ANTICLINES IN CENTRAL WYOMING.

By C. J. HARES.

INTRODUCTION.

The area herein designated central Wyoming, as shown in figure 16, 

covers nearly 5,000 square miles in Natrona and Fremont counties 

west of Casper and southeast of Lander, and includes no proved oil

FIGURE 16. Index map showing position of area designated central Wyoming.

fields. This area was investigated primarily to ascertain the possibilities of oil, and as a result it was found that the Carboniferous 

and Cretaceous formations which produce oil in other Rocky Mountain 

fields are well developed in central Wyoming and in places the oil seeps 

from them, but that in only a few places are these formations covered

43768° Bull. 641 17 16 233
234 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART II.

by impervious shale and within reach of the drill in folds favorable 

for the accumulation of oil and gas. The favorable folds are the Pine 

dome, the Oil Mountain anticline, the anticlines between Poison 

Spider and South Casper creeks, and the Emigrant Gap, Iron Creek, 

North Casper Creek, and Bates Hole anticlines, but even these most 

favorable folds may be barren of oil. The Cretaceous oil sands are 

below the surface in the Big Sand Draw anticline, in the anticline 

southwest of Powder River, and in the dome (?) on Wallace Creek, 

but each one has some disqualifying features. The oil-bearing formation may be too far below the surface to be easily reached by the 

drill, or the anticline may be incomplete that is, the axis may pitch 

in one direction only, allowing any possible oil that the sand may have 

originally contained to migrate upward along the strata to the surface 

and to escape, either during the period of erosion prior to the deposition of the flat-lying variegated Tertiary beds that rest on the truncated edges of the folded Cretaceous and Carboniferous formations or 

during the present erosion period.

The area is in the Wyoming lowlands of the Rocky Mountain division of the United States, and is one of varied character, as it includes 

mountains, high escarpments, plateaus, badlands, and some large 

streams, but even though the area lies across the backbone of the 

Rocky Mountains and extends nearly to the Continental Divide, it is 

devoid of lofty snow-capped peaks. It is a natural pass over the 

mountains where the altitudes range from a little over 5,000 to 8,210 

feet. This pass was chosen by the pioneers journeying overland to 

California and other parts of the far West. The Laramie Mountains 

border it on the southeast, the foothills of the Bighorn Mountains extend into the northeast part, and the Ferris, Pedro, Freezeout, and 

Seminoe mountains lie to the south. Sheep Mountain, on the western 

edge of the field, forms a part of the foothills of the Wind River Mountains. Crooks Mountain and Green Mountain are situated along the 

southern border and the Granite Mountains, in the middle-southern 

part of the area, are bare r-ugged granitic masses rising to an altitude 

of 8,040 feet in Hayden Peak, about 2,000 feet above the Sweetwater 

Valley. Sweetwater River unites with the North Platte in the Pathfinder reservoir, and the North Platte crosses the extreme southeastern 

part of the area and flows eastward into the Missouri. Twin Creek, 

which drains the northwest corner, flows into Little Popo 'Agie River, 

a tributary of Wind River. Beaver, Conant, Deer, and Muskrat 

creeks flow northward into Wind River and eventually into the Missouri by way of Bighorn and Yellowstone rivers. ~ Wallace Creek, an 

upper tributary of Powder River, flows northeastward and eventually 

into the Yellowstone. The Rattlesnake Mountains, which rise 8,210 

feet above sea level in the middle of the area, with the Sweetwater 

escarpment, form a part of the divides between these river systems.
ANTICLINES IN CENTRAL WYOMING. 235

5

The area may be reached from the east by the Chicago & Northwestern and Chicago, Burlington & Quincy railways, which cross the 

northern part of the area, or from the south by journeying 50 miles 

overland from Rawlins or other stations on the Union Pacific Railroad. The country is so sparsely settled and the land is so rough 

that many of the wagon roads are mere trails and usually follow of 

necessity the easiest route between towns or between some ranch 

and the nearest town on a railroad. Intricate badlands and other 

uneven features make travel difficult and haulage slow and unfit 

the land for agriculture.

Prospectors have been attracted by the indications of oil about 

the anticlines, but the rough land, the scarcity of permanent streams, 

and the remote location of good springs and fuel have controlled 

the location of drilled wells to the extent of preventing the prospecting of some of the more favorable parts of the anticlines for oil or 

gas. In addition to high freight rates there are excessive charges 

for teaming overland to the wells, most of which are from 10 to 30 

miles from a railroad.

The subbituminous coal beds west of the Pine and Oil mountains, 

east of the Rattlesnake Mountains, north of the Dutton anticline, 

east of Alkali Butte, and on Big Sand Draw are available for fuel 

in these localities, but in the eastern part of the area coal beds are 

absent and other sources of fuel must be fpund. In the northeast 

corner of the area oil is available from the Salt Creek field by a 

day's haul, and in the eastern part by a similar haul from Casper. 

Timber is scarce, and most of the trees are scrub pine and cottonwood. The better timber is restricted to the higher mountains.

Prospecting for oil and gas in central Wyoming, because of the 

surface conditions outlined above, is expensive.

The geologic work upon which this report is based was begun in 

July, 1913, and completed in the autumn of 1914.

ACKNOWLEDGMENTS.

The writer appreciates the suggestions and criticisms of M. R. 

Campbell, who had general supervision of the work, and gratefully 

acknowledges the assistance of his associates in the field, M. W. 

Ball, Stuart St. Clair, J. B. Reeside, jr., K. C. Heald, and A. C. 

Collins. . Many kindnesses were extended to the party during both 

field seasons by the ranchers and other persons living in the area, 

also by the oil companies engaged in prospecting the region

WATER SUPPLY.

Sweetwater River unites with the North Platte in the great Pathfinder reservoir, which stores water during the flood seasons for 

irrigation in eastern Wyoming and western Nebraska. These rivers
236 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART II.

and most of the creeks near their sources contain running water 

throughout the year, but the smaller creeks flow only early in 

the spring or after heavy showers. Even Powder River during the 

summer goes dry along most of its course, and though Beaver Creek 

supports trout above Hailey it runs dry farther down. As the 

precipitation averages only about 10 inches a year and usually falls 

in heavy showers the area is in the semiarid belt. Throughout the 

region there are many springs of good water, as well as many in 

which the water is exceedingly alkaline. The abundance of springs, 

together with the number of running streams, makes the country 

locally well watered and admirably adapted to stock raising. There 

is a large warm spring flowing good water at the head of Horse Creek, 

in sec. 35, T. 32 N., R. 86 W.; hot water rich in mineral salts issues 

from the gorge in the banks of North Platte River just above Alcova; 

and a big spring of excellent water in sec. 15, T. 32 N., R. 81 W., is 

used to irrigate about 1,000 acres of the Bessemer flats. The Big 

Sulphur Springs, in sec. 5, T. 38 N., R. 83 W., are locally well known. 

There is also warm water issuing from the sides of Beaver Gorge, 

about 4 miles, above Hailey, in T. 30 N., R. 97 W. The Warm 

Springs, near the center of T. 29 'N., R. 95 W., and Happy Springs, 

in the southeast corner of the same township, are valuable. Dams 

are built'by ranchers in the dry valleys to pond the run-off of heavy 

showers and thus make it available for stock. This practice is 

followed also by oil companies to obtain water for drilling operations. 

At times, however, water for drilling must be hauled or piped from 

some distant creek or spring.

All the deep wells in this area have found artesian water in the 

sandstones. This fact and the presence of large springs indicate 

that artesian water may be obtained in many parts of the area where 

the structural and topographic conditions are favorable.

The Lower Cretaceous conglomerate is the principal water-bearing 

formation and usually furnishes a strong sulphur water. The sandstones in the other formations generally contain water in less quantity, because they are less continuous and less uniform in thickness 

and texture.

OBJECT OF THE SURVEY.

The examination of central Wyoming was undertaken to determine whether or not the region contains anticlines or other folds 

favorable for the accumulation of oil and gas and also the number 

and occurrence of oil sands. If favorable folds are present, the next 

important question is whether the oil-bearing sands are sealed below 

impervious rocks in those folds so as to hold the oil and gas or whether 

those sands have been exposed by erosion, allowing the oil and gas to 

escape.
ANTICLINES IN CENTRAL WYOMING, 237

The table facing page 238 illustrates the fact that in most of the 

Rocky Mountain oil fields the oil seeps and productive sands are 

confined chiefly to Cretaceous strata. The occurrences outside of 

the Cretaceous so far discovered have proved of minor economic 

importance.

The Wall Creek sandstone, the uppermost sandstone member of 

the Frontier formation, is the main productive sand at Salt Creek 

and the oil has a gravity of 0.82 to 0.85. Some oil having a specific 

gravity of 0.909 is obtained at Salt Creek in the Shannon sandstone 

lentil of the Steele shale, and some is also obtained in the Niobrara.1 

In the Grass Creek field the middle part of the Frontier formation 

bears oil, and along Shoshone River gas is obtained from the upper 

part of the Cleverly and some oil from sandstones in the Thermopolis 

and Mowry 2 shales but most of the oil (specific gravity 0.833) comes 

from a sandstone in the lower part of the Thermopolis shale.

At Greybull,3 in the Peay anticline, gas and a light-gravity oil 

occur in the Kimball sand of the Mowry shale and in the top of the 

Cloverly. In the Torchlight dome at Basin a light oil of 0.7955 

gravity occurs in the Peay sand of the Frontier formation, but in the 

Lamb anticline a heavy oil of 0.889 gravity occurs in the Kimball 

sand and the Peay sand, and gas occurs commercially in the Peay 

sand and in traces only in the Torchlight, Muddy, and Kimball 

sands.4

At Elk Basin gas and a light-gravity oil occur in sands (Frontier) 

of Benton age, and at Byron oil occurs in the Frontier and gas in the 

Cloverly.

At Spring Valley a light oil of 0.82 gravity occurs most abundantly 

in the Aspen shale, and to some extent a heavy oil occurs in the Bear 

River and Frontier'formations. The Wasatch produces oil at both 

Spring Valley and Labarge, but according to Veatch 5 and Schultz 6 

the Wasatch oil has migrated from the underlying Aspen shale. 

Sandstone in the Graneros shale at Moorcroft has produced the little 

oil obtained there,7 which has a specific gravity of 0.919.

At Douglas the top of the "Cloverly"- (Dakota?) produces some 

oil, and the sands (Frontier) of Benton age, both oil of gravity 0.843 

to 0.93 and gas, but most of the commercial pro-duct comes from the

1 Wegemann, C. H., The Salt Creek oil field, Natrona County, Wyo.: U. S. Geol. Survey Bull. 452, pp. 

37-83,1911.

2 Hewett, D. F., The Shoshone Eiver section, Wyo.: U. S. Geol. Survey Bull. 541, pp. 89-113,1914.

8 Hintze, F. F., Basin and Greybull oil and gas fields: Wyoming State Geologist's Office Bull. 10; p. 45, 

1914 [1915].

« Lupton, C. T., Oil and gas near Basin, Big Horn County, Wyo.: U. S. Geol. Survey Bull. 621, pp. 

157-190,1916.

& Veatch, A. C., Geography and geology of a portion of southwestern Wyoming, with special reference 

to coal and oil: U. S. Geol. Survey Prof. Paper 56, p. 158,1907.

8 Schultz, A. R., The Labarge oil field, central Uinta County, Wyo.: U. S. Geol. Survey Bull. 340, 

p. 364,1908.

i Barnett,V. H., The Moorcroft oil field and Big Muddy dome, Wyo.: U. S. Geol. Survey Bull. 581, 

pp. 83-117,1914.
238 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART II.

White River formation. According to Barnett, 1 however, the gas 

and oil obtained from the White River has probably been derived 

from the underlying beds of Benton age or from the "Cloverly" and * 

is secondary in the White River.

At Lander, in the Big Popo Agie field, the oil at the Washakie oil 

spring and in the Plunkett well and other wells near by in the north 

end of the anticline is derived from the Mowry shale.2 It has^a 

gravity of 0.812. The heavy dark-brown oil (specific gravity 0.9+ ) 

comes from the Embar (Pennsylvanian to Bower Triassic) and Chugwater (Triassic) formations.

From this brief summary it is evident that the best oil (specific 

gravity 0.7955 to 0.856, or 45.98° to 33.5° Baume) produced in paying 

quantities in the Wyoming fields is obtained from the Cretaceous 

rocks, and chiefly from beds of Colorado age, though much comes 

from beds of Montana age. A small quantity of oil of lower grade 

(specific gravity 0.9198 to 0.9091, 22.2° to 24° Baume) comes from 

the Embar beds.

As the Lander field, in which the only notable quantity of oil comes 

from the Embar formation, joins on the west the area treated in this 

report, it seems reasonable to consider carefully any anticline or 

dome in this area in which that formation is sealed beneath impervious rocks and within reach of the drill. Any anticline or dome 

where the important oil-bearing formations of the Cretaceous are 

closed beneath thick beds of shale should be considered still more 

carefully.

The accumulation of oil and gas in all the productive fields of 

Wyoming, except Spring Valley and Douglas, is controlled by anticlinal folds. At Spring Valley the oil accumulates in a syncline the 

reverse fold of an anticline probably because the rocks are not saturated with water, a condition which allows the oil by force of gravity to 

seek the low places in the downfold or syncline.

In central Wyoming the wet porous sands occur between impervious 

shales. Where oil-bearing formations under such conditions have 

been folded the anticlines and domes have been found to be the 

favorable places for the retention of oil and gas, presumably because 

oil and gas, being lighter than water, are floated and forced to the 

crests of the anticlines and domes, or at least as far up as the water 

has any head. If, as is the case in many of the anticlines in central 

Wyoming, erosion has removed parts of the oil-bearing formations, 

the oil and gas have had ample chance to escape and there is little 

possibility of their retention. In such places indications of oil occur 

as seeps along the outcrop of the sandstone. Wells drilled down the

1 Barnett, V. H., The Douglas oil and gas field, Converse County, Wyo.: U. S. Geol. Survey Bull. 541, 

pp. 49-88,1914.

2 Woodruff, E. G., The Lander oil field, Fremont County, Wyo.: U. S. Geol. Survey Bull. 452, pp. 7-36, 

1911.
Sections showing occurrence of oil and gas in some of the Rocky Mountain fields. 

[Correlations approximate and sections incomplete, o., Oil; g., gas; 4-. seeps or small production of oil or gas.]

System or series.

Tertiary.

Tertiary (?).

Cretaceous.

Cretaceous(?).

Jurassic.

Triassic.

Permian.

Pennsylvanian.

Group.

Montana.

Colorado.

Spring Valley and 

Labarge.o

Wasatch. +o.

Evanston.

Adaville.

Hilliard.

Frontier, o.

Aspen, o.

Bear River, o.

Beckwith.

Twin Creek.

Grass Creek & and 

Oregon Basin.

Wasatch.

Fort Union.

Lance.

Meeteetcs.

Mesaverde.

Cody.

Frontier, o.

Mowry.

Thermopolis. g.

Cloverly.

Morrison.

Shoshone River. 6

Wasatch.

Fort Union.

Ho (Lance).

Meeteetse.

Gebo.

Colorado.

(+) 

(+)

(o.) 

(o.)

"Cloverly." g.

Morrison. g.

Sundance.

Greybull. e

Fort Union.

Do.

Montana, undifferentiated.

Eagle.

Pierre.

Basin.

Benton. 

Torchlight. 

Peay. 

(o. g.)

Cloverly. o. g. 

Greybull.

Morrison.

Basin. <J

Undifferentiated 

Fort Union and 

Lance.

Mesaverde.

Cody.

Frontier.

Torchlight. +

(+) 

Peay. +g.

Mo\vr3\ +o.

 Thermopolis. +

Cloverly.

