Geology and Mineral 

Fuels of Parts of 

Routt and Moffat 

Counties, Colorado

By N. WOOD BASS, J. BRIAN EBY, and MARIUS R. CAMPBELL

A CONTRIBUTION TO ECONOMIC GEOLOGY

GEOLOGICAL SURVEY BULLETIN 1027-D

A study of coal, oil, and gas in the 

Mount Harris, Pilot Knob, Elkhead 

Creek, and Daton Peak quadrangles

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1955
UNITED STATES DEPARTMENT OF THE INTERIOR

Douglas McKay, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

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

Washington 25, D. C: , 
CONTENTS

Pagt

Abstract.. .. 143

Introduction. __-_-_-_-____.._____-__-.________--__-_---____-_ __._ 144

Location. ____________________________________________________ 144

Accessibility _________________________________________ 144

Settlement. ____ ____.__..._ __ _____ ________ 145

Climate.___________________________________ 146

Drainage. _____________________________________________________ 146

Surface features_________________._.._______________________ 146

Mineral deposits__ ________________ __ 147

Previous geologic work_________________________________________ 148

Field work for this report_____________________________________ 148

Acknowledgments. _____________________________________________ 149

Stratigraphy_______________________________________________________ 150

Cretaceous (Upper Cretaceous) rocks_________________________.__ 150

Mancos shale__.________________________________________ 150

Mesaverde group______________.._________________________ 152

lies formation_____________..___________________________ 154

Williams Fork formation___________________.___________ 157

Lewis shale___________________..______.____________________ 159

Lance formation__________________________________________ 160

Tertiary rocks__ _____________________________________________ 161

Fort Union formation (Paleocene)__ ________________________ 161

Wasatch formation (Eocene). _______________________________ 161

Browns Park formation(?) (Miocene or Pliocene). _-___.___.._ 161

Quarter nary (?) rocks, unconsolidated surficial deposits____________ 162

Igneous rocks _____________________________________________________ 163

General features.. ____________________________________________ 163

Metamorphism.. _ ______________________________________________ 164

Structure...________________.____.__ ___._-. 169

Coal.-_______-_--_--_-_---__-_-__________-____________----_---___ 171

Lower coal group. ____________________________________________ 171

Middle coal group_________________..___________________________ 173

Upper coal group. __________________________________________ 174

Coal beds in the Lance and Fort Union formations._______________ 175

Quality.....______________________________________________ __-_ 175

'Reserves. _-_---_-__-___-__-______..-___-___________-------_-__ 176

Oil and gas.-__--______________________: _______..^_ 178

Literature cited_____________________________________________^____ 181

Index. _______________________________________'_ 249

m
IV CONTENTS

ILLUSTKATIONS

[Plates 18-25 IB pocket]

PLATE 16. Sandstone ledges of the lies formation. A, Ledges in lower 

part of lies formation north of Williams Fork near Pagoda; 

B, ledge of the Trout Creek sandstone member north of 

Hayden Gulch_________________________________ Facing 154

17. A, View of Mount Harris showing the ledge of the Twentymile 

sandstone member of the Williams Fork formation; B, cast 

of a dinosaur footprint in the roof of theWadge coal .mine at 

Mount Harris____________-_______--_____-____.__ Facing 155

18. Generalized columnar section .of exposed rocks in parts of 

Routt and Moffat Counties.

19. Geologic map of parts of Routt and Moffat Counties.

20. Chart showing correlation of coal groups in the Mesaverde 

group and key beds in the Mesaverde group and upper part 

of the Mancos shale.

21. Columnar sections of rocks exposed or penetrated by coredrill holes in the Williams Fork Mountains. 

22-25. Coal sections in parts of Routt and Moffat Counties. 

FIGURE 38. Index map of Colorado showing location of the mapped area__ 145 

39. Generalized columnar section showing zones of metamorphism

of coal above and below a sill in the Cottonwood Creek area. 167

TABLES

TABLE 1. Analyses of coal samples_________________ 184

2. Comparison of averages of analyses of samples of coal from

several stratigraphic positions________________________ 208

3. Measured and indicated, undifTerentiated, original bituminous

coal reserves __ ___ ______ _____________ 209

4. Inferred original bituminous coal reserves._________________ 221

5. Measured and indicated, undifferentiated, original subbituminous coal reserves..................................... 224

6. Inferred original subbituminous coal reserves.______________ 230

7. Original bituminous coal reserves, listed by counties and

townships____________________________________________ 232

8. Original subbituminous coal reserves, listed by counties and

townships.__________________________________________ 234

9. Measured and indicated, undifferentiated, and inferred original

coal reserves, listed by counties and townships ________ 236

10. Analyses of gas samples from the Tow Creek and Williams

Park fields_____________________________ 238

11. Analyses of crude oil from the Tow Creek and Oak Creek

fields._______________________________________________ 339
A CONTRIBUTION TO ECONOMIC GEOLOGY

GEOLOGY AND MINERAL FUELS OF PARTS OF ROUTT 

AND MOFFAT COUNTIES, COLORADO

By N. WOOD BASS, J. BRIAN EBY, and MARIUS R. CAMPBELL

ABSTRACT

The Mount Harris, Pilot Knob, Elkhead Creek, and Daton Peak quadrangles 

comprise an area of about 1,000 square miles in northwestern Colorado. Most of 

the area is in Routt County, and the rest is in Moffat County. The largest river 

is the Yampa, which flows westward across the middle of the area. Much of the 

land has a rolling surface, and some is rugged, particularly that in the north and 

south parts of the area.

The mapped area lies in the southeastern synclinical prong of the Washakie 

structural basin of central Wyoming and northern Colorado. In Colorado the 

syncline is bordered on the east by the Park Range, a large anticline, and on the 

southwest by the Axial Basin anticline. The axis of the syncline extends southeastward across the mapped area, passing near Hayden. The regional synclinal 

structure is modified by many folds, particularly in the eastern and southern parts 

of the mapped area. The largest of these is the Tow Creek anticline. Others are 

the Wolf Creek dome, 3 miles northwest of the Tow Creek anticline; the Chimney 

Creek dome in the northeastern part; the Williams Park and the Beaver Creek 

anticlines and the Pagoda dome, near the southern margin; the Hart syncline in the 

southwestern part; and the Twentymile Basin in the eastern part of the mapped 

area.

A stratigraphic sequence of Upper Cretaceous and Tertiary rocks, which are 

about 13,000 feet thick, is present. The Mancos shale, the oldest formation cropping out in the area, is about 4,900 feet thick; all but the lowermost 300 feet is 

exposed. It consists primarily of homogeneous dark-gray shale, much of which is 

limy. A thick sequence of very limy shale and thin chalky limestone of Niobrara 

age is present in the lower part of the formation, and beds of thin, silty ledgeforming sandstone occur in the upper 1,000 feet. The Mesaverde group, which 

is divided into the lies and Williams Fork formations, is about 3,000 feet thick 

and consists of interbedded ledge-forming sandstone, sandy shale, shale, and coal 

beds. Two thick white sandstone members form conspicuous key beds the 

Trout Creek sandstone near the middle of the group and the Twentymile sandstone 

in the upper part. The Lewis shale, which overlies the Mesaverde group, is a 

marine sequence of dark-gray shale, 1,500 to 1,900 feet thick. The Lance and 

Fort Union formations overlie the Lewis shale. Each is about 1,400 feet thick 

and consists of thick sandstone beds, sandy shale, and some coal beds. The 

Wasatch formation, which overlies the Fort Union formation, is about 1,000 feet 

thick and consists of beds of coarse brown sandstone, or grits, interbedded with 

gray and red clay shale.

Thick flows of basalt interbedded with ash are present on the south margin of 

the area. Dikes, sills, and plugs of igneous rock occur chiefly in the northeastern 

quarter of the area.

143
144 CONTRIBUTIONS TO ECONOMIC GEOLOGY

The strata include many thick beds of bituminous and subbituminous coal. 

Anthracite and semianthracite are present locally in the northeastern part of the 

area where the coal has been metamorphosed by thick sills of basalt. Slightly 

more than 9 billion tons of coal of all ranks is estimated to be present between the 

surfaces and a depth of 3,000 feet. The Mesaverde group contains three principal 

groups of coal beds the lower, middle, and upper. The coal of the lower and 

middle groups is here referred to as bituminous; and that of the upper group is 

referred to as subbituminous, although it is on the margin between bituminous 

and subbituminous ranks. Lenticular beds of subbituminous coal, some of which 

are thick, are present in the Lance and Fort Union formations. The Mesaverde 

coal is mined near Oak Creek, Milner, Mount Harris, and Hayden, which are 

accessible by a railroad and paved roads. Two fairly large strip coal mines are 

operated, one near Oak Creek and the other near Milner. The other mines in 

the area are underground.

Oil is produced at Tow Creek and was produced for a short time at Oak Creek. 

Gas is present at Pagoda, Williams Park, and Chimney Creek. The Pagoda and 

Williams Park fields contain shut-in gas wells. The wells on Chimney Creek 

yielded shows of considerable gas but were not completed for commercial production.

INTRODUCTION

LOCATION

Deposits of coal, oil, and gas are present in the Mount Harris, Pilot 

Knob, Elkhead Creek, and Daton Peak quadrangles in northwestern 

Colorado. Most of this area is in southwestern Routt County, and 

the rest is in southeastern Moffat County (fig. 38). The area is 

known to the coal industry as the eastern part of the Yampa coalfield. 

It comprises about 1,000 square miles, including all or parts of Tps. 3 

to 9 N., Rs. 85 to 90 W.

ACCESSIBILITY

The Denver & Rio Grande Western Railroad (formerly the Denver 

& Salt Lake Railroad) crosses the center of the area from east to "west 

in the Yampa River valley. Its western terminal is Craig, 2% miles

west of the area. The railroad passes producing coal mines at Mount 

Harris, McGregor, and near Oak Creek and Hayden, and passes 

through the Tow Creek oilfield. The oil well near Oak Creek connects 

with it by a short pipeline. 

Gfe U. S, 40, a hard-surfaced road, crosses the area by the same route

as ;tK© railroad. Another hard-surfaced, road from. Oak Creek to

U. S. 40 passes through the coal-mining towns north of Oak Creek.

A gravel-surfaced road in Williams Fork valley connects with u, s, 40

at Hayden by another gravel-surfaced road that passes up Hayden 

Gulch and Dry Creek, where several coal mines are located. Graded

flirt roads, and trucK trails tnat lead t/o sheep and cattle camps, oroaa 

most of the area; the Pagoda gasfield in the south-central part of the 

area is accessible by a truck trail. Most of the rugged country is 

accessible only by horse trails.
GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 145

"KB8 io~* W i55"5 J* jj jr

FIGURE 38. Index map of Colorado showing location of the mapped area. 

SETTLEMENT

Craig, the county seat of Moffat County, is 2K miles west of the 

area. It has a population of more than 3,000 and is the supply center 

for ranchers, coal miners, and for oil exploration in the western part of 

the mapped area and in a large area adjacent to it on the west. Steamboat Springs (population about 2,000), the seat of Koutt County, is 

on the railroad and U. S. 40, nine miles east of the area. It is the 

source of supply for much of the ranching and the coal and oil industry 

of Routt County. Oak Creek (population 1,500), which is in the 

southeastern part of the mapped area, and Mount Harris, which is a 

few miles east of the center, are important coal-mining communities. 

Hayden, at the center of the area, is a source of supply for ranching and 

coal mining in that vicinity. Milner is a small town near the east 

margin of the area, and Phippsburg is at the extreme southeast 

corner. McGregor, wnich is three-fourths of a mile southwest of 

Milner, was at one time the site of several coal mines but now supports 

only one operation, a strip mine; it is also the site of the power plant 

that supplies electricity to towns in Yampa River valley. Bear River, 

about 1 mile northeast of Mount Harris, was formerly a coal-mining 

town. It was abandoned and the buildings were dismantled in 1940, 

following the shutdown of the Bear River coal mine. Coal View, 1% 

miles southeast of Bear River, was abandoned many years ago. 

Habro is a coal-mining town 2% miles north of Oak Creek.
146,' - CONTRIBUTIONS TO ECONOMIC GEOLOGY

Many stock ranches are in the valleys of Yampa River, Williams 

Fork, South Fork, Willow Creek, Oak Creek, Trout Creek, Fortification Creek, and Elkhead Creek, and a few ranches are elsewhere 

in the mapped area.

CLIMATE

The climate of the mapped area is semiarid. The average annual 

precipitation ranges between 15 and 22 inches (Colorado State 

Planning Commission, 1951, map showing distribution of precipitation in Colorado). A broad belt of country that extends from the 

west-central part of the area to the southeast corner receives an 

average annual precipitation of less than 20 inches. The precipitation 

is greatest in the high country in the northeastern part and in the 

extreme southern part. Even in the belt of country having the 

least precipitation there is sufficient moisture for raising crops by 

dry farming. Seasonal precipitation records for Craig, 2K miles west 

of the area, and for Steamboat Springs, 9 miles east of the area, differ 

greatly. At Craig the period of least precipitation is from November 

through February, and at Steamboat Springs it is from June through 

September. The average annual snowfall at Craig and Steamboat 

Springs is 57 and 159 inches, respectively. At Hayden, in the center 

of the mapped area, the average annual precipitation is 16.23 inches, 

which is fairly evenly distributed throughout the year. Of this total, 

1.47 inches falls in April, 1.56 inches in May, 1.18 inches in June, 1.32 

inches in July, 1.42 inches in August, and 1.57 inches in September,

During the summer the days are warm and the nights cool. Winters

are relatively cold. TJtie average dates of the first and last killing'

frosts at Hayden are September 14 and June 10, respectively.

DRAINAGE

The principal river of the area is the Yampa, which flows westward 

across the middle of the area. Williams Fork and its tributaries 

drain the southernmost part, and Oak, Trout, Middle, Foidel, and 

Fish Creeks drain the southeasternmost part. The principal streams 

from east to west in the north half of the area are Wolf, Elkhead, and 

Fortification Creeks.

SURFACE

Tne eastern margin of ite area lies less than 10 milfiS W6St Of the 

Park Range, which reaches altitudes of 12,000 feet above sea level. 

Altitudes within the mapped area range from 10,600 feet on Sand 

Mountain near the northeast corner, to 6,200 feet on Yampa River at 

the west edge. An area characterized by a rugged surface extends 

northward from Yampa River valley across the northeastern part of 

the area and includes Wolf Mountain, Pilot Knob, the Run Rocks, and 

Sand Mountain. A mountainous country in the north-central and
GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 147

northwestern parts includes Quaker Mountain, Agner Mountain, 

Sugarloaf Mountain, Pinnacle Mountain, and Little Buck Mountain. 

The central and west-central parts are characterized by rough rolling 

surfaces; this country lies west and southwest of the Pilot Knob-Wolf 

Mountain ridge and extends from a short distance south of Agner 

Mountain southward to within a few miles of the crest of the Williams 

Fork Mountains. Twentymile Park in the southeastern part of the 

area is gently rolling, and Williams Park in the south-central part is 

roughly rolling. Rugged southwestward-facing cliffs (pi. 16A), 

deeply incised by gulches, extend from points northeast of the Williams 

Fork River in the southwestern part of the area to the southeast 

corner. The western portion of this rugged country is called the 

Williams Fork Mountains.

The northernmost prongs of the Flat Tops reach the south margin 

of the area. Rugged, boulder-capped slopes descend northward from 

these mountains and merge with the roughly rolling country lying 

south of the Williams Fork Mountains.

MIXEEAL DEPOSITS

Many thick beds of bituminous and subbituminous coal are present 

in the Mesaverde group in the eastern and southern parts of the area, 

and many beds of subbituminous coal, some of which are thick, are 

present in the Lance and Fort Union formations in the northwestern 

part. Coal, whose rank varies locally from bituminous to anthracite, 

is present in the Mesaverde group in the northeastern part of the area. 

Mesaverde coal is mined extensively at Oak Creek, Mount Harris, and 

south of Hayden; a few small mines are operated intermittently in 

Lance and Fort Union coal in the northwestern part of the area. 

Routt County, which includes much of the eastern part of the Yampa 

coalfield, ranks third in the production of coal in Colorado. Moreover, 

interest in possible new coal-mining operations in Routt and Moffat 

Counties is currently centered in areas where the coal can be mined by 

stripping.

The Tow Creek oilfield, which was discovered in 1924 and now 

yields about 100 barrels of oil a day, and the abandoned north Tow 

Creek oil pool, are in the east-central part of the area. Oil was discovered in 1949 near Oak Creek, near the southeastern corner of the 

area, and the well is reported to have yielded more than 100 barrels of 

oil a day for a short time. The Pagoda and Williams Park gas pools 

are in the south-central part of the area; both pools are shut-in. Some 

gas was found in wells in the east-central part of the area, but the wells 

were noncommercial. Deeper sands than those already tested are 

prospectively valuable for oil and gas on a few anticlines.
148 . CONTRIBUTIONS. TO'.ECONOMIC GEOLOGY "" ' 

PREVIOUS QEOLOQIC WORK

The general region was traversed and mapped geologically^by 

S. F. Emmons (1877), geologist with the 40th parallel survey in 1872, 

4 years before Colorado was granted statehood. A geologic description, including a map, is given in his report of the region. Four years 

later the region was visited by C. A. White (1878 and 1889), a geologist 

with the Hayden survey. Topographic and geologic maps and 

descriptions, which are contained in reports of that survey, call 

attention to extensive coal deposits.

In the late eighties and early nineties, rumors that a railroad would 

be built into this region stimulated exploration, immigration, and 

settlement. Geologists and mining engineers employed by the proposed Denver, Northwestern & Pacific (later the Moffat) Railroad 

investigated the resources of the area. From 1886 to 1905 several 

articles about the coal in the area were published. These included 

papers by F. F. Chisholm (1887), L. S. Storrs (1902, p. 435-436), G. C. 

Hewett (1889, p. 376), R. C. Hills (1893, p. 354-358), H. F. Parsons 

and C. A. Liddell (1903), and W. Weston (1904?, 1909, and 1914). 

A geologic report describing the coal deposits of the area was published 

by the U. S. Geological Survey in 1906 (Fenneman and Gale, 1906). 

Exploitation of the coal on a relatively large scale followed the arrival 

of the railroad in 1906. The coal in and near Twentymile Park was

described by Campbell (1923).

FIELD WORK FOB THIS REPORT

This report includes the results of fieldwork done by several geologists. M. R. Campbell spent several months between 1918 and 1930 

working in various parts of the mapped area, particularly in the Mount

Harris quadrangle. Only the part of his work that was done early in 

this period has been published (Campbell, 1923). In 1923 and 1924,

J. B. Eby worked in the Elkhead Creek quadrangle, the west half of 

the Pilot Knob quadrangle, and the Williams Fork Mountains. In

1925, 1937, and 1940, N. W. Bass worked in the Pilot Knob and 

Daton Peak quadrangles. In 1909, J. A. Davis and Frank R. Clark 

mapped and measured the coal beds hi the western part of the Williams 

Fork Mountains in the Daton Peak quadrangle. E. T. Hancock,

3D. E. "Winchester, and. J. D. Sears examined, small areas. In 1943r

J. W. Huddle and N. D. Hainan mapped the Williams Park anticline. 

Frank D. Spencer had charge of core drilling in the west-central part

of the Baton Peak quadrangle in 1948 and 1949. Much of the data

on the coal revealed by the core drilling were compiled by Spencer. 

Data included in reports on the Yampa coalfield by Fenneman and 

Gale (1906) and M. R. Campbell (1923) were used in the'preparation. 

of this report.
GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 149

Most of the geologic boundaries and key beds that appear on themaps of this report were drawn in the field on Geological Survey 

topographic maps. Topographic maps were also used to locate outcrops of coal beds and most prospect holes and mines; however, some 

of the prospect holes and mines were located by planetable mapping 

by the topographers at the tune of their fieldwork.

The coal-bearing rocks hi Tps. 4 and 5 N., R. 89 W., and T. 5 N., 

R. 90 W., in the Williams Fork Mountains, were mapped in 1909 by 

the Davis and Clark party, and the coal beds were trenched with pick 

and shovel. Later, land surveys were made by the General Land 

Office, and topographic mapping was done by the Geological Survey. 

In 1923, the Eby party located on the new base maps the outcrops of 

the coal beds greater than 5 feet in thickness that Davis and Clark 

had described. The coal beds were trenched and measured at the 

places shown on the present map. The coal beds of the middle and 

lower coal groups, hi T. 5 N., Rs. 89 and 90 W., were prospected in 1948 

and 1949 by core drilling.

Coal beds in the lower and middle coal groups were identified by 

measuring the intervals between the top of the Trout Creek sandstone 

member of the lies formation and the individual coal beds. The coal 

beds in the upper coal group were identified by measuring the intervals 

between the top of the Twentymile sandstone member of the Williams 

Park formation and the individual coal beds. However, correlation 

of the coal beds by this method, particularly of the beds that are 

separated by only thin intervals, is tentative. Errors are expected 

because the tops of the members probably are not at the same horizons 

throughout the area, and because the intervals between them and the 

coal beds are not constant. Therefore, little confidence can be placed 

in the identification of coal in this area, except in a few places where 

a sequence of several coal beds is exposed.

The geologic map of the area is shown on the topographic base, 

which was mapped hi 1915, 1916, 1923, and 1924. The positions of 

several roads and small mining communities have been changed since 

the maps were issued.

ACKNOWLEDGMENTS

Officials of several coal companies, including the Moffat Coal Co., 

Colorado and Utah Coal Co., Victor-American Fuel Co., McNeil Coal 

Co., Curtis Coal Co., Bear River Coal Co., and Habro Coal Co., furnished core-drill records, mine maps, and other data and courtesies 

that are gratefully acknowledged. Many individual coal operators 

and other persons provided information about mines and prospects, 

particularly H. I. Hoklas, George T. Rolfs, J. B. Burns, H...C. Mar-, 

chant, A. E. Falney, Gower Reese, H. C. Johnson, Ramsey Harris, 

Jack Mills, Frank Coryell, Earl Rice, R. W. Hendricks, S, B. Pruitt,
150 . CONTRIBUTIONS TO ECONOMIC GEOLOGY

Alexander Walker, W. C. Hammond, T. P. Greenhalgh, and the late 

Kasper Webersckirch.

The Texas Co., through H. A. Stewart and H. E. Christensen, 

furnished much geologic information about the Tow Creek anticline 

and oilfield, and the Williams Park anticline and gasfield. The 

General Petroleum Corp., through J. E. Keenan, furnished geologic 

data about the Pagoda gasfield.

M. R. Campbell was assisted in the field by A. A. Baker, K. K. 

Landes, and N. W. Bass; J. B. Eby was assisted by N. C. Beck and 

W. H. Newhouse; N. W. Bass was assisted by K. H. Eddy of Hayden, 

Colorado. J. W. Huddle and N. D. Raman mapped several square 

miles in the south-central part of the area, including the Williams 

Park anticline. Mining engineers J. J. Bourquin, K. V. Cammack, 

and C. M. McConnell supplied many data on coal mines. J. B. 

Reeside, Jr., visited the Eby party in the field during two or more 

field seasons and made fossil collections and identifications that are 

the basis for much of the stratigraphic classification. Work done 

from 1923 to 1926 was under the general supervision of W. T. Thorn, 

Jr., and from 1928 to 1947 under the general supervision of H. D. 

Miser.

STRATIGRAPHY

The exposed rock sequence, 13,500 feet thick, is of Late Cretaceous 

and Tertiary age, and includes chiefly thick formations of shale and 

of interbedded sandstone, shale, and coal. A generalized columnar

section of tke sedimentary rocks is shown in plate 18. The formations 

are described in ascending order.

CRETACEOUS (UPPER CRETACEOUS) ROCKS 

MANCO8 SHALE

The Mancos shale conformably overlies the Dakota sandstone and

conformably underlies the Mesaverde group. It is about 4,900 feet 

thick and consists chiefly of homogeneous dark-gray marine shale.

The basal beds of the formation are exposed at two places on Yampa

River at the west edge of Steamboat Springs, 9 miles east of the

mapped area, and in T. 6 N., R. 94 W., 23 miles west of the mapped

area. Exposures at the second locality are described by Hancock 

(1925, p, 11) as

consisting of at least 75 feet of bluish and dark-grayish shale, which weathers

out into more or less rectangular masses. The rocks exposed for some distance 

farther east and higher in the formation than those just described consist largely 

of dark-gray shale and calcareous sandstone. The following fossils were collected at this locality and are said by T. W. Stanton to belong to the Benton 

fauna, in the lower part of the Mancos shale:

Inoceramus fragilis Hall and Meek.

Inoceramus sp., near /. deformis Meek.

Prionocyclus wyomingensis Meek.
GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 151

Scaphites warreni Meek and Hayden.

Shark teeth.

On the south side of Yampa River in sec. 16, T. 6 N., R. 94 W., these dark 

calcareous and fossiliferous shale beds usually appear moist on the fracture 

planes and emit the odor of petroleum to a marked degree.

The lowest beds of Mancos shale that crop out in the mapped area 

lie about 300 feet above the base of the formation; they are exposed 

on the Williams Park anticline in the south-central part of the area 

and consist of dark-gray shale. Thin-bedded, fine-grained, fossiliferous, limy sandstone, estimated to be about 50 feet in thickness, 

crops out in Williams Park about 330 feet above the base of the formation. This sandstone is probably equivalent to some part of the 

Frontier sandstone. It is overlain by a sequence of limy shale interbedded with thin beds of platy, fossiliferous limestone, which is 1,300 

feet thick where it crops out in Williams Park and about 1,100 feet 

thick in the wells on the Tow Creek anticline. Although this sequence was not differentiated on the geologic map, it probably represents the Niobrara formation. Parts of the sequence are exposed in 

road cuts on U. S. 40 about midway between Steamboat Springs and 

Milner, as well as on Chimney Creek dome in Tps. 7 and 8 N., K. 

86 W. On Chimney Creek dome the beds consist of chalky, thinbedded to platy, very light-gray limestone to shaly limestone. This 

rock weathers into very light gray limestone chips which lie strewn 

on one or more of the low ridges that nearly encircle the crest of the 

dome. Included in the limestone are many fragments of a thinshelled fossil, presumably an Inoceramus, cemented to which are 

shells of Ostrea congesta. These beds of Niobrara age yield shows of 

gas, and they yield the oil that is being produced in the Tow Creek 

oilfield.

