DEPARTMENT OF THE INTERIOR

UNITED STATES GEOLOGICAL SURVEY

GEORGE OTIS SMITH, DIRECTOR

352

GEOLOGIC EECONNAISSANCE

OF A

PART OF WESTERN ARIZONA

BY

WILLIS T. LEE

WITH NOTES ON THE

IGNEOUS ROCKS OF WESTERN ARIZONA

BY

ALBERT JOHANNSEN

WASHINGTON

GOVERNMENT PRINTING OFFICE

1908

CONTENTS.

Page.

Introduction.............................................................. 9

Purpose of the investigation.............:.............................. 9

Extent and character of the investigation................................ 9

Summary of previous knowledge....................................... 10

General geography........................................................: 11

Relation to surrounding regions......................................... 11

Topography........................................................... 12

General character................................................. 12

Mountains........................................................ 13

Valleys and plains.................................................. 14

Descriptive geology........................................................ 14

Rock formations........................................................ .1.4

Pre-Cambrian..................................................... 14

Cambrian.......................................................... 15

Carboniferous..................................................... 15

Tertiary... ^...................................................... 16

Eruptive rocks................................................ 16

Greggs breccia................................................ 17

Quaternary........................................................ 17

Temple Bar conglomerate....................................... 17

Chemehuevis gravel............................................ 18

Basalt flows......................;............................. 18

Geographic and geologic details of highlands................................. 18

Grand AYash Cliffs..................................................... 18

Location........:................................................. 18

Topographic features.............................................. 19

Rock masses...................................................... 19

Cottoiiwood and Aquarius cliffs.......................................... 19

Location.......................................................... 19

Topographic features............................................... 20

Rock masses...................................................... 20

Yampai Cliffs.......................................................... 20

Location.......................................................... 20

Topographic features..............................;....,.......-... 20

Rock masses...................................................... 21

Truxton Plateau..................................................'.... 21

Location.......................................................... 21

Topographic features.............................................. 21

Rock masses...................................................... 21

Aquarius Mountains.................................................... 22

Location.......................................................... 22

Topographic features.............................................. 22

Rock masses...................................................... 22 '

3
4 CONTENTS.

Geographic and geologic details of highlands Continued. Page.

Artillery Mountains.".................................................. 22

Location.......................................................... 22

Topographic features.............................................. 22

Rock masses. ..................................................... 22

White Hills.......................................................... 23

Location........................................................... 23

Topographic features.............................................. 23

Rock masses...................................................... 23

Cerbat Mountains..................................................... 23

Location.......................................................... 23

Topographic features.......................................'....... 23

Rock masses...................................................... 23

Structure.......................................................... 24

Hualpai Mountains.................................................... 24

Location.......................................................... 24

Topographic features.............................................. 24

Rock masses...................................................... 25

Structure.......................................................... 25

Aubrey Hills........................................................... 25

Location.......................................................... 25

Topographic features.............................................. 25

Rock masses...................................................... 25

Black Mountains................................:...................... 25

Location.......................................................... 25

Topographic features..........:................................... 25

Rock masses...................................................... 26

Black Mesa............................................................ 26

Location.......................................................... 26

Topographic features.............................................. 26

Rock masses...................................................... 27

Mohave Mountains..................................................... 27

Location.......................................................... 27

Topographic features.............................................. 27

Rock masses...................................................... 28

Harcuvar and Harquahala Mountains.................................... 28

Location.......................................................... 28

Topographic features............................................... 28

Rock masses...................................................... 28

Buckskin Mountains.................................................... 28

Location.......................................................... 28

Topographic features...............:.............................. 28

Rock masses...................................................... 29

Palomas and Dome Rock ranges........................................ 29

Geographic and geologic details of valleys................................... 29

Colorado Valley........................................................ 29

General statement.................................................. 29

Mouth of Grand Canyon........................................... 30

Grand Wash Trough................................................ 30

Haulpai Wash...................................................... 33

Virgin Canyon..................................................... 34

Temple Bar....................................................... 35

Virgin Valley..................................................... 36

Boulder Canyon............ r ............... r ...................... 36
CONTENTS. 5

Geographic and geologic details of valleys Continued. Page.

Colorado Valley Continued.

' ' Las Vegas Wash................................................... 37

Black Canyon..................................................... 37

Cottonwood Valley................................................ 37

Pyramid Canyon................................................... 38

Mohave Valley..................................................... 41

The Needles...................................................... 42

^_ Chemehuevis Valley................................................ 43

Aubrey Canyon. .......^.......................................... 44

Great Colorado Valley.............................................. 45

Chocolate Mountains............................................... ' 46

J Hualpai Valley........................................................ 48

Location and character............................................ 48

Structure.......................................................... 50

Big Sandy Valley...................................................... 50

Location and character............................................ 50

Rock formations.................................................... 51

Structure.......................................................... 51

/ Signal Canyon........................................................ 52

Detrital-Sacramento A^alley............................................. 52

Location and character............................................ 52

Detrital filling.................................................... 53

Williams Valley.....................!.................................. 53

Location and character............................................ 53

Rock formations.................................................... 54

Other valleys........................................................... 55

Location and character... ^......................................... 55

Detrital filling........:........................................... 55

Geologic history............................................................ 56

Introductory statements................................................ 56

Pre-Cambrian conditions............................................... 56

Crystalline rocks................................................... 56

Sedimentation..................................................... 56

Base-leveling..'................................................... 56

Paleozoic and.Mesozoic conditions....................................... 57

Tertiary events........................................................ 57

Explanatory statement............................................ 57

Denudation........................................................ 57

Eruption of andesite............................................... 58

Crustal movements and erosion...................................... 58

Eruption of rhyolite and younger andesite........................... 59

Formation of the Grand Wash Trough............................... 59

^ Deposition of the Greggs breccia.................................... 59

Erosion of the Detrital-Sacramento Valley............................ 60

Relation of Colorado River to the Detrital-Sacramento Valley......... 61

Uplift of the plateau................................................ 61

Effect of uplift on Colorado River.................................. 62

Quaternary (?) events.................................................. 62

First canyon cutting............................................... 62

s Deposition of the Temple Bar conglomerate......................... 63

River diversion.................................................... 64

Second canyon cutting............................................. 65

Deposition of the Chemehuevis gravel.............................. 65
6 CONTENTS.

Geologic history Continued. ' Page.

Quaternary (?) events Continued. . ,

Third canyon cutting............................................... 66

Formation of flood plains........................................... 66

Re'sume of history..................................................... 67

Correlations............................................................ 68

Explanatory statements............................................. 68

Comparison with Lake Bonneville history............................ 68

Comparison with southern California................................. 71 , Comparison with the Pacific coast................................... 71

Comparison with the Plateau region................................ 72

Water supplies............................................................. 74

Surface waters. ....................................................... 74 \,

Precipitation....................................................... 74

Evaporation...................................................... 74

Streams........................................................... 74

Colorado River................................................. 74

Flow........... '.. ........................................ 74

Irrigable lands............................................ 74

Dam sites................................................. 75 v

Big Sandy Wash and Williams River........................... 77

Underground waters................................................... 77

Surface indications................................................. 77

Wells............................................................. 78

Nelson........................................................ 78

Peach Springs.................................................. 78

Hackberj-y..................................................... 78

Kingman..................................................... 78

Gold Basin...................:..........,....................... 78

Drake........................................................ 78

Yucca........................................................ 79

Haviland...................................................... 79

Big Sandy Valley.............................................. 79

Harrisburg..................................................... 80

Other wells. .................................................. 80

Deep-well temperatures............................................. 80

Notes on the igneous rocks of western Arizona, by Albert Johannsen........... 81

Pre-Cambrian crystallines.............................................. 81

Effusive rocks.......................................................... 82

Older andesite..................................................... 82

Rhyolite series.................................................... .83

Younger andesites.................................................. 85

Olivine basalts..................................................... 88

Dike rocks............................................................. 90 >

Olivine diabase.................................................... 90

Rhyolite porphyry................................................. 90

Rock samples from northwestern Arizona................................ 91

Index............:.................................:.................... 93
ILLUSTRATIONS.

Page. 

PLATE I. Sketch map of a portion of western Arizona......................... 9

II. Temple Bar conglomerate at Temple Bar............................. 16

III. A, Signal Canyon, Aquarius Mountains, showing lava-capped gravel

and sand filling; B, Chemeheuvis gravel near Bulls Head......... 22

) IV. A, Rhyolitic ash near Kingman; B, Detritus at the mouth of Deluge

Wash.......................................................... 22

V. Geologic sections ................................................. 24

VI. A, Castl.e-like erosional forms in Black Mesa at Union Pass; B, Basaltf,- . capped gravels in Williams Canyon. ............................ 26

VII. A, North wall of canyon in Grand Wash Trough; B, Mouth of Grand

Canyon........................................................ 30

VIII. A, Temple Bar conglomerate resting.upon older breccia near Temple

Bar; B, Entrance to Black Canyon.............................. 34

. IX. Map and section at south end of Pyramid Canyon, Colorado River... 38 

N X. A, Colorado River and gravel-filled valley at Bulls Head rock; B,

Tilted gravels in Sacramento Wash.............................. 40

XI. Sacramento Valley at south end of Hualpai Mountains............... 52

FIG. 1. Sketch section across White Cliff Canyon.......:..................... 20

2. East-west section across Big Sandy Valley............................ 24

3. Diagrammatic sections across Colorado River at mouth of Grand Canyon

and in Iceberg Canyon........................................... 31

4. Diagrammatic sections across Colorado River near Greggs Ferry, near

Hualpai Wash, and in Virgin Canyon ............................ 34

5. Diagrammatic sections across Colorado River at Temple Bar, at Virgin

River, and in Boulder Canyon..................................... 35

6. Diagrammatic sections across Colorado River near Las Vegas Wash, in

Black Canyon, and at Little Round Island........................... 37

7. Map of a part of the Colorado Valley at the northern end of the Cottonwood Valley..................................................... 38

8. Profiles across Colorado River at the southern end of Pyramid Canyon.. 40

9. Diagrammatic sections across Colorado River at Pyramid Canyon, in the

Mohave Valley, in the Needle Mountains, and at Williams River.... 42

10. Map of Great Bend in Mohave Canyon................................ 43

11. Relations of formations exposed in the Chemehuevis Valley........... 44

12. Map and sections of a part of the Great Colorado Valley................ 46

13. Map of a part of Chocolate Canyon. ................................. 48

14. Sketch section across Big Sandy Wash near mouth of Deluge Wash.... 51

15. Sketch section across Big Sandy Wash at mouth of Trout Creek........ 51

16. Section exposed in the south wall of Williams Canyon................ 54

"' '7

U.S. GEOLOGICAL SURVEY 

GEORGE OTIS SMITH DIRECTOR BULLETIN NO.352 PL. I

114°30' I14-°00' 11330' II3"00'

TOPOGRAPHICAND GEOLOGIC SKETCHMAP 

OF

PORTION OF WESTERN ARIZONA

Compiled from U.S.G.S.topotfraphicmape/location 

maps of the Arizona and California RR.and 

from field surveys/by Willis T.Lee

1I4°SO' 11330'

LEGEND

SEDIMENTARY ROCK

Paleozoic 

f Tonto tmdJRedwaJl)

IGNEOUS ROCKS

Fault
GEOLOGIC RECONNAISSANCE OF A PART OF 

WESTERN ARIZONA.

By WILLIS T. LEE.

INTRODUCTION.

Purpose of the investigation. The investigations described in this 

bulletin were made in western Arizona under the general direction 

of Mr. N. H. Darton. The region examined lies mainly west of the 

high plateau and north of latitude 33° 30'.

The original purpose was to investigate the water resources of the 

region and the extent to which they might be developed. This 

necessitated an examination of the geographic features with special 

reference to irrigable lands and the possibilities of getting water to 

them, and of the geologic formations with reference to their bearing 

on questions of underground water. Conditions were found so unfavorable for water development in this region that the economic results 

of the work are unimportant, or at best have negative value. On 

the other hand, the region proves to be one of great geologic interest. 

Many significant features were observed, and their bearing on important geologic problems was noted, but want of sufficient time as 

well as the desert condition of the region, made it impossible to follow out many of the most interesting lines of investigation.

Extent and character of the investigation. The observations were 

made during rapid reconnaissance trips. In the summer and autumn 

of 1903 the Hualpai, Detrital-Sacramento, Big Sandy, Chino, and 

Aubrey valleys were visited, and Colorado River was examined from 

Needles, Cal., southward to Yuma, Ariz., the object of the river trip 

being to examine the geologic conditions at the various reservoir 

sites of the Reclamation Service along lower Colorado River. During the spring and summer of 1904 a more extended reconnaissance 

was made, including a river excursion from the mouth of Grand Canyon to Needles, Cal., and several overland trips shown on the accompanying map (PI. I).

The amount of territory covered necessitated for the most part 

very general observations, and as the investigation was undertaken

9
10 RECONNAISSANCE OF PART OF WESTERN ARIZONA.

in the interests of water development the evident impossibility of 

development in certain places rendered it impracticable to make 

extended geologic examinations where such examinations would have 

been of great scientific interest. For these reasons the fragmentary 

data here presented might perhaps be of little use if they related to a 

region fairly well known, but so little is known either of the geology 

or of the geography of this region that the information, confessedly 

incomplete, will, it is believed, be of value to many persons.

The northern third of the region is covered by the early reconnaissance maps of the United States Geological Survey, and the geographic 

features are well known. Little has been done, however, toward 

accurately mapping western Arizona south of the thirty-fifth parallel. The maps heretofore published were found erroneous, especially in the locations of mountain groups and lines of drainage. It 

is not claimed that the map accompanying this bulletin is errorless, 

but in the southern part, where previously published maps have 

been most incorrect, this map is believed to be measurably accurate 

owing to data acquired by recent railway surveys and furnished for 

use in this bulletin by W. A. Drake, engineer of the Santa Fe Railway system.

The geologic formations were mapped where practicable, and their 

general distribution over the greater part of the region was determined. Data concerning their character and occurrence were collected as far as time would allow, and special attention was given to 

the recent geologic history.

During the investigation it became evident that changes of a physiographic nature have occurred in recent geologic times, which have 

produced notable results. Changes in surface elevation and configuration and in climatic conditions have resulted in periods of aggradation and periods of degradation during which nearly the entire region 

was affected. The evidences of these changes are found in such 

phenomina as recently formed canyons, filled valleys, aggraded 

plains, and the deflection of streams.

The chief economic results of the examination have to do with the 

development of both surface and underground waters. Attention 

is also called to the mining districts of the region, and certain possibilities of development of the mineral resources are pointed out.

Summary of previous knowledge. Little information has hitherto 

been published regarding the geology of this region. In 1856 Jules 

Marcou's notes were published in the Pacific Railroad Reports,* in 

which he briefly describes the geologic features along the route traversed, including the igneous and granitic rocks of the Truxton Plateau, the detrital filling of the Big Sandy Valley, and the gneiss and

oMarcoii, Jules, Pacific Railroad reports, vol. 3,1856, p. 155.
GENERAL GEOGEAPHY. 11

lava flows in the region of Williams Canyon. Again, in 1858, he 

makes brief mention of the region in his " Geology of North America.""

The first account of any considerable value is found in Lieutenant 

Ives's report on lower Colorado River, published in 1'861. Part 3 

of this report, by J. S. Newberry, describes the geology along the 

route traversed by the Ives expedition. Newberry ascended Colorado River to the mouth of the Virgin, and crossed the northern 

part of the region from Fort Mohave eastward to the Colorado 

Plateau. Later, Major Powell, in the course of his exploration of 

Colorado River, skirted the northern border as far as the mouth of 

the Virgin, and in the early seventies Gilbert and Marvine described 

its northern part in the final Wheeler reports. 6

A few scattered references to the geology of, the region are found 

also in various mining reports. In 1866 c Silliman visited certain 

mines near Fort Mohave, and described in a general way the volcanic

rocks of Black Mesa. In 1863 Blake observed a deposit of iron ore 

near Planet, in Williams Canyon, and described the metamorphic 

strata with which it is associated.d This deposit, together with the 

copper deposits of the Planet district, have recently been described 

by McCarn e in a brief sketch of the geology of that locality, and 

Pratt f has described the occurrence of ore in the Socorro mine, near 

Harrisburg, Ariz.

GENERAL GEOGRAPHY.

RELATION TO SURROUNDING REGIONS.

Arizona is divided into three general geographic provinces,*' known 

as the Plateau, the Mountain, and the Desert regions. The first 

province is well known through the writings of Powell, Gilbert, Dutton, Walcott, and others, as the Colorado Plateau; its western limit 

is very definitely marked in western Arizona by the Grand Wash 

Cliffs. Between the Plateau and. the Desert regions is a mountainous 

belt comprising the second, or Mountain, region, which includes the 

greater part .of the area described in this bulletin. The third, or 

Desert, region is mainly one of low-lying plains with more or less 

isolated mountain groups; it occupies the southwestern part of the 

Territory.

oMarcou, Jules, Geology of North America, 1858, p. 23.

b U. S. Geog. Surv. W. 100th Mer., vol. 3, pts. 1, 2, and 5, 1875.

c Silliman, Benjamin, jr., On some of the mining districts of Arizona: Am. Jour. Sci., 2d ser.,vol. 41, 

1800, pp. 289-308.

d Blake, W. P., Iron regions of Arizona: Idem, vol. 40,1865, p. 388.

« McCarn, H. L., The Planet copper mines (Arizona): Eng. and Min. Jour., vol. 78,1904, p. 20.

/Pratt, J. H., Gold deposits of Arizona: Idem, vol. 73, 1902, p. 795.

ffRansome, F. L., Description of Globe district: Geologic Atlas U. S., folio 111, U. S. Geol. Survey, 

1904, p. 1.
12 RECONNAISSANCE OF PART OF WESTERN ARIZONA.

No definite line of separation can be drawn between the Desert and 

Mountain provinces in the area here described. In central and southern Arizona the distinction is well marked; 0 but in western Arizona 

the Mountain region, so prominent in the central part of the Territory, becomes a transition belt in which the descent of about 6,000 

feet from the high plains of the Colorado Plateau to the low-lying 

plains of the Desert region of southern Arizona is accomplished 

through several mountain groups with gradually diminishing elevation. The transition becomes less marked northward until in northern Arizona the change in elevation is accomplished largely by fault 

scarps.

North of the area described Gilbert, in the Wheeler reports (and 

other geologists following him), makes tut two general provinces, the 

High Plateau and the Great Basin, but states 6 that on account of an 

interlocking of characteristics along the borders their common boundary is not easily located. This division into two topographic provinces is a more natural one for northwestern Arizona than the 

threefold division of central Arizona. The basin ranges and broad 

gravel-filled valleys of Nevada extend southward into Arizona and 

bear the same general relations to the High Plateau that they do in 

southern Nevada and Utah.

TOPOGRAPHY.

General character. The Colorado Plateau here enters into consideration only in so far as it forms the boundary of the area described. 

This bulletin is concerned chiefly with the low-lying area to the west.

In the Mountain region, south of the area described, the rocks have 

been deeply dissected by erosion, and great crustal movements 

have occurred. Near the escarpments bordering the plateau the 

mountains consist in some places of disturbed portions of the sedimentary formations of the plateau, let down to their present position 

by faulting. Mountains of this kind occur in the vicinity of Globe, 

Ariz., c in the Tonto basin, d and within the region described near 

the mouth of Grand Canyon. In many places, especially at a distance 

from the edge of the plateau, sedimentary rocks are not found, and 

it is difficult to determine whether mountains composed entirely of 

crystalline rock are due to local elevation or are simply masses left 

by erosion during the general degradation of the region.

a Lee, W. T., Underground waters of the Salt Eiver valley, Arizona: \Vater-Snpply Paper U. S. 

Geol. Survey No. 13G, 1905.

b Gilbert, G. K., and Marvine, A. R.: U. S. Geog. Surv. W. 100th Her., vol. 3,1875, p. 57.

c Ransome, F. L., Description of Globe district, Arizona: Geologic Atlas U. $., folio 111, U. S. Geol. 

Survey, .1904. Also Geology of the Globe copper district, Arizona: Prof. Paper U. S. Geol. Survey 

No. 12,1903.

d Lee, W. T., Underground waters of the Salt River valley, Arizona: Water-Supply Paper U. S. Geol. 

Survey No. 136,1905, p. 117.
GENERAL GEOGRAPHY. 13

The mountain ranges throughout western Arizona, with a few notable exceptions, lie in general parallel to the border of the plateau. 

In general, also, the mountains become smaller and more completely 

isolated away from the plateau. In central Arizona, where the distinction between mountain and plain is most marked, rugged mountains extend from Mogallon Mesa to the Superstition Mountains, a 

distance of 70 miles, where they give place gradually through such 

isolated groups as the Phoenix Mountains, Estrella Mountains, etc., 

to the still smaller hills of southwestern Arizona. As the mountains 

become less prominent the valleys broaden and finally blend into a 

plain completely surrounding the isolated mountain groups. The 

topographic character of northwestern Arizona lies between these extremes, the area being about equally divided between mountain and 

plain.

Mountains. The mountains of northwestern Arizona occur in four 

more or less distinct groups. The first consists of a series of cliffs at 

the eastern border of the region known as the Grand Wash, Cottonwood, Aquarius, and Yampai cliffs. The first three form a practically continuous escarpment, extending from Colorado River southward to Williams Canyon, a distance of about 125 miles. The Grand 

Wash Cliffs, extending from Colorado River to Music Mountain, a distance of about 50 miles, is composed of crystalline rock at the base, 

overlain by the sedimentary formations of the plateau region. At 

Music Mountain this escarpment divide^, -the lower or crystalline part 

continuing southward under the names of the Cottonwood and Aquarius cliffs and forming the edge of the Truxton Plateau, while the upper 

or sedimentar3r part recedes to the east, under the name of the Yampai 

Cliffs. With the lower group of cliffs may be included the Aquarius 

and Artillery mountains, which form the southward extension of the 

Aquarius Cliffs.

A second group, consisting of the White Hills, Cerbat, and Hualpai 

mountains and the Aubrey Hills, forms a broken range parallel to 

the cliffs at the west. The White Hills and the Aubrey Hills are inconspicuous as topographic features, but the two central sections are 

prominent. The Hualpai Mountains attain a maximum altitude of 

8,266 feet in Hualpai Peak, and the Cerbat Mountains an altitude of 

somewhat more than 7,000 feet in Cherums Peak.

A third group, lying still farther to the west, is commonly known 

as the Black Mountain Range, and consists of the Black Mountains 

proper, Black Mesa, and the Mohave Mountains. This range is relatively low, except at its northern end, but is continuous from Colorado River southward to Sacramento Wash, where it is broken down 

for a few miles before attaining prominence again in the Mohave 

Mountains.
14 RECONNAISSANCE OF PART OF WESTERN ARIZONA.

The fourth group of mountains, situated south of Williams River, 

does not correspond with the other three groups in geographic position or in regularity of arrangement. In place of the parallel arrangement of north-south ridges just described, this group is made, up 

of three large east-west ranges and three small north-south ranges. 

The Harcuvar and Harquahala mountains are about equal in altitude 

and are the loftiest and most massive mountains in central western 

Arizona. The other groups are less conspicuous, though the Buckskin Mountains are moderately prominent, particularly at their eastern extremity.

 Valleys and plains. Three distinct kinds of lowland occur: First, 

the valleys and canyons now containing running water, such as the 

Colorado and Williams valleys, including Big Sandy Wash and Santa 

Maria Canyon; second, old debris-filled valleys, such as the DetritalSacramento, Hualpai, and Big Sandy valleys; and third, plains eroded 

from hard rock or built up by flows of igneous rock, such as the Truxton Plateau. Extensive detrital plains, such as Cactus Plain, Ranegras Plain, etc., which occur south of Williams River, are probably 

debris-filled valleys similar to those farther north, but their character 

is not certainly known.

DESCRIPTIVE GEOLOGY.

ROCK FORMATIONS.

The rocks of western Arizona are mainly pre-Cambrian crystallines, 

Tertiary eruptives, and probably Quaternary sediments. Sedimentary formations of Paleozoic age occur only at the eastern margin of 

the area described. The igneous rocks are described by Albert Johannsen (see pp. 81-92), but many of the details upon which this general 

description is based may be found in the following sections.

PRE-CAMBRIAN.

The oldest rocks of the region consist mainly of granites and 

gneisses. (See p. 81.) Coarse-grained granitic rock giving little or 

no evidence of gneissoid structure is found in many places throughout 

northwestern Arizona. It occurs beneath the Cambrian sandstone 

at the base of the cliffs in the eastern part of the region, forms the 

central core of the Black Mountains, and constitutes the main mass 

of the Cerbat and Hualpai mountains. Gneiss occurs in many places, 

either in extensive masses, as at the southern end of the Hualpai 

Mountains and in the Aubrey Hills, or in restricted areas where local 

movements have taken place, as near Hualpai Wash, at the northern 

end of the region. At the mouth of the Grand Can}~on the granite, 

which had obviously been exposed at the surface prior to the deposition of the Cambrian sediments, is prevailingly red to a depth of
DESCRIPTIVE GEOLOGY. 15

200 feet or more. A similar coloring of both the granite and the 

gneiss was noted in Black and Boulder canyons and in several places 

south of Williams Kiver.

Metamorphosed sediments, consisting of quartzites, argillites, and 

limestones, occur in several localities in northwestern Arizona. These 

were observed in Virgin Canyon at the northern end of the region, in 

Williams Canyon, and in the Granite Wash Hills in the vicinity of 

Harrisburg. They are highly metamorphosed, faulted, tilted, and 

more or less included as blocks within the granites and gneisses. They 

were nowhere observed in contact with the Cambrian, but on account 

of their high degree of metamorphism and their intimate association 

with granites which, in the cliffs region, lie beneath the Cambrian 

sandstone, are here regarded as probably pre-Cambrian rocks.

CAMBRIAN.

According to the various writers who have described the Grand 

Canyon region, Cambrian rocks occur in Grand Canyon and are 

identical in character with those in the cliffs in the eastern part of the 

area described. They consist of a coarse-grained basal quartzite 80 

to 100 feet thick, overlain by about 600 feet of yellowish-green 

arenaceous shale. The quartzite and shale together comprise the 

greater part of the Tonto formation of the Grand Canyon section.

CARBONIFEROUS.

Resting with apparent conformity upon the Tonto formation is the 

Redwall limestone (the Devonian of Grand Canyon described by 

Walcott a was not identified in the cliffs), which is 1,000 feet or more 

in thickness where examined. 6 From Music Mountain southward 

this limestone is separated more or less distinctly into an upper and 

a lower division. The upper part is massive, with little tendency 

toward separation into layers even in weathered surfaces. The 

lower part, although consisting mainly of limestone, is made up of 

distinct layers, often separated by thin seams of clay.

In Truxton Canyon two small collections of fossils were obtained 

from the Redwall limestone. These were examined by G. H. Girty, 

of the Geological Survey, who reports the following lists.

At Yampai, near the top of the exposed section, the following were 

obtained:

Derbya? sp.

Composita aff. C. subtilita. 

Aviculipecten sp. 

Aviculipecten sp.

Aviculipecten sp.

Myalina sp. aff M. raeliniformis and M.

congeneris. 

Eclmondia? sp.

"Walcott, C. D., Am. Jour. Sci., 3d ser., vol. 20, 1880, pp. 221-225.

l> G. K. Gilbert's section at the mouth of Grand Canyon shows a thickness of 2,075 feet in the Redwall. 

limestone.
16 RECONNAISSANCE OF PART OF WESTERN ARIZONA.