Morrison.

Lander.<

Wind River.

Absent or concealed.

Mesaverde.

Mancos. 

(+o.)

Dakota.

Lower Cretaceous 

(?).

Morrison.

Sundance.

Chugwater. -(-o.

Embar. o.

Wyoming. /

Wasatch. +

Laramie. 

Fort Union.

Fox Hills.

Fort Pierre.

Niobrara. 

(+)

Fort Benton.

Dakota. + 

(+)

Como.

Shirley.

Triassic.

Permian. 

Carboniferous.

Central Wyoming 

(this report).

White River. +

Wind River. +?

Fort Union.

Lance.

Lewis.

Mesaverde. 

Teapot. +

Parkman.

Steele. 

Shannon.

Niobrara.

Carlile.

Frontier.

Wall Creek. + 

+ 

Peay. +

Mowry.

Thermopolis.

Dakota. +

Lower Cretaceous. 

Shale.

Conglomerate. 4-

Morrison. 4-

Sundance. +

Chugwater. +

Embar. \.

Tensleep. +

Amsden.

Salt Creek and 

Powder River, g

Fort Union.

Lance.

Fox Hills.

Pierre. 

Parkman.

Shannon, o.

Niobrara. o.

Benton. 

Wall Creek, o.

Mowry. 4-

Dakota(?). +

Morrison. +.

Sundance. +.

Douglas.^

White River, o.g.

Fort Union.

Lance.

Fox Hills.

Pierre. 

Parkman (?).

Shannon (?). +

Niobrara.

Benton. +o. g. 

Wall Creek (?).

Mowry.

(0?)

"Cloverly." o. -+ 

Morrison.

Sundance.

Chugwater.

Forelle (?). 

Satanfca (?). + 

Casper.

Moorcroft and Newcastle, t

Fox Hills.

Pierre.

Niobrara.

Carlile.

Greenhorn.

Graneros. 

Mowry. o.

Dakota. +

Fuson. +.

Lakota.

Morrison.

Sundance.

Boulder, Colo. j

Fox Hills.

Pierre. 

Hygiene, o. g.

(0.)

Niobrara. o.

Benton. o.?

Dakota.

Morrison.

LyMns.

Lyons. 

Fountain.

Florence, Colo.t

Laramie (?).

Trinidad. (?).

Pierre. 

(o.)

Niobrara.

Carlile.

Greenhorn.

Graneros.

"Dakota." 4-

Morrison. +

o Veatch, A. C., Geography and geology of a portion of southwestern Wyoming, with special reference to coal and oil: U. S. Geol. Survey Prof. Paper 

56, pp. 157-158,1907. Schultz, A. R., The Labarge oil field, central Uinta County, Wyo.: U. S. Geol. Survey Bull. 340. p. 364,1908.

J> Hewett, D. F., The Shoshone River section, Wyo.: U. S. Geol. Survey Bull. 541, pp. 89-113,1914, and unpublished data.

c Hintze, F. F., Basin and Greybull oil and gas fields: Wyoming State Geologist's Office Bull. 10, p. 40,1914 [1915].

d Lupton, C. T., Oil and gas near Basin, Big Horn County, Wyo.: U. S. Geol. Survey Bull. 621, pp. 157-190,1916.

e Woodruff, E. G., The Lander oil field, Fremont County, Wyo.: U. S. Geol. Survey Bull. 452,1911.

/ Knight, w. C., A preliminary report on the artesian basins of Wyoming: Wyoming Univ. Exper. Sta. Bull. 45,1900. Knight, W. C.. and Slosson, 

E. E., The Dutton, Rattlesnake, Arago, Oil Mountain, and Powder River oil fields :_Wyoming Univ. School of Mines, Petroleum ser., Bull. 4,1901.

43768° Bull. 641 17. (To face page 238.) ~~

g Wegemann, C. H., The Salt Creek oil field, Natrona County, Wyo.: U. S. Geol. Survey Bull. 452, pp. 37-83,1911; The Powder River ofl field, 

Wyo.: U. S. Geol. Survey Bull. 471, pp. 56-75,1912.

ft Barnett, V. H., The Douglas on and gas field, Converse County, Wyo.: U. S. Geol. Survey Bull. 541, pp. 49-88,1914.

< Barnett, V. H., The Moorcroft ofl field and Big Muddy dome, Wyo.: U. S. Geol. Survey Bull. 581. pp. 83-117,1914. Darton. N. H., Preliminary 

report on the geology and underground water resources of the central Great Plains: U. S. Geol. Survey Prof. Paper 32, pp. 334, 364,379-388,1905.

/ Fenneman, N. M., Geology of the Boulder district, Colo.: U. S. Geol. Survey Bull. 265. pp. 76-98,1905.

6 Washburne, C. W., The Florence oil field, Colo.: U. S. Geol. Survey Bull. 381, pp. 517-544,1910.
ANTICLINES IN CENTRAL WYOMING. 239

dip from such outcrops penetrate these beds and commonly obtain 

water with a few drops of oil. This was true of the Oil City, the 

Northwestern, the Button "Basin," and the Western States wells. 

Under these conditions it is clearly evident that anticlines having 

the oil-bearing sandstones completely sealed beneath impervious beds 

should be first chosen for prospecting.

The accompanying table summarizes the available information as 

to the geologic position of the oil and gas bearing beds in the Wyoming 

and some adjacent fields.

HISTORY OF PROSPECTING.

The presence of oil seeps in this region was first described by 

Aughey in 1886.1 Some of these seeps, however, had been known 

since the days when the first emigrants passed through the region 

going to Oregon and California. It is reported that Cimineau,2 a 

French trapper, and others sold lubricants to the caravans from the 

oil spring in sec. 28, T. 33 N., R. 82 W., 1 mile south of Poison 

Spider Creek, near Oil Mountain.

One of the first wells sunk in the area covered by this report was 

drilled in 1886 on Poison Spider Creek, in sec. 4, T. 32 N., R. 86 W., 

at Oil City, by the Colorado & Wyoming Land & Oil Co. Under the 

management of George L. Aggers, of Douglas, Wyo., this well was 

put down to a depth of 1,130 feet and at a depth of 500 feet struck 

130 feet of sandstone, which carried a little oil and water.3

The two wells drilled by the Wyoming Central Association in the 

early eighties near the head of Powder River to depths of 700 and 

900 feet were water wells with only a slight showing of oil.4 It is 

thought that the first well drilled prior to 1886 near the SW. £ sec. 34, 

T. 34 N., R. 88 W., to a depth of nearly 1,000 feet, which obtained a 

slight amount of oil, gas, and much water, was one of the Wyoming 

Central Association wells.5 The Northwestern Oil Co.'s well, which 

according to Knight 6 was drilled about the same time and a short 

distance northwest of the Wyoming Central Association wells to a 

depth of about 500 feet, struck no appreciable quantity of oil. When 

visited in 1915 a well near the west quarter corner of sec. 20, T. 33 N., 

R. 87 W., was giving off a small quantity of gas and a few drops of 

oil. There was only enough dark, thick, asphaltic oil on the water 

which rose to the top of the casing to furnish a small sample. No 

data seem to be available concerning the Moffat well, on Lovett 

Creek.

1 Aughey, Samuel, Wyoming Territorial Geologist Ann. Kept., 18S6, pp. 113-187.

2 See U. S. Geol. Survey Bull. 612, p. 62,1915.

s Ricketts, L. D., Wyoming Territorial Geologist Ann. Kept., 1888, pp. 22-36. 

< Idem, p. 35.

s Aughey, Samuel, op. cit. Knight, W. C., Wyoming Univ. School of Mines, Petroleum series, Bull. 4, 

p. 28, map, 1901. 

" Knight, W. C., idem, pp. 21-26.
240 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART It

Nearly contemporaneous with the sinking of the Northwestern 

well was the drilling of the Guthery well, in sec. 18, T. 33 N., R. 82 W., 

on Poison Spider Creek. This well was sunk to a depth of about 

1,000 feet, and a flow of strong sulphur water was encountered, 

presumably in the Lower Cretaceous conglomerate. It is reported 

that some oil was found, but that the quantity was so insignificant 

that oil was hauled from the wells at Salt Creek and the place "salted." 

At the time of-visit a small stream of water surcharged with hydrogen 

sulphide gas flowed from the casing, but there was no indication of oil.

It is said that a shallow well was drilled farther down Poison 

Spider Creek, just above the Goose Egg ranch, and that the tools were 

purposely lost in it.

The well near North Platte River, 2 miles above Alcova, struck 

water but no oil. Its location is in the syncline between the monoclinal fold to the west and the Alcova or Hot Springs arch to the east.

Scattered throughout the area are assessment pits of the oilprospecting days of the eighties, and it is almost impossible to ride 

over the area for any considerable length of time without seeing some 

of them. It is reported that a small quantity of oil was collected in 

some of these pits near the Horse Creek dome, in sees. 26, 27, and 34, 

T. 32 N., R. 86 W. At the oil spring near the north end of Oil 

Mountain there are two pits. The western one of these, which was 

dug to a depth of 10 feet or so, has nearly filled up by caving and when, 

visited contained about 3 feet of water covered with a thin scum of 

thick, dark oil. It is from this place that a small quantity of oil was 

supplied to the travelers who trailed through the region in the days 

of 1849.

After the era of assessment pits and shallow wells very little 

prospecting was done until the development of the Salt Creek and 

Bighorn Basin oil fields revived interest in oil through the area. 

The first operation was the sinking of a test well by the Midwest 

Oil Co. on the Castle Creek fold, near the east quarter corner of sec. 

31, T. 38 N., R. 80 W., to a depth of about 2,000 feet. Some gas was 

found in the shale above the Wall Creek sand, and from the sand 

water rose nearly to the top of the casing. A little gas was escaping from the well when it was visited late in the fall of 1914.

A well completed in the summer of 1913 at the north end of the 

Button anticline was started near the contact of the Niobrara and 

Steele shales, in the NW. { sec. 34, T. 34 N., R. 90 W. It was 

drilled to a depth of about 1,060 feet, and when visited it was giving 

off gas in small quantities, and thick, dark oil stood on the water 

about 20 feet below the top of the casing.

In the summer of 1913 the Ohio Oil Co. drilled two holes, one on 

Poison Spider Creek in the SE. i SE. \ sec. 18, T. 33 N., R. 82 W., 

and the other in the NE. £ NE. $ sec. 2, T. 33 N., R. 95 W.§, near
ANTICLINES IN CENTRAL WYOMING. 241

Alkali Butte in the "Riverton oil field." In the well on Poison 

Spider Creek the Dakota sandstone at a depth of 641 feet contained 

some black oil. The Lower Cretaceous conglomerate at 785 feet 

carried water and a little oil, and the Morrison formation showed 

signs of oil. The well was sunk to a depth of 2,855 feet, and the last 

15 feet was in the Tensleep sandstone, which contained artesian 

water. The other well, near Alkali Butte, encountered no water 

anywhere.in the 2,945-foot hole, which was probably entirely in the 

Steele shale. A trace of gas and oil was obtained in a 7-foot bed of 

soft sand at a depth of 177 feet.

The Holmes well, in sec. 3, T. 36 N.; R. 82 Wv was the first one 

located on the North Casper Creek anticline. This well, which is 

about 500 feet west of the contact of the Niobrara and Steele shales, 

is 2 miles west of the axis of the anticline and was drilled to a depth 

of 1,170 feet. It penetrated 15 feet into the Wall Creek sand, from 

which water rose within 100 feet of the top of the casing.

The Fitzhugh well, 1^ miles north of the Holmes well, was started 

June 19 and finished August 24, 1913. It is near the west quarter 

corner of sec. 26, T. 37 N., R. 82 W., about 800 feet east of the upper 

contact of the Niobrara shale. The locator in the selection of this 

site seems not to have considered duly the record of the Holmes 

well and the form of the anticline, otherwise his location would not 

have been so near the contact of the Steele and Niobrara shales, a 

position on nearly the same structure contour as that of the Holmes 

well. The two logs are similar. In the Fitzhugh well water was 

struck in the Wall Creek sand at a depth of 1,000 feet, and the well 

was abandoned at 1,642 feet.

The Monongahela Oil Co. commenced operations in July, 1913, in 

the SE. | sec. 9, T. 33 N., R. 81 W., just west of Twelvemile Spring, 

in the Emigrant Gap anticline. At a depth of 240 feet a flow of 

sulphur water was struck in the Lower Cretaceous conglomerate. 

This is the only well so far drilled near the axis of the anticline. The 

dry holes on Casper Creek, in Tps. 33 and 34 N., R. 80 W., are far 

down the east flank.

The Western States Oil Co.'s well, started hi the summer of 1913 

near^the center of T. 33 N., R. 94 W., in the so-called Riverton oil 

field, is in the syncline between the Conant Creek and Alkali Butte 

anticlines. The location is on the Steele shale, and, according to 

reports, the Wall Creek sand, at a depth of 1,300 feet, showed some 

trace of oil. The well was not completed at the time of the field 

examination.

The Franco-American well, in the SE. i SE. £ sec. 16, T. 34 N., 

R. 87 W., is on the Wallace Creek dome (?). This well was put down 

about 600 feet during the summer of 1913, but was idle when the area 

was mapped. Later it was sunk to a depth of more than 2,000 feet,
242 CONTRIBUTIONS TO ECONOMIC GEOLOCA, 1916, PART II.

probably entirely in the Fort Union and Lance formations, but 

encountered no oil.

The Toltec Oil Co. late in the fall of 1913 put down a well in sec. 11, 

T. 37 N., R. 85 W., on the Cottonwood Creek anticline, at the south 

end of the Bighorn Mountains. It was free from water down to a 

depth of 915 feet, except small quantities at 125 and 458 feet, but at 

915 feet warm and highly charged sulphur water, presumably from 

the Lower Cretaceous conglomerate, flowed in large quantities over 

the top of the casing. The well was abandoned at a depth of 990 

feet without obtaining oil.

In September and October, 1914, William M. Fitzhugh and his 

associates drilled a 1,975-foot dry hole in the NW. £ sec. 36, T. 37 N., 

R. 82 W., on the North Casper Creek anticline. They struck water 

in the Wall Creek sand at a depth of 440 feet and in the Peay sand at 

1,045 feet, but the Dakota (?) sandstone at 1,675 feet was dry. The 

Lower Cretaceous conglomerate at a depth of 1,769 feet and also the 

Morrison formation carried water. Free carbon, bitumen, paraffin, and 

some carbonic gas were found in dark-blue shale at 1,560 and 1,679 feet. 

This well is located near the axis of the anticline about 2 miles north of 

its crest and with the other wells drilled near by has shown that the pool 

of oil or gas, if any exists in this anticline, is not greater than 1£ by 4£ 

miles in extent, which is almost the size of the Salt Creek field.

The Casper Oil Co. in the fall of 1915 started a well in sec. 28, T. 

38 N., R. 81 W., about a mile below the 33 Mile ranch on Castle 

Creek. This well was dry for 1,900 feet.

Aside from these wells, drilled by standard outfits, numerous 

assessment holes have been put down with Star rigs, none of which 

have attained sufficient depth to be of value. The prospecting of 

this sort that has been done along the eastern flank of the Rattlesnake 

Mountains is a good example of waste of time and money.

OIL-BEARING FORMATIONS.

Many of the formations in this field, from the Cambrian to the 

Oligocene, contain sandstone members or strata, but only those which 

contain traces of oil or produce oil and gas in this or near-by fields 

will be described. The formations may be seen hi the different anticlines of the field, and they will be taken up in stratigraphic order, 

the lowest one first, as shown in the columnar section on Plate XXIII. 

That some of the shales contain oil pools is not considered probable, 

although it is recognized that oil may be present in shale here, as it 

is in some other Rocky Mountain fields.

