GEOLOGICAL SURVEY CIRCULAR 53

August 1949

COAL RESOURCES OF MONTANA

By

John X. Combo, Donald M. Brown, Helen F. Puhrer

and Dorothy A. Taylor
UNITED STATES DEPARTMENT OF THE INTERIOR 

J. A. Krug, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

WASHINGTON, D. C.

Free on application to the Director. G«ologrical Survey. Washington 26. D. C.
COAL RESOURCES OF MONTANA

By

John X. Combo, Donald M. Brown 

Helm F. Pulver, and Dorothy A. Taylor

CONTENTS

Preface..............................

Introduction.........................

Montana coal fields..................

Fort Union region.i.............

Lignite area...............

Sub-bituminous coal area... 

Oarfleld County field...........

Bull Mountain field.............

North-cent ral region............

Great Falls and Lewistown 

fields...................

Area surrounding the Bearpaw Mountains............

Page

2

3

3

7

7

9

10

10

10

11

12

Page

Montana coal fields Continued.

Blackfeet-Valler area...... 12

Brldger and Sllvertlp fields.... 12

Stillwater field................ 13

Red Lodge field................. 13

Electric field.................. 14

Livingston-Trail Creek field.... 14

Lombard field................... 14

Flataead field.................. 14

Tertiary lake beds.............. 15

Montana coal -reserves................ 15

Selected bibliography................ 24

Index to 27

ILLUSTRATIONS

Page

Figure 1. Map of Montana showing coal-field areas....................................... 5

2. Generalized stratlgraphlc section of Cretaceous and Tertiary rocks and principal coal-bearing formations In the Montana coal fields...................... 6

3. Index map of eastern Montana and adjoining States showing location of coal 

fields In the Fort Union and nearby regions described In bulletins of the 

U.S. Geological Survey..................................................... 8

TABLES

Table 1. Estimated original bituminous coal reserves In Montana.....

2. Estimated original sub-bituminous coal reserves in Montana.

3. Estimated/ original .lignite reserves In Montana.............

4. Total estimated original coal reserves In Montana..........

5. Coal production In Montana during the years 1937-47........

Page

18

19

20

21

22
PREFAOB

nils report on the ooal resources of Montana Is the first of 

a series of State summary studies being undertaken by the Geological Survey as part of a program to reappraise the ooal reserves 

of the United States. The last estimate of ooal reserves In the 

Nation was made by M. R. Campbell of the Geological Survey In 19.28 

after a lifetime of work on tht geology and distribution of ooal. 

Mr. Campbell 1 a estimates have been extensively quoted and, with 

minor revisions, have been presented at times by the Geological 

Survey and other agencies. Since 1928, estimates of ooal reserves 

In several States and In Individual mining districts have been 

made by State Surveys, but for most States and for the Nation as 

a whole no comprehensive reappraisal has been attempted.

The Geological Survey has long been aware of the need for new 

and revised summary information about the Nation's ooal reserves, 

and during the last 20 years many detailed field surveys have been 

completed in anticipation of the opportunity of preparing new and 

more accurate reserve estimates. As the first step in the reappraisal of the coal reserves In the United States, this report 

presents a .new provisional estimate of original reserves in Montana, 

calculated by counties, by ranks of coal,, by classes of coal according to the reliability of the information on which the calculations were based, and by coal beds in different thickness groups. 

It is believed that this new estimate of Montana ooal reserves, 

which Is based on a careful and conservative analysis of the data 

available in the files of the Geological Survey, will have greater 

usefulness than earlier estimates.

WILLIAM B. WEATHER, 

Director.
INTRODUCTION

.The coal fields of Montana cover approximately 51,300 square miles, or 35 percent of the total area of the State. The 

coal ranges in rank from lignite to bituminous, and locally, as In the Electric and 

Great Palls fields, coal capable of producing 

nonferrous metallurgical coke occurs In small 

quantities. The coal fields are well distributed throughout most of the State, but 

the great concentration of reserves Is In 

the Great Plains region east of the Rocky 

Mountains, where the coal is of lignite and 

sub-bituminous rank.

The present report summarizes the results of a careful reappraisal of the coal 

reserves in Montana that was carried out as 

part of the Interior Department's program 

for the development of the Missouri River 

Basin. Like all estimates of coal reserves 

made in the present state of knowledge, it 

is provisional and subject to modifications 

and improvements. It does, however, provide 

a more accurate estimate of the coal reserves 

of Montana than has heretofore been available, and it presents the data more systematically and in greater detail than any 

previous estimate. Thus it furnishes a systematic framework to which additions and 

corrections can be made as other data are 

obtained.

According to the present, provisional 

estimate, the total original tonnage, before 

mining, of coal of all ranks in Montana is 

222,046,940,000 short tons. This amount is 

42 percent less than previous estimates, all 

of which are based on the work of M. R. 

Campbell in 1928. As quoted in an estimate 

published in 1943, Mr. Campbell reported an 

original tonnage of coal of all ranks in 

Montana of 381,114,000,000 tons.]./ The two 

estimates are not directly comparable, for 

as will be shown they are based on somewhat 

different assumptions. Nevertheless, it is 

noteworthy that a modern, conservative 

estimate of the total original reserves in 

Montana should so closely approach the 

earlier, more generous estimate.

In the present report, .the coal is 

classified according to the amount of metamorphism it has undergone. On this basis, 

every coal occupies a fixed position in a 

continuous natural series ranging from 

lignite to anthracite. This position is 

known as rank, as distinguished from grade 

or purity, of the coal. The classification 

used conforms to the standard specifications 

for classification of coals by rank of the 

American Society for Testing Materials 2/ as 

reproduced on page 4.

I/ Buch, J. W«, Hendrleka, T. A., and Toenges, 

A. L., Coal, in Mineral position of the United 

Statejs: Hearings before a subcommittee of the Committee on Public Lands, U. S. Senate, 80th Cong., 

1st seas., pp. 231-235, May 15, 16, and 20, 1%?.

2/ American Society for Testing Materials, 

Standard specifications for classification of coals 

by rank, ( A. S. T. M. Designation: D 388-38): 1939 

Book of A. S. T. M. Standards, pt. 3, pp. 1-6.

MONTANA COAL FIELDS

The Montana coal fields are in the 

Great Plains and Northern Rocky Mountain 

provinces. The Great Plains province includes the large Fort Union region and its 

subsidiaries, the Bull Mountain and Garfield 

County fields, and also the North-central 

region, which is composed of the Great Falls 

and Lewistown fields, the area surrounding 

the Bearpaw Mountains, and the BlackfeetValler area. The Northern Rocky Mountain 

province includes the Bridger, Silvertip, 

Stillwater, Red Lodge, Electric, LlvingstonTrail Creek, Lombard, and Flathead fields 

and the Tertiary lake-bed deposits in the 

southwestern part of the State. (See fig.l.)

The coal-bearing formations in Montana 

are of Cretaceous and Tertiary age. The 

Fort Union formation of Paleocene age contains more than 90 percent of the total 

coal reserves of the State and is the main 

coal-bearing formation in the Fort Union 

region, the Bull Mountain field, the Garfield County field, and the Red Lodge field. 

Other coal-bearing formations are the 

Kbotenai formation of Lower Cretaceous age; 

the Eagle sandstone and the Judith River and 

Hell Creek formations of Upper Cretaceous 

age; the Tullock formation of Paleocene age;, 

the Wasatch formation of Eocene age; and the 

Kishenehn (?) formation, made up of lake-bed 

deposits of Oligocene or Miocene age. The 

accompanying diagram (fig. 2.) shows a generalized stratigraphic section of coalbearing rocks in Montana and indicates the 

main producing formations in each field. 

Further discussion of the stratigraphy is 

contained in the descriptions of the several 

fields.

In the Great Plains province, in the 

eastern part of the State, the coal-bearing 

rocks, generally are flat lying or have been 

little disturbed, and the coal is low in 

rank. Near the North Dakota State line, 

for example, the coal is classed as lignite. 

In the Northern Rocky Mountain province, 

the coal-bearing rocks lie in basins between 

the mountain ranges and commonly exhibit 

gentle to moderate dips. The coal beds in 

these rocks range in rank from subbituminous to bituminous. The Tertiary lake 

beds, which are in small basins in the 

mountain valleys of the southwestern part of 

the State, are relatively so young that 

metamorphism of the coal has not progressed 

beyond the rank of lignite.

Although details of the geology and 

coal deposits of much of Montana are imperfectly known, large areas have been 

mapped and described In the Geological 

Survey bulletins that are listed and indexed 

in the selected bibliography on pages 24-26. 

In addition, analyses of coal from many 

parts of the State have been made by the 

Bureau of Mines ,3_/ Unless otherwise stated, 

the Information contained in the following 

paragraphs describing the various fields 

has been abstracted from these publications.

2/ Analyaes of Montana coals, U. S. Bur. 

Mines Tech. Paper 529, 1932.
Legend: F.C. - Fixed Carbon.

CLASSIFICATION OF COALS BY RANK.0 

V.M. - Volatile Matter. Btu. British thermal units.