These fossils, according to Girty, indicate a Pennsylvania!! or "Coal 

Measures' 5 age.

Lower in the section, near Nelson, Ariz., Mississippian forms were 

obtained as follows:

Menophyllum excavatuin. 

Schuchertella inaequalis.

Spirifer striatus var. madisonensis. 

Straparollus sp.

Spirifer centronatus.

Girty states that this is the Eomississippian fauna, which has a wide 

range over the West, correlating with the lower a Wasatch" a limestone of Utah, the Madison limestone of Yellowstone Park, and the 

Chouteau limestone of Missouri.

The Red wall limestone has been described by Gilbert 6 as consisting 

of "Upper Carboniferous" above and "Lower Carboniferous" below, 

and King 0 makes a similar division of the "Wasatch" limestone in 

Utah. It is probable that in the area here described the line of 

separation between the Pennsylvanian and the Mississippian is to be 

drawn between the upper massive and the lower laminated divisions 

of the Redwall.

TERTIARY.

Eruptive rocks. If sediments of Triassic, Jurassic, or Cretaceous 

age were deposited in western Arizona, they were removed previous 

to the opening of the Tertiary period. 'The Tertiary rocks are principally effusive andesites and rhyolites, which occur in isolated mountain masses and in broad sheets having a maximum thickness of 3,000 

feet or more. The oldest effusive rock is the andesite of the northern 

end of Black Mesa. (See p. 27.) It is a dark-colored porphyritic 

rock lying above the granite and beneath the rhyolites and later 

andesites.

The older andesite is overlain by extensive beds of rhyolitic ash, 

tuff, and flows, which extend over a large part of western Arizona, and 

which were in turn followed by extrusions of andesite. The rhyolites 

and younger andesites are closely associated and must at present be 

described together. (See pp. 83-87.) They are conspicuously exposed 

in the Black Mesa, White Hills, Kingman Mesa, and Aquarius Mountains, but extend eastward beyond the area mapped, and farther south 

occur in extensive masses in the Chocolate and Dome Rock ranges.

Some of the older basalt sheets of the region may also belong to the 

Tertiary, but this is not definitely known. They cut the rhyolites and 

andesites in dikes and overlie them in sheets^ East of Chloride they

a Present usage of the Geological Survey restricts the name Wasatch to the Eocene formation. As 

soon as sufficient detailed work can be done, another name will be assigned to the Carboniferous formation.

b Gilbert, G. K., Final Kept. U-. S. Geog. Surv. W. 100th Mer., vol. 3,1875, pt. 1, p. 178.

o King, Clarence, Final Kept. U. S. Geol. Explor. 40th Par., vol. 1, p. 155.
U. S. GEOLOGICAL SURVEY BULLETIN NO. 352 PL, II

TEMPLE BAR CONGLOMERATE AT TEMPLE BAR.
DESCBIPTIVE GEOLOGY. 17

occur within the Detrital-Sacramento Valley, which was presumably 

excavated in late Tertiary time.

Greggs breccia. The Greggs breccia, so called from Greggs Ferry, 

at the northern end of the region, is a name here given to a detrital 

formation filling the Grand Wash Trough and having an exposed 

thickness of about 1,400 feet. It is composed of coarse unassorted 

and poorly stratified material, consisting largely of blocks of crystalline rock, similar to the granite and gneiss of the Virgin Mountains 

to the west. Toward its top the detrital material is cemented with 

lime carbonate, and in places the upper 200 feet consists of travertine 

containing few rock fragments. This travertine is best exposed 

south of Colorado River and east of Greggs Ferry, where it caps 

conspicuous cliffs, which rise 1,400 feet or more above the river.

The formation contains no fossils, so far as observed, and its reference to the Tertiary is based largely on the physiographic evidence 

given in detail in the description of the Grand Wash Trough and later 

in the section on "Geologic history." Briefly stated, the accumulation of the breccia antedates the cutting of Grand Canyon, which 

apparently began either in the latter part of the Tertiary or at the 

beginning of the Quaternary.

QUATERNARY.

Temple Bar conglomerate. Temple Bar conglomerate is a name here 

given to a sand and gravel formation having wide distribution in western Arizona. It occurs in the Colorado and other valleys of that 

region, filling the low places generally to an altitude of 3,000 feet or 

more. The conglomerate is typically exposed near the mouth of 

Virgin River at Temple Bar, from which it takes its name. At this 

point it consists of slightly consolidated sand and gravel exposed in 

nearly perpendicular cliffs (PL II), in which are included sheets of 

basalt.

Where exposed along the Colorado, the Temple Bar conglomerate 

is evidently a river deposit, but it merges laterally into deposits of 

angular mountain wash in some places, and possibly into lacustrine 

deposits in others. It rests unconformably upon the Greggs breccia 

and older formations, and is apparently equivalent in age to the widespread detrital accumulation filling the low places of the Southwest 

generally and forming the desert plains of Arizona and parts of southern California.

No fossils have been found in the conglomerate, and there are no 

means known at the present time by which it may be definitely correlated with other formations. In composition, geologic and physiographic relations, and general appearance it is similar to the Gila

49964 Bull. 352 08 2
18 BECONNAISSANCE OF PAKT OF WESTEEN ARIZONA.

conglomerate described by Gilbert a from the Gila Valley; by Ransome 6 from the vicinity of Globe, Ariz.; by Lindgfen c from eastern 

Arizona, and by the present writer d from the Salt River Valley in 

central Arizona. The greater part of the Temple Bar conglomerate, 

however, is not usually so well consolidated as the Gila conglomerate, 

although in places, especially where the older portions are exposed, 

it is as firmly cemented.

In constitution and general appearance the formation resembles 

the Lake Bonneville beds of Utah described by Gilbert e as Quaternary. The correlation, however, is based mainly on physiographic 

evidence, the discussion of which is included under "Geologic history," and, for the sake of clearness, is placed after the section on 

descriptive details.

CJiemehuevis gravel. Chemehuevis is here applied to a series of 

gravels that lie unconformably upon the Temple Bar conglomerate 

in the terraced bluffs along Colorado River from Grand Canyon to 

the Gulf. In the open valleys south of Black Canyon they form the 

conspicuous bluffs seen in characteristic development from Bulls 

Head southward. The name is derived from the Chemehuevis 

Valley, south vof The Needles. The gravels are about 700 feet in 

maximum thickness, but occupy a measurably narrow belt along 

the river, having been deposited as valley filling during an aggrading 

stage of Colorado River. (See p. 65.) Their unconformable relations 

with the Temple Bar conglomerate and their unconsolidated condition 

render it probable that they are of late Quaternary age.

Basalt flows. Included in the Temple Bar conglomerate in many 

places, and sometimes overlying that conglomerate, are sheets of 

basalt from a few feet to 800 feet in thickness, in some places occupying large areas. These are younger than the basalts which were 

described on page 16 as having perhaps been outpoured at the close 

of the Tertiary and which underlie the Temple Bar conglomerate.

GEOGRAPHIC AND GEOLOGIC DETAILS OF HIGHLANDS.

GRAND WASH CLIFFS.

Location. The Grand Wash Cliffs, located in the northeastern 

part of the area described, form an escarpment extending from 

Music Mountain northward beyond Colorado River. They constitute 

the boundary between the High Plateau or Grand Canyon district to 

the east and the low-lying Basin region to the west.

a Gilbert, G. K., U. S. Geog. Surv. W. 100th Mer., vol. 3, pt. 5,1875, p. 540.

6 Ransome, F. L., Geology of Globe copper district, Arizona: Prof. Paper U. S. Geol. Survey No. 12, 

1903, pp. 47-51.

c Lindgren, Waldemar, The copper deposits of the Clifton-Morenci district, Arizona: Prof.> Paper 

U. S. Geol. Survey No. 43, 1905, pp. 75-77.

d Lee, W. T., Underground, waters of the Salt River Valley, Arizona: Water-Supply Paper U. S. Geol. 

Survey No. 136,1905, pp. 111-114.

« Gilbert, G. K., Lake Bonneville: Mon. U. S. Geol. Survey, vol. 1,1890. 
DETAILS OF HIGHLANDS. 19

Topographic features. The Grand Wash Cliffs are very precipitous, 

as shown in section P-P', PI. V, rising 4,000 feet or more above the 

plains to the west. The drainage of the plateau near the cliffs is 

northward to Colorado River, and the continuity of the westwardfacing escarpment is broken by few canyons.

The lower or granitic portion of the cliffs, though not so nearly 

perpendicular as the upper or limestone portion, is steep, and the 

slopes meet the detrital surface of the Hualapai Valley at high angles. 

Numerous detrital cones have formed at.the foot of the escarpment, 

but they are comparatively small. Iii a few places the cones join 

laterally, forming an alluvial slope, but. in general the escarpment 

rises abruptly from the nearly level floor of the valley.

Rock masses. At the mouth of Grand Canyon the cliffs are composed principally of Carboniferous limestone (Redwall) and Cambrian sandstone and shale (Tonto), with a little granite exposed at 

the base. In Music Mountain, at the southern end of the Grand 

Wash Cliffs, the same series occurs, but the granite is more extensively exposed, the base 'of the Tonto being about 4,000 feet higher 

than at the mouth of Grand Canyon.

The granite is coarse grained and is intersected by dikes and 

sheets of intrusive rocks which terminate abruptly at the contact 

between the granite and the overlying sandstone of the Tonto. This 

contact, as-seen in the face of the escarpment, is a practically straight 

line and represents a base-leveled surface upon which the Cambrian 

sediments were deposited.

The sandstone at the base of the Tonto at the mouth of Grand Canyon is 80 feet thick and the overlying shale is about 600 feet thick. 

About 12 miles southwest of the mouth of the canyon, at the base 

of the tilted block through which Iceberg Canyon is cut, the sandstone is again 80 feet thick, but the overlying shale is only 200 feet. 

A few miles north of Music Mountain, in the pass occupied, by the 

road from the Hualpai Valley to the plateau, the sandstone was 

found to be 50 feet thick and the overlying shale 300 to 400 feet thick.

The Devonian of the Grand Canyon region, described by Walcott,a 

was not identified by the writer in the Grand Wash Cliffs. The 

highest formation observed was the Redwall limestone, which forms 

the rim of the cliffs, and though more or less eroded, still has a thickness of 1,000 feet or more, according to locality.

COTTONWOOD AND AQUARIUS CLIFFS. '

Location. At Music Mountain the escarpment divides, the upper 

or sedimentary part receding toward the east and the lower or granitic 

part continuing southward under the names of the Cottonwood and 

the Aquarius cliffs. The Cottonwood Cliffs extend from Music

a Walcott, C. D., Am. Jour. Sci., 3d ser., vol. 20,1880, p. 222.
20 RECONNAISSANCE OF PART OF WESTERN ARIZONA.

Mountain to Trout Creek, and are best observed in Truxton Canyon, 

through which the Santa Fe Railway descends from the high plateau 

to the lowlands farther west. The Aquarius Cliffs extend from 

Trout Creek southward to the Aquarius Mountains.

Topographic features. The Cottonwood and the Aquarius cliffs 

are lower and less precipitous than the Grand Wash Cliffs. Alluvial 

cones and slopes are developed to some extent at the base of the 

Cottonwood Cliffs north of Truxton Canyon, but from that canyon 

southward to Signal the Big Sandy flows close to the cliffs and 

prevents the formation of cones.

The continuity of the escarpment formed by these cliffs is interrupted in several places by canyons, chief among which are Truxton, 

White Cliff, Trout, and Sycamore creeks. The canyons are narrow 

and steep and the streams torrential in character.

Rock masses. The Cottonwood Cliffs are composed principally of 

granite, 2,500 feet of which is exposed near Hackberry. The granite 

is covered by a comparatively thin sheet of andesite which forms the 

cap rock of the cliffs and thickens southward, connecting with the 

great masses of igneous rock in the Aquarius Mountains.

WHITE CLIFF CANYON

Vz

FIG. 1. Sketch section across White Cliff Canyon, showing relation of the andesite of the Truxton 

Plateau, to the younger basalt at the foot of the cliff. 1, Andesite flow; 2, granite; 3, andesite tuff; 

4, basalt flow; 5, stratified volcanic ash.

In White Cliff Canyon the plateau is covered by andesite 200 feet 

thick, the lower half consisting of tuff and the upper half of a columnar

flow. Near the mouth of .the canyon a younger mass of volcanic 

rock occurs in an erosion embayment about 1,200 feet lower than 

the lava capping the cliffs. The younger mass is basalt and consists 

of several layers of ash, tuff, and flow. (See fig. 1.)

YAMPAI CLIFFS.

Location. A series of irregular cliffs extends from Music Mountain 

in a general southeasterly direction to the southern end of the Juniper 

Mountains, where they turn northward, forming the western bluffs 

of the Chino Valley, which lies directly east of the area here described. 

These are locally known as the Yampai Cliffs.

Topographic features. The Yampai Cliffs resemble the Grand Wash 

Cliffs in being precipitous and composed of hard limestone strata, 

but differ from them in being much more irregular in outline. They 

vary in altitude from about 6,000 to 6,700 feet and rise 1,000 or 

more feet above the Truxton Plateau. In their sinuous outlines, 

large reentrant angles, and detached outlying portions Yampai
DETAILS OF HIGHLANDS. 21

Cliffs exhibit the characteristic features of an erosion escarpment, 

the steep face being maintained by the hard Kedwall limestone at 

the top.

Rock masses. Pre-Cambrian granite occurs in the base of the 

cliffs. It was observed by the writer in four localities at Music 

Mountain, in Truxton Canyon, near Cross Mountain, and at the 

southern end of the Juniper Mountains. As in the Grand Wash 

Cliffs, it terminates above in a base-leveled plain, upon which the 

Cambrian sediments rest.

- The Cambrian rocks described continue uninterruptedly southward from the Grand Wash Cliffs, the basal sandstone being about 

100 feet and the shale about 225 feet thick at the southern end of the 

Juniper Mountains.

The Redwall limestone continues southward as the highest formation of the cliffs, and on account of its superior hardness maintains 

the precipitous face. It thins southward, probably owing to erosion, 

until at the southern end of the Juniper Mountains it is only 450 

feet thick.

The section near Nelson, in Truxton Canyon, yielded the fossils 

previously described, showing that the Redwall limestone is partly 

of Mississippian and partly of Pennsylvanian age. Although examined with considerable care, no fossils were'found in the limestone 

at the southern end of the Juniper Mountains.

TRUXTON PLATEAU.

Location. Lying between the Yampai Cliffs on the east and the 

Cottonwood and Aquarius cliffs on the west, is a comparatively level 

plain extending from Music Mountain southward to the Aquarius 

Mountains. The writer crossed it in two places near the northern 

end, as shown by the routes of travel delineated on PI. I. In the 

vicinity of Truxton Canyon it is locally known as the Truxton Plateau, 

and this name may be used to designate the entire area.

 Topographic features. The plateau, which lies about 5,000 feet above 

sea level, consists of eroded granite, nearly covered with eruptive 

rock, which fills the depressions, leaving the higher granite points 

exposed above the lava. In other words, the Truxton Plateau is a 

lava-covered peneplain which has been slightly dissected by a few 

streams that have cut narrow canyons. Back from the edge of the 

plateau these are shallow, but they deepen rapidly as they near the 

cliffs to the west, a fact indicative of comparatively recent uplift.

Rock masses. The rocks of the plateau are .pre-Cambrian granites 

overlain by Tertiary rhyolite and andesite, together with basalt of 

more recent origin. The plateau was not visited south of Trout 

Creek, but, seen from a distance, the igneous rock apparently extends 

continuously southward to the great masses of rhyolite and andesite 

of the Aquarius'Mountains.
22 RECONNAISSANCE OF PART OF WESTERN ARIZONA. 

AQUARIUS MOUNTAINS.

Location. The Aquarius Mountains, located in the east-central part 

of the region, form a group of considerable size at the southern end of 

the Truxton Plateau, and extend in a southeasterly direction across 

the course of Rio Santa Maria and Date Creek.

Topographic features. South of the mouth of Deluge Wash the 

Aquarius Cliffs gradually lose their scarplike character and finally 

merge into the general westward slope of the Aquarius Mountains. 

These mountains were visited only at their southern and western 

extremities, but from the west at a distance they appear as loft}7" 

mountains, comparable in altitude with the Hualpai Mountains to the 

west, and the Harcuvar and Harquahala mountains to the south.

The southern part of the group is carved into rugged, irregular 

hills. Rio Santa Maria has eroded a narrow canyon deep into the 

lavas, and smaller streams have cut less deeply. Date Creek has cut 

through the end of the ridge, instead of following an apparently easy 

course a few miles farther south.

Rock masses. The granite of the Truxton Plateau extends southward to the Aquarius Mountains, and was examined in Signal Canyon. 

The southern part of the group, however, is composed of andesites and 

rhyolites, presumably of Tertiary age. South of Santa Maria Canyon 

the mountains, 3,000 to 4,000 feet high, are composed of effusive rock, 

which has been dissected by erosion to a depth of about 3,000 feet.

Within valleys eroded in the Tertiary lavas small sheets of basalt 

occur, in some places capping gravels of probable Quaternary age, as 

in Signal Canyon (PL III, A), and in other places occurring within 

these gravels, as in Santa Maria Canyon near the' mouth of Big 

Sandy Wash.

ARTILLERY MOUNTAINS.

Location. The Artillery Mountains form a small group near the 

head of Williams River. They are separated from the Aquarius 

Mountains by Signal Canyon only, and are virtually an outlying 

group of those mountains.

Topographic features. The Artillery Mountains are small and comparatively low, the only conspicuous peak being a sharp pinnacle of 

igneous rock, apparently a volcanic neck, which, on account of its 

altitude and pointed summit, is visible and easily identifiable from 

great distances. The rocks are deeply dissected by erosion on the 

east and south near Big Sandy and Williams rivers, but to the north 

and west the mountain flanks are buried by the detritus of the Big 

Sandy Valley.

Rock masses. The main rock mass of the Artillery Mountains is 

coarse-grained granite, mineralized in places, although the mineral
U. S. GEOLOGICAL SURVEY BULLETIN NO. 352 PL. Ill

*$&?

A. SIGNAL CANYON, AQUARIUS MOUNTAINS. 

Showing lava-capped gravel and sand filling.

H, CHEMEHUEVIS GRAVEL NEAR BULLS HEAD. 

Overlying granite at left. Showing upper and lower divisions of gravel.
U. S. GEOLOGICAL SURVEY ULLET1N NO. 352 PL. IV

A. RHYOLIT1C AbH NEAR KINGMAN.

11. DETRITUS AT MOUTH OF DELUGE WASH.
DETAILS OF HIGHLANDS. 23

prospects have not been extensively developed owing to the inaccessibility of the region.

Overlying the granite south of Artillery Peak occur thick masses 

of effusive rock similar in appearance to the older effusives of the 

Aquarius Mountains to the east, but separated from them by erosion. 

Quaternary lavas also occur in small quantities included in and overlying the gravels in Signal and Williams canyons.

WHITE HILLS.

Location. The White Hills, located in the north-central part of the 

region described, are the southward continuation of the Virgin Mountains of southeastern Nevada, and are separated from them by Virgin 

Canyon.

Topographic features. The White Hills consist of many more or 

less isolated peaks and groups of hills rising a few hundred feet above

the plains on either side of them, and are inconspicuous as compared 

with neighboring highlands.

Rock masses. Granite similar in general appearance to that 

beneath the Cambrian formation of. the Grand Wash Cliffs occurs in 

these hills, and is more or less mineralized, several gold prospects having been developed in it. Quartzites and argillites, apparently of 

pre-Cambrian age, occur in the hills south of Virgin Canyon. The 

Tertiary rhyolites and andesites are found from Squaw Peak to the 

southern end of the White Hills, and occur as light-colored beds of 

tuff and ash and as flow sheets.

CERBAT MOUNTAINS.

Location. The Cerbat Mountain range, about 30 miles long, lies 

south of the White Hills, between the Hualpai arid the DetritalSacramento valleys.

Topographic features. The mountains are high, attaining a maximum altitude of about 7,000 feet in Cherums Peak, and have been 

deeply eroded. At the southern end of the range they break down 

and merge into a dissected plateau.

Rock masses. The Cerbat Mountains are composed mainly of 

granitic rock similar in general appearance to the pre-Cambrian granites of the cliffs region to the east. These are intersected and more 

or less completely surrounded by effusive rocks.

Along the western base of the range rhyolite and andesite occur at 

intervals, but are frequently eroded away or covered with wash. 

Near the southern end of the mountains they overlie the granite in 

extensive beds of ash, tuff, and flow, originally 1,000 feet or more in 

thickness. The igneous rocks are evidently due to a long series of 

eruptions, flows, and beds of tuff alternating (see PI. IV, A), and both 

being cut by dikes and covered by younger effusives.
24 RECONNAISSANCE OF PART OF WESTERN ARIZONA.

These effusives are megascopically and microscopally the same as 

the rhyolites and younger andesites of Black Mesa to the west, and 

form a part of the lava sheet supposed to have once extended continuously across the Detrital-Sacramento Valley. At the northern 

end of the range sheets of olivine basalt occur at the crest of the ridge, 

tilted eastward. (See section Q-Q', PL V.) In severaf places along the 

eastern base similar sheets occur, dipping steeply to the east and 

passing beneath the detrital filling of the Hualpai Valley.

Structure. The eastward inclination of the lava sheets along the 

eastern base of the Cerbat Mountains suggests an eastward tilting of 

the surface similar to that shown in Iceberg Canyon to the north and 

in the Hualpai Mountains to the south (fig. 2).

HUALPAI MOUNTAINS.

Location. The Hualpai Mountains are situated between the Sacramento Valley on the west and the Big Sandy Valley on the east, in 

the central part of the area described.

Aquarius Cliffs

Horizontal scale Vertical scale 

o i za-ts miles o 5000 loooofeet

FIG. 2. East-west section across Big Sandy Valley, snowing the tilted Hualpai block and the unconsolidated gravel beds inclined toward the lace of the Aquarius Cliffs. 1, Chemehuevis(?) gravel; 

2, granite; 3, Temple Bar (?) conglomerate; 4, andesite.

Topographic features. The range is about 35 miles long, with a 

general altitude of about 7,000 feet and a maximum altitude of 8,266 

feet, attained in Hualpai Peak. The western slope is very precipitous 

down to an altitude of about 3,000 feet, where it meets the detrital 

plain of the Sacramento Valley at high angles. Along its base occur 

small flat-topped lava-covered hills, rising a few hundred feet above 

the surrounding plain. These are most numerous at the north, near 

the lava fields of the Kingman area, but extend southward nearly to 

the southern end of the range. Detrital material has accumulated 

in alluvial fans and slopes to some extent, but in general the steep 

mountain face meets the plain at high angles.

The eastern slope of the mountains is not so precipitous as the 

western. At altitudes of nearly 6,000 feet the crystalline rocks begin 

to disappear beneath a corrugated detrital slope of comparatively low 

gradient, which extends eastward to Big Sandy Wash, a distance of 

10 to 15 miles. In this distance the descent is about the same as that 

attained in the western slope in a much less distance. (See fig. 2.)

At the southern end of the range the mountains cease rather 

abruptly, giving place to low isolated hills separated by broad passes 

occupied by the detrital accumulation of the plains. To the east are 

several comparatively small spurs 'and detached mountain groups, 

such as Owens Peak, Peacock Mountains, etc.
U. S. GEOLOGICAL SURVEY BULLETIN NO. 352 PL. V

Detrital-Sacrament 

Valley

_ _____

^iii^liiES;?^?.^;;'1:^;?^

Detrital-Sacramento 

Valley

Harcuvar Mts. ' Harquahala Mts. 

Cactus Plains x*"?>-^ McMullen Valley

SEDIMENTARY ROCKS IGNEOUS ROCKS

Temple Bar conglomerate 

and Chemehuevis gravels

Greggs breccia Paleozoic sediments Basalt Rhyolite and andesite Granite and gneiss

Horizontal scale in miles 

0 5 10

Vertical scale in feet

10000 O IOOOO 2000O

GEOLOGIC SECTIONS. FOR LOCATION SEE PL. I.
DETAILS OF HIGHLANDS. 25

Rock masses. The Hualpai Mountains, so far as observed, are composed mainly of coarse-grained granitic rock, becoming gneissoid at 

the southern end of the range. They are highly mineralized in places, 

and dikes and quartz veins are numerous. At Cedar, near the summit of the range, mining operations have been successfully carried on 

for a number of years. The lavas capping the foothills to the west 

are outlying portions of rhyolites and andesites of the Kingman area 

(see p. 16), and the small masses in the Peacock Mountains are probably parts of the lavas covering the Truxton Plateau that have been 

let down to their present position by faulting. The detrital material 

of the eastern slope is part of the detrital accumulation described 

under the caption ' ( Big Sandy Valley.''

Structure. The Hualpai Range was apparently formed by the 

upheaval and tilting eastward of a large crust block, the movement 

taking place along faults west of the range and at the Cottonwood and

Aquarius cliffs. The evidence of block tilting in addition to that 

given of faulting along the cliffs rests on the steep, scarplike western 

face of the range, the high angles at which the mountain slope meets 

the surface of the Sacramento Valley, and the gently inclined debris 

slope of the eastern face.

AUBREY HILLS.

Location. South of the Hualpai Mountains and lying between the 

Sacramento and Big Sandy valleys is a small group known as Aubrey 

Hills.

Topographic features. The Aubrey Hills are low, rising but a few 

hundred feet above the plains on either side. They are separated 

from the Hualpai Mountains by a low debris-filled pass connecting 

the Big Sandy and the Sacramento valleys, and from the Buckskin 

Mountains by Williams Canyon.

Rock masses. The rock at the northern end of the hills is granitic 

gneiss. In Williams Canyon occurs similar gneiss overlain by quartzite, argillite, and black metamorphic limestone. From a distance 

sheets of effusive rock were noted east of the hills, and dark-colored 

lava, probably basalt, was seen on their western flanks.

BLACK MOUNTAINS.

Location. The Black Mountains, located in the extreme western 

part of Arizona, extend from the northern border of the Territory 

southward to Union Pass.

Topographic features. The mountains are formed of three more or 

less distinct groups. The northernmost group, extending from 

Boulder Canyon southward to Eldorado Pass, a distance of about 15 

miles, attains a maximum altitude of about 5,500 feet in Mount Wilson. From this peak the altitude diminishes northward to about
26 KECONNAISSANCE OF PART OF WESTEEN ARIZONA.

3,000 feet at Boulder Canyon, and southward to about 2,000 feet at 

Eldorado Pass.

Mount Perkins, 5,500 feet high, is the center of the second group, 

which consists of a north-south ridge about 30 miles long. The 

third or southernmost group, about 4,500 feet in maximum altitude, 

consists of many small irregular hills extending eastward for a considerable distance into the Detrital-Sacramento Valley. The three 

groups form a continuous range, the apparent separation being due 

to accumulation of detritus, which fills the old valleys and covers the 

low-lying passes.,

Rock masses. The core of the Black Mountains consists of granitic 

rock. In Boulder Canyon coarse-grained crystalline rock occurs, as 

described by Gilbert," overlain on either side by gneiss. In Pyramid 

Canyon, farther to the south, and in the hills east of this canyon the 

rock is granitic gneiss.

