DEPARTMENT OF THE INTERIOR

HUBERT WORK, Secretary

UNITED STATES GEOLOGICAL SURVEY

GEORGE OTIS SMITH, Director

Bulletin 764

PHOSPHATE DEPOSITS IN THE WIND RIVER 

MOUNTAINS, NEAR LANDER, WYOMING

BY

P. DALE CONDIT

WASHINGTON

GOVERNMENT PRINTING OFFICE 

1924
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CONTENTS -.--. .-- - -

	Page

Introduction ___ 1

General considerations _ 1

Field work_ 2

Geography____ 3

Geology : 6

Stratigraphy. 6

Pre-Cambrian rocks . 6

Flathead sandstone____ _ _____ 7

Gros Ventre formation__ 7

Gallatin limestone ________ __ 8

Bighorn dolomite 8

Devonian strata___________________ _ ' 9

Madison limestone_____ _ _ 9

Amsden formation_______ _ 9

Tensleep .sandstone_____ _ _____ ___ __ 10

Embar formation of Darton __ 10

Phosphoria formation ______________________ 11

Dinwoody formation_ __ _ ____ 13

Chugwater formation___ _ _ 13

Sundance formation _____ ___ __ _______ 14

Morrison formation and other Lower Cretaceous (?) rocks..___ 14

Cretaceous strata.______ ________ _______ 15

Tertiary strata _ 15

Glacial .drift (Pleistocene)._ __________________ 16

Terrace gravel_____________________________ 16

Structure ___________________________________ 17

Township descriptions______________________________ 17

T. 1 N., R. 3 W_________________________________ 18

T. 1. S., Rs. 2 and 3 W___________________________ 19

T. 2 S., Rs. 2 and 3 W_____________________________ 20

T. 33 N., R. 101 W_________________________________ 21

T. 33 N., R. 100 W_________________________________ 22

T. 32 N., R. 100 W_________________________________ 23

T. 31 N., R. 99 W_________________________________ 25

T. 30 N., R. 99 W__________________________________ 27

T. 30 N., R. 98 W_________________________________ 29

Sheep Mountain anticline, T. 30 N., R. 97 W., and T. 31 N., Rs. 97

and 98 W__________________________________ 30

Summary of phosphate beds___________________________ 33

Character of the phosphate rock_______________________ 35

Physical properties _____________________________ 35

Composition____________________________________ 36

Utilization and methods of treatment_____________________ 36

Index ____________________________ 39

in

ILLUSTRATIONS i

Page

PLATE I. A, View northeastward across Wind River Basin from slope of 

Wind River Range in T. 5 N., R. 6 W.; B, View eastward 

toward head of Red Creek canyon in T. 31 N., R. 99 W_ 10 

II. A, Exposures of Phosphoria formation in canyon of South Fork 

of Popo Agie River; B, Typical exposure of chert beds 

overlying upper phosphate beds on South Fork of Popo 

Agie River______ _________ _____ _______ 11

III. Geologic map of northeastern slope of Wind River Mountains

near Lander_____________________________ 18 

FIGURE 1. Index map showing coal, oil, and phosphate fields of west-central Wyoming and areas covered by publications of the Geological Survey concerning them________________ 2

v

PHOSPHATE DEPOSITS IN THE WIND EIVER MOUNTAINS 

NEAE LANDER, WYOMING

By D. DALE CONDIT

INTRODUCTION

GENEBAL CONSIDERATIONS

The Eocky Mountain phosphate fields include beds of high-grade 

rock which underlie many thousands of square miles in Montana, 

Idaho, Wyoming, and Utah. The rock has been mined during the 

last several years at six or seven places, all within about 50 miles 

of Bear Lake, in southeastern Idaho and adjacent parts of Wyoming 

and Utah. The quantity of rock sold in 1920, the banner year, was 

55,609 tons, but in 1922 it had dropped to 4,481 tons, although in that 

year 17,481 tons Was actually produced. The output has never exceeded a small fraction of that of the entire United States, and the 

greater part of it has been shipped to California for treatment and 

use in that State by orchardists and gardeners as a strengthener of 

the soil.

In the Rocky Mountain States, where intensive cultivation has not 

yet been practiced to any considerable extent and where the arable 

lands are largely planted in 'alfalfa and other hay crops, the practice of using phosphate rock and other fertilizers has not yet become 

general, and the naturally rich soil has been made to produce the 

same crop year after year without restorative treatment. The depletion of the potash, phosphate, nitrogen, and other constituents 

of the soil that are essential to fertility is already noticeable in the 

wheat-producing areas, where there has been a progressive diminution in the yield per acre in recent years. The time is at hand 

when much of this land must be artificially renewed just as it h'as 

been renewed in the corn belt of the Mississippi Valley.

It is therefore opportune to call attention to the phosphate deposits in the Wind River Mountains, in west-central Wyoming (see 

fig. 1), which through their geographic position some 150 miles e'ast 

of the main barriers of the Rocky Mountains possess advantages 

over the phosphate deposits in Idaho in respect to transportation to 

the wheat belt of the Great Plains region. These deposits have the

1
2 PHOSPHATE IN WIND RIVER MOUNTAINS, WYO.

added advantage of being close to Lander, the terminus of the Chicago & Northwestern Railway, which follows a direct, mostly downgrade route to the East and which is not alre'ady encumbered with 

transcontinental freight traffic. This line has ready access to the 

Burlington and other connecting railroads, which would facilitate 

ready distribution in all directions.

FIGURE 1. Index map showing coal, oil, and phosphate fields of west-central Wyoming 

and areas covered by publications of the United States Geological Survey concerning them. The area described in the present report is indicated by shading.

FIELD WORK

The'field work upon which this report is based was done under 

the supervision of Eliot Blackwelder during the summer of 1913. 

The work was begun early in July in the vicinity of Dubois, at the 

upper end of Wind River Basin. There were two parties, one under 

Mr. Blackwelder, doing detailed work in the Owl Creek Mountains, 

and the other under the writer, following the northeast slope of the 

Wind River Range. In the work along the 50 miles of mountain 

front described in this report the writer was joined by A. R. Schultz, 

chairman of the phosphate committee of the land-classification board 

of the United States Geological Survey, whose able assistance greatly 

facilitated progress. In the early part of the season Hyrum Schneider was also a member of the party in the capacity of geologic aid. 

The examination of the Wind River Mountain front was completed
GEOGRAPHY 3

about October 10, and the writer then took up the work in the Owl 

Creek Mountains, which was pushed until snow came the first week 

in December.

During the course of the work the members of these parties were 

treated with uniform courtesy by the residents of the districts. 

Among those to whom thanks are especially due for favors are Mr. 

N. H. Brown, of Lander, and officials of the Shoshone Indian Reservation at Fort Washakie.

The detailed work in 1913 was preceded by a reconnaissance survey by Eliot Blackwelder, who in 1910 visited a number of localities 

in the Wind Kiver Range and collected data concerning the phosphate beds.1 In addition he made a study of the stratigraphy and 

other general geologic problems, some of which were discussed in 

a preliminary paper. 2 In the description of the early Paleozoic 

stratigraphy the writer has made free use of the data in this paper.

GEOGRAPHY

The rugged topography of the Wind Eiver Mountains is the result of somewhat advanced erosion of rocks that have been folded 

into a great anticline. Along the axis of this anticline the limestone, 

sandstone, and shale formations of the Paleozoic sequence have been 

entirely removed, laying bare the crystalline gneisses and schists, 

which rise in numerous snoAvy alpine peaks to an altitude of more 

than 13,000 feet. Toward the Avestern part of the range, where the 

topography is most rugged, there are many small glaciers, whose 

grinding action on their rock floors contributes a rock powder to the 

mountain torrents, giving the water a milky appearance. The sedimentary formations overlap one another successively, in shingle-like 

fashion, the physiographically strong formations forming long dip 

slopes, which are furrowed at short intervals by sharp transverse 

canyons, most of which are occupied by permanent streams.

The basin topography of the Wind River valley may be said to 

begin with the "Red Beds," which rise in low hogback hills along 

the base of the mountains and are generally separated from the 

limestone dip slopes of the mountains by an inner lowland, commonly occupied by small streams parallel to the strike, such as Red 

Canyon Creek, a tributary to Little Popo Agie River from the 

south. From the " Red Beds" basinward there are successively 

lower hogback ridges formed by interbedded layers of Mesozoic 

sandstone and shale. The line of elongated anticlinal domes that 

extends from the vicinity of Fort Washakie southeastward past

1 Blackwelder, Eliot, A reconnaissance of the phosphate deposits in western Wyoming: 

U. S. Geol. Survey Bull. 470, pp. 452-481, 1911.

2 Blackwelder, Eliot, New geological formations in western Wyoming: Washington 

Acad. Sci. Jour., vol. 8, No. 13, pp. 417-426, 1918.

5525 24 2
4 PHOSPHATE IN WIND EIVEE MOUNTAINS, WYO.

Lander parallel to the mountains brings the "Red Beds" again to 

the surface and produces a characteristic topography.

At many places in Wind River Basin and well up the adjoining 

mountain slopes^there are conspicuous gravel-covered terraces that 

denote different stages in the erosion of the basin. Table Mountain, 

near Lander, and the divide at the head of Red Canyon Creek, to 

the south, are examples of these terraces, being mesas cut on tilted 

strata and capped with coarse gravel. (See PL I, B.) Another mesa 

related to these is on the north side of North Fork of Little Wind 

River. These mesas, which range in altitude from 7,200 to 7,700 feet, 

are merely remnants of a once extensive plain over which were spread 

outwash deposits from the mountain front. Successively lower and 

lower terraces down to the present flood plain of Wind River are 

common in all parts of Wind River Basin. Their nearly level surfaces furnish excellent routes for wagon roads and can be followed 

for miles with only occasional interruptions produced by intrenched 

ravines.

As stated above, the highest peaks in the Wind River Range reach 

altitudes well above 13,000 feet. The adjacent* part of the Wind 

River Basin ranges in height from about 5,000 to 6,000 feet. Lander 

stands a little less than 5,400 feet above sea level, and Fort Washakie 

at about the same altitude. The mouths of the canyons of the principal branches of Popo Agie and Little Wind rivers, where these 

streams issue from the mountains, are approximately 6,000 feet above 

sea level, and the fall averages about 100 feet to the mile for the first 

8 miles downstream.

The principal streams issuing from the Wind River Range in the 

district are North and South forks of Little Wind River, North and 

Middle forks of Popo Agie River, and Little Popo Agie River. 

These are all large, swift streams that furnish an abundant supply of 

clear water, which is extensively used for irrigation. There are a 

number of smaller perennial streams, among which are Sage, Trout, 

Baldwin, Squaw, Willow, and Beaver creeks. Others are fair-sized 

brooks in their upper courses and sink into the ground a short distance away from the mountain front. Still others, such as Mill 

Creek, in T. 2 S., R. 2 W., have their sources in large springs that 

issue from limestone strata at the base of the mountains.

The climate of the Wind River region is semiarid, and the annual 

rainfall about 15 inches near Lander although greater than in 

many other parts of Wyoming, is not alone sufficient for the growth 

of crops of hay. Irrigation is therefore generally practiced. The 

North and South forks of Little Wind River and the several branches 

of Popo Agie River furnish a plentiful supply of water, which is 

put to good use along the spacious valley floors of those streams and 

on neighboring bench lands. Alfalfa and other hays, the principal
GEOGRAPHY 5

crops, are used for the winter feed of thousands of cattle, which graze 

on the mountain slopes during the summer. In the higher parts of 

the region snow commonly falls during the later part of September 

and may be accompanied by severe cold, after which there is a month 

or so of mild weather during which the snow melts from the mountain 

slopes up to an altitude of perhaps 9,000 feet.

Lander, the principal town and the county seat of Fremont 

County, had in 1920 a population of 2,133. Hudson and Riverton 

are both prosperous villages, Hudson being the center of a coalmining industry and Eiverton an important shipping and receiving 

point for Wind River Basin. The administrative headquarters for 

the Shoshone Indian Reservation are at Fort Washakie, near the 

center of the reservation, which occupies the area from Wind River 

south to the North Fork of Popo Agie River and from Riverton on 

the east to the vicinity of Circle, some 65 miles farther west.

The mining industry of the region consists chiefly of the production of coal, oil, natural gas, and gold. No attempt has been made 

to mine phosphate rock. Several coal mines have for years been in 

operation at Hudson, and the coal is shipped to different points. 

It is a subbituminous coal and is best suited for domestic use and 

as a steam coal in stationary boilers.