Class Group

Limits of Fixed'Carbon or

Btu. Mineral-Matter-Free

Basis

Requisite Physical 

Properties

I. Anthracitic

1. Meta-anthracite.

2. Anthracite......

Dry S3~" F.C.. 98 per cent or more

'

V.M., 2 per cent or

3. Semianthracite.

Dry F.C., 92 per cent or more 

and. less than 98 per cent 

(Dry V.M., 8 per cent or less 

and more than 2 per cent)

Dry F.C., 86 per cent or more 

and less than 92 per cent 

(Dry V.M., 14 per cent or 

less and more than 8 per 

cent)

Nonagglomerating*

II. Bituminous**

1. Low volatile bituminous coal....

2. Medium volatile bituminous coal;

3. High volatile A bituminous coal.

4. High volatile B bituminous coal. 

"5. High volatile C bituminous coal.

Dry F.C., 78 per cent or more 

and less than 86 per cent 

(Dry V.M., 22 per cent or 

less and more than 14 per 

cent)

Dry F.C., 69 per cent or more 

and less than 78 per cent 

(Dry V.M., 31 per cent or 

less and more than 22 per 

cent)

Dry F.C., less than 69 per cent 

(Dry V.M., more than 31 per 

cent); and moistc Btu., 

14,000* or more

Moist" Btu., 13,000 or more 

and less than 14,000*

Moist Btu., 11,000 or more 

and less than 13,000*

Either agglomerating or 

nonweatheringS

III. Subbitumihous

1. Subbituminous A coal.

2. Subbituminous B coal.

3. Subbituminous C coal.

Moist Btu., 11,000 or more 

and less than 13,000*

Moist Btu., 9500 or more and 

less than 11,000*

Moist Btu., 8300 or more and 

less than 9500*

Both weathering and 

nonagglomerating

IV. Lignitic 1. Lignite.....

2. Brown coal.

Moist Btu., less than 8300 

Moist Btu., less than 8300

Consolidated 

Unconsolidated

a This classification does not include a few coals which have unusual physical and chemical properties and which come 

within the limits of fixed carbon or Btu. of the high-volatile bituminous and Subbituminous ranks. All of these coals 

either contain less than 48 per cent dry, mineral-matter-free fixed carbon or have more than 15,500 moist, mineral-matterfree Btu.

b If agglomerating, classify in low-volatile group of the bituminous class.

c Moist Btu. refers to coal containing its natural bed moisture but not including visible water on the surface of the 

coaL

d It is recognized that there may be noncaking varieties in each group of the bituminous class.

9 Coals having 69 per cent or more fixed carbon on the dry, mineral-matter-free basis shall be classified according to 

fixed carbon, regardless of Btu.

f There are three varieties of coal in the high-volatile C hUuminous coal group, namely, Variety 1, agglomerating 

and nonweathering; Variety 2, agglomerating and weathering; Variety 3, nonagglomerating and nonweathering.
Known occurrence of lignite 

in Tertiorv loke bed*

FIGURE I.MAP OF MONTANA SHOWING COALFIELD AREAS
Figure 2. Generalized strati graphic section of Cretaceous and Tertiary rocks and principal coal-bearing 

/~"X*Main coal-bearing formation in field; x*Minor coal-bearing formation in f

Era 

and 

Period

o

M 

O 

M 

0

!B 

W

0

o

M 

O 

N 

O

m

w

S3

*» 

b

Hi 

«rl 

4J 

fc 

0> 

E<

' n

3 

o

Q> 

O 

0» 

4J 

ID 

b 

O

Series

Miocene 

or 

Oligocene

Eocene

Paleocene

Upper

Lower

Group,

formation, 

and 

member

Kishenehn (?) 

formation

Vfasatch formation

Fort 

Union

formation

Tongue 

River 

member

Lebo shale 

member

Tullock formation*

Hell Creek 

formation

.Montana group

Lem 

stoi 

Hil]

lep sandle (Fox

.s) /

Bearpaw shale

Judith River 

formation

Claggett 

shale

Eagle sandstone

Telegraph Creek 

formation

Colorado 

shale

Eootenai 

formation

Range 

of 

thickness 

(in 

feet)

1,500 

to

3,000

0 to 

472/

1,000 

to. 

1,500

150 to 

160

450 to 

950

2i5&°

250 to 

1,100

425 to 

600

500 to 

850

135 to 

250

0 to 

350

1,500 

to

2,500

220 to 

2,500

Lithology

Fresh-water lake 

deposits

Variegated sand 

and clay

Light-gray to tan 

sandstone, massive 

and thin-bedded

Light- to darkcolored shale, interbedded sandatone

Yellowish sandstone 

and jjh&le

Alternating sandstone 

and clay

Buff to brown sandstone

Dark marine shale

Qrayish-white sandstone 

and light- to dark- 

_ colored shale

Dark marine shale

Buff sandstone

Yellow and sandy shale 

and sandstone

Dark-gray to black 

shale with occasional sandy zone

Gray sandstone and 

shale with red shale

Region or 

ti 

o

3 *§

-P Ti

ft tO 

O <D

h fc

X

X

X

X

X

 a

H 

ID !>> 

ri -P "d 

<fH C rH

h d ID 

0» 0-H 

CJOVi

X

X

X

i

Bull Mountain 

field

X

X

X

*

Great Falls

and Lewistown 

fields

X

Area surround ing the Bearpaw Mountains

t

X

X

BlaokfeetValier 

area

1/x

S/I

£3

h 

o 

W)-

 O -

 ri 

tl 

n 

X

\J St. Mary River formation. Z/ Upper part of the Two Medicine formati
Fort Union region

The Port Union region includes most of 

eastern Montana and contains the greater 

part of the coal reserves. Most of the coal 

in this region occurs in the Port Union 

formation of Paleocene age, but a few thin 

beds are present also in the basal part of 

the overlying Wasatch formation, in the 

underlying Tullock formation, and near the 

top of the Hell Creek formation. The Port 

Union formation consists of alternating beds 

of sandstone, shale, and coal approximately 

1,500 feet thick. The formation is divided 

on the basis of lithologic differences into 

an upper, or Tongue River, member, consisting 

mainly of sandstone, and a lower member, the 

Lebo shale. Near the North Dakota border 

the Lebo shale member is not recognized, and 

rocks occurring at the same stratigraphic 

position are known as the Ludlow formation. 

The Tongue River member, which is the chief 

coal-bearing member of the Port Union formation, is about 1,100 feet thick in the 

eastern part of the State and tends to 

become progressively thicker to the west and 

south. This increase ia accompanied by an 

increase in the number and thickness of the 

coal beds. In the western and southern parts 

of the region, for example, as many as 20 

coal beds- are present, some of which are as 

much as 40 feet thick.

Coal deposits underlie the entire Fort 

Union region, but the beds generally are 

discontinuous, and they may vary greatly in 

thickness, so that correlations of individual 

beds between fields are difficult to establish. This is particularly true in the 

northeastern and north-central part of the 

State where the cover of- glacial drift has 

obscured most of the natural outcrops.

The rank of the coal in the Port Union 

region increases progressively westward from 

lignite near the North Dakota State line to 

sub-bituminous C coal west of Miles City and 

sub-bituminous B farther west in southern 

Rosebud and eastern Big Horn Counties. This 

change is very gradual, and the rate of 

change varies somewhat in different beds. 

Because of this gradual change and because 

of the precise analytical data necessary to 

classify coals by rank,4_/ many more analyses 

than are available at present would be required to establish the exact position of 

the boundary between lignite and subbituminous coal. The line on the accompanying map (fig. 1), however, shows the approximate position based on available 

analyses, of this boundary. It should be 

noted that although the coal near the North 

Dakota State line may have heat values of 

less than 7,000 B. t. u. on the as-received 

basis and coal from the area around Colstrip, 

Rosebud County, may contain more than 9,000 

B. t. u. on the same basis, there is little 

significant difference between coal of the 

two ranks near the boundary line.

IjJ American Society tor Testing Materials, 

Standard specifications for classification of coals 

by rank, (A. S. T. M. Designation: D 383-38): 1939 

Book of A. S. T. M. Standards, pt. 3, pp. 1-6.

As the heat value of the coal increases 

westward, the moisture content decreases. 

The lignite in eastern Montana, for example, 

has a maximum moisture content of 43 percent, 

whereas farther west near Colstrip the coal 

has a moisture content of only about 25 percent. The percentage of impurities shows 

much less variation. Throughout the Port 

Union region the ash content of the coal 

ranges from 5 to 10 percent and the sulfur 

content from 0.3 to 1.7 percent. It should 

be noted, however, that most of the analyses 

show sulfur contents ranging typically from 

0.5 to 1,0 percent.

The coal in the Port Union region tends 

to burn spontaneously when exposed to the 

atmosphere. In the southern part of the 

region, where no protecting cover of glacial 

drift was deposited and where the coalbearing rocka are dissected, burned and 

clinkered outcrops are a characteristic 

feature. Some of the higher beds in this 

part of the region have been almost completely destroyed by burning.

As the Fort Union region is large and 

the coal beds and stratigraphy of the coalbearing rocks vary in different parts of the 

region, it is divided for the purpose of 

discussion into two areas an eastern, 

lignite-bearing area and a western, subbituminous coal bearing area as previously 

defined.

Lignite area. The lignite-bearing area 

of the Port Union region is made up of the 

following fields, named from nearby towns or 

well-known localities and described for the 

most part in Geological Survey bulletins 

under titles bearing the same names: the 

Ekalaka, Baker, Terry, Glendlve, Mizpah, 

Sidney, Richey-Lambert, McCone County, Port 

Peck Indian Reservation, Scobey, and Culbertson fields and the eastern parts of the 

Miles City and Little Sheep Mountain fields. 