Cambrian and pre-Cambrian formations. The Cambrian and preCambrian beds, according to oral reports, are saturated with oil near 

Copper Mountain, on the south side of the Owl Creek Mountains, 

near T. 39 N., R. 92 W., about 40 miles northwest of the Rattlesnake
ANTICLINES IN CENTRAL WYOMING. 243

Mountains. The Wind River formation (Eocene), which overlies the 

Cambrian at this locality, is also said to snow traces of oil. The 

locality was not examined, but the information is considered reliable. 

No indications of oil, however, were observed in the Cambrian or preCambrian in the area covered by this paper.1

Tensleep sandstone. The Tensleep sandstone, of Pennsylvanian 

age, is the lowest formation which shows signs of oil in this field. It 

is approximately 200 feet thick in the Rattlesnake Mountains. An 

exposure of a few square rods in the SW. \ sec. 13, T. 33 N., R. 90 

W., in the Dutton anticline, contains some oil, but so far as observed 

none escapes. At all other localities where the formation was examined it is barren. The rock is a medium -grained, highly cross-bedded, 

firmly cemented quartz sandstone, which is of sufficiently open texture to allow the free circulation of water, as shown by the Ohio 

well, on Poison Spider Creek.

Embar formation. No indications of oil were seen in the Embar 

formation (Pennsylvanian, Permian, and Triassic), but in the Lander 

field,2 which adjoins this area on the northwest, it is one of the main 

oil-producing formations. The Embar overlies the Tensleep sandstone and is composed of 225 feet or more of light-gray fossiliferous 

limestone, shale, chert, and beds of phosphate. It is typically developed in the western part of the area, where it is equivalent to the 

Park City and Dinwoody formations, but in the eastern part it is of 

an entirely different character, consisting mostly of red shale with 

some limestone, fossiliferous red and gray chert, and gypsum. The 

Embar in this field contains no thick beds of sandstone. It was reported that the well of the Pine Dome Oil Co. obtained its flow of gas 

from the Embar, but it is fully as probable that the gas came from 

the Tensleep sandstone.

Chugwater, Sundance, and Morrison formations. Along the east 

flank of the Rattlesnake Mountains north of Garfield Peak there are 

places where the sandstones in the upper (Triassic) part of the Chugwater, the Sundance (Jurassic), and especially the Morrison (Cretaceous ?) formations show signs of oil. Oil seeps from the Sundance 

and Morrison formations in the unproductive Powder River oil field,3 

which is adjacent to this field on the north. These formations contain thin and thick sandstones that in favorable folds would serve 

as reservoirs for oil. The formations present their usual characteristics. The Chugwater consists essentially of 1,000 feet of brickred unfossiliferous sandy micaceous shale, thin-bedded sandstone,

1 Since this was written the indications of oil in this locality have been described as petroleum in granite 

by L. W. Trumbull (Wyoming State Geologist's Office, Sci. ser., Bull. 1, pp. 4-7,1916).

2 Woodruff, E. G., The Lander oil field: U. S. Geol. Survey Bull. 452, p. 27,1911. Jamison, C. E., Geology 

and mineral resources of a portion of Fremont County, Wyo.: Wyoming Geol. Survey Bull. 2, pp. 33-34, 

1911.

s Wegemann, C. H., The Powder River oil field, Wyo.: U. S. Geol. Survey Bull. 471, p. 71,1912.
244 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART H.

and gypsum. A thin limestone occurs near the top in the eastern 

part of the field, but in the western part this same limestone is near 

the middle of the formation. The Sundance consists of about 300 

feet of marine olive-green shale and highly fossiliferous gray limestone. The Morrison consists essentially of 250 feet of fresh-water 

variegated shale and sandstone.

Lower Cretaceous conglomerate. The next higher oil-bearing formation is the conglomerate assigned to the Lower Cretaceous. This is 

the lower part of the "Dakota" formation mentioned by Knight 1 

as being the most promising oil-bearing formation of the field. It 

is the "basal conglomeratic sandstone of the Cloverly formation of 

the Bighorn Mountains, the lower member of the Cloverly formation 

of the Basin and Greybull oil and gas fields,2 and the Dakota (?) of 

the Salt Creek field.3 It is identical with the conglomerate described 

as of Lower Cretaceous age (?) in the Lander field.4 This formation 

contains dark-colored, well-rounded chert pebbles, commonly about 

the size of small marbles but reaching a maximum diameter of 1-| 

inches, firmly cemented. Usually the cement is silica, but in some 

places it is lime. The coarse basal conglomerate that constitutes the 

lower half of the formation grades upward into a slightly conglomeratic sandstone and the whole attains a thickness of about 60 feet. 

It varies little from this thickness throughout the eastern part of 

the area, though in the Conant Creek anticline it is only 8 feet thick. 

The formation where upturned forms small hogbacks, a feature which, 

with the lithologic character, makes its identification easy.

Though the conglomerate is mentioned by Knight 5 as showing 

traces of oil in the Dutton "anticline," none were noticed in it there 

or in the other exposures of the conglomerate, except along the 

Rattlesnake Mountains. It is probably the source of the oil at the 

seep in sec. 28, T. 33 N., R. 82 W., at the north end of Oil Mountain. 

Small quantities of dark, thick oil ooze from it near the Lew Smith 

Spring, at the head of Horse Creek, in sec. 26, T. 32 N., R. 86 W., on 

the southwest side of the Rattlesnake Mountains. A few sections 

of land have been patented as oil placer land about 2 miles south of 

Oil City because dark asphaltic oil seeps from the conglomerate beds 

in that locality. Northwest of Oil City and south of Garfield Peak 

the conglomerate contains little if any oil, but in places on Wallace 

Creek and on the small creeks near by it is saturated with dark 

asphaltic oil. The light volatile parts have evaporated from the oil

1 Knight, W. C., Wyoming Univ. School of Mines, Petroleum ser., Bull. 4, pp. 17-19,1901.

2 Hintze, F. F., jr., The Basin and Greybull oil and gas fields, Big Horn County, "Wyo.: "Wyoming State 

Geologist's Office Bull. 10, pp. 16-17,1914.

»Wegemann, C. H., The Salt Creek oil field, Natrona County, Wyo.: U. S. Geol. Survey Bull. 452, p. 44, 

1911.

* Woodruff, E. G., The Lander oil field, Fremont County, Wyo.: U. S. Geol. Survey Bull. 452, pp. 18-19, 

1911. .

6 Knight, W. C., op. cit., pp. 17-19.
ANTICLINES IN CENTRAL WYOMING. . 245

that seeps here, and the heavy dark residue, mixed with soil and 

dead vegetation, has accumulated on the creek bottoms to a thickness 

of a foot or more and covers many square rods. This deposit is 

used locally for fuel, chiefly for engines drilling prospect holes. Strong 

sulphur water was found in the conglomerate in the Ohio well, on 

Poison Spider Creek, and in the Guthery, Monongahela, and Toltec 

wells, and similar water issues from the conglomerate in sec. 15, T. 

33 N., R. 81 W. The Ohio and Guthery wells struck traces of oil in 

the conglomerate.

Dakota sandstone. Directly below the Thermopolis shale and from 

100 to 350 feet above the Lower Cretaceous conglomerate is a finegrained brown to gray quartzitic sandstone, ranging in thickness from 

a few inches to a maximum of 60 feet, as observed at the south end 

of the Emigrant Gap anticline. This sandstone is considered the 

same as the Dakota of the Lander country.1 It is the upper member 

of the Cloverly formation of some authors, but is here referred to 

the Dakota (Upper Cretaceous). It may correspond to the Greybull 

sand of the Bighorn Basin. 2 This sandstone contains no oil at the 

south end of the Rattlesnake Mountains or near Garfield Peak, but 

at numerous places on Wallace Creek and the creeks to the north it 

is saturated with dark asphaltic oil and, with the Lower Cretaceous 

conglomerate, furnishes the asphaltum found in that district. The 

Dakota shows no trace of oil throughout the rest of the field. This 

sandstone is so variable in thickness and so unfavorably situated in 

most of the anticlines that it is considered unimportant as a reservoir for oil unless it may be in the same anticlines as those mentioned 

in connection with the Lower Cretaceous conglomerate.

Mowry shale. From 100 to 300 feet above the Dakota sandstone 

is the Mowry shale, of Upper Cretaceous age, a hard, fissile dark 

shale, weathering white, which contains abundant fish scales, vertebrae, and fins, but in which no complete skeletons have been found. 

The Mowry shale, which forms pronounced pine-bearing ridges in 

most of the anticlines, is normally about 300 feet thick and is an 

exceptionally good key rock. It is in most localities immediately 

.overlain by a bed of bentonite. No traces of oil were seen oozing 

from this formation, but it produces oil in the Bighorn Basin,2 at 

Lander,3 and at Spring Valley 4 and is the probable source of the oil

i Woodruff, E. G., op. cit., pp. 18-19.

2 Lupton, C. T., Oil and gas near Basin, Big Horn County, Wyo.: U. S. Geol. Survey Bull. 621, pp. 

157-190,1916.

s Woodruff, E. G., The Lander oilfield, Fremont County, Wyo.: U. S. Geol. Survey Bull. 452, p. 27 1911.

4 Voatch, A. C., Geography and geology of a portion of southwestern Wyoming, with special reference 

to coal and oil: U. S. Geol. Survey Prof. Paper 56, p. 158,1907.
246 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART II.

in the Wasatch formation at Labarge. 1 Oil is reported to occur in 

the Mowry shale in the unproductive Powder River field.2

One of two samples of the Mowry shale tested by distillation 

yielded about 2 gallons of oil to the ton and the other a mere trace. 

The latter contained the greater quantity of fish remains. The tests 

were made in order to throw light on the possible origin of the Wyoming oil, but the results were unsatisfactory.

Frontier formation. The Mowry shale is overlain by shale and 

sandstone that are referred to the Frontier formation, of Upper 

Cretaceous age. The sandstones, of which there are three distinct 

divisions corresponding in ascending order to the Peay, an intermediate sand, and the Wall Creek, are of medium to fine grain, gray, 

somewhat massively bedded, and from 20 to 200 feet thick. The 

formation attains a maximum thickness of 1,000 feet. The intervening shale, which makes up more than half of the formation, is 

dark and sandy. The lowest sandstone member, corresponding to 

the Peay, is persistent and characterized by large brown concretions, especially in the Emigrant Gap and Oil Mountain anticlines 

and the Pine dome. The middle sandstone is commonly characterized by small black chert pebbles about the size of peas, which 

usually distinguish it from the other two sandstones, though in a 

few places the Wall Creek contains similar pebbles. The upper or 

Wall Creek sand is the main productive oil sand in the Salt Creek 

field, 25 miles northeast of the North Casper Creek anticline,3 but 

the Peay and Torchlight are important producing sands in the Bighorn Basin.4 The Wall Creek sandstone may correspond to the 

Torchlight, as shown by Hintze, for it is stratigraphically at about 

the same position.

Thick, black oil oozes from the sandstones of the Frontier in the 

Alkali Butte anticline, and traces of oil were found in them along 

the Rattlesnake Mountains,

Teapot sandstone member of the Mesaverde formation. The highest 

Cretaceous sand in which oil was observed is the Teapot sandstone 

member of the Mesaverde formation (Upper Cretaceous), a mediumtextured white sandstone from 90 to 200 feet thick. This sandstone 

has a wide distribution in Wyoming and is the upper part of the 

Mesaverde. It is spoken of as the "sandstone forming Little Pine

1 Schultz, A. R., The Labarge oil field, central Uinta County, Wyo.: U. S. Geol. Survey Bull. 340, pp. 

367-371,1908. Trumbull, L. W., Prospective oil fields at Upton, Buck Creek, Rattlesnake Mountains, and 

Labarge: Wyoming State Geologist's Office Bull. 5, pp. 14-15,1913.

2 Wegemann, C. H., The Powder River oil field, Wyo.: U. S. Geol. Survey Bull. 471, p. 71,1912.

s Wegemann, C. H., The Salt Creek oil field, Natrona County, Wyo.: U. S. Geol. Survey Bull. 452. pp. 

71-75,1911.

4 Washburne, C. W., Gas fields of the Bighorn Basin, Wyo.: U. S. Geol. Survey Bull. 340, pp. 348-363, 

1908. Hintze, F. F., jr., The Basin and Greybull oil and gas fields, Big Horn County, Wyo.: Wyoming 

State Geologist's Office Bull. 10, pp. 41-47,1914. Hewett, D. F., The Shoshone River section, Wyo.: U. S. 

Geol. Survey Bull. 541, p. 65,1914,
ANTICLINES IN CENTRAL WYOMING. 247

Ridge" in the Salt Creek field and is the Teapot sandstone near 

Casper as described by Barnett.1 It is the prominent sandstone 

that forms the striking white wall across Tps. 32 and 33 N., Rs. 82 

and 83 W., southeast of the F L ranch. This sandstone, forming a 

low ridge locally known as Phayles Reef near the Marquis ranch, 

along the east flank of the Rattlesnake Mountains in sees. 4, 5, and 9, 

T. 33 N., R. 87 W., is highly saturated with oil. This sandstone at 

Phayles Reef is probably the one conditionally placed by Knight 2 

in the Fox Hills and noted by him as saturated with oil. In prospecting for oil in the dome on Wallace Creek drilling should go at 

least deep enough to test this sand for oil.

Wind River formation. The Wind River formation, of Eocene age, 

consists essentially of soft variegated shale, coarse brown sandstone, 

arkose, and both fine and coarse conglomerate. These beds are for the 

most part nearly flat-lying or tilted at very small angles and unconf ormably overlie.all the older formations, including the Cambrian. No 

oil seeps were noted in the Wind River, but some are mentioned by 

Knight as occurring west of the Button anticline.3 The Wind River 

is reported to show traces of oil south of the Owl Creek Mountains 

in T. 39 N., R. 92 W. Oil is obtained in small quantities from beds 

of nearly the same age at Spring Valley 4 and Labarge,5 in southwestern Wyoming. It is probable that in all these places the oil has 

escaped from the underlying Cretaceous sands into the overlying 

beds. As the Wind River in places overlies the upturned Cretaceous 

oil-bearing sands, it is possible that in some of these places oil may 

be found in the Wind River, but this seems a remote possibility, and 

no commercial pools are to be expected.

White River formation. The White River formation of Oligocene 

age, is composed essentially of. loosely cemented light-colored fine 

and coarse sand, arkose, and conglomerate. Volcanic material, in 

the form of pebbles and single grains, is present throughout the 

formation. Red color is generally absent in the formation, but light 

green and buff are plentiful and even white rocks are not uncommon. 

The White River is nearly flat lying and rests unconformably on all 

formations from the pre-Cambrian granite of the Granite Mountains 

to the Steele shale and also the Wind River.

Small quantities of oil ooze from beds considered of White River 

age at the Lew Smith oil spring, in sec. 26, T. 32 N., R. 86 W., in the

1 Barnett, V. H., Possibilities of oil in the Big Muddy dome, Converse and Natrona counties, Wyo.: 

U. S. Geol. Survey Bull. 581, pp. 113-114,1915.

2 Knight, W. C., Wyoming Univ. School of Mines, Petroleum ser., Bull. 4, pp. 28-29,1901.

3 Idem, p. 16.

4 Veatch, A. C., Geography and geology of a portion of southwestern Wyoming, with special reference to 

coal and oil: U. S. Geol. Survey Prof. Paper 56, pp. 1C, 139,141,143-144,151,1907.

6 Schultz, A.R., Geology and geography of a portion of Lincoln County, Wyo.: U. S. Geol. Survey Bull. 

543, p. 117,1914.
248 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART II.