Seepages of oil at several points along the elongated domes near 

Fort Washakie. Lander, and Dallas were noticed by the early settlers? 

and the field has produced more or less oil continuously since 1883, 

when the first well was drilled. In recent years there has been considerable interest in the Pilot Butte and Maverick Springs domes,* 

in the upper part of Wind River Basin, in both of which oil has 

been developed, and in the Derby dome, a short distance southeast 

of Dallas, where some oil has been obtained. The present production from the entire Lander district, embracing the Derby, Dallas, 

Lander, Pilot Butte, and Maverick Springs pools, does not exceed 

several hundred barrels of oil daily.

Gold has been mined in the Atlantic mining district, some 25 

miles southeast of Lander, since early pioneer days, and the production to date is variously estimated at $1,000,000 to $5,000,000. In 

the early history of the district most, of the gold came from placer 

deposits, but later the mining of lode deposits was begun. Mining 

operations have not been pushed vigorously in recent years, but there 

will be a great renewal of activity if transportation facilities are 

improved by the construction of a railroad along Sweetwater Valley.

The Chicago & Northwestern Railway has its terminus at Lander, 

about 6 miles from the phosphate deposits of the adjacent mountain 

front. The line could be extended farther west up Wind River

8 See Collier, A. J., Anticlines near Maverick Springs, Fremont County, Wyo.: U. S 

Geol. Survey Bull. 711, pp. 149-166. 1920.
6 PHOSPHATE IN WIND RIVER MOUNTAINS, WYO.

Basin, but it is highly improbable that a route will ever be sough, 

across the Continental Divide, to the west, which presents an unbroken mountainous front from 9,000 to more than 10,000 feet in 

altitude.

When the Union Pacific Railroad was planned many engineers 

regarded the Sweetwater route across South Pass, at the southeast 

end of the Wind River Mountains, as more favorable than the more 

southerly route that was finally adopted. It is possible that sometime either the Northwestern or the Burlington system will seek an 

entrance to Green River Basin by way of South Pass. With the extension of either of these lines the situation of the southeastern portion of the phosphate field as regards transportation would be improved.

Good wagon roads lead in all directions from Lander. Stages 

and mail leave daily for Fort Washakie and more remote points to 

the west and also for Atlantic, South Pass, and Pinedale. The road 

to Atlantic leads through Dallas, up Little Popo Agie River and 

Red Canyon, and across the bench lands adjoining Twin Creek. All 

the principal streams flowing from the mountains furnish easy natural routes which are followed by roads leading to the numerous 

ranches. At the base of the mountains the valleys suddenly contract to narrow canyons and most of the roads end, but a few continue farther up to give access to timber tracts.

The portion of the Wind River Range opposite Lander is included 

in the Washakie National Forest. Most of the canyon slopes are 

heavily timbered. The mountain front up to an altitude of 7,500 

feet bears little timber, and the long limestone dip slopes are largely 

soil-covered and grassed. In the sheltered ravines thickets of quaking aspen and scattered pine and spruce are common. At higher 

altitudes the pine forest covers most of the surface, being densest 

on the north exposures.

GEOLOGY

STRATIGRAPHY 

PUB-CAMBRIAN ROCKS

The pre-Cambrian rocks of the Wind River Range consist of a 

large variety of metamorphic and igneous rocks, of which no adequate 

study has yet been made. Among the oldest members of the complex are banded gneisses and mica schists into which have been intruded dikes of pegmatite and dikes and stocks of basic igneous 

rock. The structure is of the complex type common to such rock. 

It has been observed that in general the plane of schistosity or 

gneissoid banding trends roughly north, or nearly at right angles to 

the axis of the Wind River Range.
STRATIGEAPHY ;7

 Outcrops of pre-Cambrian rocks form a broad belt of high peaks 

extending the entire length of the Wind River Range. There are 

also small areas along the axis of the Sheep Mountain anticline in 

T. 30 N., R. 97 W. Farther east lie the Granite Mountains, a low 

range consisting of numerous scattered granite hills projecting 

above a plateau of flat-lying Tertiary beds.

Gneissoid granite cut by unaltered granite, which is in turn cut 

by pegmatite dikes, has been observed by Blackwelder in the northern part of the Wind River Range. Farther south dikes of diabase 

cutting granite Avere seen. In the Sweetwater mining, district the 

country rock, a dark slaty .schist, is believed by Knight 4 to be 

Algonkian. It is very ferruginous and has zones of magnetite 

schist. Trap dikes are plentiful, and along and near them are the 

gold-bearing quartz veins that constitute the basis for the mining 

industry in the Sweetwater district.

The metamorphic complex is overlain by an essentially conformable sequence of rocks ranging in age from Middle Cambrian to 

Upper Cretaceous. The Paleozoic strata alone have a thickness of 

nearly 4,000 feet, and the overlying Mesozoic strata as found in the 

Wind River Basin are probably 10,000 feet thick. The oldest of this 

long sequence of sedimentary rocks is the Flathead sandstone, of 

Middle Cambrian age. The Cambrian and younger rocks are essentially unmetamorphosed.

FLATHEAD SANDSTONE

The Flathead sandstone (Middle Cambrian) consists largely of 

gray or brown shaly sandstone and micaceous sandy shale, with 

several beds of brown quartzitic sandstone. As a whole it is a comparatively weak formation, and complete outcrops of it are rare. 

Few fossils have been found in it, and the commonest forms are 

black oboloid brachiopods. The formation averages about 300 feet 

in thickness and over large areas contains one or more members of 

chocolate-brown quartzitic conglomerate. .

GROS VENIRE FORMATION «

The Flathead sandstone grades up into a series of clay shales with 

alternate beds of limestone and calcareous shale, which together 

constitute the Gros Ventre formation (Middle Cambrian). In Bea 

Ogwa Canyon this formation appears to be about 600 feet thick; 

in the Wind River Range it may be slightly less. The shales are

4 Knight, W. C., The Sweetwater mining district, Fremont County, Wyo.: Wyoming 

Univ. Bull., 1901. See also Spencer, A. C., The Atlantic gold district an<? the Nortn 

Larnmle Mountains, Fremont, Converse, and Albany counties, Wyo.: U: S'. Geol. Survey 

Bull. 626, 1916.

6 Blackwelder, Eliot, New geological formations in western Wyoming: Washington 

Acad. Sci. Jour., vol. 8, pp. 417-419. 1918.
8 PHOSPHATE IN WIND EIVER MOUNTAINS, WYO.

grayish to green and range from, distinctly sandy shale near the 

base to highly calcareous shale near the top. The interbedded limestones are generally gray, more or less mottled with olive and ocher 

colors. Many of the beds contain black oolitic granules, and others 

consist of "edgewise" conglomerate. Some of the limestone beds 

contain fragmentary Middle Cambrian trilobites, but on the whole 

fossils are not abundant. Complete exposures of the formation are 

rare, because the shale beds are generally concealed by soil and vegetation, leaving only the more massive limestone beds protruding as 

ledges and reefs.

GALLATIN LIMESTONE

Although limestone predominates in the Gallatin formation 

(Upper Cambrian), there is more or less shale and sandstone in the 

middle portion. In the northwestern part of the Wind River Range 

the terrane is 250 feet thick, but toward the southeast it appears to 

become somewhat thinner. At the base is a massive, finely crystalline 

limestone of dark-gray color clouded with brown. On close examination it is found to be filled with little sepia-brown oolitic 

granules about the size of mustard seed. This lower member is 

20 to 100 feet thick. The middle member is generally thin bedded 

and contains layers of gray calcareous shale and buff sandstone. 

" Edgewise conglomerate" thickly sprinkled with glauconite grains 

is characteristic of this member. The uppermost member is relatively thin bedded and contains a little shale. The rock is dolomitic 

and more or less siliceous, with thin laminae of chert. Some layers 

are richly fossiliferous.

BIGHORN DOLOMITE

The thin-bedded Gallatin limestone is overlain by the Ordovician 

Bighorn dolomite. The lower part is massive, cream-colored to 

nearly white, and of saccharoidal texture. Its weathered surfaces 

are very rough and pitted. Above the massive dolomite are thin beds 

of dolomitic rock which, as exposed in Dinwoody Canyon, have a 

thickness of about 30 feet. Fossils are fairly plentiful in both 

the upper thin-bedded portion and in the massive lower portion, and 

on the evidence they afford the formation has been referred to the 

Ordovician.

At the north end of the Wind River Mountains the Bighorn is 

300 feet thick, and some of the individual massive beds are 25 feet 

thick. Toward the south the formation thins, and in a section in 

the canyon of Middle Fork of Popo Agie River near Lander it is 

163 feet thick. Beneath the dolomite is locally a bed of sandstone 

containing fossils of the large cephalopod Endoceras.
STRATIGRAPHY 9

There is but little record of unconformity at the base of the Bighorn, but at the top the evidence is clearly recorded by solution 

caverns, an undulating contact, and general unconformable relations with the overlying Devonian strata.

DEVONIAN STRATA

In the northern part of the Wind Eiver Kange the Bighorn 

dolomite is separated from the Madison limestone above by a few 

feet of limestone containing Devonian fossils. In Dinwoody Canyon 

strata of this age are only 5 feet thick, but toward the west they 

thicken to several hundred feet in the Teton Kange, where the 

name "Darby formation" has been applied to the beds by Blackwelder.6

MADISON LIMESTONE

Few formations in Wyoming are more easily recognized than the 

Madison limestone (Mississippian). It consists almost entirely of 

dark-gray limestones, in general plentifully fossiliferous. Where 

adequately exposed it produces high cliffs and mountainous ridges. 

At the west end of the Wind Kiver Kange it is nearly 800 feet thick, 

but toward the southeast it gradually thins, being about 500 feet 

thick in the vicinity of Lander and still thinner beyond that town.

The formation consists of alternating thick and thin beds of gray 

limestone with a few layers of brownish-gray dolomite and a small 

amount of calcareous shale. Some of the limestone beds are 20 to 

30 feet thick; others are thin slabs. This variation in thickness gives 

the outcrop in many places the aspect of a series of huge steps. The 

thicker beds are usually rather light gray or lead-colored limestone 

of dense texture. Chert is not characteristic of the Madison but 

commonly appears in black or dark-gray nodules.

AMSDEN FORMATION

The Amsden, which is probably all late Mississippian in this area, 

is a relatively weak member of the Paleozoic sequence that generally 

occupies slopes and hollows between the cliffs and ridges of the 

underlying Madison limestone and the overlying Tensleep sandstone. 

Exposures of the softer beds are not common, and complete sections 

of the formation can be observed only in the most favorable places. 

Throughout western Wyoming the formation is readily divisible 

into a lower sandstone member and an upper shale and dolomite 

member.

The lower member is a cream-colored calcareous sandstone averaging 30 to 50 feet in thickness but apparently only 20 feet thick 

near Lander. Cross-bedding is characteristic of the sandstone.

 Blackwelder, Eliot, New geological formations in western, Wyoming: Washington 

Acafl. Sci. Jour., vol. 8, pp. 417-426, 1918.
10 PHOSPHATE IN WIND EIVER MOUNTAINS, WYO.

The lower sandstone member is separated from the somewhat 

similar Tensleep sandstone above by 50 to To feet of alternating 

shale, sandstone, and dolomite. Near the base of this sequence there 

is generally 10 to 15 feet of dark-red marly limestone or shale containing small nodules of hematite. Fossils are fairly plentiful in 

the Amsden formation, but in most localities they are too poorly 

preserved to be clearly identifiable. In this area the beds all appear 

to be of late Mississippian age, to judge from fossils collected by 

Branson " in the Little Popo Agie region and at Bull Lake, a short 

distance to the north, but farther east in Wyoming the Amsden has 

yielded Pennsylvanian fossils and has been regarded as chiefly of 

Pennsylvanian age.

TENSLEEPSANDSTONE

The Tensleep sandstone (Pennsylvanian) is a massive resistant 

formation which reveals itself in hogback ridges and cliffs. Its 

thickness ranges from 300 to 450 feet and is greatest opposite Fort 

Washakie, the formation thinning both to the northwest and the 

southeast. It consists almost entirely of fine-grained friable white 

and buff sandstone. Many of the layers are distinctly calcareous, 

but others have been cemented into quartzite. Nearly all the strata 

are regularly cross-bedded, and the laminae are in most places inclined toward the southwest. Fossils are rare, but a few marine 

mollusks have been found in calcareous beds in the Big Horn Mountains.