(See fig. 3.)

Most of the coal in the lignite-bearing 

area of the Port Union region is contained 

in the Tongue River member of the Port Union 

formation; subordinate amounts- are present, 

however, in the Lebo shale member of the Port 

Union and in both the Tullock and Hell Creek 

formations. The Tongue River member is 1,000 

to 1,500 feet thick throughout most of the 

lignite-bearing area and is composed primarily of light-gray to tan sandstone, massive 

and thin-bedded, containing interbedded 

shale and coal. Many of the coal beds in the 

Tongue River member are relatively free from 

partings and are thick and continuous over 

large areas. In the Glendive field, in 

Dawson and Wibaux Counties, a bed 4 feet or 

more thick is known to be generally present 

for a distance of more than 150 miles along 

the outcrop. In the Sidney field, in east 

Dawson, north Wibaux, and south Richland 

Counties, bed H is recorded as being continuous, with an average thickness of 4.7 feet 

over long distances. Besides these and other 

thick beds, there are many thinner, less 

persistent seams in both the Glendlve and 

Sidney fields. In the northern Scobey and 

Culbertson fields, in Daniels and Sheridan 

Counties, the beds are somewhat thinner, and 

less is known about the continuity of the
Figure 3. Index map of eastern Montana and adjoining States showing loca UJ.on of 

in the Port Union and nearby regions described in bulletins of the U.S. Geologi
outcrops. This is due partly to difficulty 

in tracing outcrops because of the concealing 

cover of glacial" drift.

'In the western part of the lignitebearing area, in the Miles City and Little 

Sheep Mountain fields, the beds generally 

are discontinuous, and many are 'thin or 

contain too many partings to be mined profitably, These fields are in the transitional 

belt between the lignite-bearing area and 

the sub-bituminous coal bearing area. 

Locally the upper beds in the transitional 

belt are more lignitio than the lower ones.

The lignite-bearing part of the Fort 

Union region contains many small wagon mines, 

most of which are abandoned as soon as 

mining has progressed a short distance from 

the outcrop* A modest total production for 

looal use is obtained from these -mlnea each 

year (see table 5), but because of the 

difficulty of shipping and storing lignite , 

no large-soale mining operations are carried 

on.

Sub-bituminous coal area. The subbituminous coal bearing part of the Port 

Union region includes the Forsyth, Rosebud, 

Ashland,Sheridan (northward extension), 

Pullook Creek, Crow Indian Reservation, 

Urney-Broadus, and Moorhead fields and the 

western parts of the Miles City and Little 

Sheep Mountain fields. (See fig. 3.)

As in the eastern part of the Fort Union 

region, the Tongue River member of the Fort 

Jnion formation contains most of the coal in 

the sub-bituminous coal bearing area* Where' 

the complete section of the formation is 

exposed in this area, it ranges from about 

1,500 to 1,700 feet In thickness and may 

contain as many as 20 coal beds.

The Forsyth field, in central Rosebud 

County, contains several thick persistent 

beds of coal relatively free from partings. 

The most valuable of these is the Rosebud 

bed, which is mined by the Northwestern 

Improvement Co. at Colstrip, where the bed is 

485 feet above the base of the Tongue River 

member of the Fort Union formation and 

averages 28 feet in thickness. The coal is 

mined on a large scale by stripping approximately 50 feet of overburden of weathered 

sandstone and alluvium. A representative 

sample of coal from the Rosebud bed at this 

mine, analyzed on the as-received basis, had 

a heat value of 9,090 B. t. u., with ash and 

sulfur contents of 7.3 and 0.7 percent, respectively. Another valuable bed ,in the 

field is the Burley bed, 130 feet above the 

base of the Tongue River member, which 

averages about 3 feet in thickness in the 

west-central part of the field.

In the Rosebud field, in Rosebud and 

Ouster Counties, the Burley bed, which is 

correlated with the bed of that name in the 

Forsyth and Ashland fields, contains the 

most*coal. The Burley bed has a thickness 

range of 2 inches to 8.5 feet in the Rosebud 

field and contains clean coal of good 

quality. The Rosebud bed, which also is 

present in this field, attains a thickness of 

more than 20 feet but crops out over a 

smaller area than the Burley bed and has been 

rembved in part by burning.

The Ashland coal field, in parts of 

Ouster, Rosebud, and Powder River Counties, 

is south of the Rosebud field and east of the 

Forsyth field. Many townships in this field 

contain five to eight coal beds with average 

thicknesses of more than 6 feet, and outcrop's 

of coal beds 10 feet thick are common. Beds 

20 to 25 feet thick occur in several localities and are continuous, as well as consistent in thickness throughout areas of 

several square miles. In general, the coal 

beds are remarkably free from partings. 

Cropping out along the Tongue River, which 

cuts across the center of the field, are the 

Knoblook bed, 300 feet above the base of the 

Tongue River member of the Fort Union formation} the Sawyer bed, 600 feet above the 

base; and the 8 bed, 875 feet above the base* 

These intervals decrease eastward as the 

lower half of the Tongue River member becomes 

thinner.

In the northward extension of the 

Sheridan field, which is south of the Ashland 

field, the Anderson bed attains a maximum 

thickness of 25 feet and in several places is 

measured as 20 feet thick. Bxcept where 

burned at the outcrop, this is the thickest 

and most persistent bed in the field. The 

Diets bed is commercially valuable in the 

southern half of the field, where it averages 

between 8 and 12 feet in thickness. Other 

thick beds are the Canyon and the Wall.

The Tullock Creek coal field is in 

southern Treasure and northern Big Horn 

Counties east of the Junction of the Big Horn 

and Yellowstone Rivers. Most of the coal in 

this field is contained in the Tongue River 

member of the Fort Union formation, but 

subordinate amounts are present in the 

Tullock formation. The coal in the Tongue 

River member occurs in six beds ranging from 

1 foot to 24 feet in thickness. In the four 

thickest beds, designated M, P, Q, and R in 

published reports, the coal is in thick 

benches unbroken by partings. All the beds, 

however, are commonly burned at the outcrops. 

Coal beds more than 18 inches but less than 

5 feet thick are present locally at 10 

horizons in the Tullock formation. The 

Tullock Creek field is undeveloped except for 

small wagon mines.

In the eastern part of the Crow Indian 

Reservation field, in Big Horn County, as in 

the Tullock Creek field, most of the coal is 

in the Tongue River member of the Fort Union 

formation. About 20 beds of minable thickness have been mapped in this area, and some 

of great lateral extent have been tentatively correlated with beds farthe-r east in 

the northward extension of the Sheridan coal 

field. Coal occurs also in the Cloverly, 

Parkman, Bearpaw, Hell Creek, Tullock, and 

Wasatch formations in the Crow Indian Reservation field, but the beds are of small 

extent and are generally too thin and impure 

to be of commercial value.

The Birney-Broadus and Moorhead fields, 

lying predominantly in Powder River County 

in the southeastern part of the State, contain many thick continuous coal beds, and 

the- concentration of coal in these areas is 

greater than in any other part of Montana. 

Detailed surveys of these fields have 

recently been completed by the Geological
Survey, and preparation of maps showing the 

position of the coal beds and correlations 

with beds in adjoining fields is now in 

progress. The calculation of coal reserves 

in these areas has been completed, however, 

and the results, as shown in the accompanying 

tables, give Powder River County 19.5 percent 

of the total reserves of the State as compared to 19.6 percent for Big Horn Cpunty and 

17.5 percent for Rosebud County. It is 

clear, therefore, that most of the coal in 

Montana is concentrated in the southern part 

of the Port Union region.

Qarfield County field

The Qarfield County field is west of the 

Port Union region. Most of the coal in this 

field occurs in the Hell Creek formation of 

Upper Cretaceous age and in the Tullook formation of Tertiary (Paleocene) age. In the 

southern part of the field, a small amount of 

coal is present in the Tongue River member of 

the Port Union formation. The ooal is of 

sub-bituminous 0 rank over the greater part 

of the field 'and, as compared to that in 

other fields in eastern Montana, is thin and 

relatively unimportant.

In the northern part of the field, 

minable coal occurs in two beds. Bed A, 

which is 40 to 90 feet below the top of the 

Hell Creek formation, averages about 4.5 feet 

in thickness and contains the best coal,in 

the field. Bed B, at the base of the overlying Tullock formation ia generally thinner, 

softer, and higher in ash than bed A. In 

the southern part of the field, no minable 

coal is present in the Hell Creek and Tullock 

formations. There is a coal bed, however, at 

the base of the Tongue River member of the 

Port Union. This bed is very thin, ranging 

from a few inches to 30 inches in thickness.

The beds in the Garfield County field, 

as in the Port Union region, are nearly flat 

lying. The axis of the Blood Creek syncline 

trends eastward through the center of Qarfield County, and the beds on either side dip 

toward it at angles of less than 1°.

Bull Mountain field

The Bull Mountain field is mainly in 

Musselshell and Yellowstone Counties but 

extends into Golden Valley, Stillwater, 

Treasure, and Rosebud Counties. (See fig. Ij 

The coal-bearing rocks in the field are the 

Tongue River member of the Port Union formation and, to a lesser extent, the underlying Lebo shale member and the Tullock formation. The coal is of sub-bituminous B and 

sub-bituminous A ranks.