Most of the Mancos shale above the beds of Niobrara age consist 

of gray to dark-gray shale. However, several thin-bedded silty tan 

sandstone units, each 40 to 75 or slightly more feet thick, and some 

interbedded sandy shale and shale are included in the uppermost 

1,000 feet. The number of beds of sandy shale and sandstone increases upward within this 1,000-foot sequence. The main sandstone units form conspicuous ledges and hogbacks low in the 'slope 

below the sandstone cliffs of the basal part of the lies formation. 

Although two or three such sandstone units are present everywhere 

along the outcrop of the upper part of the Mancos shale, the individual units are believed not to persist throughout the area. Near 

Hamilton, 5 miles west of the mapped area, one of these sandstone 

units, which lies 800 feet below the top of the Mancos according to 

Hancock (1925, p. 11) and 930 feet below the top according to Sears 

(1924, p. 288), was named by Hancock (1925, p. 12) "the Morapos 

sandstone member" of the Mancos shale. This member was not 

positively identified in the mapped area, however.
152 CONTRIBUTIONS TO ECONOMIC GEOLOGY

The sandstone units in the -upper part of the Mancos shale are 

silty, in part shaly, very fine grained, and thin bedded, in contrast 

to the massive, less silty sandstone units of the overlying Mesaverde 

group. Moreover, the Tow Creek sandstone member the basal unit 

of the lies formation of the Mesaverde group appears to persist as a 

zone throughout the area; although this member is somewhat variable, 

it is a key bed lying directly above the contact of the two formations. 

A massive light-grayish-tan sandstone, which lies from 100 to 200 feet 

below the Tow Creek sandstone member and is particularly thick and 

well exposed north of Yampa River, is included in the Mancos shale. 

It is well exposed on the northwest side of Wolf Creek in the E% sec. 

23, T. 7 N., K. 87 W,; there it is 210 feet below the Tow Creek sandstone member and 50 feet or slightly more in thickness. This sandstone 

is conspicuously exposed on the east side of Tow Creek in the E^W^ 

sec. 32, T. 7 N., ft. 86 W.

Fenneman and Gale (1906, p. 22, pi. 2), Campbell (1923, p. 7), and 

Crawford, Willson and Perini (1920, p. 34-36) have included in the 

Mesaverde group the top 750 to 900 feet of beds assigned herein to the 

Mancos shale. However, in the adjacent area to the west, Hancock 

(1925, p. 15-17) placed these beds in the Mancos shale.

The Mancos shale crops out in a broad southeastward-trending belt 

of country along Williams Fork, which is south of the rugged country 

containing the Mesaverde group, and in a large tract in the northeastern part of the mapped area, which is a few miles east of the Wolf 

Mountain-Pilot Knob ridge. The area occupied by the Mancos is 

characterized by a roughly rolling topography.

MESAVERDE GROUT

The Mesaverde group conformably overlies the Mancos shale, 

It consists of thick beds of light-brown sandstone and some thick 

key beds of white sandstone interbedded with gray shale, sandy shale, 

and coal beds. The thickness of the group ranges from 2,750 feet in 

the eastern part of the mapped area to 3,450 feet in the western part. 

Its westward increase in thickness is due chiefly to a change of facies 

of the beds in the lower part of the Lewis shale, which directly overlies 

the Mesaverde. These beds consist of marine shale in the eastern half

of the area, where they are placed in the Lewis shale, and they change

westward into interbedded sandstone, sandy shale, and coal, and there 

are included in the Mesaverde group.

In the area adjacent on the west to the mapped area, the Mesaverde 

group was divided into two formations by Hancock (1925, p. 14), the 

lies formation below and the Williams Fork formation above. The 

two formations and their members are readily recognizable in the 

anapped area. The lies formation contains a thick sequence of ledgeiforming sandstone beds (pi. 16A) interbedded with sandy shale, shale,
GEOLOGY, MINERAL FUELS,. ROUTT AND MOFFAT COUNTIES, COLO. 153

and coal beds, and at its top, a prominent ledge-forming white sandv 

stone the Trout Creek sandstone member (pi. 16B). The Williams 

Fork formation is similar in general composition to .the lies formation, 

but its sandstone units are distributed differently. Its most prominent 

member is the Twentymile sandstone, which lies 900 to 1,1.00 feet above 

the Trout Creek sandstone member of the lies formation. Thick 

ledge-forming units of closely associated beds of sandstone characterize 

the entire Mesaverde group. Several of these persist throughout the 

mapped area. The sandstone beds consist chiefly of fairly well to wellsorted fine grains of quartz. Most of them also contain many very fine 

grains and some clay. The bedding is generally regular, and long 

wedge-shaped units of crossbedded sandstone are common.

Most of the persistent sandstone units appear to have been deposited 

on beaches or in shallow water near the margin of a large body of water. 

The thick white sandstone beds, such as the Trout Creek and Twentymile members, particularly, have features common to sands deposited 

on beaches. These two sandstone members and beds closely associated 

with them occur in sequences that are remarkably similar. At the 

base of each sequence is dark-gray to nearly black shale containing 

marine or brackish-water invertebrates. Above this is the main 

sandstone unit, a thick, light-gray to white, fine-grained, massive 

sandstone, 100 to 200 feet thick. This is overlain by a relatively thin 

unit, 10 to 30 feet thick, of interbedded sandy shale, carbonaceous 

shale, and locally, a thin bed or beds of coal. Next above is a white, 

massive sandstone similar in composition to the main sandstone unit, 

but commonly only 20 to 35 feet thick. It is overlain by a sequence 

of gray shale and sandy shale containing a bed of oyster coquina 

ranging from 1 to 3 feet thick. More interbedded shale and sandy 

shale are next above.

Fossil collections (Hancock, 1925, p. 17-20) show that marine, 

brackish-water, and fresh-water environments alternated during the 

time of deposition of the Mesaverde group. Such alternation suggests 

that oil or gas should occur in beds of the Mesaverde group in or near 

the mapped area where these rocks are deeply buried.

The Mesaverde group forms steep slopes and cliffs with bare ledges 

of sandstone. In many places the slopes and cliffs rise abruptly 1,000 

feet or more above the adjacent lowlands formed on the Mancos shale. 

Upward from the lower slopes and cliffs, lesser steep slopes and cliffs 

continue step-like to the top of the group. These features are particularly well developed in the Daton Peak quadrangle northeast of 

Williams Fork River (pi. 16A). There a strip of rugged country, 2% 

to 3)2 miles wide, developed on the Mesaverde group, .trends southeastward across the quadrangle and is called the Williams Fork 

Mountains. The rugged country continues from the Daton Peak, 

quandrangle southeastward to the southeastern corner of the mapped 

area, then trends northward across the eastern part of the mapped
154 CONTRIBUTIONS TO ECONOMIC GEOLOGY

area. Several large anticlines greatly modify the trend of the strip of 

rugged country, because they control the trend of the outcrop of the 

Mesaverde group. For example, in the south-central part of the 

mapped area a strip of rugged country swings several miles northward 

around the Sage Creek and Fish Creek anticlines, and in the eastcentral part it swings 12 miles or more southward around the Tow 

Creek anticline.

ILES FORMATION

The lies formation, in the lower part of the Mesaverde group, consists of a sequence of rocks about 1,500 feet thick. It is conformable 

with the Mancos shale below and the Williams Fork formation above.

The lower two-thirds of the formation, 1,000 to 1,100 feet thick,, 

consists of massive ledge-forming beds of light-brown, light-gray, and 

white sandstone interbedded with gray sandy shale, shale, and, in its; 

upper part, coal beds. This sequence forms rugged cliffs that rise 

high above the broad lowland formed on the Mancos shale. Such 

cliffs are particularly prominent in the Williams Fork Mountains 

north of the Williams Fork River (pi. 16A). Most of the coal beds

that are assigned to the lower coal group of the Mesaverde are in the 

upper part of this sequence. The thicknesses and composition of 

individual beds of sandstone within the sequence vary greatly laterally, but some sandstone units, or zones, persist throughout the mapped 

area. The composition and physical expression of the sandstone units 

are so similar that identification of individual beds within the sequence

was possible only by measuring stratigraphic sections in canyonsspaced only a few miles apart.

The upper one-third of the lies formation consists of a shale sequencecapped by a cliff-forming sandstone, which together are about 400 to600 feet thick. Coal of the lower coal group is distributed throughout 

the middle and upper parts of the formation. Four persistent sandstone beds in the lies formation deserve special mention as guides to^ 

correlation within the mapped area. They are (1) the Tow Creek

sandstone member at the base, (2) a double ledge-forming sandstonesequence 400 feet or more above the base, (3) a light-gray sandstone 

sequence of variable composition associated with the upper (no. 3)

coal of the lower group and situated about 900 to 1,000 feet above

the base, and (4) the Trout Creek sandstone member at the top of

the formation. Only the last of these has been separately mapped

for this report.

A stratigraphic section of the formation was measured in almost.

every gulch in the Baton Peak quadrangle that trends southward 

across the formation and enters Williams Fork. In some gulches the

sections were measured by planetable surveys, and in others they 

were merely sketched and the thickness of stratigraphic units was-- 

estimated. Exposures of the formation are relatively good in this-.
GEOLOGICAL SURVEY BULLETIN 1027 PLATE 16

A. LEDGES IN LOWER PART OF ILES FORMATION. 

North of "Williams Fork near Pagoda, Colo.

«. LEUGE OF THE TltOLT i;l«EKK s\lM)sLO:\K iVIKMHKK. 

North of Hayden Gulch in sees. 35 and 36, T. 5 N., R. 89 W., Colorado.

SANDSTONE LEDGES OF THE ILES FORMATION
GEOLOGICAL SURVEY BULLETIN 1027 PLATE 17

A. VIEW OF MOUNT HARRIS, COLO., LOOKING NORTHEAST ACROSS YAMI'A KI VEK VALLEY.

The ledge of the Twenlymile sandstone memher of the Williams Fork formation appears in upper part of

photograph.

II. CAST OF A DINOSAUR FOO'11'UI.NT. 

In the roof of the Wadge coal mine of the Victor-American Fuel Co. at Mount Harris, Colo.
GEOLOGY, MINERAL FUELS, ROUTT .AND MOFFAT COUNTIES, COLO. 155

part of the mapped area, and correlations of units from gulch to gulch 

were made with confidence. Good exposures of the formation in 

Jeffway, Berry, Hayden, and Long's Gulches, and in a few others, 

are accessible by roads.

Other stratigraphic sections were measured in the south part of the 

Mount Harris quadrangle, but these were spaced 4 to 8 miles apart. 

Those in Sage Creek and Fish Creek canyons are particularly well 

exposed and accessible. Following the measurement of these stratigraphic sections, others were measured near Oak Creek, near Bear 

River on the Tow Creek anticline, and on Wolf Creek where the units 

in the formation are somewhat different in character from those in 

the southern part of the mapped area. A few distinctive sandstone 

beds and some unique sequences of beds, however, occur here as well 

as in the southern part of the mapped area, making possible the 

identification of the several parts of the formation. The stratigraphic 

position of coal beds at Bear River and elsewhere, relative to the 

thick beds of coal in the lower coal group in the Oak Creek vicinity, 

was determined by comparing the graphs of the many measured 

sections. Beginning about 5 miles north of Yampa River and extending northward across the Pilot Knob quadrangle, the lies formation and the overlying Williams Fork formation are poorly and only 

partly exposed. The sequences were identified by comparing plotted 

sections of the parts of the formations exposed with the full-length 

sections measured in the area to the south. Most of the identifications are reasonably certain.

The upper one-third of the formation consists mostly of a poorly 

exposed shale unit, 275 or slightly more feet thick, containing some 

sandy shale, soft sandstone, and coal beds. The base of this sequence 

lies 1,000 to 1,100 feet above the base of the lies formation. Throughout the mapped area the shale unit lies between the ridges of underlying sandstone beds and the prominent ledge of the overlying Trout 

Creek sandstone, which marks the top of the formation. It forms a 

soil-covered lowland and is, therefore, not much exposed. Its general 

character and composition was determined from the character of the 

surface formed on it and from records of core drilling near Oak Creek, 

Mount Harris, and in the Williams Fork Mountains.

Tow Creek sandstone member. The Tow Creek sandstone member, 

a massive, cliff-forming, light-brown rock, is the basal unit of the 

lies formation. It is fine grained, well sorted, tightly cemented, and 

slightly calcareous, and its thickness ranges from 35 to slightly more 

than 125 feet. The rock is particularly prominent in Hayden Gulch, 

near the junction of the Hayden Gulch and Williams Fork roads. 

Here it is 125 feet thick. Huge blocks, 20 feet or more in diameter, 

have broken from the main ledge and are strewn on the floor of the 

gulch. This sandstone member forms a prominent brown ledge, or

345016 55 2
156. . CONTRIBUTIONS TO. ECONOMIC GEOLOGY :

series of ledges, in all gulches that cut through it directly northeast 

of Williams .Fork. However, it is not everywhere a single, massive 

.bed. In some places it consists of two or more beds separated by 

units of shale and sandy shale. The rock becomes so shaly in the 

vicinity of Oak Creek that its identity there as Tow Creek sandstone 

is questionable. The member forms a prominent ledge capping steep 

slopes on both sides of the Tow Creek anticline; it was here that 

Willson (Crawford, Willson, and Perini, 1920, p. 4-36) named the 

member "Tow Creek sandstone."

Double-ledge-forming light-gray and white sandstone. A light-gray 

and white sandstone 400 feet or more above the base of the lies formation appears as a double white ledge high in the rugged slopes of the 

Williams Fork Mountains; it is particularly conspicuous in the 

northeastern part of T. 4 N., R. 88 W. It served as an identifiable 

sequence in all complete sections of the formation that were measured. 

In Searcy Gulch, in T. 5 N., R. 90 W., this sandstone unit is 130 or 

slightly more feet thick and is 460 feet above the base of the lies 

formation. It forms two prominent ledges in the slopes on the 

north side of the gulch. In Hayden Gulch it is 225 feet thick, 400 

feet above the base of the formation, and forms three prominent 

ledges in the south-facing slopes. In Fish Creek canyon, it is con^- 

spicuously exposed on the north side of the canyon where it is 250 

feet thick and 415 feet above the base of the formation. The unit 

forms a single light-gray to white ledge in the flatiron-shaped hill east 

of Cheney Creek, a little more than 1 mile north of Milner, and is 

conspicuous as viewed from. U. S. 40. Here it is the key bed for 

determining the amount of displacement along a northwestwardtrending fault that passes a few hundred feet south of the flatironshaped hill (pi. 19).

Sandstone sequence associated with the no. 8 coal beds of the lower

groit-p. -A. sandstone sequence about 1 ,OOO feet above the base of the

lies formation is probably the most useful preliminary guide to coal

within the lies formation, because valuable Coal kedg &TG aSSOClated* 

with. it. It is generally light gray to white and forms fairly conspicuous ledges throughout much of the area. At many places in

the Williams Fork Mountains the sandstone unit consists of two to

three thick beds of light-gray to white sandstone, whose total thickness is ISO feet or more. It is exposed, in Hayden Gulch, as several

massive light-gray beds, each about 10 to 40 feet thick and separated

by interbeclclecl soft sandstone and. shale. Pwo massive beds are 

particularly conspicuous here. The coal bed mined at the luce

(old Weber) mine, on the east side of the Hayden (Men road, is

above the uppermost massive sandstone bed, and the coal bed mined 

at the Sun (old Green) mine, on the west side of the road, is below 

the lower massive sandstone bed (see pis. 20 and 21). Ledge-forming
GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 157

white sandstone beds appear at about these positions in nearly all 

.gulches where stratigraphic sections were measured. However, the 

number of sandstone beds, and the position of the most conspicuous bed 

relative to other beds in the sequence, varies from place to place. 

Accordingly, less confidence is placed in the precise correlation of 

this sandstone sequence, bed for bed, throughout the mapped area 

than in the correlations of some of the others.

A thick sandstone in about the same stratigraphic position as the 

one in Hayden Gulch forms a prominent hogback 425 feet below the 

top of the Trout Creek sandstone member in Fish Creek canyon. 

There it is underlain by two coal beds in which small mines were 

opened years ago. A white sandstone, in about the same.stratigraphic 

position, is exposed in the steep slopes on the west side of Oak Creek, 

about 600 feet below the top of the Trout Creek sandstone member, 

and above the several coal beds in the lower coal group. At Bear 

River, a white sandstone about 30 feet thick that probably represents 

a part of the same sandstone zone, crops out about 480 feet below the 

top of the Trout Creek sandstone member and about 70 feet above 

the thick coal bed that was mined in the abandoned Bear River mine.

Trout Creek sandstone member. The Trout Creek sandstone member 

of the lies formation is the most, reliable key bed in the entire stratigraphic sequence that is exposed in the mapped area. It is a finegrained, massive, cliff-forming, white sandstone about 100 feet thick. 

Except for large tracts of the Pilot Knob quadrangle that contain 

only a few outcrops, the Trout Creek member has been identified 

throughout the mapped area and far beyond. It is typically exposed 

on the north side of U. S. 40 at Bear River, on both sides of the road 

in Hayden Gulch (pi. 16B), and at many other places. Its top is 

the horizon on which the structure contours are drawn in plate 19. 

Hancock (1925, p. 13-14) identifies the Trout Creek sandstone member throughout the Axial and Monument Butte quadrangles, which 

are adjacent on the west. The "white rock" that was identified by 

Gale (1910) along the Grand Hogback from a locality near Meeker, 

Colo., to Newcastle is equivalent to the Trout Creek member, according to Hancock (1925, p. 13-14). The Trout Creek sandstone member 

was named by Fenneman and Grale (1906, p. 26) from exposures near 

Trout'Creek on the northeast side of Twentymile Park, which is in 

the. eastern part of the area.

WIIIIAMS FORK FORMATION

The Williams Fork formation includes all beds between the top of 

the Trout Creek sandstone member and the base of the Lewis shale. 

The formation is conformable at its base and top. Its thickness 

ranges from 1,100 feet near Mount Harris to nearly 2,000 feet at the 

west margin of the area. The formation includes a lower unit about
158 CONTRIBUTIONS TO ECONOMIC GEOLOGY

1,000 feet thick, consisting chiefly of shale, thin sandstone beds, 

sandy shale, and the several coal beds of the middle coal group; a 

middle unit of massive white cliff-forming sandstone about 100 to 

200 feet thick, called the Twentymile sandstone member; and an 

upper unit of interbedded sandstone, sandy shale, shale, sandstone, 

and the coal beds of the upper coal group.

Lower unit. The lower unit of the Williams Fork formation is 

important because it contains several thick coal beds of the middle 

coal group. These beds include the Wolf Creek, Wadge, and Lennox 

beds in the Mount Harris and Oak Creek districts, and 3 to 5 bed& 

that are greater than 5 feet thick and other thinner beds in the Williams Fork Mountains district. Logs of core holes and outcrops show 

that much of the lower half of the unit consists chiefly of soft sandstone, thin-bedded sandstone, sandy shale, coal beds, and thin beds 

of dark-gray to black shale. Although the upper half of the unit 

contains a few beds of sandstone, it consists chiefly of shale. In 

most places the coal-bearing part of the unit commonly forms fairly 

steep slopes above the Trout Creek sandstone member. In the 

Williams Fork Mountains area these beds form red, rocky slopes (the 

color results from the natural burning of the outcropping coal). At 

several places in the mapped area, long dip slopes are formed by 

interbedded thin sandstone and sandy shale beds that lie 50 to 75 

feet above the Wadge coal bed. At these places it may be possible 

to mine the Wadge and Lennox beds by stripping. In most places 

the upper half of the unit forms a broad lowland between the coalbearing beds below and the ledge-forming Twentymile sandstone 

member above.

Twentymile sandstone member. The Twentymile sandstone member 

of the Williams Fork formation is similar in composition, color, and 

habit of outcrop to the Trout Creek sandstone member of the lies 

formation, from which it is separated by 900 to 1,100 feet of beds.

It is a massive, white, ledge-forming sandstone about 1OO to 2OO feet 

thick and forms a prominent white ledge at the top of a steep slope

rising above the broad lowland, The surface of the lowland is characteristic of that which forms on beds.underlying the sandstone (pi. 17A).

Throughout most of the area, the Twentymile and Trout Creek sandstone members form two excellent key beds for mapping. In tha 

western part, however, the Twentymile sandstone member is divided

into Several beds, and is closely associated with other ledge-forming

white and light-buff sandstones.

Upper unit. The upper unit of the Williams Fork formation lies

above the Twentymile sandstone member. It has the greatest range 

in thickness of any part of the formation. In the vicinity Of Moittlt

Harris, Twentymile Park, and Fish Greek, the thickness of the unit
GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 159

is about 200 feet. Here the unit consists of beds of sandstone, sandy 

shale, dark-gray shale, 'and one coal bed about 3 feet in thickness. 

It is overlain by gray shale beds of the Lewis shale. Westward, 

however, the unit thickens by additions to its top, and at the western 

edge of the mapped area it is about 850 feet in thickness. The lowermost beds of shale of the Lewis change westward to sandy shale, 

sandstone, and coal beds, and are there included in the Williams 

Fork formation. At Dry Creek, for example, several workable coal 

beds, including the thick Dry Creek coal bed, are present in this upper 

unit of the formation. In places, the upper unit includes several 

massive white sandstone beds that resemble the Twentymile member. 

One of these, which lies about 25 to 50 feet above the Twentymile 

member, is well exposed on Dry Creek. Another, near the top of the 

unit, forms conspicuous ledges near the west margin of the area and 

extends many miles beyond the area; it is particularly well exposed 

in T. 6 N., R. 92 W. (Hancock, 1925, pi. 2A).

LEWIS SHALE

The Lewis shale consists chiefly of dark-gray to bluish, homogeneous 

marine shale. It is conformable with the underlying and overlying 

formations. The formation crops out in a wide, curving strip of 

rolling, treeless country that crosses the north-central and westcentral parts of the area, and in a narrow, curving neck that connects 

the main area with Twentymile Park in the southeastern part of the 

area. The thickness of the formation is difficult to determine accurately, because the beds have a low dip and the outcrops of the basal 

and tops beds are many miles apart. North of Yampa River in the 

north-central part of the area the thickness is estimated to be 1,900 

feet, and in the western part it is about 1,500 feet or less.

The lower and upper boundaries of the formation are not sharply 

defined and vary in stratigraphic position across the area. In the 

eastern part of the mapped area the lower boundary of the Lewis 

shale is drawn about 200 feet above the top of the Twentymile sandstone member of the Williams Fork formation, and at the west margin 

of the area it is drawn about 850 feet above the Twentymile member. 

The boundary between the Williams Fork formation and the Lewis 

shale is drawn at the contact of beds that consist dominantly of sandstone, sandy shale and coal below with beds that are dominantly 

gray shale above. Inasmuch as the lowermost beds of the Lewis 

shale change progressively westward from relatively homogeneous 

shale to sandstone, sandy shale and coal beds, the boundary rises 

stratigraphically westward.

The upper boundary of the Lewis shale shown on the map is based 

on Eby's field investigation in 1923 and 1924. According to Eby, 

this boundary near the west edge of the mapped area is probably
160 CONTRIBUTIONS TO ECONOMIC GEOLOGY

higher, stratigraphically, than it is north of Yampa River in the 

north-central part of the area. In the westernmost part of the area 

the boundary is drawn below a massive sandstone that forms a run 

rock. This rim rock is conspicuous half a mile north of Craig. North 

of Yampa River in the central part of the mapped area, a sequence 

about 500 feet thick, consisting of beds of lenticular sandstone, 

sandy shale, shale, coal, and coaly shale, forms a transition zone 

above the main body of marine shale of the Lewis shale. Much of 

this sequence lies stratigraphically below the rim rock sandstone of 

the western part of the area, according to Eby's tentative correlations. 

The boundary between the Lewis shale and Lance formation north of 

Yampa River was drawn at the base of a coarse-grained sandstone, 

which is at the base of the sequence and 50 feet below a thick coal bed 

locally called the Lorella coal. The boundary was drawn arbitrarily 

because lenticular beds of sandstone and sandy shale are present 

below it. Marine invertebrates collected from the Lewis shale in the 

area adjacent on the west to the mapped area were identified by T. W. 

Stanton as probably equivalent in age to the upper part of the Montana 

(Hancock, 1925, p. 21).

LANCE FORMATION

The Lance formation, which is about 1,050 to 1,500 feet thick, 

conformably overlies the Lewis shale. The formation crops out in 

the northwestern quarter of the mapped area, where it was investigated by Eby. It consists of interbedded gray shale, light-buff and 

light-tan, soft, fine-grained sandstone, and a few coal beds. Of thft

coal beds, the Kimberley is the only one in the formation that IS Of 

much economic value. In the westernmost part of the area a thick, 

ledge-forming, white to gray sandstone lies at the base of the formation, 

and a thick, coarse-grained white sandstone is at the top, The basal

sandstone forms a rim rock half a mile north of Craig, and the upper 

sandstone forms a rim rock 3 miles north of Craig. North of Tampa 

River, in the north-central part of the mapped area, the Lance formation extends stratigraphically lower than in the westernmost part.

This relationship is discussed with the description of the Lewis shale. 

The position of the upper boundary of the formation, as shown on

the geologic map, is uncertain because the boundary is concealed 

nearly everywhere. Little data as to the attitude of the rocks are 

available. Eby drew a nearly straight northeastward-trending line

across the map to represent the approximate pOSitM Of the boundary,

Although the line was later adjusted to the topography, its position is 

largely hypothetical.

Marine invertebrates of Fox Hills age collected at the top of the 

basal sandstone by Hancock and T. W. Stanton, and later by Reeside 

and Eby, indicate that at least the lower 250 feet of the formation is
GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 161

more closely related to the Lewis shale than to the overlying freshwater deposits. For convenience in field mapping, however, the 

boundary between the Lewis shale and Lance formation was drawn 

at the base of the sandstone in the western part of the area, and at 

the base of the transition beds near Hayden, as discussed in the 

description of the Lewis shale.

TERTIARY ROCKS 

FORT UNION FORMATION (PALEOCENE)

The Fort Union formation overlies the Lance formation and consists of interbedded brown sandstone, gray shale, and coal beds. The 

formation is similar to the Lance in general aspect, but differs from 

it considerably in details. The sandstone beds are coarser, the shale 

is prevailingly a lighter gray, and there are more ferruginous layers 

in the Fort Union than in the Lance. Fresh surfaces of the sandstone 

are speckled with white. At several horizons coal beds are present 

and some are locally quite thick. A conglomerate lies at the contact 

with the Lance formation; however, there is little clear local evidence 

of erosion. The age of the formation is indicated by fossil leaves.