EMBAB FORMATION OF BARTON

Strata 300 to 500 feet thick lying between the Tensleep sandstone 

and Chugwater red beds in west-central Wyoming were designated 

the Embar formation by Darton.8 The strata contain phosphate rock 

.in the Wind River and Owl Creek mountains. In Wind Eiver Basin, where they lie under cover, they are a source of oil and gas. 

Blackwelder,9 as a result of studies of the Wind River Mountains, 

found it desirable to divide the Embar into two formations, because the rocks included are so different in character and cover so 

large a geologic range. To the upper shaly part, of Triassic age, he 

applied the name Dinwoody formation, from exposures in Din woody 

Canyon, in the Wind River Mountains; and to the lower part, consisting largely of limestone and calcareous shales, he applied the 

name Park City formation, on account of their equivalence to beds of

7 Branson, E. B., and Greger, D. K., Amsden formation of the east slope of the Wind 

Kiver Mountains of Wyoming and its fauna: Geol. Soc. America Bull., vol. 29, pp. 307- 

326, 1918.

8 Darton, N. H., Geology of the Bighorn Mountains : U. S. Geol. Survey Prof. Paper 51. 

p. 35, 1906.

8 Blackwelder, Eliot, New geological formations in western Wyoming: Washington 

Acad. Sci. Jour., vol. 8, pp. 417-426, 1918.
U. S. GEOLOGICAL SURVEY BULLETIN 764 PLATE I

A. VIEW NORTHEASTWARD ACROSS WIND RIVER BASIN FROM SLOPE OF 

WIND RIVER RANGE IN T. 5 N., R. 6 W.

B. VIEW EASTWARD TOWARD HEAD OF RED CREEK CANYON IN T. 31 N.,

R. 99 W.
U. S. GEOLOGICAL SURVEY

A. EXPOSURES OF PHOSPHORIA FORMATION (X) 

IN CANYON OF SOUTH FORK OF POPO AGIE 

RIVER

B. TYPICA

ING UPPOF POPO 
STRATIGRAPHY 11

that name in northeastern Utah. Later studies, by several workers, 

have proved that the part of the Embar beneath the Dinwoody formation corresponds to only the upper or Phosphoria part of the Park 

City formation of Utah, and the United States Geological Survey 

noAv designates this lower part of the Embar of, western Wyoming 

as Phosphoria formation, instead of Park City formation.

PHOSPHORIA FORMATION

The Phosphoria, of Permian age, is the great phosphate-bearing 

formation of the Rocky Mountain region and contains the valuable 

beds mined on a commercial scale in western Wyoming, southeastern 

Idaho, and northward across Yellowstone Park in southern Montana. It corresponds to the upper portion of the Park City formation of northeastern Utah.

In the Wind River Mountains the Phosphoria formation is 200 to 

300 feet thick. The upper part may be divided into three rather 

distinct members, which are recognizable not only throughout the 

Wind River Range but as far west as Idaho. For reasons set forth 

below these members are appropriately called the upper bryozoanbearing limestone, the phosphatic shale, and the lower bryozoanbearing limestone. The underlying beds are so variable that subdivisions which might be made for one section would not apply well 

in adjacent sections. Below is a representative section of the Phosphoria formation, measured on South Fork of Little Wind River:

Section of Phosphoria formation on South Fork of Little Wind River

Upper bryozoan-bearing limestone: Ft. in. 

' Limestone, chalky in upper portion, clolomitic and

cherty, grayish below____________________ 12

Limestone, brownish gray, crystalline, fossiliferous; 

Lcioclema, Fenestella, Spiriferina pulchra, Derbya, 

and small crinoid segments plentiful_________ 22 

Chert, nodular, in bluish-gray shaly matrix_______ 14 

Shale, siliceous, bluish gray and cherty near top, drab

to sepia-brown, with phosphate bands, in lower part___ 37 8 

Upper phosphate bed:

Phosphate, dark, oolitic, sandy; Pugnax only fossil

recognized (tricalcium phosphate, 41.14 per cent)__ 1 4 

Phosphate, sandy; Productus nevadensis and Pugnax

common (tricalcium phosphate, 43.74 per cent) 1 6 

Lower bryozoan-bearing limestone:

Limestone, brownish gray, thin bedded; Productus 

nevadensis and Spirifer aff. 8. cameratus plentiful. 

In the lower portion are abundant specimens of 

Chonetes aff. C. geinitsianus- ____________ 12

Limestone, massive, yellowish brown, crystalline; 

many fossils, Leioclema especially abundant 31
12 PHOSPHATE IN WIND RIVER MOUNTAINS, WYO.

Ft. in.

Limestone, dolomitic, interbedded with laminated chert

and sandy shale_____________________ 84 

Limestone, gray, coarsely crystalline, massive; abundant 

'' molds of diminutive pelecypods and gastropods____ 31 

i Lower phosphate bed:

Limestone, phosphatic, gray, with dark spots; Lingulidiscina utahensis present_____________ 1 

Phosphate rock, calcareous, dark, granular (tricalcium phosphate, 36.51 per cent)___________ 6 

Limestone, phosphatic, dense textured, dark; a fossil,

probably Composita, present_____________ 10 

Phosphate rock, calcareous; green granules of glauconite (?) abundant; phosphatic shells of Lingulidiscina 'abound (tricalcium phosphate, 48.13 per 

cent) - 1 

Phosphate rock, dark, calcareous; few traces of fossils

(tricalcium phosphate, 39.92 per cent)_______ 8 

Limestone, granular, thick bedded, having small calcite

vugs; granules of glauconite (?) present________ 12 

Limestone and dolomite, argillaceous, gray, with cherty

layers and localized green stains-___ _______ 31 

Chert, white and gray, laminated. ___ ______ 7

Limestone, buff, dolomitic, resting on Tensleep sandstone 4

Fossils have been found in each of the four principal divisions of 

the Phosphoria formation. The upper bryozoan-bearing limestone 

has abundant large specimens of the bryozoan Leioclema and the 

brachiopods Derby a sp. and /Spiriferina pulchra. In the phosphatic 

shale underlying this limestone fossils are rare, but the following 

have been identified by G. H. Girty from material collected in the 

principal bed of phosphate at the base of the shale:

Nucula? sp. 

Pleurotomaria? sp. 

Productus nevadensis. 

Productus subhorridus.

The lower bryozoan-bearing limestone contains abundant fossils 

everywhere, the most prominent being Leioclema and /Spiriferina 

pulchra. Chonetes aff. C. geinitzianus is also plentiful in a few 

places.

The upper bryozoan-bearing limestone is variable in detail but is a 

prominent, easily recognized member throughout the district. Along 

the northeast slope of the Wind River Range it consists generally of 

massive gray to cream-colored limestone 30 to 60 feet thick, underlain 

by greenish nodular chert in a matrix of shale. The rock becomes 

more dolomitic toward the south end of the range, and the fossils are 

not so well preserved. It is prominent as a controlling factor in the 

topography of both the Wind River and the Owl Creek mountains 

and produces long faceted dip slopes along the mountain front.
STRATIGRAPHY 13

The phosphatic shale is probably the most distinctive member of 

the Phosphoria formation. On the north slope of the Wind River 

Range it consists of sepia-brown to nearly black shale 20 to 40 feet 

thick, more or less cherty in the upper portion. It is for thei most 

part notably fissile and has bands of limestone and oolitic phosphate 

and at the base the upper or Productus-bearing phosphate bed.

'The lower bryozoan-bearing limestone lies beneath the phosphatic 

shales and is a little above the middle of the formation. It is grayish 

to brown and becomes distinctly darker and more phosphatic toward 

the top. In addition to Bryozoa it commonly contains many comminuted fossil fragments, large brachiopods, green granules possibly 

of glauconite, and scattered foraminiferal shells.

The lowest division of the Phosphoria, although more variable than 

the other members, generally consists of two shaly zones, each underlain by beds of dolomite, sandstone, and chert. The shales are yellowish to greenish, and the lower shale zone especially contains much 

chert in the form of thin greenish laminae and locally large geodes 

of calcite. About 50 feet above the Tensleep sandstone is a massive 

gray limestone ledge, beneath which is a phosphate bed filled with 

the disk-shaped shells of Lingulidiscina utahensis (also known as 

Orbiculoidea utahensis). This bed is recognizable throughout the 

Wind River Range and at a number of places has been found to contain fossil fish, collections of which are described by Branson.10

DINWOODY FORMATION

The highly fossiliferous Phosphoria strata are overlain by the 

Din woody formation (Triassic), a series of shale and shaly limestone 

 \\hich yield few satisfactory fossils but nevertheless have characteristics so distinctive as to be easily recognized wherever they are exposed. Typically the Dinwoody formation consists of greenish-gray 

shale alternating with thin slabs of dense calcareous sandstone or 

sandy limestone of greenish-gray color that weathers to a deep brown. 

Near the top the beds are more argillaceous and locally contain more 

or less gypsum. The thickness is 150 to 200 feet in the northwestern 

part of the Wind River Mountains and gradually diminishes eastward, being 70 feet at Bea Ogwa Canyon and 30 feet at Sheep Mountain, south of Lander.

CHTTGWATEK FORMATION

No formation in the region is so conspicuous and so easily recognized as the Triassic Chugwater red beds. With a fairly uniform 

thickness of 1,200 to 1,450 feet they skirt the northeast slope of the

10 Branson, E. B., The lower Embar of Wyoming and Its fauna: Jour. Geology, vol. 24, 

pp. 638-664, 1916.
14 PHOSPHATE IN WIND RIVER MOUNTAINS, WYO.

Wind Eiver Range and the Rattlesnake Mountains, to the east 

The same formation extends around the Owl Creek uplift, whereit is only a little thinner than in the Wind River Range. At first 

glance the Chugwater appears to consist of a monotonous sequence 

of shaly red sandstones and sandy shales, but more detailed examination shows that there is much variety and individuality in detail. 

Like red beds in general, the Chugwater is sparingly fossiliferous, 

though bits of silicified wood, vertebrate bones, and mollusks havebeen found in it. In the lower third of the formation shale predominates and exposures are much less common than in the upper beds. 

The shales are slightly micaceous and contain a large admixture of 

very fine sand which imparts to the rock an earthy texture. Theprevailing colors are brick-red to chocolate, with a few thin beds 

and blotches of greenish gray. The red shales grade upward into a 

somewhat similar sequence about 400 feet thick, in which sandstonepredominates and which is more prominently exposed. There are 

generally one or two beds of hard gray nonfossiliferous limestone. 

The middle sandstone is overlain by a weaker zone of shale, clay,. 

and sandstone with thin layers of limestone. Above this shaly portion is about 150 feet of orange-colored massive sandstone, the most 

resistant member of the formation. The highest member is weak 

shale, generally not exposed. It has beds of massive snow-white 

gypsum, 25 to 50 feet thick or locally even thicker.

SUNDANCE FORMATION

The Chugwater red beds are overlain by the gray or greenish 

shale beds of the Sundance formation (Upper Jurassic) . The lower 

half of this formation contains many beds of limestone, which grade 

upward into a calcareous clay with thin beds of sandy limestone. At 

many horizons are found shells of Gryphaea calceola and Belemnites 

densus. At the top of the formation is sandstone which has no fossils 

and might well be included in the Morrison formation. The thickness of the Sundance is 200 to 300 feet; it is greatest at the west end 

of the region and decreases toward the east.

Over the fossiliferous Jurassic beds and upper sandstone member 

is a weak series of soft clay shales and interbedded sandstones with 

local beds of fresh- water limestone representing the Morrison formation (Cretaceous?) and overlying Lower Cretaceous (?) rocks. 

Gray and lavender colors predominate, but there are many broad 

and narrow stripes of maroon, pink, olive, green, purple, russet, and 

white. Few distinctive fossils have been found in these rocks in 

the Lander region. The thickness is 300 to 400 feet.
STRATIGRAPHY 

CRETACEOUS STRATA

15

The strata of known Cretaceous age exposed in the Wind Elver 

Basin form a sequence more than 8,000 feet thick and include valuable beds of coal and sandstones that yield oil arid gas. Below 

is a table showing the classification of the strata as described by 

Woodruff and Winchester.11

 Geologic relation of the Upper Cretaceous formations in the Wind River region

System

Tertiary.

 Cretaceous.

Series

Eocene.

Upper Cretaceous.

Group

Montana

Colorado

Formation

Wind River t.ormation.

Fort Union formation.

Mesaverde formation.

Mancos shale.

Character

Banded sandy shale, sandstone, and 

conglomerate.

Sandstone and sandy shale, with beds 

of coal.

Tan-colored sandy shale and a few 

sandstone lenses, with beds of coal.