The Tongue River member of the Port 

Union, which is the main coal-bearing unit in 

the field, is about 1,700 feet thick and contains 26 persistent coal beds in addition to 

many thin and lenticular beds. Most of the 

commercial mining is in the Roundup bed, 

 which crops out in the northern and northwestern part of the field. In the vicinity 

of Roundup this bed is 500 feet above the 

base of the Tongue River member and ranges 

in thickness from 4 to 6 feet. This thickness decreases to the east, gradually at 

first and then sharply, until at a point 

about 12 miles from Roundup it measures 

only 1.6 feet. A representative analysis, 

on the as-received basis, of coal taken from 

this bed shows a heat value of 11,000 

B. t. u. and ash and sulfur contents of 7.5 

and 0.4 percent, respectively. The Carpenter 

Creek bed, which is about 50 feet below the 

Roundup bed, is commercially important in the 

northeastern part of the field, where it 

ranges in thickness from 4 to 8 feet. An 

analysis of a typical sample of coal from 

this bed, on the as-received basis, shows 

a heat value of 10,170 B. t. u. and ash and 

sulfur contents of 4.3 and 1.3 percent, 

respectively.

Coal was actively mined from these beds 

in 1940 by the Bair Colllns Co., the Jeffries 

Coal Mining Co., the Republic Coal Co., and - 

the Roundup Coal Mining Co.

The Lebo shale member of the Port Union 

formation contains, for the most part, only 

carbonaceous shale in the Bull Mountain 

field. The Big Dirty coal bed, which occurs 

near the middle of the member, ranges in 

thickness from 2 to 24 feet, but although it 

is a prominent marker in the field, it contains only 2 inches to 1 foot of clean ooal. 

Economically this bed is unimportant. Most 

of the beds in the Tullock formation are 

thin, and only one, the Homestead, is of 

minable thickness. In a prospect in T. 10 If., 

R. 27 E., the total thickness of coal in the 

Homestead bed is 2.9 feet. An analysis of 

coal from this bed, on the as-received basis, 

shows a heat value of 10,420 B. t. u. and ash 

and sulfur contents of 4.2 and 0.9 percent, 

respectively.

Most of the central part of the Bull 

Mountain field is a broad, shallow synclinal 

basin, the axis of which trends generally 

northwestward. The beds dip gently at angles 

of 1° to 5° toward the center of the basin 

but are flatter to the east and south of the 

axis and steeper.to the north. Most of the 

coal in the Bull Mountain field is in this 

broad central part of the basin where the 

rocks are undisturbed and the dips are low. 

Toward the northwest the dips steepen to as . 

much as 30°, and the coal-bearing rocks form 

two sharply accentuated, northwest-trending 

synclinal folds, separated by an equally 

sharp anticlinal fold from which the coalbearing rocks have been removed by erosion.

North-central region

The North-central region includes all 

the coal-bearing lands in the north-central 

part of the State. For discussion in this 

paper, this region has been subdivided into 

three parts: in the south, the Great Falls, 

and Lewistown fields; in the north and east, 

an area surrounding the Bearpaw Mountains; 

and in the west, the Blackfeet-Valier area, 

which is separated from the main part of the 

North-central region by the Sweetgrass arch, 

a prominant structural feature that trends 

southward through Toole, Pondera, and Teton 

Counties. The coal in the North-central 

region ranges in age from Lower Cretaceous 

through Tertiary (Paleocene) and, in rank,

10
from bituminous to sub-bituminous. In contrast to the Port Union region in the 

eastern part of ftontana, where a great proportion of the land is underlain by minable 

coal/ the North-central region contains only 

scattered areas where coal of minable thickness has been found.

Great Falls and Lewiatown fields.- The 

Great Falls and Lewistown fields are located 

in Cascade, Judith Basin, and Fergus 

Counties. The Great Falls field extends east 

from the Missouri River near Oreat Falls for 

a distance of 60 miles along the base of the 

Little Belt Mountains to a point east of 

Stanford where it merges with the Lewiatown 

field in Judith Basin and Fergus Counties* 

The two fields are continuous, and both contain ooal in the Kootenai formation of Lower 

Cretaceous age. The coal occurs in a zone 

about 60 to 90 feet above the base of the 

formation and is of high volatile B and C 

bituminous rank. The roofs of the mines In 

these two fields usually consist of 1 foot 

or 2 feet of dark shale overlain by 60 feet 

of massive gray sandstone, which serves as a 

distinctive marker for the ooal horizon. 

Below the ooal are soft greenish shales.

In the Great Falls field, the Kootenai 

formation has a thickness of 475 feet and 

consists mainly of alternating beds of sandstone and shale. The ooal does not occur In 

a continuous horizon of workable ooal but Is 

found In three basins of deposition called 

the Sand Coulee, Otter Creek, and Sage Creek 

districts, which together cover a minimum 

area of 334 square miles.

The Sand Coulee district is by far the 

largest and most Important of the three. It 

is directly south of Great Falls and includes 

the area drained by the Sand Coulee and Its 

tributaries. At the town of Belt, in the 

northeastern part of the district, the 

average total thickness of the coal is 4.6 

feet, whereas at Sand Coulee the average 

total thickness is 8.6 feet and along Smith 

River it is 7.5 feet. At Belt Creek the coal 

is in three benches, the lower and upper of 

which are about equal in thickness and much 

thicker than the middle one. In Sand Coulee 

the coal is in two blenches, the upper one of 

which is much thicker than the lower. 

Above the top bench at Sand Coulee, however, 

are two higher beds of coal with a maximum 

total thickness of 5.7 feet. At Smith River 

the coal beds are similar in thickness and 

distribution to those near Sand Coulee.

The Otter Creek district is about 45 

miles east of Great Falls, extending along 

both sides of Otter Creek for a distance of 

about 10 miles. Only one coal bed, which 

ranges from 3 to 6 feet in total thickness, 

is present in the district. Generally the 

coal in this bed is separated by a bony 

parting into two benches, the lower of which 

is usually the thicker and has the betterquality coal. On the whole, the coal bed is 

thickest in the center of the district and 

thins to the sides.

The Sage Creek district, which is in. 

the eastern part of the Great Falls field a 

few miles south of Stanford, contains only

one coal bed, which ranges in total thickness, including partings, from 6 to 18 feet. 

The total thickness of coal present in this 

bed ranges from 2.5 feet to 7 feet and 

usually occurs in three benches. The lowest 

bench is 2 feet thick and is regarded as the 

best.

A typical sample of coal from this 

field, analyzed on the as-received basis, 

shows a heat value of 10,120 B. t. u. and 

ash and sulfur contents of 18.1 and 1.7 

percent, respectively.

Certain benches of the ooal possess 

coking properties, and the Anaconda Mining 

Co. formerly operated ooke ovens at Belt. 

The ovens were abandoned, however, because 

of the difficulty and expense of separating 

coking from nonooklng ooal.

The rooks In the Great Falls field dip 

gently northward away from the little Belt 

Mountains at angles of 3° to 5°, except in a 

narrow area at the foot of the mountains 

where dips may be as much as 10° or 15°. 

Low undulations interrupt the regional dip, 

and minor faults with displacements of 5 'to 

20 feet are present throughout the field. A 

few basalt dikes that do not cut the ooal 

beds have also been observed. None of these 

features has caused more than slight Inconvenience In mining.

The Lewistown field extends southwest 

from the vicinity of Lewistown along the 

north slopes of the Big Snowy and Little 

Belt Mountains and joins the Great Falls 

field. The Kootenai formation, which contains the coal in the Lewistown field, 

averages 500 feet in thickness in the vicinity of Lewistown as compared to 475 feet 

in the Great Falls field. The coal beds in 

the Lewistown field are not continuous but 

are broken by nonproductive zones of carbonaceous shale. The most important of the 

productive areas are the Buffalo Creek district, on the north slope of the Little Belt 

Mountains; the Rock Creek district, on the 

north slope of the Big Snowy Mountalna; the 

Lewistown district, on Big Spring Creek north 

of Lewistown; and the MacDonald Creek' district, on the east edge of the field south of 

the Judith Mountains. The MacDonald Creek 

district is the largest and best developed 

in the Lewistown field.

Where coal is mined in the Lewis-town 

field, the beds range in thickness from 2,5 

feet to 8 feet and usually occur in two or 

more benches, with partings of bone and 

shale, as in the Great Falls field. The 

coals of the two fields are very similar in 

composition except that in the Lewistown 

field the ash content is lower, averaging 

about 8 percent, whereas the relatively higb 

sulfur content averages over 4 percent.

The structure is simple in that part 

of the Lewistown field adjoining the Great 

Falls field, where the beds dip to the north 

at low angles away from the Little Belt and 

Big Snowy Mountains. Farther east, the beds 

are arched and faulted locally and are 

intruded by laccoliths associated with the 

Judith and Moccasin Mountains.

11
Area surrounding the Bearpaw Mountains . North of. the great Falls and Lew!stown fields is an area of approximately 

10,5QO square miles underlain by essentially 

flat-lying, ooal-bearing rooks. It includes 

all of Hill County and parts of Tools, 

Liberty, Ohouteau, Fergus, and Blaine 

Counties. Because of the cover of glacial 

drift, which extends over most of this area, 

determination of the extent of coal beds has 

been difficult. Coal occurs in the Eagle 

sandstone and Judith River formation of 

Upper Cretaceous age and locally in the Fort 

Union formation of Tertiary (Faleooene) age. 