Rattlesnake Mountains, but the oil probably comes from the underlying Lower Cretaceous conglomerate or the Dakota sandstone. A 

little asphaltic material occurs in rhyolitic bombs in the upper part of 

the White River formation on the Sweetwater escarpment in sees. 10 

and 11, T. 32 N., R. 94 W.

It is possible that where this formation lies on the upturned 

Cretaceous oil sands, as in the area between Alcova and the Rattlesnake Mountains or at the south end of the Rattlesnake Mountains, 

it may contain small quantities of oil. Commercial pools, it is 

believed, are not to be expected in the White River in this field. 

Small pools, however, occur in beds of the same age at Douglas.1

ANTICLINES 2 AND OTHER FOLDS.

GENERAL FEATURES.

In comparatively recent geologic time, the outer crust of the earth 

in all parts of Wyoming, which once lay in great nearly level sheets 

or beds of shale, sandstone, and limestone, was bent and wrinkled 

into great and small anticlinal and synclinal folds. These folds or 

earth waves may be likened to the billows and waves on water or to 

the wrinkles on merino sheep. They are elongated, and some are much 

higher and larger than others. Some of the high rock folds in 

Wyoming are the giant anticlines of the Laramie, Granite, Wind 

River, Owl Creek, and Bighorn mountains. The Powder River, 

Green River, Wind River, and Bighorn basins are giant synclines. 

These great folds are not arranged in any definite order, as their axes 

trend in several directions.

The small anticlines described in this report are situated upon the 

sides of the giant folds or between them. They are elongated and 

compressed, their axes, which nearly" parallel one another, trend in a 

northwesterly direction (see PI. XXIII), and they are broken here 

and there by small faults. The axes of the small anticlines pitch 

either in one direction for example, those of the anticlines that 

project as spurs from the giant folds or in two directions for example, those of the assemblage of more or less simple anticlines in the 

lowland area between the Laramie and Bighorn mountains.

^arnett, V. H., The Douglas oil and gas field, Converse County, Wyo.: U. S. Geol. Survey Bull. 541, 

pp. 48-88,1914.

8 The term anticline is used here for brevity of description to include bowed-up folds that have two limbs 

that is, sides in which the same strata dip in opposite directions from the axis. According to Willis (U. S. 

Geol. Survey Thirteenth Ann. Kept., pt. 2, p. 200,1893), "the line or area of meeting of the sides is the 

axial region, the crest or crown of an anticline, the base or bottom of a syncline," and it is commonly 

called simply the axis. Generally the anticline is developed in nearly flat-lying rocks, and its axis pitches 

toward its two extremities, but in places the anticline or syncline is developed on the upturned rocks that 

form the rim of some large structural basin, and in that case the axis may pitch in only one direction. For 

convenience of description, anticlines and synclines developed on tilted beds will be called slope anticlines and slope synclines. Willis says: "When the limbs of an anticline are wide open downward further shortening of the zone of strata is possible by lessening of this angle; such may be called an open 

fold."
ANTICLINES IN CENTRAL WYOMING. 249

»

While the great, nearly level sheets of shale, sandstone (in part 

oil bearing), and limestone were being bent into anticlines, they were 

also being worn away from the crests of the anticlines, mostly by 

water and wind, and the detrital material so derived was in the main 

deposited as layers of mud and sand in the troughs of the giant 

synclines. These flat-lying layers filled the synclines and reached far 

up on the sides of the giant anticlines, nearly covering the small 

anticlines, some of which even now are largely hidden by the flatlying beds. All the giant anticlines and many of the small ones have 

been truncated or worn down so deeply that in many places the oilbearing sands have been exposed, allowing the oil to escape.

SWEETWATER ANTICLINE. 1

The Granite Mountains, viewed broadly, are in the middle of a great 

upfold, which will be referred to as the Sweetwater anticline. 

Although dominantly anticlinal, it is by no means a single fold 

but is in reality an assemblage of folds that make up one giant, 

deeply eroded compound anticline. The nucleus of granite in the 

Sweetwater Valley and Granite Mountains is surrounded by strata 

which dip steeply in some places and slightly in others and which 

now represent the outcropping, worn edges of formations that probably once extended over the anticline. The Sweetwater anticline 

is approximately 50 miles wide by 120 miles long, and the granite 

nucleus is about 25 by 100 miles. The south limb and east end of 

the anticline are not represented on Plate XXIII. At the west end 

there is an apparent continuation of the great upfold in the anticline 

of Sheep Mountain in Tps. 30 and 31 N., Rs. 96, 97, and 98 W. The 

trend of the Sweetwater anticline is almost due east, and in this 

respect it is like, the giant anticlines of the Uinta Mountains, in the 

northeastern part of Utah, and the Owl Creek Mountains, in the northcentral part of Wyoming, but its trend is not in harmony with the 

dominant northwesterly anticlines in the remainder of Wyoming.

The widely separated limbs are represented now by such folded 

rocks as those in the Rattlesnake Mountains and at Alkali Butte, 

on the north side, and those at Happy Springs and Green Mountain, 

on the south. Large faults occur along the south limb of the anticline, and in places, especially at Green Mountain, the formations 

are overturned. These-folds and faults about the sides of the Sweetwater anticline and much of the granite nucleus are now covered by 

flat-lying strata, either light-colored or variegated, that hide for the 

most part the detail of the anticline.

i Hayden, F. V., Exploration of the Yellowstone and Missouri rivers, pp. 77-78, U. S. War Dept., 1869: 

U. S. Geol. Survey Terr. Fourth Ann. Kept., pp. 24-35, 1872. Endlich, F.M., Report on geology of th« 

Sweetwater district: U. S. Geol.-and Geog. Survey Terr. Eleventh Ann. Kept., pp. 3-157,1879.

43768° Bull. 641 17 17
250 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PAET II.

The sedimentary formations from the Cambrian up to but not 

including the Wind River (see stratigraphic section on PL XXIII) 

probably once extended in great level beds across the area now occupied by the Granite Mountains and the Sweetwater Valley, as identical 

formations occur on both sides of the anticline, but with and after 

the upheaval that produced the anticline these beds were gradually 

eroded and for the most part if not entirely removed by streams from 

the crown of the anticline. The pre-Cambrian granite has been carved 

at least 2,000 feet deep, as the Granite Mountains rise that much 

above Sweetwater River, and this amount of dissection added to the 

total thickness of the sedimentary strata removed and the present 

altitude above sea level indicates an upward movement of at least 

20,000 feet.

As the oil-bearing formations were removed during the upheaval 

of the anticline and before the deposition of the flat-lying light-colored 

rocks, there was and is now no opportunity for oil to migrate from 

them into the flat-lying rocks, as it is thought to have migrated at 

Douglas, 1 where oil and gas are found in flat-lying beds of the same 

age. Oil and gas, so far as known, have not been obtained commercially in granite. Because of these conditions the middle of the 

Sweetwater anticline offers no possibilities of oil and gas:

SHEEP MOUNTAIN ANTICLINE.

The Sheep Mountain anticline, which is crossed by Beaver Creek, 

lies in the vicinity of Hailey, a roadhouse station some 30 miles 

southeast of Lander. This open faulted anticline is short, lying 

mostly between the Big Bend of Twin Creek and Beaver Hill, a distance of 13 miles, and is almost as wide as long," but in no respect can it 

be called a dome. The rock strata on the northeast limb dip from 

10° to 90°, with an average of about 15°, and those on the southwest 

limb 20° to 30°, as shown in figure 17. The outcrop of the inclined 

beds on the northeast side is much broader than that of the beds on 

the southwest, because of the lower dips and the presence of younger 

rocks that are not represented on the southwest side. Though the 

axis trends in general about N. 30° W., it is curved, with the convex 

side toward the southwest, as is shown by the strike of the formations 

involved in the fold. As the axis of the Sheep Mountain anticline 

passes slightly east of the axis of the Little Popo Agie anticline in 

T. 31 N., R. 98 W., but dies out near the Big Bend of Twin Creek, in 

the southeast corner of T. 32 N., R. 98 »W., the anticline may be 

considered the generalized southward extension of the folds in the 

Lander oil field.2 The axis is inclined and pitches northward, and

i Barnett, V. H., The Douglas oil and gas field, Converse County, Wyo.: U. S. Geol. Survey Bull. 541, 

pp. 49-88,1914.

»Woodruff, E. G., The Lander oil field, Fremont County, Wyo.: U. S. Geol. Survey Bull. 452, pp. 22-27, 

1911.
ANTICLINES IN CENTRAL WYOMING. 251

as the limbs of the anticline which open toward the granite on the 

Beaver divide are eroded the outcrops of none of the 

formations encircle it. Thrust faults at the south end 

of the anticline and near Sheep Mountain have disturbed the normal sequence of the rocks, as shown in 

figure 17. Flat-lying variegated rocks to the east and 

north and light-colored v rocks to the east and south 

closely limit the visible parts of the anticline, which is 

separated from the folds of the Wind River Mountains 

by a narrow downwarp or syncline. Though the Sheep 

Mountain anticline is only from 9 to 18 miles southeast of the Little Popo Agie district of the Lander oil 

field, it probably does not contain important oil pools, 

because it is truncated down to the granite, all the oilbearing formations being exposed. These conditions, g 

in the absence of structural terraces or minor anti- | 

clines about the main upwarp to trap the oil in wet t 

rocks, would allow any oil that was ever present in ^ 

them to escape. No oil seeps were observed on the | 

anticline. |

BIG SAND DRAW ANTICLINE. |

. w

An apparently small anticline 12 miles northeast of ^ 

Hailey is crossed by Big Sand Draw, a tributary of £ 

Beaver Creek, but no permanent water occurs near J 

by. The folded rocks, which outcrop in a strip of |f 

land 6 miles long by 1 to 2 miles wide in Tps. 32 and | 

33 N., R. 95 W., are surrounded by flat-lying younger p 

varicolored strata. The rock strata, as shown in fig- I 

ure 18, dip about 30° on each side of the axis, which |' 

trends a little west of north. The anticline as ex- ^ 

pressed by the sandstone north of Big Sand Draw is ? 

apparent, but to the south it is indistinct in the soft 

folded shale that is partly covered with grass. It 

seems from the small part of the anticline exposed 

that its axis pitches to the north and that none of the 

formations involved in the fold at present encircle 

the anticline.

So far as can be determined from the outcrops, the 

highest oil-bearing formation of Colorado age in this 

anticline is within reach of the drill, though at least 

2,500 feet in depth. Whether or not oil pools are 

present in the anticline is, however, uncertain. Opportunity occurred before the deposition of the flat- | o | 

lying beds for the oil, if then present, to migrate to °- °- °- 

the surface and escape. Likewise, since the deposition of the flat-lying

I L
252 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART II.

beds oil may have migrated upward and accumulated 

in inclined beds abutting against the overlying horizontal beds or in the base of the horizontal beds. This 

could have taken place only in the area south of the 

exposed part of the anticline. If it is assumed that 

the axis pitches in both directions and that the dark 

adobe shale exposed south of Big Sand Draw occupies 

the middle of the anticline, thereby tightly closing over 

the oil-bearing sandstone below, this anticline would 

be perhaps the most promising in the entire field, as oil 

pools might be present in the sandstone thus protected.

ALKALI BTTTTE ANTICLINE.

A northward-pitching, closely folded anticline north 

of the Sweetwater escarpment in the vicinity of Alkali 

Butte and Mount Rogers forms a part of the complex 

folds of the so-called Riverton oil field and is reached 

with least difficulty by a trip of about 15 miles southeast from Riverton, a station on the Chicago & Northwestern Railway. The area about Mount Rogers was 

described by Aughey 1 as the Beaver oil basin. The 

oil, according to him, is of high grade, of 0.968 specific 

gravity, and of a mahogany color. Mount Rogers is 

sometimes spoken of as being on Oil Mountain Ridge, 

but that name leads to confusion with Oil Mountain, 

in the eastern part of the field, so the name Mount 

Rogers is preferable.

That part of the northwestward-trending anticline 

which can be seen is narrow and about 15 miles long. 

Its visible part south of Mount Rogers is shown by the 

closely folded shale and sandstone that pass beneath 

the flat-lying light-colored strata forming the Sweetwater escarpment. These sandstones, tilted at angles 

from 30° to 90°, form sharp ridges about 2 miles long 

in a lowland of shale. (See fig. 18.) The sandstones 

dip rather abruptly in the northwest corner of T. 33 N., 

R. 94 W., at an oil seep, and to the north the arch is 

low but is continued in shale to the vicinity of Alkali 

Butte, where less closely folded overlying sandstones 

form the north end of the anticline. The folded strata 

disappear beneath the nearly level varicolored beds 3 

miles north of the butte, some distance north of the position shown by Woodruff and Winchester.2 In passing

1 Aughey, Samuel, Wyoming Territorial Geologist Ann. Kept., 1886, pp. 124-129.

2 Woodruff, E. G., and Winchester, D. E., Coal fields of the Wind River region, Fremont and Natrona 

counties, Wyo.: U. S. Geol. Survey Bull. 471, pis. 49,53,1912.
ANTICLINES IN CENTRAL WYOMING. 253

along the crest or crown of the anticline it will be seen that the fold 

is sinuous but that both ends trend almost due north. The bend in 

the middle offsets the two straight ends about 2 miles, though there is 

no large fault. The axis rises to the south, as is shown by the absence 

of any visible southward-dipping strata. Erosion has left the anticline incomplete in the sense that it is not encircled by the formations 

involved in the fold. The anticline was developed on the north 

slope of the giant Sweetwater anticline and so is called a slope 

anticline.

In the northwest corner of T. 33 N., R. 94 W. (undivided township), small oil seeps occur in Frontier sands north of Mount Rogers 

and just south of the place where they dip below the shale. From 

one of the seeps a little west of the axis a film of oil accumulates on 

a pool of stagnant water. On the axis oil escapes from the next 

lower sandstone and remains in little depressions or on warm days 

trickles down the slope of the sandstone. Some black residue indicates 

the drying of the oil as it escapes. The largest seeps are about half 

a mile to the south of the seeps above described and north of Mount 

Rogers, a high, flat-topped hill, on the axis of the anticline, where 

oil oozes from a still lower sandstone (Peay) and accumulates in cow 

tracks and other small depressions. Pieces of old rusty machinery 

lying about are signs of a former intention to prospect, possibly that 

of the Omaha Oil & Transportation Co., mentioned by Aughey. 

The record of the well in the position of the unsurveyed SW. | sec. 29, 

T. 33 N., R. 94 W., on Con ant Creek, was not obtained, but seemingly it was a dry hole.

A temporarily abandoned well of the Western States Oil Co., 

begun in the summer of 1913, is 2 miles southeast of the oil seeps, in 

the syncline between the Alkali Butte and the Conant Creek anticlines. It is reported that at a depth of 1,300 feet a showing of oil 

was found in sandstone which is certainly the same as that at the oil 

seeps in the sharp ridge at Mount Rogers.

The Ohio well, drilled in the fall of 1913 a short distance west of 

the axis of the anticline, in the NE. £ sec. 2, T. 33 N., R. 94 W., was 

a dry hole, drilled in dark shale to a depth of 2,930 feet. At a depth 

of 177 feet, in a thin, soft sandstone, a little gas and oil were struck. 

No sand was encountered below 1,070 feet, and no water at any depth.

The Alkali Butte anticline is not regarded as a favorable structure 

for the accumulation of oil and gas, because the upper oil-bearing 

sandstones have been eroded from its crown and because the axis 

rises to the south, so that there is no domed area in which the lower 

oil-bearing sandstones and conglomerates are closed tightly below 

shale. In such an anticline, where the sandstones are saturated with
254 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART II.

water, any oil or gas once contained in them has presumably had an 

opportunity to escape. The oil seeps described above indicate that 

this process is still in operation. There is, however, a chance that an 

oil pool may be found even in spite of these unfavorable conditions.