Slightly ferruginous sandstone and a 

small amount of sandy shale with 

beds of coal.

Thick beds of tan-colored sandy shale , 

shaly sandstone, and local lenses of 

massive sandstone. Only the upper 

part exposed in the coal fields.

In the eastern part of the Wind River Basin is a prominent sandstone with associated shale 150 to 200 feet thick, overlying the varie- 

.gated Morrison shales. This includes the Dakota sandstone, the 

basal formation of the Upper Cretaceous. Westward the sandstone 

disappears, and the horizon is occupied by dark olive-colored shales.

Over the Dakota sandstone is a thick sequence of marine shales 

with a few beds of sandstone. Woodruff 12 describes this formation 

as the M'ancos shale and states that the thickness is more than 6,000 

feet. In general the formation is characterized by dull-gray to 

.sooty-black shales which contain cycloid fish scales. In the upper 

part of the black-shale zone are beds of a peculiar yellow clay known 

as bentonite. The formation contains a few thin coal beds of little 

economic importance. The valuable coal beds of this part of Wyoming lie in the Mesaverde formation, which overlies the Mancos shale.

TERTIARY STRATA

The Cretaceous and older rocks are overlain discordantly by the 

Tertiary formations, which aggregate several thousand feet in thickness. The lower part, usually designated the Wind River formation, consists largely of striped gray, pink, and chocolate-colored 

 clays of Eocene age, with many beds of soft, earthy gray sandstone

11 Winchester, D. E., and Woodruff, E. G., Coal fields of the Wind River region, Fremont and Natroua counties, Wyo.: U. S. Geol. Survey Bull. 471, pp. 516-564, 1912.

12 Woodruff, E. G., The Lander oil field, Fremont County, Wyo.: U. S. Geol. SVirvey 

Bull. 452, pp. 20-22, 1911.
16 PHOSPHATE IN WIND RIVEB MOUNTAINS, WYO.

and at the base conglomerates of varied character. The outcrops of 

the formation have been eroded into badlands around the headwaters of the valleys.

At the west end of the Owl Creek Mountains and in the Absaroka 

Range the striped clays pass upward by insensible gradations into 

greenish and purplish clays which contain more or less volcanic 

ash and locally inclose pieces of silicified wood and plant leaves. At 

still higher horizons the proportion of volcanic material increases 

to predominance, producing tuffaceous sandstone and shale, with 

beds of coarse structureless agglomerate that form the rugged castellated peaks of the Absaroka Range. The 'age of the volcanic deposits has never been satisfactorily determined but appears to be 

either late Eocene or Oligocene.

Near the south end of the Wind River Range the earliest Tertiary 

beds exposed also consist of striped greenish and pink clays, 'apparently the same as the Wind River beds to the north. These clays are 

overlain by a varied series of grayish beds that form the greater 

part of the plateau in the Sweetwater region. This series includes 

marly limestone, greenish-gray clay, friable arkosic sandstone, 

and gravel, with a few chalky beds consisting in part of volcanic 

ash. All have been faulted and folded locally and constitute a complex series concerning which little is known. The work of Sinclair 

and Granger 18 indicates that both the Eocene and Oligocene are 

represented.

GLACIAL DRIFT (PLEISTOCENE)

Most of the large canyons of the Wind River Range contained 

glacial tongues which left prominent moraines along the foothills. 

Bouldery deposits of this sort are notably prominent at the canyon 

mouths of North and South forks of Little Wind River and North 

and Middle forks of Popo> Agie River. There are two sets of moraines of quite different ages, thei earlier having been deeply intrenched before the deposition of the younger material.

TEBRACE GRAVEL

Gravel-covered table-lands occur at various altitudes along the 

Wind River Mountains, from about that of the valley of Wind 

River up to "more than 8,000 feet. The most conspicuous and best 

preserved of the high-level gravel deposits occur at altitudes of 7,200 

to 7,700 feet. One of the most prominent is Table Mountain, a few 

miles south of Lander, which consists of a flat-topped table of beveled 

Chugwater red beds capped by about 200 feet of coarse, roughly 

stratified gravel. The slope is estimated at about 40 feet to the mile

18 Sinclair, W. J., and Granger, Walter, Eocene and Oligocene of the Wind River and 

Bighorn basins: Am. Mus. Nat Hist. Bull., vol. 30, pp. 83-117, 1911.
STEUCTTTEE 17

away from the mountain. The Tensleep sandstone ridge to the west 

is also beveled to a level corresponding to that of Table Mountain, 

as if a rather broad valley had here opened out from the range. 

Similar deposits of coarse gravel are found northward along the 

mountain front for many miles, a conspicuous example being on the 

north side of North Fork of Little Wind River at an altitude of 

7,500 to 7,700 feet. The significance of these benches and other 

topographic features of the region is described by Blackwelder.14

STRUCTURE'

The structure of the Wind River Range is for the most part very 

simple, the mountain being a broad eroded anticline whose slopes are 

made up of alternating hard and soft beds that have an intimate 

relation to the topography. Throughout most of its extent the northeast mountain slope is remarkedly free from faults, and only a few 

monoclinal folds vary the usual inclination of the beds toward the 

northeast. Parallel to the main mountain axis is a line of elongated 

domes extending from the upper part of the Wind River Basin 

southeastward past Fort Washakie and Lander and thence beyond 

Sweetwater River for an unknown distance. One of these domes 

in T. 30 N., R. 97 W., is a prominent topographic feature known as 

Sheep Mountain.

The only faults of consequence in the area cut the beds of Sheep 

Mountain and the adjacent portion of the mountains to the southwest. There has been a small amount of overthrust faulting parallel 

to the axis of the Sheep Mountain anticline, but by far the niost 

pronounced fault line in the area extends at right angles to the axis, 

apparently being continuous with the fault in the southern part of 

T. 30 N., R. 98 W., which has produced an offset of the beds on the 

south side of about 3 miles to the east. From Sheep Mountain this 

fault line is marked by a prominent escarpment extending northeastward for about 4 miles, to the region where the Tertiary tablelands cover the older strata.

TOWNSHIP DESCRIPTIONS

On the northeast slope of the Wind River Range phosphate occurs 

in the Phosphoria formation at two principal horizons one a little 

above the middle and the other 40 to 50 feet above the base. Their 

stratigraphic positions are shown in the section measured on South 

Fork of Little Wind River, which is given in detail on pages 11-12. 

The character of the phosphate beds as found in outcrops along the 

mountain front in each township is described below, the discussion 

beginning with the township on the northwest opposite Fort

" Blackwelder, Eliot, Post-Cretaceous history of the mountains of central Wyoming: 

Jour. Geology, vol. 23, pp. 97-117, 183-217, 307-340, 1916.
18 PHOSPHATE IN WIND RIVER MOUNTAINS, WYO.

Washakie. Sections of the beds at each sampling point are shown 

on the map (PI. III).

T. 1 N., E. 3 W.

T. 1 N., K. 3 W. Wind River meridian, is within the Shoshone 

Indian Reservation, about 8 miles west of Fort Washakie. Topographically the area is about equally divided between the rugged 

foothills on the southwest and the relatively flat edge of Wind River 

Basin on the northeast. The principal drainage line is North Fork 

of Little Wind River, which rises in the high mountains to the west. 

The rugged western portion of the township has not been subdivided 

into sections.

There are two small ranches among the red hills, along the mountain base. One of these, on South Fork of Sage Creek, obtains water 

for irrigation from that stream. The other, which occupies parts of 

sees. 10 and 11, utilizes water that is diverted from St. Lawrence 

Creek, a branch of North Fork of Little Wind River.

The outcrop of the Phosphoria beds extends diagonally across the 

central part of the township and dips 15°-40° NE. In the belt of 

Tensleep sandstone and underlying formations closely paralleling the 

Phosphoria on the southwest the beds are more steeply tilted, the dip 

being 50° to 70°; in the Chugwater red beds on the northeast the dip 

flattens to a maximum of about 15°. The valley of North Fork of 

Little Wind River and the adjacent hills are littered with glacial 

drift, which covers the bedrock, producing an extremely bouldery 

surface that is unsuited for agriculture. On the north side of the 

valley and about 1,200 feet higher is a gravel-covered mesa 3 miles 

long whose surface slopes gently basinward. Its altitude' ranges 

from about 7,500 to 7,700 feet.

In this township the Phosphoria formation has a thickness of about 

290 feet and contains the two usual phosphate beds, one 55 feet and 

the other 200 feet above the Tensleep sandstone. The lower bed was 

not seen in the township, and its presence is inferred from the fact 

that it is present in fair development on South Fork of Little Wind 

River a few miles to the south.

The upper* bed was sampled at two localities, in the SW. ^4 sec. 4 

and the NW. % sec. 21. At both places it is a dark-brown oolitic 

sandy rock, containing fossils. In sec. 4 the thickness is 2% feet 

and the tricalcium phosphate content averages 41.2 per cent. In sec. 

21 the thickness is 2 feet and the tricalcium phosphate content 46.1 

per cent. The bed is overlain by 10 feet or so of fissile shale, dark in 

the lower portion and gray above, with one or more thin layers of 

oolitic phosphate toward the top. Beneath the principal bed is fossiliferous gray limestone.
U. S. GEOLOGICAL SURVEY

1

fe

 Morrison formation ^ CRET(?) 

Sundance formation

Chugwater formation 

(red beds) 1,000-1,400 feet

Dinwoody formation"] ® J 

Phosphoria formationV^ 

300-400 feet j|o

Tensleep sandstone 

250-450 feet

Amsden formation

Madison limestone

Devonian limestone 

Bighorn dolomite 

Gallatin limestone

Gros Ventre shale 

Flathead sandstone

GENERALIZED CROSS SECTION

OF THE 

WIND RIVER MOUNTAIN FRONT

^dstone

Limestone

Granite

BULLETIN 764. PLATE III

1091' 4-3 c

;5/.' />/ v-'

Structure cent ours on base ~ ~| * 

of Chugwat-;r formation Axis of anticline 

Interval l.OiK) feet

Datum, sea !e\-el - -f - 

Axis of syncline

Contours showing depth of upper 

phosphate bed below surface

Percentage of tricalcium phosphate is 

shown at left of section; at right is 

thickness in feet and inches

Fault 

-< '

Strike and dip of rocks

Contour lines 

Pre-Embar Interval 100 feet formations

GEOLOGIC MAP OF NORTHEAST SLOPE OF WIND RIVER MOUNTAINS, IN THE VICINITY OF LANDER, WYOMING

1012345678 

Scale iSTooo

Miles
TOWNSHIP DESCRIPTIONS 19 

T. 1 S., US. 2 AND 3 W.

All of T. 1 S., R. 3 W., is mountainous, and only the northeastern 

part has been subdivided into sections. The Phosphoria formation is 

present only in sees. 1, 2, 12, and 13, and the outcrop is in large part 

covered by glacial drift. Few exposures of the phosphate beds were 

found.

In the adjoining township on the east (T. 1 S., R. 2 W.) the 

Phosphoria crops out in a broad belt 1 to 2 miles wide with dip 

slopes inclined northeastward at angles of 10° to 15°. South Fork 

of Little Wind River, a large stream, flows eastward through the 

township in an irregular course. The valley floor is greatly littered 

with glacial drift, which spreads in a fanlike bouldery deposit over 

the low country at the canyon mouth, rendering a large area unfit 

for cultivation. Glacial drift also covers parts of sees. 5, 6, 7, and

8. The two branches of Trout Creek are bordered by arable land, 

some of which is under cultivation.

The Phosphoria and underlying formations are remarkably well 

exposed in the canyon walls of South Fork of Little Wind River, 

where the rocky valley has been scraped bare and furrowed by the 

grinding action of the valley glacier. In fact, the scouring action in 

the upper canyon has left bare rock which furnishes but little opportunity for the forest to obtain a foothold. A detailed measurement of the Phosphoria strata as found on the north side of the 

valley in sec. 17 is given on pages 11-12. The thickness at that noint 

is about 285 feet, and that of the underlying Tensleep sandstone 

480 feet.

Both the upper and lower phosphate beds are recorded in the section measured on South Fork of Little Wind River. The upper 

bed was also sampled at three additional localities in sees. 21 and 35.

The lower bed is about 145 feet below the upper one and 54 feet 

above the Tensleep sandstone. It consists of dark-gray granular 

rock with shells of the fossil Lingulidiscina and greenish specks of 

a mineral that is possibly glauconite. The bed, including a 10-inch 

layer of dark-gray limestone, has a thickness of 3 feet, and the 

lower richest portion, 20 inches thick, averages 44.8 per cent of 

tricalcium phosphate. It is evident that this bed varies greatly in 

thickness from place to place, for in sec. 2 of the adjoining township 

to the south it is only 7 inches thick.