The older crystalline rocks of the range are overlain by extensive 

masses, of effusive rock representing several periods of eruption. The 

oldest of the effusives, the andesite of the Gold Roads region, was not 

observed in Black and Boulder canyons, but in many places rhyolites 

and light-colored andesite similar to those overlying the dark-colored 

andesite of Gold Roads (see p. 27), rest upon the granites and 

gneisses. These are especially prominent in Black Canyon, where 

they are many hundreds of feet thick. . They were observed near 

the river at the head of the Cotton wood Valley (section K, fig. 6), at 

the head of Pyramid Canyon, and at many places in the Black 

Mountains up to an altitude of 3,000 feet or more.

The next younger effusive rocks of the Black Mountains are basalts. 

They occur in dikes cutting the older rocks and in sheets overlying 

the rhyolites and younger andesites. North of Union Pass they 

were outpoured in the Detrital-Sacramento Valley, which had previously been eroded through the rhyolites and younger andesites.

BLACK MESA.

Location. Black Mesa, about 35 miles long and 5 miles or more 

in width, is situated between the Colorado and the Sacramento valleys, in the central western part of the area described.

Topographic features. The mesa is a remnant of a once extensive 

plateau having a general altitude of about 4,000 feet and a maximum 

at Mount Nutt of about 5,000 feet. A large part of the plateau has 

been eroded away and the remaining part deeply dissected by erosion. 

The bordering cliffs, although deeply incised, form a comparatively 

regular escarpment at the eastern margin of the mesa, rising 1,000 

feet or more above the floor of the Sacramento Valley. The western 

margin is much more irregular owing to the greater erosion caused by

a Gilbert, G. K,. Final Kept. U. S. Geol. Surv. \V. 100th Mer., vol. 3,1875, pt. 2, p. 35.
U. S- GEOLOGICAL SURVEY BULLETIN NO. 352 PL. VI

A. CASTLE-LIKE EROSIONAL FORMS IN BLACK MESA AT UNION PASS.

B. BASALT-CAPPED GRAVELS IN WILLIAMS CANYON.
DETAILS OF HIGHLANDS. 27

the downcutting of Colorado River. On this side are many more or' 

less isolated outlying remnants of erosion, well shown on The Needles 

special map of the United States Geological Survey, which includes 

a small part of the southern end of Black Mesa (there called Ute 

Mountains). The most conspicuous of these outlying masses is 

Boundary Cone, 3,429 feet high a sharp pinnacle rising 2,500 feet 

above the graded detrital slope which stretches from its base westward to Colorado River.

The rock of Black Mesa varies greatly in hardness, and erosion has 

carved out a great variety of topographic forms. In places where 

the mesa is composed of moderately uniform layers it is bordered by 

prominent cliffs of regular outline 1,000 feet or more in height. 

Where the rock varies in hardness within short distances, as at 

Union Pass, it is eroded into a great variety of castellated forms. 

(See PL VI, A.}

Rock masses. The granite forming the core of the Black Mountains extends southward underneath Black Mesa, but it is exposed in 

few places, the mesa to a depth of 2,000 to 3,000 feet being composed 

mainly of effusive rocks. Granite porphyry was found at the base 

of Boundary.Cone at the western edge of the mesa, and dark-colored 

andesite at the base of the cliffs at the northeastern extremity; the 

latter is best exposed in the vicinity of Gold Roads mining camp. 

The andesite rests upon the granite and is apparently overlain by 

rhyolite. Wherever observed, however, Black Mesa is composed 

mainly of rhyolitic tuff, breccia, and flow. The rhyolite is in turn 

cut by dikes of olivine diabase and overlain to some extent by sheets 

of basalt.

The granite underlying the rhyolite is penetrated by the well at 

Yucca and exposed at the base of the hills extending eastward into 

the Detrital-Sacramento Valley at the northern end of Black Mesa. 

The thickness of the effusive rock as determined at these points is 

about 3,000 feet.

MOHAVE MOUNTAINS.

Location. The Mohave Mountains are located south of Black 

Mesa, between the Colorado and the Sacramento valleys. They consist of a massive central group, with a spur, known as The Needles, 

extending westward to. Colorado River, and low unnamed hills 

extending southward to Williams River.

Topographic features. The central group is subcircular in outline 

and about 5,000 feet high. It is deeply scored by erosion, and is 

apparently the remnant of a once much more extensive mountain 

mass.

The Needles are irregular pinnacles resulting from the erosion of 

the mass of effusive rock which formerly extended across Colorado 

River and was later dissected by that river in cutting its present
28 RECONNAISSANCE OF PART OF WESTERN ARIZONA.

canyon. The unnamed hills north and south of the central mass are 

remnants of erosion, now separated from the main peak by debriscovered passes.

Rock masses. With the exception of The Needles, the rocks of the 

Mohave Mountains, so far as observed, are granite, gneiss, and later 

intrusives. The crystallines have been greatly fractured and faulted 

and contain many dikes and veins. The extrusive rock of The Needles overlies the crystalline complex on the eroded flanks of the 

Mohave Mountains, and is exposed in the canyon down to the river 

level. The thickness of the effusive rock as measured from the river 

bed to the summits of The Needles is about 2,000 feet.

HARCUVAR AND HARQUAHALA MOUNTAINS.

Location. The Harcuvar and Harquahala mountains are located 

in the southern part of the area described, and extend from the 

eastern border of this area about 50 miles in a general southwesterly 

direction. They resemble each other in many ways and may be 

described together.

Topographic features. The axes of these mountains lie in a direction practically at right angles to those of the other ranges of the 

region. Next to the Hualpai Mountains they are the loftiest in central western Arizona.

Both ranges are narrow, with precipitous slopes rising abruptly 

to altitudes of several thousand feet above the graded plain which 

surrounds them. The main range of the Harcuvar Mountains is 

broken at Cunningham Pass, and at either end the ranges break up 

into isolated hills. At the west end of. these mountains a group 

known as the Granite Wash Hills exhibits a tendency to return to 

the north-south trend characteristic of the other ranges of western 

Arizona.

Rock masses. The rocks were observed only in Cunningham Pass 

in the Harcuvar Mountains and near Harrisburg in the Harquahala 

Mountains, where they consist of a crystalline complex underlying 

and to some extent including masses of quartzite', argillite, and metamorphic limestone. A few miles south of Harrisburg, where these 

sediments were examined most closely, the strata stand nearly 

vertical.

BUCKSKIN MOUNTAINS.

Location. The Buckskin Mountains, lying immediately south of 

Williams River, are i virtually the southward continuation of the 

Aubrey Hills, being separated from them only by the narrow gorge 

cut by Williams River.

Topographic features. The Buckskin Mountains are lofty at their 

eastern extremity, with a precipitous slope facing southward. The
DETAILS OF VALLEYS. 29

group is greatly eroded, the peaks being separated by comparatively 

low passes. The western part is composed of irregular hills formed 

by the dissection of a plateau of igneous rock, the general surface of 

which has an altitude of about 2,400 feet. The topographic features 

of the basalt-covered plateau near the mouth of Williams River are 

especially conspicuous (PI. VI, B). The basalt of the surface is very 

resistant, and the underlying sand and gravel (see p. 54) is easily 

eroded, resulting in the formation of precipitous cliffs nearly 2,000 

feet high.

Rock masses. The rocks of the Buckskin Mountains consist of 

biotite granite, granitic gneiss and schist, metamorphic sediments, and 

effusive rocks. The gneisses and schists are conspicuously exposed 

in Williams Canyon, where they are horizontally laminated and 

fissile, suggesting the name Banded Canyon, by which Williams 

Canyon is locally known.

The crystalline rocks are overlain by quartzites, slates, and black 

metamorphic limestones. These are faulted and intersected by 

intrusive rocks, and contain deposits of copper and iron ore. A bed 

of hematite about 150 feet thick was observed near Planet.

PALOMAS AND DOME ROCK RANGES.

Location. The Palomas and Dome Rock Mountains, in the southwestern part of the region, were not visited by the writer. Their 

form and location are taken from the railway-location map made by 

the Santa Fe engineers in locating the Arizona and California Railroad, furnished for this bulletin by the chief engineer, W. A. Drake. 

Little is definitely known of their topographic features or rock masses.

GEOGRAPHIC AND GEOLOGIC DETAILS OF VALLEYS.

COLORADO VALLEY. 

. GENERAL STATEMENT.

Colorado River was traversed by bqat from the mouth of Grand 

Canyon southward to Yuma, a distance of about 325 miles. Throughout this course the rocks in which the valley is eroded are well exposed and geologic features of great variety are well exhibited. For 

convenience of description the valley is divided into sections, the 

important features being taken up in order from the mouth of the 

Grand Canyon downstream. Several diagrajnmatic sections across 

the valley are included with the descriptions in order to illustrate 

relations not adequately shown in the more generalized sections on 

PI. V.

In the published accounts of Major Powell's explorations of the 

Colorado little is said of the river west of the mouth of Grand Canyon.
30 RECONNAISSANCE OF PART OF WESTERN ARIZONA.

The current is swift as far south as the mouth of Black Canyon, the 

fall being about 400 feet, or about 5 feet to the mile. There are 

several rapids of considerable size, formed by bowlders washed into 

the river from tributary canyons. The largest of these are': (a) 

Near Pierce Ferry in the Grand Wash Trough, caused by bowlders 

from the Greggs breccia entering from the south; (b) at the mouth 

of Grand Wash, caused by bowlders from this wash; (c) 3 miles east 

of the Nevada-Arizona boundary, caused by bowlders from a small 

wash entering from the north; (d) Red Granite Rapids, 3 miles west 

of the Nevada-Arizona boundary, at which point there is a long 

bowlder strainer 0 on the Arizona side which deflects the river sharply 

against the red granite on the Nevada side; (e) Hualpai Rapids, 

formed by the bowlders from Hualpai Wash; (f) Reverse Rapids, in 

Boulder Canyon; (g) Roaring Rapids, in Black Canyon.

MOUTH OF GRAND CANYON.

Colorado River emerges from the Plateau region about 7 miles 

east of the Nevada-Arizona boundary. The Grand Wash Cliffs, which 

form the western border of the plateau, rise to an altitude of about 

4,500 feet, or 3,500 feet above the river. A few miles north of the rim 

of the canyon Shiwitz Plateau rises to an altitude of aboul, 6,300 feet.

Grand Canyon is very narrow at its mouth (PI. VII, B), and nearly 

perpendicular walls of Redwall limestone, sandstone and shale of the 

Tonto formation, and granite.(see pp. 14-15) rise from the water's 

edge on either side. Springs emerge from these formations in many 

places and deposit carbonate of lime. The lower portion of the canyon walls is covered in many places with calcareous tufa and pendants 

of travertine. In some places the travertine projects irregularly, 

inclosing picturesque cavefn-like chambers; in other places it forms 

basins built out into the river.

Massive beds of travertine were observed on both sides of the 

canyon at an elevation of 500 feet or more above the river. These 

may have been built out from the canyon sides by springs and later 

partly eroded away, but their horizontal bedding and location on 

opposite sides of the canyon at about the same altitude (see section 

A, fig. 3) indicate that they are probably remnants of a mass which 

formerly filled the canyon to a depth of several hundred feet. They 

are probably part of an extensive travertine formation having its 

greatest development near Hualpai Wash.

GRAND WASH TROUGH.

The Grand Wash Trough, lying between the Grand Wash Cliffs and 

Iceberg Canyon, is a depression formed by faulting and.by the tilting

a '''Strainer" is a term used locally to designate an accumulation of bowlders forming a porous dam 

in the river, through which the water finds its way as through a strainer.
U. S. GEOLOGICAL SURVEY BULLETIN NO. 352 PL. VII

A. NORTH WALL OF CANYON IN GRAND WASH TROUGH.

^^S£|<3S??

-a*- *%

JJ. MOUTH OF GRAND CANYON.
DETAILS OF VALLEYS. 31

of a large crust block. It derives its name from Grand Wash, which 

here enters the Colorado from the north. Its western limb consists of 

strata of the tilted block, and its eastern limb is the fault scarp of the 

Grand Wash Cliffs.

Not only are all the rock formations composing the Grand Wash 

Cliffs found in the tilted block in Iceberg Canyon, but strata younger 

than those in the cliffs are also present and pass beneath the river 

level with an eastward dip of 60° to 80°. Making no allowance for 

dip and considering only the altitude of corresponding strata in the 

walls of Grand Canyon and in Iceberg Canyon, the downthrow at the 

Grand Wash fault is 

about 5,000 feet. The 

strata of the block 

pass beneath- the river 

level several miles 

west of the fault line. 

If the downthrow be 

computed from the 

dip of the strata and 

the distance from the 

fault line at which 

they pass beneath the 

river, the displacement at Grand Wash 

fault appears to be 

several times greater 

than the 5,000 feet in 

evidence at the surface.

. The magnitude of 

the Grand Wash fault 

has long been recognized. Gilbert a states that the most profound 

dislocation of the plateau region has occurred at this fault, and Dutton,6 in describing it, writes that "the plateau had its origin in a 

great fault along the crest of which the country east of it has been 

hoisted several thousand feet above the country on the west." Again 

he writes "It [the Grand Wash Cliffs] is a feature of the highest 

importance, since it is the boundar}7 not only of the Grand Canyon 

district, but of the Plateau province itself. It drops the country on 

the west about 6,000 feet at a maximum." Huntington and Goldthwaite 0 have recently shown that the fault is traceable northward to

a Gilbert, G. K., Final Repts. U. S. Geog. Survey W. 100th Mer., 1873, pt. 1, p. 54.

6 Button, C. E., Tertiary history of the Grand Canyon district: Mon. U.S. Geol. Survey, vol. 2,1882, 

pp. 12,19.

c Huntington, Ellsworth, and Goldthwaite, J. W., The Hurricane fault in the Toquerville district, 

Utah: Bull. Mus. Comp. Zool. Harvard Coll., vol. 42,1904.

FIG. 3. Biagrommatic sections across Colorado River. A, At 

mouth of Grand Canyon; B, in Iceberg Canyon. 1, Cambrian; 

2, Redwall limestone; 3, travertine; 4, granite; 5, Greggs breccia.
32 BECONJSTAISSANCE OF PAET OF WESTERN AEIZONA.

the vicinity of .Toquerville, Utah, a distance of about 80 miles, where 

it joins the Hurricane fault. The present writer traced it southward 

into the Hualpai Valley, where it apparently forks, the western branch 

reappearing west of the Hualpai Mountains and the eastern one 

following the cliffs.

The Grand Wash Trough is filled with Greggs breccia to an altitude of about 2,500 feet, or 1,500 feet above the river. Where the 

breccia was examined most carefully, in the bluffs south of the river 

about 4 miles east of Greggs Ferry, it was found to be composed of 

unassorted and poorly stratified debris consisting of angular rock 

fragments, principally granite, the largest having a diameter of 10 

feet or more. Toward the top the fragments were cemented by 

carbonate of lime into a very resistant mass, forming the cap rock of 

certain conspicuous cliffs east of Greggs Ferry. The upper 100 feet 

or more of this capping stratum is travertine and is nearly devoid of 

rock fragments. Farther south the surface consists of the truncated 

edges of the upturned limestone block. (See section P-P', PL V.)

The breccia of the Grand Wash Trough has been much more eroded 

north of the river than south of it. The breccia was not examined 

far from the river, but, judging from the size and character of the 

bowlders brought down by the washes, it is probable that the material 

in the midst of the trough does not differ greatly from that described 

from the cliffs at its western edge near Greggs Ferry.

The Temple Bar conglomerate also occurs in the Grand Wash 

Trough, appearing in many places at altitudes several hundred feet 

higher than the river, in depressions previously eroded in the older 

rocks. It is composed of sand and waterworn pebbles of quartzite, 

limestone, marble, etc., not distinguishable at .the present time from 

the gravels derived from Grand Canyon. These are in places cemented by carbonate of lime into very resistant masses, forming 

nearly, perpendicular cliffs 500 feet high. The travertine deposits 

just described within the canyon were probably formed at the same 

time.

The Temple Bar conglomerate.of the Grand Wash Trough contains 

a thick sheet of basalt. The lava appears in the face of a cliff in 

Iceberg Canyon in the midst of the conglomerate, and in the Grand 

Wash Trough as a columnar sheet overlying the conglomerate. The 

relation of the Temple Bar conglomerate to the underlying sedimentary formations of the tilted block and to the overlying sheet 

of basalt is shown in PL VII, A.

The Greggs breccia, where exposed near the river within the 

Grand Wash Trough, is roughly stratified, and the strata are tilted 

eastward, the maximum dip observed being about 30°. The Temple 

Bar conglomerate is also locally disturbed, dips of 10° eastward being 

observed in places. At the base of the Grand Wash Cliffs the detrital
DETAILS OF VALLEYS. 33

material ends abruptly against the sedimentaries at the fault line, 

and is locally disturbed by movements apparently of recent date.

The somewhat complicated relations in the Grand Wash Trough 

may perhaps be made clearer by a brief statement of the events in 

the order of their occurrence. The formation of the Grand Wash 

fault and the tilting of the crust block were followed by a long period 

of erosion and deposition, which filled the trough with debris and 

planed off the upturned edge of the block, bringing the surface to* a 

graded condition. The Colorado Plateau to the east was apparently 

at the-level of this graded plain. Then followed a second period of 

faulting, in which great displacements occurred at the Grand Wash 

fault and minor displacements at several smaller faults to the west, 

accompanied by further tilting of the crust block and the elevation 

of the Colorado Plateau. This uplift of the plateau resulted in the 

inauguration of Grand Canyon, the river cutting directly across the 

Grand Wash Trough. The erosion proceeded until the canyon was 

cut to a depth practically the same as that it has at the present time. 

This was followed by deposition of gravels and of the Temple Bar 

conglomerate, and by eruptions of basalt, after which occurred renewed faulting and tilting of the limestone block, the Greggs breccia, 

and the Temple Bar conglomerate. Erosion again became active, 

and a second time the canyon was eroded to a depth greater than that 

it now has.

Later events, which are important farther downstream, are not 

conspicuously recorded in the Grand Wash Trough.

HUALPAI WASH.

Hualpai Wash enters Colorado River from the south and occupies 

a structural depression between the western edge of the limestone 

block on the east and the crystalline rocks of the White Hills on the 

west. This trough extends northward across the river and is there 

filled with gravel deposits, but their relation to other formations 

was not determined.

In Hualpai Wash a limestone several hundred feet thick occurs. 

In some places it is a massive, pink, compact rock resembling the 

Redwall limestone of the canyon section. Unlike that limestone, 

however, its character varies within short distances from a compact 

rock to a comparatively soft earthy substance, weathering with 

rough cavernous surface. In Hualpai Wash it rests directly upon 

an irregular surface of granite. In other places it abuts rather 

 abruptly against previously existing granite cliffs, and contains fragments of the granite embedded within it. In still other places it 

apparently rests upon beds of sand and clay, although this observation was not satisfactory.

49904 Bull. 352 08 3
34 RECONNAISSANCE OF PART OF WESTERN ARIZONA.

The material is similar in character to the travertine capping 

Greggs breccia (section C, fig. 4), and to that occurring in beds 500 

feet or more in thickness in the mouth of Grand Canyon (section A, 

fig. 3). It is apparently a travertine deposit belonging either to the 

Greggs deposits, let down to its present position by faulting (section 

D, fig. 4) or to the Temple Bar deposits, both of which are known to 

contain large beds of travertine. Its relation to the sedimentary

rocks and to the 

underlying granite 

of the tilted block 

to the east is shown 

in the sketch sections in fig. 4.

Within the canyon, resting unconformably upon Temple Bar conglomerate and the. older 

formations at various points on either 

side up to an altitude of 150 to 200 

feet above the water 

level, occur unconsolidated gravels. 

They are not conspicuous east of Iceberg Canyon, although some gravel 

beds in the Grand Wash Trough above high-water level may have 

been formed at the same time. Farther downstream they are conspicuously developed and are there known as the Chemehuevis gravel.

VIRGIN CANYON.

At the mouth of Hualpai Wash Colorado River enters a narrow 

rock gorge cut in the crystalline rocks of the Virgin Range. The 

canyon is about 5 miles long and from 1,000 to 1,500 feet deep, with 

walls rising steeply from the water's edge on either side.

High in the sides of the canyon walls occur remnants of lightcolored, horizontally bedded material. (See section E, fig. 4.) These 

were not examined closely, but from a distance they have the same 

general appearance as the Temple Bar conglomerate characteristically 

developed at the same altitude a few miles farther west.

FIG. 4. Diagrammatic sections across Colorado Kiver. C, 4 miles 

east of Greggs Ferry; D, near Hualpai Wash; E, in Virgin Canyon. 

1, Basalt; 2, Temple Bar conglomerate; 3, Greggs breccia; 4, Redwall 

limestone; 5, Cambrian; 6, granite; 7, travertine.
U. S. GEOLOGICAL SURVEY BULLETIN NO. 352 PL. VIII

A. TEMPLE BAR CONGLOMERATE RESTING UPON OLDER BRECCIA, NEAR TEMPLE BAR.

11. ENTRANCE TO BLACK CANYON.
DETAILS OF VALLEYS. 35

TEMPLE BAR.

Virgin Canyon widens westward as the river emerges from the 

crystalline rocks and enters the detrital beds. At Temple Bar the 

sand and gravel filling the Detrital Valley is exposed in vertical cliffs 

several hundred feet high. At the base of the cliffs is a coarse breccia 

exposed through a thickness of about 300 feet and composed principally of fragments of a rhyolite flow breccia cemented into a resistant 

mass. The cementing- material is mainly carbonate of lime, but in 

some places it is silica and in other places oxide of iron. Springs 

issuing from this 

breccia are strongly o »/

charged with common salt and alkali, 

which gather as 

white incrustations 

about the springs. 

Resting unconformably upon this 

breccia and abutting against it, as 

.illustrated in section F, fig. 5, occurs 

the characteristic 

Temple Bar conglomerate. The 

conglomerate consists of well-stratified sand and gravel 

(see PI. VIII, A), 

and, although 

poorly consolidated, 

forms perpendicular cliffs hundreds of feet in height. PL II shows this conglomerate 

in one of its most characteristic exposures, where the cliffs rise 

abruptly from the water's edge to a height of 815 feet. A large 

number of equally conspicuous sand and gravel cliffs and monuments 

occur in the vicinity of Temple Bar, extending from the river level to 

altitudes of 2,000 to 2,500 feet.

Sheets of basalt occur at several horizons of the conglomerate. A 

shelf about 200 feet from the base (see PI. II) is formed by one of 

these sheets of basalt, and other sheets occur at higher horizons 

(section F, fig. 5). South of the river a. basa.lt sheet resting on top 

of the gravel beds may be younger than those included in them, or 

may be one of the included sheets exposed by erosion.

FIG. 5. Diagrammatic sections across Colorado Eiver. F, At Temple 

Bar; G, at Virgin lliver; II, in Boulder Canyon. 1, Temple Bar 

conglomerate; 2, basalt; 3, Greggs breccia; 4, granite; 5, salt and 

gypsum beds.
36 RECONNAISSANCE OP PART OF WESTERN ARIZONA.

The composition, stratigraphic relations, and general appearance 

of the older or cemented breccia suggest that it is probably a time 

equivalent of the Greggs breccia. The gravels above it form the 

Temple Bar conglomerate, which derives its name from this locality. 

The younger or Chemehuevis gravel is also present at Temple Bar, 

but is not conspicuous.

VIRGIN VALLEY.

Between Temple Bar and Boulder Canyon, a distance of about 12 

miles, Colorado River crosses the old debris-filled valley which to the 

south of the Colorado is known as the Detrital-Sacramento Valley 

and to the north as the valley of the Virgin.

The filling of this old valley is apparently composed of two distinct 

formations, but their relation was not satisfactorily determined. 

The older one consists of alternating layers of sand and clay, and 

contains extensive beds of gypsum. Rock salt occurs in the Virgin 

Valley a few miles north of the Colorado, in beds similar to those 

containing the gypsum. These salt beds apparently lie beneath the 

gypsum, as shown by the salt well near the mouth of Virgin River, 

described by Gilbert.0 The salt well is a crater-like depression 

about 300 feet across and 65 feet deep, situated in the midst of a 

level gravel plain. It is not connected with any surface drainage, 

and is evidently formed by a local caving of the surface probably due 

to the removal by solution of underlying beds of salt. It is filled 

with salt water to a depth of 15 to 20 feet.

The gypsum and gypsiferous clays are conspicuously exposed 

along the river, where they are deeply dissected over a large area 

locally known as the badlands of the Virgin. The presence of gypsum and salt indicates that this formation is not a part of the Temple

Bar conglomerate, which overlies it with apparent unconformity 

(section G, fig. 5) and which does not contain gypsum or salt in its 

typical exposures so far as observed. The relation of the gypsiferous 

shales to the underlying rocks and to the overlying conglomerates 

was not satisfactorily determined. The stratigraphic position, however, suggests that this formation may be a time equivalent of the 

Greggs breccia.

BOULDER .CANYON.

Boulder Canyon is a sharp gorge cut by Colorado River through 

the Black Mountain Range. It is about 5 miles long and 2,000 feet 

or more in depth, the walls rising steeply from the water's edge. 

The rocks exposed in the canyon are syenite, gneiss, rhyolite, and 

basalt. The basalts and their associated gravel deposits near the 

entrance to the canyon are faulted and tilted to some extent, and 

faults and open fissures occur in the canyon walls.

a Gilbert, G. K., Final Kept. U. S. Geol. Survey VV. 100th Mer., vol. 3, 1875, pt. 1, pp. 109-110.
DETAILS OF VALLEYS. 37

Boulder Canyon is apparently younger than Virgin Canyon. The 

walls are but slightly eroded by lateral washes, although the open 

fissures and shattered condition of the rock in many places are 

favorable to the development of such; none were observed containing

beds of the Temple. Bar conglomerate, as is the case in Virgin Canyon.

)

LAS VEGAS WASH.

West of Boulder Canyon, and extending southward to the head 

of Black Canyon, the river flows through a debris-filled basin in 

which Colville and 

Las Vegas washes 

join the river from 

the north and west. 

Detrital beds resembling the Temple Bar conglomerate and containing 

sheets of lava are 

capped by a thick 

lava sheet in Fortification . Hill at an 

altitude of 3,500 

feet, or nearly 2,500 

feet above the river 

(section I, fig. 6). 

The gravels are well 

stratified and are 

faulted and tilted 

in places.

yi||)llllHUlllllUlllllllll)iyiM X~N I (\ /" s'£

 f u^^^^^^^^^lii'^^^

BLACK CANYON. FIG. 6. Diagrammatic sections across Colorado River. 7, Near Las 

Vegas Wash; J, in Black Canyon; K, at Little Round Island. 1, Basalt; 2, Chemehucvis gravel; 3, Temple Bar conglomerate; 4, granite; A 5, andesite and rhyolite. few miles south 

of Fortification Hill 

the river leaves the detrital basin and enters Black Canyon, a deep, 

narrow rock gorge about 18 miles long. The walls rise steeply from 

the water's edge (see PI. VIII, B], and are composed to some extent 

of coarse crystalline rock, but mainly of massive rhyolite (section J, 

fig. 6). Black Canyon is very similar to Boulder Canyon in its 

general youthful appearance and in the absence of notable tributary washes and remnants of gravel beds.

COTTON WOOD VALLEY.