The thickness of the Fort Union formation cannot be directly 

measured anywhere in the area, but on the basis of data assembled 

during the mapping it is estimated to be about 1,400 feet.

The position of the upper and lower boundaries, as shown on the 

geologic map, are tentative. Because the boundaries are concealed 

in most places, Eby drew nearly straight lines across the map to 

indicate them. Later, the lines were adjusted to the topography.

WASATCH FORMATION (EOCENE)

The Wasatch formation consists of coarse brown sandstone, or grit, 

interbedded with gray and red clay shale. The contact with the 

older beds is not exposed in the area studied, and its character can 

only be surmised. North of the area, in Colorado and southern 

Wyoming, the contact of the Fort Union and Wasatch formations is 

sharp and unconformable. The highly colored beds of the Wasatch 

contrast greatly with the more somber strata of the underlying 

Fort Union. The thickness of the Wasatch formation cannot be 

determined in the mapped area, although it was estimated by Eby 

to be somewhat greater than 1,000 feet.

BROWNS PARK FORMATION^) (MIOCENE OR PLIOCENE)

A deposit of semiconsolidated white tuffaceous sand covers much 

of the area above 8,500 feet. Most of the material is coarse sand, 

but beds consisting of rounded pebbles and cobbles as much as 2 

inches or slightly more in diameter are present. Although no measurement was made, the sand was estimated to be 200 to 300 feet thick
162 CONTRIBUTIONS TO ECONOMIC GEOLOGY

on the south margin of the area. None of these deposits is shown on 

the geologic map. The general composition and character of the 

white sand deposits are similar to the Browns Park formation of late 

Miocene or Pliocene age. The Browns Park formation is widespread 

in northwestern Colorado and has been mapped only about 5 miles 

west of the area near Craig (Sears, 1924, pi. 35, p. 295).

QUATERNARY(P) BOCKS, UNO CONSOLIDATED SUBFICIAL DEPOSITS

Unconsolidated white sand, resulting from the disintegration of the 

Browns Park formation(?), has been transported down the slopes 

and now covers much country at lower levels, particularly in the 

northwestern and southwestern parts of the area. In a few places 

the sand is fairly well consolidated and appears as bedded rock. The 

most conspicuous occurrence of this type is in the valleys of Smith 

and Dry Creeks near the center of T. 8 N., R. 86 W., and is shown on 

the geologic map. A similar occurrence of coarse white sand overlying 

Mancos shale has been cut through by Yampa River half a mile south 

of Phippsburg.

Basalt boulders intermingled with white sand and cobbles of a 

great variety of rock form a thin veneer on most high divides, particularly in the southwestern and northern third of the mapped area. 

Slide rock occupies the surface at many places; it is particularly 

extensive on the northern slopes of the Flat Tops near the south 

margin of the area, and in the SW% sec. 3, T. 3 N., R. 89 W., includes

a prominent hill capped by basalt, These deposits are not shown on

the geologic map.

A rolling upland is present in the vicinity of Eddy School in the

northwestern part oi T. E N., R. 85 W., and the southwestern part of 

T. e N., R. 85 W., in which the bedrock is covered by a mantle, at

least 75 feet thick, of boulders and gravel of granite, gneiss, schist,

quartz, and other rocks (Fenneman and Gale, 1906, p. 31). Most of 

tMs material iS Unconsolidated, Some beds of micaceous clay and 

sandstone are interbedded with the boulders and gravel. The age of

the deposit is uncertain, tout it is not unlikely utx«,t it is of ^Pleistocene

age.

sat, sand, and boulder deposits form terraces in the yaiieys at

several altitudes above the larger streams; these terraces are not shown on ine geologic map. ^n ^ v**« ~^~~^.~ _ ^^.^.a ty .

narrow belt of oouluers, gravel, sand, and silt. It is shown as

alluvium, on the geologic map, along the courses of the larger streams

 where the belt is wide enough to Toe mapped conveniently on the

scale of the map. Such deposits occupy the flood plains of the

streams.
GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 163

IGNEOUS ROCKS

GENERAL FEATURES

Igneous rocks of the area consist of dikes that are 2 to 50 feet 

thick, sills that are a few feet to 300 feet thick, and a few plugs. 

Basalt flows cap the Flat Tops, whose northern margin occupies two 

small tracts at the south boundary of the mapped area. Most of the 

dikes, sills, and plugs are in the northeastern quarter of the area. 

The most prominent are Sand Mountain in T. 7 N., Rs. 86 and 87 W., 

Pilot Knob in T. 8 N., R. 87 W., Hooker Mountain in T. 7 N., Rs. 87 

and 88 W., Wolf Mountain in T. 7 N., R. 87 W., the Rim Rocks in 

Tps. 8 and 9 N., R. 86 W., and Sand Mountain in T. 9 N., R. 86 W. 

In the western part of the area, Breeze Mountain in T. 6 N., R. 90 W., 

is prominent. Baton Peak in T. 5 N., R. 89 W., is capped by a basalt 

flow.

C. S. Ross of the Geological Survey, who examined specimens of the 

dikes, sills, and plugs, has grouped the rocks into three general types: 

basalt, latite-trachyte, and lamprophyre. The most widespread rock 

is olivine basalt, according to Ross, although olivine-analcite basalt 

and olivine-free basalt also occur. Olivine basalt forms the main mass 

of Pilot Knob and the dikes and sills associated with it, the mass on 

Hooker Mountain, the main northwest-trending dike of Wolf Mountain, the Rim Rocks sill, the sills on Elkhead Creek and in Agner 

Mountain, and most other dikes and many of the sills. In general, 

the sills are somewhat coarser in texture than the dikes. The sills 

on the Chimney Creek dome in Tps. 7 and 8 N., R. 86 W., are 2 to 8 

feet thick and consist of olivine-free basalt. The olivine-free basalt is 

lower in ferro-magnesian minerals and is lighter gray than the olivine 

basalt, which is dark gray to black.

The latite-trachyte rocks constitute the main mass of Sand Mountain in T. 7 N., Rs. 86 and 87 W., and also form Sand Mountain in T. 

9 N., R. 86 W., near the northeast corner of the area. The thick sill 

in Quaker Mountain in sees. 27, 28, 33, and 34, T. 9 N., R. 87 W., is of 

similar composition. The three short dikes northwest of Elkhead 

River in sees. 16 and 17, T. 9 N , R. 87 W., the two dikes in sees. 22 

and 23, T. 9 N., R. 87 W., the small plug in sec. 10, and the dike in 

sees. 10 and 14, T. 7 N., R. 86 W., are lamprophyres.

Late in 1949 a well that was drilled on Chimney Creek dome in sec. 

4, T. 7 N., R. 86 W., entered igneous rock, possibly a sill, at a depth of 

1,797 feet, and was drilled 181 feet into it. A cored sample obtained 

11 feet above the bottom of the hole was examined in 1950 by C. S. 

Ross, and he reported that the rock "has a very fine grained groundmass; it contains about 45 percent of plagioclase and 24 percent of 

potassic feldspar. The rock contains 71.85 percent of Si02, indicating 

that it is rather silicic, and so must be moderately high in quartz.
164 ' / CONTRIBUTIONS TO, ECONOMIC GEOLOGY

The rock would, therefore, seem to be best described as a granodiorite 

or perhaps as a quartz diorite."

METAMORPHISM

Contacts of the larger igneous bodies with sedimentary rocks were 

not observed, but at some places strata within a few feet of dikes that 

are 4 to 15 feet thick show only a slightly increased induration. At 

other places the alteration is somewhat more pronounced. Beds in 

the Lewis shale, which overlie basalt sills 6 to 8 feet thick in sec. 1, T. 

7 N., R. 88 W., have been indurated through a thickness of 5 to 8 

feet. Sills of olivine-free basalt, 2 to 8 feet or more thick, that crop 

out on the Chimney Creek dome have altered the adjacent shale to a 

reddish-brown color throughout a zone 2 to 10 feet thick. The material very near the contact weathers into hard, glazed chips. Shale 

is somewhat altered for a distance of 2 to 3 feet on each side of a thin 

dike in the SEX sec. 14, T. 8 N., R. 88 W. A thin dike of basalt, 

which was not observed at the surface but which cuts the Wadge coal 

bed in the Victor-American Fuel Co.'s Wadge mine in sec. 9, T. 6 N., 

R. 87 W., has coked the coal for 9 feet on each side of the dike.

In the middle 1920's, the Moffat Coal Co. prospected, by core 

drilling and by driving tunnels, a fairly large tract on Cottonwood 

Creek in T. 8 N., R. 87 W., that contains thick sills of basalt closely 

associated Stratigraphically with the coal beds of the middle coal group. 

Many of the results of this investigation ¥616 described by G. C. 

McFarlane (1929), chief engineer for the Moffat Coal Co., and the 

following data were obtained from his report.

The core drilling showed that the thickness of the sills in the area

prospected ranges from 10 to 300 feet. In the middle of a sill the basalt 

is homogeneous and appears to represent a single intrusion; in places 

near the margin the sill IS split into Several thin sheets. In general,

the sills are parallel with the bedding, but in places cut across the 

bedding.

McFarlane cites the record of a core-drill hole that penetrated a 

sill 225 feet thick, lying between the Wadge and Wolf Creek coal beds,

and the records of seven drill holes located within a radius of threequarters of a mile of this hole. The seven holes penetrated the 

geQUeBCe containing these two coal beds, but did not enter basalt.

The interval between the two coal beds in tu6 SfiVeD drill hOlOB COHtaining undisturbed strata ranges from 132 to 147 feet, and in the 

drill hole containing the sill, 374 feet; the sill accounts for 225 feet of 

this thickness. If the thickness of the sill is subtracted from the total

interval found in this hole, the thickness of the sedimentary sequence 

between the two COal beds IS 149 feet, Which is 2 feet more than its 

thickest development in the seven holes containing no basalt.
GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 165

In another core-drill hole, the basalt sill is split into six thin layers 

lying within the sedimentary sequence between the Wolf Creek coal 

bed and a lower coal bed, known locally as the small anthracite bed. 

This hole penetrated a total thickness of 84 feet of basalt and 26 feet 

of sedimentary rocks. The thickness of the sedimentary rocks 

between the two coal beds ranges from 35 to 41 feet in six drill holes 

containing no basalt that were bored in the adjacent area. Thus, 

except for 9 to 15 feet, the increased interval between the two coal 

beds appears to be accounted for by the presence of the sill; possibly 

the basalt assimilated a total thickness of 9 to 15 feet of the adjacent 

sedimentary rock. The interval between the two coal beds, however, varies 6 feet in the six drill holes that penetrated no basalt. It 

is possible, therefore, that the 9- to 15-foot thickness represents a 

normal variation of the interval between the two coal beds. 

McFarlane identified in the records of several core-drill holes the 

small anthracite coal bed and the upper Block mine coal bed 

which underlies it. In three holes that penetrated no basalt the 

interval between these two coal beds is 46 feet, and in one hole that 

penetrated a sill 142 feet thick the interval is 184 feet. The total 

thickness of sedimentary rocks between the two coal beds in the hole 

containing the sill is 42 feet, which is only 4 feet less than in the 

holes that penetrated no basalt.

These data suggest that the sills intruded the sedimentary sequence 

chiefly by spreading apart the strata rather than by assimilating the 

sedimentary rocks.

The metamorphic effect of the sills on the coal is variable, particularly near the margins of the sills. The least variation was 

noted above and below the main bodies or central parts of the sills. 

Here, in general, the coal beds lying above and below the sills in 

sequences ranging from one-fourth to one-third the thickness of the 

sills were changed from bituminous rank to anthracite. For example, 

the record of a core-drill hole near the east margin of a sill, 307 feet 

thick, shows a coal bed 30 feet below the sill that was altered only 

slightly. McFarlane suggested that here the basalt "was near the 

end of its journey" when it had intruded to this point and had perhaps 

already partly cooled.

Where drill holes show the thick Wolf Creek coal bed to be only a 

short distance above or below a thick sill, the coal of this bed was 

metamorphosed to a meta-anthracite. The meta-anthracite appears 

to have been a poor conductor of heat, for where the Wolf Creek 

meta-anthracite is directly above a sill, the coal beds that lie above 

the Wolf Creek bed were altered less than coal at the same distance 

below the sill; and where the Wolf Creek meta-anthracite is directly 

below the sill, coal beds that lie below the Wolf Creek were altered
166 CONTRIBUTIONS TO ECONOMIC GEOLOGY

less than coal beds at the same distance above the sill. Analyses of 

the coal suggest that sandstone and shale are much better conductors 

of heat than coal.

The core-drill holes revealed that anthracite is present as far below 

the central area of a sill as above it, but evidence of metamorphism 

extends farther upward than downward. The best anthracite was 

found at a distance above and below a sill equal to one-seventh the 

thickness of the sill. One coal bed occurring at this distance above 

a sill has a heating value of 13,733 Btu; another, occurring at this 

distance below the sill, is the strongest coal found, having a compressive strength of 8,142 pounds per square inch. The compressive 

strength of unaltered coal from the middle coal group is 3,664 pounds 

per square inch. It is noteworthy that the coal having the high compressive strength has "nearly the same proximate analysis as anthracite from the Mammoth bed, Lansford, Pennsylvania, and also the 

same specific gravity, 1.563. Both these coals carry only 0.6 percent 

of moisture on the air-dried basis." (McFarlane, 1929, p. 3.)

The coal beds penetrated by the core drill showed a progressive 

increase in density as a sill was approached.

Temperature tests were made by McFarlane and the U. S. Bureau 

of Standards on samples of metamorphosed and unaltered coal from 

this area and from other coalfields. These data and comparisons 

made with the coal associated with the basalt sills on Cottonwood 

Creek suggest that a coal bed situated 1 foot from a basalt sill probably reached a temperature of 1,000°C, that high-grade anthracite 

having 94.5 percent fixed carbon probably reached a temperature of 

000°C, that semianthracite reached a temperature between 350°C 

and 400°C, and that tlle bituminous coal of the area probably remained unaltered until its tempeTatuTe exceeded 160°C.

Compiled and compared thicknesses Of Unmetamorand metamorphosed COal from the same beds. His data

suggest that a coal bed Shrinks in thickness from 29 to 33 percent 

when it passes from bituminous rank tO anthracite, and* that it 

shrinks in thickness 50 percent when it passes from bitunimOUS rank

to meta-antnracite.

ivLany Of tne data from the extent** Investigation made by the 

Moff&t Coal Co- on c°tto^wood Creek are summarized graphically 

by McFarlane in E Columnar section wnioix is ^produced in part 

herein as figure 39. The column is generalized; actually, meta^or_ 

phism in individual coal beds varies considerably from place to place. 

For example, the Yertical zonation, a metamorphlc effect Of the basalt 

sills, is not nearly as uniform aS Suggested in the section. Prospect 

tunnels driven in metamorphosed coal on Cottonwood Creek showed 

that the metamorphism of a coal bed is not uniform. The rank of the 

coal changes laterally in short distances.
GEOLOGY, MINERAL FUELS; ROUTT'AND MOFFAT COUNTIES, COLO. 167

Estimated temperature Fixed, carbon

In degrees C percent

Feet 230

400 -

380 -

360-

340-

320 -

300 -

280 -

260 -

240 -

220 -

200 -

180 -

160 -

J40 -

J20 -

100 -

80 -

60 -

40 -

20 -

300

400

600

900 '

1

900

600

400

300 0-

230

ZONE OF ALTERED BITUMINOUS

ZONE OF SEMIBITUMINOUS

ZONE OF SEMIANTHRACITE

ZONE OF ANTHRACITE

ZONE OF META-ANTHRACITE

' \*AV « 4 7 *-'VT v »'1J i w " " w *r «

V''*' l'"'tvV<'XX«' 4 V* >-V?AV ; Sv^x <:; ; V r %,,/; ><: > *>v ;// <*.V<^!i.,raV^V* > rj

l' V- A /,V;*;'>V,«r> . **;

;<V<%Y.,V>V/><;' -; w

l' r ''''-l'> 1A*'|CJ "(,<»*«"*' » 'VI

V /* .;- 5 «*-;-. ;-,-,, v-' «v« <->v '- > -'rC''' » J * < f* > g »

TV, ri >/ r 4-lv"-> '-'-''T^ ^ » *

-,/-' V< -"'r»-/-'-r^ v'?^

> » . " ! < i. * , * ., 1 . * » - .

-\v ;:>v>v>;v/: r^:

%"*! > /OLIVINE BASALT SILL ' * r 4

 'V ,V,V"v>'-I» -'^< ' w *

* " 1 «l < T >* * «').>''» » " * i *. > "*V.i rr,4 »>!>r- * tr ",*<>; >/'« v fc r .»** ' ;!:*> >*r- - "»-*:"* " v v/.v^-v^'V^*//:; -:-: :'X-;::«:^v,,:«.v^ :>v

/ "**< « i4 **"**« ? "** -'r*

' v^' j ;'%>//, ; ;'4>rv/. * 5;

"V** 1 ** >* *'/ *'<*> "V* 4 * W 7< X

ZONE OF META-ANTHRACITE

ZONE OF ANTHRACITE

ZONE OF SEMIANTHRACITE

 >. ZONE OF .SEMIBITUMINOUS

ZONE OF ALTERED BITUMINOUS

-U.j..., - .^_____ .^^^ .^^ ________ -r--_ ^.-.-.IM ^-|r____ ^T^

 54. 50

 60. 31 

 68.'65

 83. 00

 88. 21

 93.80

 94. 80

 95. 20

 95. 40

 94. 94

 89.40

 81. 50

 67. 70

 61. 60

 54. 50

Specific

. gravity

131

1.29 

133

1.41

1.42

1.55

L58

L7I

1.90

1.77

1.54

136

134

L29

1.28

L30

FIGURE 39. Generalized columnar section showing zones of metamorphlsm of coal above and below a sill 

' In the Cottonwood Creek area, Colorado.
168 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Prospecting by drilling and by driving tunnels in coal was carried 

on in the area of the Rim Rocks in Tps. 8 and 9 N., R. 86 W., in the 

1890's, many years before the prospecting on Cottonwood Creek. 

The outcropping edge of the sill at Run Rock suggests that the sill 

ranges from 75 to 100 feet or slightly more in thickness. The coal 

beds that were investigated lie above the sill. Detailed data concerning the results of this prospecting are not available, but the 

meager information contained in drillers' logs of the holes indicates 

that metamorphism extends upward from the sill with variable effect 

through 70 to 80 feet of strata. Only the lowest beds of coal wer« 

changed to semianthracite or anthracite rank.

The downward' metamorphic effect of a thick sill on Elkhead Creek 

in sec. 25, T. 9 N., R. 88 W., was investigated by Eby (1925, p. 250). 

Here a bed of coal, 26 feet below the base of the sill, which is about.

200 feet in thickness, has been altered from subbituminous rank to 

anthracite; a bed of coal 44 feet below the base of the sill has been 

altered to semianthracite.

It is possible that the large Sand Mountain intrusion on Tow Creek 

has altered the crude oil in the north Tow Creek pool. The north 

Tow Creek pool is only 3,000 feet southwest, and the south TowCreek pool is 2 miles southwest of the outcrop of the intrusive body. 

Analyses of the crude oils from the pools, made by the Bureau of 

Mines Hempel method, show as follows: 1 "The crude in the north 

Tow Creek pool contains much more naphthenic and aromatic compounds than the crude in the south pool, The average of the correlation index numbers of the crude from the north pool is 39 contrasted 

with an average of 31 for the crude from the south pool. The gasoline 

and naphtha content of the north pool's crude is 15 percent and of 

the south pool's crude is 30 percent."

The API gravity, sulfur content, and residuum of the oil from the 

north Tow Creek pool is 27.2 degrees, 0.32 percent, and 39.5 percent,

respectively, and these features of the oil from the south pool are

36.2 degrees, 0.18 percent, and 23.3 percent, respectively. "The

large difference in the composition of tne crudes in the south and

north pools of the Tow Creek field is noteworthy inasmuch as the two

pools occur in tne same formation, the Niobrara shale, on the Sftme

anticline and are only 1^ miles apart." 2 The reservoir beds of

Niobrara age, in these two pools, consist of limy shale and shaly limestone. It was suggested by these authors that it may be that the

crude of the north pool was at one time similar to that of the south 

pool, and that its lighter, more volatile constituents were driven off

v i Bass, N. W., Smith, H. M., and Ohrlstenson, H. E., Geologic relationship of crude oils in the Tow 

Creek, Wilson Creek, lies, and Moflat fields, Colorado. Unpublished paper presented at annual meeting 

of Am. Assoc. Petroleum Geologists at Denver, 1942. 

> Bass, N. W., Smith, H. M., and Christenson, H. E., op. cit.
GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 169

by the heat from the intrusive body that occupies a large area about 

half a mile north of the oil pool.

"However, the difference in composition between the crudes of 

these two pools is not so great as the differences between crudes in 

closely spaced pools * * * in oil-bearing zones in a region containing 

no intrusions in Oklahoma." 3

STRUCTURE

The area described in this report lies in the southeast synclinal 

prong of the Washakie structural basin of south-central Wyoming. 

In Colorado, the syncline is bordered on the east by the Park Range 

a large anticline and on the southwest by the Axial Basin anticline 

(American Association of Petroleum Geologists, 1944). The axis of 

the syncline extends southeastward across the area mapped, passing 

half a mile east of Hayden.

The general structure of the rocks is shown by reconnaissance structure contours on plate 19. The regional synclinal structure is modified 

by many folds, particularly in the eastern and southern parts of the 

mapped area. The largest of these is the Tow Creek anticline, an 

asymmetrical fold that trends northeastward in the east-central part 

of the area. The small Tow Creek oil pool and the abandoned north 

Tow Creek pool are on the anticline. Most of the faults shown on 

the anticline are revealed by the outcropping beds of sandstone in the 

Mesaverde group and in the upper part of the Mancos shale. Many 

of the faults near Bear River and Mount Harris have been located 

through the mining of the coal beds.

The Wolf Creek dome, 3 miles northwest of the Tow Creek anticline, 

is on an extension of the Tow Creek anticlinal axis but is separated 

from the anticline by a structural saddle. A mass of igneous rock 

that forms Sand Mountain has been intruded into the sedimentary 

rocks on the south flank of the Wolf Creek dome, and several dikes 

are present in other parts of the dome. The attitude of the beds near 

their contact with the igneous mass, and the fact that the crest of 

the dome is some distance from the igneous body, suggest that the 

dome was formed .before the intrusion. The Chimney Creek dome, 

in Tps. 7 and 8 N., R. 86 W., is noteworthy because of its quaquaversal 

structure and because of the presence of several sills, 2 to 8 feet thick, 

within the sedimentary sequence. The sills and associated sedimentary beds form prominent ridges that nearly encircle the crest 

of the dome. A well drilled in 1949 on the dome penetrated igneous 

rock that may be a sill at a depth of 1,797 feet.

A relatively small dome is present in the valley of Trout Creek in 

the southeast part of T. 6 N., R. 86 W. The amount of its structural 

closure was not determined because the bedrock is concealed in the 

valley, and mapping was not extended farther east.

> Bass, N. W., Smith, H. M., and Christenson, H. E., op. clt.
170 CONTRIBUTIONS TO ECONOMIC GEOLOGY

The 'Twentymile Park syncline, in the southeastern part of the 

mapped area, contains in and near Twentymile Park a broad structural 

basin which has probably more than 600 feet of structural relief. 

The syncline extends southeastward from Twentymile Park, forming 

the dominant structural feature of the coalfield west of Oak Creek 

and Phippsburg.

The faults in Tps. 4 and 5 N., Rs. 86 and 87 W., are noteworthy 

because they have disturbed the. many thick coal beds there. They 

were mapped in the field by Campbell and were later somewhat modified by Bass. It is probable that only the more evident faults were 

observed and that coal mining in the area will reveal many more.

A steeply folded anticline on Sage Creek, chiefly in T. 5 N., R. 88 

W., and another on Fish Creek, in Tps. 4 and 5 N., R. 87 W., may 

coalesce southward to form the Williams Park anticline, whose crest 

is near the corner common to Tps. 3 and 4 N., Rs. 87 and 88 W. 

Little confidence can be placed in the designated positions of the 

structure contours in much of the west half of T. 4 N., R. 87 W., however, because the surface is formed on the Mancos shale, and few reliable structural data are available.

The Beaver Creek anticline is a large asymmetrical fold trending 

northwestward across the southwestern part of the area and for many 

miles beyond (Hancock, 1925, pi. 19, p. 33-34). The anticline, as 

shown on plate 19, merges at its southeastern end with the Pagoda 

dome. South of the country occupied by the Mesaverde group the

position of the structure contours on the north flank of the two anticlines is in most places tentative, because much of the bedrock in the 

area is concealed and only a few reliable structural data in the Mancos 

shale are available. For example, south-dipping beds in the Mancos 

shale exposed in a road cut along the South Fork road in sec. 17, T. 4 

N., R. 89 W., in the bed. of South Fork and in the west bank of the 

stream in the same vicinity, and south-dipping beds of sandstone in 

the north slope of the hill in the S# sec. 36, T. 5 N., R. 90 W., have 

been interpreted on .some structure contour maps as indicating a 

sharp northwest-trending anticline near Pagoda. On the present

map, Kowever, the attitude of these beds was interpreted as being the 

result of landslides in the Mancos shale and, therefore, not indicative

Of the true structure of the bedrock.

The Hart syncline, which lies southwest of the Beaver Creek anticline, is noteworthy because it accounts for the part of the Mesaverde 

group that contains the lower coal group and much of the middle coal 

group.

The Buck Peak anticline in T. 6 N., R. 90 W., appears to be the 

southeastward extension of the Breeze anticline of the Monument 

Butte quadrangle (Hancock, 1925, pi. 19; Sears, 1924, pi. 35). Most
GEOLOGY, MINERAL FUELS/ROUTT AND MOFFAT COUNTIES, COLO. 171

of the bedrock of the Buck Peak anticline is concealed; thus the position of the contours is tentative. The position of the northwesttrending fault that crosses the anticline is revealed by a fault scarp 

near the west margin of the mapped area. The fault is suggested on 

aerial photographs throughout its length and is shown on the geologic 

map (pi. 19). The amount of displacement shown along the fault is 

hypothetical.