The upper phosphate bed ranges from 27 to 34 inches in thickness 

and contains from 30.3 to 42.5 per cent of tricalcium phosphate; it 

is leanest in the southeastern part of the township. A sample from a 

layer 17 inches thick, representing the richest portion of a 33-inch 

bed in sec. 21, gave on analysis 51.7 per cent of tricalcium phosphate. 

The upper bed is underlain by the usual gray fossiliferous limestone, 

which is also leanly phosphatic.
20

T. 2 S., US. 1 AND 2 W.

The Phosphoria beds extend diagonally across the northeast corner 

of T. 2 S., K. 2 W., and the southwest corner of T. 2 S., R. 1 W,,' 

forming a belt about 1 mile wide. They dip 12°-15° NE. The dip 

slope formed by the upper bryozoan-bearing limestone is deeply 

notched at intervals of about half a mile by sharp ravines occupied 

by small intermittent streams of water, which unite to form Mill 

Creek and Soral Creek. Along the mountain base are numerous 

springs, which to a large extent supply what little water appears in 

those streams.

Practically all of T. 2 S., R. 2 W., is mountainous and suitable only 

for grazing. Much of T. 2 S., R. 1 W., is only moderately rough, 

and along and near North Fork of Popo Agie River there are large 

tracts of irrigable land. Parts of sees. 20 and 21 are covered with 

glacial drift that is too rocky for cultivation.

The following stratigraphic section, measured by A. R. Schultz, 

represents the Phosphoria and Dinwoody formations as found on 

South Fork of Trout Creek in sec. 2, T. 2 S., R. 2 W. It is noteworthy that the lower phosphate bed, which in the township to the 

north is 3 feet thick, is only 7 inches thick here. It resembles the bed 

as found elsewhere, however, in that it contains an abundance of 

L ingulidiscina.

Geologic section in sec. 2, T. 2 S., R. 2 W.

Chugwater red beds, unmeasured.

Dinwoody formation: Ft. in. 

Shale, drab_________________________ 27 6 

Sandstone, calcareous, flaggy, gray, weathering to

deep brown. Fossils mostly obscure pelecypods__ 52 

Phosphoria formation:

" Limestone," siliceous, dark-gray slaglike beds,

coated with black lichens _ __ __ ___ 6 2 

Limestone, gray, massive, fossiliferous- 34 

Shale, calcareous, not well exposed__________ 44 

Shale, drab_________________:_____ 6 

Phosphate, calcareous (36 per cent of tricalcium

phosphate) ____ 1 2

Shale, dark drab _ _ ______ 1 7

Phosphate, upper or ProdMc^s-bearing bed (39.1 per

cent of tricalcium phosphate)___:_________ 2 7 

Limestone, fossiliferous, upper third phosphatic_ 3 5 

Interval mostly shaly limestone with a few massive

ledges__________________________ 122

Limestone, massive, fossiliferous_____ ________ 6 11

Limestone, shaly__ _ _____ 5 

Shale, bluish______________________ 1 11
TOWNSHIP DESCRIPTIONS 21

Phosphoria formation Continued. Ft. in. 

Phosphate, lower or LinguUdiscwa-besiring bed (46.2

per cent of tricalcium phosphate)__________ 7 

Shale_____________________________ 4 

Limestone, fossiliferous, phosphatic___________ 1 4 

Limestone, mostly covered to top of Tensleep sandstone _________________________ 34

The upper phosphate bed consists of two parts a lower one 31 to 

34 inches thick separated from an upper thinner layer by 15 to 19 

inches of shale. In the exposures along North Fork of Popo Agie 

Kiver sampled by Blackwelder the dividing shale band appears to 

be lacking and there is a solid bed of phosphate 4^/2 feet thick, containing 42.4 per cent of tricalcium phosphate. The phosphate bed 

is therefore more valuable at this point than anywhere to the northwest in the Wind Kiver Range. Sections of the beds where sampled

in T. 2 S., Rs. 1 and 2 W., are shown on the map (PI. Ill).

T. 33 N., R. 101 W.

All but about 3 square miles in the northeastern part of T. 33 N., 

R. 101 TT. sixth principal meridian, is mountainous. Limestone beds 

of the Phosphoria formation outcropping in a belt 1 to 2 miles wide 

and dipping 10°-13° NE. produce the usual faceted dip slopes along 

the mountain front. Glacial drift covers a small area within and 

along the border of North Fork of Popo Agie Eiver, and an outwash 

deposit of terrace gravel at an altitude of about 7,200 feet covers 

parts of sees. 13, 14, and 23. Mexican Creek and Baldwin Creek, 

both fair-sized permanent streams, occupy sharp V-shaped canyons, 

in the walls of which are excellent exposures of the rocks.

Complete exposures of the upper and lower phosphate beds were 

found along an irrigation ditch on the south side of North Fork of 

Popo Agie River in sec. 2, about 250 feet above the valley. The 

ditch extends southeastward along the base of the mountain, and 

where it crosses Mexican Creek the upper phosphate bed is again 

perfectly exposed.

The upper bed on the south side of Popo Agie Vallej^, as shown 

in the section on the map (PI. Ill), consists of 41 inches of dark 

granular phosphate rock, fossiliferous in the lower part and averaging 40.6 per cent of tricalcium phosphate. Above this bed is 12 

inches of clay shale, overlain by another layer of phosphate rock 8l/2 

inches thick. The changeable character of the bed is illustrated by 

the fact that where sampled by Blackwelder half a mile to the north, 

across the valley, it is 54 inches thick and yields on analysis 42.4 per 

cent of tricalcium phosphate. On Mexican Creek the upper bed is 

57 inches thick and contains a thin layer of limestone in the upper 

part but no shale. The analyses of the several parts of this bed
22 PHOSPHATE IN WIND EIVEE, MOUNTAINS, WYO.

give an average yield of 34.8 per cent of tricalcium phosphate. 

following section illustrates the sequence of strata associated with 

the upper phosphate bed on Mexican Creek:

Section measured on Mexican Creek

Dinwoody formation: Ft. iu.

Limestone, sandy, thin bedded____________ 30 

Phosphoria formation:

Limestone, dolomitic, thin bedded, weathering to

slaglike siliceous slabs covered with black

lichens__________________________ 5 

Limestone, even bedded; white; contains Derbya

and Leioclema _________________________________ 22

Chert, nodular, in shaly matrix grading upward

into cherty gray glauconitic limestone; Bryozoa

plentiful_________________________ 8 

Shale, dark, calcareous, with lenses of limestone

in upper portion____________________ 45 

Phosphate, with shaly laminae (30.4 per cent of

tricalcium phosphate) ______________ 1 2% 

Limestone, phosphatic (8.7 per cent of tricalcium

phosphate)_______________________ 4 

Phosphate in large and small black granules (40.8

per cent of tricalcium phosphate)_______ 1 10% 

Phosphate, fine grained, calcareous; contains Productus, Spirif er aff. S. cameratus, Spirif erina

pulchra (36.9 per cent of tricalcium phosphate) 1 4 

Limestone, glauconitic, slightly phosphatic; fossils

plentiful; unmeasured.

The lower phosphate bed was seen at one point in the township 

along the irrigation ditch in sec. 2. It lies approximately 145 feet 

below the upper bed and is 18 inches thick. A sample yielded on 

analysis 52.6 per cent of tricalcium phosphate.

T. 33 N., B. 100 W.

The dip slopes of Phosphoria limestone extend across the southwest corner of T. 33 N., R. 100 W. To the east are numerous hogback ridges of the Chugwater and higher strata. In sec. 7 is an 

isolated hill about 7,000 feet in altitude, capped by coarse gravel. 

It lies opposite a deposit of gravel at a corresponding altitude in 

sec. 14 of the adjoining township to the west. Much of this township is capable of cultivation and has been brought under irrigation 

with water from North and Middle forks of Popo Agie River and ' 

Baldwin and Squaw creeks, which flow through the central portion.

In the numerous sharp ravines along the mountain front are good 

exposures of the Phosphoria formation and its two phosphate beds. 

The lower bed, which is a little less than 3 feet thick, is the more 

valuable, containing nearly 60 per cent of tricalcium phosphate;
TOWNSHIP DESCRIPTIONS 23

the upper bed, though slightly more than 3 feet thick, contains at 

best only 41 per cent of tricalcium phosphate. The results of 

measurement and sampling of the upper bed on Baldwin Creek and 

Squaw Creek are shown on the map. A complete section of the 

Dinwoody and Phosphoria beds as found on Baldwin Creek is given 

below.

Section on Baldwin Creek in the SW. % sec. 18, T. S3 N., R. 100 W.

Dinwoody formation : Ft. in.

Limestone and calcareous shale, laminated, weathered

deep brown ; upper portion increasingly shaly 56 

Phosphoria formation:

Limestone, gray to drab; lower part massive; upper 

portion weathers like slaking lime; fossils plentiful 

in lower part______ ___________________ 35

Limestone, bluish drab to gray; weathered rocks resemble pebble-dash surface; somewhat cherty 32

Phosphate, oolitic (18.5 per cent of tricalcium phosphate) __ _ 6

Shale, bluish drab, fissile___________ _____ 24

Phosphate 4

Shale, compact, bluish, phosphatic______________ 5

Phosphate___________ _________ 3 3 

(Sample of above three beds gives 41.1 per cent of 

tricalcium phosphate.)

Limestone, gray, shaly, forming prominent ledge 

beneath phosphate; lower part of interval not well 

exposed _ _____ __ ________ 118

Phosphate, LingiMdiscina horizon, glauconitic (57.9 

per cent of tricalcium phosphate)_________ 2 9

Limestone and covered__________________ 33 

Tensleep sandstone, unmeasured.

T. 32 N., R. 100 W.

The southwest half of T. 32 N., R. 100 W., is a part of the Wind 

River Mountain slope, the lower portion of which is faced with the 

upper bryozoan-bearing limestone of the Phosphoria formation, 

clipping 8°-12° NE. Table Mountain, a prominent topographic 

feature set out from the main mountain front, is a flat-topped gravelcovered mesa 7,100 to 7,200 feet in altitude, covering about 3 square 

miles. The gravel cap, which is made up of very coarse, rudely 

stratified material, has a thickness of about 200 feet and rests upon 

beveled Mesozoic beds. Opposite Table Mountain is a corresponding nearly level plain extending far into the mountains. It is one of 

the ancient outwash channels whose deposits occur at so many places 

along the mountain front at altitudes of 7,200 to 7,700 feet. Gravels 

of this erosional stage also occupy parts of sees. 34 and 35.

Agricultural activities in this township are confined chiefly to 

the valley floor of Middle Fork of Popo Agie River, which, although
24 PHOSPHATE IN WIND RIVER. JMOUNTAINS, WYO.

partly littered with bquldery glacial drift, has many prosperous 

ranches. Small areas are also under cultivation along and near 

Willow Creek, in the southeastern part of the township.

Exposures of the Phosphoria formation may be seen in almost 

all of the sharp ravines or canyon walls formed by the resistant 

limestone members. The phosphate rock where not completely exposed can readily be uncovered at favorable places. The following 

section, measured on a branch of Willow Creek in the SW. l/^ sec. 

25, shows nearly all of the Phosphoria formation.

Section of Phosphoria formation on North Fork of Willow Creek

Ft. in.

Limestone, massive, gray, fossiliferous__________ 27 6 - 

Shale, cherty in upper part, and nodular; surface resembles pebble dash _____ , 22 

Phosphate bed, oolitic (about 32 per cent of tricalcium

phosphate)_____________ _ ____ 7% 

Shale, bluish drab, slightly phosphatic__ ___ 10 

Chert ______________________________ 7 

Shale, bluish drab 3 

Phosphate (approximately 32 per cent of tricalcium

phosphate) 9 

Shale, bluish black, with phosphatic bands; weathered 

surface coated with blue film, especially in upper 

part of shale___ ___ 18 

Phosphate, upper 4 feet friable, lower 2 feet more resistant ; near base are fish teeth and other fossils (43.4 

per cent of tricalcium phosphate) _ _____ 6 

Limestone, gray; upper part fossiliferous _____ 10 

Interval, not examined in detail, mostly shaly limestone' 120 

Limestone, gray, massive, rich in fossils; Allerisma

plentiful_____ - - 20 

Shale, greenish ___ __ _ 4 

Phosphate bed having many Lingulidiscina and made up 

of phosphatic bands, intercalated with lean phosphatic 

limestone (44.7 per cent of tricalcium phosphate)__ 2 9 

Limestone, compact, dark gray, siliceous, fossiliferous,

with covered interval below ____ 40 

Tensleep sandstone, unmeasured.