A few miles north of Eldorado Ferry the river emerges abruptly 

from. Black Canyon into a broad open basin, the central part of
38 RECONNAISSANCE OP PART OF WESTERN ARIZONA.

which is known as the Cottonwood Valley. The basin is about 30 

miles long and extends laterally from the Dead Mountains on the 

west to the Black Mountain Range on the east. At the northern

.'.'.- . ' ' Chemehuevis gravel

FIG. 7. Map of a part of the Colorado Valley at the northern end of the Cottonwood Valley, showing an old gravel-filled channel at the right and the rock channel of the river at the left.

end of the basin gypsum-bearing beds similar to those near the 

mouth of the Virgin, occur with an observed thickness of several 

hundred feet.
U. 8. GEOLOGICAL SURVEY BULLETIN NO. 352 PL. IX

Topography from 

U. S. Reclamation Service maps

200 o ?oo 400 600 800 looo feet

I I I , 1 , I , I . I , I I I 

Contour interval 10 feet

MAP AND SECTION AT SOUTH END OF PYRAMID CANYON, COLORADO RIVER.
Ml DETAILS OF VALLEYS. 39

"S Near Round Island partly consolidated gravel beds similar in 

general appearance to the Temple Bar conglomerate and intersected 

by basalt dikes (see section K, fig. 6) occur above andesitic lavas. 

The gravels are well stratified, tilted steeply to the east, and extenA sively eroded. Horizontally bedded Chemehuevis gravel lies in 

depressions eroded in older upturned beds which in turn are younger

,t| than the andesites. For these reasons the older gravels are pro-

^ visionally correlated with the Temple Bar conglomerate.

The Cottonwood Valley .is the northernmost of a series of large

 .basins which extend thence southward to the Gulf of California.

^ The flood plain in the center of the valley is terminated laterally

by bluffs of the Chemehuevis 'gravel. Between these bluffs and the

* mountains on either side are long corrugated slopes covered with 

angular rock d6bris or wash from the highlands. The slopes in the 

Mohave Valley were examined with more care than elsewhere, and 

are described in a following section. (See pp. 41-42.)

At Eagle Rock, near the southern end of Round Island, the river 

leaves the flood plain and flows through a narrow rock gorge about a 

mile long and 150 feet deep. The rock is andesite, and its relation 

to the gravel formations is shown in fig. 7. The gravel-filled channel 

to the east connects the Round Island Valley with the Cottonwood 

Valley proper. In other words, Colorado River, during one of its 

periods of canyon cutting, described under "Geologic history" 

(pp. 62-67), failed to reexcavate its old gravel-filled channel at Eagle 

Rock and cut a new channel in the rock west of the old one.

PYRAMID CANYON.

South of the Cottonwood Valley the granite and gneiss of the 

bordering mountains extend across the valley of the Colorado, and 

through these rocks the river has cut a canyon about 300 feet deep 

and 8 miles long. This is known as Pyramid Canyon, the name 

being derived from a pyramid-shaped rock near the northern end. 

East of the canyon, and separated from it by a narrow rock ridge 

(see PI. IX), is an old channel filled with sand and gravel Chemehuevis gravel remnants of which occur 400 feet or more above the 

river, overlying and abutting against the granite and gneiss, as shown 

in PI. Ill, B.

One of the proposed dam sites' of the Reclamation Service is 

located at the southern end of Pyramid Canyon, near Bulls Head 

rock, the southern extremity of the rock ridge. On account of the 

investigations of the Reclamation Service in this vicinity much 

exact information is available. On this account the Bulls Head 

region is perhaps the best locality for the description and illustration 

of the late physiographic history of Colorado River. Unfortunately
40 RECONNAISSANCE OF PART OF WESTERN ARIZONA.

the detailed maps do not extend far enough northward to show to 

advantage the relation of the new rock channel to the old gravel-filled 

valley, but its southern end is shown in PL IX, and its relations 

are indicated in fig. 8. In PL X, A, a view of Bulls Head rock is 

presented, showing the river channel to the left and the gravel-filled 

valley to the right, as seen from the south. At intervals for several 

miles north of Bulls Head rock the ridge between the old and new 

channel is cut through by tributary washes, exposing such sections 

of the Chemehuevis gravel as that shown in PL III, B.

The old course was not so satisfactorily traced to the south. 

As shown on the map, it apparently crossed the present course of the 

river at a point where the gravels fill a depression similar to that at

~^'/-r'ii'Wi~'f'>'*~ Granite gneis

FIG. 8. Profiles across Colorado River at trie southern end of Pyramid Canyon, constructed from 

boring records. (For location see PI. IX.)

the north, and connected with the extensive gravel deposits of the 

Mohave Valley to the south.

Although the river occupies a narrow rock channel in Pyramid 

Canyon, it does not flow upon a rock bed, as might be expected. 

Borings were made for the Reclamation Service in three localities 

across the river (see PL IX), and the gravel filling was found to be 

more than 100 feet deep. The probable profiles, as constructed 

from the boring records, are shown in fig. 8.

No distinction can be drawn with certainty between the old and 

new channels at the places where the borings were made. At the 

northernmost locality (section A-B, fig. 8) the channel at the left now 

occupied by the river, in which the gravels are about 50 feet deep, 

is apparently the new one, and that at the right, more than 100 feet
U. S. GEOLOGICAL SURVEY BULLETIN NO. 352 PL. X

A. COLORADO RIVER AND GRAVEL-FILLED VALLEY AT BUl_S HEAD RuCIV

IS. TILTED GRAVELS IN SACRAMENTO WASH.
DETAILS OF VALLEYS. 41

deep, the old one; but in the absence of soundings within the canyon 

north of Bulls Head, the depth of the new channel remains in doubt. 

Borings 100 feet deep in the older channel do not penetrate through 

the gravels.

A brief statement of the physiographic history of the river, as 

here recorded, may give a clearer understanding of the phenomena 

described. The river at some former time occupied the old course 

to the east (PL IX) and eroded its channel to a depth considerably 

below the present river level. Later the Colorado deposited the 

Chemehuevis gravel, filling its valley with sand and gravel to a 

level several hundred feet above the present bed. When the river 

again began to "erode, it reexcavated the old valley throughout the 

greater part of its course, but in Pyramid Canyon, at Eagle Rock 

(described in the previous section), and at other places farther south 

to be described in following sections, it left its old course and cut 

rock gorges at one side.

MOHAVE VALLEY.

The Mohave Valley is a large basin extending from Bulls Head 

southward to The Needles, a distance of about 35 miles. The center 

of the basin is occupied by a broad flood plain having an area of 

about 50,000 acres. This is bordered on either side by terraced 

gravel bluffs, from which long, graded, alluvial slopes extend to the 

bordering mountains, joining the slopes at altitudes of 2,500 to 3,000 

feet.

The rock masses in the Mohave Valley were examined principally 

east of the river. The rocks of Black Mesa to the east are mainly 

andesite and rhyolite, resting upon granitic gneiss. . Overlying these 

older rocks occurs a formation of partly consolidated sand and gravel, 

which in composition and general appearance resembles the Temple 

Bar conglomerate. It is exposed -in steep cliffs in the washes of the 

alluvial slope, and the strata are generally nearly horizontal. In 

some places, however, the layers are faulted and tilted (see PI. X, B}. 

These stratified sands and gravels are covered with coarse rock debris, 

due partly to wash from the hills and partly to surface concentration of the coarser material of the conglomerate.

Resting upon this formation and occupying spaces eroded in it is 

the Chemehuevis gravel, forming conspicuous terraces, three of 

which are prominent and traceable continuous^ for considerable 

distances; in some places five are distinguishable. The lowest is 

about 50 feet above the river, and is represented by the broad shelf 

upon which old Fort Mohave stands; the second is about 100 feet 

higher, and the others occur at intervals of 50 to 100 feet.

The Chemehuevis gravel varies considerably in character from 

place to place from beds of large, well-rounded pebbles to those of
42 RECONNAISSANCE OF PAET OF WESTERN sARIZONA.

M

fine sand and clay. At the northern end of the Mohave Valley, near 

Bulls Head, there are two distinct divisions of the gravel. (See PI. 

Ill, B.} The lower division consists mainly of well-stratified and 

firmly packed sand and silt; the upper of stratified but very loose 

sand and gravel. The two divisions appear to be perfectly conformable, and the difference in character is probably due to some change

in the river, such as 

an increase in its 

carrying power, enabling it to bear the 

finer material away 

and deposit only 

the coarser material ; or to- a change 

in course, bringing 

the gravel-bearing 

current over what 

had formerly been 

a flood plain.

The gravels in the 

old channel east of 

Pyramid Canyon 

were examined with 

considerable care 

and found to consist 

of limestone, marble, sandstone, and 

metamorphic and 

igneous rocks of 

great variety. Many

of the limestone 

pebbles have beautifully etched surfaces, which Gilbert a describes as "carved with a network of vermicular grooves into a most beautiful arabesque design." These 

etched pebbles were observed in the Chemehuevis gravel throughout

FIG. 9. Diagrammatic sections across Colorado River. L, Pyramid 

Canyon; M, in the Mohave Valley; N, in the Needles Mountains; 

0, at the mouth of Williams River. 1, Chemehuevis gravel; 2, granite; 3, Temple Bar conglomerate; 4, eruptive; 5, basalt.

the region described.

THE NEEDLES.

South of the Mohave Valley occurs a mass of eruptive rock resting 

on the .flanks of the Mohave Mountains (section N, fig. 9), and characterized by sharp pinnacles of erosion, from which the group has been 

called The Needles. Mohave Canyon, about 8 miles long, has been 

cut in this eruptive mass to a depth of about 2,000 feet. In gen-

« Gilbert, G. K., U. S. Geog. Surv. W.- 100th Mer., vol. 3, 1875, pt. 1, pi. 9 and p. 83.
DETAILS OF VALLEYS. 43

eral the rock walls rise abruptly from the water's edge, but in some 

of the more open spaces sand and gravel of the Chemehuevis formation occur to a considerable height above the river.

At Big Bend, 4 miles south of Mellen, the river leaves a comparatively open portion of the canyon and turns abruptly to the west 

into a narrow rock gorge having an old gravel-filled channel, which 

continues southward in the normal direction of the river (fig. 10).

Topography from Needles 

special map

Scale _, 

0 /4 Vz A- i mile

FIG. 10. Map of Great ]3end in Mohave Canyon, showing relation of an old dcliris-filled channel to 

the present course of Colorado River.

The phenomena here are similar to those just described from Pyramid 

Canyon, except that the new course is shorter and the gravel filling 

of the old one has been more nearly eroded away than in Pyramid 

Canyon.

CHEMEHUEVIS VALLEY.

The Chemehuevis Valley extends from The Needles to the mouth 

of Williams River, a distance of about 25 miles, and is narrower than
44 RECONNAISSANCE OF PART ?)F WESTERN ARIZONA.

the other basins along the course of the river. The Chemehuevis 

gravel, which derives its name from this valley, occurs here in characteristic development, lying unconformably upon older and partly 

consolidated gravels. The older gravels are horizontally bedded 

in some places but in others are faulted and highly inclined.

The relation of the Chemehuevis gravel to the older conglomerate 

was noted at several points along the river. In some places the older 

gravels are undisturbed beneath the Chemehuevis, the two being 

separated by an unconformity of erosion (section A,fig. 11). In other 

places the older gravels are upturned, eroded, and overlain by horizontally stratified Chemehuevis gravel (section B, fig. 11). In still

FIG. 11. Relations of gravel formations to each other and to igneous rock in the Chemehuevis Valley. 

A, The three gravel formations horizontally bedded but separated by unconformities of erosion; B, 

the older conglomerate tilted, eroded, and overlain by horizontally bedded younger gravels; C, the 

older gravels tilted, intersected and overlain by lava, eroded, and again overlain by horizontally 

bedded younger gravels. 1, Flood-plain deposits; 2, Chemehuevis gravel; 3, Temple Bar (?) conglomerate; 4, igneous rocks.

other places the older gravels are tilted, intersected by lava, eroded, 

and overlain by the Chemehuevis gravel (section 0, fig. 11).

The older gravels apparently overlie rhyolite and andesite, and at 

one point a stratum of rhyolitic ash occurs within them. They vary 

greatly in character from place to place from sandy clay to a breccia 

with granite bowlcfers 4 feet in diameter. In general appearance 

they resemble the Temple Bar conglomerate, and are provisionally 

correlated with it. This conglomerate is apparently the one which 

Newberry a in the Ives report referred to the Tertiary.

AUBREY CANYON.

Near the southern end of the Chemehuevis Valley the granite 

of the bordering mountains approaches the river, and at the mouth 

of Williams River the Colorado enters a narrow canyon, the walls of

<* Newberry, J. S., Report upon the Colorado River of the West by Lieut. J. C. Ives, pt. 3,1861, p-. 29.
DETAILS OF VALLEYS. 45

which are composed of granite overlain by eruptive rock (section 0, 

fig. 9). The eruptives west of the canyon were not examined closely, 

but resemble in general appearance the rhyolite and andesite to the 

north and the great masses of similar rock composing the Chocolate 

Mountains to the south. The eruptive rock east of the river is the 

basalt which caps the Temple Bar conglomerate, as described and 

illustrated from Williams Canyon (fig. 16).

East of Aubrey Canyon, and exposed in the bluffs of Williams 

Canyon (see p. 54), is an old valley filled to a depth of about 1,000 

feet with the,Temple Bar conglomerate and covered with 800 feet 

of basalt. Aubrey Canyon is younger than this gravel-filled valley, 

having been cut through the basalt sheet covering the Temple Bar 

conglomerate.

The rock channel in Aubrey Canyon has been cut to a considerable 

depth beneath the present river level, and filled with sand and 

gravel. Borings made for the Reclamation Service near the head of 

the canyon failed to reach bed rock at a depth of 75 feet. In the open 

basins the river is building flood plains, and the sediment accumulated within the canyon evidently corresponds with that in the open 

basins, but the maximum depth of this most recent deposit is nowhere indicated.

Here, as elsewhere along Colorado River, there is abundant evidence of a complex physiographic history. A broad valley, described 

elsewhere as the Detrital-Sacramento Valley (see p. 52), was formed 

east of Aubrey Canyon and filled to a depth of 1,000 feet or more with 

sand and gravel the Temple Bar conglomerate. This was covered 

with 800 feet or more of basalt, and a new canyon was later eroded 

west of the old one. (section 0, fig. 9). Still later this canyon was 

filled with several hundred feet of sand and gravel Chemehuevis 

gravel which were partly carried away by renewed erosion that 

cut the canyon to a depth lower than the present river level. This 

channel was in turn filled to its present .condition.

GREAT COLORADO VALLEY.

The Great Colorado Valley was examined only in the immediate 

vicinity of the river during a somewhat hurried excursion by boat, 

but the data obtained are supplemented to some extent by the 

investigations of the Reclamation Service. The valley is the largest 

of the basins through which Colorado River flows, extending, with 

varying width, from Aubrey Canyon southward to the Chocolate Mountains, a distance of about 75 miles. The Riverside and 

Halfway mountains form a partial boundary on the west, and the 

Dome Rock and other mountains on the east; but between the mountain groups occur broad grades, such as the Cactus Plain.
46 RECONNAISSANCE OF PART OF WESTERN ARIZONA.

TOPOGRAPHY TAKEN FROM 

U. S. RECLAMATION SERVICE MAPS

FIG. 12. Map and sections of a part of the Great Colorado Valley, illustrating the lateral migrations 

of the river, the relation of the flood plain to the bluffs of the Chemehuevis gravel, and the corrugated 

slopes at the margins of the valley.
DETAILS OF VALLEYS. ' 47

Like the other basins described, the Great Colorado Valley contains 

gravels representing three distinct epochs of accumulation. The 

oldest, interpreted as belonging to the Temple Bar conglomerate, 

was observed near the northern end of the valley, where it is overlain 

by lava, as at Headgate Rock. Farther to the south, in the middle 

of the valley, it was not identified.

The younger or Chemehuevis gravel occurs throughout the Great 

Colorado Valley in conspicuous terraced bluffs. The beds vary much 

in composition, from a sandy silt to coarse gravel, the finer material 

greatly predominating. The sand is regularly stratified, cross-bedded, 

and not distinguishable in physical character or composition from 

the beds forming at the present time over the flood plain. The 

Chemehuevis gravel extends for an undetermined distance back from 

the terraced bluffs, and form corrugated slopes illustrated in fig. 1.2. 

The washes entering at the sides of the valley have steeply graded

floors, often extending back many miles toward the hills, and are terminated laterally by nearly perpendicular walls. These floors often 

join laterally, forming wide graded slopes.

From the foot of the gravel bluffs (fig. 12) and extending throughout the valley with a maximum width of 12 miles and a length of 75 

miles are flood plains building up by the deposition of sand and silt. 

Over this great area Colorado River is continually shifting its channel, sometimes gradually by slow cutting and filling and sometimes 

suddenly by turning through one of the numerous abandoned 

channels.

The annual floods carry immense quantities of silt, which they 

spread over the flood plain, building it up with great rapidity. Where 

the caving banks of the river expose vertical sections it was noted 

that the roots of living arrow weeds had been buried to a depth of 6 

feet or more. In other words, there have been accumulations of silt 

6 feet or more in depth during the life of this shrub. The material 

is well- stratified, sometimes with horizontal lamination, but often 

showing a conspicuous oblique lamination similar to that found in 

the Chemehuevis gravel. Much of the silt is very fine and is held in 

suspension for a long time. When deposited in thick beds it dries 

and cracks in columnar form, some of the columns being 2 to 3 feet 

in diameter and separated by cracks several inches wide and 2 feet or 

more deep.

CHOCOLATE MOUNTAINS.

South of the Great Colorado Valley, for a distance of about 30 

miles, Colorado River flows in a canyon or narrow valley through the 

Chocolate Mountains a name applied generally to a complex group 

consisting of the Spire Range, the Picacho group, the Castle Dome 

Mountains, and the Purple Hills.
RECONNAISSANCE OF PART OF WESTERN ARIZONA.

Topography from U.S.Reclamation Service maps

FIG. 13. Map and section of a part of Chocolate Canyon, showing an old debris-filled channel to the 

east of the present channel. (Section constructed from boring records.)
DETAILS OF VALLEYS. 49

The rock exposed along the river is principally effusive, although 

granite and metamorphosed sediments occur in some places. The 

effusive rock, consisting of pink and white rhyolite in the form of ash, 

breccia, and flow, extends from the river level apparently to .altitudes of several thousand feet, and is characterized by conspicuous 

cliffs, erratic forms of erosion, and rock slopes barren of vegetation.

Physiographic changes similar to those at Bulls Head and elsewhere were noted in Chocolate Canyon. At Lighthouse Rock the 

river has apparently left its old channel and cut laterally into the 

rhyolite, leaving Lighthouse Rock standing in the water. A.boring 

in the channel at this point failed to reach bed rock at a depth of 80 

feet. Farther down the river, near Picacho, several borings in the 

river bed failed to reach solid rock at a depth of 100 feet.

Probably the best illustration of changes in the course of the river 

in this vicinity is to be found at the so-called Cacopah dam site of the 

Reclamation Service, near the southern end of Chocolate Canyon. 

At this point the Colorado flows close to the rhyolite hills on the west, 

with one rock island standing in the river and another on the eastern 

bank. (See fig. 13.) Between these islands and the hills to the east 

is a broad sand flat.

Borings made at the various places indicated in fig. 13 show that 

the channel now occupied by the river has been eroded, to a depth of 

about 100 feet, and later filled with sediment, while the. old channel 

to the east is deeper, no solid rock being found at a depth of 138 feet.

A significant observation was made at this point by Homer Hamlin,a who noted that in one of the borings the drill penetrated through 

the rhyolite and entered a gravel bed. (See fig. 13.) The rhyolite is 

presumably of Tertiary origin, as are also the rhyolites farther north, 

more fully described elsewhere (p. 83). It is possible that the underlying gravels may be equivalent in age to some of the tilted and consolidated gravels farther north, which were referred by Newberry 

to the Tertiary, but which the present writer has provisionally 

correlated with the Temple Bar conglomerate and referred to the 

Quaternary.

HUALPAI VALLEY.

Location and character. The Hualpai Valley, about 60 miles long 

and 25 miles wide, is located in the northeastern part of the region 

described. Except for a few miles at the northern end, it is an 

undrained basin, in the lowest part of which flood waters gather and 

remain until they either evaporate Or sink into the valley filling. 

"RedLake," thus formed, contains water for periods varying from 

a few days to several months. At other times it is a broad, barren 

mud flat.

a Personal cominunicatipn, 

49964 Bull. 352 08 4
50 RECONNAISSANCE OF PART OF WESTERN ARIZONA.

The floor of the Hualpai Valley is nearly level at an altitude of 

about 3,000 feet and is met on either side by mountain slopes at high 

angles. The plateau to the east drains away from Hualpai Valley 

into Colorado River, and the drainage from the White Hills and the 

Cerbat Mountains to the west and from the Hualpai and Peacock 

mountains to the south is so small as to be negligible. The only 

stream worthy of note that enters this great valley is Truxton Creek, 

the bed of which is usually dry, but which occasionally contains floods 

of great volume.

Structure. The Hualpai Valley is a structural trough formed by 

faulting and block tilting. The Grand Wash fault, with a displacement of 10,000 feet or more at the mouth of Grand Canyon, continues 

southward into the valley, together with several smaller faults to the 

west. The general trend of this fault zone in the vicinity of Colorado 

River, where it is best known, suggests that it may extend through 

the Hualpai Valley beneath the detrital accumulations and reappear 

in the fault west of the Hualpai Mountains. On the other hand, 

extensive displacements by faulting have taken place along the Cottonwood and Aquarius cliffs (see pp. 19-20), and it is possible that 

these cliffs mark the southward extension of the Grand Wash fault.

At the northern end of the valley the sedimentary formations are 

tilted steeply to the east; along the eastern flank of the White Hills 

and Cerbat Mountains the sheets of basalt dip eastward beneath the 

valley floor. The trough formed by this downthrow to the east has 

been filled with rock debris to some unknown depth; a well bored 

700 feet deep near the head of Hualpai Wash did not pass through 

it. The material on the alluvial slopes is coarse, but in the center of 

the valley it is fine and is continually shifted by the winds.

BIG SANDY VALLEY.

Location and character. The Big Sandy Valley is located between 

the Aquarius Cliffs on the east and the Hualpai Mountains and 

Aubrey Hills on the west, and extends from Hackberry southward 

to Williams River. The lowest part of the valley, known as Big 

Sandy Wash, lies at the foot of the cliffs as far south as Signal, but 

at this point the Big Sandy leaves the main valley and passes through 

Signal Canyon. Several streams of considerable size emerge from 

the plateau to the east through deep, narrow canyons and discharge 

into the Big Sandy. The largest of these are White Cliff, Trout, and 

Sycamore creeks.

That portion of the valley between the Hualpai Mountains and 

Big Sandy Wash, consists of a long, graded detrital slope (see fig. 2, 

p. 24), more or less deeply cut by parallel washes, such as Deluge 

Wash. This highly inclined detrital slope, the western fault scarp 

of the Hualpai Mountains, and the fault scarp to the east (Aquarius 

Cliffs) all terminate at the south in practically the same latitude. 

The southern end of the valley, between the Artillery Mountains and
DP:TAILS OF VALLEYS. 51

the Aubrey Hills, has a slight inclination to the east, but is in general 

an undissected and undrained detrital plain.

Rock formations. The oldest rocks in the Big Sandy Valley are 

the granites exposed in the bordering mountains and cliffs, which, 

because of their resemblance to the granite beneath the Cambrian 

sediments in the Grand Wash Cliffs, are thought to be of pre-Cambrian 

age. They are overlain in places by Tertiary andesites.

The trough formed by these older rocks is partly filled with rock 

debris which has been later exposed by erosion. The oldest detrital 

beds have been upturned and eroded to'depths of 800 feet or more. 

They are composed of clay, sand, and gravel, and in places contain

FIG. 14. Sketch section across Big Sandy Wash near mouth of Deluge Wash, showing the older gravels 

tilted eastward, eroded, and overlain by younger gravels, and again eroded and partly covered by 

recent flood-plain deposits. 1, Flood-plain deposits; 2, Temple Bar (?) conglomerate; 3, gravel.

granite bowlders 5 to 8 feet in diameter. In other places, as at 

Deluge Wash (PI. IV, B], they are composed of clay and fine, wellstratified sand and volcanic ash.

Within the valley eroded in the oldest tilted detrital beds, and 

resting with horizontal bedding upon their eroded edges, is a second 

series of gravel deposits. These are perhaps best exposed near the 

mouth of Deluge Wash, where they are about 50 feet thick. This 

second gravel accumulation was in turn eroded and a third deposit 

laid down. (See fig. 14.)

In general character and stratigraphic position the oldest detritus 

corresponds with the Temple Bar conglomerate, the middle with the

FIG. 15. Sketch section across Big Sandy Wash at the mouth of Trout Creek, showing the older 

gravels overlying granite, tilted eastward, and terminating against the granite of Cottonwood 

Creek. 1, Flood-plain deposits; 2, Temple Bar (?) conglomerate; 4, granite.

Chemehuevis gravel, and the youngest with the flood-plain deposits 

of the Colorado Valley, but no definite correlation can be made at 

the present time.

Structure. The Big Sandy Valley is a trough formed by faulting. 

The fault zone along the Grand Wash and Cottonwood cliffs continues 

southward to the Aquarius Mountains. Recent movement along this 

zone is indicated by the displacement of-portions of the andesite sheet 

at the northern end of the valley and by the faulted and tilted gravel 

beds near the mouth of Trout Creek (fig. 15), where the strata incline
52 RECONNAISSANCE OF PART OF WESTERN ARIZONA.

32° to the east and end abrubtly against the granite at the fault line. 

This evidence of faulting, considered in connection with the faulting 

and block tilting in the Hualpai Mountains, indicates that the Big 

Sandy Valley was formed by a downthrow of the eastern edge of the 

Hualpai block. (See fig. 2 and section S-S', PL V, p. 24.)

SIGNAL CANYON.

At the town of Signal the,Big Sandy leaves the debris-filled trough 

and passes through a rock gorge known as Signal Canyon. The rocks 

exposed are coarse-grained granites in the northern part of the canyon 

and andesites in the southern part. These rocks had been deeply 

dissected previous to the accumulation of the older detrital beds 

(just described) which later filled the old valleys and were in turn 

buried beneath effusive rock. Later, during the erosion of Signal 

Canyon, these old valleys were reexcavated in part, leaving on the 

mountain sides conspicuous shelves of lava-covered detritus. (See 

PL III, A.)

The broad, debris-filled trough here called the Big Sandy Valley 

continues southward west of the Artillery Mountains to Williams 

Canyon, where the detritus is seen to extend lower than the bed of 

Williams River.

DETR1TAL.-SACRAMENTO VALLEY.

Location and character. The Detrital-Sacramento Valley extends 

from Colorado River on the north to Williams River on the south, 

between the Cerbat and Hualpai mountains to the east and the Black 

Mountain Range to the west. Thus defined it is about 130 miles long 

and 5 to 15 miles wide. The northern part of the valley, drained by 

Detrital Wash, is locally known as the Detrital Valley, and the central part as the Sacramento Valley. (See PL XL) The southern 

part bears no name, but since it is the southern continuation of the 

Sacramento Valley, the whole is here called the Detrital-Sacramento 

Valley.

The valley was apparently formed mainly by erosion, although its 

form has been modified by crustal movements; such is notably the 

case west of Chloride, where sheets of basalt, outpoured within the 

valley, have been tilted eastward. The andesites and rhyolites on 

either side, from the southern end of Black Mesa northward to Colorado River, are similar in character and occur at about the same level. 

