHOWING THE PHYSICAL AND AGE RELATIONS OF THE FORMATIONS OF THE GULF SERIES IN NORTHEASTERN AND CENTRAL TEXAS 

The red lines a, b, c, d, and e connect beds of equal age. The formations are all more or less variable in composition both horizontally and vertically, 

and the symbols represent only the dominant lithologic character Structural deformations are disregarded 

lCEi~~o====~~=i====i===~4C===~5~==~6====~7====8~===9E=== 10Nliles 
GEOLOGY OF NORTHEASTERN TEXAS AND SOUTHERN OKLAHOMA. 155 

the base of the Navarro-that is, with the 

beds containing Exogyra cancellata-that lie 

above the Pecan Gap chalk member of the 

Taylor. This age relation is explained by an 

assmned transgression of the Taylor marl 

upward in the geologic column from Hunt and 

Fannin counties, Tex., eastward toward Arkansas. 

The clay is overlain by the Wolfe City sand 

me1nber, described in greater detail below, 

and this in turn is followed by the Pecan Gap 

chalk member of the Taylor, also described 

below, the estimated thickness of which is 

between 25 and 50 feet. 

WOLFE CITY SAND MEMBER. 

Among the fossils recognized in the indurated layer in the preceding section were the 

foll.owing: 

Inoceramus sp. 

Pecten sp. 

Liopistha (Cymella) bella (Conrad). 

Cardium (Criocardium) sp. 

Leptosolen biplicatus Conrad. 

Corbula crassiplica Gabb. 

Cymbophora sp. 

Panope sp. 

Gastrochaena sp. 

Turritella trilira Conrad. 

Anchurn.? 

Pugnellus sp. 

Morea sp. 

Schizobasis sp. 

Baculites asper Morton. 

The Wolfe City sand member of the Taylor Scaphites (two or more species). 

marl consists of 75 to 100 feet of fine cal- The sand and characteristic included concareous gray sand or sandy marl with a few cretions are exposed in shallow cuts of the railround, oval, or irregular concretions of cal- road for the next 2 or 3 miles to the east. 

cureous sandstone. The sand weathers to Good exposures of the sand occur in ditches 

greenish yellow. Near the middle of the paralleling the Gulf, Colorado & Santa Fe 

men1ber is a more or less persistent layer of Railway four-fifths of a mile to 1 mile east of 

highly fossiliferous calcareous sandstone of Pecan Gap, Delta County, where the aggrevarying thickness, which contains a moderately gate thickness revealed is probably 25 or 30 

large but as yet only superficially studied feet. The ~ecan Gap chalk is exposed stratimolluscan fauna. (See Pl. XXIX, B.) Some graphically above the sands in a cut about half 

beds of calcareous clay occur in the upper part a mile east of Pecan Gap. , 

of the member, between the indurated layer In the public road at Webb flill, on the 

and the overlying Pecan Gap chalk member. northward-facing slope of the ·South Fork of 

Several incomplete sections of the sand are Sulphur Creek, 4! or 5 miles south.west of 

described below. Wolfe City, tlie indurated layer exposed in the 

Wolfe City, I-Iunt County, is situated on the section 1! miles east by north of Wolf Cit.v caps 

sand, but only small, poor exposures were seen the hill and is underlain by about 30 feet of 

within the town limits. The following section, well-exposed yellowish-green calcareous sand, "' 

representing about th~ middle portion of the followed below by 40 or 50 feet of similar rnamember, is afforded by a cut of the Gulf, terial poorly exposed. 

Colorado .. ~ Santa Fe Railway, 1! miles ~ast · Exposures of the Wolfe City sand and the 

by north of Wolfe City. (See Pl. XXIX, B.) characteristic calcareous concretions were observed in and near the public road 1 to 2 miles 

Section in cut of Gulf, Colorado & Santa Fe Railway, 1! south of Kingston, Hunt County, in a publicmiles east by north of Wolfe City, Tex. 

Feet. road ditch, 4! or 5 miles north by east of Floyd, 

Wolfe City sand member of Taylor mad: 

Poorly exposed yellowish, highly calcareous 

sand from which woother many small irregular 

gray sandy concretions of calcium carbonate. 

Contains Exogyra ponderosa Roemer, Anomia 

argentaria Morton, and Ostrea plumosa Morton 

Irregular concretion·ary ln.yer ·of yellowishgreen fine highly fossiliferous sandstone. 

See list of fossils below .................... . 

Fine yellowish-green calcareous sand with 

poorly preserved fossil prints ...••••••••••••• 

Hunt County, and in hill slopes south of the 

Missouri, Kansas & Texas .Railway, about 2t 

miles west of Farmersville, Collin County. 

The Wolfe City sand member has thus been 

8 definitely traced from a point east of Pecan 

Gap, in Delta County, to a point southwest of. 

1

_

2

, Farmersville, in Collin County, though its 

boundaries have been only approximately 

6 determined. 
156 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

PECAN GAP CHALK MEMBER. 

The uppermost member of the Taylor marl 

in northeastern Texas consists of about 50 

feet of bluish-gray, slightly bituminous, more 

or less argillaceous and sandy chalk, weathering to light gray and white, to which the name 

Pecan Gap chalk member is here applied. 

The chalk contains a moderately large fauna, 

most species of which are poorly preserved. 

The lower 10 feet of the chalk is typically exposed in a cut of the Gulf, Colorado & Santa 

Fe Railway half a mile east of Pecan Gap, 

Delta County, where the section ..is as follows: 

Section in cut of Gulf, Colorado & Santa Fe Railway, half 

a mile east of Pecan Gap, Tex. 

Pecan Gap cha.lk·member of Taylor marl: Feet. 

Lima sp. 

Paranomia sp. 

Pholadomya sp. 

V enielHt sp. 

Crassatellites sp. 

Cardium spillmani Conrad. 

Gastrochaena sp. 

Xenophora leprosa Morton? 

Gyrodes sp. 

Anchurasp. 

Pyropsis sp. 

Volutoderma sp. 

Actaeon? 

Nautilus sp. 

Turrilites? 

.Baculites asper Morton? 

Baculites sp. 

A thickness of 5 feet of the chalk was examined in the bed of the south fork of Sulphur 

Creek near Wilsons Crossing, 4! or 5 miles due 

south of Wolfe City, and poor exposures were 

noted in public roads 1 to 3 miles west of WilBlue massive chalk, weathering to light gray 

and white, becoming ~andy, and containing 

many phosphatic casts of mollusks in the 

lower 2 or 3 feet (see list below) .....•.••••... 

Wolfe City sand member of Taylor marl: 

10 sons Crossing in Hunt County. The chalk 

outcrops in the vicinity of Whiterock, a village 

4 n1iles northeast of Kingston, Hunt County, 

2 where it is overlain by yellowish, somewhat 

sandy clay marl, and poor exposures of argil2 laceous chalk were seen in . places along the 

The fossils obtained from the Pecan Gap public road for 4 or 5 miles south by west of 

Fine yellow argillaceous sand with numerous 

borings filled with chalky material from 

above .................................... . 

Dark to almost black fine sandy clay, poorly 

exposed .................................. . 

chalk at this locality are listed below: Whiterock. The chalk also extends at least 2 

Cucullaea sp. 

Ostrea plumosa Morton. 

Exogyra .ponderosa Roemer. 

Anomia argentaria Morton. 

Crassatellites sp. 

Cardium sp. 

Gastrochaena sp. 

Gyrodes sp. 

Anchura sp. 

Volutoderma sp. 

Actaeon sp. 

Nautilus sp. 

Baculites asper Morton? 

Baculites sp. 

Another good exposure of the chalk is in 

the bed and banks of a small stream on the 

Cox place, 3 miles east by south of Wolfe City. 

Here the fresh chalk is bluish gray and slightly 

bituminous, and weathers light gray and 

white. The maximum thickness observed at 

any one place along the branch is 6 feet. 

Fossils were recognized a~ follows: 

Cucullaea sp. 

Inoceramus sp. 

Ostrea plumosa Morto11. 

Gryphaea vesicularis Lamarck, var. 

Exogyra ponderosa Roemer. 

miles north of Whiterock, where cisterns have 

been dug into a sandy facies of the member at 

several farmhouses. The chalk belt is crossed 

by the Missouri, Kansas & Texas Railway 

(McKinney branch) at Fa.rmersville, Collin 

County, small exposures appearing on and near 

the ·railway for a· mile or more both east and 

west of the station. The belt is also crossed by 

the St. Louis & Southwestern Railroad about 

midway between Nevada and Lavon, Collin 

County, where an outcrop of the chalk was seen 

in the bank of a small creek. 

The largest collection of fossils yet obtained 

from the Pecan Gap chalk WtlS made by :Mr. 

and Mrs. D. A. Saunders, of Greenville, Tex., 

on the Jim Burnett farm, 6 miles northwest of 

Greenville, 1 mile west of Kellog, Hunt County. 

This collection was sent to theN ational Museum 

for identification and was studied, though not 

critically, by the writer, who recognized the 

following forms, many of which were too poorly 

preserved for specific identification: 

Hemiaster aff. H. lacunosus Slocum. 

H emiaster sp. 

Serpula (two or more species). 
GEOLOGY OF NORTHEASTERN TEXAS AND SOUTHERN OKLAHOMA. 157 

Cucullaea (two or more species). 

Pteria sp. 

Inoceramus sp. 

Ostrea sp. 

Gryphaea vesicularis Lamarck, v!tr. 

Exogyra ponderosa Ro·emer. 

Exogyr'a ponderosa var. erraticostata Stephenson. 

Exogyra costata Say (a small, nontypical form). 

Pecten quinquecostatus Sowerby. 

Pecten sp. 

Anomia argentaria Morton. 

has not been traced across the interval, although an attempt was 1nade to find it south of 

Clarksville in Red River County. In view of 

the adverse evidence afforded by the faunas,. 

therefore, the assun1ption that the two chalks 

are identical and continuous is 11ot justified by 

the present known facts. 

NAVARRO FORMATION. 

Lima sp. The Navarro formation in northeastern 

'l'rigonia sp. Texas consists of marine calcareous shaly 

Pholadomya sp. clays, sandy clays, fine gray sands, and argil- Modiolus sp. 

Clavagella armata Morton? 'laceous sands with local indurated portions in 

Liopistha (Cymella) sp. the form of calcareous septaria or concretionary 

Liopistha protexta Conrad? sandstone layers.· These deposits are estiCuspidaria aff. C. jerseyensis Weller. mated to attain a thickness of not less than 800 . Crassatellites sp. f Th f · · b bl "bl f Radiolites austinensis Roemer. eet. e ormatiOn IS pro a Y suscept1 e o 

Tenea sp. separation into at least three members but has 

Cardium sp. not yet been studied in this area in sufficient 

Cyprimeria alta Conrad? detail, either stratigraphically or paleontoLegumen. ellipticus Conrad. logically, to admit of mapping the subdivisions, 

Martesia sp. even approximately. Plemotomaria sp. 

Gyrodes petrof3a (Morton). The lower 300 or 400 feet of the forn1ation 

Gyrodes sp. consists of gray calcareous shaly clay or marl 

'l'urritella sp. that produces a dark-gray or black soil and 

Anchura (two species). carries a distinctive fauna, the most significant 

Pugnellus sp. species of which are Exogyra canceUata Stephen- Pyropsis (two species). 

Uopeplum sp. son, found at several localities riear Cooper and 

Volutoderma sp. Greenville, and Anomia tellinoides Morton, 

Actaeon? found at one locality near the Texas & Midland 

Nautilus sp. Railroad 2 miles west of Cooper. This is the 

Baculites (two or three species).· 'l.'mrilites (two species). Exogyra cancellata subzone, which forms the . 

Scaphites (three or four species). basal part of the E. costata zone and which has 

Corax falcatus Agassiz (shark teeth). been traced throughout the Atlantic and Gulf 

Lamna sp. (shark teeth). Coastal Plain fron1 New Jersey to Kaufman 

Gordon 1 recognized the chalk member to County, Tex., and has been recognized at 

which the nmne.Pecan Gap is here applied, but Ciudad del Maiz, San Luis Potosi, Mexico, 

he regarded it as a part of the Navarro forma- about 440 n1iles south of Eagle Pass, Tex. This 

tion and correlated ·it with the "Saratoga" subzone is represented in southwestern Arkanchalk member of the Marlbrook n1arl of south- sas by the upper half or more of the Marlbrook 

western Arkansas. The Pecan Gap fauna, 1narl with the exception of approxi1nately the 

however, belongs to the upper part of the upper half of the "Saratoga" chalk member, 

E'xogyra ponderosa zone, whereas that of the which fonns the upper 20 to 25 feet of the 

"Saratoga" is referable to the upper part of the Marl brook. 

E. cancellata subzone of the Exogyra costata The basal clays of the Navarro are overlain 

zone, which is definitely younger and higher .. bY fine gray sands and more or less sandy clays, 

The possibility is recognized that the Pecan .100 feet or more in thickness, which have been 

Gap chalk n1ay transgress ~pward in the geo- only s':lperficially studied in northeastern Texas, 

logic colunm fr01n Delta County, Tex., east- where they have yielded only a few poorly pre-. 

ward toward Arkansas, being continuous with served fossils. These beds correspond approxthe "Saratoga" chalk in Arkansas; however, it imately to the N acatoch sand of southwestern 

1 U.S Geol. Survey Wnter-Supply Paper 276, p. 26, 1911. 

28288°-19-11 

Arkansas, which carries a moderately lurgn 
158 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

fauna, and to the sandy beds in the vicinity of 

Kaufman County and near Chatfield and Corsicana, Navarro County, Tex., which have 

yielded a large and 'incompletely described 

fauna. The sandy beds are therefore to be 

correlated approximately with the middle 

portion of the Exogyra costata zone of the. Atlantic and Gulf Coastal Plain. ~ 

Farther south in Texas, from the vicinity of 

Corsicana, Navarro County,t to Mexia and 

Groesbeck, Limestone County, 2 sand that has 

been correlated with the N acatoch sand of 

Arkansas is overlain by over 500 feet of shaly 

clay that probably represents the Arkadelphia 

clay of Arkansas. This higher clay has not 

been recognized within the area shown on 

. the map accompanying the present report, and 

there is some evidence that it has been c:ut out 

by a northwestward overlap of Eocene strata. 

The boundary between the Navarro formation 

and the Eocene has, however, not been traced 

in detail in this area. 

TERTIARY SYSTEM. 

EOCENE SERIES. 

The southeastern part of the area under consideration, including most of Hopkins County 

and the southeastern part of Hunt County, is 

underlain by deposits of sand and clay of 

Eocene age, belonging in part to the Midway 

formation and in part to the Wilcox formation, 

which overlies the Midway. The Midway 

rests upon the Navarro formation of the Upper 

Cretaceous, from which it is separated by an 

erosion unconformity representing a long interval of geologic time. This statement is· based 

not upon observations made in this particular 

area, .where the contact has not been accurately determined and traced, but upon the 

known fact that throughout the Atlantic and 

Gulf Coastal Plain the unconformity separating 

Upper Cretaceous deposits from the overlying 

Eocene represents a very long time, during 

which this vast region was above sea level 

undergoing erosion, prior to the later marine 

submergence and deposition of Eocene strata. 

1 Matson, G. C., and Hopkins, 0. B., The Corsicana oil and gas field, 

Tex.: U. S. Geol. Survey Bull. 661, pp. 218-221, pis. 19 and 20, 1917. 

2 Matson, G. C., Gas prospects south and southeast of Dallas: U.S. 

Geol. Survey Bull. 629, pp. 21, 22, pl. 7, 1916. 

STRUCTURE. 

GENERAL RELATIONS AND ATTITUDE OF THE 

DEPOSITS. 

An examination of a generalized ge0logic 

map of the south-central United States woulll 

show that the vast stretch of the Coastal Plain 

bordering the Gulf of Mexico is underlain by a 

series of sediments of Cretaceous, Tertiary, and 

Quaternary age, and that north and west of the 

Coastal Plain in Arkansas, Oklahoma:, and 

central Texas rocks of much greater age, formed 

during Paleozoic and pre-Paleozoic time, appear 

at the surface. In reality the ancient rocks 

underlie the entire Gulf region, forming a supporting basement for the younger rocks, which 

overlap and conceal them as far northward and 

westward as would be indicated on the generalized geologic map. Along this boundary the 

upper peneplaned surface of the ancient basement rocks dips beneath the younger deposits, 

becoming deeper gulfward until along the coast 

it probably lies too deep. t9 be reached by 

modern well-drilling methods. 

In the area in northeastern Texas now 

under consideration the basement rocks do 

not appear at the surface, but tliey outcrop 

farther north, 10 to 30 miles north of Red River, 

in the southeastern part of Oklahoma, and farther west, in Montague and Wise counties, Tex. 

In the northwestern part of the area shown on 

the geologic map (Pl. XVII) the basement 

rocks lie in places within 350 feet of the surface, 

and in the southeast corner of the area, where 

their depth is greatest, they are estimated to 

lie between 4,000 and 5,000 feet below the 

surface. 

The dip of the upper surface of the basement 

rocks ranges from 40 feet or less to the mile 

in- the western part of the area to 70 feet or 

more to the mile in places in the east-central 

part. At Bowie, Montague County, Tex., 

near the western edge of the outcrop of Cretaceous rocks, the altitude of the surface of the 

basement rocks is approximately 1,100 f~et 

above sea level; at Farmersville, Collin County, 

90 miles east by south of Bowie, the basement 

is estimated to lie about 2,800 feet below sea 

level, making a general dip of 43 feet to the 

mile in the intervening area. Near Boggy 
GEOLOGY OF NORTHEASTERN TEXAS AND SOUTHERN OKLAHOMA. 

Depot, in Atoka County, Okla., the contact 

between the bas~ment rocks and the overlying 

.Cretaceous strata is about 550 feet above sea 

level; ne~r Wolfe City, I-Iunt County, Tex., 64 

miles south by east of Boggy Depot, the basement rocks are estimated to be 2,800 feet 

below sea' level, indicating a general dip of 

52+ feet ~o the mile. Locally, however, the 

dip of the basement surface is probably much 

greater than 52 feet and may reach several 

hundred. feet to the mile. These figures are 

based partly on assumed thickllesses, particularly of the formations composing the Comanche 

series, and are subject .to correction when the 

facts are known. 

The geologic map (PL. XVII) shows that 

the strike of. the beds composing the Cretaceous formations of northeastern Texas is approximately ~ast in the e,astern parts of Lamar 

~nd Delta counties; it swings around toward 

the south, farther west and southwest, in Fannin and Hunt counties; and becomes south by 

a few degrees west in the southern parts of 

Hunt and Collin counties. The dip is gulfward at right angles to the strike except locally, where the normal attitude of the beds 

has been disturbed by earth movement.s. The 

general dip is probably somewhat less than the 

inclination of the surface of the basement 

rocks on which the Cretaceous beds rest.. The 

general range of dip is believed to be from 30 

feet or less to the mile to 80 f~et or more to the 

mile, but there is evidence that locally, as 

along the southern limb of the Preston anticline near Pottsboro, the beds may dip as much 

as 300 feet to the mile. 

. 'l"he uniform monoclinal attitude which so 

generally characterizes the Cretaceous formations of the Gulf Coastal Plain is interrupted 

in this area by at least two pron.ounced deformations, the Preston anticline and the LeonardCeleste monoclinal nose, which are described 

below. Other similar deformations, · though 

probably much smaller, ;may be discov.ered as 

a result of future more detailed investigations. 

Faulting of small magnitude occurred in 

places in the area.,· probably a.s a result of the 

movements which produced the folds; positive 

evidence of small faults was obtained at several 

localities. The building-stone facies of . .the 

Annona tongue of the Austin chalk exposed in 

the quarries and small branch streams at and 

within a few hundred yards southeast of Gober, 

in the southern part of Fannin County, is considerably disturbed by faults of small displacement;, one fault running approximately 

nor.theast exhibits a displacement of 15 feet. 

At the.crossing of a public road over Choctaw 

Creek 3i miles north by east of Luella, Graysqn County, a fault trendi)lg N. 55° E. ~xhibits 

a displacement of 8 inches. Mes~rs. Hopkins 

and Powers indicate on their structure map. a 

fault of relatively small displacement southeast of Bonham, Fannin County, which involves the basal strata of the Annona tongue 

and the clay that immediately ~nderlies the 

cha).k. (See Pl. XVII.) 

PRESTON ANTICLINE. 

The Preston anticline is a plunging upfold of 

Cretaceous strata that is most conspicuous in 

the southern parts of Marshall and Bryan counties, Okla., and the northern part of Grayson 

County, Tex., but is measurably manifested in 

the direction of its southeastward-trending axis 

as far as the vicinity of G,ober in Fannin County, 

Tex. The approximate position of the axis of 

the anticline is indicated on Plate XVII by a 

dashed line. 

Where the anticline is best developed in the 

Red River valley, northwest of Denison, the 

Comanche series of formations, which .would 

normally be buried beneath the overlapping 

younger ;strata of th~ Gulf. series, have been 

warped upward approximately 800 feet, and 

the beds of the overlying Gulf series have thus 

been subjected to erosion, which has entirely 

removed not only the Gulf series but also much 

of the underlying Qomanche series from a considerable area along the axis of the uplift. 

Here the outcrops of the formations of the 

Comanche series parallel the sides of the a,nticline and wrap about its southeastward-plunging nose in typical fashion; the strike of the 

formations of the area, which would normally 

range from west to southwest, is distinctly 

bowed to the southeast where the formations 

cross the axis of the anticline, and this deflection of the strike is manifested at least as 

far to the southe.ast as Gqber, Fannin County. 

From the vicinity of Preston Bend in northern Grayson County, where the maximum uplift of the Cretaceous strata above the position 

they would have occupied had there been no 

folding is approximately 800 feet, the amount 

of deformation gradually decreases to the south-
160 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

east along the axis of the fold, and near Gober, deflection to the northwest of the several sets 

Fannin County, the uplift is very slight. of contours. A structural terrace on and 

Section A in Plate XXX is drawn approxi- slightly south of the plunging nose of the antimutely at right angles to the axis of the anti- cline is indicated by the spacing of the contours 

cline from a point near the northeast corner of 2 to 6 miles northeast of Pottsboro, Grayson 

the Denison quadrangle, in Bryan County, County. 