Although the strata adjacent to the many dikes of the area are 

poorly exposed, the dikes appear to have disturbed the strata only 

slightly. An exception is the dike extending southwestward for a distance of 2 miles from Pilot Knob. It is only a few feet wide, but the 

beds on its southwest side are bent sharply upward against the dike 

wall; the beds on the northeast side, although poorly exposed, appear 

to be in their normal attitude but displaced downward a few feet relative to those on the southwest side. The data described in the 

section on metamorphism suggest that the thick sills have raised the 

overlying strata rather than assimilating the beds with which they 

came in contact.

COAL

Workable coal beds are present in the lies, Williams Fork, Lance, 

and Fort Union formations, but most of the coal mines have exploited 

beds in the lies and Williams Fork formations. The coal in these 

two formations has been divided into lower, middle, and upper groups 

by Fenneman and Gale (1906, p. 23-28). Stratigraphic sections of 

the coal beds are shown in plates 22-25.

LOWER COAL GROUP

The lower coal group includes all coal beds beginning about 400 

feet or slightly less above the base of the lies formation, as herein 

defined, and extending upward to the Trout Creek sandstone member. 

The coal beds in the lower part of the group are mined most extensively in the Oak Creek district. These beds thin northward and 

westward from the Oak Creek district, as shown in plate 20. Available 

data indicate that they probably do not extend with a continuous 

workable thickness as far north as Yampa River or far west of the Oak 

Creek district. Some lenticular coal beds at the position of the lower 

group are present in the Williams Fork Mountains, however, and a 

few miles west of the area herein described (Hancock, 1925, pi. 18). 

Coal beds in the upper part of the lower coal group are relatively thin 

in the Oak Creek district, but thicken and increase in number northward and westward. This coal has been mined extensively at Bear 

River and on Butcherknife Gulch north of Yampa River, and has been 

prospected from Butcherknife Gulch nearly to the north boundary of 

the area. At Bear River the top of the coal-bearing zone lies about 

400 feet below the top of the Trout Creek sandstone member.

345016 55 3
172 CONTRIBUTIONS TO ECONOMIC GEOLOGY

The three principal coal beds recognized by Fenneman and Gale 

(1906, p. 42) in the lower coal group at Oak Creek are known, in 

ascending order, as beds 1, 2, and 3 (Campbell, 1923, p. 38-39). The 

interval between beds 1 and 2 given by these authors is about 50 feet, 

and between beds 2 and 3, about 180 feet.

Mining in the Oak Creek district has shown that the coal beds of 

the lower group are irregular in thickness, and that the thickest beds 

split into two or more benches as they are followed underground by 

muiing operations. Therefore, nos. 1, 2, and 3, although referred to 

as beds, actually represent coal zones, each of which includes several 

coal beds. The intervals between the zones are about 150 and 200 

feet, respectively.

The main bed of no. 2 was mined in the Pinnacle mine of the VictorAmerican Fuel Co., where it is known as the Pinnacle bed. This bed 

was mined extensively in the Oak Hills mine (known also as mines 1 

and 2) of the Moffat Coal Co., where, throughout much of the mined 

area, it is split into two beds. The Moffat Coal Co.'s mine was 

originally opened on the no. 1 bed, and in the later years of its operation the no. 3 bed was mined simultaneously with the two benches of 

the no. 2 bed. The lower bench of no. 2 bed is mined at the Keystone 

mine, location 17, and was worked for many years at the Hayden 

mine, location 15. In 1940 and later years a bed that is assumed to 

be the no. 1 bed has been worked in the Hayden mine. Although it 

lies at a greater distance below the no. 2 bed than does the no. 1 bed 

at the Moffat Coal Co.'s Oak Hills mine, the general character of the 

coal and the presence of 1 foot or slightly more of dirty coal at the top 

of the bed at each place (McConnell, C. M., 1950, personal communication) suggest that the beds are equivalent.

Coal of the lower coal group has been worked by truck mines on Oak 

Creek southwest of the town of Oak Creek; on a high mesa 2 miles 

northwest of Phippsburg, where strip mining has been done; and on 

Trout Creek, in sec. 22, T. 4 N., R. 86 W. (the Apex mine, location

52), where a bed ranging from 4 feet to 4 feet 8 inches in. thickness, at

aboui the position of the no. 2 coal, has been mined.

A bed in the upper part of the lower group was mined from 1938 to

1940 by the late Casper Weberskirch at location 156 on Fish Creek 

near the center of the west line, NWK sec. 11, T. 4 N., R. 87 W., where 

it is 5 feet 6 inches thick and lies 90 feet below the top of a massive

white sandstone. Coal bed -A, 7 feet 7 inches thick, is worked at the

Sun mine, location 264 in Hayden Gulch in sec. 12, T. 4 N., R. 89 W.

This coal is about 600 feet below the top of the Trout Creek sandstone 

member, whereas the interval between the top of the Trout Creek

member and the no. 3 coal at Oak Creek is about 750 feet. The Rice 

mine in Hayden Gulch is in bed C, which is 9 feet 10 inches thick and 

130 feet stratigraphically above the coal worked at the Sun mine.
GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 173

The records of several old prospects in the Williams Fork Mountains 

west of Hayden Gulch indicate the presence of five workable coal beds 

in the lower coal group. These beds are designated A to E in ascending order (pi. 20, column 1A). However, the logs of core holes drilled 

in 1948 and 1949 reveal only a few thin beds in the lower group (see 

pi. 21), indicating that the beds are extremely lenticular.

MIDDLE COAL GROUP

The middle coal group includes the coal beds between the Trout 

Creek and Twentymile sandstone members. Throughout the eastern 

half of the area the principal coal beds of the group are, in ascending 

order, the Wolf Creek, Wadge, and Lennox. These beds occur in a 

sequence of rocks, about 400 feet thick, immediately above the Trout 

Creek sandstone member. Of the three coal beds, the Wadge is the 

most uniformly good in quality and workable thickness, and is mined 

most extensively. The Wolf Creek bed is irregular in thickness and 

generally contains thick lenses of bone and clay and a large amount 

of ash. The Lennox bed is only 3 to 4 feet thick in most places, but 

is 5 feet thick at the Edna strip mine near Oak Creek.

The two large mining operations at Mount Harris the Colorado 

and Utah Coal Co.'s Harris mine on the south side of Yampa River 

and the Vie tor-American Fuel Co.'s Wadge mine (pi. 17B), recently 

abandoned, on the north side of the river are in the Wadge bed, 

which is 8 to 9>2 feet thick. This bed derived its name from a rancher 

who opened a small mine in the bed on the south side of Yampa River 

opposite the present site of Mount Harris (Fenneman and Gale, 1906, 

p. 65). North of Mount Harris the principal beds of the middle coal 

group have been prospected in the central part of T. 7 N., R. 87 W., 

and on Cottonwood Creek in T. 8 N., R. 87 W., where the Wadge bed 

is more than 7 feet thick and the Wolf Creek bed is 13 to 15 feet 

thick. The Wadge bed on Grassy Creek and its tributaries south of 

Mount Harris is from 8% to 10 feet thick in several truck mines, and 

in the relatively large Grassy Creek mine at location 189 in sec. 34, 

T. 6 N., R. 87 W., which was developed and then shut down several 

years ago. The Wadge bed is about 8 feet thick in a strip mine that 

was opened recently south of McGregor. A coal bed 11 feet 9 inches 

thick that may be the Wadge or a bed 100 feet below it has been 

worked by a truck mine at location 160 in Fish Creek canyon in sec. 

34, T. 5 N., R. 87 W.

An upper bench of the Wolf Creek bed, 12 feet thick, has been 

worked at a truck mine, at location 46 on Middle Creek in the NE 

corner of the NWK sec. 10, T. 4 N., R. 86 W.

The Davis and Clark party of the Geological Survey mapped a 

total of 19 coal beds of the middle coal group in the Williams Fork 

Mountains in Rs. 88 to 90 W. Six or more of these beds, whose
174 CONTRIBUTIONS TO ECONOMIC GEOLOGY

thickness is greater than 5 feet, were also located by the Eby party 

in 1923 but were not correlated throughout the area. Most thick beds 

lie in the interval, about 400 feet thick, overlying the Trout Creek 

sandstone member. This coal-bearing sequence was penetrated in 

1948 and 1949 by core-drill holes of the Geological Survey hi Dunstan, 

Berry, Peck, and Jeffway Gulches. The data revealed by the cores, 

together with the data obtained from outcrops by the Davis and Clark 

and the Eby field parties, show the presence of three mam zones of 

coal beds in the sequence. These zones are herein designated F, 

G, and H (see pis. 20 and 21). Plate 21 shows 1 to 2 coal beds in 

zone F, 2 to 5 beds in zone G, and ID most places 2 thick beds in zone 

H. The core drilling revealed a thick coal bed between zones 6 and 

H in Dunstan and Jeffway Gulches. Coal bed I (pi. 20, column 1A), 

which is exposed at locations 387 and 385 near the west margin of the 

area, lies about 600 feet above the Trout Creek sandstone member. 

Coal bed J, 12 or more feet thick and a little more than 700 feet 

above the Trout Creek member, was worked many years ago at the 

Jim Dunn mine (location 275) hi the NW% sec. 18, T. 5 N., R. 89 W., 

and either the same bed or another bed 50 to 100 feet below it (called 

the Searcy Gulch bed) was exploited later in a truck mine at location 

388 in the SW% sec. 12, T. 5 N., R. 90 W. No data were obtained 

that indicate how far this bed, or these two beds, extend from the 

two localities. However, the hypothetical outcrop of a single bed 

at this horizon was sketched on the map (pi. 19) for a distance of 1

to 2 miles on each side of the two mines.

The data available suggest that the number of thick coal beds in 

the middle coal group increases westward in the Williams Fork 

Mountains. Moreover, on Yampa River, 7 miles west of the mapped

area, Hancock (1925, pi. 18) uncovered 12 coal beds in the middle

coal group, 8 of which are each, greater than 4 feet in thickness; the

total thickness of the 12 beds is 77 feet.

UPPER COAL GROUP

The upper coal group includes the coal beds of the Williams Fork 

formation that are in the sequence of rocks 650 feet thick, or slightly

less, immediately overlying the Twentymile sandstone member. A 

compiled section (pi. 20, column lA) of the coal beds of the upper

coal group that were prospected by the Davis and Clark and the Eby

field parties suggests the presence of 9 beds, herein designated beds 

K tO Sift ascending Order; however, detailed geologic work may reveal

that the number of beds actually present is fewer. Westward from 

Sage Creek, which is hi T. 6 N., R. 88 W., in the Williams Fork Mountains, the beds increase in number and thickness apparently to a point 

beyond the west boundary of the mapped area, for Hancock (1925, 

pi. 18) reported the presence of 16 coal beds in the upper coal group
GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 175

on Yampa River in Tps. 5 and 6 N., R. 91 W. However, thick coal 

beds of the upper group probably do not extend many miles east of 

Sage Creek.

A coal bed 3 feet or less in thickness crops out at many places along 

Fish Creek in the southeastern part of T. 5 N., R. 87 W. The Dry 

Creek bed, which is 10 feet thick and about 400 feet above the Twentymile sandstone member, is worked by several mines on Dry Creek in 

T. 5 N., R. 88 W.; and a 4X-foot bed, 240 feet below the Dry Creek 

bed, was formerly mined. Several other coal beds in the group are 

reported to have been prospected and penetrated by drill holes on 

Dry Creek many years ago, but they were not exposed at the time of 

the field investigation for this report.

Davis and Clark, in 1909, and Eby, in 1923 and 1924, uncovered at 

least 6 thick coal beds and at least 12 thin coal beds in the upper coal 

group, chiefly in T. 5 N., Rs. 89 and 90 W., in the Williams Fork 

Mountains. Most of the beds more than 5 feet thick are located from 

200 to 400 feet above the Twentymile sandstone member. At least 

one thick bed is present below this zone, and a few others are present 

above it.

COAL BEDS IN THE LANCE AND FORT UNION FORMATIONS

The coal in the Lance and Fort Union formations is of subbituminous rank and has a heating value, as mined, of about 9,700 Btu. 

Small wagon mines in the hills 1 to 2 miles north of Hayden were 

worked in the early twenties in the Lorella coal bed, a lenticular bed 3 

to 10 feet thick and about 50 feet above the base of the Lance formation. At about the same tune several small wagon mines, two of 

which were in sec. 33, T. 7 N., R. 90 W., north of U. S. 40, were worked 

in the Kimberley bed in the lower one-third of the formation. The 

abandoned White mine, worked in 1923, and two prospect tunnels 

driven in 1946 at location 334 in the NE% sec. 4, T. 6 N., R. 89 W., 

are probably in the Kimberley bed.

Two beds of coal of subbituminous rank, separated by 30 to 45 feet 

of shale, are present about 375 feet above the base of the Fort Union 

formation in sees. 25 and 26, T. 7 N., R. 90 W., and sec. 30, T. 7 N., 

R. 89 W., a short distance north of U. S. 40; each bed ranges from 4 

to 6 feet in thickness. A coal bed about 17 feet thick, 250 feet below 

the top of the Fort Union formation, is exposed at many places, and 

has been worked by several truck mines on Dry Fork of Little Bear 

Creek in the western part of T. 8 N., R. 89 W.

QUALITY

Analyses of representative samples from the three groups of coal 

in the lies and Williams Fork formations, and of somewhat less reliable 

coal samples from the Lance and Fort Union formations, are shown in 

table 1. The reliability of the samples from the Lance and Fort Union
176 ' CONTRIBUTIONS TO ECONOMIC GEOLOGY

formations, which were obtained from wagon and truck mines, is 

uncertain because some of the samples were taken under thin overburden from beds that may have been somewhat weathered. Table 2 

shows averages of several analyses of coal from the lower, middle, and 

upper coal groups, and from the Lance and Fort Union formations. 

These analyses show that the moisture content increases and the 

heating value decreases from older to younger coal.

All of the coal is noncoking. As was pointed out by Campbell 

(1923, p. 68), the coal of the lies and Williams Fork formations of this 

region is hard and shiny, breaks in large lumps and blocks when 

mined, withstands transportation to distant markets, and is clean to 

handle. Coal of the lower and middle groups is of bituminous rank. 

Coal of the upper group contains slightly more moisture and less 

volatile matter and has a lower heating value than coal of the middle 

and lower groups; it is on the margin between subbituminous and 

bituminous rank, but is here classed as subbituminous. Coal in the 

Lance and Fort Union formations contains considerably more moisture 

than the older coal, and so is not suitable for shipping long distances. 

It is of subbituminous rank, has a shiny luster, and is mined without 

much slack.

RESERVES

Slightly more than 9 billion tons of coal is present in the mapped

area at depths of less than 3,000 feet, according to calculations of coal 

reserves made by Frank D. Spencer for this report. About 82 percent 

of this total reserve is coal of bituminous rank and 18 percent is coal 

of subbituminous rank. Slightly less than 100 million tons has been 

mined or lost in mining. The calculations were necessarily based on 

data obtained from natural exposures of coal beds, from measurements 

in the few mines and prospects in the area, and from core-drill records

in a few relatively small tracts. Undoubtedly, much more coal than 

the 9 billion tons disclosed by these methods is present. For example,

data revealed by core drilling by the Geological Survey in the Williams

Fork Mountains in 1948 and 1949 revealed the presence of much more 

coal in the middle coal group of the Williams Fork formation than was 

known before.

Moreover, although no coal beds lying at depths greater than 3,000

feet have been included in the calculations, geologic information on the

region including the mapped area indicates that much coal is present

below that depth, principally in the northwestern third of the mapped

area.

Tiie ooal reserves reported in. tatoles 3 9 are categorized, toy raiiltj

reliability of data used to calculate reserves, thickness of beds, and 

thickness of overburden. Reserves in these categories are reported by 

individual coal beds and by townships. Summaries by township and 

county, and the grand totals for the mapped area, are shown in table 9.
GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 177

The coal ranks reported are bituminous and subbituminous. Coal of 

anthracite rank has not been differentiated in the tables because it 

occurs only in local areas near intrusions and the reserves are relatively 

small (however, some of the deposits might be large enough to warrant 

development of the anthracite as special fuels). Coal of the lower and 

middle coal groups of the lies and Williams Fork formations is of 

bituminous rank. Coal of the upper coal group of the Williams Fork 

formation is on the borderline between bituminous and subbituminous 

ranks. Analyses of some samples from the upper coal group (table 1) 

indicate bituminous rank, and analyses of other samples indicate subbituminous rank; for simplicity, all coal in the upper coal group is 

classed as subbituminous. Coal in the Lance and Fort Union formations is subbituminous.

In calculating the coal reserves in the areas containing coal of bituminous rank, lines were drawn on a copy of the geologic map (pi. 19) 

through points where the coal beds are 14, 28, and 42 inches thick. 

These lines form boundaries of areas within which the coal is assumed 

to be 14 to 28 inches, 28 to 42 inches, and more than 42 inches thick. 

In calculating reserves in the areas containing subbituminous coal, 

lines were drawn on the geologic map through points where the coal 

beds are 2.5, 5, and 10 feet thick. These lines are assumed to form 

boundaries of areas within which the coal is from 2.5 to 5 feet, 5 to 10 

feet, and more than 10 feet thick. These thickness categories correspond with those recommended by the National Bituminous Coal 

Advisory Council for reporting coal reserves.

The reliability of data used to calculate reserves is indicated as 

follows: coal within 2 miles of an outcrop, a prospect or mine opening, 

or a drill hole is classed as measured and indicated, undifferentiated; 

and coal lying not more than 2 miles outside the areas containing 

measured and indicated coal is classed as inferred.

Data supplied by mining, core drilling, and prospecting indicate 

that certain coal beds in the middle and upper coal groups of the 

Williams Fork formation are persistent for at least 2 miles. Therefore, an estimate of inferred coal was made for tlrese beds. On the 

other hand, the coal beds in the lower coal group of the lies formation 

are known from mining operations, prospecting, and core drilling to 

be lenticular; and coal beds in the Lance and Fort Union formations 

are known from observations on the outcrops and prospects to be 

lenticular. Consequently, no inferred reserve was calculated for this 

coal even though it is probable that coal beds having classifiable 

thickness are present outside of the areas shown to contain measured 

and indicated, undifferentiated, coal.

Information on the amount of overburden was obtained from the 

geologic map by using the structure contours in conjunction with the 

topographic contours. Reserves have been reported in the following
178 CONTRIBUTIONS TO ECONOMIC GEOLOGY

overburden categories: less than 1,000 feet, between 1,000 and 2,000 

feet, and between 2,000 and 3,000 feet. Estimates of coal reserves 

at shallow depths, which would be of possible interest to strip miners, 

were not prepared owing to lack of data.

OIL AND GAS

The Tow Creek, north Tow Creek, and Oak Creek oil pools, and 

the Pagoda and Williams Park gas pools are within the mapped area. 

The Tow Creek oilfield was discovered in 1924. Its total yield to 

January 1, 1952, was 2,151,174 barrels of oil (Goodin and others, 1952 

p. 91). The oilfield contains the Tow Creek and north Tow Creek 

pools near the crest of the large asymmetrical Tow Creek anticline. 

The two pools, about 1% miles apart, are separated by an area that 

has yielded no producing oil wells. All wells in the north pool were 

abandoned several years ago. Most producing wells in the pools are 

a short distance east of the axis of the anticline.

The available evidence indicates that the oil is present in fracture 

zones in limy shale, shaly limestone, and limestone beds of Niobrara 

age. Gas shows are common in a unit about 300 feet thick that constitutes the uppermost beds of Niobrara age, and most of the oil is 

present in the next underlying 500 feet of beds; a few wells have 

produced oil from the lowermost 300 feet of the Niobrara. The 

entire sequence of oil- and gas-bearing beds is devoid of water. About

hftlf Of the 40 Wells failed to produce oil. Moreover, many of tke dry

noies are disiriWad" irregularly among the oil-producing wells, and 

some wells that are situated 400 to 500 feet from oii-ProduoinS w©lls 

appear to have tapped the same fracture zone as the producers, for 

the yield of the old wells declined abruptly when the new wells began

producing.

Ten or more wells on the Tow Creek anticline tested the Frontier 

sandstone, which yielded water, and five of these reached the Dakota 

sandstone, which yielded hot water. The Texas Co.'s Belle Dennis

no. 4 in the SE^NE^SEX sec. 7, T. 6 N., R. 86 W., near the crest of 

the anticline, reached basement rocks at a depth of 5,307 feet. This 

well penetrated beds of sandstone at depths of 4,000 to 4,135 feet, 

which yielded hot water, and beds of sandy limestone and red rock 

that may be equivalent to the uppermost beds of the Sundance formation at depths of 4,303 and 4,313 feet, which yielded shows of oil 

and gas. Below 4,313 feet, the drill penetrated 60 feet of sandstone 

and conglomerate, 70 feet of brown sandstone and sandy limestone, 

60 feet of gray sandy limestone, 480 feet of red rock containing thin 

beds of limestone, and 407 feet of shale, sandy shale, and thin beds of 

conglomerate reported to contain fossils of lower Pennsylvanian (Des 

Moines) age. The basal 57 feet of the lowest unit is sandy shale and
GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 179

rests on gneiss. A second well drilled in 1949 in the

sec. 7, T. 6 N., R. 86 W., to a depth of 5,627 feet, reached pre-Cambrian

rocks.

Oil that seeps from beds in the upper part of the Mancos shale east 

of Tow Creek in the SE^NWK sec. 32, T. 7 N., R. 86 W., was used as 

a lubricant by local ranchers and coal miners 40 to 50 years ago 

(Fenneman and Gale, 1906, p. 79). In 1919, oil-saturated sandstone 

and sandy shale in the upper part of the Mancos shale was mined on 

Tow Creek in the WK sec. 32, T. 7 N., R. 86 W., and heated in small 

retorts (Crawford, Willson, and Perini, 1920, p. 47-48) in a commercial effort to extract oil from the shale.

In 1942, a well was drilled to a depth of 3,250 feet on the Wolf 

Creek dome in the SE^SW/4 sec. 18, T. 7 N., R. 86 W. Most of the 

rock that was penetrated was calcareous shale of the Mancos shale, 

and the well bottomed in igneous rock. An 80-foot thickness of 

igneous rock between depths of 2,060 and 2,140 feet suggests that the 

igneous rock at the total depth may represent a sill rather than the 

main mass of Sand Mountain.

Five wells have been drilled on the Chimney Creek dome in the 

NW/4 sec. 4, T. 7 N., R. 86 W. The first weU, drilled in 1920 by the 

Plateau Oil Co., reached a depth of 1,360 feet, 10 feet below the top 

of the Morrison formation. Gas was present at several depths, and 

some of the sands, including the Dakota sandstone, yielded water. 

Two dry holes near the first well were drilled in 1927 and 1928 by the 

Elk Head Development Co. to depths of 900 and 1,200 feet. In 

1929, the Midwest Refining Co. drilled a well in the same locality to a 

depth of 1,735 feet. It penetrated 55 feet into the Entrada sandstone, which yielded water that rose 1,320 feet in the hole. A well 

was drilled in 1949 in the NWtfNEftNWtf sec. 4, T. 7 N., R. 86 W., 

to a depth of 2,078 feet, penetrating igneous rock, possibly a sill, at a 

depth of 1,797 feet, below 77 feet of Triassic redbeds.

In about 1920, two gas wells were drilled in the Williams Park gas 

pool on the crest of the Williams Park anticline in T. 4 N., Rs. 87 and 

88 W., near the south margin of the area; one is capped and the 

other is abandoned. The first test hole on the anticline was drilled 

in 1919 and 1920 by the Twentymile Oil and Gas Co. in the SW corner of the NWtfSEtfSWM sec. 30, T. 4 N., R. 87 W. It is reported 

that a show of oil was obtained in the Frontier sandstone at a depth 

of 1,310 feet, and that water, oil, and gas were yielded by the Dakota 

sandstone between depths of 1,710 and 1,725 feet, the total depth. 

Well no. 2 of the Twentymile Oil and Gas Co., drilled in 1919 in the 

SE^SE^ sec. 36, T. 4 N., R. 88 W., is reported to have obtained 

several million cubic feet of gas per day from the Dakota sandstone 

between depths of 320 and 453 feet; the well is capped. Well no. 3, 

drilled in 1919 and 1920 in the SWtfNWtfNWtfSWtf sec. 31, T. 4 N:.
180 CONTRIBUTIONS TO ECONOMIC GEOLOGY

R. 87 W., is reported to have yielded initially 10 million cubic feet 

of gas per day from the Dakota sandstone between depths of 350 

and 530 feet, the total depth, and to have been plugged.

Well no. 4 was drilled in 1920 by the Producers and Refiners Corp. 

in the center of the north line of the SJSNEtfSEtf sec. 36, T. 4 N., R, 

88 W. It is reported that water and a show of oil were obtained at a 

depth of 85 feet in the Frontier sandstone; gas at 525 and 580 feet 

in the Dakota sandstone, and at 990 feet; gas and hot water at 1,085 

feet in sandstone that may be the Entrada sandstone, and gas in the 

same sandstone at 1,125 feet. The driller's log suggests that the 

well penetrated, in descending order, the lowermost few hundred

feet of the Mancos shale and the Dakota sandstone, Morrison formation, Curtis formation, Entrada sandstone (between 1,050 and 1,140 

feet), and 420 feet of redbeds (to a depth of 1,159 feet), possibly of 

Triassic age, much of which may be equivalent to the Chinle formation. The bottom few feet of the hole is reported on the driller's 

log to be in reddish-gray granite, but considerable doubt exists that 

granite was penetrated. Drill cuttings from a depth of 1,516 feet, 

which is only 43 feet less than the total depth of the hole, contained 

red arkose according to F. F. Hintze (written communication, about 

1945) who examined the cuttings while the wall was being drilled.

The discovery well in the Oak Creek pool in sec. 2, T. 3 N., R. 

86 W. was completed in 1949 and is reported to have yielded 250 

barrels of oil a day from the Shinarump conglomerate. The well was 

drilled to a depth of 6,747 feet and penetrated the upper part of the 

Moenkopi formation of Triassic age. Following this, two dry holes

 were drilled in sec. 2, one to a deptla of 6,856 feet and. the Other tO a

depth of 7,135 feet.

Two gas wells were completed in 1948 and 1949 in sec. 34, T. 4 N., 

R. 89 W., on the Pogoda dome. Both yielded gas from the Shinarump conglomerate of Jurassic age, which was penetrated at a depth 

of about 3,900 feet. The first well was drilled to a total depth of

4,900 feet and penetrated the Weber sandstone and the uppermost 

beds of the Morgan formation of the Pennsylvanian system. This 

weU is reported to have yielded 7,700,000 cubic feet of gas per day;

and the second well, 1,930,000 cubic feet of gas per day. Botk wells

are shut in.