CONANT CHEEK ANTICLINE.

Southwest of Delfelder's ranch, on the heads of Long and Conant 

creeks, is an open complex anticline crossed by the Sweetwater 

escarpment. Small springs of good water are present along its east 

side and south end, and large sulphur springs issue in the southeast 

corner of T. 33 N., R. 94 W., from beds near its axis. The visible 

part of the anticline covers less than two townships and is limited on 

the north and east by flat-lying variegated beds and on the south by 

nearly level light-colored strata. In plan the Conant Creek anticline 

is short, owing in part to overlapping horizontal beds but more to 

the character of the fold; its axis is sinuous and pitches only in 

one direction. It has, as shown in figure 18 (p. 252), a wide northeast limb and a narrow west limb. Its complexity is due to three 

minor folds on the main anticline and to faults. One of the minor 

folds, which has dips of 18° to 29° and pitches away from the main 

anticline, is on the east side in the northwest corner of T. 32 N., R. 

93 W.; another occurs at Sulphur Springs, and still another to the 

south, which is crossed near the middle by the Sweetwater escarpment. The last two, whose axes are slightly offset, are separated by 

a branch of Conant Creek and really make a large part of the main 

anticline. The dips on the east flank of the south fold range from 

12° to 85° and those on the west flank from 8° to 20°. Small faults 

occur at the north end of the south fold, and a large strike fault 

on the west limb of the northernmost fold possibly furnishes opportunity for the escape of the water at Sulphur Springs. The offsetting 

of the formations in the north-central part of T. 32 N., R. 93 W.. 

is more probably due to a fault than to an acute fold, though this 

is not evident from the manner of grouping formations on the 

map (PI. XXIII).

In the general syncline between the Conant Creek and Alkali Butte 

anticlines there is a small, slightly arched anticline that pitches northward like those on each side. This fold, the Big Sand Draw and 

Alkali Butte anticlines, and the minor folds of the Conant Creek 

anticline resemble in shape and position the fingers of a hand.

A cross section through the anticline near Sulphur Springs (see 

fig. 18) displays dips of 32° to 65° on the narrow west limb, which is 

less than a mile wide, and dips of 30° to 47° in the same strata on the 

northeast limb. The outcrop of these beds on the west limb is about 

2^ miles wide, but that on the east limb is about 8 miles wide, the
ANTICLINES IN CENTRAL WYOMING. 255

greater width being due in part to low dips, but more to the presence 

of a great thickness of beds that are not found on the west limb or 

in the syncline between the Alkali Butte and Conant Creek anticlinesViewed lengthwise the anticline shows a great thickness of beds dipping northward but no corresponding beds dipping southward. The 

absence of southward dips indicates the deep erosion which the anticline has suffered, also that-it is a slope anticline. The anticline 

seems to end about 3 miles north of Sulphur Springs, as the massive 

sandstones along the north side of T. 33 N., R. 94 W., are not noticeably affected by the fold.

The Conant Creek anticline is not a favorable fold for the accumulation of oil and gas, because all the oil-bearing formations are stripped 

from its crest and even though minor folds are present they involve 

mostly the older formations, which generally are not oil bearing. Thus 

in no part of the anticline are the Cretaceous oil-bearing sandstones 

tightly sealed beneath shale in such a manner as to lead to the retention of oil and gas in the presence of water.

BUCK SPRINGS ANTICLINE.

An anticline is indicated by a small area of tilted sandstone beds 

surrounded by flat-lying variegated strata at Buck Springs, in T. 34 

N., Rs. 92 and 93 W., 4 miles east of Delfelder's ranch. In plan the

Buck Springs anticline

FIGURE 19. Section through the Buck Springs anticline, Wyo.

visible part of the anticline is arrow-shaped, pointing northwest, and 

the corresponding beds on both sides dip away from the axis about 

12° or less, as indicated in figure 19. Viewed lengthwise the anticline 

shows only northwestward-dipping beds, and this fact, considered 

with near-by exposures of the same beds that are involved in the 

arch, indicates an inclined axis or a slope anticline.

The relation of the Buck Springs anticline to other anticlines in its 

vicinity is purely speculative, because of the surrounding flat-lying 

beds. However, it is reasonably certain that there is a fault trending 

northeast from a point near the sharp bend of Long Creek possibly 

to the southwest corner of T. 34 N., R. 92 W. No definite fault plane 

is visible, its presence being inferred by the offset in position of the 

outcrop of some of the older formations in the Conant Creek anticline. 

The map, on which the many formations involved in the folds are 

combined into only three groups, does not adequately indicate the 

amount of the offset.
256 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART II.

The Buck Springs anticline is not attractive as oil territory, because 

the oil-bearing Frontier formation is beyond easy reach of the 

drill, lying at a depth of more than 4,000 feet, and because of the pitch 

of the axis as outlined above.

BUTTON ANTICLINE.

An open northward-pitching slope anticline is situated in what is 

known as Dutton Basin, north of the Sweetwater escarpment, 6 miles 

west of the north end of the Rattlesnake Mountains and from 12 to 

25 miles south of Moneta, a station on the Chicago & Northwestern 

Railway. This locality has been referred to in short notes by Aughey1 

and Ricketts 2 as the Dutton oil basin, and later described by Knight 3 

and by Woodruff and Winchester 4 as the termination of an anticlinal 

fold. The part of the anticline not covered by flat-lying variegated 

beds is short and about one-third as wide as long. The southern part 

is marked by northward-converging sandstone ridges, so that in plan 

the formations or contour lines drawn on a particular bed resemble 

a series of nesting V's opening to the southeast. None of the beds 

involved in the fold at present entirely encircle the anticline, and 

viewed from the side it shows a series of northwestward-dipping beds 

and an inclined axis.

The west limb is narrow, with the beds dipping 20° to 45°; on the 

broad east limb the same beds dip 12° to 33°. (See fig. 20.) The

Dutton anticline

FIGURE 20. Section through the Dutton anticline, Wyo.

higher and younger beds involved in the fold on the east limb are not 

repeated on the west limb, being absent because of the oblique angle 

which the axis makes with that of the giant Sweetwater anticline 

and because they have been eroded away. Erosion has stripped all 

the possible oil-bearing formations from the crest or crown of the 

anticline, and it is probable that truncation cut down even to the 

granite prior to the deposition of the flat-lying beds.

The formations on the west limb of the anticline probably join 

with the same formations exposed near the head of Muskrat Creek 

and farther west with those on Conant Creek, as indicated on the 

map (PI. XXIII) by the dashed line under the stippled pattern. The 

northward-dipping beds in Tps. 32 and 33 N., R. 91 W., on Muskrat

1 Aughey, Samuel, Wyoming Territorial Geologist Ann. Kept., 1886, p. 129. 

a Eicketts, L. D., Wyoming Territorial Geologist Ann. Kept., 1888, p. 35. 

3 Knight, W. C., Wyoming Univ. School of Mines, Petroleum ser., Bull. 4, pp. 14-19,1901. 

< Woodruff, E. G., and Winchester, D. E., Coal fields of the Wind River region, Fremont and Natrona 

Counties, Wyo.: U. S. Geol. Survey Bull. 471, p. 551, pi. 49,1912.
ANTICLINES IN CENTRAL WYOMING. 257

 5"cr^l 3

Creek, are a part of the north limb of the giant Sweetwater anticline. 

Likewise, those on the east limb of the Dutton anticline probably join the same formations at the north 

end of the Rattlesnake Mountains. The Dutton 

anticline is separated from the Rattlesnake anticline by a shallow syncline occupied by Deer Creek 

and extending south past Black Mountain to the 

head of Dry Creek. (See fig. 21.)

The Dutton anticline is commonly spoken of as 

the Dutton Basin oil field, but like the " Riverton oil 

field" it does not deserve the name. Oil seeps are 

rare and there are (June, 1916) no producing oil 

wells. The small outcrop of Tensleep sandstone in 

sec. 13, T. 33 N., R. 90 W., is saturated with oil, but 

the seeps mentioned by Knight 1 as occurring in the 

Dakota sandstone, "Niobrara sandstone" [probably 

Frontier], and Tertiary beds were not found. Near 

the apex of the converging sandstone ridges there 

are some bog holes from which a small quantity of 

bad water issues, but no oil was seen. About small 

vents in these places an occasional gas bubble escapes/and there is a distinct odor of hydrogen sulphide. The field has been prospected recently by 

numerous assessment wells and in the early days by 

pits. A well drilled on the axis, about a mile north 

of the apex of the united hogback ridges of the two 

flanks of the fold, obtained a showing of oil and gas. 

The casing was still in the hole at the time of the 

writer's examination, and water stood only a few 

feet below its top. A small amount of gas was being given off, and a sample of heavy dark-brown 

oil was obtained from the top of the water. The oil 

probably came from the Wall Creek sand, as the 

well is reported to have been drilled to a depth of 

about 1,060 feet. It was not analyzed.

Because any oil or gas which may have been contained in the formations has had ample chance to 

escape from then* truncated edges during the erosion 

periods preceding and following the deposition of 

the flat-lying beds, and also because of the meager 

showing of oil seeps, it seems improbable that any 

considerable amount of oil has been conserved in 

this much eroded anticline. Small quantities may 

be entrapped where the oil-bearing formations abut

W O> ^i CD

"o "b b b b

o o o o o

o o o o o

i Knight, W. C., op. cit., pp. 14-18.
258 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART II.

against the flat-lying beds, but even this possibility seems remote.

RATTLESNAKE ANTICLINE (?).

The fold of the isolated Rattlesnake Mountains 

is about 50 miles west of Casper and 15 miles 

southwest of Waltman. The northwest end is anticlinal and faulted, as shown in figure 21, whereas 

from Wallace Creek southeast to Horse Creek the 

strata dip for the most part in one direction (northeast) and are disturbed by large intrusive masses, 

as shown in figure 22. The range has a length of 

about 25 miles, trends about N. 45° W., and parallels most of the anticlines in the area. Viewed 

broadly, it is a deeply eroded anticline resting on 

the granitic rocks of the Sweetwater Valley and 

formed on the northern limb of the giant Sweetwater anticline. Knight 1 considered the range as 

due to a great overthrust fault and shows the fold 

as a large monocline that is, a fold in which the 

strata all dip one way and Trumbull,2 apparently following Knight, also considered it a monocline, but a map by Darton 3 shows a vestige of 

a southwest limb at the north end. Along the 

northeast side of the mountains are the Bighorn, Rattlesnake, and Arago oil basins of some 

writers.

In plan the visible part of the fold is about onethird as wide as long and is encroached upon on 

all sides by the overlapping horizontal white and 

variegated beds deposited during and after the 

principal period of deformation. These level beds 

conceal the true relation of the Alcova and Dutton anticlines to the folds in the Rattlesnake 

Mountains. The outcrops of the formations involved in the folds of the Rattlesnake Mountains 

occur, in plan, in parallel bands with a southwestward-bending hook at the north end. At both 

ends they pass under younger flat beds. The normal dip and strike of the strata have been disturbed by late intrusive rocks, as shown in figure 22.

§000 1 Knight, W. C., op. cit., p. 21.

K <0 m" ^r~ a Trumhull, L. W., Prospective oil fields: Wyoming Geol. Survey Bull. 5, 

pp. 9-10,1913; Light-oil fields of Wyoming: Wyoming Geol. Survey Bull. 12, p. 125,1916.

a Darton, N. H., Paleozoic and Mesozoic of central Wyoming: Geol. Soc. America Bull., vol. 19, pi. 22, 

1908.
ANTICLINES IN CENTRAL WYOMING. 259

This probably explains a small shallow syncline between Arthur Peak 

and Devils Saddle, in T. 32 N., Rs. 86 and 87 W. Large masses of 

intrusive porphyritic andesite form Gaffield Peak, Arthur Peak, 

Devils Saddle, and Goat Mountain. The large white mineral in the 

porphyry is oligoclase-albite and the large black ones alkali pyroxenes. 

Smaller masses of the same rock are found also at many other places, 

shown on Plate XXIII. The sedimentary rocks surrounding these 

igneous rocks usually dip away from the intruded mass, but not uncommonly they are overturned and dip toward it.

A transverse section through the range south of the J E ranch and 

from Black Mountain to Wallace Creek (fig. 21) shows only a few beds 

dipping at low angles into the Deer Creek syncline, but east of the 

granite core these beds, as well as those which are shown by cross 

hatching on the map, dip about 45° E., and many others, mostly those 

not indicated by a pattern on the map, dip east at angles of 25° or 

more for a distance of over 6 miles. North of this section the beds on 

the west limb of the fold dip 37° or more, and in sees. 14, 24, and 25, 

T. 34 N., R. 89 W., a minor short syncline is developed on the main 

fold, as is shown on the map by the indentation of the cross-hatched 

area. A similar section through Arthur Peak (fig. 22) shows only 

eastward-dipping strata, tilted at angles of 16° to 40°, which gradually flatten and pass under the nearly level variegated beds and into 

the F L syncline on the east. The higher dips in general occur along 

the hogbacks forming the foothills of the mountains (the outer part 

of the area indicated by cross-hatching on the map).

The range viewed lengthwise along the summit displays from the 

southeast for 15 miles a granite and schist base, partly veneered with 

flat strata, which are here and there distorted by late intrusions. The 

folded sedimentary formations at the northwest end of the mountains 

dip on an average about 24° N. for a distance of 8 miles and then pass 

beneath the horizontal variegated beds.

It is possible that near the head of Horse Creek there is along the 

southwest side of the mountains a northwestward-trending fault. A 

large fault here, which was assumed by Knight 1 to connect with the 

alleged large fault at Alcova, is highly problematic, but credence is 

lent to this assumption by the fact that a large warm spring in sec. 35, 

T. 32 N., R. 86 W., issues from the supposed fault plane. Probably 

there is no fault of great magnitude at this place, for there is no marked 

offset of the formations near Deer Creek, in T. 34 N., R. 89 W., and 

the south end of the supposed fault near Alcova is not evident. There 

is, however, in T. 33 N., R. 88 W., at the north end of the Rattlesnake 

Mountains, a fault a few miles in length, but no further positive evidence was seen of such a large fault as would be necessary to account

"Knight, W. C., op. cit.,p. 21. v
260 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART II.

for the absence in the Sweetwater Valley, southwest of the Rattlesnake Mountains, of the older as well as the younger folded formations that are present on the northeast side of the mountains. The 

formations probably once extended across Sweetwater Valley and have 

been eroded, because all of them having similar characteristics are 

found at Whiskey Peak and Green Mountain in Tps. 27 and 28 N., 

Us. 89 and 90 W.

The indications of oil found at many places in the Rattlesnake 

Mountains are confined chiefly to the conglomerate (see section on 

PL XXIII) in the lower part of the Cretaceous and to the Dakota. 

These have been described by Aughey, Ricketts, Knight, and Trumbull in the papers already 'cited. At the Lew Smith spring, in sec. 

26, T. 32 N., R. 86 W., a very small quantity of dark asphaltum 

issues from the bottom of a ravine in the flat-lying beds. It originates ' 

in either the conglomerate or the sandstone (Dakota), which are 

only a few feet below the surface. Southwest of Oil City, where the 

same conglomerate is more extensively saturated, a dark asphaltum 

oozes from its outcrop. A small outcrop of a higher sandstone 

(Frontier) in this vicinity, in the SE. J SE. \ sec. 8,"T. 32 N., R. 86 W., 

shows traces of oil. Between this locality and Garfield Peak no oil 

was found, but north of the peak, on Wallace Creek and on small 

draws cutting the upturned rocks in the hogback ridges from sec. 

