Uranium Deposits at

Base of the Shinarump

Conglomerate

Monument Valley

Arizona

GEOLOGICAL SURVEY BULLETIN 1030-C

This report concerns work done on behalf 

of the U. S. Atomic Energy Commission 

and is published with the permission of 

the Commission

Uranium Deposits at 

Base of the Shinarump 

Conglomerate 

Monument Valley 

Arizona

By I. J. WITKIND

CONTRIBUTIONS TO ^THE GEOLOGY OF URANIUM

GEOLOGICAL SURVEY BULLETIN 1030-C

This report concerns work done on behalf 

of the U. S. Atomic Energy Commission 

and is published with the permission of 

the Commission

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1956
UNITED STATES DEPARTMENT OF THE INTERIOR 

Fred A. Seaton, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U. S. Government Printing Office 

Washington 25, D. C. - Price 65 cents (paper cover)
CONTENTS

 Page

Abstract_______________________________________ __ 99

Introduction and acknowledgments __________________________________ 99

General geology __________ ______ ___________ _____________ 100

Shinarump conglomerate _ _. _____________________ 102

Channels_______________ _______________ _________ _____ _____ __ 103

Appearance.. ________ ___ __________ ______________ ________ 103

Classification. _______ ______________ ____ _ ___ ______________ 104

Trends.______-._ ___ _______ __ 106

Widths_________-__._ _________ _ ___ ____. _____ _ __ ______ 113

Floors_____________________________ _._ __ __ __ ____________ 113

Sediments-___ ______ _ __ __________ _____ _ _____ _ _______ 113

Swales associated with channels_ _ _____ _ _ __ ______________ 115

Origin._______ ____________ __________________________________ 116

Localization of uranium ore in channels_ _ _ _____ __________________ 117

Rods________________ ___________________________________ ____ 119

Summary__________ _____________________ _____ _________ _ _ _. 129

Literature cited. _________ ______________________________________ __ 130

ILLUSTRATIONS

[Plates 5, 6 in pocket] 

PLATE 5. Geologic maps and cross sections of the Monument No. 2 area,

Apache County, Ariz. 

6. Geologic map showing swale in the Monument No. 2 area,

Apache County, Ariz.

FIGURT. 12. Index map of part of the Monument Valley area in the Navajo Page 

Indian Reservation, Apache and Navajo Counties, Ariz___ 100

13. Schematic block diagrams showing modes of outcrop of

channels in the Monument Valley area, Arizona__________ 105

14. Geologic map and cross section of Monument No. 1 channel,

Navajo County___-_-___-__---_____-___---- _________ 106

15. View of Mitchell Mesa channel 1, Navajo County.________. 107

16. View of Alfred Miles channel 1, Navajo County. _________ __ 108

17. View of Monument No. 2 channel, Apache County. ________ 109

IS. Geologic and resistivity interpretations of channels in the

Koley Black area, Navajo County_ _________ ___________ 110

19. Map showing distribution of channels in the Monument

Valley area, A1 izona___________________ _________________ 111

20. Diagrams shoeing channel trends in the Monument Valley

area, Arizona and ITt ah _________________________________ 112

21. Illustrations of simple and complex rods in Monument No. 2

mine, Apache County.- ___ _________________--_----_- 120

22. View of large complex rod in Monument No. 2 mine, Apache

County_~__________._._. __--_______. ________________ 121

23. Oblique view of complex rod in .Monument No. 2 mine,

Apache County.____________________.________-_---_-_ 122

24. Longitudinal view of complex rod in Monument No. 2 mine,

Apache County.______ _____________ ________________ 123

25. Photomicrographs showing orientation of fractures- _________ 124

26. Photomicrograph showing irregular fractures of channel sediments... __________ __ _____ ___ __________________ __ 125

27. Diagrams comparing orientation of fractures, rods, and 

silicified wood fragments in Monument No. 2 mine, Apache 

County.._..-._ -____ _____________ ___ ____________ 127

in

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

URANIUM DEPOSITS AT BASE OF THE SHINARUMP 

CONGLOMERATE, MONUMENT VALLEY, ARIZONA

By I. J. TViTKixn

ABSTRACT

Exposed sedimentary rocks on the Navajo Indian Reservation in Apache and 

Navajo Counties, northeastern Arizona, range from the Halgaito tongue of the 

Cutler formation (Permian) to the Salt Wash member of the Morrison formation (Jurassic). The dominant structural element of the area is the Monument 

upwarp, a large asymmetrical anticline whose northern end is near the junction 

of the Green and Colorado Rivers in Utah and whose southern end disappears 

near Kayenta, Ariz. Asymmetrical anticlines with steeply dipping east flanks 

and gently dipping west, flanks are superimposed on the upwarp. These subsidiary structures trend northward.

The uranium-ore bodies are localized in conglomeratic sandstone of the 

Upper Triassic Shinarump conglomerate that fills stream channels scoured in 

the underlying Lower and Middle Triassic Moenkopi formation. These channels 

range from narrow and shallow, l.j feet wide and 10 feet deep, to broad and 

deep, 2,300 feet wide and TO feet deep. Two types of channels can be distinguished a short type, less than 2 miles long, and a long type, traceable for 

distances greater than 2 miles. Plant matter in the form of trees, branches, 

and twigs was deposited with Shinarump sediments in the channels. It is 

probable that when the Shinarump conglomerate was invaded by mineralizing 

solutions the uranium ore was deposited primarily in localities formerly occupied 

by the plant material. Also, it is thought that the short channels are more 

likely to have ore accumulations than long channels.

INTRODUCTION AND ACKNOWLEDGMENTS

During the summers of 1951 and 1052 the U. S. Geological Survey, 

on behalf of the Division of IJaw Materials of the U. S. Atomic 

Energy Commission, mapped the geology and uranium deposits in 

three 15-minute quadrangles on the Xavajo Indian Reservation in 

Apache and Xavajo Counties, northeastern Arizona (fig. 12). The 

area mapped includes the southern half of Monument Valley. The 

work was undertaken to establish guides to uranium deposits and to 

appraise the relative favorableness of different formations for the 

occurrence of uranium deposits. Special emphasis was placed on 

the study of the Shinarump conglomerate (Late Triassic) because all

0!)
100 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

oTUCSON

MEXICO"^___ |

FIGURE 12. Index map of part of the Monument Valley area in the Navajo Incl'an 

Reservation, Apache and Navajo Counties, Ariz.

uranium-ore deposits so far known in the Monument A7alley area are 

in Sliinarump sedimentary rocks which fill ancient channels at its 

base. In the Sliinarump conglomerate a close relationship exists between uranium-ore deposits and channel sediments.