Okla., southwest to a point 3! miles north of The dip of the strata of the Comanche series 

Fink, Grayson County, Tex., thence south to a away from the axis of the 'Preston anticline 

point 1 mile north by west of Pottsboro, thence ranges from a few feet to a little more than 300 

south-southeast to Sherman. The surface feet to the mile. In general, the south limb 

profile is based on the data recorded on the is a little steeper than the north limb. The 

Denison topographic map, and the structure steepest part of the anticline is on the south 

lines are based partly on outcrops and partly limb in a northwest-southeast stretch about 3 

on data afforded by wells. This section is miles long northeast of Pottsboro (see Pl. 

believed to be approximately accurate where XVII), where, as .indicated by the contours, 

it crosses the main part of the anticline north. the maximum dip of slightly more than 300 

of Pottsboro, the position of the lines there feet to the mile is attained by the Goodland 

having been checked against the structure con- lim~stone. This relatively strong dip is. also 

tours established by Messrs. Hopkins and clearly manifested in outcrops of the Main 

Powers. (See Pl. XVII.) Street limestone, the next to the highest memThe structure contours shown on Plate XVII her of the Denison formation, whose strata in 

are generalized from larger-scale maps prepared conjunction with the ''Quarry" limestone form 

by Messrs. Hopkins, Powers, and Robinson, as a low strike ·ridge beginning about 2 miles east 

elsewhere explained. Their method was to de- of Pottsboro and extending in a northwesterly 

termine the altitude of key rocks at as many direction for about 2 miles. Along this ridge 

points as possible, by means of aneroid readings the Main Street limestone, though poorly excorrected for changes of atmospheric pressure . posed, obviously dips strongly to the southby barograph records obtained simultaneously west, in places as much as 20° or even more. 

at the bases from which the field work was The pronounced narrowing in the belt of outdone, and to supplement these surface obser- crop of the Woodbine formation resulting 

vations with data afforded by all available from the unusually steep inclination of the 

well records. strata in this belt was perhaps the chief 

The contours on the main part of the. Preston basis for the postulation of the so-called 

anticline in the northern part of Grayson Cook Spring fault by Taff 1 and Leverett and 

County, Tex., and the southern parts of Mar- by Hill. 2 

shall and Bryan counties, Okla., show the The nature of the earth movements that proaltitude above sea level of the top of the Good- duced the Preston anticline is imperfectly 

land ·limestone. The extension of the anticline known, though the assumption is warranted 

into Fannin County is indicated by the south- that the movements had tneir origin in the 

eastward' deflection of the contours showing basement rocks that underlie the overlapping 

the altitude of the base of the Ector tongue of Cretaceous sediments. As the axis of the antithe Austin chalk in the vicinity of Ector, by a cline trends approximately parallel to m~st of 

less pronounced deflection of the contours the major faults and folds ·in the Arbuckle 

showing. the base of the Annona tongue of the Mountains in Oklahoma~ the assumption also 

Austin chalk between Dodd City and Randolph, seems warranted that this uplift is directly reand by only· a faint bending of the contours lated to the Arbuckle uplift, and that the foldshowing the top of the Annona tongue north- ing of the Cretaceous strata was merely incieast of Gober. The last-mentioned place is dental to the upbowing of these older basement 

approximately at the point where the anticline rocks. 

dies out toward the southeast. A shallow 

syncline parallels the anticline along its northeast side in Fannin County, as indica ted by a 

1 Texas Geol. Survey, Fourth Ann. Rept. for 1892, pp. 297, 298, 1893. 

2u. S. Geol. Survey Twenty-first Ann. Rept., pt. 7, pp. 384, 385, pi 

66, 1901. ' 
GEOLOGY OF NORTHEASTERN TEXAS AND SOUTHERN OKLAHOMA. 161 

LEONARD-CELESTE MONOCLINAL NOSE. of Farmersville, Collin County, shows this upbowinO' of the strata ill the vicinity of Celeste. 

The structure contours showing the altitude ·The s~face profile in this section is based in 

above sea level of the top of the Annona tongue part on railroad elevations and in part on anerin the vicinity of Leonard in southwestern oid barometer readings, and the structure lines 

Fannin County, Tex., are deflected rather· are based on surface outcr.ops and on data 

sharply to the south. (See Pl. XVII.) This afforded by the wells at Celeste and Wolfe City 

deflection is also clearly manifested in the out- previously mentioned and by one well at Lacrop of the Annona, the strike of whose upper- donia. The depth to the Woodbine in these 

most beds in the vicinity of Leonard shows a three wells, if their logs are properly interpreted, 

distinct bulge to the south. A similar and even apparently confirms the evidence afforded by 

stronger southward or southeastward deflec- the chalk. At the southwest end of the section 

tion is exhibited by the belts of outcrop of the near Farmersville the Annona, as estimated 

Wolfe City sand and Pecan Gap chalk mem- from surface outcrops and assumed thicknesses, 

hers of the Taylor marl between Celeste and has again sunk back to a level approximately 

Greenville, in I-Iunt County. (See Pl. XVII.) the same as near Wolfe City, or a little deeper. These are the surface manifestations of a· fold 

in the underlying Cretaceous strata of. the kind OIL AND GAS PROSPECTS·. 

described by F. G. Olapp 1 as a monochnal nose. Oil and gas have frequently been found in the 

For convenience this fold is called the Leonard- upbowed or anticlinal portions of strata that 

Celeste monoclinal nose. The areal distribu- h~ve been subjected to warping or folding by 

tion of the formations of the Gulf series in earth forces, and although these substances 

Fannin, Collin, and Hunt counties strongly are not confined exclusively to such structural 

suggests that this fold is the deflec.te~ south- features, no argument is needed to convince 

ward extension of the Preston antiChne, and the practical operator that his best chance of 

this was the interpretation at first placed upon success in untested territory lies where folded 

the structure. However, the structure con- strata are known to exist. The Preston antitours on the base of the Annona tongue estab- cline and the Leonard-Celeste monoclinal nose, 

lished by Messrs. fiopkins and Powers (see described above, will therefore not fail to atPl. XVII) indicate that this relationship is only tract the attention of persons interested in the 

apparent, the Leonard-Celeste fold being sep- discovery of reservoirs of oil and gas. 

arate from the Preston anticline, though In this paper only the more obvious condoubtless closely related to it both physically elusions in regard to tlie occurrence of oil an~ 

and in manner and time of origin. The axis gas, which might be readily deduced by any ml 

of the fold appears to trend south by east geologist or practical oil operator from the facts 

through Leonard i,tnd a mile or so west of already presented, will be brie~y discussed. 

Celeste and Kingston, Tex. · A more detailed discussion of the structural 

The surface evidence of the existence of this features of this area and an adjoining area on 

fold appears to be corroborated by the ·records the northwest in Oklahoma, with particular 

of two wells nearly in line with the general reference to the occurrence of oil and gas in 

strike of the formations-one near Wolfe City, both the Cret~ceous and underlying basement 

where the top of the Annona tongue of the rocks, will be given by Messrs. Hopkins, Powers, 

Austin chalk was struck at a depth of about and Robinson in an economic pttper to be pub510 feet (160 feet above sea level), and the other lished la.ter. 

at Celeste, where the Annona was reached at The most conspicuous part of the Preston 

a depth of only 300 feet (360 feet above sea anticline, in Grayson County, Tex., and 

level). Section B, in Plate XXX, drawn Marshal] and Bryan.counties, Okla., has already 

approximately at right angles to the axis of been recognized by oil prospectors, and 

the fold, from Ladonia, Fannin County, west test wells have been drilled on different parta 

by south to a point It miles northeast of Wolfe of the up1ift. Gas reported to come from the 

City, in Fannin County, thence southwest by lower part of the Trinity sand at deptl).s of 

way of Celeste ton point 2 miles west by north less than 700 feet has already been discovered 

1 Oeol. Soc. America Bull., vol. 28, p. 572, fig. 8, 1917. near the axis of the anticline in the southern 
162 SH\)RTE~- CON:TRIBUTIONS TO GENERAL GEPLOGY, 1~18. 

part of Marshall County, .. where at least a 

dozen test wells ·have· been dtilled. Of these 

wells ·six, located in a: group·. i~.,the' southeast 

corner ofT: 6 S.~ R. 5 E·.-, ·_and the northeast 

cor~er of ,T. 7 S~; R: '5 E'., ·.a.re classed as pro..: 

clueing gas wells', and each :of three of them is 

reported· to yield fron1 1,500,000 to 2;500,000 

cubic feet of' gas d'all3t; This pool is known as the 

Enos gas field. · In June, 1918, an oil welfnear 

the crest of the ·anticline in sec. 23, T. 7 S.; 

R. 5 E., was completed in the Trinity sand at 

n depth' ·of 260 feet and was reported to produce' 20:barrels of oil daily. Showings ·of oil 

o·r gas,-orboth, have been reported from the 

Trinity sand in some of the other wells penetrating the strata involved in the anticline. 

The Madill oil field, 1 farther north in Marshall 

County, in the southeast corner ofT. 5 S., R. 5 

E., which yields small commercial quantities of 

an ~xceptionally light grade oil from the Trinity 

sand, 2 is not connected with the Preston anticline but with another distinct though approximately parallel fold, as shown by an unpublished structure contour map prepared by 

Messrs. Hopkins, Powers, and Robinson. 

Of the geologic subdivisions involved in the 

· Preston anticline and its ·extension to the 

southeast in F.annin County, four are composed in part of sandy strata, which exhibit a 

sufficient degree of porosity, at least in their 

outcropping portions, to fit the¢ to serve as 

reservoirs for the storage of oil or gas. . They 

aret iri ascending order, the Trinity sand, the 

Pawpaw sandy member :of the Denison formation, the Woodbine sand, and sandy beds in 

the upper part of the Eagle Ford clay. 

The occurrenc~ of gas an'd some oil in the 

Trinity sand along the axis of th~ fold in 

the southern part of Marshall County, Okla., 

has already been demonstrated. The amount 

of gas and the volatile products of oil that 

may· once have been contained in the sand 

and have since escaped where the formation is 

exposed in the cr~st of the fold cari; of c~urse, 

only be conjectur.ed. The Trinity dips below 

the surface oil the plunging nose of the anticline ,in the Red River valley, about 51 miles 

n'orth by west of D(mison. 

a Taff, J. A., and Reed. W . .I • The Madill oil pool, Okla.: U.S. Geol. 

Survey Bull. 381, pp. 504-513, 1910 2 Oklahoma Geol. Survey Bull. 19, pt. 2, pp. 316-320, 1917. 

A travel.~r pa~~ing_to the southeast along the 

axis. of t~.e ariticJiJ.?.~ would cross successively 

the out~ropp~ng strata of the sandy fqrmations 

mentione~ ,above, with intervening bands of 

nonsandy clay ~nd. chalk, each in turn dipping below t~e surface down the nose of the 

anticline. After crossing the limestones and 

clays of .the C<?manche series above the Trinity 

he would come first to the narrow belt of sand 

of the Pawpaw sandy member of the Denison 

formation near the northeast corner of Grayson County, the wider sandy belt of the Woodbine in the :q.orthw~st corn~r of Fannin County,' 

and the narrow st~ip of sand forming the 

uppermqst part of the Eagle Ford formation 

at Ector, in Fannin County. 

A well on the axis of the anticline near the 

northwestern part of .Fanni~ County would. 

start in th~ Woodbin~ sand, below which it 

woul~ e_ncounter two of the possible oil or gas 

bearing sands, the Pawpaw and the Trinity. 

The top of the Pawpaw would probably be 

reached at depths of 50 to 500 feet and the 

top of the Trinity at depths of 500 to 1,000 

feet, the depth depending on the exact location 

of the well. .. 

A well at Ector would start in the sand at the 

top of the Eagle Ford and would penetrate the 

Woodbine sand at an estimated depth of _490 

to 900 feet, the sandy beds of the Pawpaw at 

an estimated depth of 925 to 975 feet, and the 

Trinity sand at an estimated depth of 1,300 to 

1,800 feet. 

A well starting at the top of the Annona 

chalk northeast of Gober would penetrate the 

sandy beds at the top of the Eagle Ford at an 

estimated depth of 800 to 900 feet, the Woodbine sand at an estin1ated depth of 1,300 to 

1,850 feet, the sandy beds of the Pawpaw ~tan 

estimated depth of 1, 900 to 1, 950 feet, and 'the 

Trinity sand at an estimated depth of 2,300 to 

2,800 feet. · 

So far as known to the writer no wells have 

been drilled that would serve as an adequate 

test of the occurrence of oil or gas in the 

Leonard-C~leste monoclinal fold. The deepest 

well concerning which information has been 

obtained is the 1,554-foot water well at Celeste, 

perhaps a ffiile or a mile and a half east of the 

a.xis of the fold. This well is believed to have 

reached the uppermost sandy stratum of the 
GEOLOGY OF NORTHEASTERN TEXAS AND SOUTHERN OKLAHOMA. 163 

Woodbine formation at a depth of 1,535 feet. 

The sandy beds at the top of the Eagle Ford 

were not recognized in the well and may here be 

represented by nonsandy clay. The sandy 

beds of the Pawpaw would be reached here at 

an estimated depth of 2,200 feet, and the top 

of the Trinity sand at an estimated depth of 

2,600 feet. 

At Greenville, which is probably near the axis 

of this fold, all the possible oil sands o.f the 

Cretaceous, except the Nacatoch, would be 

penett·ated by a well probably less than 3,500 

feet deep. 'l'hese would include, in descending 

order, the Wolfe City sand member of the 

Taylor 1narl, the sandy 1nember at the top of 

the Eagle Ford; which would probably be very 

thin and 1night be represented entirely by 

clay; the sands of the Woodbine fonnation; 

the Pawpaw sandy 1nember of the Denison; 

and, finally, the Trinity sand. 

In pointing out the existence of the folds described above the writer does not wish to be 

understood- as urging the probability of the 

occurrence of oil and gas in association with the 

folds, though he feels that the facts warrant an 

optimistic attitude on the subject. 

Four factors are generally regarded as essentin.l to the occurrence of oil and gas-an adequate source of hydrocarbons, such as petroliferous shales or clays; porous beds intimately 

connected with the source to serve as reservoirs; suitable structure for the concentration 

of the oil and gas; and suitable hydrostatic 

conditions. Two of these factors appear to be 

favorable in this area; porous formations for 

the retention of the oil are present, and structural folds exist similar to those in which oil and 

gas are known to have accumulated elsewhere. 

The factor of source, although less completely 

known, also appears to be favorable, for the 

chalks and some of the clays that intervene 

between the sandy forn1ations are distinctly 

bituminous. In regard to the fourth factor, 

there is no known reason why the ground-water 

conditions in the Cretaceous beds of this area 

should be essentially different from those of the 

other oil and gas fields of the Gulf Coastal 

Plain. 

! , \ .. 

SUMMARY. 

1. Areal geology.-Important revisions in the areal distribution of the formations of both the Comanche and Gulf 

serie8, as previously mapped in this area, are indicated in 

Plate XVII, and three new mappable units are recognized, 

including the Ector tongu~ of the Austin chalk and the 

YVolfe City sand member and Pecan Gap chalk member of 

the Taylor marl. . 

2. Stratigraphy.-A new interpretation of the stratigraphic and age relations of the formations of the Gulf 

series based on the following facts is present~d (see Pl. 

XXX, C): (a) The recognition of the· so-called "fish-bed 

conglomerate" ·of Taff (seep. 149) as the probable base of 

the cycle of sedimentation which has its typical expression in the Austin chalk; (b) The recognition of a relatively thin tongue of chalk, the Ector tongue, extending 

northeastward from the base of the main body of the 

Austin chalk in the vicinity of Ector, Fannin County; 

(c) the eastward merging of approximately the basal half 

of the Austin chalk, with the exception of the Ector tongue, 

into equivalent nonchalky clay in Fannin County; (d) 

the correlation of the Blosson1 sand with the upper part 

of the typical Austin chalk of Travis County, '!'ex., instead of with the upper part of the Eagle Ford formation, 

as previously correlated (see pp.l52-l53 and Pl. XXX, C); 

(e) the upward transgression in the geologic column of the 

upper part of the Austin chalk· from Travis County 

northward; (j) the recognition of the Ann01ia ("White 

Cliffs") chalk of Hill as a large tongue connected with the 

main body of the Austin chalk; (g) the discrimination of the 

Wolfe City sand and Pecan Gap .chalk as upper mappable 

members of the Taylor marl. 

3. Structure.-The structural feature in the northern 

part of Grayson County, Tex., and the southern parts of 

Marshall and Bryan counties, Okla., heretofore regarded 

as an uplifted fault block w.hich brought the formations 

of the Comanche series to the surf~~tce, where normally 

they would lie deeply buried, is shown to be instead an 

anticlinal uplift, the Preston anticline, with which, so far 

as known, no major faults are directly associated. A 

newly recognized structural feature, called the LeonardCeleste monoclinal fold, in southwestem l<'annin and 

northwestern Hunt counties, is described. St!ucture 

contours have been established by .Messrs. Hopkins, 

Powers, and Robinson, sho\ving the altitude above sea level 

of the top of the Goodland limestone about the flanks 

of the Preston anticline, and .Messrs. Hopkins and Powers 

have established contours showing the altitude of the base 

of the Ector tongue and the base and top of the Annona 

tongue of the Austin chalk in certain areas ·in Fannin, 

Grayson, and Hunt counties. (See Pl. XVII.) 

4. Oil and gas.-A brief statement of the factors controlling the occurrence of oil and gas with particular 

reference to this area is given, and the hope is expressed that 

future. prospecting may result in the discovery of these 

substances in commercial quantities somewhere in association with the Preston anticline or with the LeonardCeleste monoclinal fold. 
,,,, 
SOME AMERICAN CRETACEOUS FISH SCALE.S, WITH NOTES ON THE 

CLASSIFICATION AND DISTRIBUTION OF CRETACEOUS FISHES. 

By T. D. A. ·CocKERELL. 

PREFACE. 

·By T. W. S·rANTON. 

scales have been obtained f.rom the Mowry 

shnJe, fron1 the Aspen shale, and from other 

beds of about the same age in. the areas where 

Fish ren1ains are extre1nely ~bundant in these shales are not characteristically develseveral Cretaceous forn1ations of the Rocky oped, but no attempt has been made to do 

Mountains and Great Plains, but except in thorough collecting even in these formations, 

the Niobrara formation of Kalfsas, a fish because no one in the Survey was qualified to 

skeleton well enough preserved for descrip- identify the scales .. The scales from other 

tion or identification is the greatest rarity. formations in the same region have been 

The fishes are represented by separate scales, obtained incidentally in collecting invertebrate 

in son1e places associated with a few vertebrae fossils and are so few in number that they 

and other frag1nentary bones or by isolated probably do not fairly represent the fish 

teeth. In the. original descriptions of both faunas of the seas in which the formations 

the Mowry and the Aspen shnJes of Wyoming were deposited. Sin1ilarly, the four species 

the presence of fish scales is mentioned as a based on scales fron1 the Chico group were all 

characteristic featm·e. Fossils of other classes obtained in the Moreno formation at two 

are usually very rare in beds containing 1nany neighboring localities on the west side of San 

fish scales. :Many of the scales are benutifully cJoaquin Valley, Cal., and can only be regarded 

preserved and show vn.ried forn1s and1nore or as suggestive of the relationship, or lack of 

less c01nplex sculpture. relationship, between the Cretaceous fish faunas 

It had long been regretted that these fish of the Pacific coast and those of the Rocky 

scnJes had not been st;udied syste1natically, Mountain region. The enormously thick secand when several papers on _the scales of tion referred to the Chico group in this part of 

living and fossil fishes were published by Prof. California has been .divided by Anderson and 

Theodore D. A. Cockerell/ of the U~1iversity of Pack 2 into the Pn,noche formation below and 

Colorado, Boulder, Colo., the hope was again the Mo·reno formation at the top. The Paquickened thn,t these Cretaceous fi~h scal~s noche for1nation is said to have a maximun1 

:might prove to be of son1e value. In strati- thickness of 21,000. feet and the Moreno formagraphic identific~1tions 11.11d correlatiOn. Prof. tion 2,500 or 3,000 feet. Fish scales are known 

Coekerell's offer to study fish_ scales collected to be present in the Cretaceous formations of 

by the United States Geological. Surv~y was 1 the Coastal Plain, extending fro1n New Jersey 

therefore welcomed, and early In 1916 the to Texas, but no attempt has yet been made 

material fron1 the Western States was placed to assemble them for study. The collections 

in his hands. As a result of its study the ac- here treated are all of Upper Cretaceous ageCOinpanying paper has been prepared. that is they are younger than the C01nanche 

In connection with the Survey's stratigraphic and Shasta series. 

and areal wod< on the coal and oil fields of the A brief statement will show the relative 

Rocky Mountain region n1any s1nalllots of fish stratigraphic positions. from ·which the fish 

1 ~L'ho scales of fresh-water fishes: :Bioi. llull., vol. 20, pp. 367-386, 

.Hill. Observations on fish scales: U. S. Bur. Fisheries :Bnll., vol. 32, 

pp. 119-174, 1912. Somo fossil fish scales: Zoo!. Anzeiger, Band 45, pp. 

189-192, Hl14. Scales of Panama fishes: Washington Bioi. Soc. Proe., 

vol. 28, pp. 151-159, 1915. 

scales described have been obtained and will 

explain why beds of approxin1ately the same 

2 U.S. Geol. Survey Bull. 603, pp. 34-57, 1915. 

165 
. I 

.i, 

~' 

166 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGYf 1918. 

age are referred to different formations in different areas. The standard marine Upper 

Cretaceous sectiqn of· the Upper MisE~our.i~ 

regi9n.is as follows: 

Montana group: 

Adaville formation. 

Hilliard shale .. 

·Frontier formation. 

Aspen s:hale .. ' 

· Be·ar River formation (restricted to western Wyoming). 

·. Fox Hills sandstone. 

Pierre shale. In this section the time equivalent of the 

Colorado group: Co'lorado group extends from the top of the 

Niobrara limestone. Bear River formation to about the middle of 

Benton shale: the Hilliard shale, and the upper part of the 

Dakota sandstone. . :Montana group is probably absent. In westIn Colorado east of the Rocky Mountains ern Colorado the whole of the Colorado group 

·aild. over a· considerable part of 'the Great , and the lower part of the Montana group· are 

·· Plains a limestone (Greenhorn limestone) . is represented by an· undivided mass of shale 

developed in the midst of the Benton shale, so called the Mancos shale, and this is overlain by 

that the Benton shale interval consists of three the coal-be.aring Mesaverde formation, folformations-th~ Carlile sh~le, Greenhorn lime- lowed by the Lewis shale and in the southstone, and Graneros shale. In parts of the west· by the Pictured Cliffs sandstone. The 

· saine area· the Niobrara is also separable into_ Mesaverde formation is also recognized over a 

'two formations-~~e · Apishapa shale. above large ·part of Wyoming, and the only fish 

~'tnd the ·Tim pas limestone below. . . . . . scnJes found in it were obtained in marine 

In the ·eastern luilf ·of.Wyoming atid around and brackish-water beds of the Rock Springs 

the Black Hills the Mowrfshale is conspicuous field. . . 

in the lower part of the: ·polorado group as a Another set of names has been used in northhard, .platy, ·ridge~t<;>rmlliif ·shale, :full of fish ern Montann on account of the development 

s·cales. Tti ·the ·Black Rills, where the Gre~n- , of· different stratigraphic units. There the 

horn lll;ne.stcnie,is re'c'ognized and the Benton. js great shale mass corresponding to the ·Mancos. 

· therefor~·· divisible into three form~tions, the extends only to the top of the Colorado group· 

'Mowry shale ·is treated as a member of the and is t~erefore called the Colorado shale. 

Gran~ros''i'shale. · ln som.e areas· where the . Above it in order come th~ Eagle sandstone, 

· Bent~n is not divided. the ·Mowry is. cnJled a the Claggett shale, the Judith River formation, 

; member of the Benton; 'iii the Big Horn Basi1~ and .the Bearpaw shale. Locally this succes-

.. ' . it .. is' recognized as an independent formation sion is modified by the merging of the Claggett 

lying between· the Frontier formation above with the ·Eagle and Judith River and the deand the· Thermopolis shale below. ve.lopment of the Horse thief sandst9ne above 

The Aspen shale, which certainly includes the Bearpaw.shale. 

rocks of the same age as the Mowry shale, is The approximate relations of the aboverestricted to west'ern Wyoming, which is also mentioned local subdivisions of the Colorado 

the typical area of the Frontier formation. and Montana groups ·are shown in the follow-· 

The section there is as follows: ing table: 

~y·. 

• ., '· .j I. ' ·~ ' 

.&J;.:j~; t "~ ·q; . :.:J'd '.:: tj ·! '"• 

f.!'l. 
p., 

g 

So 

<:6 

fJ 

"'"" ~ 

0 

~ 

ci. 

;:::l 

0 

So 

0 

'\j 

<:6 

s 

0 

0 

Standard section, 

upper :Missouri 

region. 

Fox Hills sandstone. 

Pierre shale. 