28, T. 33 N., R. 87 W., to sec. 34, T. 34 N., R. 88 W., the same conglomerate and sandstones as are found farther south are saturated 

with oil, and from seeps along the creek valleys dark asphaltum 

accumulates to considerable depth over many square rods. In this 

district there are traces of oil in all the formations from the Chugwater to the Dakota, also in the Frontier, and even the Teapot 

sandstone at Phayles Reef, in sees. 4, 5, and 9, T. 33 N., R. 87 W., 

is saturated with oil. The indications of oil are less and less pronounced toward the north end of the mountains, where there are no 

showings whatever.

The exact location of the two wells of the Central Association of 

Wyoming, drilled 700 and 900 feet deep, which passed through the 

"Fox Hills" [Frontier] and obtained some light oil, and of the one 

sunk by the Northwestern Oil Co. in September, 1887, which also 

obtained some light oil and water at 480 feet in the "Fox Hills" 

[Frontier], is not recorded 1 unless, as seems probable, they are the 

ones shown by Knight in sec. 34 and in sec. 28 or 29, T. 34 N., 

R. 88 W.

Two other shallow wells have been drilled along the mountains, 

one 1,130 feet deep at Oil City, which struck only a slight showing of 

oil at a depth of 500 feet, and one near the west quarter corner of 

sec. 20, T. 33 N., R. 87 W., which obtained a showing of oil and gas.

i Aughey, Samuel, op. cit., p. 134. Ricketts, L. W., op. cit., p. 35. Knight, W. C., op. cit., p. 28,map.
ANTICLINES IN CENTRAL WYOMING. 261

During the summer of 1913 some prospecting was done with Star 

rigs along the east side of the mountains, but no oil was obtained.

The Rattlesnake anticline is not considered favorable for the conservation of oil and gas, because none of the oil-bearing formations 

are closed tightly below thick shale beds in anticlinal folds. The 

fact that oil escapes from the outcrops of the formations along the 

east flank of the mountains seems to signify that most of the oil has 

been forced by water pressure to the outcropping edges of the formations, so that little remains in them at present, and wells drilled 

down the dip from the outcrop may be expected to strike plenty of 

water. It is not considered that the outcrops of these more or less 

saturated sandstones and conglomerate are so clogged with oxidized 

oil and asphalt as to make them reservoirs for oil down the dip, as 

occurs in some of the California fields. 1 This unfavorable view of 

the significance of such seeps is supported by the fact that the beds 

dip rather uniformly along the whole front of the mountains except 

in the area affected by the Wallace Creek dome (?), so that no structural ten-aces or minor anticlines occur.

WALLACE CHEEK DOME(?).

A fold somewhat resembling a dome occurs in T. 34 N., R. 87 W., 

far out on the northeastward-sloping beds involved in the upturned 

limb of the Rattlesnake anticline or along the west limb of the F L 

syncline, according to the viewpoint of the individual. The syncline 

has been referred to as the Powder River syncline.2 Wallace Creek, 

a tributary of Powder River, has eroded the flat-lying variegated 

beds from most of the township and displayed older folded rocks, 

which show dips of 3° to 10° or in some places 17°. In a section 

taken in a N. 45° E. direction across the northwestern part of the 

township there are strata dipping southwest as well as northeast, 

but in one taken in a similar direction through the dome and along 

the creek only eastward-dipping beds occur. A low arch is present in 

a section taken in a northwesterly direction. The folding seemingly 

did not progress sufficiently to form a complete dome, as there are no 

southwest dips along the south side of T. 34 N., R. 87 W.

The Wallace Creek dome (?) is less attractive than some other areas 

as a possible oil reservoir, because the proved oil-bearing formations 

are too deep to be reached easily by the drill. The highest sandstone 

showing oil in the region is the one saturated with oil at Phayles 

Reef, in sees. 4, 5, and 9, T. 33 N., R. 87 W. It is at least 4,000

1 Arnold, Ralph, and Anderson, Robert, Geology and oil resources of the Coalinga district, Cal.: U. S. 

Geol. Survey Bull. 398, pp. 187-189,1910.

2 Woodruff, E. G., and Winchester, D. E., Coal fields of the Wind River region, Fremont and Natrona 

counties, Wyo.: U. S. Geol. Survey Bull. 471, p. 553, pis. 49,56,1912.
262 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PAET II.

feet and perhaps much more below the surface. Before the Wallace Creek dome (?) is finally condemned as oil territory, a well should 

be drilled deep enough to test this sandstone. If a test well is to 

be drilled, preparations should be made to go 6,000 feet or more if 

necessary.1

The Franco-American well, in sec. 16, T. 34 N., R. 87 W., though 

not completed when the area was examined, struck no oil. The 

well was sunk more than 2,000 feet and may have reached well into 

the Lance formation.

It is interesting to note that the largest showings of oil in the upturned beds along the Rattlesnake Mountains are almost directly 

opposite the dome on Wallace Creek and that the heavily saturated 

Phayles Reef lies in the intervening area, but it is impossible to say 

whether or not this intervening area contains a body of oil.

ALCOVA ANTICLINE.

The town of Alcova is about 30 miles up North Platte River from 

Casper, in the midst of an area of folded rocks that have been exposed by the erosion of the river. The fold at Alcova may be considered as the southward-pitching end of an anticline that is paralleled 

on the east by the F L syncline and on the west by a narrow syncline 

and farther west by a monocline resting on the granitic nucleus of the 

giant Sweetwater anticline. The Alcova anticline is believed to be 

a part of the limb of the large Sweetwater fold.

The geology at Alcova has been briefly described by Knight,2 who 

shows the tilted beds as a faulted monocline.1 In a later paper 3 he 

refers to the fault as the Fremont thrust fault. The stratigraphy of 

this locality has been described briefly by Darton,4 who shows the 

folds as a faulted anticline and monocline.

The visible part of the unsymmetrical anticline is about 16 miles 

long by about 7 miles wide, and it trends about N. 60° W. In passing along the south eastward-pitching axis from the northwest corner 

of T. 30 N., R. 83 W., through the Hot Springs gorge to the vicinity 

of the southeast corner of T. 30 N., R. 82 W., successively higher or 

younger rocks are encountered. The strata on the broad northeast 

limb dip on an average 10°, whereas those on the narrow southwest 

limb dip as much as 60°, as shown in figure 23.

The formations involved in the fold at first sight seem to be repeated by faulting, because the broad band of red rocks (Chugwater 

formation) on which Alcova is located is apparently repeated farther

' Trumbull, L. W., Prospective oil field at Upton, Buck Creek, Rattlesnake Mountains, and Labarge: 

Wyoming Geol. Survey Bull. 5, p. 10,1913.

2 Knight, W. C., Artesian basins of Wyoming: Wyoming Univ. Bull. 45, p. 236,1900.

3 Knight, W. C., Wyoming Univ. School of Mines, Petroleum ser., Bull. 4, p. 21,1901. 

< Darton, N. H., Paleozoic and Mesozoic of central Wyoming: Geol. Soc. America Bull., vol. 19, pp. 

405-488, pi. 21,1908.
ANTICLINES IN CENTRAL WYOMING. 263

up the North Platte by the alleged Fremont thrust fault, as shown 

by Knight and Darton, but on closer inspection it ^ w o> 

is found that the formations from the Chugwater 900 

up to the Niobrara may be traced continuously 

from the east limb of the anticline around the point 

of the fold and along the west limb, except where 

they are covered by flat-lying beds, as just west of 

the river, and connected with the same formations 

in the monocline below the Pathfinder dam. The 

traces of these formation boundaries are of the form 

of very much depressed Z's. The formations have 

been somewhat compressed on the west limb of the 

Alcova anticline, for even though the beds are on 

edge west of Hot Springs and along the Devils 

Gardens, there is scarcely sufficient width of outcrop to accommodate the normal thickness of the 

formations. It is possible that there are some small 

strike faults along the crushed zone that represent 

the southeastward dying out of the large fault on 

the southwest side of the Rattlesnake Mountains 

assumed by Knight. A small normal fault trending 

southwest about 4 miles northwest of Alcova and 

3 miles east of the Childress ranch, offsets the formations about 200 feet.

The exact relation of the folds at Alcova to those 

in the Rattlesnake Mountains, on the northwest, or 

those in the Freezeout Hills, on the south, is obscured by the unconformable flat-lying beds. The 

strike of the beds in the Rattlesnake Mountains is 

in harmony with the strike of the beds at Alcova, 

and as the formations are the same in each area, 

they probably join beneath the flat-lying beds. The 

broken line beneath the stippled pattern on the 

map indicates such a connection. The intervening 

distance is about 12 miles, and it is assumed that 

truncated edges of the formations from Cambrian 

to Fort Union abut against the flat-lying beds. It 

is possible that where the formations that show 

large seeps of oil along the front of the Rattlesnake 

Mountains abut against the level beds these overlying beds may act as a trap, and oil pools may have 

formed either in the sands below or in the level beds 

themselves, but it is believed that no large pools 

may be expected here.

The area immediately about .Alcova apparently

has no future as oil territory, because the anticline is eroded below
264 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART II.

all the oil-bearing formations, allowing easy escape of oil and gas 

from the outcrop and leaving no favorable places for pools to be 

formed. No oil seeps were seen about Alcova, and the well drilled 

several years ago in sec. 25, T. 30 N., R. 83 W., 2 miles above the 

village, was a dry hole. Its location is in the syncline between 

the Alcova anticline and the monocline to the west and is in as unfavorable a site for a test well as could have been selected.

BATES HOLE ANTICLINE.

The anticline in Tps. 30 and 31 N., R. 81 W., in the middle of the 

Bates Hole country, is a small upwarp trending approximately N. 

45° W. It lies a short distance northeast of the folded rocks at 

Alcova, south of the Goose Egg anticline, and immediately west of 

the highly folded and faulted rocks of the Laramie Mountains. It 

is in line with the axis of the F L syncline, which lies west of the 

Pine dome and Oil Mountain anticline. The axis of the Bates Hole 

anticline pitches at both ends at low angles and has a sag a short 

distance north of the south township line of T. 31 N., R. 81 W., 

making two unequal parts, of which the larger is the broad southern 

portion of the anticline, in the northeast corner of T. 30 N., R. 81 W., 

and the smaller the narrow northern portion of the anticline, in the 

southwest corner of T. 31 N., R. 81 W. A small strike fault, not 

shown on Plate XXIII, occurs south of the middle of the anticline. 

The anticline has a narrow west limb in which the beds dip from 70° 

to 90° and a broad east limb in which the same beds dip less than 40°.

West of the small north end of the Bates Hole anticline and separated from it by a narrow syncline is a small dome or short simple 

anticline covering less than a square mile. The dips in the encircling sandstone ridges that indicate its presence are about 50° on 

all sides.

In this small dome and also in the north end of the main anticline 

the Dakota sandstone is from 500 to 800 feet below the surface. 

The Tensleep sandstone is less than 1,500 feet below the surface in 

the middle of the southern part of the anticline. Because of the 

presence of this and other sands which yield oil or show indications 

of it in other localities, there is a possibility that the Bates Hole 

anticline may contain oil or gas. No indications of oil, however, 

were found on it at the surface.

GOOSE EGG ANTICLINE.

The faulted anticlinal fold of the Casper Range, a part of the giant 

fold of the Laramie Mountains, enters the southeast corner of this 

field in T. 32 N., R. 81 W., and structurally terminates in the anticline forming Goose Egg Mountain, a small outlier separated from
ANTICLINES IN CENTRAL WYOMING. 265

the main range by North Platte River.1 The mountain rises about 

1,000 feet above the river.

The Goose Egg anticline as expressed in plan consists of a series 

of nesting V-shaped lines representing structure contours or even 

contacts of formations that open toward the Laramie Mountains 

and point westward. Its axis, sloping down from the giant anticline of the Laramie Mountains, pitches at a fairly high angle and 

trends a little south of west, at a considerable angle to the axes of the 

surrounding anticlines. (See £1. XXIII.) The Casper fault,2 which 

brings the granite to the surface in the Laramie Mountains, and the 

Emigrant Gap anticline limit the Goose Egg anticline on the northeast. As viewed in a north-south cross section near the highest 

part of the mountain the strata on the south flank of the anticline 

dip from 16° or possibly less to 21°, as shown in figure 24, but north 

of the axis in a narrow crushed zone they dip at very much higher 

angles and are even overturned. North of the highly tilted beds 

the dips decrease rapidly and the strata flatten, forming the large

Goose Egg anticline

FIGURE 24. Section through the Goose Egg anticline, Wyo.

bulge or arc on the north side of the anticline, as indicated in Plate 

XXIII.

The Goose Egg anticline is not considered favorable for the accumulation of oil and gas, because all the oil-bearing formations are 

exposed at the surface except the Tensleep sandstone, which is only 

a few feet below the river. This probably is water-logged even on 

the crown of the anticline, for a large spring that is used to irrigate 

about 1,000 acres of Bessemer Flats issues from the base of the 

Chugwater formation in the crest of the anticline.

IRON CREEK ANTICLINE.

The Iron Creek anticline occupies a small area in the northwest 

corner of T. 32 N., R. 82 W., where its crest is shown by inclined 

sandstone beds that form encircling ridges about an inner shale 

basin, and each sandstone is in turn surrounded by a shale valley.3

1 Hayden, F. V., U. S. Geol. Survey Terr. Fourth Ann. Kept., pp. 26-28,1872.

2 Hayden, F. V., idem. Darton, N. H., Paleozoic and Mesozoic of central Wyoming: Geol. Soc. 

America Bull., vol. 19, pi. 21,1908; Preliminary report on the geology and underground water resources 

of the central Great Plains: U. S. Geol. Survey Prof. Paper 32, pp. 53-55,1905. Barnett, V. H., Possibilities of oil in the Big Muddy dome, Converse and Natrona counties, Wyo.: U. S. Geol. Survey Bull. 

581, pp. 105-117, 1915. Spencer, A. C., The Atlantic gold district and North Laramie Mountains, Wyo.: 

U. S. Geol. Survey Bull. 626, pi. 4,1916.

8 Hayden, F. V., op. cit., p. 28.

43768° Bull. 641 17 18
266 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART II.

It is the fold connecting the Oil Mountain and Goose Egg anticlines. 

Like the Oil Mountain anticline, it trends northwest, but it is nearly 

at right angles with the Goose Egg anticline. The strata on the 

north end of the Iron Creek anticline dip 42°; those on the south end 

only 11°. The strata on the east side dip from 20° to 60° and the 

same beds on the west side from 31° to 62°, as shown in figure 25.

Iron Creek anticline

5,000'

Ks -4,000'

FIGURE 25. Section through the Iron Creek anticline, Wyo.

The fold is ideal for the accumulation of oil and gas in wet rocks, 

but only the drill will show whether or not oil, gas, or water occurs in 

the Cretaceous sands below the Frontier sandstones, or in the conglomerate, sealed below impervious shale.

OIL MOUNTAIN ANTICLINE.

The Oil Mountain anticline, in Tps. 32 and 33 N., R. 82 W., a little 

over 15 miles west of Casper, is a small unsymmetrical fold, whose 

middle portion is indicated by concentric shale valleys and sandstone 

and conglomerate ridges that rise considerably above the surrounding 

country. The lower and outer portions of the flanks of the anticline, 

formed of soft shale, are less conspicuous than the inner portion, where 

the sandstones are exposed. The strata of the west limb dip rather uniformly at angles of 29° to 46° close to the mountain, but farther west 

the dips are as great as 80°; those on the east limb dip only 7° out on 

the flanks, but are vertical or even overturned close to the axis. The 

axis pitches abruptly southward and gently northward. (See fig. 26.) 