The upper bed was measured and sampled at four localities in-, 

the township. It ranges from 3y2 *° 6 feet in thickness and is 

thickest in the southeastern part of the township, in sec. 25, where 

it is also the richest, carrying 49.2 per cent of tricalcium phosphate, 

compared with only 43.2 per cent in sec. 5. The exposures in sec. 25 

probably represent the upper bed at its best in the Wind River 

Mountains.

The lower bed is of less prospective value than the upper, being 

only 12 to 33 inches thick and not especially rich when the entire 

bed is included in the sample. The upper portion, 12 to 18 inches
TOWNSHIP DESCEIPTIONS 25

thick, is generally the richest in tricalcium phosphate, containing 

between 50 and 60 per cent. Beneath it is lean phosphatic limestone 

with thin richer layers made up largely of the phosphatized shells 

of Lingulidiscina. The lower bed was sampled at two points, and 

the results are shown on Plate III.

T. 31 N., B. 99 W.

The surface of T. 31 N., K. 99 W., has a relief of more than 2,500 

feet. The southwestern part constitutes the mountain slope of the 

Wind River Range, at the base of which is an anticlinal ridge about 

1,300 feet higher than the adjacent valley. East of Red Canyon 

Creek the red beds form a broken belt of country about a mile wide, 

beyond which are succeeding hogback ridges of higher rocks interspersed with shallow valleys. There is little wood in this part except a scrubby species of juniper that favors the most rocky slopes,

In the southwestern part of the township there is a small amount of 

pine timber along the principal ravines.

The township is about 10 miles south of Lander, and a daily stage 

to Atlantic follows a route southeastward across it along the valley 

of Red Canyon Creek. In this valley are several ranches where 

alfalfa hay is the principal crop. Young's ranch, at the mouth of 

the canyon of South Fork of Popo Agie River, has been occupied 

for over 40 years, and the owner has one of the largest and most 

successful apple orchards in the State.

The general dip of the beds along the main mountain slope is 

5°-25° NE., there being several terrace-like undulations. In the 

central part of the township is a sharp anticline which pitches northwestward and stops abruptly at its south end, near Deep Creek. 

The west flank is inclined at angles of 45° to 50°; the east flank at 

angles of 10° to 20°. At the south end of the anticline along Deep 

Creek there is a thrust fault having a displacement of about 30 feet.

In the NW. % sec. 8 and adjacent territory minor structural disturbances appear to have involved chiefly the Phosphoria beds, leaving the underlying rigid Tensleep sandstone practically unaffected 

as seen along the canyon walls. The disturbances were apparently 

in the form of bed thrusting and folding, there being local monoclinal undulations where the dip increases from 13°, the usual angle, 

to about 25°. The strike varies greatly from place to place. The 

resultant topography resembles that of a large landslide surface.

The strata exposed in the township include formations ranging 

from the Madison limestone to the Mancos shale. The Dakota sandstone and associated rocks, lying a few hundred feet above the top 

of the Chugwater red beds, form a hogback ridge that .extends across 

the northeast corner of the township. Beneath these beds are the 

weak Morrison and Sundance formations, which are represented by
26 PHOSPHATE IN WIND RIVER MOUNTAINS, WYO.

a broad, open valley. The .Chugwater formation is about 1,400 feet 

thick and has in its upper portion a massive sandstone member that 

forms a high ridge east of Red Canyon. The lower Chugwater 

beds, of brick-red color, appear in the prominent escarpment on the 

north side of the valley. The Dinwoody formation, underlying the 

Chugwater, is only 30 feet thick and consists of weak clay shale and 

brown flaggy limestone, with more resistant limestone beds at the 

base. The Phosphoria formation has the usual upper resistant limestone member that controls the long dip slopes which are so prominent along the mountain. The formation is 265 feet thick and rests 

on the Tensleep sandstone, which is about 400 feet thick.

The Phosphoria formation as seen along South Fork of Popo Agie 

River is illustrated by Plate II; A shows the upper bryozoan-bearing 

limestone, about 33 feet thick, which controls the dip-slope topography and also the positions of the two phosphate beds, and 5, 

which is a close view, shows the nodular chert underlying the upper 

bryozoan-bearing limestone. The lower part of this chert is shaly 

and has numerous phosphate bands from a fraction of an inch to 5 

inches in thickness. The cherty beds rest on brownish-black shale 

about 38 feet thick, which has thin phosphate bands in the lower 

portion. The upper phosphate bed, about 8 feet thick, lies at the 

base of the shale member. The beds in the middle of the Phosphoria 

formation are not well exposed, for, being less resistant, they form 

a sloping profile covered mostly by talus which supports a growth of 

juniper bushes. At 40 feet above the base of the formation is the 

lower phosphate bed, 2^2 fGet thick. It is overlain by 25 feet of white 

chalky limestone rich in fossils and underlain by siliceous dark-gray 

compact limestone having few fossils.

The first discovery of phosphate rock in the Lander district was

made at Young's ranch in 1909, by E. G. Woodruff, who without 

suspecting its phosphatic character recognized the rock as the same 

as the " oil sand " in the Dallas oil field. It is of interest to note 

that this discovery was made in the region where the phosphate beds 

are most valuable, for they are at their best in this township and the 

adjoining ones to the north and south.

The upper bed ranges from 3 to 7 feet in thickness and as usual 

contains shaly calcareous layers low in phosphate, interbedded with 

richly phosphatic layers, Some of the individual laminae contain 

nearly 60 per cent of tricalcium phosphate, but when the percentage 

in these is averaged with that of the lean laminae the content of the 

bed as a whole is 35 to 40 per cent, a low grade as compared with 

that of the lower bed. The dark granular rock from the upper bed 

when freshly broken gives a noticeable oily odor.

At the sampling point in sec. 8, near Young's ranch, the upper 

bed has a thickness of 86 inches and averages 35.5 per cent of
T. 30 N., K. 90 W. 27

tricalcium phosphate. In sec. 33 the thickness is about 3 feet and 

the tricalcium phosphate content 36.8 per cent. Above the principal 

bed are three or more thin bands of phosphate rock distributed 

through the dark-brown shale.

The lower phosphate bed has been uncovered in sec. 8 in a prospect 

pit dug in the search for gilsonite. The rock is nearly black and contains calcite vugs lined with more or less black bituminous material. 

Fossils are abundant throughout the bed. In addition to the everpresent disk-shaped shells of Lingulidiscina they include abundant 

small pelecypods of the genus Nucula. The lower bed, like the upper, 

contains thin laminae of shale and limestone that considerably reduce the tricalcium phosphate average when included in the sample. 

The results of analysis of a gross sample from a 2%-foot bed in 

Little Popo Agie Canyon give 53.2 per cent, and of a sample from 

a 4-foot bed on Deep Creek in sec. 26, 52.2 per cent. Samples from 

select laminae would doubtless yield considerably more than 60 

per cent. Sections of the bed are given on the map (PI. Ill) and 

also in detail below.

Section of lower phosphate bed on Little Popo Agie River

Inches 

Phosphate rock____________,____________________ 5

Limestone, phosphatic______________________ 4

Shale. __________________ -_ 4 

Phosphate rock___________________________ 1. 5

Shale _______ _________________________ 2. 5

Phosphate rock_____________________

Shale____________-__________.

Phosphate rock filled with fossil shells.

Tricalcium phosphate, 

53.2 per cent

4.5 

1.5

24

Limestone, dark, slightly phosphatic, unmeasured.

Section of luircr phosphate bed on Deep Creek in the SW. % -sec. 26, T. Si N.t

R. 99 W.

Inches 

Phosphate______________________________ 5

Clay __________________________________ 3

Phosphate, fossiliferous_____________

Shale, phosphatic_________________

Phosphate, fossiliferous_____________

Phosphate made up of Lingulidiscina

shells.

Tricalcium phosphate, 

52.2 per cent

12

2.5

24

10

Limestone, slightly phosphatic_______________ _- 18 

Chert, unmeasured.

T. 30 N., R. 99 W.

T. 30 N., R. 99 W. sixth principal meridian, lies about 18 miles 

south of Lander. The Lander-Pinedale stage route crosses southwestward through its central portion. Although the southwestern 

two-thirds of the township is a part of the Wind River Mountains, 

5525 24 3
28 PHOSPHATE IN WIND RIVER MOUNTAINS, WYO.

the relief is not great, and the surface is only moderately rugged. 

Timber is not nearly so plentiful as in the townships to the northwest, and the scattered woodlands include many thickets of quaking 

aspen.

Over most of the northeastern part of the township is a tableland approximately 7,000 feet in altitude, covered with Quaternary 

.gravel, locally underlain by clays and arkose sands which rest upon 

the beveled edges of the old rock formations. The gravel consists 

in large part of materials derived from crystalline-rock outcrops in 

the mountains to the south, there being an abundance of magnetite 

schist pebbles which deflect the needle to so great an extent that 

compass surveys are impracticable.

Twin Creek, Usher Creek, and Stanbaugh Creek are all small 

streams with narrow valleys. At a few places their valley bottoms 

widen sufficiently to attract the settler, but the altitude is so great 

that about the only successful crop is hay. Ranching is carried on 

in a small way in sees. 1, 2. and 12, and other areas would probably 

be utilized were there a larger water supply for irrigation.

The structure of the portion of the township included in this 

report shows no irregularity, the beds being inclined northeastward 

at angles of 8° to 12°. The Tensleep, Phosphoria, Dinwoody, and 

Chugwater formations are covered throughout considerable areas 

by the outwash gravels already mentioned, which probably correspond in age with the deposits on Table Mountain. The gravels are 

more or less auriferous, and in past years several projects to Avork 

them for gold have been promoted.

The Phosphoria beds are well exposed along Twin Creek at the 

east side of sec. 11, where the following section was measured. The 

exposures also include beds consisting of soft greenish-gray shales

about 35 feet thick representing the entire Dinwoody formation.

Section of Phosphoria formation on Twin Creek in sees. 11 and 12, T< 30 N.,

R. 99 W.

Ft In.

Limestone, grayish; lower portion has cherty nodules__ 17 

Chert, upper part nodules embedded in limestone, lower

part nodules in greenish shaly matrix___________ 16 

Shale, greenish drab, containing green nodular concretions. 1 

Shale, dark drab___ ___________________ 10 

Phosphate, impure (21.5 per cent of tricalcium phosphate). 4 

Shale, drab______ __________________ 22 

Phosphate (33.8 per cent of tricalcium phosphate)____ 6 

Shale, dark drab, fissile ___________________ 7 6 

Phosphate, friable, calcareous, dark (37.2 per cent of triPhosphate, dark g?ay_ __,_ __ __ _

Limestone, oily, phosphatic, argillaceous __ 

Phosphate-- _ __ _____ _ _ _

247 per centf

of tricalcium 1 

ohosnhate

1 4

5
T. 30 N v E. 98 W. 29

Limestone, slightly phosphatic (4 per cent of tricalcium Ft. in.

phosphate)____ _____________________ 1 2

Phosphate, friable, rich looking; contains small fossils

(41.9 per cent of tricalcium phosphate) _ 1 7 

Limestone, phosphatic, grayish (34 per cent of tricalcium

phosphate)________ ____________ ____ 1 5

Limestone, slightly phosphatic________________ 3 6

Limestone, pinkish gray, fossiliferous__ _________ 2

Interval not exposed _________________ ___ 160± 

LinguUdi-scina-be&rlng phosphate bed, sampled on Usher

Creek, where it contains 60.9 per cent of tricalcium

phosphate ___________________________ 4 

Limestone, siliceous, rich in fossils, alternating with

cherty beds___________________________ 38 

Tensleep sandstone, unmeasured.

The upper phosphate bed consists of a number of more or less 

calcareous laminae, none of which were found to contain more than 

43 per cent of tricalcium phosphate. A gross sample representing 

5 feet of the richest portion gives about 37 per cent.

Exposures of the lower bed were found only on Usher Creek near 

the north edge of sec. 24: It is a single rich-looking dark-gray 

layer 4 feet thick, yielding on analysis 60.9 per cent of tricalcium 

phosphate. Float fragments of the bed are easily discovered along 

the outcrop, for the reason that the weathered rock assumes a bluishgray skimmed-milk color. The flat shells of the fossil Lingulidiacina, the size of a 5-cent coin, are always to be seen in it.