Eastern Colorado. 

Fox Hills sandstone. 

Pierre shale. 

Apishapa shale. 

Niobrara limeston~.l 1 

Benton shale. 

Timpas limestone. 

Carlile shale. 

Greenhorn limestone. 

Graneros shale. 

Relations oj iocai suhdi'll'isions oj Coioraljo and Montana groups. 

Black Hills a_nd eastern I Southern Wyoming.! East side ~ Big 1 Western Wyoming.! Western·Colorado. I Northern Montana. Wyommg. Horn Basm. 

Fox Hills sandstone. 

Pierre shale. 

Niobrara formation. 

Carlile shale. 

Greenhorn limestone. 

IZl 

0 . 

Q}- '"' Q} 

~ <:6 c6,.l:l '"'lll C!i 

Mowry shale 

member. 

Lewis shale. 

Mesaverde formation. 

Steele shale. 

Niobrara shale. 

Carlile shaie. 

Frontier formation. 

Mowry shale. 

Meeteetse formation (fresh water). 

Pictured Cliffs sandsto~e 

(southwestern ·I Bearpaw shale. 

Colorado). ·' 

Lewis shale. 

. 

1 

I Judith .River·for- Mesaverde forma-~---------t ?) _c ___ . ____ Mesaverde forma- mation. 

tion. Adaville forma- tion. 

Cody shale. 

Frontier 

tion. 

formaMowry shale. 

tion. 

Hilliard shale. 

Frontier formation. 

Aspen shale. 

Claggett shal~: 

-Eagle sandstone·. 

Mancos shale. 

Colorado shale. 

Thermopolis shale. I 'l'hermopolis shale. 

r:n 

0 

~ trJ 

> 

~ trJ 

!::0 

..... 

0 

> 

z 

0 

~ 1-3 

> 0 

trJ 

0 

q 

'(fl 

l'%j 

..... 

'(fl 

tJ:1 

'(fl 

0 

> 

t-' 

t:<:l 

?2 

1-' 

~ 

-::J 

·-
168 SHOR~R CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

INTRODUCTION. 

In offering a treatment of Cretaceous fishes, 

based principally on isolated or detached 

scales, one runs counter to the practice and 

prejudice of ichthyologists. The old scale 

classification of ·~assiz has long been discarded 

and his terms are now used only in a descriptive sense. Even in that sense they are 

rather unsatisfactory, for there are many 

entirely different types· of cycloid, ctenoid, 

and ganoid scales. Recent studies of the 

scales of living fishes show that they present 

excellent diagnostic characters and are highly 

distinctive of genera .and families, though not 

. always of s·pecies. Very closely allied species 

may have scales which can not be distinguished, 

the scale characters being more persistent 

than some of the other more adaptive features 

on which the species are separated. Some 

scales, as might be expected, exhibit convergent 

or parallel evolution, showing similar features 

in quite different groups of fishes. Facts of 

this sort are likely to be misleading, but they 

are in no sense peculiar to lepidology. 

In former years a few authors have undertaken to diagnose or recognize Cretaceous 

fishes from the scales alone. Dr. A. S. Woodward, influenced no doubt by the evident 

confusion in the application of the names, 

has set aside these determinations as practically 

valueless. It was not possible to give a really 

intelligible account of the fossil teleost scales 

until those of living fishes had been rather 

fully investigated. To-day the situation is 

different, and we feel justified in proceeding 

on a new basis. The situation is not unlike 

that found in paleobotany. Students of living 

plants do not describe species from leaves 

alone except in the rarest instances. Yet, if 

paleobotanists had refused to take note of or 

describe all plant remains that did not include 

the reproductive parts, our knowledge of the 

past history of vegetation would to-day be 

fragmentary indeed. It is true that many of 

the generic references of fossil leaves are provisional and uncertain, and it is very easy to 

criticize any paleobotanic work on this basis; 

yet no careful student of the subject can deny_ 

that on the whole the study of fossil leaves has 

been of immense value for the advancement of 

botanic science as well as for stratigraphy. 

Mter spending much time in the study of fossil 

plants as well as fish scales, I can -affirm that 

the scales are certainly not less characteristic 

than the leaves; in fact, the comparison. is 

decidedly in favor of the scales. It can a~.~o 

be said that the scales are at least as distinctive 

as the fragments of jaws, teeth, and fins that 

for~ the basis of so many desctriptions of Cretaceous fishes. It is not, however, a question of 

scales versus bones, where both are available. 

Throughout the greater part of the American 

Cretaceous strata. distinctive skeletal remains 

of fishes are extremely scarce; only in the Niobrara can they be said to be at all abundant. 

On the other hand, scales are plentiful and 

widespread and may be found in innumerable 

places where no other fossils are obtainable . 

Consequently, to refrain f:r:om studying these 

scales is to set aside a valuable aid to stratigraphy as well as a chance of learning in considerable detail what the teleost fauna of the 

Cretaceous really was. The Cretaceous ·was a 

time of extraordinary importance for ichthyology, because it saw the rise and development 

of the higher fishes, with numerous types clearly 

pointing toward the modern fauna. For this 

reason it is especially desirable to note every 

fact which will throw light upon the Cretaceous 

history. 

The study of fossil scales involves one difficulty. In studying modern fishes the investigator takes the scales from the middle of the 

side of the fish, where all their characters are 

fully developed. Scales from other situations 

may be quite uncharacteristic. Naturally no 

such selection has taken place in the preservation of the fossils, and consequently the specimens must be regarded with caution and set 

aside if there is any reason to think that they 

are not typical. Scales from the region of the 

caudal peduncle will be comparatively narrow, 

but their sculpture and markings will be normal. · Latinucleate (regenerated) scales are as 

common among fossils as in recent fishes, and 

should not be used as types. They can be 

distinguished by the confused sculpture 'of the 

central region, without the fine circuli around 

the nucleus. . In describing scales the free end. 

is spoken of as the apex, the attached end as 

the base. The teleost scale is made up of fine 

fibrillae, which are in some genera longitudinal, 

as in Amia and Albula, but more usually concentric. In the trp.e clupeids (herrings) they 

are transverse. These fibrillae are termed the. 

circuli and are not grow:th lines. Growth lines 
SOME AMERICAN CRETACEOUS FISH SCALES. 169 

have often been observed cutting the circuli. 

In 1nigratory ·fishes, such as the salmon, the 

growth lines differ in character and density, 

according to the environment, and consequently it may be possible to detect evidence 

of migratory habits in fossil fishes. Lines or 

grooves radiating from the center of the scale 

or from its direction are called radii. This 

term was long ago used by Cope .in describing 

fossil fish scales; and it must be s.aid of Cope 

that his descriptions of these structures were 

much better than those of most other authors, 

though lacking in many desirable details. 

As in the case of fossil leaves, descriptions of 

scales without figures are unsatisfactory, especially if they are to be largely used by stratigraphers who have no intimate lmowledge of 

lepidology. Consequently it has been· considered necessary to illustrate this paper fully; 

and the enlarged figures, from photographs, 

bear testimony alike to the excellent preservation of much of the material and the skill of 

the photographer, Mr. W. 0. I-Iazard, of the 

United States Geological Survey. Only those 

species have been described and figured which 

it seemed could be clearly recognized. Various 

others, evidently distinct but represented by 

poor or uncharacteristic material, have been 

set aside for the present. Additional collections, now that attention is called to the subject, will undoubtedly greatly increase the 

number of lmown species. 

I am particularly indebted to Mr. T. W. 

Stanton, of the Survey, for assistance of every 

kind throughout this investigation. Without 

his kind help I should have found it very 

difficult to proceed. I am also greatly indebted to my colleague, Prof. J. Henderson, of 

the University of Colorado Museum, for advice 

and assistance. Dr. D. S. Jordan has given 

me much kind advice, though, of course, he is 

in no way responsible for my manner of treating the subject. I-Ie has furnished a manuscript list of all the families and higher groups 

·Of fishes, representing his most mature opinions. 

This I have mainly followed in the present 

paper. Dr. A. S. Woodward, of the British 

MuBeum, has sent me admirable photograph3 

·Of fossil fish scales, two of which I have reproduced (Pl. XXXVII, figs. 1, 2), and when I 

was in London he kindly gave me access to 

the collections of the Museum. Unfortunately at that time I did not know that I 

should be specially interested in Cretaceous 

fishes and did not pay particular attention to 

their scales, except in the case of a few genera. 

The authorities of the United States National 

Museum and the ·American Museum of Natural 

History very kindly allowed me to examine 

their materials. I am indebted to the University of Kansas for the photographs of 

Hypsodon (Portheus), reproduced in Plate 

XXXIII, figures 1 and 2. 

As students of fossil scales will need specimens of recent species, it may be worth while 

to explain a simple manner of preparing them. 

Remove a few scales from the middle of the 

side of the fish, avoiding regenerated scales, 

and place them, while wet, upon a slide. The. 

skin covering the exposed part should be removed if it is thick. Cover the scales with a 

.cover glass or, if th~y are large, with another 

slide. Hold down with one or more of the 

metal clamps used in microscopic work. 

Stick a gummed slide label on each side of the 

cover glass, overlapping, or, if two slides are 

used, round the ends of the slides. Remove 

the clamps when the material is dry, and the 

scales will remain in place. 

STRATIGRAPIDC DISTRIBUTION. 

GENERAL FEATURES. 

In this discussion we are dealing almost entirely with a marine fauna. Scanty remains 

from the Judith River beds (see Acipenseridae) 

are of fresh-water origin, but they do not include any t~ieost scales. It is not until we 

come to the base of the ~ocene, in the Rocky 

:Mountain region, that we find scales of freshwater bony fishes/ and the species obtained 

present all the characters of the highly organized 

modern group Centrarchidae (Micropteridae). 

The perchlike fishes are not found in American 

Cretaceous strata, and it. is a question whether 

they may not have evoh:ed in fresh water and 

later taken to the sea. At any rate, it must be 

said that so far as we know at present the Tertiary fishes mark a considerable advance on or at 

least change from their Cretaceous predecesSOJ'S. It ought to be possible as a rule to distinguish a Cretaceous from a Tertiary deposit 

by means of a single well-preserved fish scale. 

The exceptions will be found in those groups 

1 A possible exception is U. S. Geological Survey locality 6603, in the 

Uinta Basin, Vtah, which con~ains plant remains. Two poorly pre· 

served scales are figured in Plate X~XVI, figures 16 and 17. 
170 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

which range with little change from the·Creta- 1 Europe and America, and in America between 

ceous to the present day-the berycoids, clu- the faunas of the Atlantic seaboard, the.inland 

peids, or hemiramphids. In such groups only sea, and the Pacific coast. All these regions 

the recognition of the species and its identifi- of course h!:td types in common, and these 

cation with one .from beds of known age could appear to have been, at least principally, 

be of any service. Such a scale as that of pelagic or ope!l-sea organisms, such as UintaPomolobus? chicoensis, from the Chico, might crinus among. the echinoderms and various 

belong anywhere from that time to the present sharks among the fishes. There were, howday. So, also, with Flemilampronites hesperius, everf many differences. Scales of fishes from 

from the Fox Hills. the Chico, cut off from the inland sea by the 

Just as the Tertiary fishes mark an advance western uplands, are all different·from those in 

on the. Mesozoic, so also the later C:r;etaceous Rocky Mountain deposits. The Chico has a 

fishes present evidence of evolution and mod'- veritable clupeid, but so far no genuine clupeids 

ernization. ·This statement applies not only to have been found in the Benton, Niobrara, 

the Upper as contrasted with the Lower Creta:- Pierre, or Fox Hills. The inland waters seem 

.ceous, but also, and rather markedly, to the to have lacked berycoids, which are ~o charac-· 

Montana group as contrasted with the Colo- teristic of the Eur.opean strata. Comparisons. 

rado group. The scanty materials from the between the Old World ·and the· New World 

Fox Hills and Pierre now available already in- faunas are hindered by th,e difference in age of' 

dicate the beginnings of modern groups which some of the abundantly fossiliferous deposits. 

are absent from the older beds, and unq ues- Not only do the highly differentiated faunas of 

tionably later discoveries will emphasize the Hakel and Sahel-Alma in Syria (Mount. 

distinctions observed. Thus· we seem to find Lebanon) differ greatly from one another, but. 

evidence of a rather slow and gradual n1odern- only about 10 per cent of their genera are 

ization of the fish fauna, the breaks in the series common to the American Cretaceous. They 

corresponding with the geologic breaks and not must be referred to a later horizon than our· 

being attributable to any extraordinary migra- Cretaceous fishes. · The Cretaceous of Westtions or sudden new developments. phalia has more in common with the Syrian. 

There were, however, certain environmental deposits than with the English chalk and 

conditions which must have affected the rate of should be intermediate in age between these. 

evolution. and diversification. The inland seas two. Nearly half the· genera of the English. 

of the American Paleozoic were drained by the chalk are represented in the Kansas Niobrara,. 

Permian uplift, but during later Mesozoic time though perhaps the chalk is for the most part. 

this country once more possessed a vast med- somewhat older. I have prepared more elabiterranean sea, comparatively. shallow and orate statistics, but owing to the uncertain 

warn1, which reached its maximum depth prob- standing o'f a good ·many of the species they· 

ably during the Niobrara epoch. A modern are not as valuable as they look on· paper. 

map of North America marked in some way to The tendency of future investigations ·will. 

indicate the shallow-water areas, even down to doubtless be to emphasize the differences in 

100 fathoms,. will show how restricted is the the faunas, especially as studies of scales are. 

~istribution of the present littoral and shallow- likely to reveal many of the smaller and more. 

water faunas. They exist, as it were, in broad sedentary fishes. 

-rivers running mainly north ap.d south. They Prof. J. Henderson, who has paid much at-.. 

are circumscribed by climate, by land, and by tention to the Upper Cretaceous Mollusca, 

the open sea. In comparison the great. Creta- informs me that in his experience all the species. 

ceous inland sea must have afforded an amazing of the Benton differ from those of the Niobrara, 

wealth of opportunity for multiplication and and all those of the Niobrara from those of the. 

development, which may w~ll have been the Pierre. The Pierre and Fox Hills, on the other 

decisive factor in the evolution of many gr~nips hand, present faunas grading one into the. 

of 1narine organisms. other. As this did not wholly agree with some. 

In .this connection it is interesting, to inq':lire of the published records, I asked Mr. T. W. 

whether there were radical differences between j Stanton for his opinion. He replies that he is. 

the supposedly qontemporaneou~ faunas of in perfect accord· with Prof. Henderson. The, 
SOME AMERICAN CR:ETACEOUS FISH SCALES. 171 

Colorado and Montana faunas had few if any 

identical species of Mollusca, though of course 

n1any genera occurred in both. Old records 

contrary to these opinions ·were based on 

errors. Thus Inoceramus labiatus, supposed to 

occur in the Niobrara of Kansas and Nebraska, 

was Teally from the Greenhorn limestone, well 

down in the Benton. We have, then, in the 

Upper Cretaceous two extremely marked 

faunal breaks. They must represent long 

periods, during which many things happened,. 

Where no species of Mollusca persisted, surely 

no fishes could be expected to remain unaltered. 

Present information tends to confirm this 

opinion, and when a Benton fauna is found in 

beds ascribed to the Niobrara (see under 

Ilolcolepis pulchellus, p. 174) it is evident that 

there was an error in stratigraphy. 

BENTON SHALE. 

The previously recorded teleosts from the 

Benton are few, as follows: 

Apsopelix. A genus not known from later rocks. Mr. 

Stanton informs me that Cope's locality (in Kansas) is 

certainly Benton. · 

Pelecorapis varius Cope. Mr. Stanton says almost certu.in~y from the Benton; the Inoceramus referred to by 

Cope is presumably I. labiatus. Mr. Stanton adds, however, that if the Sibley referred to is the one now on the 

map there is some mistake, as this would place the 

locality in the Carboniferous. 

Protosphyraena bentoniana Stewart. 

H.'IJPBOdon lowii (Stewart). This and the last belong to · 

genera common to the Niobrara and Pierre. 

There itl also a very dubious record of Anogmius. To these are added in the present paper 

the following species: 

Holcolepis pulchellus 1 n. sp. 

Holcolepis delicatus n. sp. 

Holcolepis transversus n. sp. 

Holcolepis obliquus n. sp. 

Hypsodon? granulosus n. sp. 

Ichthyoclectes sp. 

Leucichthyops vagans n. sp. 

Erythrinolepis mowriensis n. sp. 

Halecodon clenticulatus n. sp. 

Cimolichthys sp. 

It is not at present certain that levelc:; in the 

Ben ton can be distinguished by n1eans of the 

fishes. Materials ascribed to the Aspen (for 

exmnple, U. S. G. S. localities 4874, 3870) present a Mowry fauna, as they should, for the 

Aspen and Mowry are approximately equivalent. 

t Tho rocks yielding this species wero referred to tho Niobrara by 

Bookly (U.S. Geol. Survey Bull. 596, pp. 40, 41, 1915), but the locality is 

in a faulted area· and may well boon a Benton outcrop. 

NIOBRARA FORMATION. 

The recorded fish fauna· of the Niobrara is 

very rich, comprising 23 genera, mostly f~und 

in Kansas. Several of these are discussed 

below, but I have no new species to add. 

MONTANA GROUP. 

The Montana· group includes the Pierre shale 

and .Fox I-Iills sandstone. The fishes are not 

sufficiently well known to throw any particular 

light on the divisions of the group. The following new forms, the last three of which are from 

the .Fox I-Iills sandstone, are described in this 

paper: 

Petalolepis? fibrillatus n. sp. 

Cycloides? incertus n. sp. 

Hypsoclon? radiatulus n. sp. 

Echidnocephalus? americanus n. sp. 

Helmintholepis yermiculatus n. sp. 

Cyclolepis stenoclinus n. sp. 

. Hemilampronites hesperius n. sp. 

According to previous records about half a 

dozen Niobrara genera (Ilyposodon, Syllaemus, 

Protosphyraena, Ichthyodectes, Empo or Oimolichthys, and perhaps Pa.chyrhizodus) survived 

to the Pierre; but not one of these is recorded 

from the Fox 1-Iills. This means little, perhaps, as hardly anything has been known of the 

Fox I-Iills fishes. 

CHICO GROUP. 

The following species from the Moreno formation of th~ Chico group of California are 

described below: 

Chicolepis punctatus n. sp. 

Pomolobus? chicoensis n. sp. 

Erythrinolepis chicoensis n. sp. 

Echiclnocephalus? pacificus n. sp. 

DESCRIPTION AND SYSTEMATIC DISCUSSION OF 

SPECIES. 

PISCES. · 

Subclass CHONDROSTEI. 

Family ACIPENSERIDAE. 

Scutes of Acipenser (A. toliapicus Woodward) 

are known from the London clay (lower Eocene) 

of the Isle of Sheppey. The plates named A. 

cretaceus Daimeries, from the Senonian of 

Belgium, are said by Woodward to belong 

apparently to some fish related to Dercetis or 

Eurypholis, and therefore are not chondrostean 

at all. In the Belly River formation (Upper 
172 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

Cretaceous) of Red Deer River, Alberta, 

Lambe found a scute which he called Acipenser 

albertensis. In the same deposit he found part 

of an elongated snout which bore a series of 

teeth, much like that of the more ancient 

Saurorhynchus (Belonorhynchus). This he 

named Diphyodus longirostris, but he did not 

attempt to indicate its affinities. It was afterward stated by Hatcher 1 that remains similar 

to both these fossils were common in the Judith. 

River and Lance formations in certain localities 

in Montana and Wyoming. The associated 

fossils indicated fresh-water conditions, so the 

absence of such remains from the Upper Cretaceous marine beds ·is not surprising. The 

question naturally arises whether by any possibility the Acipenser, so called, was in fact a 

toothed sturgeon, Diphyodus representing the 

jaw of the · same fish. The Saurorhynchidae 

seem not to have survived to the Cretaceous 

(Stenoprotome Hay, from Syria, being a very 

dubious representative), but it is possible that 

toothed sturgeons more or less intermediate 

between the Saurorhynchidae and Acipenseridae existed in that period. 

Subclass TELEOSTEI. 

Order HALECOMORPHI. 

Family PROTOSPHYRAENIDAE. 

Protosphyraena Leidy (Erisichthe Cope) IS 

abundantly represented in the Niobrara of. 

Kansas and has one species each in the Benton 

and Pierre. It is known mainly by the rostra 

and pectoral fins, a:q.d there is in the descriptions no mention of scales. Hypsocormus, considered to be related .to it, has smooth scales, 

small and deeply imbricating. 

Order ISOSPONDYLI. 

Family ALBULIDAE. 

I have supposed that the Albulidae (Albula 

and Dixonina) were the only fishes above the 

I-Ialecomorphi that had longitudinal basal 

circuli or fibrillae. 2 I find, however, that this 

peculiarity is shared by Alepocephalus agassizi 

(Alepocephalidae). Benthosphyraena macroptera, also referred to the Alepocephalidae, has 

small round scales wholly unlike those of Alepocephalus. The Alepocephalus scales, although 

having longitudinal ba.sal fibrillae, are in other 

respects entirely different from those of the 

1 U. S. Geol. Survey Bull. 257, p. 69, 1905. 

2 U. s. Bur. Fish·eries Bull., vol. 32, p. 122, fig. 2, 1912. 

Elopidae, being shaped much like the sole of 

the foot, the nucleus subapical, with coarse concentric circuli above it, the lower margin 

broader and thin, neither crenulated not with 

radii. The albulid scale, on the other hand, is 

subquadrate, with broad crenate lower margin 

and a few distinct basal radii. The albulid 

fibrillae are tuberculate, as in the Dipneusti; 

this ia not true of Alepocephalus. 

In view of their primitive characters, the Albulidae must have existed in the Cretaceous. 

The recorded species which have been assigned 

to this family, however, do not appear to belong there. Prochanos is to be referred to 

Chanidae. lstieus goes in Pterothrissidae. 

Ancylostylos from Croatia may be referred to a 

distinct family, of which it is the typical genus. 

Anogmius Cope (Syntegmodus Loomis), from 

the Niobrara of Kansas, may go in Pterothrissidae, but not in Albulidae or Osteoglossidae, to 

which it has been referred. Plethod1.ts forms n 

family, Plethodontidae, to which Hay also 

refers Anogmius. Apsopelix, to judge from 

Cope's description of the scales, seema to have 

some resemblance to the Albulidae, where it is 

provisionally placed by Hay. Cope states that 

the circuli are vertical, except in the region of 

the nucleus. The position of this genus must 

for the present remain undecided. Finally, 

Petalolepis divaricat1.ts (Geinitz), based on a 

scale from tb e Turonian of Saxony, appears to 

be a genuine albulid. An American scale. IS 

provi.~ionally referred to the same genu3. 

Genus PETALOLEPIS Steinla. 

Petalolepis? fibrillatus Cockerell, n. sp. 

Plate XXXI, figure 1. 

Scale 8.5 millimeters in diameter, subquadrate, but with obtusely rounded angles, a very 

little longer than broad; lines of growth evident, concentric, but the very fine fibrillae 

strictly longitudinal from one end to the other, 

except that toward the basal margin they curve 

inward, becoming more or leBs transverse, following the wavy outline of the· margin; the 

fibrillae are not tu berculate or beaded, as they 

are in Albnla; as in Petalolepis· divaricatus, on 

each side of the middle line in the basal region 

the fibrillae become curved and end by meeting 

each other at a very acute angle; there is a 

strong median plica on the basal half of the 

scale, but no ordinary radii, an~ this agrees 

with P. divaricatus. 
SOME AMERICAN CRETACEOUS FISH SCALES. 173 

U. S. G. S. locality 5094. Cretaceoud, Mesa 

Verde formation, 14 miles north of Rock 

Springs, Wyo., a little east of center of sec. 26, 

T. 21 N., R. 104 W. (Collected by V. H. 

Barnett.) 