A strike fault with a throw of over 1,000 feet repeats the outcrop 

of some of the formations northwest of Oil Mountain, and the oil 

spring in sec. 28, T. 33 N., R. 82 W., is on the fault plane. East 

of the fault the rocks dip at low angles (3° to 9°) and show a marked 

flattening of the anticline in sees. 15, 16, 17,19, 20, and 21, T. 33 N., 

R. 82 W., as indicated in figure 27. This flattening lies mostly south 

of Poison Spider Creek and presumably is the "peculiar U-shaped 

fault "of Knight. 1

At the oil spring in sec. 28 heavy dark oil accumulates on water in 

an old prospect pit. The ground about the spring is slightly saturated and pieces of asphaltum lie on the surface. The oil possibly 

comes from the Lower Cretaceous conglomerate, which is only a few 

feet below the surface on the west side of the fault plane.

The Tensleep sandstone lies about 1,500 feet below the surface on 

the crest of the Oil Mountain anticline, and the Lower Cretaceous

i Knight, W. C., Wyoming Univ. School of Mines, Petroleum ser., Bull. 4, pp. 33-35,1901.

268 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART II.

conglomerate is only a short distance below the surface just west of 

the fault plane in sec. 28. These two localities, which are the most 

favorable for the retention of oil because of their position in the anticline and because some of the oil-bearing sands are sealed in the beds 

underlying them, should be tested before the Oil Mountain anticline 

is condemned as nonoil land.

MINOR ANTICLINES BETWEEN POISON SPIDER CREEK AND THE 

SOUTH FORK OF CASPER CREEK.

Between Poison Spider Creek and the south fork of Casper Creek 

there are three minor anticlines on the general anticline which extends from the Pine dome to Oil Mountain. These folds when compared with the Pine dome and the Oil Mountain anticline are small 

in area as well as in degree of deformation and topographic effect. 

They are separated from one another by transverse sags developed 

on the main anticline, as shown in figure 26. The northernmost of 

the three minor anticlines is about 4 miles long, and the same strata 

on both sides of it dip about equally at angles ranging from 15° to 30°. 

The middle one is about 3 miles long; the strata on the west side dip 

from 7° to 60°, but those on the east side only from 3° to 24°. The 

southernmost of the three is very small, being less than a mile long. 

The strata on the east side dip from 6° to 49° and those on the west 

10°. The dip of 49° on the east side is exceptionally steep.

These minor anticlines doubtless have afforded opportunities for 

the accumulation of oil and gas, but whether they still contain oil 

and gas can not be determined with certainty prior to actual drilling. 

The two wells already drilled are near the axis of the general fold 

extending from the Pine dome to the Oil Mountain anticline, but in 

the cross sag between the Oil Mountain anticline and the minor anticlines. One, of these, the Guthery well, 960 feet deep, in the SE. J 

SE..J sec. 18, T. 33 N., R. 82 W., is reported to have obtained a showing of oil. The Ohio well, in the NW. \ SE. J sec. 18, T. 33 N., 

R. 82 W., obtained showings of oil in the Dakota sandstone, the 

Lower Cretaceous conglomerate, and the Morrison formation, but 

found the Tensleep sandstone, at a depth of 2,715 feet, water-logged. 

These sands, which are all sealed below impervious shales in the 

crowns of the anticlines, should be properly tested by the drill before 

the anticlines are finally condemned as of no value for oil. The dry 

holes do not necessarily prove that the anticlines do not contain oil, 

for many dry holes are drilled in and about any proved oil field.

PINE DOME.

The Pine dome, a large faulted dome forming Pine Mountain, 25 

miles northwest of Casper, lies just south of the railroads and covers 

most of Tps. 34 and 35 N., Rs. 83 and 84 W. The dome is moderately
ANTICLINES IN CENTRAL WYOMING. 269

arched and shows fairly steep dips about the sides, but in a large 

area on the crest or top the strata lie almost flat. (See figs. 27 and 

28.) The dome is limited on the east by the syncline between it 

and the Emigrant Gap anticline. On the northwest a wide cross 

sag south of Powder River station separates it from the Cottonwood 

Creek anticline, and a cross sag at South Casper Creek limits it on the 

south side from the minor anticlines north of Poison Spider Creek. 

The flat-lying variegated beds reach up on its west side.

This moderately arched dome forms the north end of a compound anticline that extends from Pine Mountain to Oil Mountain, 

trends N. 45° W., and parallels the Rattlesnake and Emigrant Gap 

anticlines. The general fold on which the Pine dome and Oil Mountain anticline are developed is one of the connecting folds between the 

giant anticlines of the Laramie and Bighorn Mountains, the other 

connecting fold being the Emigrant Gap anticline. The distance 

between the most northerly beds of the Pine dome and the most 

southerly beds of the Cottonwood Creek anticline, a fold situated 

upon the south limb of the Bighorn Mountain uplift, is but 3 miles. 

The relations of the dome to the Laramie uplift on the south are 

even closer.

The dips on the north, east, and south sides of the dome are low, 

ranging from 6° to 24.°, but those on the southwest, west, and northwest are from 11° to 90° and some of the strata on the west side 

are even overturned as much as 22°. Because of these high dips 

the resistant sandstone and hard shale beds form about the dome 

encircling hogback ridges that are in places impassable, and the beds 

of soft shale between the sandstone give rise to narrow valleys that 

with the sandstone ridges are continuous around the dome except 

where all are faulted out on the west side, as shown in figure 28, 

or are cut by small dry canyons heading in the mountain. An 

overthrust fault on the west side has a throw of about 2,000 feet, 

and a similar fault on the northwest side has a throw of about 800 feet.

No oil seeps were seen in the Pine dome, though it is reported that 

oil has been gathered from a tunnel in sec. 27, T. 35 N., R. 84 W. 

When this tunnel was visited some dirty black water was flowing 

from it, but no traces of oil were seen. The Pine Dome Oil Co. is reported to have brought in during the summer of 1914 a 2,000,000- 

foot gas well on the east side of the mountain in sec. 36, T. 35 N., 

R. 84 W., close to the crest of the dome, and just below the gas water 

was obtained, presumably in the Tensleep sandstone, which is entirely 

sealed in this dome. The Cretaceous sandstones are all eroded from 

the crest, and consequently if oil in commercial quantities exists here 

it must be sought in older rocks, such as the Carboniferous. This 

question can be determined only by drilling.
270 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART II. 

ANTICLINE SOUTHWEST OF POWDER RIVER STATION.

About 2£ miles southwest of Powder River station is a small open 

anticline involving at the surface the coal-bearing rocks that form 

prominent curved ridges of sandstone. Like other anticlines in this 

area it trends northwest.. The axis presumably pitches at low angles 

at both ends, even though no formation completely encircles the 

anticline. The arch is limited on the east by a shallow syncline l 

that occurs between it and the Pine dome. The beds on the southwest side of the anticline dip from 25° to 72°, but the same beds on 

the east side dip 32° or less.

The Wall Creek sand, which is the principal oil-bearing sand at 

Salt Creek, is at least 3,000 feet and perhaps more than 4,000 

feet below the surface on the crest of the arch. Because of the 

great depth of this sandstone, if for no other reason, the fold is not 

an attractive place to prospect for oil, although the facts that the 

Cretaceous oil-bearing sands are not exposed and that the anticline 

has a fairly large gathering ground in the great F L syncline suggest 

the possibility that it may contain oil.

COTTONWOOD CREEK ANTICLINE.

The compound anticline crossed by Cottonwood Creek, in Tps. 

36, 37, and 38 N.; Rs. 84, 85, and 86 W., is a minor upwarp on the 

south end of the great uplift of the Bighorn Mountains. It may be 

considered as a small southward-pitching anticline branching off 

from the margin of the greater anticline. The Cottonwood Creek 

anticline is in line with and probably was developed at the same time 

as the Pine dome and Oil Mountain anticline, which form a part of 

the fold that unites the Laramie and Bighorn uplifts. It is separated 

into two parts by a low cross sag which is followed by the perennial 

Cottonwood Creek in its eastward course just below the Desert 

ranch. To the north the limbs of the anticline gradually diverge 

and pass into the northward-rising beds of the Bighorn anticline. 

The axis of the northern part of the Cottonwood Creek anticline 

rises and is lost on the south end of the giant anticline of the Bighorn 

Mountains near the north side of T. 38 N., R. 86 W. The crown of 

the southern part of the anticline, in sees. 3 and 10, T. 37 N., R. 85 

W., is shown by the tilted sandstone beds forming escarpments that 

dip away from this area. The part of the anticline south of Cottonwood Creek is short, as the area of sandstones hi the middle is only 

about twice as long as wide, but, as shown in figure 29, the slightly 

dipping west limb continues across the flats to a point within a short 

distance of the railroad, where the dips increase rapidly, giving in

i Woodruff, E. G., and Winchester, D. E., Coal fields of the Wind River regioa, Fremont and Natrona 

Counties, Wyo.: U. S. Geol. Survey Bull. 471, p. 557, pi. 56,1912.
ANTICLINES IN CENTRAL WYOMING. 271

effect a broad, low arch. Its axis trends in general northwest, but 

just west of Powder River, in the southwest corner 

of T. 37 N., R. 84 W., its direction is assumed with 

question to be east of north. The river crosses the 

extreme south end of the fold.

The strata on the east side of the Cottonwood 

Creek anticline dip 25° to 30°, much more steeply 

than those near the crown on the west side (6° to 

10°), but not so steeply as those on the extreme 

west side (60° or more). In this respect the anticline is like those on the south and west sides of 

the field.

The Toltec well, in sec. 11, T. 37 N., R. 85 W., 

near the crown of the anticline, struck much warm 

sulphur water under considerable pressure at a | 

depth of 915 feet, in the conglomerate which is § 

shown on the stratigraphic section on Plate XXIII. 8 

The Cottonwood Creek anticline is likely to be bar- g> 

ren of oil and gas because the upper oil-bearing 5- 

sandstones are exposed at the surface, allowing | 

opportunity for the oil to escape, and the lower § 

sandstones and conglomerate are water laden. j*

BIG SULPHUR SPRINGS ANTICLINE.

The Big Sulphur Springs anticline, in Tps. 37 and 

38 N., Rs. 83 and 84 W., is crossed by South Fork | 

of Powder River and is one of the minor folds | 

branching off from the Bighorn anticline. A cross | 

sag followed by the river separates the anticline -* 

into two parts, one south of the river and the "g 

other on the slope of the Bighorn Mountains. The 

axis of the anticline is sinuous but in general 

trends northwest. South of Big Sulphur Springs 

the dips on the east flank are about 30° and those 

on the west flank about 5° ; south of the river those 

on the east limb are about 10° or less and those 

on the west from 1° to 4°, as shown in figure 30. 

This anticline differs from many of the other anticlines in this region in having low dips on the 

west limb and steep dips on the east. South 

of the river a small fault at right angles to the 

axis has a throw of some 300 feet, and the beds 

on the north side have moved up relative to 

those on the south side. The folding here is similar to that in the

( 0 f,

§ § 8 § 8 o o o o o
272 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART II.

Cottonwood Creek anticline in trend and in that a small anticline 

is separated by a cross sag from the main uplift of the Bighorn 

fountains.

Big Sulphur Springs anticline 

Kf

FIGURE 30. Section through the Big Sulphur Springs anticline, Wyo.

The Big Sulphur Springs anticline is not considered favorable for 

the accumulation of oil and gas, because the conditions are similar to 

those in the Cottonwood Creek anticline, where the sandstones even 

near its crown contain water under pressure.

EMIGRANT GAP ANTICLINE.

The Emigrant Gap anticline is just west of Casper and trends 

about N. 45° W. from the Casper fault,1 at the north side of the 

Laramie Mountains, to the Chicago & Northwestern Railway, a distance of about 20 miles. It is parallel to and about 10 miles east of 

the general anticline on which the Pine dome and Oil Mountain anticline are developed and with those uplifts forms a uniting fold between the giant anticlines of the Bighorn and Laramie mountains.2 

The anticline is much broader at the south end than it is at the 

north, as is indicated by the tapering outcrop of the formations involved in the sharp fold. (See PI. XXIII.) Between this and the 

Big Sulphur Springs anticline there is a cross synclinal area which is 

the eastward continuation of the one at Powder River station, between the Pine dome and the Cottonwood Creek anticline. The 

axis of the Emigrant Gap fold is nearly in line with that of the Big 

Sulphur Springs anticline.

The dips of the beds on the narrow west limb of the Emigrant 

Gap anticline range from 40° to 70° and those on the east side near 

the axis from 8° to 30°, but farther east terrace-like structure is 

shown by the semicircular outcrop of the sandstones and shales in 

the southern part of the anticline (see PL XXIII), where the dips 

are as low as 1° to 7°, as shown in figure 31. The anticline is crossed 

near the middle by a cross sag that divides it into two parts. The 

southern part is the more pronounced because it is folded more, is 

eroded deeper, and is marked by prominent sandstone ridges, but it 

is the less attractive economically because nearly all the oil-bearing 

formations in it are exposed. The northern part has neither been 

folded so much nor eroded so deeply as the southern part and offers

i Hayden, F. V., U. S. Geol. Survey Terr. Fourth Ann. Kept., pp. 26-28, 1872. 

»Idem, p. 28.
ANTICLINES IN CENTRAL WYOMING. 273

more inducement to prospecting, for some of the oil-be'aring formations in it are sealed below shale. (See figs. 31 and 32.)

North of the cross sag which divides the anticline into two parts 

there are two minor upfolds on the main fold. They are indicated 

in the field by inclined beds of Frontier sandstone that form 

encircling ridges and escarpments. The southern one is domeshaped and lies in sees. 19, 20, 29, and 30, T. 34 N., R. 81 W. The 

dips on the west side are about 70°, but those on the other sides are 

only 6° to 9°, as indicated in figure 32. On the crest of the dome 

the beds of sandstone are flat. A' slight cross trough on the main

FIGURE 31. Section through the south end of the Emigrant Gap anticline, Wyo.

anticline, on which is located the United States Geological Survey 

primary-control station in the SE. \ SE. J sec. 24, T. 34 N., R. 82 W., 

separates the dome from the northern one of the two minor upfolds. 

This cross trough, instead, of being a topographic depression like 

most of such features, is an eminence rising 5,955 feet above sea 

level.

The northern one of the minor upfolds, an ideal fold for the 

accumulation of oil and gas in wet rocks, is in sees. 15, 22, 23, 24, 25, 

and 26, T. 34 N., R. 82 W. The dips on the southwest side average 

about 70°; those on the northeast are about 8°. Because of this

Emigrant Gap anticline

rVI

FIGURE 32. Section near the middle of the Emigrant Gap anticline, Wyo.

great difference in the tilting of the beds the sandstones on the 

northeast side form a prominent, impassable southwestward-facing 

escarpment, but in contrast the same rocks on the southwest form 

only low hogback ridges. The crown of the anticline, in the SW. £ 

sec. 23, is shown by the outcrop of a hard shale, forming a slight hill 

in a large shale basin. This minor upfold is separated from the north 

end of the main fold-by a slight cross trough near the corner of sees. 

9,. 10; 15, and 16, where the sandstones close over the principal arch. 

The crown of. the north end of the main anticline is mostly confined to 

sees. 4 and 9, T. 34 N., R. 82 W., and sec. 33, T. 35 N., R. 82 W. The
274 CONTEIBUTIONS TO ECONOMIC GEOLOGY, 1916, PAET II.

dips on the west side of the north end of the Emigrant Gap anticline 

range from 30° to 50°, and those on the east side are-20° or less.

The Emigrant Gap anticline shows no oil seeps and has not been 

prospected except by two wells far down on its east limb, on Casper 

Creek, and by a shallow well in the SE. \ sec. 9, T. 33 N., R. 81 

W., drilled in the summer of 1914 by the Monongahela Oil Co. 