D. W. Viles, vice president in charge of mining, Vanadium Corporation of America, kindly permitted access to the Monument No. 2 

mine by members of the Geological Survey. Our work in the mine 

was greatly assisted by Robert Anderson, mine superintendent, and 

Carl Bell, mine foreman.

GENERAL GEOLOGY

In Monument Valley, Ariz., exposed consolidated sedimentary 

rocks are of Permian, Triassic, and Jurassic age. (See geologic section below.) Most of the strata are continental in origin, eolian and 

water-laid rocks alternate in a nearly regular sequence. Volcanic 

necks and lamprophyric dikes, thought to be Tertiary in age, cut the 

sedimentary rocks. The dikes generally follow a joint set that trends
URANIUM DEPOSITS, MONUMENT VALLEY, ARIZONA 101 

Sedimentary rock's exposed in tlie Monument YaUcij Area, Arizona

Age

Jurassic

Jurassic (?)

Triassic

Permian

Stratigraphic unit

Group

San 

Rafael 

group

Glen 

Canyon 

group

Formation

Morrison formation

Bluff

sandstone

Summerville 

formation

Entrada sandstone

Carmel formation

Navajo sandstone

Kayenta formation

Wingate 

sandstone

Chinle formation

Shinarump 

conglomerate

Moenkepi formation

Cutler formation

Member

Salt Wash 

member

-Hoskinnini 

tongue

De Chelly 

sandstone 

member

Organ Rock 

tongue

Cedar Mesa 

sandstone 

member

Halgaito 

tongue

Thickness 

(feet)

?

45

35

110

118

665

150-200

Lithologic and topographic 

characteristics

Gray to chocolate-brown mudstone 

alternating with white to gray finegrained sandstone lenses.

Chocolate-brown fissile siltstone alternating with reddish-brown finegrained sandstone. Few discontinuous white siltstone lenses.

Brown to reddish-brown even-bedded 

siltstone; cliff former; white finegrained sandstone 1 foot thick at 

base.

Lower part reddish-orange mas live 

fine-grained sandstone that weathers 

as smooth, rounded slopes. Upper 

part chocolate-brown to reddishbrown even-bedded shaly siltstone 

and sandstone weathering to xounded 

structures resembling hoodoos. Base 

of upper part locally marked by 

white fine-grained sandstone 1 foot 

thick.

Predominantly red fissile siltstone 

with local lenses of red platy sandstone: few beds of discontinuous thin 

ledge-forming white crossbedded 

medium-grained sandstone.

Pink and buff massive eolian crossbedded sandstone with interbedded 

thin lenses of siliceous limestone.

Light-violet to reddish-brown irregularly bedded quartz sandstone with 

local lenses of conglomerate.

350 , Reddish-brown massive eolian crossbedded sandstone weathering to 

steep rounded slopes or vertical cliffs.

1. 1)00

50-100

30-250

10-60

 Uncoi 

350-450

650-750

500

380

Lower part, variegated mudstone and 

siltstone with dark sandstone lenses 

near base and thin beds of gray 

cherty limestone near top; upper 

part, reddish-brown even-bedded 

siltstone and sandstone weathering 

to rubble-covered slopes.

Light-gray fluviatile crossbedded conglomeratic quartz sandstone with 

rounded pebbles as much as 2 inches 

in diameter; much silicified wood 

present.

Reddish-brown even-bedded ripplemarked shaly siltstone weathering 

to gentle slopes.

Reddish-brown parallel-bedded siltstone with some interbedded lenses 

of sandstone.

Buff massive eolian crossbedded quartz 

sandstone weathering to steep 

rounded slopes or vertical cliffs.

Reddish-brown siltstone locally interbedded with red to gray sandstone; 

weathers to massive ledges about 5 

feet thick.

Reddish-orange crossbedded sandstone 

with thin beds of gray limestone.

Red siltstone and silty shale with thin 

beds of nodular-weathering gray 

limestone.
102 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

from due north to about X. 45° TV. Xenoliths in the volcanic necks 

are only moderately metamorphosed and include pre-Cambrian (?), 

Pennsylvanian, Permian, Triassic, and Cretaceous rocks. In many 

places all strata are masked by a thin veneer of alluvium or dune 

sand, but exposures on the mesa faces are excellent.

The major structural feature in the region is the Monument upwarp, 

a broad asymmetrical anticline. It extends from near the junction of 

the Green and Colorado Rivers in Utah southward into the Monument 

Valley area of Arizona (Baker, 1935, p. 1482) where it plunges southward and disappears. The upwarp is about 125 miles long and has 

a maximum width of about 75 miles. In the Monument Valley area, 

Arizona, (fig. 12) the eastern flank of the Monument upwarp dips 

steeply and is well defined by Comb Ridge; the western flank, however, clips gently, and its limits are poorly defined.

The gently dipping west flank of the upwarp is interrupted by 

northward-trending subsidiary folds. Like the major upwarp, these 

subsidiary folds are also asymmetrical, with steep eastern flanks and 

gently dipping western flanks. Extensive dissection along these 

structural features has produced the cuestas, mesas, and buttes that 

characterize the spectacular landscape of Monument Valley.

SHINARUMP CONGLOMERATE

In Monument Valley, Ariz., the only known uranium-ore bodies are 

in channel sediments at the base of the Shiiiarump conglomerate.

On weathered exposures the Shinarump is gray or light buff, and 

only locally does the color deepen to a more somber brown or gray. 

Fresh surfaces are much lighter, approaching a very light gray. 

Although called a conglomerate, the Shinarunip in Monument Valley 

is more correctly a conglomeratic sandstone. Commonly a coarse conglomerate is at the base, grading upward into sandstone that ranges 

from medium to coarse grained. Both the conglomerate and the 

sandstone beds are crossbedded and lenticular, and they intertongue 

with one another. Most of the foreset beds dip northwestward, but 

they may dip in any direction. Within any one lens the textures 

show rapid gradation; for example, a lens of coarse-grained sandstone 

more than 5 feet thick can become a conglomeratic standstone within 

a lateral distance of 10 feet.