A similar but much larger scale may represent a related species, but the surface as preserved presents a very fme irregular reticulation, with concentric lines of growth, and it can 

not be determined whether the fibrillae are 

longitudinal. So far as the visible characters 

go, this agrees with Winkler's problematic. 

Oycloicles, and it ma~v provisionally stand as 

described below. 

Cycloides? incertus Cockerell, n. sp. 

Plate XXXI, figure 2. 

Scale 16 millimeters in diameter (G. incisus 

Winlder is 17.5 millimeters in diameter), subquadrate; apical margin broadly rounded, 

apparently a little crimped; laterobasal angles 

obtuse but distinct; a very strong median 

plica on the basal three-fourths, the growth 

lines turned upward on approaching it, as in 

Winlder's figure. 

U. S. G. S. locality 5177. Cretaceous, Mesaverde :formation, about 5 miles southwest of 

Sycamore, Wyo., in the NE. i sec. 12, T. 19 

N., R. 103 W., ill the Rock Springs region. 

(Collected by V. H. Barnett.) 

In the general form and median plica this 

scale is suggestive of that of Mugil curema. 

The same sort of plica and basal margin may 

be seen in scales of the cyprinid Girrhina 

jullieni. There is also a conspicuous median 

basal plica in Ghanos, but it is broad and 

shallow, not forming a line. 

Family LEPTOLEPIDAE. 

A family found in the Cretaceous of Europe, 

surviving from the older Mesozoic. ''Scales 

thin, cycloidal, and deeply imbricating, usually 

ganoid in their exposed portion; lateral line 

not observable." (A. S. Woodward.) 

Fami~y ELOPIDAE. 

Genus HOLCOLEPIS Von der Marek. 

This genus was called Rhabdolepis by Von 

der Marek in 1863, but Troschel had earlier 

(1857) used that name for a palaeoniscid fish. 

Ilolcole1Jis was proposed in 1868. Agassiz, 

who hnd proposed the name Osmeroides for nn 

entirely different fish, unfortunately trans282880--19----12 

ferred it in 1844 to a species of Holcolepis; and 

in this he has been followed by several authors. 

The genus Holcolepis is certainly to be referred 

to the Elopidae, even after the removal of such 

genera as Pachyrhizodus, which A. S. Woodward places in. that family. The teeth are 

minute, entirely different from those of Pachyrhizodus. The dorsal fin is less modified than in 

modern Elopidae. Holcolepis has not hitherto 

been reported from the North American Cretaceous, our nearest form being Spaniodon 

simus Cope, a form with smooth scales. 

A. S. Woodward 1 described the scales of 

Holcolepis as "often ornamented in their exposed portion with delicate radiating lines of 

minute tubercles, marked in their covered portion with a few radiating grooves terminating 

in notches at the anterior truncated margin; 

hinder margin riot serrated; course of lateral 

line indicated by a feeble ridge and a notch in 

the hinder border of most of the scales" -that 

is to say, the scales have basal radii; but in a 

later publication 2 Woodward shows a scale of 

Osmeroides lewesiensis ( = Holcolepis lewesiensis) without any such radii. 

Osmeroides divaricatus Geinitz, 1868, is 

based on the scales of an albulid fish, and 

takng up the name Petalolepis Steinla, published by Geinitz as a synonym, the species 

becomes P etalolepis divaricatus. 

Osmeroides Zewesiensis (Mantell) as determined by Geinitz from the Turonian of Saxony 

consists of a mixture of different things, none 

of them identical with the English fish. One, 

the most recognizable, is similar to the living 

genus Pterothrissus in the character of its 

scales. This form 3 unfortunately takes the 

cumbersome name Kymatopetalolepis of Steinla 

and may stand as K. geinitzi n. sp. It has 

four to six fanlike basal radii, the circuli between them broken into dots. The nucleus 

is subapical, and the apical region hyaline. 

Osmeroides divaricatus Geinitz as figured by 

Fritsch 4 is wholly unlike the Geinitz species, 

having transverse basal circuli. There are 

three basal radii, and the basal margin is scalloped. 

1 Catalogue of fossil fishes in the British Museum, pt. 4, p. 11, 1901. 

2 The fossil fishes of the English chalk, pl. 23, fig. 8, 1907. 

a Geinitz, H. B., Die Fossilen Fischschuppen aus dem Plii.nerkalke in 

Strehlen: Gesell. Natur-u. Heilkunde Dresden Donkschr., 1868, pl. 2, 

figs. 1o-12. 

• Fritsch, Anton, Die Reptilian und_Fischo der bOhmischen Kreideformation, fig. 58, 1878. 
174 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

0. lewesiensis (Mantell) of Fritsch is also 

wrongly named. It is a scale with subapical 

nucleus and five strong basal radii, the basal 

margin very strongly scalloped. The scale 

has a strong resemblance to that of Megalops 

cyprinoides, and rna y therefore represent a 

fossil elopid of some unkll.own genus. 

Osmeroides belgicus Winkler, 1874, is based 

on a scale apparently congeneric with the socalled lewesiensis of Fritsch but considerably 

broader and with more basal radii. It is a 

large soale~ the transverse diameter being 15 

millimeters. 

The type of Holcolepis, H. cretaceus Von der 

Marek, is imperfectly known, and it is possible that the various speCies supposed to be 

congeneric could be divided into two genera 

with better materials. For the present I 

assume that the scale of H. lewesiensis, well 

figured by Woodward, is typical of the genus. 

Its most characteristic feature is the pseudoctenoid e;x:posed area, ornamented with radiating lines of pustuliform markings, derived 

from the circuli. H. latifrons (Woodward), 

from the chalk of Kent; is similarly orn~mented, 

but the lines are more broken up, producing, 

except near the margin, a pitted or malleate 

effect. The lateral line is very distinct. In 

H. levis (Woodward), from the chalk of Kent 

and Sussex, the scales possess "fine radiating 

ornament" and have distinct basal radii. 

They are therefore similar to those of the 

modern Elops, and the fish may not be congeneric with the others. 

The modern Elopidae (Elops, Tarpon, Megalops) have very distinct basal radii, 3 in Tarpon, 

about 5 to 7 in Megalops, and 12 to 18 in Elops. 

The basal margin is very strongly crenate in 

Megalops, ·moderately in Tarpon, but feebly 

in Elops. In Tarpon the apical field- has a 

radiating sculpture of minute tubercule-like 

elements, not clearly visible on casual inspection. This is the I-Iolcolepis sculpture, but 

very much finer and less conspicuous. In 

Megalops the region above the nucleus shows 

granulations but not distinct radial line_s; 

there is some approach to the condition of 

Holcolepis latifrons. _ Elops, above the nucleus, 

shows coarse transverse wrinkled lines, but the 

broad apical field is free from markings derived 

fro~ -the circuli and presents a num her of 

parallel radii. Appa~ently, then·, the early 

elopids (Holcolepis) had the exposed part of 

'the scale prominently sculptured with lines or 

rows of tubercles derived from the circuli, 

while the covered part was either withollt 

evident sculpture, except the fine circuli, or 

had a few distinct radii. The development 

has been toward the loss of the apical sculpture and the strengthening and increase in 

number of the basal radii. It see1ns that these 

changes were in process or even perfected as 

early as the Cretaceous, but typical Holcolepis, 

·as here understood, included the more· primitive type. Pachyrhizodus, to judge from the 

figure of a scale of P. subulidens (Owen)· published by Woodward (reproduced in Pl. XXXII, 

fig·. 3), had scales of the 1-Iolcolepis type, with 

strong or coarse sculpture on the exposed portion, and the base rounded and without radii. 

The scale was parallel-sided, and longer than. 

broad, the reverse being true of typical Holcolepis. Thus, though we may well place Pachyrhizodus in a distinct family, it may have had 

a common ancestor with the elopids, possessing 

the Holcolepis-like scale. 

In the American Cretaceous fauna the 

species described below; based on scales, are 

referred to Holcolepis, as· understood in a 

rather broad sense. Outside of the Elopidae 

the scales show a certain general resemblance 

to those of· Aulopus (Aulopidae), but in that 

genus the margin is strongly dentate. 

I 

Holcolepis pulchellus Cockerell, n. sp. 

~iate XXXI, figures 3, 4. 

Scale 7 millimeters in diameter, approximately 

circular, the apical margin obtusely angulate 

in the middle; nucleus only a little above the 

middle; lower margin not at all crenate; six or 

seven basal radii very feebly indicated, not 

distinctly developed, not definitely eut.ting the 

circuli; apical field with very numerous parallel raised lines, but toward the nucleus with 

·wavy lines as in E'lops. 

One mile south of the _Boetcher ranch, in the 

NE. i SW. t sec. 32, T. 10 N., R. 81 W., North 

Park, Colo. (Collected by A. L. Beekly and 

IIa.rvey Ba.ssler.) This is Beekly's locality 37.1 

It is referred to the Niobra.ra, but the seales 

from this ·a.nd several other localities referred by 

Beekly to the Niobrara resemble those from. the 

Mowry and · are therefore believed to have 

come from the Benton shale. All the localities 

1 Beekly, A. L., U. S. Geol. Survey Bull. 596, p. 42, 1915. 
SOME AMERICAN CRETACEOUS FISH SCALES. 175 

thus under suspicion failed to yield any characteristic Niobrara l\1ollusca, and the collection 

from Beeldy's locality 50, which did include 

Ostrea congesta Conrad, offered no such scales, 

·hut only one of lchthyodectes, the so-called 

'' Oladocyclus.'' c 

H. pulchellus was also found on the northwest shore of Lake Jolm, in theSE. i SW. i sec. 

34, T. 10 N., R. 81 W., North Park, Colo., 

by Beekly and Bassler. This is Beekly·'s 

locality 35. 

Holcolepis delicatus Cockerell, n. sp. 

U.S. G. S.locality6713. Cretaceous, Mowry 

shale, southeast of camp at old ehimney, Sisters 

.Hill, Buffalo, Wyo. (Collected by 0. B. Hopkins.) Seale 9 millim.eters long and 11 millim.eters wide; another scale 7 millimeters wide. 

The two following specimens are about ns 

broad as long and probably came from the 

vjcinity of the caudal peduncle. 

U.S. G. S. locality 4421. Mowry shale, Casper region, sec. 29, T. 33 N., R. 74 W. sixth 

principal meridian, Wyoming. (Collected by E. 

W. Shaw.) Scale 12.5 millimeters in diameter. 

U. S. G. S. locality 3417. Lower (Benton) 

Plate XXXI, figure 5. · part of Mancos . shale, Steamboat Springs, 

Seale 10 millimeters in diameter, subcircular; Routt County, Colo., on ridge near mineral 

simila.r to H. pulchellus, but apical margin springs, just west of town and south of Yampa 

rounded, nucleus a little below the middle; River. (OollecteJ. July 13, 1905, by T. W. 

lines of exposed area fi~er and denser, with more Stftnton and H. s~ Gale.) 

or less evident pits between; only vague indis- Flolcole1Jis transversu8 is closely related to H. 

tinct suggestions of basal radii. steinlai'(Geinitz), published by Geinitz as AeroBig I-Iorn Basin, in the SE. l SE. l sec. 15, · grammatolepis steinlai, the figw·e upside down. 

T. 43 N., R. 94 W., Wyoming. Near base of The H. steinlai scaleis 7 by 6 n1illimeters and 

Mowry shale. (Collected by C. T. Lupton.) has the nucleus apparently more basally placed 

H. c k 11 than in H. transvers·us. It is from the Turonian olcolepis transversus oc ere , n. sp. of Saxony and may very likely be identical 

Plate XXXI, figures 6- 13· with the English H. lewesiensi$ (Mantell), from 

Scales subquad.rttte, on sides nearly twice as beds of about the same age. 

broad. ns long, on other parts often narrow, 

varying to about as broad as long; laterobasal 

angles commonly rather prominent; apical 

margin broad, flattened or depre~:;sed in middle, 

not angular; no basal radii, but often a single 

n1edia.n fold, rather indistinct; apieal modified 

patch V-shaped, ornn,mented with a series of 

closely set interrupted ridges, without pits between; circuli :fine: the lateral ones directed upWtLrd, 1neeting t.he margin at a Yery acute angle; 

nudeus approximately central. 

Type a scale 9 millimeters in diameter, from 

U. S. G. S. locality 6682, ShLte Creek, l\1ount 

Leidy qu~tdrangle, Wyo. (Collected by Eliot 

Blach\velder.) Mollusks of this locality are 

Sftid to he not charaeteristic and may belong 

either in the Montana group OJ;' the upper part 

of the Colorado group, but the fish scales indicate Colorado (Benton) age. Other seales in 

the sa·me lot, referred to this species, are 11 

millin1eters and 14 millimeters in diameter. 

I also refer to this species the following: 

1J. S. G. S. locality 6681. Cretaceous, probably Aspen, Slate Creek, Mount Leidy quadrangle, Wyo. (Collected by Eliot Blackwelder.) Scale 10.5 millimeters 'in diameter. 

. . ~ . Holcolepis obliquus Cockerell, n. sp. 

Plate XXXII, figure 1. 

Scales 10 millimeters in diameter, much 

broader than long, without any trace of basal 

radii. Similar in most respects to H. transversus, but remarkable for the brevity of the 

elements in the apical patch and for the lateral 

circuli being oblique, at the middle of the side 

reaching the margin at an angle of about 45°, 

and above this becoming alrriost transverse. 

. Type collected with H. transversus, in Mowry 

shale at U. S. G. S. locality 4421. Details. are 

given above. 

Holcolepis? mandible. 

Plate XXXII, figure 2. 

In confirmation of th~ existence of a typically 

elopid type of fishes in· the North 'American 

Cretaceous, I give a figure of a mandibular 

ramus which seems to belong to Holcolepis or 

a closely related genus. It differs from that of 

H. lewesiensis in the straight (not. concave) 

descending upper margin of the dentary, and in 

this respect more resembles the modern Elops. 
176 SHORTER CONT'RIBUTIONS TO GENERAL GEOLOGY, 1918. 

It was collected by A. C. Veatch in the 

NW. l SW. l sec. 8, T. 19 N., R. 79 W., 

Carbon County, Wyo., and is ascribed to the 

Colorado .group. From the associated scales, 

which include an imperfect specimen of HolcoZepis, either pulchellus or a closely related 

species, I infer that the material is from 

the Benton. The mandible and the IIolcolepis 

scale probably belong to the same species. 

Genus RHACO:tEPIS Agassiz. 

Dr. D. S. Jordan has kindly sent me material 

of Rhacolepis buccalis Agassiz, from the Cretaceous of Ceara, Brazil. The scales are broad, 

with coarse, rather widely spaced circuli, transverse above and below the nucleus, and many 

of them broken or anastomosing above the nucleus. The apical margin is delicately plicate, 

with a series of parallel ridges, very much as 

in Otenothrissa. This marking probably corresponds with the system of apical radii of 

Elops and h~s nothing to do with the pseudoctenoid sculpture, derived from the circuli, of 

IIolcolepis. Rhacolepis is therefore entirely 

distinct from Holcolepis, and the scales can 

not be confused. It is just possible that the 

Pachyrhizodus scale, which seems from Woodward's figure (reproduced in Pl. XXXII, :fig. 

3) to be of the same general type as that of 

Holcolepis, is really constructed in the manner 

of Rhacolepis, but with the shape entirely 

different and the apical plicae much longer. 

Genus NOTELOPS Woodward. 

In the Brazilian Cretaceous Notelops brama 

(Agassiz), also received from Dr. Jordan, the 

circuli are :finer and denser than in Rhacolepis. 

I can not make out any ''delicate radiating 

ridges," mentioned by Woodward, but the 

material is not very good. Jordan and Branner 1 state that the scales are cycloid and 

entire. They are, in any event, wholly distinct from those of Rhacolepis. 

Genus HELMINTHOLEPIS Cockerell, n. gen. 

Scale· cycloid, circular, or slightly longer 

than wide, about 17 millimeters across in the 

type; nucleus a little below the middle; circuli :fine, concentric on basal half but longitudinal and very wavy, like minute worms, on 

apical half; the apical marginal area delicately· longitudinally striate, with about :five 

1 Smithsonian Misc. Coil., vol. 52, p. 9, 1908. 

circuli between each pair of strire or fine radii. 

This may not be elopid, but I do not know 

where better to refer it. The striate margin 

is like that of Hypsodon, but there are no 

tubercles, and the microscopic structure is 

very different. There "are no radii in the basal 

field, and the lower margin is broadly rounded. 

Type H. vermiculatus. 

Helrnintholepis verrniculatus Cockerell, n. sp. 

Plate XXXII, figure 4. 

Diameter about 17 millimeters. 

U. S. G. S. locality 9184, Cretaceous, Fox 

Hills sandstone, north side of Thompson 

River, near top of ridge about 11 miles northeast of Milliken, sec. 1, T. 4 N., R. 67 W., 

Greeley quadrangle, Colo. (Collected by T. E. 

Williard.) The type scale partly overlaps a 

scale of Hemilampronites hesperius. 

Family PTEROTHRISSIDAE. 

The interesting fan1ily Pterothrissidae is 

represented to-day by Pterothrissus Hilgendorf 

(Bathythrissa Guenther) from deep water off 

Japan. It is related to the albulids, but the 

scales have the circuli of the median and basal 

regions (a large inverted V -shaped area) broken 

up into dots and fine rugae. In the Cretaceous 

rocks of Westphalia and Syria the family is 

represented by the genus Istieus, the scales of 

which are said to be elliptical, not pectinated 

(A. S. Woodward). Anogmius, from the Niobrara of Kansas, seems to be more or less 

related. Kymatopetalolepis geinitzi Cockerell, 

based on scales from the Turonian of Saxony, 

appears to be· typically pterothrissid. Ohicolepis, a new genus from the Chico, may also be 

referred to this family. 

Genus CHICOLEPIS Cockerell, n. gen. 

Scales broad, subquadrate, shaped as in 

Pterothrissus, with very broadly rounded apical 

margin; nucleus apical, very near the margin; 

sides with dense simple longitudinal circuli, 

passing vertically up to the apical margin; the 

whole area inclosed by lines drawn from the 

middle of the apex to the laterobasal corners is 

covered with minute punctiform dots, the circuli having combined to form an extremely 

dense honeycomb-like reticulation, the punctures round and often running more or less 

in transverse series. In the region of the 
SOl\fE AMERICAN CRETACEOUS FISH SCALES. 177' 

lateral circuli are· here and there streaks of 

·punctured surface. · No ordinary radii, but a 

median line or plica from base ·to apex, most 

conspicuous on basal half. This superficially 

resembles Petalolepis? jibrillatus, but its structure is very different. Type, f!~ punctatus. 

Chicolepis punctatus Cockerell, n. sp. 

Plate XXXIV, figure 1. 

Scale 16 millimeters in dimneter; laterobasal 

c~_rners rectangular. 

U. S. G. S. locality 7030. Cretaceous, Chico 

group, south side of Ortigalito Creek, Cal., in· 

Moreno formation. (Collected by Robert Anderson . .) For. further description of locality 

see Pomolobus chicoensis. The absence of the 

ordinary radii at once distinguishes this species 

from Pterothrissus and l{ymatopetalolepis. 

Family ICHTHYODECTIDAE. 

The fishes assigned to the Ichthyodectidae 

cannot be referred to Chirocentridae; the scales 

are radically and entirely different from those 

of the living Ohirocentrus, and·· the teeth are 

implanted in deep sockets. Stewart also seems 

fully justified 1n separating the Saurodontidae, 

especially on account of the remarkable unpaired predentary. 

Genus HYPSODON Agassiz. 

The type of Hypsodon is H. lewesiensis, but 

unfortunately Agassiz included under this 

name fishes that were not even congeneric. 

Cope, commenting on this fact, remarked that 

Hypsodon included some fishes with teeth of 

equal length and others in which they were 

unequal. He proposed to re3trict the name to 

the genus having equal teeth, and according 

to this decision Ilypsodon would take the place 

of the genus later named Pachyrhizodus by 

Dixon. I-Iowever, the specific name lewesiensis was adopted from Mantell, who had described the fish with unequal teeth as Megaloclon? lewesiensis. It is this fish which Agassiz 

figured in" Recherches sur les poissons fossiles," 

volun1e 5, Plate XXVa, figure 3, and Plate 

L~Vb,· figures 1-3. This appears to ·fix the 

type in a contrary sense to Cope's decision, and 

Hypsodon takes the place of Portheus Cope. 

Stewart suppressed Portheus in favor of 

~Y iphactinus Leidy, which was based on a 

pectoral fin spine of the same species as Cope's 

type of Portheus. Ilypsodon is much older, and 

the giant fish of the Niobrara rocks will take 

the name Hypsodon audax (Leidy). Portheus 

mantelli Newton, from· the English chalk, ·becomes Hypsodon lew~sirmsis· (Mantell}. In 

America the' genus is well' represented in the 

Niobrara and has one species, Hypsodon lowii 

(Portheus lowii Stewart), in the Benton.,· ... ,· 

The University of Kansas has rematMt1:>1y 

well preserved material of I-l. audax/ c· i~:hd 

through the kindness of Prof. S: J. Huntet I 

have received photographs of. the scales, ·which 

are reproduced here. 

HypsoJlon audax (Leidy) Cockerell. 

Plate XX~II, figure 8; Plate XXXIII, figures ~, 2. 

Xiphactinus audax Leidy, Acad. Nat. Sci. Philadelphia 

Proc., p. 12, 1870; U. S. Geol. Survey Terr. Rept., 

vol. 1, pp. 290, 348, pl. 17, figs. 9, 10, 1873. . 

Cope, U. S. Geol. Survey Terr. Rept., vol: 2, p. 276, 

1875. 

Hay, Zool. Bull., vol. 2, p. 27, 1898. 

Stewart, Kansas Univ. Quart., vol. 7, p: 115, 1898; 

idem; vol. 8, p. 107, 1899; Kansas Univ. Geol. Survey, vol. 6, p. 267, pis. 33-47, 1900. 

Saurocephalus audax (Leidy) Cope, Am. Philos. S~c. Proc.,. 

vol: 11, p. 553, 1870; U.S. Geol. Survey Terr. Ann. 

Rept. for 1870, p. 418, 1871. 

Portheus? audax (Leidy) Hay, U. S. Geol. Survey Bull. 

179, p. 384, 1902. ' 

Scales extremely broad, the width about 

twice the length, though on the caudal peduncle 

they are undoubtedly much narrower. Exposed area densely covered with small tubercles, 

which in the apical region are arranged in longitudinal series, being in fact situated on longitudinal ridges. The basal region has fine concentric lines of growth, and numerous more or 

less broken radii, spread out in broad fan 

shape. The Oladocyclus occidentalis of Leidy, 

which has page priority over X iphactinus 

audax, is based on just such scales, but whether 

of the species H. audax it is not at pr~sent possible to decide. Loomis thought the 0. occidentalis scales belonged to Ichthyodectes (or 

Gillicus) arcuatus Cope, and wrote lchthyo-· 

dectes occidentalis (Leidy) for that species .. 

This assignment certainly can not be maintained. It appears that the type locality of 

0. occidentalis is uncertain: On one page Leidy 

says that the material came from Nebraska; 

on another he says that it came· from Sage. 

Creek, Dakota. Leidy suggested that the, 

scales before him probably belonged to several 

species. 
178 SHORTER CONT'RIBUTIONS TO GENERAL GEOLOGY, 1918. 