Coal of sub-bituminous A and B ranks and 

locally, near intrusives, of high volatile 

0 and B bituminous ranks occurs sporadically 

throughout the area. In most places, however, the coal is too thin and lenticular to 

allow commercial operations.

In northern Ohouteau County, at the Big 

Sandy mine, coal of sub-bituminous rank 

occurs in minable thicknesses in a small, 

downfaulted area that has preserved beds of 

Fort Union age. Other thin, lenticular coal 

beds are present in the Judith River formation and the Eagle sandstone.

The Milk River field, which is farther 

north In Hill and Blaine Counties, contains 

coal of sub-bituminous rank In the upper 

part of the Judith River formation. Mining 

has been carried on in this field at Havre 

and Chinook on the Great Northern Railroad, 

both of which supply small, local demands 

for fuel. The coal "bed at Havre, in Hill 

County, ranges from 2.5 to 6.7 feet in thickness, but much of the bed is Impure and contains .partings of bone and shale. At 

Chinook, to the east in -Blaine County, the 

coal is of essentially the same thickness 

and character.

Farther west, in western Hill and 

eastern Liberty Counties, the Judith River 

formation contains coal in thin, lenticular 

beds in a zone about 200 feet from the base 

of the formation. The thickness of these 

beds is generally about 1 foot to 1.5 feet, 

although locally it exceeds 5 feet.

In northwest Liberty and northeast 

Toole Counties, analyses show the coal to be 

locally of high volatile B bituminous rank. 

This is probably due to alteration of the 

beds by igneous intrusions in this part of 

the field. No beds of minable thickness 

have been mapped here.

Except for a few minor undulations, the 

rocks in the area surrounding the Bearpaw 

Mountains dip gently northeastward to eastward from the crest of the Sweetgrass arch. 

Several thrust faults, together with a few 

intrusive igneous masses, break the continuity of the beds, but in areas where 

mining has been carried on these have caused 

little difficulty.

Blaokfeet-Valier .area. The BlackfeetValier area begins in Cascade County approximately 30 miles south of Chouteau and 

extends north in a belt 6 to 16 miles wide 

through Teton, Pondera, and Glacier Counties 

to the Canadian border. The name has been

taken from two small fields that are in 

Fondera and Glacier Counties. The coal in 

the Blaokfeet-Valier area occurs in the Two 

Medicine and St. Mary River formations of 

Upper Cretaceous age* The Two Medicine formation is correlated with the Olaggett and 

Judith River formations of eastern and central Montana, and the St. Mary River formation is correlated with the Hell Creek and 

Tullook formations. The coal in the Blaokfeet-Valier area occurs at five horizons, 

three in the Two Medicine formation and two 

in the St. Mary River formation, but throughout most of the area it is thin, bony, and 

sporadic in distribution. On the basis of 

available analyses, the ooal is of high 

volatile C and B bituminous ranks.

Ooal has been mined to the greatest 

extent from the Valier field in Fondera 

County where the beds are nearly flat lying. 

There, clean ooal about 20 inches thick, 

including a 2-inoh parting, has been taken 

from the upper bed of the Two Medicine formation. The Blackfeet field, to the northwest in the Blaokfeet Indian Reservation in 

Glaoier County contains minable coal at the 

base of the St. Mary River formation. Very 

little mining has been done in this field 

because steeply dipping strata, together 

with thrust faults, carry the coal below 

minable depths within short distances from 

the outcrops. Clean coal is present with a 

maximum thickness of 3.5 feet.

The Blackfeet-Valier area can be 

divided into two parts on the basis of 

differences in the structure of the rocks. 

In the eastern part, which includes the 

Valier field and comprises about two-thirds 

of the total area, the beds dip gently 

westward at angles ranging from nearly horizontal to 5°. In the western part of the 

area, which Includes the Blackfeet field, 

the beds are steeply dipping, folded, and 

broken by thrust faults.

Bridger and Silvertlp fields

The Bridger and Silvert/ip fields are In 

the south-central part of Montana in eastern 

Carbon County. The two fields are part of a 

larger area of coal-bearing rocks that is a 

northward extension of the Bighorn Basin 

region of Wyoming. The coal in each of the 

two fields is of high volatile C bituminous 

rank. It occurs in the Eagle sandstone, 

which consists of several massive sandstone 

members, individually about 35 to 75 feet 

thick, separated by carbonaceous shale. 

Three discontinuous beds of coal are found in 

the shale zones.

^Bridger field. Although the three coal 

horizons mentioned above are all present in 

the Bridger field, ooal of workable thickness is present at only J*ne horizon in any 

one locality.

Coal has been mined near Joliet, 

Fromburg, and Bridger. Near Joliet, in the 

northern part of the Bridger field, a 

section measured in the Barret mine shows 

2.5 feet of coal in two benches, with a 

sandstone roof and a shale floor. Farther

12
south, near Fromburg, approximately the same 

relationships prevail. At Bridger the coal 

is thicker, ranging from 4 to 6 feet in 

thickness, and usually occurs in two or three 

benches separated by bone and shale partings. 

South of Bridger the coal thins again; the 

southernmost exposure of workable coal is in 

T. 93., R. 24 E., where it is 2.5 feet thick 

with a 6-inch parting of shale near the top. 

An analysis on the as-received basis, of 

coal near Bridger shows a heat value of 

10,040 B. t. u. and ash and sulfur contents 

of 13.4 and 0.3 percent, respectively.

The ooal of the Bridger field crops 

out along the eastern edge of a southwestdipping monocline that forms part of the 

east side of the Bighorn Basin of Wyoming. 

The dips in the field range from 2° to 20°. 

Faults, generally trending at right angles 

to the strike of the coal beds, occur in 

nearly all parts of the field but, as a rale, 

do not interfere with mining. A notable 

example is a large fault, about 4 miles 

north of Bridger, where the ooal beds have 

been offset horizontally nearly 2 miles.

Silvertip field. The Silvertip field is 

a small ooal-bearing area south of the 

Bridger field at the Montana-Wyoming border. 

The coal-bearing formation, as in the 

Bridger field, is the Eagle sandstone, which 

is brought to the surface at this point by 

the Silvertip anticline, an elliptical 

structure 8 miles long and 4 miles wide. 

Three coal beds, which probably correspond 

to the beds in the Bridger field, are present 

in the Silvertip field. The lower bed is not 

workable, but coal is mined from the upper 

two. The total thickness of coal in the 

middle bed ranges from 1 foot to 5 feet, and 

that in the upper bed from 3.3 to 5.5 feet. 

The coal beds dip away from the axis of the 

anticline at angles of 15° to 20° SW.and 

22° to 45° NE. Many northeast-trending 

normal faults are present.

Stillwater field

Another small field that contains coal 

in the Eagle sandstone is the Stillwater 

field in the valley of the Stillwater River 

in Stillwater County. Here the Eagle sandstone is 300 feet thick, with coal present in 

one bed near the top of the formation. 

Analyses show the coal to be of high volatile 

C and B bituminous ranks. The coal generally 

occurs in three benches separated by bone, 

shale, and sandstone partings. The total 

thickness of coal in the section of coalbearing rocks ranges from 4 to 5 feet. The 

dip of the coal beds at t.he outcrop is about 

10 . A short distance from the outcrop, 

however, an increase in angle of dip carries 

the coal to considerable depths. An analysis, on the as-received basis, of coal from 

this field shows a heat value of 10,130 

B. t. u. and ash and sulfur contents of 18.7 

and 0.5 percent, respectively.

The Red Lodge field

The Red Lodge field is at the foot of 

the Beartooth Mountains in Carbon County

about 20 miles west of the Bridger and 

Silvertip fields. Unlike these fields, 

however, the coal in the Red Lodge field 

occurs in the Fort Union formation of Tertiary (Paleocene) age, -which is several 

thousand feet higher stratigraphically than 

the coal-bearing Eagle sandstone of the 

Bridger and Silvertip fields.

The Fort Union formation in the Red 

Lodge field is composed mainly of sandstone 

and shale and is believed to be about 5,000 

feet thick. It contains in its upper third 

a ooal-bearing zone 825 feet thick between 

an upper and a lower barren member. The 

coal is tentatively assigned to the high 

volatile 0 bituminous rank on the basis of 

its apparent resistance to weathering. 

Mining has been carried on at the towns of 

Red Lodge and Bear Oreek. In the vicinity 

of Red Lodge, eight beds of ooal known as 

Hos. 1, ij, 2, 3, 4, 4§, 5, and 6 have been 

.worked. Concerning these beds, Woodruff 5y 

statest

...bed No. 1 contains 7 feet of ooal overlain 

by carbonaceous shale and underlain by 4 to 

6 inches of shale above sandstone. Bed No. 

1& contains 5 feet of bright coal with many 

thin partings and has a sandstone roof and 

 hale floor. Bed No. 2 contains 8 feet of 

coal in six benches, with partings of shale 

one-half to 1 inch thick. It rests upon 

shale and is covered by sandstone. Bed No.

3 contains 10 feet of dirty coal.... Bed No.

4 has 10 feet of good coal occurring in 

three benches, with a parting 1 inch thick 

23 inches below the top. This bed is underlain by sandstone and covered by gray shale. 