The Shinarump conglomerate consists principally of only the most 

durable materials. Quartz, quartzite, and chert predominate both in 

the pebbles and the matrix. Pebbles composing the conglomeratic 

f acies are commonly well rounded, with smooth, unbroken surfaces and 

ellipsoidal shapes. They are white, red, black, green, and yellow, or 

have many color combinations. Small quantities of limestone, clay, 

and sandstone pebbles are found in a few localities. Silicified wood
URANIUM DEPOSITS, MONUMENT VALLEY, ARIZONA 103

is scattered throughout the Shinarump as fragments 1 or 2 inches in 

length and as logs as much as 50 feet long and 4 to 5 feet in diameter. 

Although much of the wood within the Shinarump has been silicified, 

some has not, and localized areas of small pockets of black carbonaceous material are found throughout the formation.

Lenses of claystone as much as 100 feet across and a few inches to 8 

feet thick are common in the uppermost parts of the conglomerate. 

In some places the clay is concentrated within the formation in the 

form of angular blocks that range from 4 feet long and 2 feet high 

to small clay pebbles 1 or 2 inches in diameter. In these localities 

more interstitial clay is present than in areas where clay pebbles are 

rare.

The formation is cemented by a number of materials either individually or in combination: authigenic quart/, iron oxide, calcite, and clay 

are predominant.

Despite the relative thinness of the Shinarump conglomerate in the 

Monument Valley area, it is remarkably uniform in thickness over its 

widespread area of outcrop. The formation is generally about 75 

feet thick, although locally, as the result of channeling, it thickens to 

150 feet or more; elsewhere, it thins laterally and disappears.

The contact of the Shinarump with the overlying Chinle formation 

is gradational, and, locally, the two formations intertongue. The 

contact between the Shinarump and the underlying Moenkopi formation, however, is a widespread disconformity marked by deep channels. Except for the channels the relief along the disconformity 

ranges from 2 to 4 feet and is marked by a notable textural and compositional change.

In Monument Valley the Shinarump forms a resistant sandstone 

ledge that caps most of the mesas. On outcrop it tends to form steep 

cliffs as much as GO feet high, that are almost unscalable for considerable distances along the exposure. The formation is jointed 

throughout, and large talus blocks mantle the slopes and commonly 

conceal the lower contact of the formation. Some talus slides extend 

from the base of the Shinarump cap to the bottom of the mesa, which 

is as much as 800 feet below. Where the Shinarump conglomerate 

forms a widespread surface, it is extremely irregular, pitted with 

basinlike depressions as much as 20 feet in diameter and 4 feet deep, 

and ridged with hummocks that rise as much as 30 feet above the general surface. In some localities the Shinarump forms a bench around 

the flanks of mesas capped by younger rocks.

CHANNELS

APPEARANCE

In Monument Valley the symmetric and asymmetric troughs that 

are cut into the Moenkopi and filled with Shinarump conglomerate

379273 56 2
104 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

are referred to as channels. These channels accentuate the disconformity between the two formations. Deposits of uranium and copper 

minerals are localized within these channel sediments, and as a result 

the channels are of special interest to geologists and prospectors in this 

part of the Colorado Plateau.

The channels are exposed in three different ways in the Monument 

Valley area. Principally, they are exposed along mesa rims and in 

valley walls as U-shaped depressions. In this mode of outcrop the 

channels are buried beneath overlying beds of Shinarump conglomerate (fig. 13J.). Where erosion has been more extensive and the overlying beds of Shinarump have been removed, the channel sediments 

appear as narrow elongate exposures of gray conglomeratic sandstone 

bounded by the red shaly siltstone of the Moenkopi formation (fig. 

135). Where erosion has proceeded still farther, the softer shaly 

siltstone of the Moenkopi has been removed, leaving the more resistant 

channel fills as ridges (fig. 13£7 and fig. 14).

The details of the origin of the channels are still in doubt, but it 

seems likely that the channels are the result of stream erosion. Typical 

cross sections of channels at the base of the Shinarump conglomerate 

are shown in figures 15,16, and 17.

CLASSIFICATION

The channels are difficult to trace commonly, because they are not 

well exposed or because they differ greatly in length. A channel may 

be so short that it is exposed only on one side of a mesa. This is well 

shown by E. A. Black and W. H. Jackson of the U. S. Geological Survey in their interpretations of the resistivity of the channels in the 

Koley Black area where channel 45 ends within 350 feet of the outcrop 

and cannot be traced farther to the northwest (fig. 18). The Koley 

Black group of channels (nos. 37-45 of fig. 18) has confirmed the short 

linear character of some channels. Other channels may persist across 

the mesa and be exposed on both sides. One channel was traced for 4 

miles; others disappear within a mile. I have called the shorter channels "short channels," and the longer ones "long channels," and have 

arbitrarily established the distance of 2 miles as a dividing line between the basinlike short channels and the more continuous long ones.

How the short channels terminate is uncertain, although the results 

of drilling by the U. S. Atomic Energy Commission suggest that 

some of the short channels have ends that are gently concave (pi. 5£7). 

Because of insufficient drilling it is not known how the long channels 

terminate.

These short channels may represent deep scours along the course 

of a former stream, but as yet I have not found these channels alined 

in such a manner as to confirm this. If these short channels do repre-
URANIUM DEPOSITS, MONUMENT VALLEY, ARIZONA 105

300

Approximate seal
106 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

EXPLANATION

Shinarump conglomerate

Moenkopi formation

Hoskmnini tongue

DeChelly sandstone member _

Contact, dashed where 

approximately located

Trend of known channel 

dotted where projected

FIGURE 14. Geologic map and cross section of Monument No. 1 channel, Navajo County,

Ariz.

sent sporadic scouring, it may be possible to project the trends and 

locate other short channels now concealed beneath overlying beds of 

Shinarump.