The name Oladocyclus Agassiz was based on Typical H~ audax scales, about 50 milliscales from Brazil (0. gardneri Aga~siz), which· meters across, have been found in the Mancos· 

do not appear to be identical with. any of the shale 1! ~iles northeast of Columbine, Routt 

North American or European genera, thoi.1gh County, Colo. (Collected by Colorado Geo:. 

there is close similarity in the branching lateral logical Survey.) 

line canals. I have material of the Brazilian 

fish, kindly sent by Dr. D. S. Jordan. Woodward, in his ''Fossil fishes of the English 

chalk," abandons the use of Oladocyclus for 

European fishes, remarking that Agassiz referred to this genus scales of the 1chthyodectes 

type, calling them all Oladocyclus leivesiensis. 

The scales which Geinitz called Oladocyclus 

strehlensis were in the main of this same type. 

The question · which now arises is whether 

scales of Hypsodon can be clearly distinguished 

from those of 1chthyodectes. Woodward figures 

1chthyodectes scales, and they differ from those. 

of Hypsodon only in the strictly. entire basal 

radii. In 1chthyodectes, as I understand it, 

the bas~l part of the scale frequently splits 

along the radii, producing the appearance of 

a fr.ayed edge of ~epar~ted narrow bands. The 

Hypsodon lowii (Stewart) Cockerell. 

Plate XXXIy, figure 2. 

Portheus lowii Stewart, Kansas Univ. Quart., vol. 7, p. 

24, pl. 2, fig. 2, 1898. 

Hay, U. S. Geol. Survey Bull. 179, p. 384, 1902. 

Xiphactinus lowii (Stewart) Hay, Zool. Bull., vol. 2, p. 

27, 1898. . 

Stewart, Kansas UD.iv. Geol_. Survey, vol. 6, p. 293, 

pl. 48, fig. 2, 1900. 

U. S. G. S. ·locality 7294. Cretaceous, 

Benton, sec. 20, T. 9 N., R. 77 W., half a mile 

northwest of Kerr's ranch, North Park, Colo. 

(Collected by A. L. Beekly and Harvey Bassler.) 

A large scale, 32 millimeters across, provisionally referred to H. lowii, as it is exactly the 

sort of scale that species might be expected 

to have. · 

lateral line canal is branched, more or less Hypsodon? radiatulus Cockerell, n. sp. 

Y -like, or rarely in the complex manner of the Plate ~XXII, figures 6, 7. 

Brazilian Oladocyclus. A photograph of 

"Oladocyclus lewesiensis,"· received from Dr. Scale 15 millimeters across, with apical 

A. s. Woodward, shows the fraying-out effect ridges but apparently without the tubercles of 

very well and should represent 1chthyodectes. H. audax. Another scale, 15.5 millimeters 

The species of 1-Iypsodon and 1chthyodectes ·re- across, is of the same species but latinucleate 

corded from the Kansas Niobrara are riurrierous, (renovated). As this species comes from a 

and it will be difficult or impossible to connect later formation than the Niobrara, it is doubtthem all up with their scales. less distinct from the Kansas fishes described. 

A very fine scale, 40·millimeters long and 35 U.S. G. S. locality 5177. Cretaceous, Mesa 

millimeters broad, comes from the Niobrara of Verde, about 5 miles southwest of Sycamore, 

New Me:x,ico (U.S. G. S.locality 8354, Meloche Wyo:, in the NE. ! SE. l sec. 12, T. 19 .N., 

ranch, eastern edge of Raton quadrangle; ·col- R. 103 W., in the Rock Springs regi0.n. (Collected by W. T. Lee). It is not at &ll of the lected by V. H. Barnett.) Oycloicles? incertus 

same shape as the Kansas University 1-I. audax is from the same locality and horizon. 

scales, but it presumably comes from the caudal · U. S. G. S. locality 5174. Cretaceous, 'ftfesa 

region, and is similar to one of the scales Verde, about 2-! miles north of Sycamore,. Wyo., 

figured by. Leidy as Oladocyclus occidentalis. in theSE. l sec. 17, T. 20 N., R. 102 W. 

The striae in the apical region are very delicate, 

and the tubercles are between the ridges instead of upon them; but this is probably a 

reverse impression. In view of the large size 

and general ~greement in· characters this scale 

is referred to H. audax. 

A still larger 1-I.- audax scale comes from 

Wyoming. (10 miles southeast of Glenrock, in 

the SW. l NE. l sec. 29, T. 33 N., R. 74 W.; 

co~ected by V. H. Barnett); it is 51 millimeters 

across. 

Hypsodon? granulosus Cockerell, n. sp. 

Plate XXXII, figure 5. 

Scale nearly circular, slightly broader than 

long, about 21 millimeters in diameter, basal and 

apical margins rounded; circuli fine, concentric, except in large exposed area extending 

to the region of the nucleus in the center of the 

scale, where the surfu.ce is finely rugose, without 

the definite tubercles of H. a·uilax; apical margin lon~itudinally striate ·but not tuberculate; 
SOME AMERICAN CRETACEOUS FISH SCALES. 179 

bnse with about u. dozen imperfect and broken· 

radii. 

U.S. G. S.locality 4874. Cre.taceous, Mowry 

shale, 100 double paces south of the north 

quarter corner of sec. 19, T. 28 N., R. 91 W., 

near North R.awlins, Wyo. (Collected by 0. P. 

Hopkins.) . . 

It is possible that this species and II.? rad~at1tlus belong to elopid fishes, u.nd not to the Ichthyodectidae. With I-I.? granulosus occurred 

Leucichth?Jops vagans and Ilolcolepis trans·veTsus. 

Genus ICHTHYODECTES Cope. 

Plate XXX'IV, figures 3, 4. 

About eight species of lchthyvdectes u.re known 

from the Niobrarn of Kn,nsas. Three species 

occur in the chalk of England. The type 

species is I. ctenodon Cope from Kansas. At 

present we can do no more than recognize the 

o·enus fron the scales; it is doubtful whether b 

the scales exhibit specific eharacters. The two 

following ttre characteristic: 

U. S. G. S. locality 2402. Cretaeeous, lmver 

part of Colorado shale, creek north of Low9r 

Sherburne Lake, Swift Current Valley, tributary to St. :Marys River, ~1ont., latitude 48° 

n0-55', longitude 113° 25'·. (Collecte~ by 

Bn.iley Willis ttnd Stuart Weller.) Scale 6 

1nillimeters in dittmeter. 

U.S. G. S. locality 7277. Cretaceous, Niobrara, i.n the NE. l SE. l sec. 34, T. 7 N., 

R. 82. W., east of Cl~ver Valley telephone line, 

about 3 or 4 miles south of Butler, North Park, 

Colo., yellow sandy materiaL (A. L. Beekly.) 

This is Beekly's locality 59.1 Ostrea congest(~ 

oceurred in the smne ·materiul. 

Ichthyodectes scales also oecur in' Benton 

roek north of Boulder, Colo., where they were 

collected bv Prof. J. Henderson (Colorado 

Univ. ~1us." 459). One of these scales, 15 

millimeters in transverse diameter and about 

11 millimeters long, is fron1 the latern.lline and 

is remarkable for the con1plex, treelike system 

of branching canals, quite as complex as in the 

Brazilian Oladocyclus. This species tends to 

weaken our conviction that· lchthyodectes and 

Oladocycltts are really djfferent genera; but the 

scnles of Oladocycl'l.tS gardneri _differ in the basal 

1 U.S. Gool. Survey Bull. 596, p. 42, 1915. 

region from those of lchthyorlectes, and in view of 

the difference of loeality there is no great probability · that the fishes are really congeneric. 

:Moreover, as A. S. Woodward shows, 0. gardneri differs also from lchthyodectes in the more 

.anterior position of the dorsal fin. 

Ichthyodectes libanicus (Pictet and Humbert), 

from Syria, which I have examined in the 

American Museum of Natural History, has 

very broad scales, smooth and porcelain-like 

on their exposed parts. Woodward states that 

the species has the dentition of Ichthyodectes. 

Cretaceous fish scales from Turkestan. 

Plate XXXIV, figures 6-12. 

G. D. Romanowsky 1 has figured certain Cretaceous scales from Turkestan, and the figures 

are reproduced on Pla~e IV. 

Figures 6, 7, 8, referred by Romanowsky to 

Oladocyclus strehlensis Geinitz, agree with 

Ilypsodon. 

Figure 9, referred· to Osmeroides lewesiensis 

var., appears to be· immature Hypsodon, the 

scale probably from the subcaudal region. 

Figure 10, referred· to Oladocyclus strehlensis·, 

agrees with Ichthyodedes. 

Figure 11, called Osmeroides pectinolepi~ 

Romanowsky, is imperfect· and apparently 

latinucleate (regenerated); it may be Ichthyodectes. · 

Figure 12, called Beryx sp., can not be determined. It shows nothing to justify a reference to the genus Beryx. 

Family PLETHODONTIDAE. 

The scales of Plethodus are unkno'wn; the 

species are distinguished by the form of the 

dental plates. Anogmi.us ·Cope, well represented in the Niobrara of Kansas, is placed in. 

the Plethodontidae by Woodward and Hay. 

Its former reference to the Osteoglossidae was 

manifestly incorrect; no Cretaceous Osteoglossidae are known, nor are they likely to be 

found in marine strata. The scales of Anogmius polymicrodu~ 'Ste~art, as described by 

A. S. W oodwar<;l, are "moderately thick, showing only lines of growth; they appear to have 

been deeply overlapping." 

1 Materialui dlya geologii Tur.kestanskago kraya, pts. 2, 3, 1884, 

1890. 
180 SHORTER CONTRIBUTIONS TO 'GENERAL GEOLOGY, 1918. 

¥amily CLUPEIDAE. 

Genus POMOLOBUS Rafinesque. 

Pornolobus? chicoensis Cockerell, n. sp. 

Plate XXXIV, figure 5. 

Scales 4.2 millimeters broad, considerably 

broader than long, cycloid,· with the hyaline 

apical margin at most slightly crimped; covered portion with very fine strictly transverse 

circuli; a more or less distinct median longitudinal groove or fold on basal half; three transverse radii, the second and third interrupted in 

middle, the interval a little greater than half 

the length of either lateral division. 

U.S. G. S. locality 7030. Cretaceous, Chico 

group, south side of Ortigalito Creek, Cal., 1 

mile above the mouth of its canyon and 11 

miles northeast of Erreca's, in base of gully 

draining north along west line of the SW. i sec. 

28, T. 11 S., R. 10 E., and joining Ortigalito 

Creek near center of west line of section. In 

shale of Moreno formation, below the fossilof Syllaemus latifrons Cope, the type of the 

genus, and the circuli are not transverse, as in 

Clupeidae.2 

Family SALMONIDAE. 

Genus LEUCICHTHYOPS Cockerell, n. g~n. 

Scales sirriilar in type to those of the living 

Leucichthysnigripinnis (Gill); cycloid, the apical 

margin broadly rounded, the basal with a broad 

1nedian lobe, the margin ~ore or less cone ave 

between this and the rather prominent laterabasal angles;-· apical radii weak, about as in 

Le?.tcichthys)· no basal radii; circuli fine, concentric; growth lines very distinct, probably 

indicating that the fish was migratory. Scales 

from caudal region are narrower. Lateral line 

scales have a prominent canal, expanding 

basally. Type L. vagans. 

Leucichthyops vagans Co.ckerell, n. sp. 

Plate XXXIV, figure 13; Plate XXXV, figures 1-15. 

iferous conglomerate. (Collected by· Robert The type scale is from U. S. G. S. locality 

Anderson.) 7095 and has a diameter of 9 millin1eters. It 

This scale exactly agrees wi~h the living genus is distinctly broader than long. The exact 

Pomolobus, differing from. P. pseudoharengus locality js the NW. i SW. i sec. 20, T. 11 N., 

(Wilson), from Lake Ontario, only in the di- R. 79 W., 1 mile southwest of Dean's ranch, 

rectly transverse, not distinctly oblique broken North Park,. Colo. This is Beekly's locality 

radii. It is very likely that other parts of the 19, supposed to be Niobrara but to judge fro!fi 

fish would reveal generic distinctions, but per- ·the fishes apparently Benton. The following 

haps it is not impossible that Pomolobus dates are also referred to this species, although they 

from the Upper Cretaceous. It is a singular may represent more than one species, not 

thing that such a type should be found in the readily if at all separable on scale characters. 

California Chico but should wholly fail to ap- The scales differ greatly in shape, but only as 

pear (so,far as my material shows) in the strata might be expected on different parts of the fish. 

east of the Sierra Nevada, whereas to-day 1. Scales of the same general form as the 

Pomolobus and its close relative Alosa are found type. 

only in the north. Atlantic and (Alosa) Medi- Colorado group, in the NW. i SW. i sec. 

terranean. With reference to the antiquity of S, T. 19 N., -R. 79 W., Carbon County, Wyo . 

. the clupeid type, it may be noted that A. S. Scale 12.50 millimeters long and broad. Also 

·Woodward 1 describes a fish from the Lower second scale, incomplete. 

Cretaceous of Bahia, Brazil, as Scombroclupea 1j, S. G. S. locality 3880. Near base of 

scutata, and remarks that it does not differ :Mancos shale, 4 miles east of Meeker. Colo. 

much from Olupea itself. Typical Scombro- Scale 1 (millimeters in diameter. 

· clupea comes from the much later rocks of Graneros shale, Little Spring Creek, northMount Lebanon, in Syria,· and it is very prob- east corner of Sturgis quadrangle, Black Hills, 

able that the Brazilian fish, when better known, in reddish rock. In addition to normal scales 

will prove generically distinct. In the North .there is a large latinucieate (regenera:ted) one 

American Cretaceous we have recorded only 13 millimeters in diameter. 

one supposed clupeid type, Syllaemus Cope U. S. G. 8. locality 7275. Lower Benton, 

(Leptichthys Stewart). I have examined scales j north bank of Norris Creek about 200 yards 

1 London Geol. Soc. Quart. Jour., vol. 64, p. 360, 1908. 2 Zool. Anzeiger, Band 45, p. 190, 1914. 
SOME AMERJCAN CRETACEOUS FISH SCALES. 181 

north of Norris house, 12 to 14 miles south of 

Walden, in the NE. i SW. i sec. 13, T. 8 N., 

H.. 82 W., North Park, Colo. (Collected by 

A. L. Reeldy.) This is Beekly's locality 57.1 

A ln.rge scale, diametei· 14.5 mjllimeters. 

2'. Narrow scales. presurnably fron1 the 

caudal pedunele. 

U. S. G. S. locality 6681. Probably Aspen, 

Slate Creek, :Mount Leidy quadrangle, Wyo. 

(Collected by Eliot Blackwelder.) Scale about 

9 millimeters across, distinctly convex. II olcole7,Jis t'ra.ns'versus occurs at the same locality 

and horizon. 

U. S: G. S. locality 7110. Probably Benton, 

Beeldy's locality 37.2 Scale 8.2 millimeters 

across. H olcolepis JYu.Zchellus occurs at the 

sam.e localitv and horizon. 

U. S. G.w S. locality 8916. Mowry shale, 

Big I-IOI·n Basin, Wyo. (Collected by C. T. 

Lupton.) For extt.ct data see description of 

Holcolepis delicatus (p. 17 5), which occurred 

with it: The narrow Le'l.tcichthyops scale is 

accon1panied by others of the normal type. 

3 . .Broad, lateral line scn.les. 

U. S. G. S. locality 6682. Cretaceous, probably Colorado group, Slate Creek, Wyo. (Collected by Eliot Blackwelder.) Accompanied 

by a typical scale of the same species and by 

scales of ll olcolepis transversu.s. 

U. S. G. S. locality 7095. Probably Benton, 

in the NW. i SW. t sec. 20, T. 11 N., H.. 79 W., 

1 mile southwest of Dean's ranch, North Park, 

Colo. This is Beekly's locality 19., the type 

loculity of L. 1.;agans. Narrow scales also occur. 

There is also 11. scale of II olcolepis obliq_'IJ..US. 

U. S. G. S. locality 7100. In the NW. l 

SE. l sec. 8, T. 11 N., R. 81 W., northeast of 

the IIill ranch, North Park, Colo. Beekly's 

locality 26, 2 said to be Niobrara but probably 

Benton. (Collected by A. L. Beekly and 

G. J. Finlay.) The scale is 8 millimeters in 

diameter and is accompanied by a typical 

scale and one of Ilolcolepis. 

U. S. G. S. locality 7110. Beekly's locality 

37 (see above). 

The scales of Leucichthyops certainly appear 

to indicate a primitive salmonid fish; the bones 

were probably delicate and rarely preserved. 

The scales show a certain resemblance, however, to those of Thymallus, though in that 

• U. S. Oool. Survey Dull. 596, p. 38, 1915. 

~ ldom, p. 42. 

genus tb,e lateral line scales are much narrower 

and the median basal lobe is very large. It is, 

of course, possible that in the Cretaceous the 

Salmonidae and Th ymallidae were not differentiated. None of the European scales 

figured by Geinitz or Fritsch are of the Leucichthyops type. The scales of .A ulolepis typus 

Agassiz, as figured by Woodward/ are curiously similar to those of Leucichthyops but 

wholly lack the radii in the apical field. 

Genus CYCLOLEPIS Geinitz. 

The name Oyclolepis has been applied to 

subcircular or oval scales, with concentric 

circuli, nucleus central or subcentral, and all 

radii and ctenoid elements wholly ab'sent. 

This is, of course, the salmonid type of scale,. 

excellently typified by ·the living Stenodus 

maclcenziei, from Alaska. Oaranx scales are 

very similar but have the circuli more or less 

distinctly angular at the sides. The scale 

which Fritsch erroneously calls .Aspidolepis 

steinlai Geinitz, from the Cretaceous of Bohemia, has the shape and moderately eccentric 

nucleus exactly as in Stenodus. A difficulty 

in dealing with scales of this simple type is 

that uncharacteristic scales of qmte different 

fishes may closely simulate them, as shown by 

H. F. Taylor 4 in figures of essentially cycloid 

scales from the head of Oynoscion. Of course, 

the more characteristic scales of the same 

fishes would be almost sure to appear also in 

the deposits. 

Cyclolepis stenodinus Cockerell, n. sp. 

~ Plate XXXV, figure 16. 

Scale oval, its greater d!ameter 12 millimeters; nucleus central (not eccentric as in 

Stenodus); circuli simple and concentric; rather 

strong growth lines, indicating possible migratory habits. Another scale, doubtless of 

the same species, is practically circular. 

U. S. G. s.· locality 9190. Fox Hills sandstone, Greeley quadrangle, Colo. (Collected 

by T. E. Williard.) For details of the locality, 

see description of Iiemilampronites hesperius 

(p. 185), which was found with it. The mollusk Oallista nebrascensis Meek and ~ayden 

was in .the same material. 

a Woodward, A. S., The fossil fishes of the English chalk, pl. 19, 

figs. 3b, 4, 1903. . 

· • U. S. Bur. Fisheries Dull., vol. 34, pl. 52, 1914. 
182 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

Family ERYTHRINOLEPIDAE Cockerell, n. fam. 

Genus ERYTHRINOLEPIS Cockerell, n. gen. 

Scales rather small, subtriangular or subcircular, cycloid; basal margin slightly or not 

crenate; circuli normal and concentric on basal 

half but excessively fine on apical half; radii 

apical~ basal and lateral, but very irregular 

and often broken. The scales closely resemble 

those of the South American fresh-water 

Erythrininae but lack the coarse vertical circuli of the apical area. They may also be compared with the Old World Cyprinidae, and 

more remotely with the Mrican fresh-water 

genus Phractolaemus. They also show some 

resemblance to Pantodon.1 

While I was puzzling over the scales, I received a paper by Eastman 2 in which it is set 

forth that. the Cretaceous teeth of the genus 

Onchosaurus Gervais (Ischyrhiza Leidy; Gigan-· 

tichthys Dames) agree very closely with those 

of the living fresh-water Tlydrocyon and floplias, characoid genera. 3 It appeared to be a· 

confirmation of Eastman's results that fish 

scales so similar to those of the Erythrininae 

(Iloplias, Ilopl"erythrinus, and Erythrinus) 

should occur in the Mow-ry shale. I wondered 

whether the Mowry could be a fresh-water deposit; and this suspicion seemed to receive 

some confirmation in the collection from U. S. 

G. S. locality 6603, in the Uinta Basin, Utah, 

assigned to the Mowry and including poorly 

preserved remains of land plants. This lot, 

however, included no Erythrinolepis scales. 

Mr. Stanton informe~\ me that although Mollusca were rarely found in the Mowry, two 

localities on the southeastern border of the 

Big Horn Mountains had yielded ammonoids 

probably belonging to the genus jjfetoicoceras, 

and one of them yielded Inoceramus. These 

are clearly marine. One of these localities 

(4941) yielded also scales of Erythrinolepis, as 

well as those of Holcolepis. It must be said' 

that the Mowry shale contains scales belonging 

to genera ·also present in undoubtedly· marine 

1 Bioi. Bull., vol. 20, pl. 3, fig. 18, 1911. 

2 Eastman, C. R., Dentition of Hydrocyon and its supposed fossil allies: 

Am. Mus. Nat .. Hist. Bull., vol. 37, pp. 757-760, 1917. 

a Dr. G. A. Boulanger, of the British Museum, writes me that he has 

read Dr. Eastman's paper and thinks his identification of Onchosaurus 

with the Characinidae highly probable. He adds:' 'I shall be pleased if 

he is right, as I predicted the discovery of Upper Cretaceous characinids 

in 1905 (Rept. Brit. Assoc.)." I thought it possible that Phractola~m'us 

might be found to have similar teeth, but Dr. Boulanger informs me tbat, 

the teeth of this genus do not show the characteristic base of Onchosaurus 

and Ilydrocyon. 

Benton, and Erythrinolepis or a very closely 

related form occurs in the Chico. It· can not 

be held, consequently, that Erythrinolepis is a 

fresh-water genus. It is also out of the ques-

.tion to consider Erythri"nolepis to be the .scales 

of Onchosaurus, for the latter belongs to a very 

much later period. 

The apical field of the Erythrinolepis scale 

appears ·in most specimens to be without any 

circuli; but in one good example (locality 4941, 

Big Horn Mountains) radiating excessively 

fine apical circuli can be seen, about four or five 

to one of the basal field. Laterally these circuli· are nearly at right angles to the lateral 

ones, which are nearly vertical at this point. 

In the Erythrininae it is the apical series of circuli which is much coarser than the basal, and 

the lateral apical ones are continuous with the 

basal. We must suppose that Erythrinolepis 

represents a distinct family, Erythrinolepidae, 

though it can not be adequately defined. 

Erythrinolepis mowriensis Cockerell, n. sp. 

Plate XXXVI, figures 3-6. 

Scales obtusely subtriangular, the base 

gently convex; radii basal, apical and lateral, 

very irregular, and often incomplete. The 

type is about 5 millimeters in diameter. 

Type from U. S. G. S. locality 6713, southeast of camp at old chimney, Sisters I-Iill, Buffalo, Wyo., in Mowry shale. (Collected by 0. 

B. Hopkins.) Holcolepis transversus is from the 

same locality. , 

Some other collections contain this species, 

as follows: 

·u.S. G. S.locality 4896. North of Wolf Creek 

canyon, Big I-Iorn · Mountains, Wyo. (Collected by T. E. Williard.) Accompanied by 

Holcolepis and Leucichthyops. 

U. S. G. S. locality 4941. About 2! miles 

west of Klondike, Wyo. (Collected by T. E. 

Williard.) With Holcolepis. The Erythrinolepis scale figured is 7 millimeters in diameter. 

These localities are aH in the Mowry shale. 

Erythrinolepis chicoensis Cockerell, n. sp~ 

Plate XXXVI, figures 1, 2. 