T. 30 N., B. 98 W.

The surface of T. 30 N., R. 98 W., is in part made up of low 

hogback hills in Mesozoic strata, with extensive gravel and sand 

covered table-lands in the southwestern portion above which the 

older tilted strata project here and there. The general altitude of 

the table-lands is about 7,000 feet, and that, of the lowest valleys in 

the northeastern part of the township is about 6.300 feet. The area is 

used solely for sheep grazing.

There is but little opportunity to observe the details of structure 

and stratigraphy in the southwestern part of the township, for the 

reason that the rocks are concealed by an extensive blanket of 

Tertiary clays and arkosic sands. Over these grayish to white 

beds is a thin veneer of gravel, made up in large part of pebbles 

of hornblende and magnetite schist. It is certain, however, that a 

fault of large displacement extends across the southern part of the 

township with a trend of about N. 20° E., almost at right angles to 

the strike of the nearest hogback exposures of the Phosphoria and 

Tensleep beds. On the south side of the fault, 3 miles to the east
30 PHOSPHATE IN WIND RIVER MOUNTAINS, WYO.

of the beds on the north side, is an isolated low ridge of Tensleep 

sandstone that strikes about N. 50° W. and dips 22° NE. This 

may be assumed to denote a stratigraphic displacement of more 

than 1 mile of the strata on opposite sides of the fault. There is, 

however, another possible interpretation. Along Stanbaugh Creek 

in sec. 20 is a well-defined anticline trending southeastward and 

extending under the cover of Tertiary beds in sec. 28. It is barely 

possible that this fold, although narrow and insignificant in sec. 20, 

broadens toward the southeast, and that its axis changes to a more 

easterly direction. The upper phosphate bed as projected under the 

Tertiary covering might under this interpretation be supposed to 

extend in an easterly direction to the fault at a point approximately 

1 mile west of the same bed on the other side of the fault, instead 

of nearly 3 miles, as indicated on the map.

In the description of T. 30 N., R. 99 W., adjoining this one on 

the west, is given a measurement of the Phosphoria beds which 

may also be regarded as representative of this area.

Fair but incomplete exposures of the Phosphoria beds may be seen 

along Stanbaugh Creek in sees. 19, 20, and 30, but they are 

not so good as those in sec. 1, which are described below under the 

heading " Sheep Mountain anticline."

Natural exposures of the phosphate beds are few in this township, and at only one point was an outcrop of the upper bed suitable 

for sampling found. The lower bed is even less satisfactorily exposed and was not sampled within the township. The positions of 

both the upper and lower beds are readily discovered by means of 

the phosphate float, which appears as dark-brown granular rock 

with the typical bluish-gray " bloom " on weathered surfaces.

The upper phosphate bed was sampled on the banks of Stanbaugh 

Creek in sec. 20, where it was found to be 44 inches thick and to contain 45 per cent of tricalcium phosphate. The lower bed where 

sampled on Usher Creek in sec. 24 of the adjoining township to the 

west is 48 inches thick and contains 60.9 per cent of tricalcium phosphate.

Evidently it thins northeastward under cover, for it is missing 

along the slopes of Shot Mountain, in the northeastern part of the 

township.

SHEEP MOUNTAIN ANTICLINE, T. 30 N., B. 97 W., AND T. 31 N.,

US. 97 AND 98 W.

SURFACE FEATURES

Sheep Mountain is a conspicuous topographic feature resulting 

from the erosion of hard Paleozoic rocks which have been folded 

into an anticline. The highest portion of the mountain is formed 

by sandstone beds of the Tensleep formation, which in the northwest-
SHEEP MOUNTAIN ANTICLINE 31

era part of T. 30 N., E. 97 W., have an altitude of a little more than 

7,500 feet. The central axis of the mountain trends roughly southeast, swinging to east in the eastern part of the township. The str'ata 

dip away from this central axis, and the mountain is encircled by 

successively lower hogback ridges of the red beds and overlying 

formations, which are separated from harder rocks forming the central mountain m'ass by a strike valley. In the central part of T. 

30 N., E. 97 W., is a low gap that extends northeastward across the 

mountain and is used by sheepmen who have made wagon trails that 

give access to various parts of the bench lands e'ast of Sheep Mountain. There are a number of ranches close to the base of the mountain two at the upper and lower ends of Beaver Creek canyon, several along Twin Creek on the southwest side, and another at the 

northwest end, where there 'are large springs.

Beaver Creek, the principal stream within the area, has not a 

perennial flow throughout its course, being fed chiefly by local springs 

except early in the summer, when the melting of the snows in the 

mountains to the southwest brings a large flow. The stream has cut 

a deeply notched canyon across Sheep Mountain in a fairly direct 

course, regardless of the hardness of the strata. The extension of a 

drainage channel across a seemingly formidable topographic barrier 

is displayed on a grander scale by Wind Eiver. which turns northward from the lowlands of Wind Eiver Basin into a precipitous canyon with walls 2,000 feet in height cut through the Owl Creek Mountains. Drainage lines such as these may be very ancient, for their 

courses have evidently been maintained either since the initiation of 

mountain-making processes or at any rate since late Tertiary time.

GEOLOGIC FEATURES

Sheep Mountain is in alinement with the Dallas, Lander, and Fort 

Washakie anticlines, whose axes parallel the Wind Eiver Eange. It 

differs from the others, however, in being much faulted and of greater 

magnitude, but it displays the general habit common to all anticlinal 

folds in the region in that the strata on the southwest side dip much 

more steeply than those on the northeast side.

A fault of considerable prominence extends a little north of east 

across Sheep Mountain and appears to coincide with a fault of large 

displacement that occurs along the Wind Eiver Mountain front about 

4 miles to the southwest. The displacement, for the most part vertical, with the north side depressed, may be as much as 4,000 feet. 

From the vicinity of Beaver Creek, in sec. 22, T. 30 N., E. 97 W., the 

eastward extension of the fault plane is conspicuously indicated for 

several miles by a wall of Madison limestone dragged into a vertical 

position and adjoined on the south by Cambrian and pre-Cambrian 

rocks.
32 PHOSPHATE IN WIND RIVER MOUNTAINS, WYO.

North of the principal fault in Sheep Mountain and at about right 

angles to it are two overthrust faults with the displacement toward 

the northeast. One, extending along the crest of the mountain, has 

carried the Tensleep sandstone over the Phosphoria beds. The other, 

on the northeast slope, has had a similar effect and in addition has 

.carried a block of Phosphoria beds over Chugwater strata. Another 

fault of considerable prominence has modified the structure of the 

anticline in its southern portion, beds well up in the Cretaceous along 

the mountain base being in contact with Cambrian shales east of 

Beaver Creek in sees. 35 and 36, T. 30 N., R. 97V. The fault plane 

trends nearly due east, and its extension in both directions is concealed by a cover of Tertiary deposits.

Rocks of the entire Paleozoic sequence are exposed along Beaver 

Creek canyon in sec. 26, T. 30 N., R. 97 W. The structure is somewhat complicated b}^ minor faults, but the exposures are favorable 

for detailed stratigraphic study. The crystalline rocks appear at 

the north edge of sec. 26 on the east bank of Beaver Creek, and the 

outcrop widens eastward from this vertex and occupies a large area 

in the adjoining toAA'nship to the east. The rock is granitic in composition and has a slightly gneissoid texture. The identity of the 

limestone series is not, certain, but it seems probable that the ferruginous shales and thin-bedded limestones of the Cambrian are dire-ctry overlain by the Madison limestone, which is considerably reduced in thickness from its maximum in the Wind River Range. 

The Tensleep sandstones show the usual massive, cross-bedded character, are ripple marked on the bedding planes, and locally contain 

indistinct impressions of plants. Their thickness is about 300 feet.

The Phosphoria formation was measured on Beaver Creek in sec. 

10; T. 30 N., R. 97 W., and the thickness was found to be 283 feet.

The folloAving details were recorded at that point:

Section of PhospJwria and Dimroofly formations on Bearer Creek

Chugwater formation:

Red sandy shales, unmeasured. 

Dimvoody formation: Ft. in.

Lower portion thin-bedded drab shales; upper 6 feet

gray flaggy sandstone, weathering brownish____ 27 

Phosphoria formation:

Chert, gray, granular, rusty-appearing rock which resembles fine-grained quartzite. It has been mistaken for a quartz ledge and prospected for gold in 

places. Under cover this rock is mostly siliceous 

limestone__________________________ 17

Clay, yellowish, marly, with chert nodules and geodes 

of quartz and calcite__________________ 6

Limestone, brownish gray, with calcite geodes_____ 6

Chert nodules in a matrix of greenish sandy shale__ 17
SUMMARY OF PHOSPHATE BEDS 33

Phosphoria formation Continued. Ft. In. 

Shale, black to drab; weathers to talus slopes____ 23 

Produotits-be&ring phosphate bed:

Phosphate, grayish, pebbly, argillaceous, containing Prodtictus nevadensis (29.3 per cent tricalcium phosphate)_______________-__ 5 6 

Phosphate, impure, calcareous ___________ 1 6 

Shale, calcareous, phosphatic________-__ 8 

Limestone, phosphatic, a mass of fossils, chiefly 

Productus ___________________________________ 2 6

Limestone, massive, brownish gray, filled with

fossils, slightly phosphatic_________-__ 17 

Shales and limestone; drab-gray shales, sandstone, chert beds, and intercalated limestones, 

few of which are well exposed_________ 183

Tensleep sandstone, base not exposed____________ 300±

The upper or Proteus-bearing phosphate bed is the only one 

found in the Phosphoria formation in Sheep Mountain, the lower 

bed being so insignificant that even its position can be found only 

with difficulty. The upper bed was measured and sampled at six 

points, all within T. 30 N., E. 97 W. Three of the localities are in 

sees. 6 and 7, where there are almost continuous exposures; the others 

are in sees. 9. 10, and 12. The bed ranges from o~y2 to 11 feet 

in thickness and is thickest in the western part of the township. 

The rock is almost without exception leanly phosphatic, samples of 

the entire bed yielding less than 30 per cent of tricalcium phosphate 

and samples selected to represent the richest-looking laminae yielding 

at best less than 40 per cent. In appearance the rock resembles an 

impure argillaceous limestone, being gray in color and with a more

or less oolitic texture caused by the scattered phosphate oolites.

«

SUMMARY OF PHOSPHATE BEDS

On the north slope of the Wind River Mountains there are two 

principal phosphate beds in the Phosphoria formation, the lower one 

lying 40 to 55 feet above the base and the upper 60 to 75 feet below 

the top. The upper is the more persistent but varies considerably in 

thickness and percentage of tricalcium phosphate from place to 

place. The loAver one, although varying greatly in thickness and 

richness and absent in the Sheep Mountain uplift, is in its best 

development richer than the upper and therefore more promising 

as a source of phosphate rock for commercial purposes.

Loiver bed. The lower phosphate bed is at its best in T. 30 N., R. 

99 W., Avhere, as sampled on Usher Creek in sec. 24, it is 4 feet thick 

and contains 27.85 per cent of phosphorus pentoxide, equivalent to 

about 61 per cent of tricalcium phosphate. On Beaver Creek, 8 

miles southeast of the Usher Creek locality, in sec. 5, T. 29 N., R.
34 PHOSPHATE IN WIND RIVER MOUNTAINS, WYO.

97 W., the same bed is only 10 inches thick, and at a number of 

points farther south, on and near Sweetwater River, it is absent. The 

bed likewise thins eastward under cover from Usher Creek and is 

missing in the Sheep Mountain uplift, in Tps. 30 and 31 N., R. 97 

W. It seems safe to assume that the lower bed is present and of 

commercial value northwestward from Usher Creek for at least 

15 miles along the strike, for at the sampling points on Deep Creek, 

Little Popo Agie River, and Willow Creek the bed is only slightly 

less promising than on Usher Creek. On Deep Creek, in sec. 26, T. 

31 N., R. 99 W., the thickness is nearly 5 feet and the tricalcium 

phosphate content 52.2 per cent; on Little Popo Agie River, in sec. 

8, T. 31 N., R, 99 W., the thickness is 2V2 feet and the phosphate content 53.2 per cent; and on Willow Creek, in sec. 26, T. 32 

N., R. 100 W., the bed is a little less than 3 feet thick and contains 

44.7 per cent of tricalcium phosphate. On the Middle Fork of 

Popo Agie River, in sec. 8, T. 32 N., R. 100 W., the bed thins to 

less than 2 feet, but on Squaw Creek, in sec. 29, T. 33 N., R. 101 W., 

a sample was taken from a bed 32 inches thick which contained 57.9 

per cent of tricalcium phosphate. The Squaw Creek locality is the 

most northerly point where the bed was found to be of promising 

thickness and richness.