TRENDS

Iii this area the dominant orientation of the channels is northwestward (fig. 19). In an area as small as Monument Valley, Ariz., 

this northwest orientation is'merely suggested by a diagram of the 

channel trends (fig. 20A). This orientation is more apparent in the 

diagram of channel trends in the adjacent part of Monument Valley 

in Utah (fig. 207?). Thus, a diagram (fig. 20C) of all the channel 

trends noted in a much larger area (the Utah and Arizona parts of 

Monument Valley) clearly indicates the dominant northwest 

orientation.
URANIUM DEPOSITS, MONUMENT \ ALLEY, ARIZONA 107
r

FIGURE 16. Northeasterly view across the West Fork of Copper Canyon showing the broad deep Alfred Miles channel 1, 

Navajo County, Ariz., and the Shinarump conglomerate ("is), Moenkopi formation (~fim), Hoskinnini tongue of the Cutler 

formation (Pch), De Chelly sandstone member of the Cutler formation (Fed), and Organ rock inemhe:1 of the Cutler formation 

(Pco).
URANIUM DEPOSITS, MOXUMENT VALLEY, ARIZONA 109
110 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Monitor Butte member, 

Chmle formation

Shinarump conglomerate

Moenkopi formation

Hoskinnini tongue

DeChelly sandstone member

Resistivity data determined and interpreted by R. A. Black

and W. H. Jackson, U. S. Geological Survey 

EXPLANATION

Trend of known channel identified by 

number. Dashed where concealed, 

dotted where eroded

Outline of channel as interpreted from 

resistivity data: deeper scour within 

channel shown solid

Contact, dashed where approximately located

,3 

Strike and dip of beds

m90

Strike of vertical joint

X 

Prospect

FIGURE 18. Geologic and resistivity interpretations of channels in the Koley Black area,

Navajo County, Ariz.
-9S S1561S

nvA r 'ia VNOziav TTT
112

Number of observed channels 

with trend oriented in 10" 

segment

MONUMENT VALLEY, ARIZONA

Number of observed channels 

with trend oriented in 10° 

segment

MONUMENT VALLEY, UTAH

Number of observed channels 

with trend oriented in 10° 

segment

MONUMENT VALLEY-ARIZONA AND UTAH

FIGURE 20. Diagrams showing channel trends in the Monument Valley area,

Arizona and Utah.
URANIUM DEPOSITS, MONUMENT VALLEY, ARIZONA 113

Although several channels curve (fig. ID), most are nearly straight. 

This observation is substantiated by recent geophysical work in this 

area.

Single channels are most common, but several do bifurcate, and of 

these at least one, in the Koley Black area, appears to give way to 

a series of parallel smaller channels (fig. 18).

WIDTHS

For purposes of discussion the channels are classified roughly into 

three categories based upon width. The first category (narrow) includes channels as much as 50 feet wide, the second category (intermediate) comprises channels ranging from 50 to 350 feet in width, 

the third category (broad) includes channels ranging from 350 to 

2,300 feet in width (fig. ID). Of the G2 channels noted during the 

course of field work, IT were narrow, 32 were intermediate, and 13 were 

broad. (See table on following page.)

Channel sediments, sorting, and bedding appear identical in all 

three categories of channels.

FLOORS

Little is known about the configuration of channel floors. Judging 

from workings in the Monument No. 2 and Skyline mines (fig. 12), the 

floor is known to be unclulatory and locally extremely irregular. 

Geophysical work in the Koley Black area (fig. 18) and along the 

Alfred Miles channel 1 (fig. ID) has also indicated that broad shallow 

scours are in channel floors. It has been suggested by geologists of 

the U. S. Atomic Energy Commission (J. W. Chester, 1D52, personal 

communication) that these scours may be important centers of 

uranium-ore accumulation.

SEDIMENTS

Sediments filling the channels range from medium- and coarsegrained sandstone to conglomerate. Some of the channels are filled 

completely with massive uniform-textured medium-grained sandstone that is totally devoid of pebbles or conglomerate. Other channels contain conglomerate with minor amounts of coarse sand filling 

the interstices. In general, however, the sediments filling the channels 

appear identical with sediments found elsewhere in the Shinarump 

conglomerate. The prominent difference between channel sediments 

and nonchannel sediments is the amount of fossil wood; channel sediments contain abundant fossil wood, whereas nonchannel sediments 

contain less wood. For example, in certain channels, especially the 

Monument No. 2 channel, the quantities of mineralized wood seem unusually high. Some of this wood is replaced by silica, some by
114 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Characteristics of channels

Location 

number 

(fig. 19

1

2

3

4

5

6

9

10

12

13

14

17

18

19

20

21

99

23

24

25

26

27

29

30

31

32

33

34

35

36

38

39

40

41

42

43

44

45

46

47

48

49

50

53

54

55

56

57

58

59

60

61

62

Name of channel

Alfred Miles 1 

Double 1 -...... __ .....

Alfred Miles 2'. ......... i)

i)

i) 

Checker^ ............

Fishi... ..............

 . .do. .-..._-..

 .do- . . ...... ..

... ..do..... ... ... __

.....do. .............

 .do 

 do _

. .do ... 

 do 3 ...............

 .do .. .

 .do .... .... ...

Mitehell Mesa 3 . ......

Hunts Mesa 2... ____ ..

Width 

(feet)

2,150

2,300

1, 500

150

1,800

900

500

250

150

150

600

150

20

50

(?) 300

4-frn

4fin

30

100

4.K

600

140

250

300

250

50

25

15

250

250

80

50

50

50

35

110

35

270

35

110

150

150

(?) 350

300

70-80

50

150

50

300

400-700

150

300

Depth cut 

into 

Moenkopi 

formation 

(feet)

70

50

75

30

10

0

30

10

6

10-15

20-40

en

4n

40

10

20

30

20

10

30

75

50

20

20

15

8

50

30

50

25

5-10

5-10

20

30

25

30

20

30

30

16

50

75

70

15

20

20

20

50

20

25

40

20

Length

_____ do 

 do ..

.... do ......

 ..do 

.... do

 do 

..... do.. 

 do 

 do .....

Short (?)_ 

. do 

 do 

..... do ... ..

 do 

..... do 

 do 

Long (?)...._.

Short.--......

- do ......

Short.-. ..

_____do ... .....

Long (?)...___

Short.. -----

 do 

 do ....

 do 

--.do - .

 do- .

 do - -

 -do 

- do- .

 do .

 do 

 -do 

 do 

 ..do .....

Short --...

 _do

Short- .

 do 

 do 

-..-do -- 

i 

Strike

N. 50° E. ......

N. 35° E -

(?).. 

(?).. . 

N. 40° E. (?) 

East- -... __ .

East-. ___ . ...

N. 80° W_ ...

N. 80°E__ ..

(?)_. 

N. 12° E 

N. 72° E. .......

N. 55° E_ 

East 

NE (?) .....

N. 20° E... .... .

N. 25° W ....

N. 10° W ..

N. 40° E_ ....

N. 50° E.. ...

East. - .

N. 18° E._. __

N. 35° E. 

N. 25° E. ... .

N. 30° W.. .

N. 15° E. to N.

10° W. 

N. 65° W ..

N. 45° WN. 10° WNorth . .

North. .......