Very similar to E. mowriensis but nearly circular, a little broader than long, not subtriangular. The type is 11 millimeters in diameter; 

another is 10 millimeters. This is a larger 

species than E. 1nowriensis. 
SOME AMERICAN CRETACEOUS FISH SCALES. 183 

U. S. G. S. locality 7030. Cretaceous, Chico 

group, south side of Ortigalito Creek, Cal., in 

Moreno form.ation. (Collected by Robert Anderson.) For additional particulars see description of Pomolobus chicoensis (p. 180). 

Family CTENOTHRISSIDAE. 

The remarkable genus Otenothrissa, from the 

those of the living berycoid Plectromus lugubris 

(Gilbert), from Bering Sea, but the latter lack 

the strong concentric lines on the exposed portion. The large lateral line canal or ridge is 

. also suggestive of the berycoids. 

Order INIOMI. 

c- Family ENCHODONTIDAE. 

Cretaceous of England and Syria, has the pelvic Stewart recognizes a separate family, Strafins enlarged and far forward, and the type todontidae; for Stratodus and Oimolichthys. 

species was originally described by Pictet as a 

Be1·yx. Woodward pointed out the numerous 

differences from the berycoids and placed the 

fishes in a distinct family among the Isospondyli. It must be stated, however, that the 

scales of 0. radians (Agassiz), which I am able 

to figure (Pl. XXXVII, fig. 1) through the kindness of Dr. Woodward, are extraordinnrily like 

those of the berycoid Hoplopteryx (Pl. 

L~~VII, fig. 2), though the latter have coarser 

circuli. The scales also resemble those of MyriJJnstis (I-Iolocentridae), a living berycoid. The 

lateral circuli are vertical, not transverse, as in 

the clupeoids. It seems probable, therefore, 

that Otenothrissa represents a real advance in 

the direction of the Percomorphi and should 

stand as the type of a superfamily CtenothrisGenus HALECODON Cockerell, n. gen. 

A genus of Enchodontidae related to Halec 

Agassiz is represented by the palatine and 

ectopterygoid, the suture being between the 

tenth and eleventh tooth from end in type. 

The palatine resembles that· of llalec but is 

more sl>ender, with the teeth, except the two 

apical ones, smaller. There are no long teeth 

liks those of Enchodus. The ectopterygoid, 

compared with that of Halec, is much more 

elongated basally and bears on its apical half 

a great number of s1nall teeth. The superior 

angle is above the basal end of the tooth row. 

Type H. denticulatus. 

Halecodon denticulatus Cockerell, n. sp. 

soidea, of equal rank with the Clupeoidea Plate XXXVI, figure 7. 

(Clupeoidei) and Salmonoidea (Salmonoidei) · Length of the combined bones about 54 

I examined the scales of a 1·adians (Agassiz) millimeters, the palatine slender and pointed 

and. a.· 1nicrocephala (Agassiz) in the British at end. Teeth at end of palatine about 1. 7 

Museum a number of years ago. The latter are millimeters long, sharply pointed; teeth on 

remarkable for their width and are excellently ectopterygoid about 1 millimeter long. 

figured by Woodwm·d in his work on the fishes U.S. G. S.locality 3870. Cretaceous, Aspen 

of the English chalk, Plate XVIII, figure 9. shale, near Spring Valley, Wyo., in the SW. i 

Figure 8 of the same plate, based on a scale from SW. i sec. 24, T. 15 N., R. 118 W. (Collected 

Reigate, Surrey, is e\Ticle.ntly quite distinct. It by A. R. Schultz.) With it are various scales, 

is extremely broad, with about 12 basal·radii including poorly preserved Holcolepis, probarranged fanwise, and the apical margin bears ably transversus. 

long spinelike teeth. Except for the shape, I-Ialecodon is doubtless without scales but 

this resembles the scales of the Gonorhynchi- probably with some dermal scutes. A. S. 

dae.1 It may be designated GonorhynchoJJS Woodward 2 says of Halec: "A regular squa-

(.n. gen.) woodwardi n. sp., and may be sepa- mation of very sn1all scales, the exposed area 

rated f•·om the gonorhynchid Oharitosomus by of each quadrangular in shape; no enlarged 

the shape of the scales·. The latter genus, with scutes." In a later work, however, 3 he states· 

elongate scales, is known from the Cretaceous that no traces of scales have been observed in 

of Westphalia and S~ia~ · AuloleJJis Aga~si~, ·the species described, but enlarged dermal 

the other genus ascribed to the Ctenothr1ss1- scutes· occur on the tail. All reference to 

dae, h~s totally di~erent cycloid scales. It scales is omitted from the generic diagnosis, 

occurs m the Tt.uon1an of Sussex, Kent, and and thus Flalec iri this respect agrees with the 

Surrey. The scales resemble in a general way -------'------'-·----------

' Catalogue of fossil fishes in the British l\~useum, pt. 4, p. 212, 1901. 

1 Comoare Am. Mus. Nat. Hist. Dull., v.ol. 3, pl. 4, fig. 4, 1890. s The fossil fishes of the English chalk, p. 55, 1902. 
184 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

other Enchodontidae. No doubt llalecodon 

has similar features. 

Genus CIMOLICHTHYS Leidy. 

The American forms from the Niobrara of 

Kansas, described under five names by Cope, 

are now considered to represent a single 

species, 0. nepaholica (Cope). A. specimen 

(Colorado Univ. Mus. 5388) collected by Prof. 

Mead in the Benton (Cretaceous) west of 

Laramie, Wyo., represents the top of the .head 

and agrees excellently with this genus. The 

skull was a trifle smaller and somewhat narrower than that of 0. lewesiensis Leidy, and 

also narrower than the A:inerican 0. nepaholica. 

No doubt a distinct species is indicated, but 

more material is desirable. It is not certain 

that Stratodus can be distinguished from 

Oimolichthys by the parts here preserved. 

Genus ENCHODUS Agassiz. 

Enchodus sp. 

Plate XXXVI, figure 9. 

The operculum of a species of Enchodus was 

discovered in the Colorado shale of the Milk 

River coal field, Mont. U. S. G. S. locality 

6187, in sec. 3, T. 29 N., R. 19 E., in black shale 

south of Miller's No.1 ranch. (Collected by L. 

J. Pepperberg.) Numerous species are known 

from the Niobrara of Kansas. 

Family TOMOGNATHIDAE. 

The only known representative of the Tomognathidae, Tomognathus mordax Dixon, is 

founded on fragments from the chalk of Kent, 

Sussex, anQ Surrey. It is· said to suggest 

affinity with the deep-sea Stomiatidae. No 

scales are mentioned in the description, and 

there presumably were none, as in the living 

forms supposed to be related. 

Family MYCTOPHIDAE. 

The family Myctophidae has been made a 

depositary for miscellaneous more or less obscure genera. Ichthyotringa Cope, from the 

Niobrara of South Dakota, has been referred 

to Rhinellus Agassiz, a genus of the Westphalian and Syrian Cretaceous. Hay considers 

the genus to belong to the Dercetidae (Heteromi), but it has been regarded as the type of a 

distinct family, Rhinellidae, though Dr. D. S. 

Jordan (in letter) doubts the validity of this 

course. Four species of Sardinius or Leptosomus, small fishes with (at least in two of them) 

cycloid scales, are described from the N~o brara 

of South Dakota. I can add nothing to Hay's 

account. Osmeroides illustrans (Woodward), 

described under Sardinioides, from the chalk 

of Kent, shows affinity with the Aulopidae. 

Family NOTACANTHIDAE. 

Pronotacanthus Woodward is from the Cretaceous of Mount Lebanon, Syria. No scales 

can be distinguished. The modern representatives of the family are described as having 

very small cycloid scales. 

Order APODES. 

Family ANGUILLAVIDAE. 

Anguillavus Hay, from the Cretaceous of 

Mount Lebanon, retains the pelvic fins. The 

scales are said to be rudimentary or absent. 

Family URENCHELYIDAE. 

Urenchelys Woodward, from the Cretaceous 

of Mount Lebanon, differs from Tertiary and 

living eels by having a distinct caudal fin. 

The scales are described as ''rudimentary." 

A species provisionally referred· to the same 

genus occurs in the· Turonian of Sussex and 

Kent. 

Family ENCHELIIDAE. 

Enchelion Hay, from Mount Lebanon, has 

no scales. 

Order HETEROMI. 

Family HALOSAURIDAE. 

Genus ECHIDNOCEPHALUS Von der Marek. 

Echidnocephalus? americanus Cockerell, n. sp. 

Plate XXXVI, figure 10. 

Scale subquadrate, longer than broad, 3 

millimeters wide; nucleus subapical; apical 

margin not ctenoid but ragged and free from 

circuli (exactly as in living Halosaurus); circuli 

very distinct, the lateral ones parallel with 

margin; nine basal radii, very distinct, arranged 

fanwise; lower margin deeply crenate. 

U. S. G. S. locality 5138. Brackish-water 

beds of Mesaverde formation, about 26 miles 

northeast of Rock Springs, Wyo., in sec. 15,. 

T. 21 N., R. 103 W. (Collected by V. H. 

Barnett.) The character of the fish suggests 

marine conditions. The scale agrees excel-· 

lently with the modern Halosauridae, such us 

Halosaurus and Aldrovandia, differing only in 

'• 
SOME AMERICAN CRETACEOUS FISH SCALES. 185 

the 1nore ordinary rounded nuclear area, which 

is elongated in the li,-ring fishes. 

Echiclnocephalus, from the Upper Cretaceous 

of Westphalia, is said to be essentially identical 

witl~ Halosaurus, so I refer the scale provisionally to that genus. 

Echidnocephnlus? pacificus Cockerell, n. sp. 

Plate XXXVI, figure 11. 

Scale 6 millimeters wide, cycloid, subquadrate, rounded apically; sides rather convex; 

laterobasal corners very obtuse, not salient; 

nucleus just below the apex; six basal radii, 

rather widely spaced, arranged fan wise; basal 

n1m·gin shallowly crenate. This is more like 

Ilalosaurus, whereas E. ? american us is like 

Aulrovandia, the very apical· nucleus and absence of deep basal crenation being Ilalosaurus 

characters. 

The extre1nely apical nucleus also occurs in 

Bathysaurus agassizi, which, however, has subcircular scales without a trace of radii. 

U.S. G. S. locality 7027. Cretaceous, Chico 

group, foothills between Little Panoche and 

Ortigalito creeks, Cal., in first canyon south of 

Laguna Seca Creek, in limy layer between lower 

gray sandstone and fossiliferous grit bed in 

upper part of Moreno formation. (Collected 

by Robert J\nderson.) 

Family DERCETIDAE. 

A. S. Woodward says of the Dercetidae: 

"Ordinary scales small or wanting, but two or 

n1ore continuous paired series of enlarged 

scutes along flanks; no median dorsal or ventral 

scutes.'' The scales are n1ore or less triangular, the outline resembling that of shark teeth 

(Isurus). The type of Dercetis is D. scutalus 

Agassiz, from the Cretaceous of Westphalia. 

According to Woodward these fishes are apparently allied to the I-InJosauridae and Notacanthidue. If so, they should be placed in the order 

1-Ieteromi. Leptotrachelus longipinnis Cope, 

referred to the Dercetidae, occurs in the Niobrara of South Dakota. Triaenaspis virgulatus 

Cope, also from the Niobrara of South Dakota, 

is referred by Woodward to Leptotrachelus, but 

I-Iay states that the genus Triaenaspis is valid. 

Leptotrachelus alSo occurs in the Upper Cretaceous of England, Westphalia, and Syria. 

Boulenger refers the Dercetidae to the Heteromi. 

Order HAPLOMI. 

Family CROSSOGNATHIDAE. 

Orossognathus Pictet, fron1 the N eocomian of 

Switzerland and Hanover, is said to have the 

scales large, very deeply overlapping, smooth, 

and not serrated or crenulated on posterior 

margin; a simple tube pierces the lateral line 

scales. Syllaemus Cope was formerly referred 

to this family, but Woodw:ard now considers it 

a primitive clupeoid. It has not the transverse circuli of the scales of Clupeidae. 

Apsopelix and Pelecorapis of Cope have been 

listed under Crossognathidae; Hay placed the 

first doubtfully in Albulidae, the second in 

Mugillidae. 

Apsopelix sauriformis Cope came fron1 Bunker I-Iill station on the Union Pacific Railroad 

of Kansas. Mr. T. W. Stanton teUs me that 

this is certainly in the Benton. Cope says that 

the scales are ''large and cycloid. They do not 

present a trace of radii but are. marked with 

fine and close concentric grooves [circuli]; these 

assume a vertical direction on the exposed surface, and are there more irregular, the more marginal ones terminating above and below. But 

few · (i. e., the central) grooves are truly 

circular.'' 

Order SYNENTOGNATHI. 

Family HEMmAMPHIDAE. 

Genus HEMILAMPRONITES Steinla. 

The generic name Hemilampronites was published by Geinitz from Steinla's manuscript for 

certain scales found in the Turonian of Saxony. 

The species was called H. steinlai Geinitz. As 

a' matter of fact the scales agree well enough 

with Hyporhamphus and would be referred to 

that genus without question were they not 

from the Cretaceous. 

Hemilarnpronites hesperius Cockerell, n. sp. 

Plate XXXVI, figure 13. 

Scale 12 millimeters in diameter, broader 

than long, cycloid, without radii (Hyporhamphus has a few); circuli of apical field extremely fine and regular, extending across 

scale; the other circuli much coarser and 

widely spaced at sides, where they pass transversely and more or less obliquely (especially 

above) to the margin, the upper nearly at right 

angles with the fine circuli of the apical field. 
186 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1918. 

Differs from II. steinlai by the absence· of basal 

radii and the oblique upper lateral circuli. 

U.S. G. S.locality9190. Cretaceous, Fox Hills 

sandstone, Greeley quadrangle, Colo., in second 

large ravine 2! miles south of Milliken and 

half a mile west of railroad track near Wildcat Mound, in, sec. 23, T. 4 N., R. 67 W. (Collected by T. E. Williard.) 

A related fish (Ilemiramphus edwardsi Bassani) has been found in the upper Eocene· near 

Verona. Regan suggests that Oobitopsisfrom the 

lower Oligocene of France, referred by Woodward to the Ammodytidae, may belong to the 

same group as the fishes now discussed, in the 

immediate vicinity of Ohriodorus, if indeed distinct from that genus. No scales were found 

on the fossil Oobitopsis. Ammodytid scales 1 ar·e 

very unlike those of the Hemiran1phidae. 

Order PERCOMORPHI. 

Suborder BERYCOIDEI. 

Family PLATYCORMIDAE Jordan (in letter). 

Platycormus Von der Marek, from the Cretaceous of Westphalia, is described by Woodward as having the scales ctenoid, of moderate 

size, more or less orm~mented with granulations, and extending over the opercular apparatus, head, and base of median fins. There are 

no enlarged or thickened scales. This genus, 

along with Omosoma Costa, from Mount Lebanon, and Berycopsis Dixon, has been provisionally regarded as belonging to the Stromateidae. It is also to be noted that the Creta-

~eous scales figured by Geinitz in the. work 

already cited (especially his fig. 3; fig. 4 may 

be latinucleate) as Aspidolepis steinlai agre,e 

with those of the Stromateidae (Poronotus). 

Family BERYCOPSIDAE Jordan (in letter). 

Berycopsis Dixon is represented by three 

species in the English chalk. At the British 

Museum I examined the large broad scales of 

B. major Woodward, froni the Middle Chalk of 

Cuxton, Kent. They are about 25 millimeters 

broad, with fine grooving toward the apex; 

they are not strictly ctenoid. These scales are 

extremely like those of Hoplopteryx lewesiensis. Berycopsis elegans Dixon, the type of 

the genus, has much smaller scales, and it 

seemed to me hardly possible that it could be 

congeneric with B. mqjor. Woodward states, 

1 See Gill, Theodore, U.S. Nat. Mus. Proc., vol. 28, p. 162, 1904. 

however, that the structural characters of the 

two are about the same. B. pulchellus (Dixon) 

is allied to B. major. 

Family HOPLOPTERYGIDAE Cockerell, n. fam. 

Based on HoplojJteryx Agassiz. Resembling 

the Trachichthyidae, but anal spines four, as in 

Berycidae; scales as in Holocentridae. Dorsal 

fin without the notch or division of the 

Holocentridae, and its spines much fewer (six). 

Anal fin very much shorter than in Beryx, but. 

dorsal longer. Although the scales of Hoplopteryx resemble those of B erycopsis, the fish 

is very different in a number of characters and 

can not be very closely related. Both anal and 

dorsal fins of Berycopsis are extremely long. 

Beryx insculptus Cope, from. the Cretaceous of · 

New Jersey, is very imperfectly known, but 

the scales agree with Hoplopteryx and not with 

Beryx. It may be· provisionally called Flop-· 

lopteryx? insculptus. 

The berycoid fishes were certainly well 

developed in Cretaceous time, and to-day we 

seem to have only remnants of a once more 

numerous group. The modern families, for· 

scales of which I am indebted to Dr. D. S. 

Jordan, the United States National Museum, 

the United States Bureau of Fisheries, and the, 

Museum of Comparative Zoology, ~}ave the 

following scale characters: 

. Polymixiidae: Polymixia japonica Stein-· 

dachner has very broad scales, with strongly 

crenulated lower margin, and the apical margin 

strongly, irregularly dentate. It differs from 

the Holocentridae at once in the broad fanlike 

basal undulations rather than distinct radii, 

though it is approached in this by Ostichthys. 

It differs from Ostichthys by the much smaller, 

irregular teeth, and radically in the widely· . 

spaced circuli, the lateral ones oblique and. 

entering the margin. In. Ostichthys the circuli 

are excessively fine (though the scale is much. 

larger), and the lateral ones are vertical. I 

know of no Cretaceous scale like that of Poly-· 

m~x~a. 

Holocentridae: The holocentrid scale seems. 

to· be the ancient one of the group, to judge, 

from the fossils, though the fins of the modern. 

family are much modified. The very strong, 

widely spaced apical keels terminating in. 

teeth, so well shown in the scale figured by· 

Geinitz and quite wrongly atrtibuted to Mac-· 

ropoma ma;ntelli, appear (even more widely 
SOME AMERICAN CRETACEOUS FISH SCALES. 187 

spaced) in the living Ostichthys pillwaxi, from 

the I-Iawaiian Islands (Pl. L~XVI, fig. 8). 

Jlfy1-ipristis scales differ from those of Ostichthys by the much closer teeth, about three to 

one. Flammeo scales are not nearly as broad 

as those of the genera just mentioned, and the 

basnJ n1argin has a distinct median prominence, sometin1es broken up i'nto several little 

ones in F. scythrops. Holocentrus scales are 

broad, usually with several radii close together in the middle of the base. 1 The apical 

teeth are like those of a coarse comb, not 

keeled as in Ostichthys and the Geinitz scale. · 

Berycidae: Scales of Beryx splendens Lowe 

are cycloid, with the broad hyaline marginal 

area beset with small tubercles or spines. In 

other species, as B. lineatus, the n1arginal area 

is beset with long spines, the n1ost apical projecting beyond the margin. Basal radii are 

feeble or absent.. The structure of the apical 

field is thus different in the Berycidae from 

that of the I-Iolocentridae. Jn the former 

there are spines scattered over a surface, in the 

latter strong ridges or apical teeth. The true 

berycid type apparently does not appear 

an1ong the Cretaceous fossils. 

Tracbichthyidae: Trachichthys australis has 

the broad and very dense scales constructed 

after the type of the Berycidae, the apical 

field being densely spinose. Dr. Jordan kindly 

sends me scales of two other genera, which he 

for1nerly placed with, the Berycidae but has 

n1ore recently referred to the Trachichthyidae. 

They are utterly diverse fron1 each other and 

frmn the other berycoids here discussed. 

Plect?'omus lu.gubris (Gilbert), from the vicinity 

of Bogoslof Island, Bering Sea, has subquadrate cycloid scales, with widely spaced circuli, 

and three or four basal radii arranged fanwise. Oaulolepis longidens, fron1 deep water 

off I-Iawaii, has very small roundish scales, with 

four or :five very widely spaced spinelike marginal projections. 

Monocen tridae: M onocent1-is japonicus has 

the scn.les with a high central keel or crest, but 

otherwise it is of the Trachichthys type, with 

spinose apical field. 

We n1ust evidently consider that the modern 

berycoids are vn,riously specialized descendants 

of the Cretaceous forms, none of them retaining the sarne con1binations of characters. The 

I Sco U.S. Dur. l<~isheries Dull. for 1912, pl. 36, fig. 26. 

precise arrangement of the Cretaceous genera 

for the present remains uncertain. Woodward 

figures the scales of the English Cretaceous 

llomonotus Dixon and Trachichthyoi(les Woodward. Both have scales of the holocentrid 

type, not of the berycid-trachichthyid type. 

The opercular apparatus of Trachichthyoides 

readily separates it from lloplopteryx. Some 

of the genera, as Dinopteryx Woodward, from 

Mount Lebanon, have cycloid scales. 

The total. absence of berycoids from the interior region of the United States has seemed. 

ren1arkable. The Cretaceous scales from the 

Rocky Mountain region that I have examined 

do not include any undoubted berycoids, 

though. a few poorly preserved specimens, 

which I have not ventured to describe, might 

conceivably be aberrant berycoids. Cope's 

genus Pelecorapis is of uncertain affinities. 

The scales of P. berycinus Cope, as figured by 

him, closely resemble those of Hoplopteryx? insculptus (Cope). The type of the genus is, 

however, P. varius Cope, found in Kansas, 

almost certainly in the Benton. It is said to 

have abdominal ventral fins, and to be related 

in a general way to the Scombresocidae, Atherinidae, etc. It can not well belong to the 

berycoids, nor does Cope's account of the 

scales suggest such a reference. The second 

species, P. berycinus, is of very doubtful 

generic position. It is equally uncertain as to 

locality and age, and may very well not be 

from Mon~anr~, as Mr. Stanton informs me. 

We are thus still left without berycoids in the 

Cretaceous mediterranean sea of America. 

Order ACANTHOPTERI. 

It is possible that the Stromateidae existed in 

Cretaceous time. The scale of Aspidolepis 

steinlai Geinitz, from the· Turonian of Saxony, 

certainly resembles that of the living Poronotus. 

It is cycloid, with the lateral circuli more or 

less angled. Omosoma Costa, from Mount 

Lebanon, has been provisionally referred here. 

Woodward describes the scales as small; 

smooth, and cycloid, apparently longer than 

deep, extending over the opercular apparatus, 

head, and base of anal and dorsal fins. Woodward 2 remarks that the Cretaceous fishes 

which he provisionally assigned to the Stromateidae are primitive scombroids of uncertain 

s The fossil fishes of the English chalk, p. 5, 1902. 
188 SHORTER CONTRIBUTIONS TO "GENERAL GEOLOGY, 1918. 

affinities. It must be said that the stromateid nitely assignable to a known genus. Type 

scale of to-day is very similar to that of. the 0. coloradensis. 

scombroids, and it is thus easy to ·suppose that 

the Cretaceous :fishes were rather of the latter 

than the former group. 

Centrarchites coloradensis Cockerell, n. sp. 