Bed No. 4£ is composed of 3& feet of coal 

which occurs in several benches and has sha] 

both above and below.... Bed No. 5 contains 

12 feet 1 inch of coal in four benches, with 

partings one-half to 2 inches thick, and lie: 

between beds of hard shale. Bed No. 6 shows 

4 feet 11 inches of coal in a single bench, 

with both roof and floor composed of sandstone. The coal below bed No. 6 ... is 

placed in one group because the interval 

between the beds is not sufficient to allow 

any one ooal to be mined without disturbing 

those above.

Most of the coal mined has been obtained 

from beds Nos. 2, 3, and 4.

The coal beds in the Red Ledge field 

tnin in a southwesterly direction and 

apparently coincide with a shallow basin of 

deposition. They dip gently but irregularly 

from the outcrop on the east side of the 

field to the southwest. At the town of Red. 

Lodge the dip is 18°, decreasing toward the 

southeast to 9° in the western part of the 

Bear Creek district and to 3° a short 

distance farther south. The coal beds are 

terminated to the west by the Beartooth 

Mountain fault, whose eastern side is downthrown 500 to 600 feet. The coal beds are 

believed to continue to the northwest, but 

in this direction the Port Union formation 

passes beneath a cover of alluvium and gravel 

and cannot be observed. The coal-bearing 

rocks have been cut at a few places by small 

igneous intrusions, which, however, have not 

interfered with mining.

£/ Woodruff, E. 6., The Red Lodge coal field, 

Jfontaoat U. S. Geol. Survey Bull. 341, p. 99, 1909.

13
A typical analysis, on the as-received 

basis, of coal from bed No. 4 at Red Lodge, 

shows a heat value of 10,330 B. t. u. and 

ash and sulfur contents of 12.7 and 1.3 

percent, respectively.

Electric field

The Electric field, which is in southern 

Park County in south-central Montana, covers 

an area of less than 20 square miles, of 

which only about 3 square miles can be considered to be underlain by minable coal. The 

coal in this field occurs in rocks of Upper 

Cretaceous age that are designated as the 

Montana group, undifferentiated. These 

sediments, which are about 1,000 feet thick, 

probably are equivalent, at least in part, to 

the Eagle sandstone, but this correlation has 

not been firmly established. Three beds of 

coal, each ranging in thickness from 3 to 5 

feet, including thin partings of clay and 

sandstone, are present in a stratigraphic 

interval of 300 feet in the Montana group. 

Only the uppermost of these three beds has 

been mined extensively.

The Eleoirio field is in a fault block 

that has been depressed several thousand feet 

in relation to the surrounding rooks. The 

rocks in the block are highly folded and 

faulted, and the coal, which is believed to 

be deeply buried in much of the region, is 

exposed at the surface in two small synQlinal 

areas. These are known as the Aldridge 

district, in the northern part of the fault 

block and the Electric district, in the 

southeastern part. In both these districts 

the coal beds dip steeply from a minimum of 

about 24° to nearly vertical and are broken 

by numerous minor faults. Igneous intrusions 

also are present in the area, but few have 

been encountered in mining.

The coal in the Electric field is higher 

in rank than most bituminous coal in the West 

and ranges, in general, from high volatile A. 

bituminous to low volatile bituminous, 

according to the amount of deformation it has 

undergone. An analysis, on the as-received 

basis, of a typical sample of coal from the 

area shows 11,410 B. t. u. and ash and sulfur 

contents of 19.5 and 1.3 percent, respectively.

The coal in the Electric field, particularly that in the uppermost bed, has coking 

qualities, and most of the coal mined from 

the field in the past was used for the 

manufacture of coke. This coke was used for 

a time at the smelters at Anaconda and Butte; 

it was reported to be of good quality but so 

high in aah that the operators were unable 

to meet amelter requirements for coke containing less than 18 percent ash.

Livingston-Trail Creek field

The Livingaton-Trail Creek coal field 

forms a narrow Y-shaped belt that extends 

across three townships for a distance of 

approximately 22 miles in Qallatin and Park 

Counties.

The coal-bearing formation in the field

is made up dominantly of sandstone beds 

totaling 750 to 900 feet in thickness at the 

base of the Montana group of Upper Cretaceous 

age. This unit probably is equivalent to the 

Eagle sandstone, which is the basal formation 

of the Montana group at most localities in 

the State. Coal of workable thickness occurs 

in three or four beds ranging from 2 to 5 

feet in thickness. Several partings of clay, 

shale, or bone separate the coal into benches 

that at most places contain 1 foot to 3 feet 

of coal.

The coal beds in this area are on the 

steeply dipping flanks of anticlinal folds 

and locally are broken by faults. Because 

the rooks have dips that normally range between 40° and 65° and in some places are 

vertical or overturned, the coal is too 

deeply buried a short distance from the outcrops to be mined profitably. Locally the 

coal has been crushed by differential movements in the overlying and underlying beds.

The coal in the Livingston-Trall Creek 

field varies in rank according to the amount 

of deformation it has undergone, but in 

general it is of high volatile A, B, or C 

bituminous rank. An analysis, on the asreceived basis, of a typical sample of coal 

from the field shows 10,950 B. t. u. and ash 

and sulfur contents of 8.5 and 0.6 percent, 

respectively.

In the past, coal mined from several 

parts of this field has been used for the 

manufacture of coke, and at one time 100 

beehive ovens were in operation at Cokedale.

Lombard field

The Lombard coal field is in Broadwater 

and northern Oallatln Counties. Coal is 

present over an area of about 6 square miles 

between the towns of Toston and Lombard. 

The coal, which typically is of high volatile 

A or medium volatile bituminous rank, has 

coking properties, but because of its high 

ash and sulfur content it ha.s never been 

mined for the commercial production of coke. 

An analysis of coal on the as-received basis 

shows 10,060 B. t. u. and ash and sulfur contents of 29.7 and 8.2 percent, respectively.

The coal beds in the Lombard field have 

been much distorted and disturbed by shearing 

and squeezing, so that the coal occurs in 

pockets and lenses. Parts of some beds that 

were mined in the past, however, were as 

much as 6 feet thick. Because of the distortion and shearing, the coal has been 

metamorphosed differentially and locally may 

be graphitic.6/

Flathead field

The Plathead field covers about 150 

square miles along the North Fork Flathead 

River in northern Flathead County. The coal 

in this field occurs in the Kishenehn (?) 

formation, which is of lake-bed origin, of 

Tertiary (Oligocene or Miocene) age. The

14

6/ Stebinger, E., The coal fields of Montana: 

Am. lust. Kin. Eng. Trans. £1913 J, wl. 46, 

p. 910, 1914.
coal is of sub-bituminous B rank.

The coal Is of less than mlnable thickness throughout most of the field, but a 

comp6slte bed made up of several benches, 

the thickest of which Is about 3 feet, occurs 

In the region of the old Emerson mine. A 

typical analysis, on the as-received basis, 

of mined coal from the area shows 8,120 

B. t. u. and ash and sulfur contents of 15.4 

and 2.9 percent, respectively.

The coal-bearing rocks In the Flathead 

field lie in a down-faulted block, and the 

coal beds dip steeply to the northeast at 

angles of 40* or more*

Tertiary lake beds

The lake-bed deposits of Tertiary 

(Oligooene or Miocene) age, which occur in 

many parts of southwestern Montana, contain 

local deposits of lignite. The areal extent 

of these deposits is uncertain, and no 

attempt has been made to show them on the 

index map (fig.l). Areas where lignite has 

been mined or prospected, however, have been 

indicated on the Index map by crosses. The 

lignite beds are known to be lenticular in 

shape and variable in thickness, and they 

probably occur at different stratigraphic 

horizons.

Lignite has been mined at localities 

near Missoula and Drummond, where It Is* 

present In beds ranging In thickness from 5 

to 25 feet. Many of these beds contain bone 

and clay partings, which separate the lignite 

Into benches. A typical analysis, on the asreceived basis, of a sample of lignite from 

this region shows 6,727~B. t. u. and ash and 

sulfur contents of 19.9 and 0.9 percent, 

respectively.

The Tertiary lake beds have been somewhat deformed since their deposition; 

typically they lie in broad, shallow synclines or monoclines. In general, the lake 

beds near the margins of the deposits dip at 

moderate angles toward the centers, but 

locally they are Interrupted by minor' faults.

MONTANA COAL RESERVES

In preparing the accompanying estimate 

of Montana coal reserves, published and 

unpublished detailed geologic reports In the 

files of the Geological Survey, publications 

of the Montana State Bureau of Mines and 

Geology, and similar sources were analyzed. 

Much additional Information is believed to 

be available In the files of mining and 

drilling companies, railroads, and private 

Individuals, and this information ultimately 

will be solicited and Incorporated in subsequent estimates. The present provisional 

estimate, however,, indicates the correct 

extent of the reserves on the basis of the 

assumptions stated and is presented now to 

aid those interested in the development of 

Montana resources.

For the present estimate It was

necessary to establish and define several 

categories of coal according to the rank, 

the reliability of the data available, and 

the thickness of the beds. As a large amount 

of information is available concerning the 

nature and thickness of coal at the outcrop 

in Montana, and as relatively little mining 

and development have been carried on, It was 

necessary also to devise a method of limiting 

the assumed extent of each coal bed at depth. 

These and other similar factors that entered 

Into the preparation of the reserve figures 

are discussed in the following paragraphs.