The well last mentioned, which is near the axis of the anticline and 

near the cross sag that divides the fold into two parts, obtained a 

flow of strong sulphur water at a depth of 240 feet. The anticline 

merits consideration as a favorable fold for the accumulation of oil 

and should be prospected farther south, hi the south-central part of 

of sec. 25, T. 33 N., R. 81 W., to test the Tensleep sandstone, which 

is about 1,000 feet below the surface; also farther north in sees. 9 and 

23, T. 34 N., R. 82 W., and in the northeast corner of sec. 30, T. 34 N., 

R. 81 W., to test the Mowry shale, the Dakota sandstone, the Lower 

Cretaceous conglomerate, and possibly the Morrison formation, 

which are from 500 feet or less to 1,000 feet below the surface. The 

first wells should be drilled near the center of sec. 23, T. 34 N., R. 82 

W., and if the formations named are found to be water-logged there 

it would probably be of little use to drill in the other localities in the 

northern part of the anticline.

NORTH CASPER CREEK ANTICLINE.

The North Casper Creek anticline, a simple fold in Tps. 36 and 37 

N., Rs. 81 and 82 W., is about 22 miles northwest of Casper, between

N.Casper Creek anticline r K^ 

_____-4-.000' 

FIGURE 33. Section through the North Casper Creek anticline, Wyo.

the old Hemmingway and Roseberry ranches. It is sometimes 

referred to as the Hemmingway dome. The anticline lies northeast 

of the Emigrant Gap anticline, and its trend'is parallel to that of the 

other anticlines in this general region. Unlike most of these folds, it 

produces little effect on the topography because of the~slight magnitude of the "fold and because erosion has barely exposed one of the 

oil-bearing sands (the Wall Creek) on the very crown of the arch in 

the midst of Cretaceous shale.

In plan the formations crop out in elliptical bands about the anticline, the crest of which lies near the southeast corner of sec. 1, T. 36 N., 

R. 82 W.; where the Wall Creek sand is exposed. -As shown in figure 33, 

in transverse section the strata on the west side dip at angles of 8° or 

less, but east of the axis the dips are somewhat higher and in one 

place reach 45°. In a lengthwise section the axis is gently arched 

and pitches both northward and southward at angles of about 6°.
ANTICLINES IN CENTRAL WYOMING. 275

The steep dips on the east side are in harmony with similar dips on 

the east side of the Big Sulphur Springs and Castle Creek anticlines, 

but in contrast to the dips on the east side of the other anticlines hi 

this area and those in the near-by Powder River l and Salt Creek 2 

anticlines.

There are no oil seeps in the North Casper Creek anticline, and the 

three wells drilled about it struck considerable water in all the 

sandstones they encountered. However, an area about 4£ miles 

long by 1^ miles wide, or about two-thirds as large as the proved 

Salt Creek field, yet remains on the crown of the anticline, and it 

must be drilled before the presence or absence of oil can be fully 

determined. All the sands that show indications of oil ha this field 

or adjacent fields, except the Teapot and the Wall Creek, are beneath 

the surface in this anticline. One or two deep wells drilled in sec. 1, 

T. 36 N., R. 82 W., would perhaps show whether this anticline contains oil, which the three wells drilled to the northwest of its crest 

have not conclusively done. These wells have shown that the sands 

in the lower parts of the anticlines are full of water, but other test 

wells higher up on the arch might strike oil or gas or both.

CASTLE CHEEK ANTICLINE.

The Castle Creek anticline, an open fold in Tps. 37 and 38 N., Rs. 

80 and 81 W., near the head of Castle Creek, is indicated on the 

ground by a westward-facing escarpment of Shannon sandstone, 

trending northwest across the west side of T. 38 N., R. 80 W., and a 

low northward-facing rim of the same sandstone on the north side 

of T. 37 N., Rs. 80 and 81 W. South of the 33 Mile ranch, in sec. 5, 

T. 37 N., R. 81 W., the escarpment fades away, owing to the greater 

softness of the sandstone and perhaps to its thinning. The axis of the 

fold, which trends northwest, may possibly represent the southward 

extension of the axis of the Powder River anticline,1 and if so considered the axis as a whole is sinuous, like that of the Big Sulphur 

Springs anticline, with a sharp bend along the east side of T. 39 N., 

R. 81 W., to conform to the outcrop of the sandstones.

The strata on the east limb of the Castle Creek fold dip about 15°, 

and those on the southwest limb about 7°, as shown in figure 34. So 

far as observed there are no northward or northwestward dipping 

rocks in the Castle Creek fold, and thus the axis pitches gently southeast. For this reason none of the formations encircle the fold, and 

in this sense the anticline is at present incomplete.

The drill hole of the Midwest Oil Co., near the east quarter corner 

of sec. 31, T. 38 N., R. 80 W., is in a well-chosen locality near the

i Wegemann, C. H., The Powder River oil field, Wyo.: U. S. Geol. Survey Bull. 471, pp. 56-75,1912. 

»Wegemann, C. H., The Salt Creek oil field, Natrona County, Wyo.: U. S. Geol. Survey Bull. 452, pp. 

37-83,1911.
o o o o o

o o o o o

O O O Q, O

m ^ co w -T

276 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART II.

middle of the fold. It was sunk to a depth of about 2,000 feet and 

a little gas was obtained in the shale above the 

Wall Creek sand, but as this was the objective 

sand of the test well and as it was found to contain water drilling was stopped. Two wells have 

been started in sec. 28, T. 38 N., R. 81 W., but the 

first was abandoned before being finished and operations on the other, owned by the Casper Oil Co., 

which started in October, 1914, ceased in January, 

1915, at a depth of 1,900 feet. This well is entirely 

in shale and has struck no oil or gas. No oil seeps 

were seen during the field examination, and none 

are reported as occurring here. The anticline may 

not contain oil or gas in commercial quantities, 

though it is situated only a few miles southwest of 

the Salt Creek oil field, the most productive field 

in Wyoming.

POSSIBILITIES OF OBTAINING OIL.

From the results obtained by the wells already 

drilled in this field, which have cost at a moderate 

estimate over $200,000, it would seem at first thought 

that the country should be condemned as oil territory and that further expenditure of large sums of 

money would be fruitless. But if oil and gas in 

Wyoming have accumulated according to the anticlinal theory, which demands, in water-saturated 

rocks, that they are forced to or toward the crowns 

of the anticlines, and as this theory applies to the 

productive Salt Creek and Bighorn Basin fields, then 

the anticlines in central Wyoming have not been 

thoroughly and properly prospected. Nearly all the 

wells have struck large flows of water in the several 

sands from the Wall Creek down to the Tensleep, 

and as these sands outcrop either in the mountains 

of this area or in those adjacent to it, it is highly 

probable that the sands in all localities, except possibly in the structurally higher parts of some of the 

anticlines, contain water.

The attention of those who may in the futureprospect in this area should be directed toward the 

most promising places in the most favorable anticlines and away from those which on account of 

pitching only in one direction or on account of having been eroded too deeply are not favorable for the 

accumulation of oil or gas. There are a few anticlines in the area
ANTICLINES IN CENTRAL WYOMING. 277

in which possible oil-bearing sands are not exposed at the surfaceAs the rocks are charged with water under pressure, these places 

should be tested if further prospecting is attempted. The anticlines in which one or more of the oil-bearing formations the 

Frontier sandstones, Mowry shale, Dakota sandstone, Lower Cretaceous conglomerate, Morrison and Embar formations, and Tensleep sandstone lie within reach of the drill beneath thick shale 

beds are the North Casper Creek, Iron Creek, Emigrant Gap, and 

Oil Mountain anticlines, the minor anticlines north of Poison 

Spider Creek, and the anticline southwest of Powder River station. The most promising of these are the Emigrant Gap anticline (northern part), the minor anticlines between Poison Spider 

Creek and Casper Creek, the North Casper Creek anticline, and possibly the anticline southwest of Powder River station; and should 

these prove after thorough prospecting to be barren of oil, then the 

chances are against finding oil in the other anticlines of the area. 

The proximity of the North Casper Creek anticline to the proved 

Salt Creek dome suggests the possibility of there being an oil pool at 

this locality. The first two wells drilled in the summer of 1913 did 

not test the North Casper Creek anticline sufficiently to prove its 

character. As has already been pointed out, the wells are not located 

on the crown of the anticline, and two of them were drilled either only 

into the Wall Creek sand, which is exposed on the crown of the anticline, or only through the Frontier formation. There are no oil 

seeps from this sandstone where it is exposed on the crown of the 

anticline, and the negative 'results of drilling, taken in conjunction 

with the absence of oil seeps, prove conclusively that this sand, which 

is the chief oil-bearing sand of the Salt Creek field, 1 does not carry 

oil in the North Casper Creek anticline. The well drilled in the fall 

of 1915 by Mr. Fitzhugh and associates was farther up on the anticline and was sunk as deep as the Lower Cretaceous conglomerate 

and obtained water; therefore it has, with the other two wells, 

proved that a large part of the North Casper Creek anticline is barren 

of oil, and there remains only a few square miles of the highest part 

of the crown yet unprospected. Oil in this anticline may possibly 

be found in some lower sand, such as those in the lower part of the 

Frontier, the Lower Cretaceous conglomerate, or the Morrison formation, which lie 100 to 1,500 feet below the Wall Creek, or possibly 

the Tensleep, which is about 3,400 feet below the Wall Creek, or in 

some of the numerous intermediate sands. One or two wells drilled 

near the southeast corner of sec. 1, T. 36 N., R. 82 W., to a depth of

' Wegemann, C. H., The Salt Creek oil field, Natrona County, Wyo.: U. S. Geol. Survey Bull. 452, pp. 

37-83,1911.
278 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1916, PART II.

about 3,500 feet, would possibly demonstrate whether this anticline 

contains oil.

Some of the same formations as those noted above are sealed below 

thick shale beds in the minor anticlines on the northern part of the 

Emigrant Gap anticline. The Mowry shale is the lowest formation 

exposed in them, and it is possible that the underlying sands, at 

depths less than 2,500 feet, may be oil bearing, especially as this part 

of the Emigrant Gap anticline is one of the nearest anticlines in the 

entire area to the great Powder River basin and hence has a large 

gathering ground for the accumulation of oil and gas. However, 

whether or not it contains oil can not be foretold prior to a test by the 

drill. Test wells should be located in sees. 9 and 23, T. 34 N., R. 82 

W., and the first one should be drilled in sec. 23, which is the most 

promising part of the anticline.

Conditions similar to those in the northern part of the Emigrant 

Gap anticline exist in the minor anticlines north of Poison Spider Creek, 

and these anticlines should be tested near the SE. £ NE. | sec. 3 and 

the center of sec. 12, T. 33 N., R. 83 W., and possibly near the east 

quarter corner of sec. 18, T. 33 N., R. 82 W.

The formations from the Frontier to the Tensleep are below "the 

surface of the Iron Creek anticline, and it is possible that the Mowry 

shale or some of the underlying sandstones pr the conglomerate might 

contain oil or gas. A test well on Iron Creek within the inner sandstone rim would probably determine, if drilled to a depth of approximately 3,000 feet, whether or not oil is to be obtamed in this anticline. 

The Mowry shale is about 500 feet below the surface, and the Lower 

Cretaceous conglomerate and Morrison formation would be reached 

at a depth of about 1,500 feet.

Likewise, the crest of the Oil Mountain anticline itself should be 

tested. Perhaps in this fold oil may be found in some sand like the 

Tensleep. A 1,500-foot well, properly located, would test the Tensleep sandstone in this anticline.

Attention should be paid also to the area southwest of the fault 

northwest of Oil Mountain, for this area is opposite the oil seep at 

the fault, and there is west of the fault an area of arched beds involving at the surface rocks as low - as the Dakota. A well about 1,800 

feet deep would possibly demonstrate whether or not the Lower Cretaceous conglomerate, the Morrison formation, and the Tensleep sandstone will yield oil in this place.

The Wall Creek sand is from 3,000 to 4,000 feet below the crest of 

the small anticline southwest of Powder River station, otherwise this 

fold might be considered favorably as a place to sink a test well.

Conditions similar to those in the Oil Mountain anticline exist in the 

south half of the Emigrant Gap anticline, where the Sundance formation occupies the crown of the anticline and the Tensleep sandstone
<J. 8. QEOLOGICAL SURVEY BULLETN 641 PLATE XXIII

TERTIARY

TERTIARY?

GENERALIZED SECTION 

FOR CENTRAL WYOMING

White River formation 

O-I.5OO'

Tertiary intrusive

Wind River formation 

0-2,900'

Unconformity

e * o n

.%!;* &

CRETACEOUS

u fct t-OWCi «^j

JURASSIC 

TR'IASSIC'J

CARBONIFEROUS-^

PRE1-CAMBRIAN

Tfu

K<riv

Ks

Kshn>

Ks

w.

Kmy

Ksh

aWgf

Fort Union formation

35Or -2,<»28'

Lance formation 

25O'-2,7I5'

Coal

Lewis formation 

lOO'-l,QOOr

YTeapot ss member 50r-20.o' 

>Mesaverde formation 8OO'-|,2OOr 

JParkman ss member 35O.'

>Steele shaU

hannoo ss lentil 0-80*

Niobrara shale

4OO'-l,75Or

^Carlile shale I50*'230'

r

ail Creek-ss member 

rrontier formation 

soo'-i.ooo'

Mowry shale 25Or-30Or f 

Thermopolis shale iso'-jqp 

Dakota sandstone O-60 

Shale 100' 35Or , 

Conglomerate 8-60 T Morrison formation 250 

Sundance formation 300'

Chu^water formation 

900' -1,200'

Embar formation. 225 

Tensleep sandstone 200-^00' 

Amsden formation 35Or* 

Madison-limestone 1OO-TOO 

Unconformity 

Limestone, shale, and quartzite A-00-637

Schist l,000 f i 

Granite

Hat-tying White River

and Wind River forma- V

tion

formations from top 

of Port Union to base 

of Niobrara

Formations from top 

of Carlile to base of 

Cambrian

Location of cross sections shown in text

R. 94 W. .93,

* Gas welt

* Show of oil

* Show of gas

* Show of oil and gas

Synclinal axis

Strike and dip fr Dry hole p Spring

R. 97 W

95 94 93 92 91 9O 89 87

MAP SHOWING ANTICLINES IN NATRONA AND FREMONT COUNTIES IN CENTRAL WYOMING.
ANTICLINES IN CENTRAL WYOMING. 279

is about 1,000 feet below the level of North Platte River. The Bates 

Hole anticline falls in the same class.

The Pine dome has been shown by the well of the Pine Dome Oil 

Co. to contain gas, and as the Tensleep sandstone is wholly sealed 

here, the dome looks hopeful.

The large quantities of asphaltum on Wallace Creek and its tributaries along the east front of the Rattlesnake Mountains naturally 

suggest that there is an oil pool somewhere to supply the asphaltum, 

unless, as is possibly the case, the rocks are so eroded as to have 

allowed all the oil to escape. It should be noted that these exceptional showings of oil along the mountains are almost directly opposite the Wallace Creek fold and that a line drawn from the middle 

of that fold to the exceptional seeps along the mountain would pass 

close to Phayles Reef, which is highly saturated with oil. These 

seeps may be in some way related to the Wallace Creek fold, where 

perhaps the oil is caught, but in this fold all the formations below the 

Teapot sand of the Mesaverde formation, which outcrops at Phayles 

Reef, are beyond the reach of the drill.

The United States Geological Survey can not state positively that 

oil or gas in commercial quantities exists in any of these anticlines, 

but it does suggest that some of them appear, after field examination, 

to offer favorable conditions for the accumulation of oil and gas. 

Drilling is the only method of ascertaining whether or not oil or gas 

can be found in these folds.