They are probably remnants of a single effusive mass through which 

the Detrital-Sacramento Valley was eroded.

The depth to which this valley was cut is not definitely known. 

At the northern end it was deeper than the present Colorado Valley 

(altitude 800 feet), and in Williams Canyon (altitude 505 feet) it 

extends beneath the bed of the river. The maximum depth between
U. S. GEOLOGICAL SURVEY 

SACRAMENTO VALLEY AT SOUTH END OF HUAL
DETAILS OP VALLEYS. 53

these extremities is not known. At Yucca (altitude 1,804 feet) the 

bottom of the gravels was reached in a well at a depth of 905 feet, 

or at an altitude of about 900 feet above sea level. The general altitude of Black Mesa, a few miles west of Yucca, and of the mesa east 

of the valley near Kingman, is about 3,500 feet. Assuming that the 

mesas are remnants of the surface which formerly extended across 

the Detrital-Sacramento Valley, the known depth of erosion at Yucca 

is about 2,500 feet. Since the valley is known to be deeper than this 

at both the northern and southern ends, it is probable that the well 

at Yucca does not penetrate the filling at the deepest point and that 

the depth of the old valley is greater than 2,500 feet.

Detrital filling- The Temple Bar conglomerate filling this ancient 

valley is exposed at the north in the banks of Colorado River (PI. II) 

and at the south in Williams Canyon (PI. VI, B}. It is composed of 

horizontally bedded sand, gravel, and wash, and contains sheets of

basalt at several horizons. The composition of the filling at the 

extremities of the valley is described under "Temple Bar" (p. 35), 

and under "Williams Valley" (p. 54), and need not be repeated here. 

Where exposed in the washes throughout the valley and penetrated 

by wells the material does not differ greatly in character. Horizontally bedded sand and gravel containing sheets of basalt and 

having the same general appearance as the beds at Temple Bar and 

in Williams Canyon were observed within the valley up to altitudes of 

2,500 feet or more, and sheets of basalt within the detrital beds 

were penetrated in the well at Drake. For these reasons the detrital 

filling is correlated with the Temple Bar conglomerate.

Considerable erosion has taken place within the Detrital-Sacramento Valley since the filling was completed. Sacramento Wash is 

1,000. feet or more lower than the valley floor farther north. This 

difference in elevation is probably due in part to surface warping, but 

is regarded as due mainly to erosion.

In general the sands and gravels of the Detrital-Sacramento Valley 

are covered with angular rock debris, consisting in part of fragments 

of basalt, andesite, rhyolite, and granite, working their way over the 

surface as wash from the hills, and in part of the coarser material 

originally deposited with the sand and gravel and accumulated 

by surface concentration during the later degradation as the finer 

material was washed away by the rains or blown away by the winds.

WILLIAMS VALLEY.

Location and character. Williams River, formerly known as Bill 

Williams Fork, is formed by the junction of two streams (Big Sandy 

Wash and Rio Santa Maria) and extends from this junction westward 

to Colorado River. The south fork, or Rio Santa Maria, emerges 

through a narrow canyon from the plateau to the east upon a broad
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Section exposediin the south wall of Williams Canyon, showing the relat

1, Basalt; 2, crystalline rocks; 3, flood-plain deposits; 4, Temple Bar c

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Can

esast of C

R
DETAILS OF VALLEYS. 55

sheet and contains fragments of scoriaceous basalt immediately above 

each, sheet. The basalt extends completely across the old debrisfilled valley to the rock walls on either side.

That the basalt burst upward through the sands and gravels in the 

midst of the old filled valley is proved by the occurrence of a large dike 

or neck, about 400 feet wide and several thousand feet long, exposed 

in the Williams Valley near the point where the section was made. 

The stratified deposits through which this dike broke are disturbed and 

burned to a brick red for about 300 feet from the dike. Several 

smaller dikes occur in the vicinity, and some of the eruptive masses to 

the north, seen only from a distance, appear to be volcanic necks 

standing as sharp pinnacles several hundred feet above the level of the 

surrounding plain.

OTHER VALLEYS.

Location and character. There are several intermontane plains 

south of Williams River, known as the Cactus, Posas, and Ranegras 

plains, McMullan Valley, and an extensive unnamed plain south of the 

Harquahala Mountains. These are parts of the great desert plains of 

southwestern Arizona. They are, in part at least, old debris-filled valleys similar to those just described, but their original depth and the 

character of the filling can be judged only by surface indications. 

These plains have a general altitude of about 2,000 feet in the eastern 

half of the area described, and decline gradually westward to Colorado 

River (altitude 345 feet).

Detrital filling. Near Williams River the Cactus Plains have been 

somewhat dissected by erosion; detrital bluffs 500 feet or more in 

height occur, while the total depth of erosion into the detritus (the 

difference between the general surface altitude of 2,000 feet and the 

river elevation of 600 feet) is about 1,400 feet. The bluffs thus exposed are composed of clay, sand, gravel, and angular rock fragments, 

consisting of granites, andesites, etc., with sheets of embedded basalt. 

Near the mouth of Date Creek a sheet of basalt about 30 feet thick 

caps the bluffs, but passes into the detrital beds a short distance back 

from the face of the cliffs. West of Date Creek two basalt sheets occur 

in the detrital beds. The lava was outpoured upon an old surface and 

metamorphosed the material beneath it to some extent. At the surface of each of the lava sheets the cavities contain zeolites, and the 

overlying sands contain fragments of the basalt, indicating that the 

gravels and the lavas are contemporaneous.

The detrital material exposed in the bluffs is comparable in thickness and has the same general appearance as the oldest detritus in the 

Big Sandy Valley and the Temple Bar conglomerate of the DetritalSacramento Valley. . The b.asalt sheets embedded in it have the same
56 RECONNAISSANCE OF PART OF WESTERN ARIZONA.

petrographic character as those contained in the Temple Bar conglomerate (see p. 17) and were supposedly erupted at about the same 

time. For these reasons the detrital filling is correlated tentatively 

with the Temple Bar conglomerate.

GEOLOGIC HISTORY.

INTRODUCTORY STATEMENTS.

It is desirable to consider at this point the geologic history of the 

region to review the facts that have been presented and to emphasize 

their significance. Certain considerations which depend upon the 

interrelations of features at various localities are also presented without reference to former descriptions. The reader should be reminded 

again that the observations were made during rapid reconnaissance 

trips and that large intervening areas were not examined. With the 

exception of the Paleozoic formations of the Plateau region, none of 

the sediments of northwestern Arizona are fossiliferous so far as observed, and the younger formations can not be traced continuously 

from place to place. The history of the region is largely one of destructive processes, and the ordinary means of correlation are wanting. 

For these reasons, although the sequence of the events is apparently 

clear, their places in the geologic time scale can not now be definitely 

fixed. The observed facts show that the late geologic history of the 

region is separable into epochs comparable with those established in 

neighboring regions, but in the absence of adequate correlation data 

the intention is to emphasize the sequence of events, the provisional 

correlations being offered only as a working basis.

PRE-CAMBRIAN CONDITIONS.

Crystalline rocks. Throughout northwestern Arizona the oldest 

rocks are coarsely crystalline granites and gneisses. In the plateau 

to the east the granites underlie the Cambrian sandstone and are intersected by less coarsely crystalline intrusives.

Sedimentation. The pre-Cambrian sediments so extensively developed in the Grand Canyon region apparently once extended over western Arizona, and remnants of them remain at the northern end of the 

region near Virgin Canyon and from Williams River southward in the 

southern part of the area examined.

Base-leveling. Previous to the deposition of the Cambrian sediments there was a long period of erosion during which such sediments 

as may have been deposited in the eastern part of the region were removed by erosion and the underlying granites were base-leveled. The 

line representing this base-level may be followed in the cliffs from 

Grand Canyon to the southern end of the Juniper Mountains.
GEOLOGIC HISTORY. 57 

PALEOZOIC AND MESOZOIC CONDITIONS.

But little can be said of the history of this region during Paleozoic 

and Mesozoic time. Cambrian sediments, consisting of sandstone 

and shale (Tonto formation), underlie the plateau, and were probably deposited over a large part of western Arizona. No Ordovician 

or Silurian formations have been discovered, and the Devonian of 

Grand Canyon, described by Walcott,a was not identified in the area 

examined. The Carboniferous is represented by the Redwall limestone, which extends from the Mississippian into the Pennsylvanian, 

as previously shown in the description of rock formations (pp. 15-16). 

There is a limited exposure of Carboniferous strata younger than the 

Redwall in Iceberg Canyon, and Mesozoic formations occur east of the 

rim of the, plateau in a manner which suggests the probability that 

they originally extended westward over the region described. So far 

as known, however, no remnants of any of these formations remain 

west of the cliffs.

Little is known regarding the original extent of the older sedimentary formations in -western Arizona or of the circumstances attending their removal. Probably some of the erosion occurred during 

the Cretaceous period, as suggested by Gilbert, 6 but nothing was 

found to indicate what proportion of it was accpmplished in pre-Tertiary and what in early Tertiary time.

TERTIARY EVENTS.

Explanatory statement. No great amount of sediment was deposited within the area described during Tertiary time. The period was 

apparently one of uplift, volcanic activity, .and extensive erosion, but 

it is not known whether the uplift began with the Tertiary or before, 

nor can the Tertiary be confidently separated from the Quaternary. 

The sequence of events, based upon physiographic evidence, can be 

stated with some confidence, but the various epochs can not be confidently referred to established subdivisions of time.

Denudation. The erosion which removed the older sedimentary 

formations from western Arizona during early Tertiary and preTertiary time was evidently on an extensive scale. Whatever Paleozoic and Mesozoic sediments had been deposited were stripped off 

and the underlying granites deeply dissected previous to the eruption of the oldest effusives. The Eocene sediments extensively developed farther north in parts of the plateau region are apparently absent 

from western Arizona, and the extensive denudation may have been 

accomplished in large part during Eocene time.

a Walcott, C. D., Am. Jour. Sci., 3d ser., vol. 20, 1880, pp. 221-225.

b Gilbert, G. K., U. S. Geog. Surv. W. 100th Mer., vol. 3,1875, p't. 1, p. 134.
58 RECONNAISSANCE OF PAET OF WESTERN ARIZONA.

Eruption of andesite. The oldest effusive rock thus far found in 

western Arizona is the andesite in the vicinity of Gold Roads, a mining camp on Black Mesa, west of Kingman. The andesite rests upon 

granite and underlies an extensive series of rhyolites and younger 

andesites, but no further evidence of its age was obtained. It may , be a time equivalent of the great masses of andesite comprising the 

Pine Valley Mountains and resting upon the Eocene sediments in the 

southwestern part of Utah. These masses, according to Huntington 

and Goldthwaite, a were probably extruded at the close of the Eocene. 

The provisional reference of the Arizona andesite to the close of the 

Eocene is based on the fact that, in the general sequence of events ^ 

here described, its extrusion occurred between the period of early 

Tertiary erosion and the long period of base-leveling, during which 

part of the Mohave peneplain was formed. (See p. 59.) '

Orustal movements and erosion. Either during or shortly after the ( 

extrusion of the older andesites further uplift apparently occurred in ( 

western Arizona, followed by renewed erosion, which carried away 

much of the andesite and again exposed the granite. The Paleozoic 

sediments that formerly extended much farther to the west were 

eroded away at about the same time and the region reduced to a 

peneplain, parts of which are still preserved in the Truxton Plateau 

and in the plateau lying south of Iceberg Canyon, in which soft and 

hard layers alike are truncated. This may prove to be a part of the 

Mohave peneplain in southwestern Utah, which in the opinion of 

Huntington and Goldthwaite 6 was formed after the period of folding " 

of the early Miocene.0 ' \

Certain phenomena described by Spurr,d from Meadow Valley Canyon, a tributary of Virgin River in southern Nevada, strengthen this 

supposition. He describes a succession of rocks very similar to those ; 

found in northwestern Arizona. Extensive beds of rhyolite rest on 

an eroded surface of older rocks and are overlain by extensive deposits of conglomerate and soft sandstone which he refers with a query 

to the Pliocene, and these in turn are overlain by basalt and Pleistocene gravel. His description of the Pliocene (?) conglomerate and 

its position in the sections given indicate that it is probably equivalent 

to the Temple Bar conglomerate, which is here regarded as Pleistocene. Fig. 16 of Spurr's paper shows faulted Paleozoic sediments 

peneplaned and overlain by the conglomerate. This faulting may 

prove to be part of the early faulting of the Plateau region, and the 

peneplain beneath the conglomerate to be part of the Mohave peneplain, in which case the relations in Meadow Valley Wash would

a Huntington, Ellsworth, and Goldthwaite, J. W., The Hurricane fault in the Toquerville district, 

Utah: Bull. Mus. Comp. Zool. Harvard Coll., vol. 42,1904, p. 217.

6 Idem, p. 226.

c Idem, p. 222.

d Spurr, J. E., Descriptive geology of Nevada south of the fortieth parallel and adjacent portions of 

California: Bull. U. S. Geol. Survey No. 208,1903, pp. 139-148.
GEOLOGIC HISTORY. 59

correspond with those found in the Plateau region and would form 

another link in the chain of evidence that the pre-Quaternary course 

of Colorado River was through southern Nevada, to the north of the 

present canyon.

Eruption of rJiyolite and younger andesite. After the formation of 

the peneplain, extensive masses of rhyolite and andesite, in the form 

of tuff, breccia, and flow, were spread over its surface, filling the 

depressions and covering all but the higher parts of the land surface. 

Although largely removed by later erosion, these lavas still cover 

wide areas, such as Black Mesa, a large part of the Truxton Plateau, 

and the mesa in the vicinity of Kingman. These lavas occur also to 

the east beyond the area described, and far to the south, where they 

form Castle Dome and the Chocolate Mountains in southwestern 

Arizona.

In places where the rhyolites and younger andesites occur in more

or less regular horizontal beds, as near Kingman and in Black Mesa, 

they have a maximum thickness of about 3,000 feet. In more mountainous regions, as at the southern end of the Aquarius Mountains, 

they are apparently thicker. In other places, notably in the Truxton 

Plateau, they thin and disappear. The 'thickness of the rhyolites 

and younger andesites, and their areal distribution, indicate that 

they originally covered a large part of northwestern Arizona.

The time at which these great masses of igneous rock were extruded 

is not definitely known. It was after the Mohave peneplain had been 

formed, at least in large part, for the lavas rest upon the eroded surface. Furthermore, the amount of erosion which followed the extrusion of these lavas places this event far back in the Tertiary. For 

these reasons, and because of the evidence that the close of the Miocene was a time of mountain forming and of great volcanic disturbance in the Great Basin and the mountains west of it, the extrusions 

of rhyolites and younger andesites may be provisionally referred to 

the close of the Miocene.

Formation of the Grand Wash Trough. Sometime during the middle Tertiary, and apparently before the completion of the Mohave 

peneplain, the Grand Wash fault was formed, with a displacement of 

several thousand feet, giving rise to the Grand Wash Trough. This 

faulting probably corresponds to the early displacements of the Hurricane and other faults described by Huntingtoii and Goldthwaite,a 

and should not be confused with the faulting which accompanied the 

later uplift of the plateau.

Deposition of the Greggs breccia. At the north end of the region 

described local deposition followed the extrusion of the rhyolites and 

younger andesites. These sediments in the vicinity of Temple Bar 

lie unconformably beneath the Temple Bar conglomerate and consist

a Huntington, Ellsworth, arid Goldthwaite, J. W., op. cit., p. 220.
60 RECONNAISSANCE OF PART OF. WESTEBN AEIZONA.

mainly of angular fragments of rhyolite, but otherwise are similar in 

character and stratigraphic position to the Greggs breccia, which, as 

already stated, consists mainly of granitic debris. Both breccias 

antedate the present course of Colorado River, which has eroded into 

them. This correlation would tend to place the Greggs breccia in 

the Pliocene. On the other hand, the physiographic evidence does not 

seem to favor this correlation. The rhyolites, supposed to have been 

erupted at the close of the Miocene, rest upon the peneplain, a fact 

which tends to place the breccia in the Miocene. It is evident, therefore, that the determination of the age of the Greggs breccia must 

await further investigation.

Erosion of the Detrital-Sacramento Valley. A long period of erosion 

apparently followed the rhyolitic eruptions and succeeding accumulation of breccia, during which the Detrital-Sacramento Valley was 

excavated. Measured from the original surface now represented by 

the mesas on either side, this valley is 5 to 15 miles wide and 3,000 

feet deep, including the gravel filling. It extends from southern 

Nevada southward to Williams River, where it is apparently interrupted by a lava-covered plateau, but its real continuity is shown by 

the gravel-filling beneath the lava (fig. 16, p. 54). From the plateau 

southward it is occupied by Colorado River for a distance of 75 miles, 

in the basin known as the Great Colorado Valley. Owing to circumstances beyond the writer's control, the old valley was not traced 

south of this basin. It may be pointed out, however, that at the 

southern end of the basin the river turns abruptly to the east and 

passes in a narrow rock canyon through the Chocolate Mountains. 

The general trend of the old valley suggests that it may continue 

through the hills west of Chocolate Canyon, or perhaps bene.ath the 

lavas, and connect with the Gulf of Calfornia (including at that time 

the Salton Sink), which lies southwest of the Chocolate Mountains.

The origin of the Detrital-Sacramento Valley, although a matter 

of great interest, can not be fully described until more information 

is available. It is in a region of profound faulting and surface warping, and may have originated as a succession of depressed areas. 

But whatever its origin it is believed to have been occupied and 

greatly modified, if not wholly formed, by a stream of considerable 

size. The reasons for this belief are as follows:

The beds of volcanic tuff, breccia, and flow in the mesas on either 

side are composed of the same kinds of rock and are so disposed as 

to indicate that they may originally have been connected across the 

intervening space. The width of the valley, 5 to 30 miles, as compared with its length, about 375 miles (including the Great Colorado 

Valley),. together with its somewhat sinuous course, accords more 

nearly with the conception of a moderately mature river valley than 

with a succession of downthrown areas. But perhaps the strongest
' GEOLOGIC HISTORY. 61

 '- argument in favor of its formation mainly by river erosion is the 

presence, throughout its length, of sands and gravels similar to those 

known to have been deposited by aggrading streams.

v Relation of Colorado River to the Detrital-Sacramento Valley. The 

influence of Colorado River has not been considered thus far for the 

reason that no clear evidence has been obtained of its presence within

> the area described. The erosion previously accomplished may have 

been the work of the Colorado, or may have been accomplished by 

streams now extinct. °But with the erosion of the- Detrital-Sacra-

( mento Valley the recorded history of the Colorado in western Arizona

i apparently begins. The river changed its course within the area 

described during Quaternary time, and there are indications that

; still greater changes occurred in late Tertiary time; but in order to 

determine the nature and extent of the changes, it would be necessary 

to examine a large part of the Plateau region, where, on account of

\ recent faulting, uplift, and subsequent erosion, the investigation 

would be difficult. There was apparently no great difference in 

elevation between the Basin region and the southern part of the

' Plateau region during mid-Tertiary time, the Mohave peneplain 

extending continuously over both. The evidence of peneplanation 

in the Meadow Valley and in the Toquerville region, and the general 

trend of the broad valley of the Virgin heading into this region, 

suggest that the Colorado may have flowed across what is now the 

Plateau region to the north of its present course and through the 

valley now occupied by the lower part of the Virgin into western 

Arizona, where it excavated the Detrital-Sacramento Valley. A large 

part of Tertiary time must have been consumed in eroding this great 

. valley. If the formation of the peneplain be correctly assigned to 

the Miocene, and the extrusion of the rhyolites and younger andesites 

to the close of this epoch, the erosion of the Detrital-Sacramento 

Valley must have been accomplished in the Pliocene.

Uplift of the plateau. The Plateau region seems to have been 

not notably higher than the area west of it until the end of the epoch 

during which the Detrital-Sacramento Valley was excavated. But 

at this time it was greatly elevated and faulted. Extensive displacements occurred along its western border, forming the Grand 

Wash, Cottonwood, and Aquarius cliffs. Probably the tilting of 

the great crust blocks like that of the Hualpai Mountains occurred 

about the same time. The block at Iceberg Canyon, previously 

upturned, was again tilted, together with the overlying Greggs 

breccia. The Cerbat Mountains were probably uplifted to some 

extent, but the principal movement there seems to have been downward, forming Hualpai Valley. About 'the same time flows of 

basalt occurred in the Detrital-Sacramento Valley west of Chloride, 

in the Cerbat Mountains, and elsewhere, which may antedate the
62 RECONNAISSANCE OF PAET OF WESTERN ARIZONA.

crustal movements or may have occurred as accompaniments of the 

initial movements and later have been tilted to their present position.

Effect of uplift on Colorado River. The lines of faulting and the 

axes of uplift were developed across Colorado River and no doubt 

materially changed its course. Whatever this may have been 

previously, the uplift of the plateau finally established its direction 

by causing it to erode the Grand Canyon. In the low-lying region 

west of'the plateau the river flowed across the Grand Wash Trough, 

previously filled, with the Greggs breccia, across the truncated edges 

of the upturned sediments now exposed in Iceberg Canyon, across a 

second debris-filled trough near Hualpai Wash, through the crystalline 

rocks of the Virgin Mountains, and into the previously formed DetritalSacramento Valley, which it apparently followed thence to the sea.

The reasons previously given in the detailed descriptions for 

believing' this to be the river's former course may be briefly summarized as follows: Boulder and Black canyons west of the DetritalSacramento Valley are apparently younger than Virgin and Iceberg 

canyons. Remnants of the Temple Bar conglomerate, which occurs 

typically as the filling of the Detrital-Sacramento Valley, are found in 

Virgin and Iceberg canyons in positions that indicate deposition 

after these canyons were eroded; no such occurrence was observed 

in the canyons west of the Detrital-Sacramento Valley. There are 

gravel formations similar to the Temple Bar conglomerate west of the 

Black Mountain range, but they were apparently deposited previous 

to the erosion of Boulder and Black canyons.

QUATERNARY (?) EVENTS.

 First canyon cutting. During the first epoch of erosion that 

followed the uplift of the plateau Colorado River eroded Grand 

Canyon to a depth of 5,000 feet or more beneath the Mohave peneplain. West of the plateau it cut to a depth of somewhat more than 

1,400 feet beneath this plain in Iceberg and Virgin canyons. The 

erosion in the Detrital-Sacramento Valley was probably, correspondingly great, but little is known of this on account of the detrital 

filling of the valley which has not been removed.

The reasons for departing from the usage of former writers who 

assign the erosion of Grand Canyon to late Tertiary time are twofold: 

First, the Temple Bar conglomerate, deposited immediately after the 

first epoch of canyon cutting, is regarded as a Quaternary deposit for 

reasons stated in the section next following; second, the crustal 

disturbances resulting in the elevation of the plateau and the erosion 

of the Grand Canyon were of such magnitude and far-reaching 

influence in effecting radical changes in the geography and geology 

of the region that, considering this region alone, without reference to 

established subdivisions, they appropriately constitute the separation
GEOLOGIC HISTORY. 63

between two great periods of time. Since, therefore, the canyon 

cutting followed the uplift, it falls into the later or Quaternary 

period. '

Deposition of the Temple Bar conglomerate. After the canyon had 

been eroded to something like its present depth some change occurred 

which caused the river to deposit sand and gravel from Grand Canyon 

to the Gulf of California. Between the mouth of the canyon and the 

Detrital-Sacramento Valley no great volume of the gravels accumulated, owing to the limited dimensions of that part of the valley; 

but in the broad Detrital-Sacramento Valley extensive deposits 

were laid down to a depth of something like 2,000 feet.

Similar deposits were formed in other valleys of the Southwest, 

and the low-lying interstream areas were built up with angular 

rock debris derived from the near-by mountains. As previously 

described, the detrital formations of various parts of the Territory 

can not be definitely correlated, but beds apparently equivalent to the 

Temple Bar conglomerate are found throughout the Southwest.

During this epoch of deposition numerous volcanic eruptions 

occurred. Sheets of basalt underlie the gravels in some places and 

in others are included within them at several horizons. Toward the 

close of the epoch eruptions occurred near the mouth of Williams 

Kiver, the molten basalt bursting upward through the filling of the 

Detrital-Sacramento Valley and spreading over its surface to a depth 

of 800 feet or more, apparently forming a volcanic dam. This sheet 

has since been greatly eroded and its original extent has not been 

determined. Lava hills north of Williams River having the appearance of volcanic necks suggest that the center of eruption and the 

real obstruction across the valley may have been between the Mohave 

Mountains and the Aubrey Hills, the sheet of compact lava south of 

Williams River being an outflow from this center.

A dam 800 feet high thrown across Colorado River at this place 

would have created slack-water conditions not only throughout 

the entire length of the Detrital-Sacramento Valley, but far into 

Grand Canj^on, and must have facilitated the deposition of sand and 

gravel, which had previously accumulated in the valley to a depth of 

about 1,000 feet. The altitude of the basalt sheet does not differ 

greatly from that of the aggraded floor of the Detrital-Sacramento 

Valley to the north, and of the sand and gravel remnants found far 

above the.river in the walls of Virgin Canyon. . Deposition of sand 

and gravel apparently continued long after the extrusion of these 

lavas, filling the Detrital-Sacramento Valley to a level corresponding 

to the surface of the lava sheet, an additional depth of about 800 feet.

It is probable that the volcanic dam did not at once divert the 

river from its former course through the Detrital-Sacramento Valley, 

for the upper part of the valley filling, so far as observed, does not
64 RECONNAISSANCE OF PART "OF WESTERN ARIZONA.

differ in physical character from the lower 1,000 feet, which is presumably a river deposit. The coarseness of the sediment and the 

absence of terraces along the margin are unfavorable to the supposition that the valley was transformed into a lake separated from the 

river. It is more probable that the water of the river continued to 

flow through the temporary lake, filling it rapidly with sediment or 

even building above the level of the dam before being finally deflected 

from its former course. A general view of the aggraded valley floor 

and its relation to the neighboring hills is shown in PI. XI.

While accumulation was going on in the Detrital-Sacramento 

Valley other valleys and basins were filling with sediment. The Big 

Sandy, probably flowing at that time west of the Artillery Mountains 

and through the Cactus Plains to the Colorado, was evidently building up its course, and the Hualpai Valley, probably at first a lake 

basin, was filling with sediment. Briefly stated, it is probable that 

the Temple Bar conglomerate is a part of the widespread accumulation 

which occupies the low places of the Southwest from central New 

Mexico to California and northward over the entire basin region. 

The probability that sedimentation over a wide area was due to a 

single far-reaching cause or group of causes constitutes one of the 

principal reasons for correlating the Temple Bar conglomerate with 

the Lake Bonneville beds and less confidently with the Gila conglomerate. It is not the author's intention to argue that these beds 

are exact equivalents. They apparently belong, however, to a single 

division of time, like the Pleistocene epoch of the Quaternary.

It may not be out of place, furthermore, to reiterate the statement 

that the reconnaissance surveys were inadequate for the final solution 

of the broad problems which, on account of their local bearing, must 

of necessity be discussed. The age of the Temple Bar conglomerate 

and its relation to other similar deposits, the changes in the course 

and activities of Colorado River, and the causes of these changes, 

are all problems to be finally solved only after much more extended 

investigation.