Three test wells have been drilled in the SW% sec. 32, T. 4 N., 

R. 89 W., on the Beaver Creek anticline. The first well was drilled in 

1924 and reached the upper part of the Morrison formation; it yielded

 water in tk© Frontier and Dakota sandstones. The second -well

was drilled in 1943 and penetrated the top few feet of a redbed unit

that is probably the Chinle formation. Many cores obtained in the

basal 1,000 feet of the hole showed that the beds were dipping at a 

high angle. The third well was drilled in 1946 at the northeast corner
GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 181

of the SWK sec. 32, a little more than a quarter of a mile north and 

northeast of the first two holes and, therefore, higher on the crest of 

the anticline. The well reached a total depth of 5,801 feet and is 

reported to have penetrated the uppermost 552 feet of the Pennsylvanian system, the uppermost 120 feet of the Pennsylvanian rocks 

being identified by some geologists as the Weber sandstone.

A dry hole was completed in 1950 in sec. 24, T. 4 N., R. 90 W., on 

the Beaver Creek anticline. It was abandoned at a depth of 5,853 feet 

after penetrating the Dakota sandstone, Entrada sandstone, Shinarump 

conglomerate, and the Weber sandstone, all of which yield oil and 

gas in some places in northwestern Colorado.

Analyses of the gas from the Tow Creek and Williams Park gasfields are shown in table 10, and analyses of the crude oil from the Tow 

Creek and Oak Creek fields are shown in table 11. Analyses of the 

gas from the Niobrara shale of the Tow Creek field show a heating 

value that ranges from 1,047 to 1,264 Btu per cubic foot, which is high, 

and show large variations in amounts of carbon dioxide, methane, and 

ethane, which possibly are due to local metamorphic effects of igneous 

intrusions. Analyses of gas from the Dakota sandstone of the Williams 

Park field show a lower heating value 794 Btu per cubic foot; the 

principal constituents are methane and nitrogen, but about 1 percent 

helium is also contained.

Analyses of crude oil from the Niobrara shale of the north and south 

Tow Creek pools (see p. 168, 169, and table 11) show a considerable 

difference in composition of oil from the two pools, possibly due ,to 

local metamorphic effects of igneous intrusions.

The Buck Peak anticline in T. 6 N., R. 90 W. is an eastern extension 

of the Breeze anticline of the Monument Butte quadrangle (Hancock, 

1925, pi. 19). Little confidence can be placed in the position of the 

structure contours showing the Buck Peak ancicline, because the bedrock is concealed in most of the area. No test well has been drilled 

on the anticline. The data on plate 19 indicate that if a test well were 

drilled near the east quarter corner of sec. 26, T. 6 N., R. 90 W., it 

should penetrate the Dakota sandstone at a depth of about 7,900 feet.

LITERATURE CITED

American Association of Petroleum Geologists, 1944, Tectonic map of the United

States. 

Anderson, C. C., and Hinson, H. H., 1951, Helium-bearing natural gases of the

United States: U. S. Bur. Mines Bull. 486, 141 p. 

Campbell, M. R., 1923, The Twentymile Park district of the Yampa coal field,

Routt County, Colo.: U. S. Geol. Survey Bull. 748, 82 p. 

Chisholm, F. F., 1887, The Elk Head anthracite coal field of Routt County, Colo.:

Colo. Sci. Soc. Proc. 2, p. 147-149. 

Colorado State Planning Commission, 1951, Year Book of the State of Colorado,

1948-1950. 680 p.
182 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Crawford, R. D., Willson, K. M., and Perini, V. C., 1920, Some anticlines of Routt

J*"? County, Colo.: Colorado Geol. Survey Bull. 23, 59 p.

Eby, J. B., 1925, Contact metamorphism of some Colorado coals: Am. Inst. Min.

and Met. Eng. Trans., v. 71, p. 250. 

Emmons, S. F., 1877, Valleys of the upper Yampa and Little Snake Rivers, in

Hague, Arnold, and Emmons, S. F., U. S. geological exploration of the

fortieth parallel (King): Prof, papers, Eng. Dept., U. S. Army, no. 18, v. 2,

p. 184-187. 

Fenneman, N. M., and Gale, H. S., 1906, The Yampa coal field, Routt County,

Colo.: U. S. Geol. Survey Bull. 297, 96 p. 

Gate, H. S., 1910, Coal fields of northwestern Colorado and northeastern Utah:

U. S. Geol. Survey Bull. 415, 265 p.

Goodin, George, and others, 1952, Resume, Rocky Mountain oil and gas operations for 1951: Petroleum Information, Inc., Denver, Colo. 

Hancock, E. T., 1925, Geology and coal resources of the Axial and Monument

Butte quadrangles, Moffat County, Colo.: U. S. Geol. Survey Bull. 757, 134p. 

Hewett, G. C., 1889, The northwestern Colorado coal region: Am. Inst. Min. Eng.

Trans., v. 17, p. 375-380. 

Hills, R. C., 1893, Coal fields of Colorado: U. S. Geol. Survey, Min. Res. 1892,

p. 319-365. 

McFarlane, G. C., 1929, Igneous metamorphism of coal beds: Econ. Geology, v.

24, no. 1, p. 1-14. 

Parsons, H. F., and Liddell, C. A., 1903, Coal and mineral resources of Routt

County: Colo. School of Mines Bull. 1, no. 4, p. 47-59. 

Sears, J. D., 1924, Geology and oil and gas prospects of part of Moffat County,

Colorado, and southern Sweetwater County, Wyoming: U. S. Geol. Survey

Bull. 751, p. 269-319, pi. 35. 

Storrs, L. S., 1902, The Rocky Mountain coal field: U. S. Geol. Survey Ann.

Rept. 22, pt. 3, p. 415-471. 

Weston, W., 1904?, The hydrocarbon field of western Colorado arid eastern Utah.

on the projected line of the Denver, Northwestern and Pacific Railroad: 39

p., map, Denver, Nortliwestern arid Facific Railroad.

 1909, The Yampa coal field of Routt County, Colorado, on the projected 

line of the Denver, Northwestern and Pacific Railroad (Moffat road): 62 p., 

map, Denver, Northwestern and Pacific Railroad.

1914, The Yampa coal field of Routt County, Colorado, on the line and

the extension as projected of the Denver and Salt Lake Railroad (Moffat 

road): 62 p., Denver and Salt Lake Railroad.

White, C. A., 1878, Report On the geology Of a portion of northwestern Colorado:

U. S. Geol. and Geog. Survey of the Territories, 10th Ann. Rept. for 1876,

j>- 3 eo, pi. 2.

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and adjacent parts of Utah and Wyoming: U. S, Geol, Survey 9th Ann.

Rept., p. 683-712, pi. 18.
TABLES 1-11
184 CONTRIBUTIONS TO ECONOMIC GEOLOGY

-a 

I

. Q 

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ssoiam^p-flv

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o 

o

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location inmine

0 £J cQ

Mine allocation

§338

IN CO to

rococo

CMOOOOO

3C588

,_.lOt^lN

co 5 "3!

to IN

oo to

oooo oooo c

to CN O O CM ** CO ^J* O 

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; |

i i

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ssss ^sss ^

(NT)lto T)<COO O

COCOCO COCOb- *

INrHrtrt COO»CO'5t< CO

"SSlo S^SS "

cooococn o-*Tf<co oo

gSSS5 g§^'^ gg

2£ i i 55 i »

S2SS E;§SSS

22rtd £233

222S 2J5S

SEgSS S^;§g

to to to IO to to to to 1

S^S ql^^^ 3§K t^ooooa

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SSB

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««OP ^OP ««OP ««OP ««OP ^«OP ««OQ'«Ofi

CO

g

CO

i

p

lower No.2, coal 

group.

south IFaceif entry... _

a

ro co w

to co N

CO N id

1-1 IN CO « O> rH

c e c

c c c

e c

1

c 1** 

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g . !

lip i

s g£« ! 

 5 «Jtf r i 3 Od/ i

art OH i

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20055 4

«

group.

No. lower 2, coal 

group.

Mali slope- _..._..

S ' 2 *"

i ^ 5fiJ ! . . 93* 1 js ia.^ ! as «o^

i 1^ 111 S^oo m?^> 

, a - W fflt>

o %£* "33 ^S

(3 S t «dg . 20^; 3al«

0 S

 «o

c c

c

41 Avsrageof samples. car .

22

Pinn_scle nieVlcto- ofSEK ArtiericanFuelCo., 861. T.INT.. seo.36 R.
Binnacle no. 1, SE ji sec. 

36, T. 4 N., R. 86 W.

DODODoDo.

Pinnacle no. 2, SEJi sec. 

36, T. 4 N., R. 86 W.

Keystone mine, Keystone 

Coal Co., SEJ4 sec. 19, 

T. 4 N., R. 85 W.

DODODO..

78

78

78

78

78

78

78

17

17

17

17

Face of no. 3 south entry, 

top split.

Face of no. 5 south centry> 

bottom split.

Face of no. 4 room, A 

slope, back entry.

Face of no.-24 room, A 

H slope, back entry.

Composite of lab. nos. 

A13684-A13687.

No. 1 room, A slope, back

entryFace of no. 5 room, D

slope, back entry.

No. 4 north entry, 350 ft 

ofl no. 2 dip entry.

No. 2 dip entry, 150 ft in 

by no. 6 north entry.

No. 5 north entry, 150 ft off 

no. 2 dip entry.

Composite of lab. nos. 

B13141-B13143.

. do. 

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

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

.....do.. ...

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

.....do ... ..

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

.....do ... 

..... do . 

 ..do .. 

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

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

..... do... 

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

..... do-... .

.. do .. ..

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

.. do . ..

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

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

 .do 

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

A13684

A13685 

A13686

A13687

A13688

A34979

A13683

B13141 

B13142 

B13143

2.9

3.4

3.1

3.0

3.4

4.0

3.9

4.1

4.0
186 CONTRIBUTIONS TO ECONOMIC GEOLOGY

tD

US 3 "3

Ultimate

Proximate

mg

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17 > 6 >

Left facenorth riba1no. ft 30°W.4,500 N. entry, 

of shat.

Face ofstrip pit,ft 480ft south of1,670 west, 

24. center sec.sam'nlfi Tii-^-nlA 

,-H r~ i^ IO IT

CN i-H lO

lO CO O5 

T}< CN Oi 

CO O CD 

 ^ CO N 

CO Is- ^H

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fl

ILennox, middle 

coal group.

Tipple samptons) (45...

03 ! -

"0£ 1^> "HJ?

rj 00 COQ" 1

§ w-"1 r o o 

cjW w -oOTii

W W

|. f 0

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 ** : o ^ 

 £ . .£ S

' &% 1 ' bi <» o n H 52

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. B 2 3

°s : . & -.&^

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go^ -S,.; H'O|^

<) K-s S

IO

8CO 

OJ

C C

CT

ft heading, 100 inMain 

entry.

«

i

O

O
Flame Coal Co., SEJ4 

sec. 12, T. 3 N,, R. 86 W.

Do 

Do------ ----- ...

Middle Creek mine of 

Frank Oould, NWJ4 sec. 

10, T. 4 N,, .R. 86 W.

'Do - .,.. ...

T. 4 N., R. 86 W.

of drift 54 ft from portal, 

NEJ4 sec. 32, T. 5 N., R. 

86 W.. . ....

Greenhalgh shaft, NE}<

sec. 32, T. 5 N., R. 86 W.

southeast of Milner, SEJ£ 

sec. 12, T. 5 N., R. 86 W.

Chergo, 6 miles southeast 

of Milner, NWJtfNEJi 

sec. 13, T. 5jN., R. 86 W.

42

42

42

46 

46

52

99a

99b

89

90

entry, 1,200 ft from

main entry, 1,200 ft from 

mouth.

B17623 and B17624.

Face of main entry, 390 ft 

from portal.

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

portal; 25 ft in by room 

no. 6. .

- do ........

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

. .do ..... ...

Wolf Creek, upper bench, 

middle coal 

group.

Wolf Creek, lower bench, middle coal group.

coal group.

.. do... -.-.

coal group. 

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

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

.-...do ---

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

Williams Fork... 

-.--do .... ..

lies-----..... 

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

 do 

 ..do ... 

B 17623

B 17624

C58119 

C58120

B34464

C73282

E74290

1832

31038

2.5

3.5

5.6

5.0

6.2

4.0
TABLE i. Analyses of coal samples from parts of Routt and Moffa

Mine and location

Mine of Z. McCrosfcy, 1 

mile westofMilner.SEJi 

SWJ< sec. 9, T. 6K, E. 

86 W.

Do.. _... 

Mine no. 1 of CurtisCoal 

Co., 2 miles south ol Milner, sec. 22, T. 6 &,. B. 

86 W.

Mine of Elk Creek Wining 

Co. , 3 miles south of Milner, SE^sec. 21, -1.6 N., 

R. 86 W.

Do . _-... 

Do . ----.- .-

Mine no. 1 of McNeil Coal 

Co. at McGregor,SEK 

sec. 16, T. 6 IsT., E86W.

Mine no. 3 of McNdl Coal 

Co. at McQregoi, SE# 

sec. 16, T. 6 NT., E86 W.

No. 

on 

map

116 

116

136 

129 

129 

129 

122 

123

Location in mine

Face of main entry, 270 ft 

from mine mouth.

1 ,000 ft northwest of mine 

mouth, upper bench.

1 ,000 ft northwest of mine 

mouth, lower bench.

Composite of Lab. nos. 

32971 and 32972.

Working face, 1 ,600 ft south 

of mine mouth.

Pace of main entry, 385 ft 

from mine mouth.

Coal bed and 

group

Wolf Creek, middle coal group.

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

Brooks, lower 

coal group.

Wolf Creek middle, coal group.

.... .do.... ..... ._

.... .do.. ...

..... do. ... .

Wadge, middle 

coal group.

Formation

Williams Fork... 

.-...do .

lies.... _

Williams Fork... 

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

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

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

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

o

a

i

1843 

1991 

22750 

32971 

32972 

32973 

32974 

32975

Air-drying loss

4.4 

3.4 

2.8 

3.4 

3.4 

3.4 

3.0 

4.3
Tow Creek mine of Tow 

Creek Coal Co., 1 mile 

west of Milner, NEJi sec. 

17, T. 6 N., R. 86 W.

Mine of Schmidt brothers, 

\\i miles northwest of 

McGregor, SEJiNEJi 

sec. 8, T. 6 N., R. 86 W.

Amos McCroskey mine, 2 

miles north of McGregor, 

NWJi sec. 4, T. 6 N., R. 

86 W.

Do.

Do.

Rice mine, 2 miles northeast of Bear River, 

NWJi sec. 1, T. 6 N., R. 

87 W.

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

Old Butcher Knife mine, 2 

miles northeast of Bear 

River, NW>i sec. 1, T. 6 

N., R. 87 W.

No 1 mine of Bear River 

Coal Co., Bear River, 

SWJi sec. 11, T. 6 N., M. 

87W.

Do 

Do.

124

117a

113

113

114

163

163

164

170

170

170

Main entry, ISO ft from

mouth.

Face of main entry, 15 ft 

north of rock tunnel.

Southeast wall, 125 ft 

northeast of mine 

mouth.

Right rib, no. 4 room, 170 

ft off main entry.

Face of main entry, 240 ft 

from mine mouth.

Old face, 300 ft southwest 

of mine mouth (old 

mine).

Face of main entry, 155 ft 

from mine mouth.

200 ft southwest of mine 

mouth.

375 ft west of mine mouth.

Face of A panel, no. 4 

south entry.

Face of no. 4 north entry.

group.

er coal group, 

 do 

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

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

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

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

.... .do ... ..

lower coal 

group.

..... do.. 

.... .do... ..

lies...... .......

..... do ..

.....do 

..... do. ..

..... do .....

 do... 

 do ..... .

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

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

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

. .do... 

B57508

A2698

A3336

A72343

A4949

A2394

A42971

A2395

22724

A2187

A2188

6.0

5.0

7.4

1.7

6.6

3.3

5.1
TA.BIE 1. Analyses of coal samples from -parts of Routt and Moffa

Mine and location

No. 1 mine of Bear River 

Coal Co., Bear River, 

SWi,i sec. 11, T.6 N., M. 

87 W.

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

: Do ........... ........

Do _....----.- -.....

Do......--..- .--.....

Do.....--_... --.......

Abandoned mine, J-2 mile 

sou "tli of Bear River, on 

soutl bank of Tampa 

River, sec. 14, T. 6 N., 

R. 87 W.

ISTo. 

on 

maj

170 

170 

liO

1/0 

170

170

17O

172

Location in mine

60 it from £> panel, no. 4 

north entry.

N o.l room, F panel, no. 2 

opening.

Composite of lab. nos. 

4J187-A2190.

Fare of drift entry, 750 ft 

oJ main slope.

Room no. 1 off upper ^4 

ffltry, 1,000 ft from slope 

mouth.

130(t south of main prospect slope and 1,500 ft 

from mouth.

Composite of lab. nos. 

I13146-B 13148.

Eate of drift, 100 ft from

opening.

Coal bed and 

group

Bear River, 

lower coal 

group.

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

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

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

.....do --.,...

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

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

.....do.. _ ......

Formation

lies-. -----

 do 

... -do ------

 -do .----..

 do --...

-.-do ......

-..-do ....-.

- do -----

o

a

JO

a

A2189 

A2190 

A2191

B 13146 

B 13147

B 13148

A2483

Air-drying loss

4.5 

4.9 

5.0

4.6 

5.0

4.8

4.8 

4.6
Alien prospect, J£ mile 

south of Bear River, sec. 

14, T. 6 N., R. 87 W.

Alien or Hawkeye prospect, 1 mile south of 

Bear River, sec. 23, T. 

6 N., R. 87 W.

Indian Creek mine of 

Routt Pinnacle Coal Co., 

at Coalview, NE34 sec. 

23, T. 6 N., R. 87 W.

Do 

171a 

173 

182 

182

300 ft from mine mouth ...

500 ft from mine mouth. . . 

Face of no. 5 room, B slopeFace of no. 4 room, B 

raise.

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

Bear River (?), 

lower coal 

group.

Lower coal 

group.

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

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

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

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

 .do ..

A2480 

A2481 

32, 987 

A2482

7.

3. 

3.

5.

Mount Harris district

Harris mine of Colorado 

and Utah Coal Co., Mt. 

Harris, SW^SWJi sec. 

15, T. 6 N., R. 87 W.

Do... ..._.__ 

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

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

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

Do ... 

177 

177 

177 

177 

177 

177

Main entry, 2,600 ft south 

of mine mouth.

Main dip entry, 1,700 ft 

southwest of mine 

mouth.

Hill entry, 800 ft southeast 

of mine mouth.

Composite of lab. nos. 

22737-22739.

Face of U raise, 2,500 ft 

above main south entry, 

8,000 ft south of mine 

mouth.

Left rib, 20 ft from no. 10 

south entry.

Wadge, middle 

coal group.

 do ..

 ..do ..

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

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

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

Williams Fork... 

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

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

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

. .do.. ......

 do ... _-

22737 

22738 

22739 

22740 

C26467 

31199

2.

2.

2.

2.

2.0 

5.
TABLE 1. Analyses of coal samples from parts of Routt and Moff

Mine and location

No. 

on 

map

Location in mine

Coal bed and 

group

Formation o 

d

x> 

a 

i-l

r-drylos

*

Mount Harris district Continued

Harris wine of Colorado 

and "Utah Coal Co.,Mt. 

Harris SWKSW>4 sec. 

15T.6N., E.87 Vf

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

Do . -_.... .

Bo... _...._ ...... _...

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

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

177 

177 

177

177 

177

177

177 

177

No. 3 east entry, main 

south slope.

0 slope, left rib, main 

south entry.

Face of no. 7 east back 

entry, no. 2 south entry.

No. 1C east entry, main 

south entry.

Left rib, last crosscut in A 

slope.

Left rib, main soutb entry. 

Rib ofmaindipemtry.....

Composite of lab. nos. 

31199-31206.

Wadge, middle 

coal group.

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

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

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

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

. -do.-... -. 

 - do.. 

 .-do-- .

Williams Fork-.

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

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

..... do ___ 

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

.. do ...... 

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

31200 

31201 

31202

31203 

31204 

31205

31206 

31207

7

5

6

5

5

6

5

5
Do... ..................

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

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

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

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

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

Co.'s prospect mine, 

Sec. 15, T. 6 N., R. 87 W.

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

Do.-.... ...........

177

177

177

177

177

177

177

177

177

entry.

A2179-A2182.

bench.

bench.

A2184 and A2185.

 do.. 

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

 do - 

... ..do 

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

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

Wolf Creek,

middle coal 

group.

.....do. . .

.....do .

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

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

 do 

 ..do --..

 do .. .

 do -....

Hes-. __

 do 

 do ..

A2179

A2180

A2181

A2182

A2183

A72339

A2184

A2185

A2186

4.9

5.1

5.3

3.7

5.3

4.5
TABLE 1. Analyses of coal samples from parts of Routt and Moffa

Mine and location

No. 

on 

map

Location in mine

Coal bed and 

group

Formation o

a

X!

C3

Air-drying loss

Mount Harris district Continued 

No. 1 Wadge mine of Victor-American Fuel Co., 

Mt. Harris, sec. 15, T. 

6 N., R. 87 W.

Do-- ... ... .

Do---.. ...-- 

Do ...-_ ... .

No. 2 Wadge mine of Victor-American Coal Co., 

Mt. Harris, sec. 15, T. 

6 N., R. 87 W. 

Do ... _..-

Do... ... .-

Do-- ... ..

175 

175 

175 

175

176 

176

176 

176

Face of no. 3 nortb entry, 

main entry.

Face of no. 1 nortti entry, 

main entry.

Composite of lab NTos. 31233 

and 31234.

Face of no. 6 east entry, 

no. 7 north entry.

25 ft. from face of main 

slope.

Face of no. 6 room B panel.

Composite of A2485- 

A2487.

Wadge, middle 

coal group.

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

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

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

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

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

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

Williams Fork,.. 

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

.. do..... 

.....do. ..

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

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

.. do 

... ..do ..

31233 

31234 

31235 

A2484

A2485 

A2486

A2487 

A2488

6.9 

6.3 

6.6 

4.6

4.1 

3.9

3.9 

4.0
Do ..... 

No. 1 mine of International 

Coal Co., }6 mile northeast of Mt. Harris, sec. 15. 

T. 6 N., R. 87 W.

Do .... ...... 

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

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

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

Moorehouse mine, 6 miles 

north of Mt. Harris, sec. 

27,-T. 7 N., R. 87 W.

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

Moauro mine, NE.J4 sec. 10, 

T. 6N., R. 87 W.

176 

174 

174 

174 

174 

174 

197 

197 

197 

168a

Air course, 300 ft. from 

mine mouth.

No. 4 room, no. 1 entry, 

slant slope, lower bench.

No. 4 room, no. 1 entry, 

slant slope, upper bench.

Composite of lab. nos. 

81684-81686.

Face of no. 1 room, left of 

main heading.

Face of main heading, 

new opening.

Composite of lab. nos. 

A3031 and A3032.

Face of main drift, 340 ft 

from mouth.

 do ......

Wolf Creek, 

middle coal 

group.

 do ......

... -do ... ..

 do ... .... -

..... do ..

Lower coal 

group.

... -do .....

..... do... .

Wadge, middle 

coal group.

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

 do. ...

 .do ..

 .do. ......

 do .... ..

--...do . ..

Hes

..... do ..

 do .....

Williams Fork...

A34977 

22736 

81684 

81685 

81686 

81687 

A3031 

A3032 

A3033 

A72852

3.2 

2.6 

2.1 

2.5 

2.4 

2.3 

5.9 

6.9 

6.4 

1.7
196 CONTRIBUTIONS TO ECONOMIC GEOLOGY

O a>

a

3 

fl

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6-o 

o 

J

I 

S

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a

3

s

3

 ^ 

 O

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^

2

3 

%

so

 ->

I) 

a »

a. 

s

-o

o 

3

5 

J

r»

19 

3

35

^

3 ^

5

A J 

q 

<)

-1

bfl TTlfT

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noSXxo

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Locition mine io 

 o.

Mine andlocation

Knob district Pilo 

oooc

O^COO r IK! !!!! III! !!!S !

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 O

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Williams Fork...

b» 0> 

CO

CO hCO CO

c c

jj"c3

a> g d>

5s. dft

-"^ S 4

 5 i a>

heading, Face maiBolft lower bench, 200 in

from mouth.

(N

^2*fc&3 oc 

1

T:

Headinj olf entry, top

bench, It infrom 200 

momtt.

ci

&

00 ®

tf

>

t 0)

c

c

T 

1

S

0

0

bend, ft lower in200

from mouth.

oo o O5 t*-

CO 00 CO "J

1111

c

"C

c c

c c

4

c

 c

c

T:

Williams Fork...

c

T:

& ass a a 2 S-^-S o o a 5*s £ & 

4 35 .M.S § 1a o 1 5S Sen 

~ oflJa co . «

"OM ^ Se ^"s s"s 

o§ &Sjg =33 §g «i ass^ sa as g co a, cj'g g g g g

l-< S SS d ±J d ^ S 0 C3 S S

 N rH < * £< 

S CM CN N

03 O rt y

0

ft
Do.....................

Do..-.......-.... ...

Do-.. ..............

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

Coal Co., on Craswford 

tract, 12 miles NE. of 

Hayden, NEJi sec. 27, T. 

8N., R. 87 W,

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

miles north of Milner, 

SEK sec. 28, T. 7 N., R. 

86 W.

miles south of Pilot Knob 

Mtn., SWH sec. 36, T. 

8N., R. 87 W.

1 mile south of Pilot 

Knob Mtn., SWM sec. 24, 

T. 8N., R. 87 W.

New Ducey mine, 1 mile 

southwest of Pilot Knob, 

NEM sec. 24, T. 8 N., R. 

87 W.

?11

211

?11

211

210

210

141

219

207

205

75 ft from dike, 260 ft from

mine mouth.

mine mouth.

A3043-A3046.

of mine mouth.

entry, 95 ft from mouth.

of mine mouth.

mine mouth. 

100 ft north of mine mouth.

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

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

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

.....do ----.

Wolf Creek (?),

Middle coal 

group.

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

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

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

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

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

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

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

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

...-do ------

 .do 

lies---.- .

 do.... .