Upper bed. The upper bed differs from the lower in that it contains a large amount of sandy and clayey impurities and is generally 

made up of several layers of phosphate rock interbedded with shaly 

material. Some of the laminae a foot or so thick may be found to 

contain as much as 60 per cent of tricalcium phosphate, but a sample 

selected to represent layers having an aggregate thickness of several 

feet commonly shows no more than 40 per cent. The upper bed is 

most favorably developed from Baldwin Creek opposite Lander 

southeast to Usher Creek, thus agreeing in this respect with the lower 

bed. The following table shows the thickness and percentage of 

tricalcium phosphate of the upper bed at a number of localities:

Character of upper phosphate bed where most favorably developed

Baldwin Creek, sec. 18, T. 33 N.,

Squaw Creek, sec. 29, T. 33 N., R

Sec. 5, T. 32 N., R. 100 W........

Middle Fork of Popo Agie River,

Sec. 27, T. 32 N., R. 100 W. ..:...

Sec. 25, T. 32 N., R. 100 W.......

Little Popo Agie River, sec. 8, T.

Sec. 33, T. 31 N., R. 99 W.. ......

Locality

R. 101 W........................ ...... .

. 101 W. .............................

sec. 8, T. 32 N., R. 100 W. ....................

31 N., R. 99 W...-.... .....................

Thickness 

(inches)

97

1Q

42

42

72

60

86

OQ

Tricalcium 

phosphate 

content 

(per cent)

3*; s

42 0

49.2

 35.5
PHOSPHATE IK WIND RIVER MOUNTAINS, WYO. 35

PHYSICAL PROPERTIES

The high-grade phosphate rock in the Wind Kiver Mountains resembles other deposits in the Kocky Mountain region 

in that it is oolitic in texture, of high specific gravity, dark 

brown to black when freshly exposed, and bluish gray on the weathered surface. The shale, limestone, and chert that are closely associated with the upper phosphate bed are likewise so similar to 

those in the phosphate fields of northeastern Utah and adjacent 

parts of Idaho that the observer familiar with those localities would 

at once notice the resemblance. An important difference, however, 

in the geologic sections of the two regions is that in the Wind River 

Eange phosphate occurs at a lower horizon not known to be represented in Utah and Idaho.

The oolitic texture is most noticeable in the rock richest in phosphate, the rounded black granules giving an appearance of fish roe. 

In general, however, the oolites are intimately mixed with sand 

grains, clay, and calcareous material which forms a cementing 

matrix. Large fossil brachiopods of the genus Productus are plentiful in the basal portion of the upper phosphate bed at many localities. There is not everywhere a sharp demarkation between the 

phosphate bed and the underlying limestone, the latter commonly 

containing more or less oolitic granules scattered through the upper 

portion. The lower phosphate bed has fewer oolitic granules than 

the upper bed and consists in much larger part of fossils, the shells 

of which are phosphatized. Lingulidiscina utahensis, the most 

abundant fossil, has a shell of essentially phosphatic composition 

and appears to have furnished in large part the phosphatic material 

of this horizon. The shells of Nucula and other small pelecypods 

that are plentiful in the bed are not known to be originally richly 

phosphatic, but their phosphatized casts, together with a dark 

amorphous rock, make up the bulk of the bed.

The specific gravity of the richer phosphate rock is noticeably 

greater than that of limestone and sandstone, being in certain specimens as high as 2.8. This property, together with the peculiar 

bluish-gray color of the weathered rock, makes it easy to recognize 

float particles and thus discover the outcrop. ;

The freshly broken phosphate rock generally has a peculiar oily 

odor, which is not surprising, as the same rock under cover is productive of oil in this part of Wyoming. In fact, the presence of phosphate rock in the region became known in 1909 through its content 

of oil. The first specimen was collected at Young's ranch, on Little 

Popo Agie River, by E. G. Woodruff, who was searching for an
36 PHOSPHATE IN WIND RIVER MOUNTAINS, WYO.

outcrop of the "oil sand" that was productive in the oil wells at 

Dallas. The specimen was shown to H. S. Gale, who at once noticed 

its resemblance to the Idaho phosphate rock, and on analysis in the 

chemical laboratory of the United States Geological Survey it was 

found to contain 65 per cent of tricalcium phosphate.

COMPOSITION

In the township descriptions are given the results of numerous 

partial analyses showing the percentage of phosphorus calculated to 

tricalcium phosphate. It is not unreasonable to assume that the 

phosphate is in this form, for the following chemic.al analyses show 

that iron and alumina are present in only small amounts. The_chief 

impurrtjes-4n. the rock phosphate are sandy, -clayey,-more or less 

calcareous sediments.

Analyses of phosphate rock from Wind River Mountain 

[W. C. Wheeler and Benedict Salkover, analysts]

No.

1

2

3

4

5

6

7

8

9

PsOs

19.78 

27.90

19.87

22.52

24.33

20.30

17.01

21.03

20.35

Equivalent

in tricalcium phosphate

43.22 

60.96

43.41

49.20

53.16

44.35

37.16

45.95

44.46

CaO

34. 11 

42.91

39.01

38.62

40.11

35.63

34.76

38.05

38.00

(A.l,Fe)jOa)

1.33 

1.93

2.76

1.79

2.04

1.70

1.92

1.30

2.66

1. Upper bed, SE. J£ sec. 18, T. 3 N., R. 4 W. Wind River meridian.

2. Lower bed, NE. % sec. 21, T. 32 N., R. 100 W. sixth principal meridian.

3. Upper bed, NE. % sec. 27, T. 32 N., R. 100 W. 

. 4. Upper bed, SW. X sec. 25, T. 32 N., R. 100 W.

5. Lower bed, sec. 9, T. 31 N., R. 99 W.

6. Upper bed, sec. 9, T. 31 N., R. 99 W.

7. Upper bed, SE. Jisec. 11, T. 30 N., R. 99 W.

8. Upper bed, sec. 20, T. 30 N., R. 98 W.

9. Upper bed, NE. \i sec. 30, T. 31 N., R. 98 W.

The phosphate rock mined for shipment in the vicinity of Bear 

Lake, southeastern Idaho and the adjacent portion of Utah, generally contains a little more than TO per cent of tricalcium phosphate 

and less than 3 per cent of iron and alumina. It is therefore considerabty richer than the rock in the Lander district, the best of which 

}delds on analysis an amount of phosphoric acid equivalent to about 

60 per cent of tricalcium phosphate,

UTILIZATION AND METHODS OF TREATMENT

Phosphate rock finds its most important use as a soil fertilizer. 

The finely ground rock may be used direct and also as an ingredient 

of artificial fertilizers. In general, however, the rock is put through
UTILIZATION AND METHODS OF TREATMENT 37

a process of treatment which renders its phosphorus content more 

soluble.15

The method of treatment generally in practice is known as the 

acid treatment, in which water-soluble phosphates are produced by 

the use of sulphuric acid. The process consists in treating the 

ground phosphate rock with an equal weight of acid, and the resulting product is a calcium-acid phosphate. It is said that in factory 

practice the product of this treatment sometimes remains moist and 

gummy so that it is difficult to handle and that it tends to eat the 

cloth bags in which it is placed for shipment. Iron and alumina 

are supposed to be the cause of this undesirable property in the 

manufactured product, as their sulphates show a tendency to take 

up moisture in a damp atmosphere. The combined percentage of

the two radicals computed in the oxide form should, according to

the manufacturers, not be more than 4 or 5 per cent. The analyses 

of samples from the Lander district (see p. 36) show the iron and 

alumina to be within the required limits.

The Lander district is rather remote from a source of supply of 

sulphuric acid, there being no smelters in operation in Wyoming and 

the nearest ones from which a supply might be derived being in Salt 

Lake City or Anaconda. The acid process of treatment would therefore be expensive.

A report has recently been received concerning another process of 

treatment practiced in Italy and elsewhere in the Mediterranean 

region. It is said to consist in heating the finely ground phosphate 

rock to 600°-700° C. with a mixture of calcium, magnesium, and 

sodium carbonates. The calcined mass is then moistened and diluted 

with earth or sand until the phosphoric acid content is about 20 per 

cent. The product, " tetraphosphate," is said to be equal to the ordinary superphosphate in fertilizing power and also cheaper to produce. The beneficial results from the use of the " tetraphosphate " 

as manufactured in Italy have been questioned by certain chemists. 

If on further investigation the merits of the product derived by this 

method are established, the process could readily be put into practice 

in the Lander district.

16 Methods of manufacture of phosphatic fertilizers are described by W. H. Waggaman 

and W. H. Fry in U. S. Dept. Agr. Bull. 312, 1915.

INDEX

Agriculture in the region. 4-5,18,19,22,23-24,25,28 

Amsden formation, nature and occurrence of. 9-10 

Analyses of phosphate rock.... .......... 36

Bighorn dolomite, nature and occurrence of.. 8-9

Ohugwater formation, nature and occurrence

of............................... 13-14

Climate of the region.__......._....._ 4-5

Composition of the phosphate rock_...... 36

Cretaceous rocks, nature and occurrence of.. 14,15

"Darby formation," occurrence of-..._... 9

Dinwoody formation, age of;_____._ 10

nature of...-.-...--..-.....-........-... 13

Discovery of phosphate rock in the region. 26,35-36

"Edgewise conglomerate," occurrence of.... 8 

Embar formation of Darton, occurrence and

divisions of.. ................. 10-11

Faults in the region____. ______ 17,31-32 

Field work, record of.__..________ 2-3 

Flathead sandstone, occurrence of.. ___ 7

Qallatin limestone, nature and occurrence of. 8 

Geography of the Wind Kiver Mountains... 3-6 

Geologic map of northeast slope of Wind

River Mountains_______. 18 

Glacial drift, occurrence of_________ 16 

Gravel deposits, occurrence of_.....__ 16-17 

Gros Ventre formation, nature and occurrence

of............................... 7-8

Lower phosphate bed, distribution of.._... 33-34

Madison limestone, nature and occurrence of. 9 

Map, geologic, of northeast slope of Wind

River Mountains________ 18 

Market for Rocky Mountain phosphate rock. 1-2 

Mineral resources of the region __. 5 

Morrison formation, features of......__ 14

Output of Rocky Mountain phosphate rock.

Phosphoria formation, exposures of, plate

showing____._______.. 11 

fossils in_.__.__................. 11-12,13

nature and members of..____.___ 11-13 

section of............................... 11-12

Pre-Cambrian rocks, features of..____.. 6-7 

Properties of the phosphate rock.____ 35

Red Creek canyon, view toward. 10

Section in T. 2 S., R. 2 W_.___............... 20-21

on Baldwin Creek................ 23

on Beaver Creek.......___.____.. 32-33

on Deep Creek.....___....___.... 27

on Little Popo Agie River.______ 27 

on Mexican Creek............... .. 22

on North Fork of Willow Creek ......... 24

on South Fork of Little Wind River..... 11-12

on Twin Creek............ ____.. 28-29

Settlements in the region 5 

Sheep Mountain anticline, geologic features

of........ ..................... 31-33

su face features of....___ __ 30-31

Stratigraphy of the region_ ___ 6-17 

Streams of the mountain slopes_______ 4 

Structure of the Wind River Mountains.. 17 

Sundance formation, features of.._.. 14

Tensleep sandstone,nature and occurrence of. 10 

Tertiary strata, nature and occurrence of__ 15-16 

Tetraphosphate, production and value of.... 37

Timber of the region.....___._____.. 6

Topography of Wind River Basin____... 3-4 

Township descriptions:

T. 1 N., R. 3 W-........................ 18

T. 30 N., R. 97 W....................... 30-33

T. 30 N., R. 98 W............. ..... 29-30

T. 30 N., R. 99 W....................... 27-29

T. 31 N., Rs. 97 and 98 W............... 30-33

T. 31 N., R. 99 W....................... 25-27

T. 32 N., R. 100 W...................... 23-25

T. 33 N., R. 100 W...................... 22-23

T. 33 N., R. 101 W...................... 21-22

T. 1 S., Rs. 2 and 3 W................... 19

T. 2 S., Rs. 1 and 2 W................... 20-21

Transportation in the region. .__.. _.. 5-6 

Treatment of phosphate rock________ 36-37

Upper phosphate bed, distribution of.__.. 34 

Wind River Basin, plate showing____.. 10

39

o