N. 65° E.... ....

N. 27° E. .

N. 80° E... ..

N. 35° W ...

N. 10° W 

N. 35° W 

N. 45° W_ 

N. 44° W 

N. 44° W 

N. 44° W 

N. 20°W 

N. 45°W 

N. 45°W 

N. 52° W 

N. 20° W- .

N. 45° WN. 50° W... .....

N. 70°W .... .

N. 82° E.. __....

N. 85° W .

N. 75° E (?). .

N. 85° E. .......

N. 82° E.. ...

East 

N. 18° W ..

N. 25° W_ ...

N. 55° W. ...

N. 67° E.. .....

N. 50° W ...

Mineralization

Cu, U.

Cu.

Do.

Cu.

Cu^U.

Cu.

Do.

Cu.lU.

Cu.

Cu.

Do.

Cu, U.

Cu, V.

Cu.

Do.

Cu, U.

Do.

Cu, U, V.

1 One channel (?).

2 Koley Black refers to a group of unnamed channels in the Koley Black area.

3 Main channel of the Koley Black group.

tyuyamunite and limonite, some by uraninite, and same has been 

altered to a carbonaceous material. Furthermore, many of the rich 

ore bodies at the Monument No. 2 mine may represent deposition of 

uranium minerals in localities once occupied by buried logs. In several other channels, notably the Alfred Miles channels 1 and 2, and
URANIUM DEPOSITS, MONUMENT VALLEY, ARIZONA 115

the Double channel (fig. li>), fragments of wood partly replaced by 

copper minerals (aznrite and malachite) are found in basal channel 

sediments. Lenticular pods of black coaly material (vitrain?) have 

been found associated with several ore deposits and are believed to 

represent buried logs.

It appears that two types of clay fragments are included in the 

Shinarinnp conglomerate. Most profusely distributed are those fragments derived from the Moenkopi formation. Other clay fragments, 

less common, may be the result of alteration of volcanic ash deposited 

during original accumulation of the Shinarnmp (Waters and Granger,1953,p. 6).

In the Skyline mine (fig. 12) angular boulders of clay, derived from 

the Moenkopi formation, as much as 4 feet on a side, and clay fragments of smaller sizes are profusely distributed throughout the channel sediments. Similar clay fragments are found in other channels. 

Preliminary X-ray work by D. H. Johnson of the Geological Survey 

has indicated that most of these clay pebbles are composed of quartz, 

hydromica, and possibly a little montmorillonite. (See table below.)

Whether either type of clay fragment is instrumental in the localization of uranium ore is unknown. Conflicting9 evidence has been 

noted at several mineralized locations. Geologic mapping in the 

Monument No. -2 mine has suggested that clay has no significance in 

such localization, but at both the Monument No. 1 and the Skyline 

mines clay pebbles appear to have acted as focal points for the accumulation of uranium minerals.

Composition of some clay i>c1>l>les from tlie ^Lonnmrvt Valley area, Arizona and

Utali, ax determined by means of the X-ray spectrometer 

[Analyzed and compiled by 1). H. Johnson, Denver Trace Elements Laboratory]

Sample 

no.

W-175A.. 

W-175B.. 

W-176A.. 

W-176B..

W-182-... 

W-186 .

W-187. 

W-188.

Location

Monument No. 1 mine, Navajo 

County, Am.

Base of channel, Monument No. 1

mine, Navajo County, Ariz, 

.....do. _.-___..._-...._..__..

Composition

Monument No. 1 mine, Navajo 

County, Ariz.

Monument No. 1 Annex, Navajo

County, Ariz. 

Skyline mine, San Juan County,

Utah.

.do.

Quartz, hydromica, and a little kaolinite.

Quartz, hydromica, and carbonate 

apatite (?).

Quartz, hydromica, and a little carbonate apatite (?).

Quartz, hydromica, and a little carbonate apatite (?) and kaolinite or 

chlorite.

Quartz, hydromica, a little kaolinite, 

and possibly a little montmorillonite.

Quartz, hydromica, and probably a 

little montmorillonite.

Quartz and hydromica._-_-------.--..

Quartz, hydromica, and perhaps 

little montmorillonite.

Beiizidine test

Very slightly 

positive (?). 

Do.

Very slightly

positive. 

Negative.

Very slightly 

positive.

Do. 

Do.

Do. 

Do.

SWALES ASSOCIATED WITH CHANNELS

The Monument Xo. 2 channel is in the center of, and collinear with, 

a broad very shallow, elongate swale in the top of the Moenkopi formation (pi. fi). However, this cannot be perceived from the ground
116 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

because of the dissection of the area, as well as the great width and 

relative shallowiiess of the feature. An isopachous map, prepared 

from measured sections of the combined Hoskinnini and Moenkopi 

strata indicates its width and extent clearly (pi. 6). The swale is 

about 3 miles wride and can be traced southeastward for S1/^ to 4 miles 

before it disappears below the alluvium of Cane Valley. At the edges 

of the swale the combined thicknesses of Hoskinnini and Moenkopi 

strata amount to about 80 feet. Along the flanks of the Monument 

No. 2 channel in the center of the swale, this thickness decreases to 30 

feet. Erosion during the formation of the channel has removed these 

30 feet of strata adjacent to the channel, and consequently channel 

sediments of the Shinarump conglomerate rest with pronounced disconformity on the De Chelly sandstone member of the Cutler 

formation.

Although this swale-channel relationship is best displayed in the 

Monument No. 2 area, analogous features have been noted on Hoskinnini Mesa. There, however, the swales are not as well formed nor as 

broad.

ORIGIN

One hypothesis regarding the origin of channels suggests that they 

were formed during a period following deposition of the Moenkopi 

formation but prior to deposition of the Shinarump conglomerate. 

This viewpoint is presented by Gregory and Moore (1931, p. 52) who 

wrote 

After Moenkopi time there was widespread erosion which partly beveled the 

soft Moenkopi strata and in places carved distinct erosion channels in them. 

The subsequently deposited Shinarump conglomerate constitutes a very widespread thin veneer which covers this erosion surface and fills its depressions.

Stokes (1950, p. 94) interprets this as meaning that the unconformity and the channels were formed probably during Middle Triassic, with the Shinarump deposited much later in a second independent episode in Late Triassic time.

Another hypothesis suggests that the channels were formed by 

the streams that deposited the Shinarump, and thus are contemporaneous in age with basal Shinarump sedimentary rocks. This viewpoint is expressed by Stokes (1950, p. 97) who regards the unconformity as a Middle Triassic pediment surface formed during the 

deposition of the Shinarump conglomerate, which in turn represents a 

pediment deposit.