The rank of the coal was determined 

according to the standard specifications of 

the American Society for Testing Materials 

as presented in the introductory pages of 

this report, and separate calculations were 

made for lignite, sub-bituminous coal, and 

bituminous coal*

The assumed area of each coal bed was 

determined in several ways. If the continuity of a bad was well established by maps 

of the outcrop, mine workings, or,drill 

holes, the entire area of occurrence was 

included even though points of information 

were widely spaced. Similarly, a continuous 

bed extending around a basin or spur was 

considered to underlie the area enclosed by 

the line of outcrop. For all other beds the 

length of outcrop, within chosen thickness 

limits, was considered to establish the 

presence of coal in a semicircular area extending from the outcrop and having a radius 

equal to half the length of the line of outcrop. Where the information consisted of an 

isolated mine working, the coal bed was considered to extend beyond the working in an 

arc with a radius of 1 mile. Where the 

information consisted of data from an Isolated drill hole too far removed to- be Incorporated with other established coal areas, 

the coal bed was considered to extend in a 

circle with a radius of half a mile around 

the hole. Coal in the narrow weathered zone 

at the outcrop was included In the assumed 

areas of coal occurrence, as was also coal 

under roads, railroads, and the like. However, all known areas of burned coal were 

excluded.

Two classes of coal, based on the reliability and quantity of the information 

available for making reserve estimates, were 

established.

The 'class termed "measured and Indicated" reserves includes coal for which 

positive information about thickness and extent was available from surveys of the outcrop, mine workings, and drill records. The 

extent of such coal underground was limited 

everywhere, however, by a line drawn 2 miles 

from the outcrop, so that all coal classed 

as measured and indicated reserves Is less 

than 2 miles from the outcrop and more than 

50 percent less than 1 mile. From a statistical viewpoint, therefore, about 25 percent of the measured and indicated reserves 

could be considered "measured", though it was 

not feasible or desirable to make such a 

separation.

"Inferred" reserves include, In general,

15
coal within the areas delimited as described 

above but lying more than 2 miles from the 

outer op 

'For a few areas in Montana published 

reserve figures were available for individual townships. These figures were not 

differentiated by beds in different thickness groups and, for some townships, included beds as thin as 18 inches, which is 

thinner than the limits established for 

making the current calculation. As the percentage of coal included in the thin 

beds in these few areas was inconsequential, 

the figures were incorporated without change 

in the present estimate, but pending a detailed check of the work and a breakdown of 

the figures by beds in different thickness 

groups, such coal is shown in a separate 

column headed "Unclassified as to thickness" 

in the accompanying tables. For a few other 

areas known to contain coal, but where only

general information was available as to 

thickness or extent of beds, tonnage values 

were assigned on the basis of detailed calculations in nearby areas. This coal also 

is included in the column headed "Unclassified as to thickness" in the accompanying 

tables. When final reserve figures for 

Montana are prepared, it is anticipated that 

most of this tonnage will be transferred to 

the "measured and indicated" class and that 

much of it will be added to the totals in 

the thicker beds.

Several large areas believed to be coal 

bearing, but for which no information was 

available concerning the thickness or extent 

of the beds, were not considered in preparing the accompanying provisional estimate.

The location and extent of these areas 

is shown in tabular form below:

Areas of coal-bearing lands in Montana omitted in reserve estimates

County

Carter

Cuater

Daws on

Fallen

Garfield

Prairie

Rlchland

Roosevelt

Rosebud

Sheridan

Wibaux

Total

Area of coalbearing lands 

omitted 

{square miles)

108

270

915

36

410

1,000

800

460

6

660

110

4,775

Total area of 

coal-bearing 

lands in 

county 

(square miles)

1,305

3,635

2,228

1,383

1,880

1,712

2,026

2,003

3,283

1,700

822

Percent of 

total coalbearing lands 

omitted

8.3

7.4

41.1

2.6

21.8

58.4

39.5

23.0

0.2

38.8

13.4

16
All the areas of coal-bearing lands 

listed contain lignite and, in general, are 

concentrated in .the northeastern part of the 

State where the coal-bearing rocks are concealed by a covering of glacial drift. Detailed work in these areas should materially 

increase the estimate for lignite. It 

should be noted that the total of 4,775 

square miles of coal-bearing lands omitted in 

preparing the estimates is only 9.3 percent 

of the total area of coal-bearing lands in 

Montana.

Except as noted, calculations were made 

by individual beds and by townships, and the 

work was summarized by counties for presentation in the tables. It is hoped that the 

use of small unit areas in making calculations has eliminated the possibility of 

large cumulative errors in the work and will 

facilitate later revision as new data become 

available.

The minimum thickness of coal considered 

in preparing the present estimate was 14 

inches for bituminous coal and 30 inches for 

lignite and sub-bituminous coal. For the 

purpose of classifying the reserves, however, 

separate totals were prepared for coal in the 

following thickness ranges:

Bituminous coal:

More than 36 inches.

24 to 36 inches.

14 to 24 inches. 

Sub-bituminous coal and lignite:

More than 10 feet.

5 to 10 feet.

30 inches to 5 feet.

In December 1948, the.national Bituminous Coal Advisory Council recommended to 

the Secretary of the Interior that estimates 

of bituminous coal reserves in the eastern 

United States be made for the thickness 

ranges 28 to 42 inches and more than 42 

inches. This recommendation was received too 

late for these thickness ranges to be 

adopted for estimating bituminous coal reserves in Montana. It is believed, however, 

that the 24- to 36-inch range selected as a 

basis for preparing the accompanying estimates of bituminous coal will be almost as 

useful as the 28- to 42-inch range, particularly if note is made of the fact that in 

Montana the estimated tonnage of bituminous 

coal in the 24- to 36-inch range is approximately 15 percent less than the tonnage 

would be in the 28- to 42-inch range.

Bituminous coal 

Sub-bituminous coal 

^ignite

Total

Present estimate 

(short tons)

2,362,610,000

132,151,060,000

87.555.270.000

222,046,940,000

In making calculations, the average 

thickness used for each bed was obtained by 

weighting, as far as possible, all thickness 

values according to the area covered by coal 

of the recorded thickness. Partings threeeighths of an inch or more thick, plus an 

equivalent amount of coal, were subtracted 

from the bed thickness. This extremely conservative procedure was followed originally 

by the Geological Survey in establishing 

values of classified coal lands,7/ and as 

many local reserve calculations had been 

made in Montana on this basis, it was 

followed throughout in preparing the present 

provisional estimate. Where partings were 

thicker than the adjoining splits of coal, 

the splits were considered as separate beds 

if they were thicker than the minimum figures 

of 14 and 30 inches for bituminous coal and 

sub-bituminous coal, respectively; otherwise 

they were omitted.

On the basis of about 20 specificgravity determinations of coal from various 

parts of Montana, the value of 1,770 short 

tons per acre-foot was selected as being 

representative of lignite and sub-bituminous 

coal, and 1,800 tons per acre-foot for all 

bituminous coal except in the Red Lodge 

field, Carbon County, where 1,890 tons per 

acre-foot was used.

The method, as outlined, of determining 

the assumed area of occurrence of each coal 

bed eliminated from consideration practically 

all coal more than 2,000 feet below 'the surface. The present estimate was restricted, 

therefore, to coal lying between the surface 

and a depth of 2,000 feet. Of the total 

amount of coal included in this range, however, a very large fraction, perhaps 75 percent, is no more than 1,000 feet below the 

surface.

Tables 1, 2, 3, and 4 show the original 

coal reserves in Montana calculated by rank 

of coal, by county, by class of coal according to the reliability and abundance of 

information available for making estimates, 

and by coal beds in different thickness 

groups. A comparison of the totals for each 

rank with totals obtained by Campbell §/ in 

1928 shows several differences, which are 

due in part to differences in the assumptions 

used in making the two estimates. The 

original reserves of coal in each rank 

according to the present estimate and Campbell's estimate are as follows:

Campbell's 1928 estimate 

(short tons)

2,655,000,000

62,985,000,000

315.474.000.000

381,114,000,000

17

I/ Sadth, 6. 0., and others, The classification of the public lands: U. S. Qeol. Surrey Bull. 

537, P. 70, 1913.

8/ Bach, J. W., Hendrlcks, T. A., and Tbenges, 

A. L., Coal, in Mineral position of the United 

States* Hearings before a Bubcoswitt** of the Ooa- 

 Itte* oil Public lends, U. S. Senate, 80th Gong., 

1st teas., pp. 231-23$, thy 15, 16, and 20, 1%?.
Table 1. Estimated original bituminous coal reserves in Montana, in millio

County

Broadwater.

Cascade. . . .

Glacier..,* <

!

Judith Basin

H

00 Meagher, . . .

POT* If

Fondeina. . * . ; 

Stillwater.

Total.

Measured and indicated reserves

In beds 

14 to 24 

inches 

thick

39.33 

81.10 

59.28 

6.75 

65.70

21.89 

4.73

278.78

In beds 

24 to 36 

inches 

thick

5.66 

113.11 

74.70 

83.38 

19.14 

45.65

 i 6.05

347.69

In beds 

more than 

36 inches 

thick

621.97 

234 . 12 

126.75 

6.30 

44.77 

0.53

 

1.89

1,036.33

Total

5.66 

774.41 

389.92 

269.41 

32.19 

156.12 

0.53

21.89 

12.67

1,662.80

Inferred reserves

In beds 

14 to 24 

inches 

thick

42.65 

38.37 

31.16

54.90

167.08

In beds 

24 to 36 

inches 

thick

 

82.12

 

30.73 

1.17 

29.11

 

0.61

 

 

143.74

In beds 

more than 

36 inches 

thick

348.04 

6.83 

10.10

3.80

20.22

388.99

Total coal in beds 14 to 24 inches thick............. 