-. do. -- .

.. do 

A3045

A3046

A3047

A3048

A3039

A3040

A3337

A3049

1946

A3034

a 2

fi 3

10 1

4 9

fi fi

5 3

fi 8

5 7

5.9
TA.BLE 1. Analyses of coal samples from parts of Routt and Moff

Mine and location

NTo. 

on

map

Location in mine

Coal bed and 

group

Formation

o

a

£>

*

tkD

 a

2^

Pilot Knob district Continued

Block mine, NEJ^ sec. 24. 

T8 N., R. 87W.

Prospect on Shelton tract , 

7 miles north of Deep 

Creek, SEK sec. 32, T. 

9N\, E. 87 W.

152

Main -west entry, 1,000 ft 

north of main entrance.

25 ft from mouth of prospect pit.

Lower coal group 

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

lies..... ...

-....do.. ...

A72345 4. 

A3051 5.

Hayden district

Babson mine, onDry 

Creek, 7 miles south of 

Hayden, NE}£ sec. 4, T . 

5N".,B. 88 W.

Do.. - - ....... .

Do.. - - -.... -.

Dry Creek mine, Coryell 

CoaJCo.,onDry Cnek, 7 

miles south of Hayden, 

NEMsec. 4, T. 5N., R. 

88^1.

Do.... ....... -

229 

229

229 

230

230

Left drift, 150 ft southwest 

of mine mouth.

No. 13 room, SCO ft from 

mine mouth, 100 ft north 

of main slope.

No. 7 room south, main 

slope.

600 ft from mouth, No. 5 

room south, 200ft south 

of main slope,

North entry, 500 ft west of 

mine mouth.

Dry Creek, upper coal group.

 do. .

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

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

 do ..........

Williams Fork... 

.....do.. ...

. .do... ..

.....do. .. ..

.....do.. ...

93303 

B 57509

A34975 

B57510

93305

2.

7.

5

6.

2.
Crow Bar Mine, Dry

-Creek Coal Co., SEJ< 

sec. 4, T._4 N., R. 88jW.

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

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

Do 

Sleepy Cat (lower bed

abandoned), NWJ4 sec. 

16, T. 5 N., R. 88 W.

Gary mine, 10 miles southwest of Hayden, SWJ< 

sec. 31, T. 6 N., R.89W.

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

Lindholm mine on Sage

Creek, 9 miles southeast 

of Hayden, sec. 30, T. 5 

N., R. 87 W.

Mine on Sage Creek, near

mouth of canyon, (lift seam), sec. 2, T. 5 N., 

R.88W.

Rose mine, 3 miles southwest of Hayden, NWJi 

sec. 18, T. 6 N., R. 88 W.

Stroud mine, 3 miles southwest of Hayden, NWJ^ 

sec. 18, T. 6 N., R. 88 W.

231

?31

231

231

237

33f

335

15F

246

?44

?43

Tippie~sampie~(50~tons) ...

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

entry. 

Face of no. 1 left room .....

mine mouth.

mouth.

mouth.

..... do .

.....do .-.

 do .

 do ..

per coal group.

coal group.

group, 

- do. - -.

.. do ..-.

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

.. do ..... .

 .do- - .

-. do . .

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

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

 do 

----do ---..

-...do ......

.. do .- 

D54454

D54455

D54456

D54457

A23375

22775

92663

94195

2032

93317

93318

7.

7.

3.

4.

4.

3.

2

5.
TABLE 1. Analyses of coal samples from parts of Routt and Moff

Mine and location

No. 

on 

map

Location in mine

Coal bed and 

group

Formation 0

X>

05 

A

Air-lo

Hayden district Continued

Lorella mine, 1M> miles 

north-west of Hayden., 

SE^ sec. 32.T.7N., R. . 

88 W.

"Qhosthole" mine (Wm. 

.Kleckner) , 8 miles north 

of Hayden., NWJi sec. 5, 

T. 7 K, R.88W.

White mine, 9 miles east of 

Craig, NEMsec. 4, T. 6 

N., K.89W.

F. M. Hinclman mine, 3 

mileseast of Craig, SWJ^ 

sec. 33, T. 7N., R. 90 W.

Haughy mine, 1% miles 

east of Craig, SWJ£ sec. 

33, T. 7jSr.,K.90W.

Jim Campbell mine, 6tniJ.es 

east of Craig, NWJ< sec. 

30, T. 7 jST.,R.89W.

Seymour - mine, 12 miles 

northeast of Craig, SEJ< 

sec. 18, T. 8N., R. 89 \V.

258 

251 

334 

423

422 

341

363

Main heading, 475 ft northeast of mine mouth.

Small room, left of heading.

Face of north wall, main 

entry.

Small room off main heading.

Small room, right of main 

entry.

125 ft from mine mouth. . .

Lorella bed - .-

.....do ...... ._

..... do ...

Campbell bed. __

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

. .do ------

. .do.. -...-.

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

Fort Union..... 

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

94193 

94194 

92662 

A3770

92665 

92669

93312

5

4

8

3

9

7

3
Do...... ...............

northeast of Craig, SWJ£ 

sec. 18, T. 8 N., R. 89 W.

east of Craig, SEJ4 sec. 

17, T. 8N., R.89W.

head Creek, SJ^sec. 26. T. 

9N., R. 88 W.

Potholes, Elkhead Creek,

upper of two coal beds 

exposed below large sill, 

NWJ^ sec 25 T 9 N R 

88 W.

Potholes, Elkhead Creek.

lower of two coal beds 

exposed below large sill, 

NWJ< sec. 25, T. 9 N., R. 

 88 W.

363

36?

361

an

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

. do ......

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

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

.. do ...

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

...-.do _ 

...-do .--

.....do ..

...-do ......

A2700 8.

93313 3.

93314 2.

A3168 6.

A3166 3.

A3167 4.

Williams Fork Mountains

Sun mine (formerly 

Green), in Hayden 

Gulch, NEJ£ sec. 12, T. 

4N., R.89W.

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

Do 

264 

264 

264 Face of main heading, 215 

ft from portal.

Bed T, lower 

coal group.

.....do ... .

..... do .....

Hes...._.. __ .

..--do .....

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

2210 

9693 

C33662

3

4.

3.
TABLE i. Analyses of coal samples from parts of Routt and Moffa

Mine and location

No. 

on 

map

Location in mine

Coal bed and 

group

Formation 0

a 

3

Air-drying loss 

Williams Fork Mountains Continued

Rice mine (also Iknown as 

Webber mine) , in Hayden Gulch, NEJ£ sec. 12, 

T 4N., R. 89 W.

Core hole, NEJ4 sec. 34, 

T. 5 N., R. 89 "W.

Do- .. . ......

Do- -. ............

DO ....- ..... ...... _

Do ..- ...........

Do .... _ ... ___

263 

325a 

325a 

325a 

32fa 

325a 

325a

190 ft in by portal to main 

heading.

Depth: 142 ft 9 in. to 148 ft 

3 in. (8 in. bone rejected) .

Depth: 196 ft 11 in to 201 

ft 8 in. (2 in. coal lost).

Depth : 263 ft 2 in. to 264 

ft 6 in. (1}4 in. coal lost).

Depth.: 284 ft 4J^ in. to 287 

ftlLn. (6}^ in. coal lost).

Depth: 315 ft 3J^ in. to 316 

ft 8M in.

Deptn: 329 ft 4 in. to 330 

ft 6 in

Bed R, lower 

coal group.

Bed D(?) lower 

coal group.

Bed C(?) lower 

coal group.

B zone, lower 

coal group,

lies ..........

 do 

 .do -

.....do - 

 do - -..

 do -..

 do .

B34465 

D24614 

D24615 

D24616 

D24617 

D24618 

D27658

6.

0.9 

1.

1.

1.

1.

3.
Core hole, SWJ4 sec. 26, 

T. 5 N., R. 89 W.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

310a Depth: 423 ft 5 In. to 431 

ft (10 in. bone and ironstone and 1 ft 1 in. coal 

lost).

310a Depth: 451 ft 8 in. to 464 

ft 2 in. (}/£ hi shale rejected, 2 ft. 5>i in. coal 

lost).

310a Depth: 513 ft 6 in. to 515 

ft 10 in. (2>i in. coal lost).

310a Depth: 527 ft 4 in. to 532 

ft 6 in. (1 ft 2 in. core 

lost).

310a Depth: 582 ft 6 hi. to 588 

ft 8 in. (3 in. shale rejected) .

310a Depth: 591 ft 4 in. to 592 

ft 6 in. (1^ in. bone rejected) .

Depth: 599 ft 10 in. to 605 

ft 2 in. (5 in. bone rejected, 3J£ in. coal lost).

310a Depth: 613 ft 4 in. to 617 

ft 4 in. (9 in. bone rejected, 3 in. coal lost).

310a Depth: 631 ft 7 in. to 634 

ft 7 in

310a Depth: 673 ft 2 in. to 674 

ft 10 in. (6 in. coal lost).

Upper bed of H, 

zone, middle 

coal group.

zone, middle 

coal group.

G and H, middle coal group.

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

zone, middle 

coal group.

coal group, 

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

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

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

F and G, middle coal group.

Williams Fork... 

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

 ..do ....... .

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

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

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

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

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

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

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

D27659

D27660

D27661

D28384

D28385

D28386

D28387

D28388

D28389

D28390

1

1

3

2

2

3

2

2
TABLE 1. Analyses of coal samples from parts of Routt and Moff

Mine and. location

No. 

on 

map

Location in mine

Coal bed and 

group

Formation

§

,0

Al

'Williams Fork Mountains Continued

Core hole, SWJ4 sec. 21, T. 

5N., R.89 W.

Do .- ... . 

Do -.. _ -

Do. ..-'- -

31 2b 

31 2b 

31 2b 

312b 

312b 

312b 

312b

Depth: 81 ft 4 in. to 84 ft 

3 in. (21A in. coal lost).

Depth: 188 ft to 195 ft 6 in. 

(1 ft 9 in. coal lost).

Depth: 215 ft 4 in. to 223 ft.

Depth: 229 ft 6 in. to 231 ft 

(4 in. coal lost).

Depth: 231 ft to 233 ft 2 in.

D epth: 242 ft 6 in. to 248 ft 

(3 in. bone rejected, 2 in. 

coal lost) .

Depth: 267 ft 2 in. to 270 ft 

3 in. (9 in. bone and 

shale rejected).

H zone, middle 

coal group.

O zone, middle 

coal group.

.. _ do. -

 do. .... 

 do. 

. __ do. _ .......

 do 

Williams Fork.. 

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

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

... ..do... . . 

 do ... ..... 

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

 do 

C99751 

C99752 

C99753 

C99754 

D2191 

D2192 

D2193

2

4

2

2

2
Do.

Core hole, NEM sec. 29, T. 

5 N., R. 89 W.

Do.

Do.

Do.

Core hole, NWM sec. 28, T. 

5 N., K. 89 W.

Core hole, SWM sec. 7, T. 

5 N., R. 89 W.

Do.

Do.

Do.

312b

313a

313a

313a

313a

312a

275a

275a

275a

275a

Depth: 372ft 1 in. to 377 ft 

4 in.

Depth: 130 ft 6 in. to 134 ft 

(1 in. bone rejected, 1 ft 

8>_ in. coal lost).

Depth: 164 ft 11 in. to 166 

ft 8 in. (8 in. shale and 

bone rejected).

Depth: 226 ft 4 in. to 229 ft 

6 in. (1 ft. bone rejected).

Depth: 259 ft 4 in. to 261 ft 

(2 in. bone rejected).

Depth: 140 ft 3H in. to 145 

ft 9 l/2 in. (4M in. shale 

and bone rejected, 7>i 

in. coal lost).

Depth: 295 ft to 297 ft 3 in. 

 (9 in. coal lost).

Depth: 299 ft 1 in. to 304 ft 

1 in. (5 in. coal lost).

Depth: 330 ft to 338 ft 4 in. 

(4ft 9 in. coal lost).

Depth: 427 ft 10 in. to 433 

ft 5 In. (3 ft 5 in. coal 

lost).

coal group.

 ..do .....

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

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

F zone, middle 

coal group.

middle coal 

group.

coal group.

zone, middle 

coal group.

O zone, middle

coal group.

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

lies---- 

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

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

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

Williams Fork... 

.....do . ....

... -do ... ...

. do ......

.. do -. 

D2194

D6281

D628:

D6283

D6284

D6285

D24284

D24285

D24286

D24287

2.2

3.3

3.1

4.2

3.6

2.4

1.0
TABLE 1. Analyses of coal samples from parts of Routt and Moffa

Mine and location

No. 

on

map

Location in mine

Coal bed and 

group

Formation o

0

4Hi

o

bo

.gS

i

*"

Williams Fork Mountains Continued

Core hole, SWMsec. 7, T. 

5N., R.89 W.

Do.-. -... _ ....

Do.. -_......._ 

Do--.... ___... ..__.. _

Core hole SVW sec 10 T

5 N.. R'.QO w!

Do ---'.. _.. -

Do - --.....-_ - -

275a Depth: 471 ft to 474 ft 3 in. 

(5 in. bone rejected, 1 ft

9 in. coal lost) .

275a np.nt.~h- 483 ft to 484 ft 2 in.

(yz in- coal lost) .

276a Denth: 488 ft 71^ la. to 493

ft 7J-6 in. (7 ia. bone

rejected) .

2758 Depth: 493 ft 7H to. to 500

ft 2 in. (9 in. bone and

403a

stale rejected).

Depth: 23 ft 10 in. to 25 ft

Q in. (2 in. bone rejected).

403a Deoth: 35 ft 8 in. to 37 ft

4 in. (10H to. bone rejected, 3 in. coal lost).

403a DfiDth: 39 ft 2 in. to 43 ft 2

In. (\Yz in. coal lost).

0 zone, middle 

coal group.

 do ...... .

 do .....

do

Lower coal

group.

-...do .-. 

 .-do - -

"Williams Fork..

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

 do -

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

lies...... ......

 do 

 do 

D 24288

D24289

D24290

D24613

D20767

D20768

D20769

.3

.0

.6

.8

2.2

3.0

2.0
Do.

DoCore hole, NWJ< sec. 10, T. 

5N., R. 90 W.

Do.

Do.

Do.

Do.

Do.

DoCore hole, NE}£ sec. 10, T. 

5N., R. 90 W.

403a| Depth: 52 ft 3 in. to 54 ft 

(8 in. coal lost).

403a| Depth: 69 ft 6 m. to 73 ft 

4H in. (2 ft 6 in. bone 

and shale rejected).

387a| Depth: 88 ft 6 in. to 100 ft 

(2 ft 2H in. coal lost).

387a| Depth: 158 ft 7 in. to 169 ft 

Sin. (3 ft 7 in. coal lost).

387a| Depth: 188 ft to 194 ft (11 

in. bone and shale rejected).

387a| Depth: 208 ft 6 in. to 210 ft 

11 in.

387a| Depth: 409 ft 3 in. to 410 ft 

10 in. (6>6 in- bone rejected).

387a] Depth: 432 ft 7 hi. to 435 ft 

6 in. (9 in. siltstone rejected).

387a| Depth: 469 ft 2 in. to 470 ft 

8 in.

387b| Depth: 326 ft to 329 ft 5 in. 

(1 ft J^ in. bone rejected).

 do - 

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

Top bed, H 

zone, middle 

coal group.

zone, middle 

coal group. .

G and H, middle coal group.

--.do - -----

coal group, 

- do -----

 do --..

middle coal 

group.

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

.....do -- .

Williams Fork- 

___._do- ......

 .do --...-

..... do . ...

..... do ...

.- do .....

.....do. ....

...-do -

D20770I 2.51

D2077l| 2.6| 

.. ID20772 1.2

D21616I 1.4

D21617I 1.5

D21618I 1. 7l

D21619! 2.1

D21620I 2.1

D21621I 2.3

D24291I . 9
208 CONTRIBUTIONS TO ECONOMIC GEOLOGY

 is 

8

e

'S

I °.

^- "O

v~, _g

*e "9

§ -3

'S' w"

IIe -5

l|l

Ultimate

Proximate

g

X

0

Is

Carbon

il « M

3

1

II

Volatile matter

.2 £

§§" 

PH'O'OS

bo

g "S

a

bed anCoal

group

and/or of Number source 

samples

ooc<;

OS 0

il IfSi slis

co co oTcJco co oWco co"

j

1

I

coco**

o

T-H 

>O

»

CO

t-,

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coos

^

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SB

^K-H

CO CO OS C<

1OCO i

00-* j

00 SO CO OS

S22^S

«^NCO2S5S

i-ITHCOCO

to »o

GO i-H O5 i <D Oi *O

;

t-^iOO IOO(N^

"" SS 338S

OOSU5O5 COCO>O«O

^H CO CO* O CO* irf 00 OS

OS T)* 1 irf O

g

CO

0

^

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o

TX

T*

O

00 *

o

o

10

o 10 »o o

CO CO CO"*

r-ocoso

00 ** CO' CO'

10. cl^ l>!'>;

oo co »o r~ 

odco^oi

OOTtlTl<10

fflt-^^,

OOstss

 *OCOO) " 5 5!

COCO i

IQ iQ O CO

jfe

V

a 

C

g

1C

1a t-5

^

>

|

i(/

<c

CO

a 

|| ^

£ R

23 <D 13 03 ^ c5

o> d o "^ a> "cS <£i- o^^. o*^«

>v ® o ^ "9 t* ' ° "r1 

fl ^ ^

1-1 9 3"3 '"'Sja trt O O S O w ^

5 a) <N g fi « »

I-S i-' "fgo 

|6 gg 1^1

III f«a III ' its fsi HI

co oo O
TABLE 3. Measured and indicated, undifferentiated, original bituminous coal reserves in 

October 1949

[By Frank D. Spencer. In millions of short tons]

Coal group and bed

Less than 1,000 feet overburden

In beds 

14-28 in. 

thick

In beds 

28-42 in. 

thick

In beds 

more 

than 42 

in. thick

Total

1,000-2,000 feet overburden

In beds 

14-28 in. 

thick

In beds 

28-12 in. 

thick

In beds 

more 

than 42 

in. thick

Total

2,0

In be

14-28 

thic

T. 3 N., R. 86 W . 

Lower coal group: 

No. 3 bed.... -__._._.........._ 

No. 2 bed. ...... ...... .........

No. 1 bed-.. _____ . _ . _ ....

Total...........................

5.70

5.70

2.44 

50.12 

19.93

72.49

2.44 

50.12 

25.63

78.19

T. 4 N., R. 85 W.

Middle coal group:

Wolf Creek bed ................

Lower coal group: 

No. 3 bed.........................

No. 2 bed........ .................

No. 1 bed............... ...... ....

Total...........................

6.02

6.02

13.55

18.94

29.93

34.50

24.02

120.94

6.02

13.55

18.94

29.93

34.50

24.02

126.96

22.66

22.00

22.00

22.00

T. 4N., R. 86 W.

Middle coal group:

Wadgebed..- ___________

Wolf Creek bed...... .............

Lower coal group: 

No. 3 bed.........................

No. 2 bed.........................

No. 1 bed.........................

Total..........................

18.49

11.90

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43.88

31.37

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210 CONTRIBUTIONS TO ECONOMIC GEOLOGY

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23.79

45.57

27.36

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3.68

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37.43

45.57

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314. 01

T. 5 N., R. 87 W.

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Total.........................

3.04

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212 CONTRIBUTIONS TO ECONOMIC GEOLOGY

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GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 213

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Middle coal group:

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sandstone member. .--_-.---.---

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member......... _____.__..__.-

Lower coal group: 

Bed 180 ft below top of Trout

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Bed 350 ft below top of Trout

Bed 400 ft below top of Trout

Bed 408 ft below top of Trout

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Ducey mine bed (500 ft below top 

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Bed 520 ft below top of Trout 

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Bed 570 ft below top of Trout 

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Bed 700 ft below top of Trout 

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Bed 70 ft below bed of Block or 

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Bed 100 ft below bed of Block or 

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Total.... ___.___.___._._.____.

6.85

6.85

1.62

6.49

5.92

8.06

99 no

37.24

45.97

9.04

1.02

1.34

7.80

8.22

7.17

4.38

11.17

23.52

26.84

19.56

23.51

263.23

8.47

37.24

45.97

6 49

9.04

1 (19

1.34

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7.17 4

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8.06

26.84

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23.04

23.51

13.41

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3.85

8.52

26.47

38.55

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7.25

2.78

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34.30

16.75

11.76

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2.78

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5.

5.6
TABLE 3. Measured and indicated, undifferentialed, original bituminous coal reserves in 

October 1949 Continued 

[By Frank D. Spencer. In millions of short tons]

Coal group and bed

Less than 1,000 feet overburden

In beds 

14-28 in. 

thick

In beds 

28-42 in. 

thick

In beds 

more 

than 42 

in. thick

Total

1,000-2,000 feet overburden

In beds 

14-28 in. 

thick

In beds 

28-42 in. 

thick

In beds 

more 

than 42 

in. thick

Total

2

In be

14-28 

thic

T. 9 N., R. 86 W.

Middle coal group: 

Bed 350 ft above Trout Creek

Bed 200 ft above Trout Creek

Bed 100 ft above Trout Creek

Bed on Trout Creek sandstone

Lower coal group: 

Bed 180 ft below top of Trout 

Creek sandstone memberBed 200 ft below top of Trout

Bed 250 ft below top of Trout 

Creek sandstone member. _ _

Bed 500 ft below top of Trout

Bed 880 ft below top of Trout 

Creek sandstone member

Bed 1,250 ft below top of Trout 

Creek sandstone member __ .

Bed. 1,400 ft below top of Trout 

Creek sandstone member __ .

Total .- _ ._ _ ...

2.77

3.19

11.34

7.16

24.46

11 64

8.14

7.69

10.84

6.60

10.39

27.92

83.22

2.77

3.19

11.64

8.14

7.69

10.84

6.60

10.39

11.34

27.92

7.16

107.68

3.86

6.68

10.54

0.61

1.06

1.03

5.38

14.08

22.16

0.61

1.06

1.03

5.38

3.86

14.08

6.68

32.70
T. 9 N., R. 87 W.

Middle coal group: 

Bed 200 ft above Trout Creek

Bed 350 ft above Trout Creek

Bed 250 ft above Trout Creek 

sandstone member __ ... __ __

Bed 100 ft above Trout Creek

Bed on Trout Creek sandstone

Lower coal group: 

Bed 180 ft below top of Trout

Bed 200 ft below top of Trout

"Bed 250 ft below top of Trout

Bed 500 ft below top of Trout

Bed 880 ft below top of Trout

Bed 1,250 ft below top of Trout

Total.... .....................

0 OK

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3.82

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T. 3 N., R. 90 W.

Middle coal group: 

Bed in H zone (400 ft above 

Trout Creek sandstone member)............................

Total.........................

14.00

14.00

14.00

14.00

T. 4N.. R. 88 W. 

Middle coal group: 

Bed in if zone. ___________

Bed in G zone ______ _ __ .

Bed in F zone... ................. 0.16

6.17 

48.34

6.17 

48.34 

0.16 
218 CONTRIBUTIONS TO ECONOMIC GEOLOGY

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§«

iC cD CO 

1C CO 1C

COO

CO

v\

CO O 

rH O

CO "

1C 

CO

j 1

i |

i j

i

§

CO

5

CO

I

iC CD CD 

iCr^wS

coco

iC O CD

coco

is

aea inzone. f -- - 

Lower calgroup: 

v^nA

t rH

!E5 

!co

2rQ^

^05

a

5 rH

X) ^ 

% GO

iT3 rH

g 3

1C rH

CO

IN

CN 

IN

CO

8

toi

CO 

rH

CO 

(N

IN 

IN

06

s

IN

O

rH 

CN

8

IN

v4 bed--.------------- ------ Trout Bedofft below 1,275 topCreek member- sandstone .....

TVlfnl

>

H

345016 55-
220 CONTRIBUTIONS TO ECONOMIC GEOLOGY

gj l_t

eo-rt

"&

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il

g §

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si s

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3

^2

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a

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a

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"3

o

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§

U0

irioi

T)1CO

o>o 

oo

irfoi

g

g

w

g 

<.

g

rMiddle coalgroup:Wnripp bfifl

S

c

o

CO

g

a.

a

Wolf bed- Creek_........ __ ..

§

o

a

o

00

cr

«

'o 

fH

^SS..^.§2S

0,

c«

00

c<

00

00

Middle coalgroup: 

Jhe.A _.__-._.-__ 

Tj

Tj

1

EC

 s

PC

S

S

<NrH

COi-H

83

«8

S

:

IN

CO

O 

CO

s

**

ti I

2 SS 

ggg

maa:

.S.S.S

iii fflrtp:

co

CO 

CO

CO

CO

CO

CO

(M

OJ

OJ

a

:

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tt1 1 1 s s s o o o

N « « 

OO&H

SS3 

fflfflffi

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s

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EH
TABLE 4. Inferred original bituminous coal reserves in parts of Routt and Mojf

[By Frank D. Spencer. In millions of short tons]

Coal group and bed

Less than 1,000 feet overburden

In beds 

14-28 in. 

thick

In beds 

28-42 in. 

thick

In beds 

more 

than 42 

in. thick

Total

1,000-2,000 feet overburden

In beds 

14-28 in. 

thick

In beds 

28-42 in. 

thick

In beds 

more 

than 42 

in. thick

Total

2,00

In beds 

14-28 in

thick

T. 4 N., R. 86 W.

Middle coal group:

Wolf Creek bed. ____ . ___ .

Total... ___ .................

8.58 

79.10

87.68

8.58 

79.10

87.68

T. 4N., R. 87 W. 

Middle coal group:

Wadge bed ............ ...........

Total...........................

8.46

8.46

5.68

5.68

8.46

5.68

14.14

T.5N., R. 85 W. 

Middle coal group:

Total...........................

1.10

1.10

1.10

1.10

T. 5 N., R. 86 W. 

Middle coal group:

Wadge bed. ......................

Wolf Creek bed.. ...... ...........

Total................ ...........