Essentially there appears to be general agreement that the Shinarump was deposited on a widespread surface of low relief. Stokes 

considers the surface to have formed synchronously with the deposition of the Shinarump; McKee (1951, p. 91), however, considers it 

to have been a flood plain upon which the Shinarump was deposited,
URANIUM DEPOSITS, MONUMENT VALLEY, ARIZONA 117

Apparently streams transported sands and gravels from a raised 

area to the south and gradually spread them northward as a thin 

blanket. When one considers the coarse-grained and resistant materials that compose the Shinarump conglomerate it seems unlikely 

that the formation could have been deposited without some scouring 

in the softer siltstones and shales of the underlying Moenkopi formation. It is suggested, therefore, that the major channel scour occurred 

during deposition of the Shinarump conglomerate and not, in any 

period of erosion prior to this deposition.

Why one channel is continuous and another not, is unknown; the 

short channels may represent sporadic scour depressions. Bryan, 

(1920, p. 191) in discussing present streams, suggests that scour 

depressions are most likely to form near the outside bend of a stream 

where the erosive force of the stream is at a maximum. If this 

concept is applied to the Shinarump, it may be that a former meandering stream, carrying Shinarump sediments cut these deeper scours 

wherever it swung about. Thus, Monument No. 1 (tig. 14), a gently 

curving short channel, might have formed in this manner.

Another possibility is that local differences in the hardness of the 

Moenkopi formation that once formed the banks of the former streams 

may have caused the formation of "'narrows". These narrows may 

have been instrumental in ponding the water and thus forming sizable 

lakes upstream. The attendant increase in gradient across the 

more resistant rocks would have augmented the velocity. Downward 

erosion would have increased at the expense of lateral planation, and 

the tinal result would have been the formation of short channels. 

Matthews (1917, p. 307-3-42), referring to elongate scour depressions 

as much as 2,000 to 7,200 feet long, 200 to 300 feet wide, and 40 to 60 

feet deep in the floor of the Susquehanna River, suggests that these 

""deeps," as he calls them, are the result of such constrictions.

LOCALIZATION OF URANIUM ORE IN CHANNELS

This paper is concerned with the localization of uranium minerals, 

which are more correctly identified as uranium-vanadium minerals 

inasmuch as the chief ones are tyuyamunite [Ca (UO2 ) 2 (V(X) 2 nH2 O] 

and carnotite [K2 (UO2 ) 2 (V(X) 2 3H2O].

Although uranium ore is in channel sediments, the ore is not continuous along the channel's length nor does it appear to be restricted 

to any specific sector of the channel sediments. At the Vanadium 

Corporation of America's Monument No. 2 mine, where extensive 

workings permit examination of channel sediments, ore has been found 

in the basal, middle, and uppermost beds as well as along the channel 

flanks.
118 CONTRIBUTIONS TO THE GEOLOGY OF URA.NIUM

One fact, however, is clearly evident in the Monument Valley area: 

no ore has been found outside of channels. This is not to be construed to mean that uranium minerals are not found away from channels ; they are, but to date they have been found in such small amounts 

as to make them of academic rather than economic interest. This 

relationship between uranium ore and channels is well known, and 

most prospectors seek and stake claims on such channels.

The relationship between uranium minerals and channels is repeated 

many times in the Monument Valley area of Utah and Arizona. Generally, these exposures are small and of slight extent, but more than 

one-third of the channel outcrops examined contain some uranium or 

copper minerals in their basal sediments.

The spatial relationship between uranium-ore deposits (economic 

concentrations of uranium minerals) and channels, is based on only 

two examples. Essentially, in the Monument Valley area, Arizona, 

uranium-ore deposits have been found in one of the intermediate-type 

channels, and in one of the broad channels. Despite this unimpressive accounting, it should be noted that many of the channels are as 

yet untested and may contain deposits of uranium ore. Most important, however, is the realization that of the thousands of miles of 

Shinarump outcrop examined, deposits of uranium minerals seem to 

be largely restricted to channel sediments. The apparent relationship 

between channels and uranium-ore deposits also seems to be suggested 

elsewhere on the Colorado Plateau.

As a result of the spatial association between channel sediments and 

uranium ore, a continuing search is underway for the factor or factors 

which were instrumental in localizing the ore in the channel sediments. 

The search has been unsuccessful in that conclusive evidence favoring 

any factor (or combination of factors) is yet to be produced. Strong 

"suggestions" have been noted by field geologists working in the Monument Valley area. For example, at the Skyline mine, ore is in channel 

sediments that contain much clay and pods of carbonized wood. A 

similar situation exists at Monument No. 1 mine. Despite this apparent relationship in these two localities between clay and carbonized 

wood and uranium ore, it is difficult to state conclusively what role 

these factors played in the localization of uranium ore. Clay as well as 

pods of carbonized wood are found away from channels, and ore is not 

present in these localities. In Monument No. 2 mine clay and carbonized wood are in considerable amounts within the channel sediments, 

but in no instance was a sizeable quantity of uranium ore associated 

with either. In fact, areas were found in the mine where concentrations of clay, boulders, and carbonized wood were distant from ore 

localities.
URANIUM DEPOSITS, MONUMENT VALLEY, ARIZONA 119 

BODS

Throughout the Monument No. 2 mine many of the major bodies of 

uranium ore appear as flattened, cylindrical bodies. The miners 

refer to them as trees or logs. Because these two terms bear a genetic 

connotation, a new term, suggested by L. B. Riley of the U. S. Geological Survey, is proposed herewith. It is suggested that these crudely 

ovate, flattened, elongate, cylindrical bodies be known as rods.

All the rods are in channel sediments of the Shinarump conglomerate; none are in any of the underlying strata. Ore bodies similar to 

these have been noted in the Morrison formation and called cylindrical 

masses (Coffin, 11)21, p. 103). The origin of these rods in the Shinarump is obscure. Some may result from chemical changes induced in 

the mineralizing solutions by carbonaceous matter; others may result 

from unusual conditions of permeability and porosity in the host rock.

The rods in the Shinarump can be classified roughly into two categories : simple and complex. The simple type of rod is illustrated in 

figure 21. Essentially it consists of an outer rim of sandstone impregnated with limonite, within which is a rim of tyuyamunite-impregnated sandstone, which in turn surrounds a core of extremely friable 

light-gray sandstone.