River diversion. The extensive aggradation caused some of the 

streams to abandon their old courses, and the sand and gravel filling 

the valleys were in some cases covered with angular wash. A notable occurrence of the diversion of a river and the burial of its gravels, 

in the Salt River Valley, has been described by the writer,a who shows 

that Salt River, which now flows north of the Salt River Mountains, 

formerly joined the Gila east of these mountains, about 40 miles 

farther upstream.

Colorado River left the Detrital-Sacramento Valley and established 

a new course west of the Black Mountain Range, from Boulder Canyon

a Lee, W. T., Underground waters of Salt River Valley, Arizona: Water-Supply Paper U. S. Geol. 

Survey No. 136,1905, pp. 125-127.
GEOLOGIC HISTORY. 65

to the mouth of Williams River, a distance of about 125 miles. This 

diversion may have been due in part to the volcanic dam which had 

been thrown across the Detrital-Sacramento Valley near Williams 

 River; or it may have been caused wholly by the normal deflection 

of the river over the aggrading surface an action well illustrated in 

the frequent changes of course over the flood plains and delta of the 

Colorado at the present time. It is noteworthy in this connection 

that the volcanic dam near Williams Canyon, the highest remnants of 

the detrital beds, and the mountain ridges through which the river 

cut at Boulder and Black canyons, do not differ greatly in altitude.

Second canyon cutting. A second epoch of canyon cutting was 

brought about by some change which caused the streams throughout 

the Southwest to erode their channels. The streams which had not 

been deflected from their former courses reexcavated their old valleys; 

those that had been deflected cut new canyons. Colorado River 

reexcavated its old valley from Grand Canyon westward to the 

Detrital-Sacramento Valley, where it left its former course, passing 

westward across the Black Mountain Range and thence southward to 

the mouth of Williams River, where it returned to the old valley 

which it now occupies.

Viewed from the standpoint of existing topography, a more difficult course could scarcely have been selected. Instead of reexcavating the Detrital-Sacramento Valley, where the only hard rock to 

be eroded was the volcanic dam, it eroded four rock canyons (Boulder, 

Black, Mohave-, and Aubrey) and crossed four debris-filled basins 

(Las Vegas, Cottonwood, Mohave, and Chemehuevis) before returning to its former course. The excavation of the detritus in the basins 

was naturally more rapid than the work in the hard rock of the ridges 

separating them, and the result is the conspicuous alternation of 

short, sharp canyons and basin-like valleys characteristic of lower 

Colorado River.

During this epoch the downcutting was apparently very rapid, the 

rock canyons being narrow, their walls rising abruptly from the 

water's edge, as in Black Canyon (PI. VIII, J5) and in Boulder Canyon. The rapidity of the downcutting is perhaps most strikingly 

shown where the river has cut through the Temple Bar conglomerate, 

as at Temple Bar, leaving the poorly consolidated gravels standing in 

perpendicular cliffs hundreds of feet high. (See Pis. II and VIII, A.} 

The occurrence of these high cliffs of unconsolidated gravel and the 

absence of extensive weathering are not wholly in accord with the 

suggestion that the change from the aggrading to the degrading condition of the river was due entirely to a change of climate. " 

Deposition of OhemeJiuevis gravel. Some influence not certainly 

known brought the second epoch of erosion to a close and caused 

Colorado River and other streams of the Southwest again to fill their

49964 Bull. 352 08 5
66 RECONNAISSANCE OF PART OF WESTERN ARIZONA.

valleys with, sand and gravel. The open basins which had been 

excavated along the Colorado while the canyons were being cut in 

the harder rock were filled to a depth of several hundred feet with 

material which has been called the Chemehuevis gravel, and which 

extends from the mouth of Grand Canyon to the Gulf of California. 

In the midst of this epoch some change occurred which caused the 

accumulation of coarser material in the vicinity of Bull Head. This 

change, however, may have been local, as the division into lower and 

upper gravels is not conspicuous in other places, so far as observed.

During the accumulation of the Chemehuevis gravel Colorado River 

evidently shifted its course within narrow limits over the aggrading valley floor, as it had done over a much wider area during the 

accumulation of the Temple Bar conglomerate.

Third canyon cutting. When the river again began to erode its 

channel it reexcavated for the most part the old valley, but in a 

number of places abandoned its former course and cut rock gorges, 

leaving the gravel-filled channel at one side, as in Cottonwood Valley 

(p. 37), Pyramid Canyon (p. 38), Mohave Canyon (p. 42), and 

Chocolate Canyon (p. 48).

For a third time £he river eroded to some unknown depth below its 

present bed. Borings to a maximum depth of about 200 feet at the 

dam sites of the Reclamation Service failed to penetrate through the 

gravels.

Formation of flood plains. -In very recent geologic time Colorado 

River changed again from a degrading to an aggrading stream, and is 

once more building up its course. In the broad parts of the valley 

the accumulation is evidenced by the wide, bottom lands over which 

the river frequently changes its course, sometimes gradually by 

lateral cutting and filling, and sometimes suddenly by cutting a new

channel during a flood, forming numerous sloughs, lagoons, and

oxbow lakes.

The great depth of the debris-filled channels within. the newest 

canyons, as shown by the soundings for bed rock, raises the question, 

What proportion of the depth should be attributed to the normal 

cutting of the river and what proportion to permanent filling ?

Cooley 0 shows that Missouri River at Nebraska City probably 

erodes its bed to a depth of 70 to 90 feet. Near Omaha the depth of 

scour and fill during the year 1883 amounted to about 40 feet. On 

this subject Chamberlin b remarks: "In the drift-filled bottoms of 

the great branches of the Mississippi system it is wholly within bounds 

to regard at least the upper 40 or 50 feet of the deposit over which the

a Report Chief Eng. U. S. A. for 1879-80, pt. 2, pp. 1060-1071. See also Chamberlin and Salisbury, 

Text Book of Geology, vol. 1, p. 185. 

t> Chamberlin, T. C., Jour. Geol., vol. 11,1903, p. 72.
GEOLOGIC HISTORY. 67

river meanders as subject to scour and fill, and to entertain the suggestion that the deeper portions down to 100 feet or more may be 

similarly affected."

Some instructive data were secured during the construction of 

bridges across Mississippi and Missouri rivers. N. M. Fenneman" 

has made a special study of this subject and states that the depth of 

scour, as shown by the occurrence of buried wreckage and also by 

direct soundings, is 100 feet or more, and that the occurrence of 

gravels resting on freshly polished rock at a maximum depth of about 

335 feet is interpreted as showing that the river transports gravels of 

considerable size and actively erodes its bed to this great depth. It 

seems possible, however, that some part of this material may be due 

to permanent filling in a glacial or preglacial valley, such as are known 

to exist in the Mississippi Valley.

It is probable that the depth to bed rock shown by the soundings 

at the various dam sites is largely.due to the normal action of the 

river, cutting deep in times of flood and filling the channel at times of 

low water. It is equally probable, however, that the channel is to 

some extent permanently filled.

RESUME OF HISTORY.

For convenience of reference, the succession of epochs and their 

possible time relations are tabulated below.

Table of events in geologic history in 'western Arizona.

.Period.

Quaternary

0

>,

03

01

EH

Epoch.

I'liiistoeene .. .

 ? 

Miocene. .....

Eoceno. ......

Deposition epoch.

in illation still in progress. 

/.LO. ....................................

9. Deposition of the Chemehuevis 

gravel. 

8... ...................................

7. "Widespread aggradation and volcanic eruption. About 2,000 

feet of the Temple Bar conglomerate deposited. 

0......................................

[4. Local deposition; eruption of 

1 rhyolite and andesite. { -------- - ---

(2. Eruption of andesite. . 

\l... r ... ...............................

Erosion epoch.

reexcavates old valley in part and 

cuts several short rock gorges.

River, flowing west of the Black 

Mountains, lowers its bed 2,000 feet 

or more and cuts Aubrey, Mohave, 

Black, and Boulder canyons.

sion of Grand Canyon; flow of Colorado River in the DotritaJ-Sacraniento Valley.

 ? 

and other valleys.

Yarapai Cliffs.

a- Personal communication.
68 RECONNAISSANCE OF PART OF WESTERN ARIZONA. v

CORRELATIONS.

Explanatory statements. Although no definite correlations can be c 

made between the products of deposition and erosion of this and other v 

regions, there are certain presumptions worthy of consideration. The 

succession of Quaternary events in western Arizona is similar to that 

of the Lake Bonneville and other inland regions, and the long epochs v 

of erosion and thick deposits of sediment represent comparable lengths 

of time for each region. Western Arizona is a part of the great area 

of western America which underwent extensive changes of elevation 

during Tertiary and Quaternary time, the various epochs of which 

were recorded in marine deposition and erosion along the Pacific "* 

coast. Since western Arizona is a part of the Pacific drainage area, 

although far inland, it is presumably true that the great epochs of , 

the coast correspond in some measure with the. great epochs of the 

interior, inasmuch as the thick marine deposits must represent long \ 

periods of erosion of the land areas.

Comparison with Lake Bonneville history. In his summary of the 

history of the Lake Bonneville oscillations Gilbert a enumerates the 

following events, given in order from oldest to youngest:

1. Erosion. Gilbert says: "This we may call the pre-Bonneville ** 

low-water epoch. It was of great duration compared with those 

enumerated below."

2. Deposition. First B.onneville epoch of high water; deposits of 

Yellow Clay. This epoch is estimated (p. 316) as being five times 

as long as the second epoch of deposition (4).

3. Erosion. Represented by unconformity and by alluvial deposits. 

The duration is estimated (p. 316) as greater than that of the final \£ 

retreat of the water (5).

4. Deposition. Second Bonneville epoch of high water; deposit of 

White Marl. -

5. Final retreat of water, intermittently, to present stage.

The thickness of the Lake Bonneville beds was not known at the 

time of Gilbert's writings, nor is their maximum thickness yet ^ 

determined. Boutwell b has shown that a 2,000-foot well at the 

eastern margin of Salt Lake, near Farmington (altitude 4,231 feet), 

does not penetrate through the fragmental beds. A similar thickness < 

of sediments has recently been found in a deep, boring at Neels, Utah 

(altitude 4,621 feet), a station on the San Pedro, Los Angeles and 

Salt Lake Railroad east of Sevier Lake. The well, which was com- > 

pleted in 1906, is 1,998 feet deep and penetrates 1,944 feet of sedimentary matter before reaching bed rock, which is granite.

« Gilbert, G. K., Lake Bonnevillu: Mon. U. S. G.e.o.l. Survey, vol. 1,1890, p. 259. 

''Boutwell, J. M., Oil and asphalt prospects in Salt Lake basin: Bull. U. S. Geol. Survey No. 2(30, 

1904, p. 471. . '"-
GEOLOGIC HISTORY. 69

A driller's record, which was apparently kept with exceptional care, 

exhibits no change in character to indicate that the lower part of the 

beds are pre-Bonneville in age. It is worthy of note that Neels is 

located in the narrow neck of Lake Bonneville that connected 

Escalante Bay-with the larger body of water to the north, as shown 

in Gilbert's map (PL III of the Lake Bonneville monograph). It is 

probable that the broader parts of the lake were much deeper than 

this narrow strait, and that the sediments filling them were correspondingly thicker. 

Because of the importance of this well in showing the character 

and depth of the Lake Bonneville sediments, the driller's record is 

here given:

Record of San Pedro, Los Angeles and Salt Lake Railroad well at Neels, Utah.

Thickness Depth 

(feet), (feet).

Surface soil......................................................... 4 4

Sedimentary (alkali)............................................... 5 . 9

Fire clay......................................................... 40 49

Water-bearing quicksand........................................... 9 58

Shale and soapstone............................................... 21 79

llock (sedimentary)................................................ G 85

Water-bearing quicksand........................................... 3 88

Soapstone.......................................................... 11 99

Soapstone with fossil bowlders....................................... 39 138

Water-bearing quicksand........................................... 4. 142

Fire clay......................................................... 12 154

Blue waxy clay..................................................... 34 188

Gray shale and clay mixed......................................... 7 195

Gray waxy clay.................................................... 36 231

Lava rock......................................................... 12 243

Blue waxy clay................................................... 12 255

Sedimentary sandstone............................................. G 261

Blue waxy clay................................................... 25 286

Water-bearing quicksand........................................... G 292

Blue waxy clay.................................'.................. 28 320

Water-bearing quicksand........................................... 7 327

Sedimentary sandstone............................................. 10 337

Yellow clay....................................................... 16 353

Water-bearing quicksand........................................... 5 358

Yellow clay....................................................... 27 385

Blue waxy clay................................................... 110 4.95

Yellow clay....................................................... 15 510

Sedimentary sandstone............................................. 24 534

Blue waxy clay................................................... 17 551

Soapstone.......................................................... 50 GOJ.

Blue waxy clay................................................... 11 612

SUt............................................................... 8 620

Water-bearing quicksand........................................... 3 623

Yellow clay........................................................ 53 676

Sedimentary sandstone.............................................. 12 688
70 RECONNAISSANCE OF PART OF WESTERN ARIZONA.

TliickYellow clay. .............................................

Blue waxy clay. .......................................

Yellow clay. ...........................................

Blue waxy clay. .......................................

Blue shale (sand mixed) .................................

Blue waxy clay. .......................................

Blue shale. .............................................

Blue shale (sand mixed), yielded hot water. ..............

Red shale. ..............................................

Blue shale. .............................................

Red shale. ..............................................

Blue shale. ............."................................

Red " keel" stone. ......................................

Water, sand, gravel, and bowlders. .......................

Sedimentary sandstone (brown) .........................

Red sandstone. .........................................

Red shale (burned) .....................................

Trap rock (dark brown) ..................................

Red 'shale (burned). . ...................................

Lava rock with calcite crystals. ...........................

Red sandstone. .........................................

Red clay (sticky) .......................................

Volcanic deposit, ash, and bowlders. ....................

716SS

(feet).

............ 34

............ 117

........... 9

........... 210

........... 18

........... 13

........... 45

........... 71

........... 12

........... 70

........... 24

........... 28

........... 6

........... 70

..:........ 35

........... 95

........... 35

........... 36

........... 56

........... 14

........... 68

........... 48

........... 105

Depth

(feet).

722

839

848

1,058

1,076

1,089

1,134

1,205

1,217

1,287

1, 311

1,339

1,345

1,415

1,450

1,545

1,580

1,616

1,672

1,686

1,754

1,802

1,907

(Gas under pressure sufficient to raise 6,200 pounds of tools 400 feet.)

Bowlders (cemented)............-. .................................. 6 1,913

Cavity. ............................................................ 9 1, 922

Bowlders. ......................................................... 22 1, 944

Cavity. ............................................................ 6 1, 950

Granite with cavities and gas ...................................... : 48 1, 998

1,998

At the risk of carrying comparisons too far, attention is called to 

the possible correspondence between the Quaternary epochs of 

western Arizona and those of the Lake Bonneville basin. The high 

stages of Lake Bonneville have been explained as being due to the 

changes of climate toward increasing precipitation, and the lowwater stages toward increasing aridity. Periods of great precipitation 

(and high water in an undrained lake) are those of active stream 

erosion, and, other things being equal, the periods of sedimentation 

in Lake Bonneville should be the periods of stream erosion in neighboring regions. On this assumption Gilbert's first Bonneville epoch 

of high water, during which 2,000 feet or more of sediment consisting 

largely of fine material was deposited, seems to correspond in duration and position in the time scale to the erosion of Grand Canyon 

(epoch 6 of the Arizona scale); his first epoch of low water, to the 

deposition of the Temple Bar conglomerate; his second Bonneville 

epoch of high water, to the erosion of Black and Boulder canyons 

(epoch 8 of Arizona); and his final epoch of desiccation, which was
GEOLOGIC HISTORY. 71

accomplished intermittently, to the deposition of the Chemehuevis 

gravel and the following minor epochs represented along lower Colorado River. Whether so close a parallelism of events is warrantable 

or not, it is evident that the general sequence of events as recorded 

in the Bonneville basin is similar to that of the Colorado Valley.

Comparison with, southern California. Hershey a has arrived at a 

conclusion regarding the length of Quaternary time and the complexity of its history which is similar in a general way to that shown 

by the epochs of the Bonneville basin and of western Arizona. Probably the most significant feature of his subdivisions in relation to the 

phenomena of western Arizona is a long epoch of erosion at the beginning of the Quaternary, which in his opinion is much longer than all 

the subsequent epochs combined. This epoch may, on further 

study, prove to be equivalent in point of time to the erosion of Grand 

Canyon.

Comparison with the Pacific coast. In studies of the marine beds 

of the Pacific coast, Arnold b shows that, while the epochs of the Tertiary and Quaternary are very fully represented, the subdivisions do 

not conform in all cases to those of the standard time scale. The 

division of Tertiary time as given in his publications, which in personal interviews he asserts will hold good for the Pacific coast generally, is shown in the following table:

Correlation table of the marine Tertiary and Pleistocene formations of the Pacific coast.

Period.

Tertiary...............

Epoch. Formation. c

San Pcdro, 1,000 ± feet.

Merced, 5,000 ± feet. .

Purisima, 800 ± feet.

San Pablo, 1,500 to 2,000 feet.

Monterey, 2,500 ± feet.

Vaqueros, 3,000 ± feet.

San Lbrenzo, 2,300 ± feet.

Tejon, 4,000 ± feet.

 Martinez, 1,000 to 2,000 feet.

a Hershey, O. H., The Quaternary of southern California: Bull. Univ. California Dept. Geol., vol. 3, 

1902, pp. 1-30.

 b Arnold, Ralph, The Tertiary and Quaternary pectens of California: Prof. Papar U. S. Geol. Survey 

No. 47, 1906, p. 9.

'cln this column full linos represent unconformity; broken lines, conformity.
72 RECONNAISSANCE OF PABT OF WESTERN ARIZONA.

According to Arnold, the great time breaks occurred: (a) At the 

close of the Eocene, the break in this case being indicated by a distinct 

change of fauna; (b) before the close of the Miocene; and (c) sometime during the Quaternary; the latter two being erosion breaks. 

It seems probable that the long periods of sedimentation along the 

Pacific Coast may be equivalent in a general way to the periods of 

quiet erosion described in western Arizona, and that the great and 

widely recognizable unconformities of the coast may correspond to 

the periods of crustal disturbances and volcanic activity of the 

interior. Thus the long period of erosion resulting in the formation 

of the Mohave peneplain may correspond to the deposition of the 

Vaqueros and Monterey formations, and the eruptions of rhyolite in 

Arizona to the unconformity between the San Pablo and the Monterey, which is associated with, the volcanic eruptions of the coast 

region.

The similarity in succession of Quaternary events in the two 

regions is not striking. Pleistocene time is represented on the coast 

by thick sediments and Recent time by some of the raised sea beeches. 

The thickness of the Pleistocene sediments renders it probable that 

the time required for their deposition is comparable with the long 

period of erosion during early Quaternary in the Arizona region, and 

the relative position of these epochs in the time scale apparently warrants provisional correlation. The terraces of the coast may correspond in time with the various epochs of erosion and deposition of 

the Arizona region.

Comparison with the Plateau region. In the Plateau region the subdivision of Tertiary and Quaternary time is based mainly on physiographic evidence. Davis a has shown that there were two main 

cycles of erosion, designated the plateau cycle and the canyon cycle. 

During the first or plateau cycle a large area in northern Arizona and 

southern Utah was reduced to a peneplain. The original surface of 

this peneplain is preserved in places by lava flows, as on the Shiwitz 

Plateau in northern Arizona and near Toquerville, Utah, b but has 

generally been dissected by later erosion. The peneplain will perhaps be best recognized if due allowance be made for subsequent 

erosion as the surface of the plateau in which Grand Canyon is 

eroded in northern Arizona. During the second or canyon cycle 

Grand Canyon was carved by the Colorado, and the peneplain, now 

elevated, was dissected to a less extent by the smaller streams.

Following Davis, Huntington and Goldthwaite in their description 

of the Toquerville region of southwestern Utah emphasize the importance of these cycles and add many details which aid in studying

a Davis, .W. M., An excursion to the Grand Canyon of the Colorado: Bull. Mus. Comp. Zool. Harvard 

Coll., vol. 38, 1901, pp. 107-201.

& Huntington, Ellsworth, and Goldthwaite, J. W., The Hurricane fault in the Toquerville district, 

Utah: Bull. Mus.Comp. Zool. Harvard Coll., vol. 42,1904, p. 231.
GEOLOGIC HISTORY. 73

the geologic history of the Grand -Canyon region. The succession of 

Tertiary and Quaternary events described by them may be summarized, in order from oldest to youngest, as follows:

1. Eocene. A period of deposition during which the Plateau 

region was low.

2. A period of elevation accompanied by folding, flexing, and 

extrusion of andesite.

3. A second period of erosion the pre-fault Cycle.

4. Earlier faulting, during which the great faults of the Plateau 

region, such -as Hurricane, and Grand Wash faults, were originally 

formed.

5. Interfault cycle of erosion, during which the Mohave peneplain 

was formed.

6. Later faulting and final uplift of the High Plateau.

7. Erosion of Grand Canyon.

The history thus developed corresponds in many ways with that 

of western Arizona, but differs notably in some respects. The early 

Tertiary erosion in western Arizona seems to correspond in. time 

with the Eocene sedimentation of the plateaus, and eruptions of 

andesite marked, the close of the period of both, provinces. There 

is, furthermore, no disagreement regarding the time of uplift and 

faulting immediately preceding the erosion of Grand Canyon, but 

further investigation is necessary before the subdivision of middle 

and later Tertiary time in the two provinces can be harmonized. 

Apparently, the great masses of rhyolite, 3,000 feet thick in western 

Arizona and presumably extruded at the close of the Miocene, were 

not found in southwestern Utah, and the long period of erosion which 

followed their extrusion, presumably during Pliocene time, seems to 

be included by Huntington and Goldthwaite in the time during 

which the Mohave peneplain was being formed, since according to 

them this cycle of erosion ended, with the uplift of the plateau and 

the origin of Grand Canyon.

Since the Mohave peneplain is here used as a correlation horizon, 

it may be in place to inquire into its probable extent. As already 

stated, this peneplain,'which in the Plateau region of southern Utah 

and northern Arizona is represented, by the platform at the top of 

Grand. Canyon, is here regarded as extending generally over northwestern Arizona. A similar peneplain has been described by Lindgren ft in the Sierra region of eastern California, where he finds evidence of an extensive peneplain, formed presumably during the 

Miocene and covered in part by the younger auriferous gravels, and 

these in turn by rhyolites and andesites a sequence which corresponds with that in northwestern Arizona. Other localities might

"Linclgren, Waldemar, Age of the auriferous gravels of the Sierra Nevada: .Tour. Geology, vol. 55, 

1890, pp. 881-900.
74 .-RECONNAISSANCE OF PART 01? WESTERN ARIZONA.

be referred to in which mid-Tertiary erosion may correspond in time 

with the formation of the Mohave peneplain. In view, however, of 

the great distances between the various localities described and the 

difficulties of correlating periods of erosion, the most that can be said 

is that the available evidence points to the probability that the 

Mohave peneplain was one of great extent and may prove to be a 

valuable means of correlation.

WATER SUPPLIES.

SURFACE WATERS. 

PRECIPITATION.

Little is definitely known of the rainfall in western Arizona. According to E. C. Murphy,a of the U. S. Geological Survey, the average 

annual precipitation- for the region is approximately 5 inches. At 

Needles, Cal., records kept by the Weather Bureau since 1892 show 

an annual mean of 2.47 inches.

EVAPORATION.

Evaporation in western Arizona greatly exceeds rainfall. No 

records are available for the area described, but it probably does not 

differ very much from that at Yuma, Ariz., where the annual evaporation, as given by Murphy, is 82.32 inches.

STREAMS. 

COLORADO RIVER.

Flow. A gaging station has recently been established at Hardyville, near old Fort Mohave, for measuring the flow of Colorado 

River. Records, however, are already available for the last four 

years at Yuma, Ariz., which probably give most satisfactorily the 

volume carried by the lower Colorado.

.Discharge of Colorado River at Yuma, Ariz.

1902.:..............................................................:..........

1903.......................:...................................................

1904...........................................................................

1905. ..........................................................................

A.vorft£ro

Total in 

acre-feet.

7,960,189

11,329,032

10,109,004

19, 710, 000

12,277,056

Mean in 

second-feet.

10,970

15,595

13,922

27,300

16 947

Irrigable lands. Although a large amount of water is available in 

Colorado River, the irrigable land is limited in amount and confined

a Personal communication.
WATEB SUPPLIES. 75

to the flood plains. According to Homer Hamlin,rt of the Reclamation Service, the acreage is distributed as follows:

Imyable land along Colorado River.

Acres. 

Cottonwood Valley...................................................... 5,000

Mohave Valley............................................................. 50,000

Chemehuevis Valley....................................................... 20,000

Great Colorado Valley.................................................... 200, 000

Yuma Valley........................................................... 100, 000

375, 000

The ways and means of irrigating these lands have been investigated by the Reclamation Service, but except for the Yuma project, 

now under construction, no development has yet been undertaken.

Outside of the flood plains no lands within the area described are 

sufficiently low to be irrigated from the river. The broad valleys 

and detrital plains occupying so large a part of ; the region, although 

admirably adapted to agriculture in other respects, are too high to 

be economically suppled with water from Colorado River by any 

means known at the present time. In order to water the Hualpai or 

Detrital valleys it would be necessary to raise the water of the river 

about 2,000 feet, and the case is nearly as hopeless for the valleys 

farther south.

Dam sites. Several dam sites have been selected along Colorado 

River by the engineers of the Reclamation Service, and much has 

been done in the way of investigation as far north as the Cottonwood Valley. Possible dam sites occur in Chocolate Canyon (fig. 

13), Aubrey Canyon, at Bulls Head in Pyramid Canyon (PL IX), 

and at Eagle Rock in the Cottonwood Valley (fig. 7). In none of 

these localities, however, has bed rock been found sufficiently near the 

surface to warrant the construction of masonry dams. In Chocolate 

Canyon borings reached the depth of 138 feet; in Aubrey Canyon, 

75 feet; in Pyramid Canyon, 100 feet. But in no case was the maximum depth of the old gravel-filled channel reached.

The canyons north of the Cottonwood Valley offer excellent opportunities for the construction of dams, but little has been done further 

than, the selection of certain favorable localities. Several have been 

selected by the Reclamation Service, and others by private companies who contemplate using the water power in developing the mineral resources of the region. The questions involved are mainly of 

an engineering nature, but it may be in place here to describe certain 

geologic conditions that are likely to affect development.

In Recent time the last epoch described under "Geologic history" the river has been filling its channel, at least in its lower

« Personal communication.
76 RECONNAISSANCE OF PART OF WESTERN ARIZONA.

reaches. It is evident, therefore, that even in the newest channels, 

such as that at Bulls Head, bed rock is not to be expected as near 

the surface as it would be if the river were in an eroding stage. In 

other words, it is probable that the rock .channel is deeper than the 

maximum depth of scour.

The flood-plain deposits, so conspicuous in the lower reaches of the 

river, become less conspicuous upstream, until in Black Canyon rapids 

of notable proportions occur. In the absence of soundings in the 

channel for bed rock farther north than Bulls Head, it is impossible 

to say that the channel is not filled in the northern portion of the 

region as it is farther south where soundings have been made. The 

swift current washes the fine material away and leaves large bowlders 

clogging the channel even where the grade of the river is steep enough 

to form dangerous rapids. It is the writer's impression that the 

river is flowing essentially on rock bottom through Black, Boulder, 

Virgin, and Iceberg canyons, with only such obstructions of bowlders 

as are incidental to variations in the river's power of transportation; 

in other words, that there is no permanent filling in the bottom of 

those canyons.