5.71

5.71

46.04 

41.80

87.84

5.71

46.04 

41.80

93.55

38.28

38.28

50.58 

227.05

277.63

38.28 

50.58 

227.05

315. 91
222 CONTRIBUTIONS. TO ECONOMIC GEOLOGY

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8S

coco >o

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ooioco

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CO CO OS

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iddle coalgroup:

i

%

i

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1

5

CO

§

r 

O

s

s

g

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3

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Wadge bed.-- bed._ Cieek Wolf

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cofSS

CNCOVH

COOS

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ssii-i-*

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coal iddiegroup: 

Lenaox W.-_- fced..-_- Wadge bed. Creek Wolf

o

IN

8

s

00

IN

CO 

CO

o1-H

8

ir

s

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15

to

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£

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3

y

-I

2

'x

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OS

^

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CN-*05

to co co INT)I IO

CO-* OS

oo to oo

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iddle coalgroup: 

bed...,. Lennox bed Wadge ... bed.. Creek Wolf

8

S

S

Si

S

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CO

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Bed inH zone..... ._-- ..-. Bed inCzone..........--- ..

i os'

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Bed Jzone... in .-.-..--- ..... Total-...-- - - ..-. 
GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 223

i

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« 

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in

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SI

CO f*

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Middle coalgroup: 

Wadge bed.... _... .

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ri 

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00

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H

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OcO

p

£

£

S

Middle coalgroup:Tlp.d inG 7.nnA

CO 

(N

c< 

eo

S

o

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>o

S

o

in BedF zone __.... -

S

00 

CO

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1

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£

(N Cf

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S

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Middle coalgroup:Warlffe hprl

8

8

8

1-1 

CO

8

t,

rg

Creek Wolfbed..... ...........

c

c

s

IT

oc

S

c

?

c

?* 

5"c

" " '^

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«

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5

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Middle coalgroup: Wadge bed _____________

S

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Wadge be. .......... ......... 

"^

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J

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1
224 CONTRIBUTIONS TO ECONOMIC GEOLOGY

i

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IHSI

IW

SM

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u XJ

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hi OS

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05gO

Pn

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coal Upper group:

Creek bed... Fish ---- -_ _

3 9a

Tf $°

88

"5 

 u o 1

So

;zi

inH

e»«- *o 0

35 

<**

§3E

2S

coal Upper group: 

Bedof tac.245 . _-....._ .

Ciftp.lc be,dFish _...

S3 ?

E 

if

CM V

c?

cr

T 1 o1

5 5

s

CO

Tjt

o 

eoc

CO

eo

Upper coal group: 

Creek bed.... Fish___ .........

Tf cF

Tf

C 

cr

C 

CO51

i

tf

<£> ^

5 

& i^

IT *&

 H9S

Upper coal group: 

bed... DrvCmek _...

Q N

CO 

r-4 ««1 S

CO

Creek bed... Fish____ ....__ 

IT

CCg£S

«3

COgoo

cog1 .
T. 8 N., R. 87 W.

Lance formation:

Total.. ......................

9.92

9.92

9 92

9 09

-

T. 7 N., R. 90 W. 

Ft. Union formation:

Lance formation: 

Bed of loc. 407a _ .............

Total... ..... . .-. . .. . 

1.14

12.22 

14.18

27.54

16.12

.66

16.78

25.94

25.94

1.14

28.34

14.18 

.66

25.94

70.26

T. 8N., R. 88 W. 

Lance formation: 

Bed of loc. 251... -.............

Total..........................

4.01 

21.17

25.18

4.01

91 17

25.18

T. 8 N.. R. 89 W. 

Ft. Union formation:

Lance formation: 

Bed of loc. 251-.... ..............

Total-... .-....-. . 

13.63 

.31

13.94

24.79

24.79

67.91

67.91

106. 33 

.31

106. 64

T. 8 N., R. 90 W. 

Ft. Union formation:

9.49

9.49

6.78

6.78

14.50

14.50

30.77

30.77
226 ^

13e

 oI

1CHA

(4

< EH

"S3

Total allinoverburden 

categories

2,000-3,000 feet ovrburden

1,000-2,000 feet ovrburden 1

1 o§1oH

03

1W

i§ '3 M O

EH

pi

!N

is j«

"o

EH

IHII iisi

^ o 4^ 30

lea 

|N

 |s

l§ .-a

fs^i

Formation coal andbegroup, or 

g

CO8

CO«a

cc 

co

IN

(0

CO

Ft. Unionformation: 

bed Seymour Bed ftabove 50_..

o 

en

COo

CT> 

CO«S

CO

CM

(0 «|

co oio

1-lTf

Sg

C7 «:

1H

Lance formation. :Bed Ion.2fi2 of 

S

 ^§

Tj ^

00

00to

^HJ

tc

-HaH

CO

I

00-s

s?

00s

IH«

00

bed loc.Bed ofbelow 262.... 50ftBed loc. of222.........-._ _Total.... ............ ......._ 

00 

CO

» 

z,

en H

£ «£aS

(Xsa

raj

S Sa0!

*o 

CO

0( CV ; CN >0

05 

IN

COdSs

bed Bedloc. 262.... 50 below offt

u-3

t-a

a t^"*

ir5S

s 

t>10j
GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 227

3Kp|

s<

t-<

s

*"

s

88

COM

228

»<NOO

32

OOP)

as

odN

U5C iO«f

SW

«?c ?5i/-

co'tN

00

CO

O

8

p

cformation: Lance 

bed loc.251 Bed 50above offt... Bed loc.of251 ..-.....- ........ Lorella bed..Bed above 400ft_ .Lorella bed.. --------- ----below Lorella bed..Bed 100ft.... Lorella bedBedbelow 50ft_ ...

8

CO

£

3

8

S 

fr

S3

CD 

CO

CO 

CN

|>

8' 

fc

rH

CN r- o^o ex

CO CO CO »H

e<

CO

CJ 

CC

f

s

a

formation: UnioFt. 

(loc. Gulch mine BedBoone of

QAO'V

CO

I-ir

or-uc<

 c 

c

113 0

C

ex

8

ss

cnoot *S-<i

CO i-H

o n

CV

o

0

i-H

01

T|

Lance formation: 

White mine... Bedofloc. 334, .... Bed loc.of407a . .... ____ 

TlnH nt l^nOKI

CO

O5

-»<

I

rco

r5 2

S

c ^

 »

r^

cc 

r5 

j

^ 1 

I

' 

4

%

65

S5 

in

H

COi-HCOC 

OO '«5C

oi

CM M 

Oi N*

sss

°S3J

os c s r*-

CDi^CO

8 s

s

OJ

s s

Oi CN i-H tC P

coal Upper group: 

bed... P---------------------- --.JVbed... -.- L bed. ....... ...................

28 S 

2S5 g

Ci

8 3 

§5 2FH

2 S

j oi

§8 t

28 R

S

OJ

§ S

S 2

2 1

K bed... .................. ...... below K bed............ Bed 12 ft

Tntal

J

^
228. CONTRIBUTIONS TO v ECONOMIC GEOLOGY

October Continued of 1949 

Frank D.Spencer. millions shorttons] [By In of

pq o

Total inalloverburden 

categories

1

1 

o

cJ

overburden 1,000-2,000 feet 

1

!o 

cp

 2

O

o

i

5

fllgl

IN

|I4

3o

pi

IN

M *"

3o

l§ll^

-!.a|

01

'o

fiJli

1M

IN

Formation andcoal bed group, or 

T. 5N., R89 W.

' g5 'CO 00 00 O5'«O i-t IN CO 00 i < CO CN r~ t^ TH » I oo CO

 -ssssss

§

c

s

er

«

O>H

500<

o

a

I

l| 

|S

2

1x> 

0;

00

CO

^"*

30 FH CO »-t CN 

NiOOOCOi-

=°2§S5

00 COO 

CNO900

COO'rl

gS8Sg

1-1 c<

c§?

^ c

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.0.1

oc

CO

« §5

°S8§5!

23 S"1'

iioSSs

tr 

t~s

tow

S52

n

&

S§?

COCO

^^ 

fc!S

1

^

C

1

£

bTj

g 

ts

g

S

c

§

10 co r-- bO3 O CO i-H 

»-i CO CO CO

s

 o

en

§

Upper coal group: 

/Jbed........... ____ 

CO

o

CO

CQI Oc 

« c

8J

we

 d' 1*

t

OS

ao«

10 S?

O£H 

* W

s'-o

§J! ^

1

s

3

i

a

Total.... ......................
GEOLOGY, MINERAL FUELS, -ROUTT AND MOFFAT COUNTIES, COLO. 229

OCOX5 T-I -icow r~ 

co^^ g

c 

c<-

c 

f

c

Lance formation: 

Lorella bed--. ____ ______

:

00

CO

Tf

t

1 

*

 *< (

Bed Stroudmine of....__ _

g

5 S

S

 o

: T*

S

** "5

a 35

Q <N

 O

D

 O

Upper coal group: 

K bed............. ..............

§

8

d

CO

2

trH

1

d

CO

2

3o

t* r-t W CO to O *H CO S ?5 fH

 <!< i-i CO CO -H jH CO 00 CO i-i «j

s

 *

r00 1-

 91^

?

t^

 Lance formation: 

Bed Whitemine of__ .... Bed Stroudmine. of_.

S5 t

00 5

S

oo co ?

0! j;

g

a

Bed Rosemin of..... Beds loc.of334a: 

Bed 3 -. . ..._.....__ Bed 2.............. .......

t >* O IT

 a « ?9tN

^H CD 

CM CO>-

CM'OO

Es C£

s «

^ c

c

Bed I........................Upper coal group: 

Sbed.. .............. .

 0' 

00 '

c

2

"SI 

%* 

^

3$

38

c -

?S

t;

 0

:

Bed loc.of407a-._. ..__.....____.

S

§

o

g

1

§

S

o

3o

^

Efe

K

CO

h

S8S888

-3 SS?5

us

IN

10

O; 

"O

C

t

Uper coal group: 

Bed loc.407a..- of................

f-t~

3

3K

<*«

 t

£

3

d

 t

ii

Q<£

Kg

5

S

a

8

8

888

So-g?3

S

c<

1

o

8

T 

a

fc

8 

§5

-d

JSfc<

§

ac

IN 

<C

CCt^

s

i

o

8

05

s

(X

CO

"c
230

ffl o

iC3

I s!

s

oi

S

>o

OJ

§

Upper coal group: 

bed FishCreek -. ....... 

05

S

01

IT

o:

S

a

1

! 

4

s

CO

CO

3

?

2

Upper coal group: 

Bedof loc.2iS.. .................

S.

«

9

eS

er

| > H

£

fc

H

CO 

00

o

CO 

CO

o

1-4

CC

cc

§

s

Upper coal group: 

bed... Dry Creek --" .. 

g

c5

c>

*

CC

§

1

1H
GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 231

fc

z 

«

 as

:U9

iH

5 

£

(N

Tjl

s

N «<

8

c<

9> c-<

coal Upper group: 

if bed______ .- _.-.-

9 

S

9 

g

p 

S

c

s

f

c >

H

^'

S

«

£CO

H

S8§ 

i^g2

?3 

SI

S

CD 

l>

S3S

Sss

S

8

coal Upper group:

S

I CC f-

 S 

JJ

s

8

f4I-H

!

0 

o

p

8

<>

:5

CO

00

o

§

N

<N

00

g

3

c

8

c<

rH

<N

oc

s

1£
TABLE 7. Original bituminous cod reserves in parts of Routt and Moffat Counties, C

[In millions of short tons]

Township

Less than 1,000 feet overburden

In beds 

14-28

thick

In beds 

28-42

thick

In beds 

more 

than 42

in. 

thick

Total

1,000-2,000 feet overburden

In beds 

14-28

thick

In beds 

28-42

thick

In beds 

more 

than 42

thick

Total

In 

1

th

Measured and indicated, undifferentiated Moffat 

T. 4 N.f R. 90 W... .. . --.-

T c XT "p on \?v

T. 6 N. F R. 90 W. . ..- - .

Total . ..... ... ...... 

25.58

25.58

21.02

21.02

14.00

33.38

171.62

219. 00

14.00

33.38

218. 22

265.60

12.13

12.41

24.54

1.37

17.74

19.11

79.79

46.55

126. 34

93.29

76.70

169. 99

Measured aud indicated, undifferentiated Routt 

T. 3 N., R. 86 W..... - .

T. 4 N., R. 86 W..... -.-. -- ...

T. 4 N., R. 87 W....._ -

T. 5N., R. 85 W..... ..-....._---_-..

T. 5 N., R. 86 W....._. -- .

T. 5N., R. 87 W..... -.--.....---_-..

T 6 N R 86 W

T. 6 N!', R. 87 W..... . _. .

T. 7N.f R. 86 W....._. .... ..--_...

T. 8N., R.87 W..... .-.._.__...___..

T. 9 N., R. 86 W..... -- .. .___.

T. 9N., R.87 W..._. -- . -- ...

T. 4N., R.88 W..... ............ ...

T. 4 N., R. 89 W..._. .......... __ ...

T. 5N., R. 88 W....._ - . ...

T. 6 N., R. 88 W..... _ ... __ ...

Total ._....._.-.- .- ...

2.92

3.02

1,62

.48

6.85

40.88

55.77

5.70

6.02

30.39

2.65

34.08

5.14

48.12

6.31

7. 65

22.09

24.46

16.08

.16

1.99

30.23

241.07

72.49

120.94

322. 09

36.07

142. 91

377. 51

42.71

55.33

328.70

4.47

224.83

46.23

263. 23

83.22

97.50

5.83

178.57

476.76

31.25

2,910.64

78.19

126. 96

36.07

145. 56

411. 59

42.71

63.39

379.84

232.76

54.36

292. 17

107. 68

16.08

97.66

5.83

180. 56

547. 87

31.25

3,207.48

1.53

.52

12.10

20.96

35.11

5.09

22.56

32.01

3.89

26.47

10.54

17.96

7.12

37.67

163.31

22.00

103.23

21.61

42.22

291. 45

4.19

359. 91

9.43

108. 33

1.24

216. 18

22.16

24.77

24.06

36.34

300. 04

82.80

1,669.96

22.00

108. 32

21.61

42.22

314. 01

4.19

393. 45

9.43

108. 85

5.13

254.75

32.70

42.73

24.06

43. 46

358.67

82.80

1,868.38
Inferred Moffat County

T. 6 N., R. 90 W_. .............. ......

. Total... ..--.--.. . ...I....... ...

77.71

77.71

77.71

77.71

Inferred Routt County

T. 4N. R. 86W_. __ 

T. 4 N. B. 87 W__ ...-. -.

T. 5 N. R. 85 W__ ....................

T. 5 N. R. 86 W..... .................

T. 5 N. R. 87 W _____.._.._._. -

T. 6 N. R. 86 W..... .................

T. 6 N. R. 87 W........ ..............

T. 4N. R. 88 W .._ ........ ........

T. 5N. R. 88 W. .......--..--.......

T. 5 N. R. 89 W_... .__..-..--..... ...

T. 6 N. R. 88 W....... ...... .........

T. 6 N. R. 89 W......................

Total..... .. _ -..-..... _ . _ .

8.46

1.10

5.71

13.44

7.98

.74

42.21

87.68

5.68

87.84

226. 34

8.99

13.45

151. 02

4.68

585.68

87.68

14.14

1.10

93.55

239.78

16.97

18.23

151. 02

5.42

627.89

38.28

4.40

.7.94

.30

12.13

63.05

277.63

104. 20

5.93

123.75

.58

88.56

301. 14

154.10

21.30

1,077.19

315. 91

104.20

10.33

131. 69

.88

88.56

313. 27

154.10

21.30

1,140.24
TABLE 8. Original subbituminous coal reserves in parts of Routt and Moffat Counties, 

[In millions of short tons]

Township

Less than 1,000 feet overburden

In beds 

30-60 

in. 

thick

In beds 

60-120 

in. 

thick

In beds 

more 

than 120 

in. thick

Total

1,000-2,000 feet overburden

In beds 

30-60 

in. 

thick

In beds 

60-120 

in. 

thick

In beds 

more 

than 120 

hi. thick

Total

In 

30

i

th

Measured and indicated, undifferentiated Moffat 

T. 5 N., R. 90 W. _.... __....___. 

T. 6 N., R. 90 W .....-_-...-_.._ 

T. 7 N., R. 90 W ........ ............

T. 8 N., R. 89' W. ....... ............

T. 8 N., R. 90 W........ ....... .___..-

T. 9N., K. 89 W. ....... __ _____...

Total... __ ......_.............

49.76

27.54

13.94

9.49

3.62

104. 35

46.85

62.18

16.78

24.79

6.78

157. 38

25.94

67.91

14.50

108. 35

46. 85

111.94

70.26

106.54

30.77

3.62

370.08

9.00

.28

9.28

9.00

.28

9.28

Measured and indicated, undifferentiated Routt 

T. 5N., E.86W.. ...... .............

T. 5N., B. 87 W__..._ ........ _ .....

T. 6N., E. 86 W. ...... ......... .....

T. 6N., R.87W. ...... ..... __ .....

T. 8N., K. 87 W. ...... ..... __ .....

T. 9N., E.87W. ...... ..............

T. 9N., R. 88 W....... __.............

T. 7N., R.88W....... _..--......-

T. 7N.. R.89W.. . . .............

T. 8N., R.88 W.... .................

T_ 6N., B.88 W....... ..............

T_ 5N.. R.89 W. ... __ . ....

T. 6N., B.88 W........ .... _ ......

T. 6N., E.89 W...... ....... _ ......

Total..- _...... ..... __ ......

38.49

30.32

3.04

30.73

9.92

8.33

47.28

26.85

7.67

25.18

42.86

47.03

7.41

46.10

371. 21

26.17

.87

30.81

14.49

115.24

170. 04

30.22

109. 05

496. 89

4.01

19.92

29.18

19.07

106. 11

178.29

38.49

34.33

3.04

50.65

9.92

63.68

48. 15

57.66

22.16

25. 18

177. 17

217. 07

14S. 74

155. 15

1,046.39
GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 235

Inferred Rontt Cuny 

m woo 5? oo

osroogo

S

CO

>o

3

CO

£E

eoo

s

a

55S! 

2§§

^S 1350 -HCO

c

\

SES'P

oooo

8

 ;

So

c

8

§

s«i

5

 <!

*

5

:£

loo

 tftfrtrtrt

22222

S

s

3

s

s

a

sp-

§ 

s

s 

g

U3

ci

1

s

03

o

345016 55 -1
TABLE -"9.**- Measured and indicatd, undifferentiated, and inferred original coal re

counties and townships, as of Octob

[In millions of short tons] - 

Township

Bituminous

Measured 

and indicated, undifferentiated

Inferred 

Moffat County

T ^l "XT "R OH W

T 4 N R 90 W

T K XT "R on w

T fi "M "R on W

T 7 N" R 90\V

T o XT "R SO W

T. 8N. E. 90W. -.. -. .- ___-....-_ -..... 

T O T\J "R flQ W

14.00

33.38

311. 51

76.70

435. 59

77.71

77.71

Routt County

T. 3 N. R. 86W..-__ - .- __ .- __ -.......-._.. _. .

T. 4N. R.86W.. _ - __ .- - __. -

T. 4N. R. 87W... __.. ..._ _ - .--- .._ -.. - .- -

T. 5N. R. 85 W... ... - - - ........ ......_..._.__.__ .._._ 

T. 5 N. R. 86W._.__.. - . __ ...- - .. 

T. 5 N. R. 87W._._. -_-- ..- .-..... .......... .

T. 6N. R. 86 W... ......... .--... _........ ...... . .-__.._-...... 

T.6N. R.87W... __.. -. .._ __......- ........................ 

T. 7N". Ri.86W... ...... .. ..-_ _-.....-_. ... -............ 

T. 7 N. R. 87 W... _ ___ .-.-_---... .._. ... 

T. 7N. R. 88 W... __ -..____--....- ..-... ............ 

T. 7N. R. 89W... ....... .- ....___......-_....... .................

T. 83ST. R. 86W... .... .-.... ......... ....... .......-...... 

T.8N. R.87W... _.... .-__-.-...--........ ................

T. 8N. R. 88W... ....... .....__ _......._....... .................

T. 9 NT. R. 86W... ..... .. ..._._......-_....... ........... ......

T. 9 1ST. R. 87V... _ .-...____......- -. .. -....... .....-

T. 9 1ST. R.88W..._-. -.. --.. . __ ....... - ............-.

78.19

148. 96

460. 80

57.68

187. 78

744. 55

46.90

63.39

773. 29

13.90

341. 61

59.49

569.40

140.38

65.40

87.68

14.14

1.10

409. 46

343. 98

27.30

150.92
GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 237

00 So r- t- !> N

O irf O r-i irf t^I

* ll^Oop

S

OI its O 

OO5CO
238 CONTRIBUTIONS TO ECONOMIC GEOLOGY

03

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al 

g

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tf

a

o

CO

"3

'£

 d

i

C3

I 

§

O

1

oo

ooo

i-HO 

0 '

Oco

*-* TO

5OTO

S3.

 *^

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^^ "O

com

i

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2

o

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GEOLOGY, MINERAL FUELS, ROIITT AND MOFFAT COUNTIES, COLO. 239

TAPLE 11. Analyses of crude oil from the Tow Creek and Oak Creek fields, Routt

County, Colo.

SAMPLE 40278

[Tow Creek field (south pool); Niobrara equivalent; 2,733 feet; sec. 18, T. 6 N., 

R. 86 W. Analysis by U. S. Bureau of Mines, Bartlesville, Okla.]

Sp gr, 0.839 API gravity, 37.2° 

Sulfur, percent, 0.17 ' Color, brownish-green 

Saybolt Universal viscosity at 100°F, 41 sec.

Distillation, Bureau of Mines Hempel method

Fraction no.

Cut at 

°C OT-p 

I*

Percent

Sum, 

percent

Spgr, 

60/60°F

API, 

60° F

Correlation 

index

ViscosIOO°'FCloud 

test, «F

At atmospheric pressure, 740 mm

[First drop, 34°0 (93°F)]

1........ ................ ...

2.... ..........................

3.... ..........................

4 . .......___.._.___.._.__

6. -............-...... ..

6..............................

7 . ... 

8.... ....................... ...

9..............................

10..... ........................

50 

75 

100 

125 

150 

175 

200 

225 

250 

275

122 

167 

212 

257 

302 

347 

392 

437 

482 

527

1.7 

2.2 

5.0 

6.5 

6.0 

5.1 

5.2 

4.5 

5.3 

6.5

1.7 

3.9 

8.9 

15.4 

21.4 

26.5 

31.7 

36.2 

41.5 

48.0

0.655 

.686 

.716 

.742 

.763 

.783 

..799 

.814 

.828 

.836

84.5 

74.8 

66.1 

59.2 

54.0 

49.2 

45.6 

42.3 

39.4 

37.8

15 

19 

23 

25 

28 

29 

31 

32 

31

Continued at 40 mm

11 .. _ ................

12........... ............... ...

13.... ... .................. .

14..... .... ..............

15 ...... ........ ... ..

Eesiduum' ...................

200 

225 

250 

275 

300

392 

437 

482 

527 

572

4,7 

7.2 

6.1 

6.6 

5.9

21.1

52.7 

59.9 

66.0 

72.6 

78.5

09.6

0.847 

.855 

.869 

.882 

.895

.949

35.6 

34.0 

31.3 

28.9 

26.6

17.6

32 

32 

36 

39 

42

41 

47 

61 

97 

180

15 

35 

55 

75 

90

' Saybolt Universal.

2 Carbon residue of residuum, 4.8 percent; carbon residue of crude, 1.0 percent.

Approximate summary

Gas oil.. _ ......

Medium lubricating distillate ... .................

Viscous lubricating distillate. ........... .............

Distillation loss. . ..................... ...............

Percent

8.9

31.7

4.5

21.6

14.0

5.3

1.4

21.1

0.4

Spgr

0.697

0.749

0.814

0.841

0. 858-0. 887

0. 887-0. 898

0. 898-0. 901

0.949

"API

71.5

57.4

42.3

36.8

33. 4-28. 0

28. 0-26. 1

26. 1-25. 6

17.6

Viscosity

50-100.

100-200.

Above 200.
240 CONTRIBUTIONS TO ECONOMIC GEOLOGY

TABLE 11. Analyses of crude oil from the Tow Creek and Oak Creek fields, Routt

County, Colo. Continued

SAMPLE 40279

[Tow Creek field (south pool); Niobrara equivalent; 2,586 feet; sec. 18, T. 6 N., 

R. 86 W. Analysis by U. S. Bureau of Mines, Bartlesville, Okla.]

Sp gr, 0.838 

Sulfur, percent, 0.16 

Saybolt Universal viscosity at 100°F,

API gravity, 37.4° 

Color, brownish-green 

42 sec.

Distillation, Bureau of Mines Hempel method

Fraction no.

Cut at 

°C °F

Percent

Sum, 

percent

Spgr, 

60/60°F

API, 60°F

Correlation 

index

Viscosity, 1 

100°F

Cloud

test, <>F

At atmospheric pressure, 746 mm

[First drop, 32°C (90°F)]

1 ...........................

2..............................

3......................

4-.. ......... ................

5.... ........ .__________.__._._

6............. ........

7......................

8... ...........................

9..............................

10.............................

50

75

100

125

150

175

200

225

250

275

122

167

212

257

302

347

392

437

482

527

1.7

2.3

5.1 '7.0

5.5

5.0

4.3

4.8

5.3

6.8

1.7

4.0

9.1

16.1

21.6

26.6

30.9

35.7

41.0

47.8

0.648

.671

.719

.744

.765

.781

.799

.815

.826

.836

86.9

79.4

65.3

58.7

53.5

4Q 7

45.6

42.1

on Q

37.8

8.0

21

24

26

97

9Q

31

01

O1

Continued at 40 nun

11.....................

12

13............................

14.............................

15 ..........................

200

225

250

275

300

392

437

482

527

572

4.7

6.3

6.4

5.8

6.4

22.0

52.5

58.8

65.2

71.0

77.4

99.4

.855

.866

.876

.889

.946

34.0

31.9

30.0

27.7

18.1

09

32

36

39

46

89

150

15

30

70

85

1 Saybolt Universal.

2 Carbon residue of residuum, 4.6 percent; carbon residue of crude, 1.0 percent.

Approximate mmmary

Light gasoline.-..-.... .-.-_.-...----..:-------.

Gas oil..- .. ................. ... 

Viscous lubricating distillate....... ...............

Percent

9.1

30.9

4.8 

22.1

11.2 

8.4

22.0

Sp gr

0.694

0.747

0.815 

0.840 

0. 859-0. 878

O. 878-O. 896

0.946

0 API

72.4

57.9 

42.1

37.0 

33. 2-29. 7

29. 7-26. 4

18.1

Viscosity

50-100. 

100-200.