The complex type of rod is bounded similarly by an outer rim of 

limonite-impregnated sandstone within which is a rim of tynyamuniteimpregnated sandstone. These rims, however, are much more irregular than in the simple type. A further subdivision of the complex 

rod is possible. One type contains irregular masses of mixed limonite 

and tyuyamnnite randomly distributed throughout the gray sandstone 

center (fig. 21A and fig. 22) ; a second type may have these irregular 

masses of limonite and tyuyamunite in the sandstone center, but in 

addition has a central core of silicified wood (figs. 21Z>, 23, and 24).

Near many of the rods the confining strata are interrupted at the 

rims; elsewhere, they arch over the rods. Grain size changes abruptly 

at the edges of some rods. Most rods are remarkably straight and, 

where mining operations have followed them, many have been found 

to taper and bifurcate. Many complex rods are associated with silicified wood; and, invariably, where longitudinal exposures are available, 

the silicified wood is seen to be collinear with the rods (block diagram 

in fig. 21; and fig. 24). In several rods, exposures are large enough 

to afford longitudinal examination of the gray sandstone core filling 

their centers. In these, the direction of crossbedding is totally different from the direction of crossbedding of those sediments outside 

the rods.

Small fractures cutting the sand grains are restricted to the limonite-impregnated sandstone zone and the tyuyamunite-impregnated 

sandstone zone, both of which form the rims of the rods. These
120 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

fractures are not apparent in those grains that fill the cores of the 

rods, nor in the grains distant from the boundaries of the rods. Moreover, the fracturing halts along very definite boundaries which in 

some cases are so distinct they can be delineated in thin section. For 

example, in thin sections of edges of rods, the grains on part of the 

s-lide are intensely fractured, whereas the grains on the remainder of

-Circular pattern of fractures 

""" ^ X" -Limonite

^4 

 Gray friable sandstone /

' ^J!/

-Tyuyamunite 

Simple rod ~~\^^' "-^ x Gray friable sandstone

Complex rod A

Tyuyamunite, limonite, and 

gray sandstone core

3 Feet

Gray friable sandstone

Complex rod B

Silicified wood core

Gray friable sandstone 

Silicified wood

FIGUKE 21. Illustrations of simple and complex rods in Monument No. 2 mine. Apache

County, Ariz.
FIGURE 22. View of large complex rod in Monument No. 2 mine, Apache County, Ariz., showing mixed limonite and tyuyamuiiite (ss) 

in sandstone center, surrounded by rings of tyuyamunite (ty) and limonite (It).
122 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

_-«- ft
URANIUM DEPOSITS, MONUMENT VALLEY. ARIZONA 123

./' w i

. te.. '~
124 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

FIGURE 25. Photomicrographs of thin sections of specimens collected in the Monument 

No. 2 mine; specimens contain secondary uranium and vanadium minerals in interstices 

and fractures. A., Rim of rod showing distinct boundary between fractured and unfractured grains. B, Rim of rod showing quartz grains broken by parallel set of 

fractures.
URAXFTM DEPOSITS, MONUMENT VALLEY, ARIZONA 125

i'MGUKE 2(5. - Photomicrograph of thin section of specimen ^ollected in the Monument No. 

2 mine, showing irregular fractures of channel sediments about 1 foot away from rim 

of rod. Specimen contains secondary uranium jind vamulinm minerals in interstices 

and fractures.

the slide are whole (fig. 25). The separation between fractured and 

unfractured grains is a zone not more than 1 mi 11imeter wide.

Two systems of fractures were noted: une consists of a set of parallel 

fractures (fig. 26) with a subsidiary set trending more or less at right 

angles; the other is a plexus of fractures that lacks orientation. Each 

fracture of the parallel set is as much as 1 millimeter away from 

adjacent fractures, and each fracture can be traced for as much as 

10 to 15 millimeters in a relatively straight line as it continues uninterrupted through sand grains. In places this parallel set is cut 

by a subsidiary set that is at right angles to the. main set. The subsidiary set offsets the main fractures slightly; but those fractures with 

no determinable pattern are ]ess common. The fractures are jagged 

and end at the grain boundaries. The. gross appearance of this 

fracture system is that of an interlacing network, devoid of orienta- "' ~ /

lion or system.

Filling the fractures, interstices, and other voids are secondary 

uranium and vanadium minerals, calcite. and authi genie quartz. The 

depositional sequence appears to be as follows: First, authigenic 

quartz; second, secondary uranium tiiid vanadium minerals; and third, 

emplacement of calcite.

The circular pattern formed by the fractures as they outline the 

rods is distinctive and has been found only in the Monument Xo. 2 mine.
126 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

How these circular fracture patterns form and the reason why some 

grains are fractured whereas others only a few millimeters away are 

not fractured is unknown. One answer may involve factors of selective cementation. Perhaps those grains in the fractured zones were 

once tightly cemented. When stress was applied, possibly as a result 

of load, the cemented grains may have fractured, but the imcemented 

grains may have merely rolled and readjusted themselves to the forces 

applied.

Many of the rods were interpreted by me to represent replacement 

of coalified logs by silt, pyrite, and uraninite. Subsequent oxidation 

altered the pyrite to limonite, and the uraninite to becquerelite and 

carnotite. It was thought that the woody texture of these coalilied 

logs is now reflected in the rims of the rods by these materials. To 

test this concept, six samples were sent to James M. Schopf of the 

Geological Survey. Five of the samples were collected from the rims 

of the rods, and the sixth was collected from silicified wood in the core 

of a rod. It was requested that he determine whether any of the 

samples represented replaced plant matter. In selecting the samples 

an effort was made to include a range from those that seemed to show 

woody texture to others that appeared to contain only rudimentary 

traces of former plant matter.

Of the six samples submitted, Schopf identified only one as replaced fossil wood, and that was the one collected from the core of 

the rod; the others contained no trace of organic matter. It appears, 

therefore, that although parts of some rods may represent replacement of some form of former plant matter, the mineralized rims of 

the rods do not show this phenomenon. The similar pattern between 

trends of rods and of silicified wood fragments (fig. 27), however, 

as w^ell as the collinearity apparent between many of the rods and 

silicified remnants of logs, suggests that some relationship does exist 

between these former buried logs and the rods.