The deflection of the river previously described has resulted in. the 

cutting of young channels in many places for short distances, as at 

Eagle Rock, Bulls Head, Great Bend, etc. It is in these young channels that bed-rock is to be expected at the least depth. The relation, 

however, to the old debris-filled channel at the side may be such as 

to influence this depth. For example, at Bulls Head the depth to 

bed rock in the channel now occupied by the river might be greater 

near the edge of the old channel, owing to the fact that the new 

channel might coincide with some lateral wash of the old, while north 

of Bulls Head Rock, midway of the young channel, bed rock might 

be much nearer the surface. The depth to which a large river works 

is known to be great, although there is little information at present 

to indicate the maximum depth to which Colorado River works. The 

records of Missouri River, previously cited (p. 66), indicate the 

possibility that a depth of 73 to 100 feet, or even more in narrow 

channels, such as that at Bulls Head, is to be expected as a result of 

river abrasion alone.

Considering further the depth of scour, it is evident that the river 

will cut to a less depth in wide passages than in narrow passages 

where the current is swift. The narrow places are usually selected as 

dam sites on account of the presence of favorable abutments comparatively close together. It is possible that in certain cases the 

depth to bed rock in the wide part of a gorge, where the abrasive force 

is weak owing to a diminution of velocity, might be enough less than 

in the narrow parts, where the current is swift, to more than compensate for the greater length of a dam.
WATER SUPPLIES. 77 

BIG SANDY WASH AND WILLIAMS RIVER.

Big Sandy Wash has a small permanent flow, and Williams River 

furnishes water for the irrigation of a few ranches, but the floods of 

Williams River are evidently large. Water marks on the rocks and 

drift material lodged in the face of the canyon walls are seen at the 

height of 20 feet or more above the bed of the stream. The quantity 

of water discharged by Williams River is apparently sufficient to 

warrant the construction of a reservoir in the basin east of Williams 

Canyon. This basin is about 7 miles long and 5 miles wide, and the 

gorge forming a possible dam site is about 60 feet wide at the water 

line.

A reservoir at this place would be of comparatively little use in 

irrigation, as there is practically no irrigable land available. It 

might, however, be of great benefit in producing power for the development of the mineral resources. Rich deposits of gold, copper, and 

iron are known to occur in this region, but development is hindered 

or wholly prevented by the want of transportation facilities. The 

production of power, such as seems possible in this locality, might 

be the means of developing a rich mining district.

UNDERGROUND WATERS. 

SUKFACE INDICATIONS.

In many places throughout the Southwest the unconsolidated deposits filling the old valleys and intermontane basins are saturated with 

water, and the hope was entertained that this might be the case in 

the area here described. The geography of the region, however, is 

not favorable for the accumulation of large quantities of underground 

water, nor for the retention of such as might accumulate. The rainfall is slight and no large quantities can be derived from streams. 

Colorado Canyon on the north and west forms an effectual outlet for 

waters which might otherwise accumulate in the gravels.

From surface indications the Hualpai Valley would seem to have 

an underground water supply. It is an undrained basin into which 

Truxton Creek empties, and contains standing water for considerable 

periods. Only one well has been bored in the valley, at its northern 

extremity in Hualpai Wash. The absence of water in this well is not 

considered proof that water may not exist near the surface in the 

center of the valley.

In the other valleys and plains of the region the prospect is not 

encouraging. There is little opportunity for the accumulation of 

water in the gravels of the Cactus Plains, because of drainage into 

Colorado River to the west and Williams Canyon to the north. Conditions in the McMullen Valley are slightly more favorable, but water 

is found only at depths of 100 feet or more. No wells are reported 

from the plains south of Harrisburg.
78 KECONNAISSANCE OF PART OF WESTERN ARIZONA. ^

WELLS.

Nelson. The well at Nelson, Ariz., is 1,043 feet deep. At 516 

feet a little water was found, and in the sandstone near the bottom v 

a larger supply was encountered; but the available quantity has 

not been ascertained. The formations passed through are as follows:

Log of'railroad well at Nelson, Ariz.

Feet. 

Cemented detritus...................................................... 0- 44

Limestone (Redwall).................................................. 44- 396 ,

Sandstone and shale (Tonto)............................................ 396-1,043

Peach Springs. A well at Peach Springs, Ariz., is 920-feet deep. s 

A small amount of water was encountered somewhere in the lower 

half, but the horizon is not known. Water stands at a depth of 413 

feet, and a preliminary pumping test yielded 25 gallons per minute, ~* 

or 14,000 gallons per day of twenty-four hours. This is insufficient 

for railway use, and the well is to be sunk deeper^ The formations 

passed through are as follows:

Log of railroad well at Peach Springs, Ariz.

Feet.

Cemented gravel....i................................................... 0-200

Limestone (Redwall).................................................... 200-560

Shale (Tonto).............................................................. 560-920 '

Hackberry. There are several dug wells at Hackberry, Ariz., in 

or near the bed of Truxton Creek. They-penetrate through the detritus and encounter granite at a depth of about 70 feet, where a 

limited flow of water is obtained. The. well at the railway station is 

taxed to its extreme limit in supplying 80,000 gallons in twenty-four 

hours, or 55 gallons per minute.

Kingman. There are about 60 wells in the town of Kingman. A 

few of these are dug, but most of them are drilled. They are from 

120 to 200 feet in depth, according to the difference in surface elevation. The water occurs in a bed of volcanic tuff about 30 feet thick, 

which rests upon the granite. An abundance of water is obtained 

from these wells to supply the needs of the railroad and the town.

Gold Basin. Two wells 500 and 700 feet deep were drilled several 

years ago in Gold Basin at the northern end of the Hualpai Valley, 

about 50 miles north of Kingman. Nothing but detrital material 

was penetrated, and no water was encountered.

Drake. The well at Drake, in the Sacramento Valley, is 687 feet 

deep and penetrates to bed rock. Water was encountered at a depth 

of 430 feet in "gray granite" and rose 30 feet. (This material is 

undoubtedly granitic wash, cemented by carbonate. of lime. Cemented material of this kind is common in the Quaternary deposits 

throughout the arid regions. The yield of the well has not been 

determined.
WATER SUPPLIES. 79

Log of railroad well at Drake, Ariz.

Feet. 

Sand and bowlders. ..................................................... 0- 45

Brown sand. . ............................................................ 45- 90

Bowlders. ............................................................... 90-160

Brown sand. ............................................................. 160-178

Sand and gravel. ......................................................... 178-223

Black lava. .............................................................. 223-308

Yellow sand. ........................................................... 308-368

Black lava. .............................................................. 368-408

Flint. ................................................................... 408-414

Black lava. .............................................................. 414-419

Gray granite. ........................................................... 419^175

Black lava. .............................................................. 475-483

"Gray granite, " water bearing. .......................................... 483-537

Clay. ................. .^................................................. 537-578

Disintegrated granite. ................................................... 578-603

Solid granite. ........................................................... 603-687

Yucca. There are two deep wells at Yucca, situated near Sacramento Wash. The first was drilled in 1889 and has been in operation since that time. The amount of water obtainable was not 

sufficient for the needs at that point, and a second well has been put 

down to a depth of 1,004 feet. Water is said, to have been encountered at a depth of 310 feet, but when measured by the writer in the 

new well it was standing at a depth of 346 feet. No special waterbearing' stratum was encountered below the first, and the additional 

supply is obtained by slow seepage through the sand and gravel. The 

material encountered is as follows :

Log of railroad 'well at Yucca, Ariz.

Feet. 

Cemented sand and gravel. . ........................................... 0- 370

Clay................................................................... 370- 455

Gravel. .....................'.................................:......... 455- 555

White sand. . ........................................................... 555- 905

Granite. ............................................................... 905-1, 004

t. The well at Haviland is 505 feet deep and is in volcanic material most of the way. Water was encountered at a depth 

of 248 feet and rose 48 feet. The well yields 60,000 gallons of water 

per day, or about 42 gallons per minute. The material penetrated 

is as follows:

Log of railroad well at Hamland,, Ariz.

Feet. 

Bowlders. . . . . . .. .......: ................................................. 0-12

Lava. .................................................................. 12-260

White volcanic tuff. ..................................................... 260-505

Big Sandy Valley. Several wells dug in Big Sandy Wash encountered water 15 to 75 feet below the surface, according to locality. It 

is reported that a few years ago water was sufficiently near the surface to seep into the lower places along the bottom of the valley,
80 RECONNAISSANCE OF PART OF WESTERN ARIZONA.

where it was used for irrigation; but during the last few years this 

seepage has disappeared.

Harrisburg. Near Harrisburg, at the point where the wash draining the McMullen Valley passes through the constriction between 

the mountains, a centrifugal pump has been established, and water 

is obtained in sufficient quantities to irrigate a small ranch. This 

supply is local and limited in amount.

Other wells. At a number of places in McMullen Valley, in the 

Cactus Plain, and in the plains of the southern extremity of the region, 

wells were reported; but nowhere was ground water encountered in 

sufficient quantities or near enough to the surface to warrant any 

attempt at development for irrigation.

Records of railway wells in northeastern Arizona.

Location.

Hackberry. ....

Depth.

Feet. 

505

534

1,004

120-200

684

70 

920

1,043

Diameter.

Inches. 

12

10

13

Dug.

12

Dug. 

13

13

Year 

completed.

1901

1889

1903

(?)

1901

(?) 

1903

1902

Depth 

to 

water.

Feet. 

200

346

346

(?)

400

66 

413

490

Water raised byAirlift........

.....do........

.....do........

Airlift........

Steam pump . 

.....do........

Amount 

raised in 24 

hours.

Gallons. 

60, 000

a 90, 000

80,000 

14,000

Remarks.

is all that can now 

be pumped.

be sunk deeper.

feet.

a When tested. 

DEEP-WELL TEMPERATURES.

Temperature readings taken at two of the deep wells are given in 

the following table. The results obtained at Yucca are probably 

more satisfactory than those at Nelson, as conditions were more 

favorable for satisfactory observation. At Nelson the thermometer 

was not in the water at the upper horizon tested, while at Yucca it 

was under water at both horizons. The increase of' temperature 

downward in the Yucca well was 1° F. for 55 + feet. That in the 

Nelson well was 1° F. for 68+ feet.

Temperatures of water in 'wells at Yucca and Nelson, Ariz.

Location.

- Do....................

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

Surface 

elevaFeet.

1,804

1,804

5, 200

5,200

Total 

depth.

Feet.

1,004

1,004

1,043

1,043

Depth to 

water.

Feet.

346

346

490

490

Date of observation.

Sept., 1903...

.....do.......

.....do.......

.....do.......

Surface.

temperature at 

time of

observation.

°F.

98

98

75

Depth

at which 

temperature

was

taken.

Feet.

.1.004

455

1,040

200

Temperature.

°F.

90. 5

80.6

73.4

61.2

« General region volcanic. Drilling suspended three months previous to observation.

& In limestone region at edge of plateau. No work done on well for several months previous to time of

observation.
NOTES ON.THE'IGNEOUS ROCKS OF WESTERN ARIZONA,"

By ALBERT JOHANNSEN.

PRE-CAMBRIAN CRYSTALLINES.

The oldest of the volcanic rocks in northwestern Arizona are granites 

(A-6, A-44). 6 According to Lee, they occur below the effusives

throughout the entire area, and in the cliffs to the east are overlain 

by the same series of Cambrian rocks which in the Grand Canyon 

section is called the Tonto formation. Over the whole area the fact 

that the granite is an older and not a younger intrusive is clearly 

indicated by the occurrence of dikes and veins within it which do not 

extend through the overlying rocks. The upper surface was planed 

nearly to a base-level and the effusives generally overlie it in horizontal sheets.

Much granite occurs in the area. The rock is red to gray in color, 

is usually coarsely crystalline, and is much cut by dikes and veins. 

Here and there in faulted regions, the rock is highly gneissoid, while 

in other places the mass passes, by easy transitions, from the normal 

rock to the schistose. The specimens are very similar in mineralogie 

character, though no thin section of the normal type was examined. 

Megascopically A-6 is fine and schistose, and consists of black and 

white bands of feldspar and biotite. A-44 is dark red in color and 

is very compact. Under the microscope the former is schistose, 

hypantomorphic-granular, while the latter is similar but without 

showing schistosity. In both, the minerals are feldspar, less quartz, 

and still less biotite. Zircon and apatite are accessory. The feldspar is chiefly orthoclase, which is now and then intergrown with 

plagioclase in the form of microperthite; a little microcline and a 

little oligoclase or andesine occur. The biotite occurs in shreds and 

patches (subparallel in A-6) and is in many specimens considerably 

altered to iron oxide, so that it is black and opaque. Normally the 

pleochroism of the biotite is a = light green and for = dark green. 

Zircon occurs as short, stout, rounded grains, and apatite occurs

»Tho specimens here described were collected by Mr. Lee and the geologic relations are given from 

his observations. The report on the examination of the thin sections was made in 1906. 

ft References are to original specimen numbers; see list, p. .

49964 Bull. 352 08 6 81
82 RECONNAISSANCE OF PART OF WESTERN ARIZONA.

both in small and thin and in large and stout prisms, the latter being 

sometimes irregular in form. The accessories occur within both the 

quartz and the feldspar.

> Farther to the south, in Williams Canyon, the banding of the 

.underlying rocks becomes much more marked, giving long-drawn-out 

black and white bands (A-49), for which reason the name of "Banded 

Canyon" is applied to the gorge through which Williams River flows. 

Lee describes the rock as apparently continuous with the granitic 

rocks to the north, although the transition was not followed. Megascopically the rock is aphanitic, black and white banded, the black 

bands occasionally showing white phenocrysts and rounded inclusions. 

Under the microscope the texture is markedly schisto'se. The constituents are irregular rounded grains, very variable in size, of hornblende, orthoclase, some plagioclase, and a little quartz. There is 

much chlorite, and a little epidote and titanite. 

EFFUSIVE ROCKS. 

OLDER ANDESITE.

Some time during the Tertiary period, after the Paleozoic and 

Mesozoic sediments had been removed from the area and the underlying granite deeply eroded, began a period of volcanic activity. 

The earliest erupted rocks of which traces now remain were andesites, 

a remnant of which occurs at Black Mesa, north of Boundary Cone 

(A-ll). It here appears to underlie and is cut by dikes of rhyolite 

(A-12). This is the only area where any eruptive rock is definitely 

known between the rhyolite" and the granite. In several places the 

andesite (A-40, A-41) rests directly upon the granite, but no rhyolite 

occurs above it, and consequently the later flow and the intervening 

rocks may have been eroded. The andesite from Black Mesa is, then, 

as described above, beneath the rhyolite and is cut by it; and since 

within the rhyolite flow breccia from various parts of the region 

andesite fragments occur, it is very probable that this rock is in place 

and is older than the rhyolite.

Megascopically this andesite (A-ll) is dark reddish gray in color 

and shows numerous white phenocrysts in a fine aphanitic groundmass. Under the microscope the texture is porphyritic and sempatic. The phenocrysts are fairly regular laths, some of which are 

partially and some completely altered. . The partially altered phenocrysts are plagioclase, which still show indistinctly the original 

twinning, but the extinction angle can not now be determined. They 

have an index of refraction higher than Canada balsam, and are much 

altered to calcite, sericite, and kaolin. Besides these, there are fewer 

chlorite pseudomorphs and still less magnetite. The chlorite pseudomorphs are lath-shaped and are very similar in form and size to
IGNEOUS BOCKS OF WESTERN ARIZONA. 83

the plagioclase laths.- None of the original mineral remains, and there 

is occasionally a center of calcite. Possibly they are pseudomorphs 

after hornblende. The magnetite occurs in irregular and corroded 

grains and is usually surrounded by a rusty rim. By incident light 

the surface appears black and metallic, but with rusty patches, the 

smaller grains sometimes having the entire surface rusty. The 

groundmass is anisotropic and full of alteration products, and consists of xenomorphic laths and patches of feldspar, much altered to 

kaolin, sericite, and chlorite, and of magnetite grains and dust. It 

has the appearance of having originally contained small lath-shaped 

feldspars. Whether there was also originally orthoclase is indeterminable. Kaolin occurs as a secondary product in semiopaque 

patches in the groundmass and in the feldspar phenocrysts.

RHYOLITE SERIES.

Resting upon the andesite at Black Mesa, and in other places 

directly upon the granite,.is a thick series of rhyolites, rhyolite flow 

breccias, and tuffs, which reach a thickness of" 3,000 feet or more. 

They are all clearly older than some of the andesites (107, A-18) and 

older than all of the basalts. In the field the general appearance of 

the rhyolite is white to pink, making a sharp contrast with the underlying granite and the overlying andesites and basalts. Usually the 

flows are massive, often brecciated, and often very coarse agglomeratic, with angular blocks having a maximum diameter of several 

feet. In places these included fragments are rounded and the bedding of the tuffs is horizontal. No attempt was made to separate 

the rhyolite into distinct flows, as might be possible with more detailed 

study. The areas at which the specimens studied were collected 

being in many cases far removed from the others, it is impossible to 

correlate the relative geologic positions.

The rhyolites may be divided into four groups flow breccia, ash, 

normal rhyolite, and spherulitic rhyolite.

In general the megascopic appearance of the rhyolite flow breccia 

is white to pink, with included irregular dark-brown fragments, usually 

small. Under the microscope the appearance of all (101, A-13, A-19, 

A-35) is very similar. The rock consists of a glass full of bubbles, 

often in flow lines and sometimes devitrified. It is full of irregular 

and broken fragments of orthoclase, quartz, sometimes a little biotite, 

microcline, apatite, plagioclase, and hornblende, several or all, and 

usually some iron ore. Some of the specimens are altered and contain, besides iron. oxide, much calcite. Besides the mineral fragments contained in the glass, there are irregular dark and altered 

inclusions of andesite, which clearly indicate that there was a previous eruption of a basic rock. No correlation is possible, however,
84 RECONNAISSANCE OF PART OF WESTERN ARIZONA.

between these fragments and the single specimen obtained from the 

flow below the rhyolite at Black Mesa. There may have been, and 

probably were, volcanic eruptions previous to that of the rhyolite, 

of which now no trace remains, and the fragments in the rhyolite flow 

breccia indicate that the andesite was much more extensive than at 

the present time.

West of Boulder Canyon in Colorado River is a volcanic tuff (A-39). 

It is gray to pink in color, ashlike, gritty, very friable, and fine grained, 

and occurs in horizontal beds. Under the microscope it is tuffaceous 

and is composed chiefly of small angular glass fragments, needle-like 

and in flakes, and contains a few very small and irregular quartz 

grains.

Compact normal rhyolite (117, A-7, A-12, A-43) occurs within 

the rhyolite series, but no attempt was made to find the relationship which may exist between these flows and the sheets of 

breccia, flow breccia, and so on, in which it occurs. Megascopically 

these rocks are white or pink and sometimes banded. Under the 

microscope a glassy flow texture is plainly seen in one of the rocks 

(A-43), while in others (117, A-7),although now devitrifled, the flow 

texture can be clearly made out. In 117 the original flow lines of 

the groundmass show in polarized, light by the fact that there are 

larger and more numerous quartz particles along certain lines, while 

areas between these lines are much finer grained, and very often the 

centers of these areas are almost entirely isotropic. In the specimen 

from. Black Mesa (A-12), from the region where the andesite (A-ll) 

underlying the rhyolite was obtained, no flow texture can now be 

made out. It is completely devitrified and is now an aggregate of 

quartz and feldspar. According to Lee, this rhyolite occurs in dikelike intrusions and in sheets overlying the andesite, a fact which 

clearly proves the older age of the andesite, provided that the intruded

and overlying rocks are both like the specimen (A-12). All of the 

sections are perpatic. In some, fragments of orthoclase, a little 

plagioclase, and some quartz occur, and in others the original phenocrysts are much altered. Magnetite and zircon are accessory, and 

calcite and zeolites secondary minerals. Chlorite, from an original 

femic mineral, occurs in 117.

Two of the rhyolite specimens are spherulitic (A-l, A-8). Megascopically these specimens are pink, spherulitic, and full of large 

irregular cavities, occasionally filled with quartz crystals. Under 

the microscope the rock shows very few phenocrysts of orthoclase, 

plagioclase, and biotite, and rather rare magnetite crystals in a.sphemlitic groundmass. In one specimen (A-8) the entire rock is filled with 

trichites, generally in hairlike bunches. Sometimes margarites occur 

that is, hairlike strings of globules; and in places microlites appear 

in schools. In the specimen from Wickenburg (A-l) there is) in the
IGNEOUS BOCK'S OF WESTERN ARIZONA. 85

groundmass, besides the spherulites, a quartz-orthoclase aggregate in 

finger-like interlocking particles. The rock is rather dark with feritic 

material, and there is considerable kaolin and other alteration products. In the rays of the spherulites there is often a deposit of red 

hematite or limonite, and cubes of what may have been magnetite 

show a slight red edge in transmitted light, as though altered to 

limonite.

YOUNGER ANDESI.TE8.

f Definitely in place in a number of localities above the rhyolite is

j an andesite (107, A-18). This is much more limited in extent than, 

the earlier flow. A number of other andesites which occur in the

' area either rest directly upon the granite (A-40, A-4.1) or are in 

masses isolated from the other eft'usives, so that no relationship is 

seen (112, A-2, A-42); they may belong either to the upper flow, the 

underlying rhyolite having been eroded, or to the earlier flow. In 

the field all of the andesites are of a dark-red to brown color, are often 

vesicular, and are often very hard to distinguish from the overlying

«- olivine basalts.

The two specimens (107, A-18) from above the rhyolite are dark 

reddish black in color and are vesicular, with, more phenocrysts in A18 than in 107. Under the microscope the two rocks are very similar 

in appearance. Both of them are porphyritic-intersertal in texture 

and contain more phenocrysts than groundmass. The phenocrysts

. occur in two generations and consist of plagioclase (andesine to labradorite), augite, and magnetite. The larger plagioclase crystals

^ occur as irregular fragments, often zonal, while the smaller occur in 

perfect laths. There is much less augite than plagioclase. This also 

occurs in two generations, and in each case is less in amount than the 

corresponding generation of plagioclase. Two generations of magnetite, less in amount than the augite, occur in quadratic and irregular crystals and grains. Of these the larger crystals are less in amount 

and the grains are smaller than the second generation of augite, and 

the small crystals are very small and are scattered through the groundmass in isometric crystals. They occasionally occur in the augite,

 but very rarely in the feldspar. The groundmass in both specimens 

is isotropic and consists of brown glass full of magnetite so much 

in A-18 that it is nearly opaque.

Specimens A-40 and A-41, from sheets in the walls of Black Canyon,

»- are augite andesite; possibly the latter at one time contained olivine; 

if so, it was an olivine basalt. Megascopically they are medium dark 

red-brown in color, with more or less black and white phenocrysts in

. an aphanitic groundmass. Under the microscope they are porphyritic and sempatic. The phenocrysts of 40 consist of broad, irregular 

laths, and the groundmass is apparently a devitrified glass, full of
86 RECONNAISSANCE OP PART OP WESTERN ARIZONA.

dust and grains of magnetite and hematite. Specimen 41 lias phenocrysts of plagioclase, somewhat greater in amount than augite and/- 

much greater than some red-brown pseudomorphs which may be 

altered biotite or olivine. The groundmass in this specimen is in 

laths and irregular patches, much of which is definitely plagioclase. 

Besides the feldspar, much black and red iron oxide and shreds of 

augite and dark altered biotite (?) occur.

A-42 is a biotite-augite andesite from a sheet forming Eagle Hock, 

near Little Kound Island, and is similar in character to the two preceding. The phenocrysts, less in amount than the groundmass, are, 

in the order of their importance, plagioclase, biotite, diopside, and 

magnetite. The plagioclase is andesine to labradorite. The biotite 

has a peculiar deep red-brown color, is pleochroic with l)=brown.ish 

red and a=greenish yellow, and has much the appearance of basaltic 

hornblende. It has, however, parallel extinction, gives a uniaxial interference figure, shows parallel cleavage in laths, has the "bird's-eye 

maple" surface, and is optically negative. It always has a dark rim 

of magnetite. The pyroxene is pale green in color, is nonpleochroic, 

has an extinction of about 40°, and has good cleavage parallel in 

laths and at right angles in basal sections. It is diopside. Both the 

plagioclase and the pyroxene are much altered to calcite. The ground 

mass is yellowish to red, cloudy, and apparently partially devitrified 

glass full of red ore dust. Most of the anisotropic part of the groundmass is spherulitic or contains innumerable microlites.

South of Seligman there is a hypersthene andesite (113). This is 

from the lower of two flows, the upper of which is darker and maybe 

basalt, though no specimen was examined. Megascopically 113 is 

a dark-gray rock with white patches and occasional calcite fillings in 

cavities. Microscopically the texture is porphyritic arid dopatic. The 

phenocrysts are either thin or broad laths, and the groundmass is 

hypautomorphic. The phenocrysts, in the order of their abundance, 

are plagioclase, augite, and hypersthene. The feldspar occurs in both 

large and small laths. The stout crystals are not twinned and are 

always zonal; the narrow crystals are usually twinned and give an 

extinction between 20° and 25°, or that of andesine. In the zonal 

feldspars the index of refraction at the center is higher than at the 

rims; the interference figures are positive, and show a comparatively 

small value for 2E. This excludes all the feldspars but andesine and 

labradorite. Since the rims have a lower index but are still positive 

in character, it shows that the feldspar is either labradorite or andesine 

or both, and that the interior is more basic than the exterior. The 

femic minerals consist of very irregular grains of a greenish pyroxene 

with a high extinction angle augite; and another pyroxene occurring in elongated prisms with longitudinal cleavage, having parallel 

extinction, showing high interference colors, optically negative, and
IGNEOUS ROCKS OF WESTERN ARIZONA. 87

slightly pleochroic in pink and green tones hypersthene. Magnetite 

occurs in grains which, in size, grade into the groundmass. There is 

no definite line, and it is in such irregular grains that it may be included 

with either the phenocrysts or the groundmass. Exclusive of the 

femic minerals, the groundmass is made up of xenomorphic areas and 

laths of feldspar which are probably of the same kind as the large 

phenocrysts. The xenomorphic feldspar has an index of refraction 

greater than Canada balsam and is consequently plagioclase, but the 

areas are so small that the kind is indeterminable. Besides the feld- 

.spar there is an isotropic substance which occurs in very small anhedrons and which may be glass or a zeolite. The groundmass is full 

of magnetite dust and there is an alteration product in the cleavage 

cracks of some of the feldspars which is anisotropic and has an index 

of refraction less than Canada balsam. It is a zeolite.

Twenty-five miles west of Congress Junction there occurs a coarse 

breccia formed of large angular blocks cemented with red material. 

Megascopically the specimen (A.-2) has a red compact groundmass, 

and there are phenocrysts of hornblende forming about one-eighth 

of the mass. Microscopically the texture is porphyritic and perpatic. 