Above 200.
GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 241

TABLE 11. Analyses of crude oil from the Tow Creek and Oak Creek fields, Routt

County, Colo. Continued

SAMPLE 41446

[Tow Creek field; Mancos shale; oil seep; sec. 32, T. 7 N., R. 86 W. Analysis by 

U. S. Bureau of Mines, Bartlesville, Okla.]

Sp gr, 0.960 API gravity, 15.9° 

Sulfur, percent, 0.40 Color, greenish-black 

Saybolt Universal viscosity at 100°F, 3100 sec.

Distillation, Fureau of Mines Hempel method

Fraction no.

Cut at 

°C o F

Percent

Sum, 

percent

Spgr, 

60/60°F

API, 60°F

Correlation 

index

Viscosity, 1 

100°F

Cloud test. °F.

At atmospheric pressure, 745 mm

[First drop, 59°C (138°F)]

1...... __ . _ ..

2..................

3............ ...

4 ..... ......... .

5... ........ .......

6.. .............

7. .................

8..................

9..................

10 .. . . 

50

75

100

125

150

175

200

225

250

275

122

167

212

257

302

347

392

437

482

527

0.2

.3

1.4

5.9

0.2

.5

1.9

7.8

0.829

.833

.861

.880

39.2

38.4

32.8

29.3

40

48

52

Continued at 40 mm

11........ ......

12....... ........ ._

13..... ............

14.... .............

15.................

200

225

250

275

300

392

437

482

527

572

3.2

7.2

8.8

10.9

14.8

45.6

11.0

18.2

27.0

37.9

52.7

98.3

0.898

.907

.924

.941

.954

1.003

26.1

24.3

21.6

18.9

16.8

9.6

56

57

62

67

70

48...........

62.. ...... ___ 

105..........

280 ........

Over 400--~

Do.

Do.

Do.

Do.

1 Saybolt Universal.

5 Carbon residue of residuum, 11.4 percent; carbon residue of crude, 5.2 percent.

Approximate summary

Light gasoline. _____________________

Kerosene distillate.. __________________

Gas oil... ........ ......... .. . .......... .. 

Medium lubricating distillate.... .....................

Viscous lubricating distillate. ........................

Eesiduum... _____________________

Distillation loss. ..--.-. _ -. . __ __ ......

Percent

10.1

11.6

6.3

24.7

45.6

1.7

Spgr

0.879

0. 899-0. 922

0. 922-0. 933

0. 933-0. 962

1.003

"API

29.5

25. 9-22. 0

22. 0-20. 2

20.2-15.6

9.6

Viscosity .

50-100:

100-200.
242 CONTRIBUTIONS TO ECONOMIC GEOLOGY

TABLE 11. Analyses of crude oil from the Tow Creek and Oak Creek fields, Routt

County, Colo. Continued

LAB. NO. 50-0 11

[Oak Creek field; Morrison(?), Shinarump(?); 6,314 feet; sec. 2, T. 3 N., R. 86 W. 

Analysis by U. S. Geological Survey, Casper, Wyo.]

Sp gr, 0.835 

Sulfur, percent, 0.19

Saybolt Universal viscosity at 70°F, 57.8 sec.; at 100° 

F, 44.4 sec.

API gravity, 37.9° 

Color, brownish-green

Distillation, Bureau of Mines Hempel method

Fraction no.

Cut at 

°C OF

Percent

Sum, 

percent

Spgr, 

60/60°F

API, 60°F

Correlation 

index

Viscosity, 1 

100°F

Cloud 

test, O F

At atmospheric pressure, 637 mm Hg.

[First drop, 40°C (104°F)]

i-.:... ................ ..

2......................... ...

3.............................

4......................... ...

5..................... .

6......................... . .

7..... .........i. ......... ..

8 . ..................... ..

9..................... ...

10........................ ..

50

75

100

125

150

175

200

225

250

275

122

167

212

257

302

347

392

437

482

527

0.7

3.8

4.7

5.2

6.1

5.7

6.5

8.2

0.7

3.2

5.2

9.0

13.7

18.9

25.0

30.7

37.2

45.4

0.660

.663

691

.713

.739

.761

.783

.799

.814

.828

82.9

81.9

73.3

67.0

60.0

54.5

49.2

45.6

42.3

39.4

27.5

28.9

«14

217

222

224

225

227

Continued at 40 mm

11. ....... .............. ..

12.............................

13.............................

14.................... ... ..

15....... -..L.. .................

200

225

250

275

300

392

437

482

527

572

4.4

7.3

7.4

8.2

8.3

21.0

49.8

57.1

64.5

70.7

79.0

100.0

0.841

.846

.854

.863

.875

.943

36.8

35.8

34.2

32.5

30.2

18.6

29

28

28

30

32

43

48

60

64

138

10

26

46

66

84

1 Saybolt Universal.

2 Calculated on basis of Bureau of Mines T. P. no. 610.

 Carbon residue of residuum, 11.7 percent; carbon residue of crude, 2.8 percent:

Approximate summary

Total gasoline and naphtha. . ........................

Medium lubricating distillate...... ...................

Viscous lubricating distillate......... .............

Distillation loss:... .................. ...... ..........

Percent

5.2

25.0

12.2

17.8

8.7

0

Spgr

0.662

0.734

0.807

0.837

O. 848-O. SOS

0.868-0.882

0 API

82.2

61.3

43.8

37.6

35. 4-31 . 5

31.5-28.9

Viscosity

Below 5O.

6O-1OO.

100-200.

Above 200.
GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 243

TABLE 11. Analyses of crude oil from the Tow Creek and Oak Creek fields, Routt

County, Colo. Continued

SAMPLE 40280

[Tow Creek field (south'pool); Nio'brara shale; 3;066 feet; sec. 18, T. 6 N., R. 86 

W. Analysis by U. S. Bureau of Mines, Bartlesville, Okla.[

Sp gr, 0.847

Sulfur, percent, 0.18

Saybolt Universal viscosity at 100°F, 43 sec.

API gravity, 35.6° 

Color, brownish-green

Distillation, Bureau of Mines Hempel method

Fraction no.

Cut at 

°C opPercent

Sum, 

percent

Spgr, 

60/60°F

API. 60°F

Correlation 

index

Viscosity,' 

100°F

Cloud

test, OF

At atmospheric pressure, 742 mm

[First drop, 33°C (91°F)

1.-..--.....- .-....-....-.-.

2..... .........................

3 - -.-...._....

4..............................

5... .. ............ . . . .

6... ...........................

7..... ......................

8.......... ....................

9..............................

10.... .........................

50

75

100

125

150

175

200

225

250

275

122

167

212

257

302

347

392

437

482

527

1.0

1.5

4.1

6.3

5.7

' 5.5

4.1

4.7

4.6

6.9

1.0

2.5

6.6

12.9

18.6

24.1

28.2

32.9

37.5

44.4

0.655

.678

.723

.747

.766

.785

.803

.819

.831

.839

84.5

77.2

64.2

57.9

53.2

48.8

44.7

41.3

38.8

37.2

11

23

25

27

29

31

33

33

32

Continued at 40 mm

11 .......................:... 12... ..........................

13...... . ............ ...... .

14............................

15 .-..... 

200

225

250

275

300

392

437

482

527

572

3.8

7.7

5.5

5.9

6.5

24.6

48.2

55.9

61.4

67.3

73.8

98.4

0.850

.856

.868

.878

.889

.946

35.0

33.8

31.5

29.7

27.7

18.1

34

33

35

37

39

40

46

58

85

150

10

30

50

70

85

1 Saybolt Universal.

3 Carbon residue of residuum, 4.5 percent; carbon residue of crude, 1.1 percent.

Approximate summary

Light gasoline. _ .. ______ . ....................

Total gasoline and naphtha.. __ ___ .. ... ... ...

Kerosene distillate.. .... _ _ ___ _ . .. ...

Gas oil........ .......................................

Nonviscous lubricating distillate .... ___ ..........

Medium lubricating distillate __ __ . __ . ...

Viscous lubricating distillate.... ____ . _ .. _ .

Distillation loss ......-........ __________ .

Percent

6.6

28.2

4.7

21.6

11.3

8.0

24.6

1.6

Spgr

0.702

0.756

0.819

0.845

0. 860-0. 880

0.880-0.895

O Q4R

"API

70.1

55.7

41.3

36.0

23. 0-29. 3

29. 3-26. 6

18.1

Viscosity

50-100.

100-200.

Above 200.
244 CONTRIBUTIONS TO ECONOMIC GEOLOGY

TABLE 11. Analyses of crude oil from the Tow Creek and Oak Creek fields, Routl 

' County, Colo. Continued

SAMPLE 40287

[Tow Creek field (south pool); Niobrara shale; 3,105 feet; sec. 17, T. 6 N., R. 

86 W. Analysis by U. S. Bureau of Mines, Bartlesville, Okla.]

Sp gr, 0.851 API gravity, 34.8° 

Sulfur, percent, 0.20 Color, brownish-green 

Saybolti.Universal viscosity at 100°F, 45 sec.

Distillation, Bureau of Mines Hempel method

Fraction no.

Cut at 

°C OF

Percent

Sum, 

percent

Spgr, 

60/60°F

API, 60°F

Correlation 

index

Viscosity, 1 

100°F

Cloud 

test,

op

At atmospheric pressure, 743 mm

[First drop, 33°C (91°F)]

1. .............................

2 - .-.... ......... _

3.. ... . 

4..............................

5... ...........................

6:........... ..................

7.. .......... ...... .........

8 ...........................

9..............................

10.............................

50

75

100

125

150

175

200

225

250

275

122

167

212

257

302

347

392

437

482

527

0.8

1.9

4.5

6.1

5

1

5.1

4.2

4.5

4.6

6.7

0.8

2.7

7.2

13.3

18.4

23.5

27.7

32.2

36.8

43.5

0.651

.678

.724

.748

.768

.788

.807

.821

.834

.842

85.9

77.2

63.9

",7 7

KO 7

48.1

43.8

40.9

38.2

36.6

11

23

26

27

30

33

34

35

34

Continued at 40 mm

11.. .....................-..

12............................

13.... __ .. _____ ..........

14.... ......................

15 ......... ..........

200

225

250

300

392

437

482

527

572

7.1

6.5

7.4

25.5

54.8

61.3

66.8

74.2

99.7

.856

.869

.880

.891

.949

35.0

33.8

31.3

29.3

27.3

17.6

33

36

38

40

46

59

87

155

30

50

70

85

'' Saybolt Universal. 

J Carbon residue of residuum, 4.9 percent; carbon residue of crude, 1.2 percent.

Approximate summary

Distillation loss. _______ - ___ 

Percent

7.2

27.7

4.5

21.2

11.9

8.9

25.5

0.3

Spgr

0.704

0.756

0.821

0.846

0. 860-0. 882

0. 882-0. 897

0.949

°API

69.5

55.7

40.9

35.8

33. 0-28. 9

28. 9-26. 3

17.6

Viscosity

50-100.

100-200.

Above 200.
GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 245

TABLE 11. Analyses of crude oil from the Tow Creek and Oak Creek fields, Routt

County, Colo. Continued

SAMPLE 40281

[Tow Creek field (north pool, abandoned); Niobrara shale; 3,485 feet; sec. 5, 

T. 6 N., R. 86 W. Analysis by U. S. Bureau of Mines, Bartlesville, Okla.]

Sp gr, 0.889 

Sulfur, percent, 0.32 

Saybolt Universal viscosity at 77°F, 

170 sec.; at 100°F, 97 sec.

API gravity, 27.7° 

Color, greenish-black

Distillation, Bureau of Mines Htmpel method

Fraction no.

Cut at 

°C °F

Percent

Sum, 

percent 60/60°F

API, 60°F

Correlation 

index

Viscosity, 1 

100°F

Cloud test, 

o F

At atmospheric pressure, 746 mm

[First drop, 59°C (138°F)]

1-..-.- ..-.-- ..-

2........................

3........................

4... _ ..................

5........................

6.... ....................

7........................

8........................

9........................

10.......................

50

75

100

125

150

175

200

225

250

275

122

167

212

257

302

347

392

437

482

527

1.1

2.6

1.6

2.2

3.8

3.1

4.1

4.3

6.0

1.1

3.7

5.3

7.5

11.3

14.4

18.5

22.8

28.8

0.697

.741

.761

.777

.797

.815

.832

.846

.857

71.5

59.5

54.4

50.6

46.0

42.1

38.6

35.8

33.6

31

32

32

34

37

39

41

41

Continued at 40 mm

11. .....................

12..... ............ ......

13.......................

15...... .................

200

225

250

275

300

392

437

482

572

2.7

7.2

6.9

6.0

8.3

39.2

31.5

38.7

45.6

59.9

99.1

0.867

.874

.887

.894

.904

.953

31.7

30.4

28.0

26.8

' 25.0

17.0

42

41

44

46

43

49

68

200

5.

30.

50.

70.

1 Saybolt Universal.

' Carbon residue of residuum, 5.8 percent; carbon residue of crude, 2.3 percent.

Gasoil . . . ....... ..1

Percent

3.7

14.4

21.1

11.1

9.1

4.2

39.2

.9

Sp Or

0.728

0.776

0.854

0. 875-0. 892

0. 892-0. 904

0. 904-0. 910

0.953

0 API

62.9

50.9

34 2

30. 2-27. 1

27. 1-25. 0

25. 0-24. 0

17.0

Viscosity

50-100. i nft-9nn
246 CONTRIBUTIONS TO ECONOMIC GEOLOGY

TABLE 11.- -Analyses of crude oil from the Tow Creek and Oak Creek fields, Routt 

County, Colo. Continued

SAMPLE 40288

[Tow Creek field (north pool, abandoned)j'Niobrara shale; 3,435 feet; sec. 5, 

T. 6 N., R. 86 W. Analysis by U. S. Bureau of Mines, Bartlesville, Okla.]

Sp gr, 0,896 

Sulfur, percent, 0.34 

Saybolt Universal viscosity at 100°F, 

105 sec.; at 130°F, 69 sec.

API gravity, 26-4° 

Color, greenish-black

Distillation, Bureau of Mines Hempel method

Fraction no.

Cut 

°C

at 

o F

Percent

Sum, 

percent

Spgr, 

60/60° F

API,

60° F

Correlation 

index

Viscosity,' 

100° F

Cloud test,

0 p

At atmospheric pressure, 745 mm

[First drop, 52°C(126°F)]

1. ................... .

2_____. _..___.._..__...__

3..... ...................

4........................

5................. ...... .

6........... ............ .

7....... .................

8........................

9........................

10...... .................

50

75

100

125

150

175

200

225

250

275

122

167

212

257

302

347

392

437

482

527

0.8

2.3

3.0

3.1

3.0

3.1

3.7

4.1

5.9

0.8

3.1

6.1

9.2

12.2

15.3

19 0

23.1

90 n

0.701

.735

.761

.783

.804

.822

.841

.856

.866

70.4

61.0

54.4

49.2

44.5

40.6

36.8

33.8

31.9

28

32

35

38

40

43

45

45

Continued at 40 mm

11-... ..................

12.......................

13............- ......

14....... _ .............

200

225

250

275

300

392

437

482

527

572

1.3

6.2

 6.4

6.7

41.0

30.3

36.5

49.6

99.5

0.875

.882

.891

.898

.908

.954

30.2

28.9

26.1

24.3

16.8

46

45

46

48

43

49

67

110

220

Do.

15.

30.

55.

1 Saybolt Universal.

' Carbon residue of residuum, 5.9 percent; carbon residue of crude, 2.4 percent.

Approximate summary

Light gasoline.... _____ .. ______________

Gas oil........................................ . ......

Distillation loss.... .......................... ........

Percent

3.1

18.5

11.0

41.0

.5

SpOr

0.726

0.862

0. 882-0. 896

0.954

°API

63.4

32.7

28. 9-26. 4

16.8

Viscosity

50-100.
GEOLOGY, MINERAL FUELS, ROUTT AND MOFFAT COUNTIES, COLO. 247

TABLE 11. Analyses of crude oil from the Tow Creek and Oak Creek fields, Routt

County, Colo. Continued

SAMPLE 40289

[Tow Creek field (north pool, abandoned); Niobrara shale; 3,635 feet; sec. 5, 

T. 6 N., R. 86 W. Analysis by U. S. Bureau of Mines, Bartlesville, Okla.]

Sp gr, 0.890 API gravity, 27.5° 

Sulfur, percent, 0.31 Color, greenish-black 

Saybolt Universal viscosity at 77°F, 165 sec.; at 100° 

F, 93 sec.

Distillation, Fureau of Mines Hempel method

Fraction no.

Cut at 

°C OF

Percent

Sum, 

percent

Spgr, 

60/60°F

API, 60°F

Correlation 

Index

Viscosity, 1 

100°F

Cloud test, OF

At atmospheric pressure, 745 mm

[First drop, 53°C (127°F)]

1-.. ................... -

2........................

3... ....... ..............

4...... ..................

5................... ..

6... .....................

7 

8................ . .

9........................

10 

50

75

100

125

150

175

200

225

250

275

122

167

212

257

302

347

392

437

482

527

0.5

1.9

3.0

3.1

3.5

3.4

4.1

4.3

5.8

0.5

2.4

5.4

8.5

12.0

15.4

19.5

23.8

29.6

0.696

.723

.752

.776

.797

.816

.834

.848

.858

71.8

64.2

56.7

50.9

46.0

41.9

38.2

35.4

33.4

23

27

31

34

37

40

41

41

Continued at 40 mm

11... ...............

12 

13 

14......... ..............

15 

200

225

250

275

300

392

437

482

527

572

2.8

6.4

6.4

7.5

8.8

38.3

32.4

38.8

45.2

52.7

61.5

99.8

0.867

.874

.885

.894

.905

.955

31.7

30.4

28.4

26.8

24'. 9

16.7

42

41

43

44

46

43

49

65

110

220

5.

25.

45.

70.

' Saybolt Universal.

8 Carbon residue of residuum, 6.2 percent; carbon residue of crude, 2.4 percent.

Approximate summary

Light gasoline- ..... ...... .... . ...............

Percent

2.4

15.4

20.6

11.4

8.3

5.8

38.3

0.2

Spgr

0.717

0.776

0.855

0. 875-0. 892

0. 892-0. 903

0. 903-0. 911

0.955

°API

65.9

50.9

34.6

30. 2-27. 1

27. 1-25. 2

25. 2-23. 8

16.7

Viscosity

50-100.

100-200.

INDEX

A . Page 

Agner. Mountain...-..-___......___... 147

Alluvium-----..------..----___.. 162

Analyses, coal---..------.__ 176,184r208

gas..--------.- ___-----_... 181

Oil.. 181,239-241,243-247

Anticlines.. - 169-170

Apex mine...... .... - 172

Arkose..--- ----..---__------ 180

Axial Basin anticline... - -.-- - 169

B 

Basalt boulders.......-...--.----..-.-.-- 162

flows- - - 163

Bear Elver.__.____.....___.___. 145

Bear River mine..... .. 157

Beaver Creek anticline. .. - 170,180,181 

Block mine coal bed.. .-... .. 165 

Boulder deposits..._ .__.__ . 162 

Breeze anticline.. - __ . 170,181 

Breeze Mountain....____.____.__.- 163

Browns Park formation('i')..........__.__._. 161-162

Buck Peak anticline.. - 170,181

Cheney Creek.. .-.__.______...__. 156 

Chimney Creek dome..-.--------- 151,169,179

Chinle formation....---...--.-....---- 180

Coal beds, faulting....... _._-.. 170

Fort Union;formatJoii.- ____ 161 

lies formation..__._____.___ 154-157 

Lance formation.----.. 160

Lewis shale ----------------------- 159-160

lower coal group- --. -- .-.-_... 171-173 

mapping...... -....- -------- 149

Mesaverde group . 152 

metamorphism..----. .-----..._...-.- 167

middle coal group...-_._______. 173-174 

occurrence_........-.---_...--_...- 147

thickness categories... ...... 177

upper coal group.....-. . . 174-175

Williams Fork formation.-.--.--..-. 158,159 

Coal, quality.----.----------- ---.- 175-176

reserves--.-.------------_ ..-._ 176-178

Coal View....-- .--- 145

Craig 145

Curtis formation...-.--..--..--.-....- 180

D 

Dakota sandstone ----------__ 178,179,180,181

D^atpn Peak..---..-.--- --------------- 163

Dikes.... - 163,164,171

Page 

Domes...... -- - ... . 169-170

Dry Creek....- ........ .............. 159

Dry Creek coal bed.....__________ 159,175. 

Dry Fork........--...-_...._ __ 175

E 

Edna strip mine___ __ ______ __ 173

Elkhead Creek-.--.-.-.--.......-...-..___ 146

Entrada sandstone..____________ 180,181

Faults .. 156,169,170,171

Fish Creek . 146, 156

Fish Creek anticline._____________ 154 

Flat Tops, basalt flows.---.--.------.-- 163

slide rock_ _______.. 162

Flows, basalt.-----.-.--._ ..._......... 163

Foidel Creek--- . 146

Folds ----------___..._......._..... 169

Fortification Creek....................__.. 146

Fort Union formation, coal beds_______ i75'

features.-_.-._____.___.___ 161 

Frontier sandstone.._____;__ 151,178,179,180

G

Gas. analyses.. ..-.- ________ 238 

fields. 147

occurrence . ..-.______ 178-181 

Grand Hogback..______.____.... 157 

Grassy Creek mine. - __._________ 173

H

Habro . . -__...----.-.- 145

Hamilton._.__...______________ 151

Harris mine.... .-.-. _______-.-. 173

Hart syncline___ __...______.- 170

Hayden.... . ._______._ 144 

Hayden mine__ _..-_.______. , 172

Hooker Mountain.._____._________ 163

lies formation. . ._ 152-157.pl. 16 

Inoceramus................................... 151

deformis.................................. 150

fragilis.................................... 150

sp........................................ 150

Intrusions . __.__.__ 164-169

Jim Dunn mine...._____._____J_ 174

249
250 INDEX

K Page 

Keystone mine.--__________-.- 172

Kimberly coal bed....-..-..---....----.._ 160,175

Lamprophyre.-_-----__.. _ . 163 

Lance formation, coal beds.------------- .. 175

features...-...--..---..-.-.-.-.-..--.--. 160-161 

Latite-trachyte. -- - - .- .-- 163 

Lennox coal bed_ _ - ------- 158,173

Lewis shale, features. --- -------- -._ 159-160

induration_ . 164 

Little Bear Creek-..-- - 175

Little Buck Mountain__ __ _ 147 

Long's Gulch__ . -. 155 

Lorella coal bed.________-______ 160,175 

Lower coal group . . 171-173

M 

Mancos shale... _ _ . - 150-152

McGregor .... 145 

Meeker___.___.____..__.-..-._ 157 

Mesaverde group. .-- 152-159

. Metamorphism.._. ... .. - -- 164-169 

Middle coal group_.._.-. _-- ' 173-174

' MiddleCreek- 146

Milner. _. __.._ . .____ 145

Mining, coal..... . . . 171-175

Moenkopi formation__..---. .- .. 180 

Morapos sandstone member. ... .. 151 

Morgan formation.....,.-... -... 180

Morrison formation__...... ------ ... 180

Mount Harris -----------__.- -- 145, pi. 17A

N

Newcastle.-.____-_.- . 157 

Niobrara formation.. . . 151

. IJlobrara shale_.. . 181

0

Oak Oreek........_..__.-.________ 145,146

Oak Creek oil pool.____.. .... ..178,180 

Oak Hills mine. - 172 

Oil, analyses.__--------__.__-_.-._ 168

eflect of intrusive bodies on. ... 166

fields.-.__-. --. -----.- ...... 147

occurrence....._..._.----...-..-... 178-181

Ostredcongesta................................ 151

Pagoda dome... 170,180

Pagoda gas pool.. . - --- -.- 147,178

Park Range.. . 146 

Phippsburg... . -- 145

Pilot Knob.....-.---.--.- _. . __ 146

', Pinnacle coalbed.-.-....- ......... . .... , 1,72

Pinnacle mine.._______ -----____ 172

 Pinnacle Movintaln_-..-.------.-------..-.. 147

PlUgS.... - 163

Q

Quaker Mountain.

R

Reserves, coal, anthracite_____.. __ 177 

bituminous ...... 209-223,232-233

calculation of ____. _______ 177 

Moflat County-------------._ 236

Routt County ------------------ 236-237

subbituminous---.-- -- 224-231, 234-235 

Rice (old Weber) mine 156,172

Rim Rocks._ 146,163

Sage Creek anticline..-____________ 154 

Sand deposits.__. ......................... 162

Sand Mountain..___-....___.___ 146,163

Scaphiles warreni............................. 151

Searcy Gulch bed...____.________ 174 

Shinarump conglomerate__________ 180,181 

Sills- - 163,164-167,169

Silt deposits__-________________ 162 

Slide rock......-._......................... 162

Steamboat Springs.-.. 146

Stratigraphic sections, lies formation.._.. 154-155 

Subbituminous coal, reserves___ 224-231,234-235 

Sugarloaf Mountain___..___.__.._. 147 

Sun (old Green) mine... . . 156,172 

Sundance formation......__..-..-.-..-.-.. 178

Synclines .. . 169-170

T 

Terraces... 162

Topography .............. .._. 146-147

Tow Creek anticline.....-. 154,169

Tow Creek gasfield.-.-.__ ............ 181

Tow Creek oilfield. . . 147,169,178 

Tow Creek sandstone member 152,155-156 

Trout Creek._ __________________ 146 

Trout Creek sandstone member.. 157,pi. 16B

Twentymile Park............................ 147

Twentyroile-Park synclme_- - 170

Twentymile sandstone member-...-... 158, pi. 17A

TJ 

TJnconsolidated deposits.--------..-.--------. 162

Upper coal group ... 174-175

w 

Wadge coalbed-.. 158,164,173

Wadge mine- -.. 164,173, pi. 17B 

Wasateh formation...---.--..-.-..-----.. 161 

Wasbakie structural .basin__________ 169

Weber sandstone.- -- _- - 180,181 

White mine--_-----___...___-_____ 175 

Williams Fork...... ...... ... 146

Williams Pork formation. 152-153,157-150. pi. 17 A 

Williams Fork Mountains___________ 147,153

Williams Park.... 147

Williams Park anticline. 170,179

Williams Park gasfleld_- - 147, 178,179, 181

Wolf Creek... MA

Wolf Creek coal bed__. __________ 158,165, 173 

Wolf'Creek dome.-.----- ----------------- 169, 179

Wolf Mountain . 146,163

147 Yampa River.

o

.145,146