Carangidae are recorded from the Cretaceous Plate XXXVI, figure 12. 

of Europe and Syria., the principal genus being Scale subquadrate, transverse diameter 9 

Aipichthys Steindachner, with small, thin, ~illimeters; apical margin not distinctly dencyt•loid scales and a series of ventral ridge tate, but apical field with a broadly triangular 

scales on the short abdominal region before ctenoid patch, as in the young of Ambloplites; 

the dorsal :fin. Bathysoma lutlteni J!avis, from nucleus far apical of middle, just below lower 

the Danian of Scandinavia, said by Wood- ·end of ctenoid patch, the surrounding circuli 

ward 1 to be "very curiously specialized." transversely oval (more so than in modern 

Prolates Priem, with "scales small and very genus); basal radii occupying about middle 

:finely serrated," is from the Upper Cretaceous third (transversely) of scale, about ni:rie, close 

of France and has been referred to the Perci- together, with very :fine transverse circuli bedae. So far as I know, the typical percoid tween; lateral circuli parallel with margin. 

scale does not appear in the Cretaceous, but u. s. G. S. locality 7087. Eocene, Coalis :first found near the base of the Tertiary, in mont formation about 1 mile southwest of 

a fresh-wat~r deposit, as described below. . Walden, Colo. 1

(Collected by A. L. Beekly.) 

Family CENTRARCHIDAE. 

Genus CENTRARCHITES Cockerell, n. gen. 

This is Beekly's locality 1.2 With it is a fragment of a Viviparus and a fragment of a Laurus-like leaf. There is also another species of 

Fresh-water :fishes with scales agreeing with :fish scale, nearly· circular, with very fine cirCentrarchidae or Micropteridae but not de:fi- culi, possibly salmonoid. 

1 The fossil fishes of the English chalk, p. 253, 1912. s u.S. Geol. Survey Bull. 596, p. 63, 1915. 
• 

PLATE XXXI. 

189 
• 

• 

· PLATE··XXXI. 

FIGURE 1. Petalolepis? fibrillatus Cockerell (p.172). Type, X 6. U. S. G. S. locality 5094. U. S. N. M. catalogue 

No. 8662. 

2. Cycloides? incertus Cockerell (p.l73). Type, X 3. U. ~G. S.locality 5177. U.S. N .M. catalogue No. 8663. 

3, 4. Holcolepis pulchellus Cockerell (p. 174): 

3. Type, X 8. U. S. G. S. locality 7110. U.S.N. M. catalogue No. 8664. 

4. Another specimen, X 6. U. S. G,. S. locality 7108 ... U.. S. N. M. catalogue No. 8665. 

5. Holcolepis delicatus Cockerell (p.175}: .. 'J_'y_pe, X "4. u.·~. G. S.locality 8916. U.S.N. M. catalogue No. 

8666. 

6-13. Holcolepis transversus Cockerell (p. 175): 

6. Type, X 4. U. S. G. S. locality 6682. U.S.N. M. catalogue No. 8667. 

7. X 3. U.S. G. S. locality 6681. U.S.N. M. catalogue No. 8668. 

8. X 3. U.S. G. S. locality 6713. U.S.N. M. catalogue No. 8669. 

9. X 4. U. S. G. S. locality 6682. U. S. N. M. catalogue No. 8670. 

10. X 4. U. S. G. S. locality 6713. U. S. N. M. catalogue No. 8671. 

11. X 4. U. s·. ·a: S. locality 3417. ·· U. S; N. M. catalogue No·: 8672. 

12. X 4. U.S. G. S. locality 6682. U.S.~· M. catalogue No. 8673. 

13. X 3. U.S. G. S. locality 4421. U.S.N. M. catalogue No. 8674. 

190 

• 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 120 PLATE XXXI 

2 

5 

3 

6 7 

10 

8 

11 12 13 

CRETACEOUS FISH SCALES 
0 

'• 

! 

PLATE XXXII. 

191 

/ 

• 
PLATE XXXII. 

F'IGURE.l. Holcolepis obliquus Cockerell (p.l75). Type, X 3. U.S. G. S.locality442l. U. S.N.M.catalogueNq. 

8675. 

2. Holcolepisf mandible, X 2 (p. 175). Carbon County, Wyo. U.S.N. M. catalogue No. 8676. 

3. Pachyrhizodus scale from Cretaceous of England. After Woodward, Geol. Assoc. Proc., vol. iO, pl. I, fig. 8, 

1888 (p. 174) .. 

4. Helmintholepis vermiculatusCockerell (p. 176). Type, X 3. U.S. G. S.locality 9184. U.S.N. M. catalogue 

No. 8677. · 

5. Hypsodonf granulosusCockerell (p.l78). Type, X 4. U.S. G. S.locality 4874. U.S. N .M .catalogue No. 

8678. 

, 6, 7. Hyposodonf radiatulus Cockerell (p. 178): 

6. Type, X 3. U. S. G. S. locality 5177, U.S.N. M. catalogue No. 8679. 

7. Latinucleate scale, X 3. U.S. G. S. locality 5174. U. S. N. M. catalogue No. j680. 

8. Hypsodon audax (Leidy). Scale, X 2 (p.177). U.S. G. S.l'Jcality 8354. U.S.N. M. catalogue No. 8681. 

192 

• 

• 
U.S. GEOLOGICAL SUHVEY 

6 

7 

PROFESSIONAL PAPER 120 PLATE XXXII 

2 

8 

CRETACEOUS FISH SCALES 

3 
• 

• 

PLATE XXXIII. · 

() 

193 

·"' 
•, 

, 

• 

• • 

PLATE XXXIII. 

FIGURES 1, 2. Hypsodon audax (Leidy) (p. 177): 

1. Specimen showing several scales and parts of skeleton. University of Kansas collection. 

2. Part of same specimen, more enlarged. 

194 

• 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 120 PLATE XXXIII 

2 

CRETACEOUS FISH SCALES 
· .... , ... 

==============================================::== . ~-

PLATE 

I 

XXXIV~ •• ' 

195 

•• ; J 
0 

PLATE XXXIV. 

FIGURE 1. Chicolepis punctatus Cockerell (p. 177). Type, X 3. U.S. G. S.locality 7030. U.S.N. M. catalogue No. 

8682. 

2. Hypsodon lowii (Stewart) Cockerell (p. 178). Scale, X 2. U.S. G. S. locality 7294. U.S.N. M. catalogue 

No. 8683. 

3. Ichthyodectes sp. (p. 179). Lateral line scale, X 4. U. S. G. S. locality 2402. U. S. N. M. catalogue No. 

8684. 

4. Ichthyodectessp. (p.179). Lateral line scale, X 4. U.S. G. S.locality 7277. U.S.N. M. catalogue No. 8685. 

5. Pomolobus? chicoensis Cockerell (p.180). ·Type, X 10. U.S. G. S. locality 7030. U.S.N. M. catalogue 

No. 8686. · 

6-12. Cretaceous fish scales from Turkestan (p. 179). Copied from G. D. Romanowsky, Materialui dlya geologii 

Turkestanskago kraya, pts. 2, 3, 1884, 1890. 

6-8. Hypsodon sp. Figured as Cladocyclus st1·ehlensis Geinitz. Op. cit., pt. 3, pl. 17, figs. 6a-c. 

9. Hypsodon? sp. Figured as Osmeroides lewesiensis (variety). Idem, pt. 2, pl. 23, fig. 4a. 

10. Ichthyodectes sp. Figured as Cladocyclus strehlensis. Idem, pt. 2, pl. 23, fig. 4b. 

11. Ichthyodectes? pectinolepis. Figured as Osmeroides pectinolepis Romanowsky. Idem, pt. 3, pl. 17, 

fig. 5. 

12. Undetermined scale. Figured as Beryx sp. Idem, pt. 3, pl. 17, fig. 4. 

13. Fragment of Mowry shale, X 2, showing scales of Erythrinolepis mowriensis, Leucichthyops vagans, and 

Holcolepis transversus (pp. 182, 180, 175). U. S. G. S. locality 4896; north of Wolf Creek canyon, Big 

Horn Mountains, Wyo. U. S. N. M. catalogue No. 8687. 

196 
U. S. GEOLOGICAL SURVEY 

3 

6 

11 

12 

PROFESSIONAL PAPER 120 PLATE XXXIV 

4 

7 

13 

CRETACEOUS FISH SCALES 

2 

5 

9 
G 

PLATE XXXV. 

' . • 

197 

• 
PLATE XXXV. 

FIGURES 1-15. Leucichthyops vagans Cockerell (p. 180): 

1. Type, X 4. U.S. G. S. locality 7095. U.S.N. M. catalogue No. 8688. 

2, 3. Two scales, X 3. Carbon County, Wyo. U.S. N'. M. catalogue Nos. 8689, 8690. 

4. Scale, X 4. Black Hills, S. Dak. U.S.N. M. catalogue No. 8691. ' 

5. Scale, X 3. U.S. G. S. locality 3880. U.S.N. M. catalogue No. 8692. 

6. Scale, X 3. U.S. G. S. locality 7275. U. S. N. M. catalogue No. 8693. 

7. Narrow scale, X 3. U. S. G. S. locality 6681. U. S. N. M. catalogue No. 8694. 

8. Scale, X 4. U.S. G. S. locality 8916: U.S.N. M. catalogue No. 8695. 

9. Narrow scale, X 4. U. S. G. S .. locality 7110. U.S.N. M. catalogue No. 8696. 

10. Laterallinescale, X 4. U.S. G .. S. locality 6682. U.S.N. M. catalogue No. 8697. 

11. Lateral line scale, X 4. U.S. G. S. locality 7095. U. S. N. M. catalogue No. 8698. 

12. Laterallinescale, X 4. U.S. G. S.locality 7110. U.S.N. M. catalogue No. 8699. 

13. Laterallinescale, X 4. U.S. G. S.locality 7100. U.S.N. M. catalogue No. 8700. 

14. Laterallinescale, X 4. U.S. G. S. locality 7110. U. 0S. N. M. catalogue No. 8701. 

15. Latinucleate scale, X 4. Black Hills, S.Dak. U.S.N. M. catalogue No. 8702. 

16. Cyclolepis stenodinus Cockerell (p. 181). Type, X 4. U.S. G. S. locality 9190. U. S. N. M. catalogue No. 8703. 

198 

• 
U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 120 PLATE XXXV 

2 

, 4 

6 

8 

10 

7 

13 

14 15 16 

CRETACEOUS FISH SCALES 
,. 

PLATE XXXVI. 

199 

• 
PLATE XXXVI. 

Ti'IGURES 1, 2. Erythrinolepis chicoensis Cockerell (p. 182): 

1. Type, X 4. U.S. G. S.locality 7030. U. S. N. M. catalogue No. 8704. 

2. Smaller scale, X 4. U. S. G. S. locality 7030. U. S. N. M. catalogue No. 8705. 

3-6. Erythrinolepis mowriensis Cockerell (p. 182): 

3. Type, X 4. U. S. G. S. locality 6713. 

4. Scale, X 4. U .. S. G. S. locality 6713. 

5. Scale, X 4. U. S. G. S. locality 6713. 3-5, U. S. N. M. catalogue No. 8706. 

6. Scale, X 4. U. S. G. S. locality 4941. U. S. N. M. catalogue No. 8707. 

7. Halecodon denticulatus Cockerell (p. 183). Type. Palatine and ectopterygoid, X 1.5. U.S. G. S.loca.lity 

3870. U.S.N. M. catalogue No. 8708. 

8. Ostichthys pillwaxi (p. 187). Apical region of scale, X 1.85. Honolulu market. 

9. Enchodus sp. (p. 184). Operculum, X 2. U. S. G. S. locality 6187. U.S. N. M. catalogue No. 8709. 

10. Echidnocephalus? americanus Cockerell (p. 184). Type, X 8. U. S. G. S. locality 5138. U.S.N. M. 

catalogue No. 8710. 

·n. Echidnocephalus? pacificus Cockerell (p. 185). Type, X 4. U.S: G. S. locality 7027. U.S.N. M. catalogue No. 8711. · · 

12. Centrarchites coloradensis Cockerell (p. 188). Typ,e, X· { Eocene. U. S. G. S. locality 7087. 

U.S.N. M. catalogue No. 8712. 

13. Hemilampronites hesperius Cockerell (p. 185). Type, X 6. U. S. G. S. locality 9190. U. S. N. M. 

catalogue No. 8713. 

14. Latinucleate (regenerated) scale of undescribed species, with marginal teeth resembling· those of the 

berycoids, X 3. U. S. G. S. locality 4867. Cretaceous, Mowry shale, sec. 1, T. 26 N., R. 88 W., 

near North Rawlins, Wyo. U. S. N. M. catalogue No. 8714. 

15. Scale of undescribed species with marginal teeth suggesting the berycoids, X 10. U. S. G. S. locality 

4426. Cretaceous, Mowry shale, SE. i sec. 27, T. 33 N., R. 74 W., about 5 miles southwest of Careyhurst, Wyo. U. S. N. M. catalogue No. 8715. 

16. Scale of undescribed species, X 10. U. S. G. S. locality 6603, SE. i sec. 18, T. 1 S., R. 10 W., Uinta 

special base line, Utah. Said to be Mowry shale. The collection contains plant remains and may 

be from a fresh-water deposit. U. S. N. M. catalogue No. 8716. • 

17. Scale of undescribed species, perhaps clupeid, with fine transverse circuli, X 4. Transverse diameter 

12.5 millimeters. From the same station as figure 16. Presumably fresh water. U. S. N. M. catalogue No. 8717. . 0 

200 
U.S. GEOLOGICAL SURV J.;Y 

7 

t 

14 

15 

PROFESSIONAL PAPER 120 PLATE XXXVl 

10 11 

16 

CRETACEOUS FISH SCALES 

6 

rrtt1'Mt11111 rtr _1! ,\1\rll! . . J~ r . 8 

12 

17 
PLATE XXXV.II. 

201 
• 

PLATE XXXVII. 

FIGURE 1. Ctenothrissa radians (Agassiz) (p. 183). Cretaceous of England. From a specimen in the British Museum. 

2. Hoplopteryx lewesiensis (Mantell) (p.' 183). . Cretaceous of England. From a specimen in the British 

Museum. · 

202 

'\ 
.., -- ... ~ 

U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 120 PLATE XXXVII 

2 

CRETACEOUS FISH SCALES 
\ 

\ 

INDEX. 

A. I rage. 

Ac~nthoptcrl .......... ; ............... , ....................... 187-188 

Acipcnseri<lao, possible occurrence of..· ...................... ·.--. 171-17 

Acknowledgments for aid .. : ........................... 1,17, C, 130,169 

AJnslio, Ga., section cast or....................................... 75. 

Albany, Ga., section north of.................................... 79 

Albulldae, existence of, in Cretaceous time....................... 112 

Alden, W. C., ack"llowlodgmont to ................ ,.............. 17 

Alinomont diagrams, accuracy and advantage of. .•............. 126-128 

usc of. ....................................... ; ......... , .... 123-126 

Alluvium, occurrence of, In northcostcrn Montana ............. :. 35-37 

American Museum of Natural History, acknowledgment to....... 1li9 

Amsden formation, correlation of................................ 118 

Angu1llavidao ............... ; .. :. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184 

Annona tongue of tho Austm chalk, nature !llld distribution of. 151-152 

Anticline on Gmvlna Island, Aloska, plato sho\v4lg.............. 88 

Apodcs.... .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184 

Austin chalk, Annona tongue of,.naturc and distribution of. ... 151-152 

Annona tongue of, plates showing ...................... ·"'·.... 14.C: 

clays and sands of tho age of ............................... 148-1,19 

contact of, with Eagle Ford clay, plato showing· .. :........... Wi 

distribution or ............... ; ..................... ! • • • • • • • • • • • 148 

Fntor tongue or ............................................ 149-150 

typical o.roa of •......•........ :.............................. 148 

B. 

~adltmds near Lismos, Mont., plato showing ......... ·............ 21 

Bainbridge, Ga., fossils from ................................... -- 80-81 

Baker, H.. J?., work of. ...................... : ....... ·............. . 17 

Baldwin County, Ga., exposure of tho Barnwell forn:ution in.... . 71 

Bannock Peak, Yellowstone National Park, pluto showing ....... · 118 

Barnwell formation, areal distribution of. ............ : ........... 55-56 

' exposures !llld sections of .......................... :. . . . . . . . . . 63-77 

nanling of.................................................... . 52 

nature and thickness or. .......... : ............... · ......... :. 54-55 

stratigraphic relations of .................................... : 52-54 

structure of ................................................. :· 56 

Bossler, H.. S., acknowledgment to .......... -- .. -- ......... ,..... 42 

fossils determined by ............................ : . ........ :. · 45 

Boar paw shale, badlands of, plato showing.·: .................. ::. 21 

o-ccurronco of, in northeostem Montana ................ : .... , 30 

Beaver Creek, Mont., events In history. or........................ 37 

Beu:nctt, H. R., work of. .................................. ,..... 17 

Benton slialo, Cretaceous fishes from............................. 171 

Berry, E. W., o.cknowlodgmont to............................... 42 

cited ............................................. :.......... 55 

fossils determined by........................................ 75 

Borycoidoi. .... : ::: ..... :· .. · ............ : ....................... ·136-187 

Bcrycopsidao Jordan ..................................... :....... 186 

13ibb County, Ga., exposures of tho Barnwell formation in ....... 74-75 

Bidarbom\to, calculation of..--.--.-- .............. '......... · ...... · 11-15 

use of tol'ln .................... --.-- ... __ .... :................ 3 

Big-Muddy Crook, :Mont., bench eost and west of. ......... __ .... 19 

events in tho history of. ............................... : ...... 36-37 

Big Sandy Crook, Ga., section on................................ 71 

l31aok Prairies, ~L'ox.,looation and topography or................. 131 

:inecldoy County ,\Ga., exposures of tho Barnwell formati::m in' ... 75-76 

Blossom sand,'glauconitic clay representing ............. : .... ,... 150 

natme and correlation of ................................... 152-153 

"Bonham, Tox., trnnsition.'al clays near .. : ..... .':~· ............... 150-151 

Bow'doin domo,l\tout.,structure of. .............................. 37-38 

Bmntly, J. E., fossfls colloctod by .. .' .......... · .......... · ........ ·. 66 

section meosurod by ........... ,.............................. 59 

Brooks, Alfred H., cited .......................................... 8·1,88 

Brown, 13nrnum, o.cknowbdgmont to:. :.-.... :· ... ,.:·.-.. • .. ·.; .. : .. .. ·. 17 

·Browns Mountain, Ga., sections ncar ...................... : ...... 47-49 

. Brownstown hlo.t1; Jiatute and·correlation of:.: ............ : ...... : 154 

i.L 

Page. 

Bryant, J. T., acknowledgment to................................ 130 

Bucho.D!Ill, J. Y., determinations of carbon diJ:xide in sea water 

by ........................................... : ..... 4,14-15 

Buffalo Creek, Ga., sections ~ast·or............................... GS 

B·urke County, Ga., exposures of the Barnwell fon~atiou in...... 63 

c. 

Carbon dioxide, equilibriUDl of, with the atmosphere ............ 5, G-7 

determinations of, in watet· of the Gulf of MexicJ............ 1-16 

theoretical amount of, In sea water ............... ·............ 5 

Carbonate, calculation of. ........................................ 1!-15 

use ofterm .................................................. . 

Carbonate and bicarbonate, total, in· sea water, determination of.. i-;-9 

total, in sea water, discussion of. ........... .'................. !)..11 

Cardwell, Mont., section near ....................... ~-............ 115 

Centennial Range, Mont., plate showing.......................... 117 

shaly calcareou~ beds on, plate showing .............. '\~;..... 117 

stratigraphy of.. ........................................ : .. llli-117 

Centrarchidro . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 

Centrarchites Cockerell, n. gen.................................... 188 

... coloradensis ~o!}k,erell, n. sp ................................ 1S8, 200 

C~alker, Ga., section·'south of. ....................... :............ 70 

Chapin, Theodor~, 'I;'he structure and stratigraphy of Gravina and 

Revillagigedo islands, Aloska ......... : . ............. 83-100 

Cll.Ico group, Cretaceous f1shes from............................... 171 

Chicolepis Cockerell, n. gen ..................................... 176-177 

pmwtatus Cockerell, n. sp .................................. 177,196 

chugwater formation, stratigraphy of. ............... : .......... 119-120 

Cimolichtbys Leidy ........ : ........................ :............ 184 

Claggett shale, occurrence of. ........................ : ............ 26-27 

Claiborne group, in Georgia, formations included in ............... 49-50 

stratigraphy of ............................................ 49!-51,59 

undilforentiated deposits·or................................... 51 

sections of. ............................. : ................. 61"-62 

Clay, glauconitic, occmrence of, near Bonham, Te~L ............ 150-151 

Clupeidro .............................................. ·.......... 180 

Coal, occurrence of, in northern Montana ................. · ..... 29,32, 33 

Cochran, Ga., section north of.. .................................. 75-76 

Cockerell, T. D. A., Sol¥ American Cretaceous fish scales,· with 

notes on the clossification ond distribution of Creta-

. ceo us fishes ................... : ..................... 165-202 

Collier'· J\.t;tliur J ., Geology of northeastem Montana ............ .'. 17-3:! 

Colorado group, local subdivisions of ..... : .......... :.: .. ·:· ..... 165-167 

Columbia County, Ga., exposures of the Barnwell formation in .• 64-65 

Comanche series, age and distribution of.......................... 134 

correlation table of..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134 

formations of, in northeostem Texas ...... · .................. 1.34-144 

Con!lllt, Edwin T., work of....................................... 17 

Concretions in Lance and Fort Union formations, plates showbg. 32,26 

Condit, D. Dale, Relations of late Paleozoic q.nd early 1\Iesozoic 

formations of westem Montana and adjacent parts of 

'Vyoming ...... · . .-.. · ................................ 111-:21 

Conglomerate, exposme of, on Gravina Island,_Aloska, plato sh:nv· 

ing ....•......................... :.................... 88 

Cook, R. H., acknowledgment to................................. 130 

Cooke, Charles Wythe, and Shearer, Harold Kurtz, Deposits of 

Claiborne and Jackson age in Georgia ................ 41-81 

Cottonwood Creek, M:oht.; view on, plate showing .......... '>.... 21 

Crawford County, Ga., exposmes of the Barnwell formation in.... . 77 

Cretaceous .fish scales from Tmkestan. . . . . . . . . . . . . . . . . . . . . . . • . . 179, 196 

Cretaceous fishes, evolution of.·· ....... , ............. : . .... : ...... : 170 

Cretaceous inl!llld sea, evolution uf fishes favored by ... ,.......... 170 

Cross-bedding, eolian, in sandstone, plate showin:5................ 32 

Grossognathidae ...................................... :, . . . . . . . . . . 185 

Ctenothrissa radians (Agossiz)~ .•. : ........... · ................... 183,202 

Ctenothrissidae .....•............................. .'.... .. . . . . . . . . . . 183 

''203 
204 JiNDEX. 

Page. 

Cushman, Joseph A., acknowledgment tq.. ...... .... .... ... . .... 42 

Cuthbert, Ga., sections west of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6:! 

Cycloides? incertus Cockerell, n. sp ............................ 173,190 

Cyclolepis Geinitz................................................ 131 

stenodinus Cockerell, n. sp ................................. 181,198 

D. . Dall, W. H., fossils determined by............................... 99 

Daly, R. A., analyse's by......................................... 105 

Danville, Ga., exposure of the Barnwell formation northwest of.. U 

Denison, Tex., section north of................................... 139 

section south of ........................................... : 142-143 

section west of ............................................... · 143 

Denison formation, members of, descriptions of ................. 140-144 

Pawpaw member of, plate showing........................... 143 

Denton clay member, nature and exposures of.. ............... 140-141 

Depth, alinement diagram for computing........................ 124 

Dercetidae. ... . . . . . . . . . . . . . . . .. . ... . . . . .. . . .. . . . . . . . . . . . . . . . . . . . . 185 

Dinwoody Canyon, Wyo., section in............................. 119 

Dinwoody formation, section of.................................. 119 

Dip, projected, alinement diagram for computing................. 128 

Dittmar, W., analyses by. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

determinations of carbonat& in surface sea waters by.......... 10 

Dole, R. B., determinations of carbon dioxide in sea water by .. 2,4-5 

Dooly County, G~~· exposures of the Ocala limestone b .......... 77-78 

Dry Branch, Ga., section near .......... :......................... 43 

Duck Creek, Tex., section on..................................... 139 

Duck Creek formation, limestone member of, plate sh:J\ving .. .. .. 133 

nature and exposures of.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 

:c. 