The phenocrysts are hornblende, much less plagioclase, and still less 

biotite. The hornblende is very peculiar in several ways. It has a 

very low extinction angle, generally appearing as parallel, the largest 

found being only 3f° that is, c: £ is circa 4°. The pleochroism is 

also peculiar. For a it .is a greenish, yellow, while for £ it is a deep 

red-brown. Absorption C>a. The elongation is parallel to £, and 

therefore it is positive, while the optical character of the mineral is 

negative. Surrounding the mineral there is always a dark rim of 

iron oxide. This is usually black, but occasionally it shows a red 

tone. The cleavage is good, parallel to d; in lath-shaped sections, and 

in basal sections the usual amphibole cleavage. The mineral is basaltic hornblende. The feldspar is generally zonal and is positive in 

character. It is between andesine and labradorite. Actually the 

amount of plagioclase that occurs is much less than the amount of 

hornblende, but the phenocrysts of feldspar have either weathered 

out .or been ground out in preparing the thin section. Apparently 

they were originally much more numerous and both longer and broader 

than the hornblende. Biotite occurs in a very few long, thin flakes. 

It has dark rims, and magnetite is included along the cleavage lines. 

Pleochroism is brownish to greenish. Magnetite occurs in irregular 

grains. The groundmass consists chiefly of laths of plagioclase, which 

have an extinction angle of 30° and are consequently labradorite. 

Between the feldspar laths there is a much iron-stained substance 

which is probably glass. Iron oxide occurs in the form of very fine 

dust and in patches, producing the red color of the rock.
88 RECONNAISSANCE OF PART OF WESTERN ARIZONA.

OLIVINE BASALTS.

Resting upon the andesite, upon the rhyolite, or even upon the 

granite, and also upon and within Quaternary gravels, depending upon 

the amount of erosion that has taken place, is a series of olivine 

basalts the youngest lava in the region. There are at least three 

flows of this, but it is impossible, from the amount of field work 

done, to correlate the different sheets in different parts of the area. 

Five or six varieties can be distinguished under the microscope, but, 

they may be but different phases of the same rock, a greater or less 

development of olivine or a coarser or finer groundmass forming 

the various types. This difference in appearance may be seen even 

in two sections (as 110, 111) which have been collected near together from undoubtedly the same flow and which show different 

characters. Five types may be distinguished, according to the fineness of the groundmass: (A) 110, 111, 3, 45; (B) 15, 16, 24, 25, 27; 

(C) 37, 46; (D) 22, 23; (E) 30, 34.

Occasionally the field relation can be seen; thus, 24 is from a sheet 

overlying 25; 15 is from a sheet intruded into the rhyolite and lifting 

it; and 16 is from a sheet above the rhyolite.

In the field the general appearance of the basalt is black or very 

dark red. In general it is darker in color than the underlying andesite and is often vesicular and ropy. Where it rests upon the rhyolite 

it forms sharp cliffs. In many places it forms flows in erosion valleys, and though actually lower in position, is higher geologically.

Megascopically the hand specimens are compact and vary in color 

from black through dark gray to dark brownish red. Occasionally 

there is a somewhat banded arrangement that is, alternating bands 

of a lighter color. Under the microscope the texture of all the specimens is porphyritic, with a groundmass generally trachytic and with 

the small plagioclase laths in subparallel position. In general the 

phenocrysts of the rock are olivine, or, when other minerals occur, 

they are greatly in the minority. In four specimens, however (22, 

23, 45, 46), the phenocrysts are chiefly plagioclase.

In specimens 22 and A-23 the plagioclase phenocrysts are greatly 

in excess of the olivine, and the latter are much in excess of the 

augite. The groundmass is much coarser than A-45 and consists 

of plagioclase laths and areas, less augite grains, and still less magnetite. The feldspar is labradorite. Olivine is very much altered to a 

red-brown mineral which may be iddingsite or an iron-stained serpentine. Some of the olivine is fresh and shows simply an altered 

rim or altered center.

A-45 is p'erpatic, has a much finer groundmass than either A-22 

or A-23, and does not contain prominent augite grains in the groundmass. The constituents, in the order of their abundance, are plagio-
IGNEOUS BOCKS OF WESTERN ARIZONA. 89

clase, augite, olivine, and magnetite. The feldspar is labradorite or 

andesine. The olivine occurs in doubly terminated crystals, only 

slightly altered.

A-46 is very similar to A-23, except that the difference between 

the size of the grains in the groundmass and the phenocrysts is not 

so great.

Specimens 110, 111, and A-3 are similar to A-45, in having a very 

fine groundmass. The phenocrysts of 110 and 111 are augite and 

biotite in about equal amounts, and less of a completely altered redbrown mineral which may have been olivine. The biotite and augite 

are usually altered in part also, and are surrounded by black rims. 

The groundmass consists of lime-soda feldspar laths in subparallel 

. position in swirling eddies a trachytic texture. There are also a few 

small irregular patches in the groundmass which have an index of 

refraction less than Canada balsam and are faintly anisotropic. 

They may be analcite, but are too small to determine. Calcite 

occurs as a secondary product, and magnetite occurs in a few large 

crystals as well as in small grains in the groundmass.

. In A-3 there are more augite phenocrysts than olivine. The latter 

is altered, completely or in cracks, to a red-brown mineral, which 

has an index of refraction much less than that of the olivine and is 

fibrous. It appears to be iron-stained serpentine. Magnetite 

occurs within the olivine in' rather large grains and crystals. The 

groundmass consists of laths of labradorite in broad flow lines swirling 

around the olivine phenocrysts. Almost invariably they are twinned 

according to the albite law, and show an extinction angle in the 

neighborhood of 30°. Between the feldspar laths is much augite, 

pale green in color, and occurring in irregular grains, never in wellformed crystals or laths. Somewhat less in amount is magnetite, 

which occurs in cubical and irregular sections. Less in amount than 

the magnetite and, like it and the augite, occurring in irregular 

grains between the feldspar laths, is a reddish-brown mineral which 

has an index of refraction apparently greater than the augite. The 

grains are small and irregular, so that the determination is impossible. 

It appears to be partially altered olivine.

Somewhat coarser in texture under the microscope than the above 

are A-15, A-16, A-24, A-25, A-27, A-37. Of these, A-15 and A-16 

have phenocrysts of olivine, augite, and plagioclase, with hornblende 

and biotite also in A-16. The olivine. phenocrysts are generally 

entirely altered to a brownish-red serpentine and are usually ground 

out in the centers in preparing the section. The grbuhdmass of A-l 5 

is a dark glass full of small laths of plagioclase, laths of augite^ and 

grains of red iron oxide, while A-16 has a groundmass of dark glass 

full of innumerable small feldspar laths and microlites and magnetite 

dust.
90 RECONNAISSANCE OF PART OP WESTERN ARIZONA.

A-24, A-25, A-27, and A-37 are very similar in appearance. 

The texture of all of them is porphyritic, with phenocrysts of olivine 

and a groundmass made up of laths of feldspar and grains of augite 

and magnetite and glass full of magnetite dust. The amount of 

glass is smaU and fills spaces between the plagioclases, but these 

spaces are very few and hardly show in the thickness of the section. 

The olivine phenocrysts are rather fresh, being generally altered only 

around the rims. Secondary calcite is common. . A-37 has more plagioclase than A-24 and the olivine is entirety 

altered to a dirty brownish-black substance;

A-30 and A-34 are porphyritic, with irregular rounded to angular 

crystals of olivine which are perfectly fresh. Some magnetite ma}r 

be classed with the phenocrysts. The groundmass consists of long, 

narrow laths of labradorite with extinction angles of from 32° to 35°, 

and a less amount of a purplish, very slightly pleochroic augite, 

which fills the interspaces. The augite is not in typical ophitic form, 

but in irregular laths which fill the interstices. Generally it is very 

fresh, although there are patches of serpentine in the groundmass, 

some of which is definitely derived from olivine. Within the augite 

there is a great deal of magnetite in strings and in skeleton crystals, 

in beautiful branching forms.

DIKE ROCKS. 

OLIVINE DIABASE.

Cutting the rhyolite at the eastern edge of Black Mesa, in Gold 

Roads Pass at Mud Spring, is a large dike, some 25 feet in thickness, 

of olivine diabase (A-14), apparently connected with a dark sheet 

which overlies the rhyolite. Megascopically the rock is dark in 

color and is rather coarsely 'granular. Under the microscope it has 

a typical ophitic texture and there is more feldspar than augite. The 

feldspar occurs in twinned laths with a maximum extinction angle 

of 31°, and is labradorite. It is very fresh, although occasionally it 

contains serpentine in cleavage cracks. , Fresh augite in less amount 

than the plagioclase fills the interspaces between the feldspar laths. 

It is pale purple in color, and is nonpleochroic or very slightly pleochroic. It contains a small amount of iron oxide in extremely fine 

particles. Olivine, less in amount than the augite, occurs in irregular rounded grains, mostly small, though some are large. Some of 

the olivine is altered to serpentine, chlorite, and red iron oxide 

around the edges and in cracks. Magnetite occurs in still less amount 

and in irregular grains.

RHYOLITE PORPHYRY.

At the base of Boundary Cone is a plug, or dike from a plug, of 

rhyolite porphyry (A-10). Megascopically it is a pink, fine-grained
IGNEOUS ROCKS OF WESTERN ARIZONA. _ 91

rock, with quartz and feldspar phenociysts. Under the microscope 

the texture is.porphyritic and dopatic. The phenociysts are large, 

occasionally somewhat corroded, and the groundmass is xenomorphicholocrystalline. The phenocrysts are orthoclase, greater in amount 

than quartz, and much greater than acid plagioclase. The plagioclase occurs in but few crystals; it has, in part at least, an index of 

refraction less than Canada balsam, and is probably all albite. The 

groundmass is a quartz-feldspar aggregate with much hematite. 

Secondary kaolin and sericite are derived from the feldspar, and the 

red iron oxide perhaps from magnetite.

ROCK SAMPLES FROM NORTHWESTERN ARIZONA.

Following is a list of rock samples collected in northwestern 

Arizona with the original specimen numbers:

A-fi. Granitic gneiss from south end of Hualpai Mountains.

A-J.O. Granite porphyry from base of Boundary Cone west of Black Mesa.

A-44. Biotite granite from mouth of Williams River.

A-49. Granite gneiss from Williams Canyon.

101. Rhyolite flow breccia from Lost Basin, about 5 miles south of Colorado River, 

in a depression of older crystalline rock.

A-35. Rhyolite breccia from Temple Bar.

A-7. Rhyolite from southern end of Black Mesa, at base of cliffs.

A-39. Rhyolitic tuff from Colorado River west of Boulder Canyon.

A-12. Rhyolite from Black Mesa, at Gold Roads.

A-13. Rhyolitic tuff from Black Mesa, in pass east of Orolcl Roads.

A-19. Rhyolitic tuff from Black Mesa, at summit of Union Pass.

A-43. Rhyolitic tuff from bluffs of Colorado River in Chemehuevis Valley.

A-2. Hornblende andesite from southern end of Aquarius Mountains, a few miles 

north of Date Creek.

A-ll. Andesite from Black Mesa, north of Boundary Cone.

A-40. Andesite from, north end of Black Canyon.

A-41. Andesite from south end of Black Canyon.

A-42. Andesite from Eagle Rock, near Little Round Island.

107. Andesite from coyote holes northwest of Kingman, at western edge of mesa. : A-18. Andesite from a sheet above the rhyolite 2 miles northwest of Kingman.

110, 111. Basalt from a flow sheet 300 feet thick resting on top of 4.00 feet of varicolored 

ash and breccia at mouth of White Cliff Creek.

112. Andesite resting on granite at top of Cottonwood Cliffs near mouth of Cottonwood Creek, 1,200 feet above Nos. 110 and 111.

A-3. Olivine basalt from a sheet in the detrital beds of Santa Maria Canyon, near 

mouth of Big Sandy Wash.

A-15. Basalt intruded into the rhyolite 1 mile west of Kingman.

A-lfi. Basalt from a flow sheet above the rhyolite 1 mile west of Kingman.

A-27. Olivine basalt from a sheet above the andesite near Kingman.

A-30. Olivine basalt from a columnar sheet resting on the Temple Bar conglomerate 

north of Colorado River in Grand Wash.

A-34. Olivine basalt from a flow sheet within the Temple Bar conglomerate near 

Greggs Ferry.
92 RECONNAISSANCE OF PART OF WESTERN ARIZONA.

A-14. Olivine diabase from the eastern edge of Blaf.k Afesa, at meadow spring in Gold

Roads Pass; dike cutting the rhyolite.

A-22. Olivine basalt from Mud Spring at eastern edge of Black Mesa. 

A-23. Olivine basalt from north end of Cerbat Mountains. 

A-24. Olivine basalt from a sheet resting upon granite east of Cerbat Mountains. 

A-25. Olivine basalt from a sheet resting above A-24. 

A-45. Basalt from a sheet 800 feet thick covering the Temple Bar conglomerate in

Williams Canyon. 

A-46. Olivine basalt near Planet, in Williams Canyon.
INDEX.

A.

Andesite, older, eruption of................. 58

occurrence and character of.............. 82-83

Andesite, younger, eruption of ............. 59

occurrence and character of............. 85-87

Aquarius Cliffs, description of .............. 13,20

location of.............................. 13-20

section of, plate showing................ 24

Aquarius Moun tains, description of......... 22

location of.............................. 13,22

rocks of................................. 22

view of.................................. 22

Arizona, geographic provinces of............ 11-12

western part of, map of................. 9

Arnold, Ralph, on Pacific coast correlation.. 71-72

Artillery Mountains, description of........... 22

location of.............................. 13,22

rocks of................................. 22-23

Artillery Peak, section of, plate showing..... 24

Ash, rhyolitic, view of....................... 22

Aubrey Canyon, description of.............. 44-45

rocks in................................. 45

.Aubrey Hills, description of................. 13,25

location of.............................. 13,25

rocks of................................. 25

B.

Basalt Qows, description of.................. 38

occurrence of...................... 20, 61-62,03

Base-leveling, period of...................... 56

Big Bend, description of.................... 43

Big Sandy Valley, description of............ 50,64

rocks of................................. 51

sections of, figures showing.............. 24,51

structure of............................. 51-52

wells in................................. 79-80

Big Sandy Wash, flow of.................... 77

Black Canyon, description of................ 37

entrance to, view of..................... 34

erosion in............................... 65

rocks in................................. 26,37

section in, figure showing............... 37

Black Mesa, description of.................. 26-27

erosional forms at, view of............... 26

location of.............................. 13,26

rocks of................................. 27

section of, plate showing................ 24

Black Mountain Range, description of....... 13

location of.............................. 13

Black Mountains, description of............. 25-26

location of ............................... 13,25

rocks of................................. 26

Page. 

Blake, W. P., on iron ore of region.......... 11

Bonneville, Lake, correlation of, with western Arizona ..................... 68-71

Boulder Canyon, description of.............. 36-37

erosion in............................... 65

rocks in................................. 26,36

section of, figure showing................ 35

Boundary Cone, elevation of................ 27

Boutwell, J. W., on Lake Bonneville beds... OS 

Buckskin Mountains, description of...... 14,28-29

location of.............................. 14,28

rocks of................................. 29

Bulls Head rock, channels at................ 39-41

views at................................. 22,40

C.

71

Cacopah dam si te, channels at...............

Cactus Plains, description of................

section of, plate showing..... ~...........

underground water in...................

California, southern, correlation' of, with 

western Arizona................

Cambrian rocks, occurrence and character of. 15,21

Canyon cutting, first period of. description of. 62-63 

second period of, description of.......... 65

third period of, description of........... 66

Carboniferous rocks, description of.......... 15-16

fossils in................................ 15-16

Cedar, mining at........................... 25

Cerbat Mountains, description of............ 13,23

location of............................... 13,23

rocks of................................. 23-24

section of, plate showing................. 24

structure of.............................. 24

uplift of................................. 61

Chamberlin,. T. C., on river erosion.......... 66-67

Chemehuevis gravel, deposition of........... 65-66

occurrence and character of.. 18,41-42,43-44,46 

view of.................................. 22

Chemehuevis VaUey, description of........ .. 43-44

sections in, figures showing.............. 44

Cherums Peak, elevation of.................. 23

Chocolate Canyon, channels at.............. 49

map and section of...................... 48

Chocolate Mountains, canyon in............. 47-48

canyon in, rocks in...................... 48

Colorado Plateau, section of, plate showing.. 24

Colorado River, channel of, filling in......... 75-76

dams on................................. 75-76

diversion of.............................. 64-65

effect of uplift on........................ 62

93
94 INDEX.

Page. 

Colorado River, flow of..................... 74

history of. See Historical geology.

irrigable lands on........................ 74-75

rapids in................................. 30

view of.................................. 40

Colorado Valley, description of.. 29-30,34-37,37-48 

gravel in, view of........................ 40

relation of, to Detrital-Sacramento Valley 61 

sections across, gflures showing.......... 22

tributary valleys of, description of.... 30-34,37

Cooley, , on river erosion................ 66

Correlations, data on ........................ 68-74

Cottonwood Cliffs, description of............ 13,20

location of............................ 13,19-20

rocks of.................................. 20

Cottonwood Valley, description of........... 37-38

rocks in................................. 26,38

Criistal movements, period of................ 58-59

Cunningham Pass, rocks in.................. 28

D.

Darton, N. H., work in charge of............ 9

Date Creek, course of........................ 22

geology near............................. 55

Davis, W. M., on Plateau region............ 72

Deluge Wash, detritus at mouth of, view of-. 22 

gravels in................................ 51

section at, figure showing................. 51

Denudation, period of....................... 57

Desert region, location and character of...... 11-12

Detrital-Sacramento Valley, description of.. 52-53,

CO-01 

filling in.............................. 53,03-64

formation of.......................... 45,60-61

relation of, to Colorado Valley........... 61

sections of, plate showing................ 24

view in.................................. 52

Diastrophism, progress of................. 10,58-59

Dike rocks, occurrence and character of...... 90-91

Dome Rock Mountains, location of.......... 29

Drake, well at............................... 78,80

well at, record of........................ 79

Eagle Rock, channels near...................

channels near, figure showing...........

Effusive rocks, occurrence and character of.. 

Erosion, forms of, view of....................

period of................................

Evaporation, data on........................

39 

38

82-90 

24 

58 

74

F.

Flood plains, formation of ............ .'...... 66-67

Flow breccia, description of .................. 83-84

Formations, description of ................... 14-18

distribution of ........................... 10

Fortification Hill, rocks of. .................. 37

Fossils, occurrence and character of. ......... 15, 16

Geography, description of ................... 11-14

Geologic liistory, outline of .................. 56-74

re'sume' of ............................... 67

Geologic sections, plate showing. ............ 24

Geology, description of ...................... 14-18

Page.

Gilbert, G. K., on erosion...........-..._.... 57

on Lake Bonneville beds................ 68-71

on Grand Wash fault.................... 31

onRedwalllimestone.................... 16

Gilbert and Marvine, on region.............. 11

Girty, G. H., fossils determined by.......... 16,17

Gold Basin, well at.......................... 78

Gold Roads, rocks at........................ 26

Grand Canyon, cutting of................... 62

description of........................... 30

mouth of, section of, figure showing...... 31

view at.............................. 30

rocks of................................. 30

section of, plate showing................ 24

travertine in............................ 30

Grand Wash. Cliffs, description of........ 13,19,31

location of............................... 13,18

rocks of......;........................... 19

Grand Wash, fault, description of......... 31-32,50

 formation of............................. 59

Granite Wash Hills, description of.......... 28

location of............................... 28

 Grand Wash Trough, canyon of, wall of, view

of............................... 30

description of........................... 30-33

formation of............................. 59

geologic history in....................... 33

rocks in.............................. 31,32-33

sections of, plate showing...;........... 24

Granite, occurrence and character of........ 14-15,

19-27,51,81-82

Great Colorado Valley, description of........ 45,47

map of............................... i.. 46

rocks of................................. 47

silt in.... ............................... 47

Greggs breccia, deposition of..............'.. 59-60

description of........................... 17,32

Greggs Ferry, section near, figure showing... 34

Gypsum, occurrence of...................... 36

H.

Hackberry, well at.......................... 78,80

Hamlin, Homer, on Cocopah dam site....... 48

on Colorado River irrigation............. 75

Harcuvar Mountains, description of......... 14,28

location of............................... 14,28

rocks of................................. 28

section of, plate showing................ 24

Harquahala Mountains, description of....... 14,28

location of............................... 14,28

rocks of................................. 28

section of, plate showing................ 24

Harrisburg, rocks near...................... 28

well near................................ 80

Haviland, well at........................... 79,80

well at, record of........................ 79

Hematite, occurrence of..................... 29

Highlands, geographic and geologic details of. 18-29

History, geologic, outline of................. 56-74

re'sume of............................... 67

Hualpai Mountains, description of........... 13,24

formation of............................. 61

location of............................... 13,24

rocks of................................. 25

sections of, figures showing.............. 24

structure of............................. 25

view in.................................* 52
INDEX. 95

Page.

Hualpai Peak, elevation of.................. 24

Hualpai Valley, description of............... 49-50

filling in................................ 64

formation of ................. ----- ----- 61

sections of, plate showing.......... .... 24

structure of .................---.----- - 50

underground water in................... 77

Hualpai Wash, description of............... 33

rocks in................................. 33-34

section near, figure showing............. 34

Huntington, E., and Goldthwaite, J. W., on

Grand Wash fault............... 31-32

. on Toquerville region................... 72-73

I.

Iceberg Canyon, section of, figure showing... 31 

Igneous rocks, description of................ SI-91

occurrence and character of........ 20,23-29,35

Investigation, scope of....................... 9-10

K.

Kinginan; rhyolitic ash at, view of........... 22

wells at.............................. '.... 78,80

Las Vegas W ash, description of.............. 37

rocks of.................................. 37

section near, figure showing.............. 37

Lighthouse Rock, channels at................. 48

M.

McCarii, H. L., on minerals of region........ 11

McMullan Valley, description of............. 55

section of, plate showing:................ 24

underground water in.................... 77

wells in.................................. 80

Map of western Arizona...................... 9

Marcou, Jules, on region...................... 10-11

Mesozoic history, outline of................... 57

Mohave Canyon, description of............... 42-43

Mohave Mountains, description of........... 27-28

location of............................... 13,27

rocks of............................... 28,42-43

Mohave Peak, section of, plate showing....... 24

Mohave peneplain, extent of................. 73-74

Mohave Valley, description of................ 41

rocks of.................................. 41-42

section of, figure showing................. 42

Mountain region, location and character of.... 11-14

Mountains, description of.................... 12-14

See also Highlands. 

Mount Perkins, elevation of.................. 26

Mount Wilson, elevation of................... 25

Murphy, E. C., on precipitation ............. 74

Music Mountain, section of, plate showing.... 24

N.

Needles, description of................. 27-28,42-43

location of............................... 27,42

rainfall at................................ 74

rocks of.................................. 28,42

section of, figures showing................ 24,42

Neels, Utah, well at, section of................ 69-70

Nelson, fossils from.......................... 16

well at................................... 78,80

record of............................. 78

Newbcrry, J. S., on geology of region.........: 11'

0.

Olivine basalts, occurrence and character of.. 88-90 

Olivine diabase, occurrence and character of . 90

P.

Pacific coast, comparison of, with western

Arizona......................... 71-72

Paleozoic history, outline of.................. 57

Palomas Mountains, location of.............. 29

Peach Springs, well at........................ 78,80

well at, record of.......................... 78

Peacock Mountains, rocks of................. 25

Plains, description of......................... 13

Planet, iron ore near......................... 11

Plateau region, comparison of with western

Arizona.......................... 72-74

location and character of................. 11-12

uplift of................................. 61-62

Powell, J. W., on region...................... 11

Pratt, J. H., on gold deposits................. 11

Pro-Cambrian history, outline of...........'.. 56

Pre-Cambrian rocks, occurrence and character

Of........'............-. .^4-15,23,81-82

See also Granite. 

Precipitation, records of..................... 74

Posas Plain, description of................... 55

Pyramid Canyon, description of.............. 30-41

map and section of, plate showing........ 38

reclamation work at...................... 39-40

rocks i n.................................. 26,39

sections at, figures showing............... 40,42

Quaternary history, outline of .............. 62-07

Quaternary rocks, occurrence and character

of............................. 17-18,23

R.

llainfall, records of.......................... 74

Ranegras Plain, description of............... 55

Rapids, occurrence and character of......... 30

Red Lake, location and character of......... 49

Redwall limestone, character and distribution of...................15-16,19,21,57

fossils from.............................. 15,16

Rhyolite, eruption of........................ 59

occurrence and character of.............. 83-85

Rhyolite porphyry, occurrence and character

of................................ 90-91

Rhyolitic ash, view of....................... 22

Rivers, diversion of.......................... 64-65

Rocks. See Formations.

Rock samples, list of......................... 91-92

Round Island, rocks near.................... 39

section near, figure showing............ 37

S. . 

Sacramento Valley, view in.................. 52

See also Detrital-Sacramento. 

Sacramento Wash, gravels in, view of...... 40

Salt, occurrence of........................... 36

Salt River, diversion of...................... 64

Santa Maria Canyon, description of.......... 22,53

Scope of work, statement of.................. 9-10

Scour, depth of........................... 66-67,76

Signal Canyon, description of................ 52

rocks in................................. 22

view in.................................. 22
96 INDEX.

Page.

Silliman, Benjamin, jr., on geology of region.. 11 

Silt, deposition of............................ 46

Spherulitic rhyolite, occurrence and character

of................................ 84-85

Spurr, J. E., on Nevada geology.............. 58

Strainer, definition of........................ 30

Streams, description of...................... 74

Surface waters, description of................ 74-77

T.

Temple Bar, conglomerate at, views of...... 16,34

description of............................ 35

rocks at................................. 35-36

section at, figures showing............... 24,35

Temple Bar conglomerate, basalt in...... 18,33,35

correlation of............................ 64

deposition of............................. 63-64

occurrence and character of............. 17-18,

33,35-36,53,56 

views of................................. 16,34

Tertiary history, outline of............... 57-62,67

Tertiary rocks, occurrence and character of.. 16-17,

21,22,23 

Totito formation, character and distribution

of.....................'........ 15,19,57

Topography, description of.................. 12-14

Travertine, occurrence and character of...... 30,34

Trout Creek, gravels in...................... 51

section at, figure showing................ 51

Truxton Canyon, fossils from................ 15,16

Truxton Plateau, description of............. 21

location of............................... 21

rocks of.................................. 21

section of, plate showing................. 24

Tuff, occurrence and character of............ S4

U.

Underground waters, description of.......... 78-80

indications of............................ 77

Page. 

Union Pass, erosional forms at, view of...... 26

Uplift, occurrence and effects of.............. 01-62

V.

Valleys, description of....................... 14

geographic and geologic details of........ 29-56

Virgin Canyon, description of................ 34

rocks of................................. 23,34

section of, figure showing................ 34

Virgin Valley, description of................ 36

section of, figure showing................ 35

Volcanism, occurrence of.................... 63

W.

Water development, future of............... 9-10

Water supplies, discussion of............ '.... 74-80

Wells, data on............................... 78-80

temperatures in...................'...... 80

White Cliff Canyon, rocks of................ 20

section of, figure showing................ 20

White Hills, description of.................. 13,23

location of............................... 13,23

rocks of.........................J...... 23

Williams Canyon, basalt-capped gravels in,

view of.......................... 26

description of............................ 54

rocks of.............................25,29,54-55

section of................................ 54

Williams River, flow of...................... 77

Williams Valley, description of.............. 53-54

rocks in................................. 54-55

Y.

Yampai, fossils from......................... 15

Yampai Cliffs, description of..............13,20-21

location of............................... 13,20

rocks of.................................. 21

section of, plate showing................. 24

Yucca, wells at.............................. 79,80

wells at, record of....................... 79

Yuma, evaporation at....................... 74

flow at.................................. 74

0