Possibly the shape, size, and distribution of the rods were determined by the buried logs. During or very shortly after burial the 

original organic matter of the buried logs may have been removed 

and other, more stable materials, such as sand, silt, and clay may have 

been deposited in the voids so formed. The removal of the organic 

matter and its subsequent replacement was probably a 'gradual process 

and affected only part of any log at any one time. It may have been 

during this episode that porosity and permeability conditions were 

changed; possibly this was sufficient to localize the ore solutions when 

they invaded the Shinarump conglomerate. Thus, those rods over 

which the bedding arches, as well as those that show abrupt changes 

in grain size between the confining strata and the rod boundaries, 

may merely represent the former presence of buried logs, which have 

since been replaced by sand, silt, and clay.
URANIUM DEPOSITS, MONUMENT VALLEY, ARIZONA 127

Number of observed fractures 

oriented in 10° segment

FRACTURES

Number of observed rods 

oriented in 10° segment

RODS

Number of observed silicified-wood 

N. frogments oriented in 10° segment

SILICIFIED-WOOD FRAGMENTS

FlGt'EE 27. Diagrams comparing orientation of fractures, rods, and silicified wood 

fragments in Monument No. '2 mine, Apache County.
128 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Other rods may have formed from mineralizing solutions in response to halos of decomposition products, such as humic colloids and 

organic resins, spreading outward from buried coalified logs. Possible examples of this type are those rods that contain silicified wood at 

their centers.

Still another possibility is that the rods may be completely independent of plant matter and may merely reflect fracture patterns 

formed during processes of compaction and authigenic crystal growth.

Probably no single concept will explain how rods formed. Perhaps 

combinations of the processes mentioned above are involved. For instance, the shape, size, and distribution of the rods may have been 

determined by the presence of buried logs. During or shortly after 

the logs were buried, their rims may have been partly replaced by 

more stable materials. If at this time compaction and authigenic 

crystal growth began, fracturing may have occurred along the zones 

represented by the former edges of the logs. In the voids formed by 

this fracturing, the ore solutions may have deposited their minerals.

Although the rods constitute the richer concentrations of ore, considerable quantities of secondary yellow uranium minerals are found 

elsewhere and in different forms in channel sediments. Thus, in much 

of the conglomeratic sandstone exposed between rods, yellow uranium 

minerals fill interstices and coat pebbles and fractures. Although 

rods are not present in the De Chelly sandstone member, yellow uranium minerals coat cross-lamination planes, fill fractures, and also impregnate the sandstone. The concentration of uranium minerals in 

sediment between rods and in the De Chelly is low. These weakly 

mineralized localities are believed to represent secondary migration 

by percolating ground water. Most of the uranium minerals are 

thought to have been leached from the richer ore bodies represented by 

the rods, and then moved short distances both laterally and vertically 

before being deposited once again in the matrix of the sandstone.

Fischer (1947, p. 455), in discussing the vanadium deposits of the 

Colorado Plateau, implies that a close affinity may exist between 

vanadium deposits, channel sediments, and organic matter in the 

Morrison formation of Jurassic age. In a later report, still referring 

to the Morrison formation, Fischer and Hilpert (1952, p. 12) indicate 

that although fossil plants are erratically distributed most of the 

carnotite deposits are in parts of the sandstone that contain fairly 

abundant plant remains. From my observations in the Monument 

Valley area on the habits of uranium ore in the Shinarump conglomerate, I concur with Fischer and Hilpert and believe that a close spatial 

relationship exists between pockets of uranium ore, channel sediments, 

and former plant matter.
URANIUM DEPOSITS, MONUMENT VALLEY, ARIZONA 129

The channels, apparently, were places where plant matter was concentrated. Trees growing along the flanks of these channels may 

have fallen into them and then have been buried by the channel sediments. Other trees and organic material may have been rafted into 

the channels and buried. Subsequently, when mineralizing solutions 

moved through the Shinarump, favorable conditions of permeability 

and porosity resulting primarily from the former presence of buried 

logs may have been responsible for the formation of the rods.

Not all channels contain known uranium deposits even though they 

may contain organic matter. One possible explanation for the lack 

of ore in some channels is that ore may have been deposited but was 

later leached by ground water. The great length of long channels, 

for example, may have permitted accelerated movement of ground 

water solutions resulting in more effective leaching of ore. Conversely, leaching would have been less effective in the short channels. 

A final result would be ore accumulations in short channels and 

essentially barren strata in continuous channels.

SUMMARY

Six stages are proposed in the localization of uranium ore to achieve 

present conditions in Monument Valley, Ariz.: (1) Cutting of 

short and long channels prior to or during deposition of Shinarump 

sediments; (2) burial of plant matter (trees, branches, and twigs) 

in channels synchronously with deposition of Shinarump sediments; 

(3) some form of alteration of the plant matter resulting in unusual 

conditions favoring the precipitation of uranium minerals; (4) invasion of Shinarump sediments by mineralizing solutions; (5) precipitation and localization of uranium ore from these solutions 

primarily in localities formerly occupied by plant matter; and (6) 

leaching and movement of uranium minerals by ground water out 

of the continuous long channels, and retention of uranium minerals 

in the short channels.

LITERATURE CITED

Baker, A. A., 1935, Geologic structure of southeastern Utah: Am. Assoc. Petroleum Geologists Bull., v. 19. p. 1472-1507.

Bryan, Kirk, 1920, Origin of rock tanks and chare* >s: Am. Jour. Sci., 4th ser., 

v. 50, no. 297, p. 188-200.

Coffin, R. C., 1921, Radium, uranium, and vanadium deposits of southwestern 

Colorado : Colo. Geol. Survey Bull. 16.

Fischer, R. P., 1947, Deposits of vanadium-bearing sandstone, in J. W. Vanderwilt, Mineral resources of Colorado: Denver, Colo., Colo. Min. Res. Board, 

p. 451-45G.

Fischer, R. P., and Hiliiert, L. S.. 1952. Geology of the Uravan mineral belt: 

U. S. Geol. Survey Bull. 988-A.
130 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Gregory, H. E., and Moore, R C., 1931, The Kaiparowits region, a geographic 

and geologic reconnaissance of parts of Utah and Arizona: U. S. Geol. 

Survey Prof. Paper 164.

Mathews, E. B., 1917, Submerged "deeps" in the Susquehanna River: Geol. 

Soc. America Bull., v. 28, p. 335-346.

McKee, E. D., 1951, Triassic deposits of the Arizona-New Mexico border area: 

N. Mex. Geol. Soc. Guidebook, 2d Fiekl Conf., p. 85-91.

Stokes, W. L., 1950, Pediment concept applied to Shinarump and similar conglomerates : Geol. Soc. America Bull., v. 61, no. 2, p. 91-98.

Waters, A. C., and Granger, H. C., 1953, Volcanic debris in uraniferous sandstones, and its possible bearing on the origin and precipitation of uranium: 

U. S. Geol. Survey Circ. 224.

O