Eagle Ford clay, contact of, with Austin chalk, plate sh:>wing.... 145 

nature and exposures of............ .. .. .. .. . .. . . . .. .. .. . .. . 146-148 

Eagle sandstone, occurrence of, in northeastern Montana......... 26 

Eastern Cross Timbers, Tex., location and topography of.. ..... 131-132 

Echidnocephalus Von der Marek ............................... 184-185 

Echidnocephalus? americanus Cockerell, n. sp ............. 184-185,200 

pacificus Cockerell, n. sp ................................... 185,200 

Ector tongue of the Austin chalk, nature and exposures of.. .... 149-150 

Ellis formation, age and stratigraphy of .... · . .'.................... 114 

contacts of. . .. . . . . . .. . . . . . . . .. . . . . . .. .. . . . . . . . . . . . . . . . . . . . . . . 120 

exposures of .................................. .' ............. 115,116 

occurrence of ............................... : ................. 24-25 

Elopidae ........•..................................... :. . . . . . . . 173-176 

Encheliidae ................................ :. . . . . . . . . . . . . . . . . . . . . 184 

Enchodontidae ................................................. 183-184 

Enchodus Agassiz ................ : . .' .......... '................. 184 

sp .....•................................................... 184,200 

Eocene formations in Georgia, section o·r. . . . . . . . . . . . . . . . . . . . . . . . . 43 

in northeastern Texas, evidence of .. · .... ~.. . . . . . . . . . . . . . . . . . 158 

Erythrinolepidae Cockerell, 11. fam .. · ........................... 182-183 

ErythrinolelJiS Cockerell, n. gen ... : ............................ 182-183 

chicoensis Cockerell, n. sp .............................. 182-183,200 

mowriens1s Cockerell, n. sp. ~ ................ · .............. 182,200 

F. 

Farmersville, Tex., structure section from a point near, to Ladonia, Tex., plate showing.............................. 155 

"Fish-bed conglomerate," exposures of.......................... 147 

nature of. .................................................. 148-149 

plate showing ......... ·....................................... 145 

Fish scales, Cretaceous, formations yielding .................... 165-167 

Cretaceous, stratigraphic distribution of. ................... 169-171 

recent, preparation of........................................ 169 

terms used in describing ................................... 168-169. 

value of, it?- determining species.............................. 168 

Fishes, Cretaceous, of Europe and America, differences between.. 170 

Flaxville gravel, occurrence of, in northeastern ~ontana.... .. .. . 35 

Flint River, Ga., sections on .... · ..................... · ............ 78-79' 

Fort Gaines, Ga.,sectionsat .•........•....•.. , ................... 61,62 

Fort Union formation, concretion in, plate showing.............. 36. 

occurrence of. ..................................... , . . . . . . . . . 32-3.'i. 

Fort Worth limestone,.nature and·exposurcs of., .............. 139-140. 

plates showing .... :.·.·.~-.... · •......•.................. ·......... 139 

Fredericksburg group, nature and distribution o~, in northeastern 

Texas ......................... · ..... ,, ................... 13.3--137 

Fucoids(?) in Fort Worth limestQne, plate showing.............. 139 

G. Pa~. 

Gallemore, Ga., section east of. . . . • . .. . . .. . .. . . .. . . .. . . . . . . . . . . . . 74 

Georgia, geologic map of part of. . . .. . • . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 

Gibson, Ga., sections near ..................................... 46-47,67 

Gilmore, C. W., fossils determined by......................... 30, 31, 32 

Girty, G. H., fossils determined by. . . . . . . . . . . . . . . . . . . . . . 23-24, 116, 120 

G lasoock County, Ga., exposures of the Barnwell formation in. . . . 67 

Goodland limestone, nature and distribution of, in northeastern 

Texas .............................................. 135-137 

plate shoWing. . . . . . .. . . . . . .. . . .. . .. . . .. . .. . . . . . . . . . . . . . . . . . . . 136 

Gordon, Ga., section south of. .................................. , 71 

Grain field near Scobey, Mont., plate showinrr.................... 20 

Grand Prairies, Tex.-Okla., location and topography of. . . . . . . . . ,132 

·Gravel pit at Wolf Point, Mont., plate showing.................. 36 

Gravina Island, Alaska, Cretaceous rocks on ..................... 97-98 

Devonian rocks on ........................................... 87-88 

geography of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83-85 

geology of •.................................................. 85-100 

intrusive rocks on ........................................... 99-100 

Jurassic rocks on.. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95-98 

Quaternary deposits on. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 

slate on, plate showing....................................... 88 

Tertiary rocks on ........................................... : 99 

Triassic rocks on ............................................. 89-9i 

Grayson marl member, nature and exposures of.................. 144 

Graywacke, exposure of, on Gravina Island, Alaska, plato showing ...... ·............................................. 88 

Great Plains, development of.................................... 18 

Grovetown, Ga., sections and exposures neat ..................... 64-65 

Gryphaea"bcaring limestone, nature and exposures of. .......... 138-139 

Gulf series, age and dist!'ibution of. ............................ 144-145 

formations of, in nvrtheastern Texas ....................... 145-158 

generalized section of, plate showing......................... 155 

H. 

Halecodon Cockerell, n. gen .................................... 183-184 

denticulatus Cockerell, n. sp. . . . . . . . . . . . . . . . . . . . . . . . . . . 183-184, 200 

Halosauridre .... · ............................................... 184-185 

Haplomi...... .. . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185 

Hazard, W. 0., acknowledgment to.............................. 169 

Helmintholepis Cockerell, n. gen.................................. 176 

vermiculatus Cockerell, n. sp ............................... 176,192 

Hen;tilamlJronitcs Stcinla ....................................... 185-186 

hcsperius Cockerell, n. sp ............................... 185,186,200 

Hemiramphidre ............................ :. . . . . . . . . . . . . . . . . . . . 185 

Henderson, J., acknowledgment to............................... 169 

Hetcromi. ..................................................... 184-185 

Hill, Robert T., cit:)d .......................................... 135,151 

work of, in northeastern Texas............................... 129 

Holcolepis Von dcr Marek ...................................... 173-176 

delicatus Cockerell, n. sp ................................... 175,190 

obliquus Cockerell, n. sp .................................... 175,192 

pulchellus Cockerell, n. sp .............................. 174-175,190 

transversus Cockerell, n. sp ................................. 175,190 

Holcolepis? mandible ....... : .............................. 175-176,192 

Hopkins, 0. B., acknowledgment to............................. 13J 

Roploptcrygidae Cockerell, n. fam .............................. 1SC--187 

Hoploptcryx lewcsiensis ........................................ 183, 202 

Houston County, Ga., exposures of the Barnwell formation m... 76 

Hyatts Bluff, Tex., description of................................ 146 

Hypsodon Agassiz ............................................. 177-179 

audax (Leidy) CockerelL. .......................... 177-178,192,194 

lowii (Stewart) Cockerell ................................... 178,196 

Hypsodon? granulosus Cockerell, n. sp ......................... 17~-179 

radiatulus Cockerell, n. sp .................................. 178,192 

I. 

Icthyodectes Cope .................................. ; .......... _. 179, 1Sv 

Ichthyodectidfe .......... ,.......................... ..... 177-179 

. Iddings, J. P., analyses by ........................... ·............... 105 

Indian Creek, Mont., canyon of, plate showing................... 116 

section on .................................................. 115-116 

Iniomi ........... · .............................................. 183-184 

J 

Jackson group, formations included in............................ 51 

stratigraphy of ......................... , ................ ···-- 51,59 

Jefferson County, Ga., exposures of the ~amwell formation in. ___ 65·67 

Jefferson River canyon, Mont., section in......................... 115 
.·~ 

• 

INDEX. 205. 

Page. 

Jones County, On., exposures of the Barnwell formatton in ....... 72-73 

Jordan, D. S., acknowlcdgmont to............................... 169 

Judith River formation, occurronce of ............................ 27-29 

K. 

Keys Mill, Ga., section at ....................................... ·. 63 

Klamichi clay, nature and exposures of ..................... : .. 138-139 

plates showing............................................... 138 

Kinchafoonco Crock, Ga., section on.............................. 79 

Kindle, E. :M.., fossils determined by ............................. 88, 89 

lGrk, Edwin, fossils determined by .... ,,........................ 93 

Knowlton, F. H., fossils determined by .......................... 34-35 

Kootenai formation, e:ll:posum of.................................. 115 

nature and correlation of .................... .' .............. 114-115 

occurrence of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 

L. 

LndonJn, Tox., structure section from, .to a point neat" Farmersville, To.--c., plate showing.............................. :155 

Lance formation, concretions in, plate showing.................... 32 

erosion forms of, plates showing. ... . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 

occurrence of. .............................. ~ .............. 30-32,33 . 

Page. 

Montana, southwestern, field work. in .......... :. . . . . ... . . . . . . . . . 111 

southwestern, map of, showing distribution of Phosphoria 

formation .. ..... .. .. .. . .. . .. .. . . . .. . . . .. . .. .. ... . . .. . .. .. .. . ll2 

stratigraphic features of. . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . J.l5-11& 

Montana group, Cretaceous fishes from........................... 171 

local subdivisions of. ........................................ 165-167 

'Moor, J. :Balch, acknowledgment to.............................. 130 

Moore, .H. F., aclmowledgment to.. . . . . . .. .. .. . .. . .. .. .. .. .. . .. . 1 

'1\:lossy Hill, Ga., section on ............ , .......................... 45-'46 

1\:lount En on, Ga., section on...................................... 64 

Mount Nebo, Utah. See Santaquin, Utah. 

Mowry shale, occurrence of, in.northeastcrn Montana.. . . . . . . . . . . . 25-26 

Myctophidro ........... ·........................................... 184 

N. 

·Navarro formation, nature and correlation of.. .................. 1.57-158 

Niobrara formation, Cretaceous fishes from......................... 171 

N otacanthidro...... •.•....... ... . . ... . . . . . . . . . . . ... . . . .. . . . . . . . . . . . . . . . . 184 

Notelops 'Voodward............................................. 176 

0. 

Lnrb Hills, Mont., location of.................................... 19 'Ocala'limestone, areal distribution or...:.' ............ ~.' ..... ~...... 58 

Leonard-Celeste monoclinal nose, Tex., description of.. . . . . . . . . . . 161 · exposures and sections of. .................... : ..... 75-76,77-81 

Leptolepidro.... ...... .. ..... ..... .. . . . .. .. . .. . . ... . . . ... .. .. .. .. . 173 naming of ................................. ~·······........... ·55 

Leucichthyops Cockerell, n. gen ................................ 180-181 nat\lre :md thich."lless of.. ..................................... '57-58 

vagans Cockerell, n. sp .' ............................ 180-181, 196, 198 stratigrapliic relations of.. ... .,................................. 57 

Lignite. See Coal. structure of. .. .. .. .. .. .. . .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . 58 

Little Keg Creek. Ga.,sect10non...... ... ......... ............... 48 ·oconee, Ga., section north of..................................... 68 

Little :Mineral Creek, To.x.,section on............................ 136 Oklahoma. See Texas, northeastern, and Oklahoma, southern. 

Little Rocky Mountains, Mont., camp in foothills of, plate Osmeroides .................................................... 173-174 

showing.............................................. 20 · o.~tua carinata bed, exposures of.. .............................. 140-141 

description of ............................................. 18,19-20 Owl Creek Mountains, 'Vyo., plate showing..................... 118 

Loughlin, G. F., Two lamprophyre dikes ncar Santaquin and 

Mount Nebo, Utai1 ................................. 101-109 

1\{. 

M:c:Bcan formation, distribution and structure or................. 51 

nature and relations of ....................................... 50-51 

sections of .................................................... 59-61 

Macon, Ga., sections southeast of. ............................. 47-48,74 

Mad.isonlimestone, features of.................................... 111 

occurrence of. . .. .. . .. .. .. .. .. .. . .. . . .. . . .. . . . . . . .. .. . . . . .. . . . 23-24 

Main Street limestone member, nature and exposures of ....... 143-144 

plates showing ............................................. 141, 142 

Mp.p, geologic, of northeastern Montana.. . . . . . . . . . . . . . . . . . . . . . . . . IS 

Map of northwestern Wyoml.ng, showing distribution of Em bar 

formation............................................ 112 

Map of south western Montana, showing distribution of Phosphoria 

formation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 

Map showing distributiOn of the Eocene formations of Georgia... 50 

Marl brook marl, correlation with ............................... 154-155 

"Saratoga" chalk member of. See Pecan Gap chalk member 

or the Taylor marl. 

Milk River, Mont., events in the hls~ory of ................ ·.· ..... 19,36 

Mis&ouri River valley, Mont., plate showing...................... 36 

Mollusks, Cretaceous, of the Niobrara, Pierre, and Fox Hill formations, differences between .......................... 170-171 

Montana, Jurassic erosion in .................................... 120-121 

northeastern, Cambrian formations in........................ 23 

Carboniferous formation in ............................... 23-24 

Colorado formation in ............................ ·. . . . . . . . 25-26 

Cretaceous formations in .... · ............................. 25-30 

Devonian rocks of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 

field work in............................................. 17 

geologic map of........................................... 18 

glaciation in... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 

Jurassic formation in ..................................... 24-25 

Montana formations in ................................... 26-30 

pro-Cambrian rocks in.................................... 23 

pre,•ious publieations on. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 

Quaternary deposits in ................................... 35-37 

settletnent or............................................. 20 

Silurian rocks of.......................................... 23 

stratigraphy or.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-37 

streams in, adjustment of................................ 39 , 

structure or. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37-3g 

surface features of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18-20 

Tertiary formations in .................................... 30-35 

P. 

Palmer, Harold S., New graphic method for determining tho depth 

and thielmcss of strata and the projection of dip. 123-128 

Park City formation, gcneraliz('d section of. .................... ll8-ll!J 

Pawpaw Creek, Tex., section on branch of ..................... 142-143 

Pawpaw sandy member, nature and exposures of.. ............. 142-143 

Pecan Gap, Tex., section east of.................................. lfiG 

Pecan Gap chalk member of the Taylor marl, basal beds of, plato 

sho\ving............................................. 154 

nature and exposures of. ................................... 15fr-lfi7 

Percomorphl ................................................... 186-187 

Perry, Ga., age of exposures south of. ............................ 44-46 

Petalolcpis?fLbrillatus Cockerell, n. sp ...................... 172-173,190 

Phosphate rock, orcurrencc of. ......................... 113,115,116,117 

Phosphoria formation, exposures of.. ....................... 115,116,117 

nature of.............................................. . . . . . . . 113 

Pikes Peak, Ga., section northwest of. ........................... 73-H 

Platycormidrc Jordan ........................... _.. . . . . . . . . . . . . . . . 186 

Plcthodontidrc ..................................................... li9 

Pomolobus Rafincsquc........................... ....... .. . .. .... 1~0 

Pomolobus? chlcoensis Cockerell, n. sp ......................... 180,196 

.Porphyry laccolith, occurrence of, in northeastern ~fontana....... 23 

Pottsboro, Tex., section north of................................. 136 

Powers, ~idncy, work of......................................... 130 

Preston, Tex., section south or................................... 134 

Preston anticline, Okla.-Tex., cause of........................... 160 

descriptiOn of .............................................. 159-160 

structure section across, plate showing........................ 155 

Protosphyraenidm, occurrence of................................. 172 

Pterothrissidre ................... · .............................. 176-177 

Q. 

Quadrll.Ilt Mountain, Yellowstone National Park, section on ..... 117-118 

Quadrant quart?.ite, exposures of.. ..................... 115,116,117,118 

nature and distribution of.. ................................ 111-112 

"Quarry" limestone, nature and exposures of.,................ 142 

plateshowing................................................ 141 

Queen Charlotte series, age of. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. gg 

R. 

Red River, Okla.-Tex., course and tributaries of................. 131 

section on.................................................... 138 

terraces on. .. .. .. .. .. . .. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . .. 132 

Reeside, J. B.,jr.,fossilsdctermined by .......................... 24-25 

26, 27, 28, 29,30,32, 92,93 
206 INDEX. 

Page. 

Revillagigedo Isla.nd, Alaska, Carboiliferous rocks on . . . . . . . . • . . . 88-89 

Cretaceous rocks on .......................................... 97-98 

geography of .................................................. 83-85 

geology of ................................................... 85-100 

intrusive rocks on ........................................... 99-100 

Jurassicrockson ........... : ................................. 95-98 

Triassic rocks on ............................................. 89,97 

Rhacolepis Agassiz............................................... 176 

Ricciardi, L., analysis by ............... :. . . . . . . . . . . . . . . . . . . . . . . . . 105 

Richmond County, Ga., exposure of the Barnwell formation in ... 63-64 

Roberta, Ga., sections east of..................................... 77 

Roberts, G.a., section northeast of................................ 72 

Robinson, H. M., work of........................................ 130 

Rock Bluff, Tex., section at...................................... 134 

Rock Creek, Mont., gorge of, plate showing....................... 2o 

Ross Hill, Ga., sections on ....................................... 44-45 

Ruppin, E., determinations by, of C03 and HC03 in the North 

Sea.................................................. 10 

s. 

Salmonidae. • • . • .. .. . .. .. .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Q-181 

Sandersville, Ga., sections northwest and south of. ............ 48, 68,69 

Santaquin, Utah, dikes near, analyses of rocks similar to ....... 107-108 

dikes near, chemical composition of ... : .. : ..... : ........... 104-106 

classification of.................................. . . . . . . . . . 107 

correlation of ........................................... 108-109 

location and age of.. ....................... .-........... 101-102 

minerals in ............................................. 103-104 

stratigraphy of the vicinity ....... :........................... 101 

structure of the vicinity ........................... · ... ~....... 103 

Saunders, Mr. and Mrs. D. A., fossils collected by .............. 156-157 

Shearer, Harold Kurtz, Cooke, Charles Wythe, and, Deposits of 

Claiborne and Jackson age in Georgia ................ 41-81 

Shell Blufi, Ga., section at ....................................... 6Q-61 

Shellstone Creek, Ga., sections on ................................ 75-76 

Stiver Bluff, Ga., section at...................................... 60 

Slate, exposure of, on Gravina Island, Alaska, plate showing..... 88 

Sloan, Earle, fossils collected by .................................. 5G-51 

Smith, PhilipS., cited ....................................... 94,99-100 

previous work of, on Gravina Island. . . . . . . . . . . . . . . . . . . . . . . . . 83 

Snowcrest Mountains, Mont., principal peak in, plate showing... 116 

section of Quadrant quartzite in. . . . . . . . . . . . . . . . . . . . . . . . .. . . . 116 

Stanton, T. W., acknowledgments to ........................... 130,169 

fossils determined by ....................... 24, 26, 35,92-93,94,96,98 

preface by .................................................. 165-167 

Steiger, George, analyses by ...................................... I, 105 

Stephenson, Lloyd William, A contribution to the geology of 

northeastern Texas and southern Oklahoma ........ 129-163 

work of, on Eocene formations of Georgia..................... 41 

Veatch, Otto, and, cited .................................. 43-44,52 

Stevens Pottery, Baldwin County, Ga., section at................ 71 

Sundance formation, features of.................................. 120 

Sunhill, Ga., section at........................................... 69 

Synentognathi ............ ; .............................. ·..... . 185-186 

T. 

Taff, Joseph A., cited............................................ 151 

work of, in northeastern Texas ............................. 129-130 

Taylor marl, correlation of. .................................... 154-155 

members of ................................................ 155-157 

typical area of ................... ,............................ 154 

Tensleep sandstone, correlation of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 

Teton formation, exposure of..................................... 117 

nature and relation of. ..................................... 113-114 

Texas, northeastern, and Oklahoma, southern, Cretaceous system 

in, formations of. ................................... 134-158 

Page. 

Texas, northeastern, and Oklahoma, southern, faults in.......... 159 

general geology of ...................................... 133-134 

geologic map of part of. . . • . • . . . . . . . . . . . . . . . . . . . . . . . • . . . . • 130 

literature on ........................................... 13Q-131 

oil and gas prospects in ................................ 161-163 

structure of ............................................ 158-161 

summary of report on .................................... · 163 

Tertiary system in, evidence of.. . .. . . .. . . . . . . . . . . . . . . . . . . 158 

topography of. .......• ~ ..... : .......................... 131-133 

Thickness, alinement diagram for computing..................... 126 

Thorn, W. T., jr., work of ... .'............................. 17 

Tivola, Ga., section south of... . . . . . . . . . . . .. . . .. .. .. . . . . . . . . . . . . . 76 

Tivola tongue of the Ocala limestone, distribution of ............. 51,56 

Tomognathidae. ................................................. 184 

Toomsboro, Ga., section west of.................................. 71 

Trinity sand, nature and distribution of. ....••....••..........• 134-135 

plate showing ............ , ................................ .-.. 136 

Turkestan, Cretaceous fish scales from .......................... 179,196 

Twiggs clay member of the Barnwell formation, features of ...••• 52-56 

Twiggs County, Ga., exposures of the Barnwell formation in ....• 73-74 

u.· 

United States National Museum, acknowledgment to............ 169 

University of Kansas, acknowledgment to....................... 169 

Urenchelyidm.. ................................................. 184 

v. 

Vallenar formation, nature and distribution of .................•. 87-88 

V ancouver series, correlation with ................................. 94,97 

Vaughan, T. Wayland, acknowledgments to..................... 1,42 

cited ...................................................... 52,57,60 

fossils determined by ...........................••...... 61,66, 72,77 

Veatch, Otto, work of; on Eocene formations of Georgia.......... 41 

and Stephenson, L. W., cited .................... ~ ......... 43:-44,52 

w. 

Walnut shaly member. See Goodland limestone. 

Warthen, Ga., section south of................................... 69 

Washington County, Ga., exposures of the Barnwell formation in .. 67-70 

Washita group, formations of. ................... : . ............ 138, 144 

lithology and subdivisions of. .............................. 137, 138 

Wave-cut bench, Gravina Island, Alaska, plate showing.. . . . . . . . 88 

Wells, Roger C., New determinations of carbon dioxide in water 

of the Gulf of Mexico................................. 1-16 

Welsh, W. W., samples collected by ............................ . 

Wcno clay member, nature and exposure of...................... 141 

plates showing ............................................. 140, 141 

Western Cross Timbers,. Okla., locality and topography of........ 132 

"White Cliffs chalk." See Annona tongue. 

Wllkii:J.Son County, Ga., exposure of the Baniwell formation in ... 7G-71 

Wilson, M. L., acknowledgment to........................... . . . . 130 

Wolfe City, Tex., section northeast or............................ 155 

Wolfe City sand member of the Taylor marl, nature and exposures 

of..................................................... 155 

calcareous sandstone in, plate showing....................... 154 

Woodbine sand, nature and exposures of ....................... 145-146 

plates showing ............................................. 142,143 

hilly areas underlain by, plates showing ..................... ; 144 

Woodville; Okla., section south of................................ 138 

Woodward, A. S., acknowledgment to........................... 169 

Wrens, Ga., section south of..................................... 66 

Wright, F. E. and C. W., cited................................... 88 

\Vyoming, northwestern, field workin........................... 111 

northwestern, map of, [showing Embar formation............ 112 

west-central, stratigraphy of. .............................. liS, 120 

Y. 

Yellowstone National Park, stratigraphic sections in •• ·.•••••••... 114 

0