Total coal in beds 24 to 36 inches thick............. 

Total coal in beds more than 36 inches thick......... 

Total coal in beds of unclassified thickness......... 

Grand total..................................... 
Table 2. Estimated original sub-"bituminous coal reserves in Montana In millions 

County

Big Horn. . .

Chouteau . . .

Oar field... 

Hill.......

Husselshell 

£ Park. ......

Phillips . . . 

Powder River 

Rosebud. ... 

Treasure . . . 

Yellows tone

Total .

Measured and -indicated reserves

In beds 

2& to 5 

feet 

thick

420.46

0.90 

163.58 

1.49 

425.66 

28.00 

4.12 

0.44

 * 

2,842.72 

1,504.74

* 

* 

5,392.11

In beds 

5 to 10 

feet 

thick

1,273.54

0.58 

1,570.48

110.28

8,034.63 

4,496.11

15,485.^2

In beds 

more than 

10 feet 

thick

2,478.46

779.80

26.87

18,525.97 

4,559.09

26,370.19

Total

4,172.46

1.48 

2,513.86 

1.49 

562.81 

28.00 

4.12 

0.44

29,403.32: 

10,559.94

47,247.92

Inferred reserves

In beds 

2^ to 5 

feet 

thick

322.02 

21.63

0.05 

39.31 

48.55

3.91 

3.50 

760.26 

1,126.92

2,326.15

In beds 

5 to 10 

feet 

thick

1,717.75

10.62

8.05

3,295.87 

4,213.65

9,245:94

In beds 

more than 

10 feet 

thick

2,685.54

7, 525,, 03 

5,764,35

15,974.92

T

4

11

11,

27,

Total coal in beds 2^ to 5 feet thick ....... 7,718.26

Total coal in beds 5 to 10 feet thick ....... 24,731.56

Total coal in beds more than 10 feet thick .. 42,345.11

Total coal in beds of unclassified thickness. 57,556.15

Grand total............................. 152,151.06
Table 5. Estimated original lignite reserves in Montana, in millions of 

County

Fallon. .....

powder River

1*T»Q 1 1*1 A

Rlchland. ... 

Roosevelt. . .

Sheridan.* «.

Vo 11 Air

1J4 VlOli *v

Total.

Measured and indicated reserves

In beds 

2| to 5 

feet 

thick

366.99 

1,219.46

301.28 

416.54

271.18 

235.46 

366.78 

657.71

467.60

573.17

4,876.17

In beds 

5 to 10 

feet 

thick

56.40 

162.43

883.85 

247.45

177.33 

565.69 

1; 281. 58 

1,591;33

210.97

1,436.04

6,613.07

In beds 

more than 

10 feet 

thick

117.60

1,335.99 

160.89 

830.90 

0.46

100.01

20.18

2,566.03 .

Total

423.39 

1,499.49

1,185.13 

663.99

1,784.50 

962.04 

2,479.26 

2,249.50

778.58

2,029.39

14,055.27

Inferred reserves

In, beds 

2£ to 5 

feet 

thick

40.08 

31.22

1,088.98 

487.56

371,00

8.87 

153.04 

4,436^79 

839.24

225.25

2,495.72

10,177.75

In beds 

5 to 10 

feet 

thick

1,388.38 

18»09

19.70 

205.32 

147.91 

8,213.70 

1,035.49

1.54

2,105.75

13,135.88

In beds 

more than 

10 feet 

thick

435.00

435.00

i T

2,4

5

3

6

3

12,6

1,8

2

4,6

23,7

I/ Incomplete. See p. 16.

Total coal in beds 2£ to 5 feet thick......... 15,053.92

Total coal in beds 5 to 10 feet thick......... 19,748.95

Total coal in beds more than 10 feet thick.... 3,001.03

Total coal in beds of unclassified thickness.. 49,729.57

Grand total.............................. 1/87,533.27
Table 4. Total estimated original coal reserves in Montana, 

In millions of short tons

County

Blaine ......

Daniels .....

Oar field....

Glacier. ....

Hill........

Judith Basin

MAA crfa AT*

P«T>lr

Phillips....

Powder River

Pr»O 1 T»"1 A

Richland. . . .

Stillwater..

VA T T ATT

Yellowstone.

Total.

Bituminous

5.66

1,247.22

435.12

341.40

33.36

OA* Q«

O

KI

ori p»

21.89

1 fi> fi7

2,362.61

Sub -b i tuminou s

43,500.65

39,73

1 AO

2,678.86

1.54

612.74

76.66

3 471 4Q

12.40 .

3 Rn

40,984.48

38,873.78

,

1,303.66

CQ/> nr\

132,151.06

Lignite

2/463.47

2/2,198.86

S

QAA no

2/11,110,49

O/O RAA OR

/«>

23.00

24,871.57

19.70

2,433.69

2/1,581.27

2/21,085.62

2/4,164.23

2/10.10

2/5,763.82

257.93

2/7,040.73

2/87,533.27

Total

43,500.65

39.73

5.66

1,247.22

2/463.47

435.12

1.48

P/4 fl77 71

S QftA "7P

S/11,110,49

2/2,544.08

*iO QA

S/612.74

33.36

23.00

76.55

243.93

24,871.57

0.53

19.70

3,471.49'

33.23

3.50

21.89

43,418.17

2/1,581.27

2/21,085.62

2/4,164.23

2/38,883.88

2/5,763.82

12.67

1,303.66

257.93

2/7,040.73

590.20

2/222,046.94

Percent of total

1 q c

(1)

(1)

0.6

0.2

O P

(1)

2

0

1 p

5.0

1.1

0.2

0.3

(1)

(1)

(1)

0.1

11.2

(1)

(1)

1.6

(1)

(1)

(1)

19.5

0.7

9.4

1.9

17.5

2.6

(1)

0.6

0.1

3.2

0.3

99.9

I/ Less than 0.1 percent. 

Incomplete. See p. 16.

21
Table 5. Coal production in 

/"Figures from U. 3. Bureau of

Montana during the years 1957-47, in shor

Mines, Minerals Yearbooks, 1938-48, inclu

County. ....

Cascade.. . .

Chouteau . . .

Flathead . . .

Hill .......

Musselshell

jg Richland...

Roosevelt..

Rosebud... .

Sheridan. ..

Total*

1937

15,327

389, 036

434,595

8,033

3/10,288

3,485

11,079

* 

* 

787,665

14,667

12,337

1,248,837

8/17,019

13/12,825

2,965,193

1938

1/12,216

331,118

490,587

8,021

3/7,697

1,438

7/4,261

8,738

8/8,784

9/1,815,707

12,911

7,559

....

15,156

14/7,457 -' 9

2,731,650

1939

....

* * 

* »

5,627

4/6,898

... *

....

6,759

737,947

13,828

4,527

....

15,148

15/1.995.970

2,803,804

1940

....

 ZOO Qf^^

OOO 9 \y\JO

461,692

5,018

4/8,579

....

7 QQQ , yoo

4

<ZCQ

, OOO

787 , 355

10/19,362

....

1,127,915

15,965

1 & /P7 O1Q LO/ 61) (COO

2,267,200

1941

* 

411/098

506,261

5,854

4/19,681

 

V 342

3,455

843,766

10/15,834

....

1,399,350

19,823

17 /PI P7O * ' / iC-I. , <C l w

3,253,724

1942

1O,833

635,839

438,569

3,741

4/19,967

| 2,235

; 2,547

4,551

 * 

970,246

11/8,950

....

1,708,641

20,221

18/2,342

3,828,682

1945

15,127

546,437

489,174

5,930

5/25,780

....

1,136,540

13/20,423

....

12/2.579.658

20,180

4,853,049

1944

9,18

637,31

482,60

2,62

15,78

6/4,67

1,01

1,142,80

11/15,09

....

2,514,60

18,05

19/2,17

4,844,049

Includes Phillips County.

Includes Chouteau County.

Includes Wibaux County.

Includes Dawson County.

Includes Dawson and Valley Counties.

Includes Valley County.

Includes Pondera County.

Includes Daniels and Valley Counties.

Includes Rosebud County.

Includes Roosevelt County.

Includes McCone and Roosevelt Counties,

Includes Fergus County,

13/ Includes Judith Basi

Powder River, and Toole Cou

14/ Includes Gallatin, P

Stlllwater Counties.

IS/ Includes Blaine, Car

Plathead, Qallatin, Judith 

Pondera, Powder River, and 

16/ Includes Blaine, Fer

Park, Phillips, Pondera, an

IT/ Includes Blaine, Fer

Judith Basin, Park, Phillip

River Counties.

18/ Includes Park and Po

Includes Toole Count
It should be noted in comparing these figures 

that although the same minimum thicknesses 

were assumed for coal in both estimates, the 

present estimate was based on extremely conservative assumptions as to the areal extent 

and volume of each bed and includes only 

coal no more than 2,000 feet below the surface, whereas Campbell's estimate included 

coal lying between the surface and a depth 

of 3,000 feet. Also, Campbell made statistical allowance for coal in unmapped coalbearing areas and for coal in areas covered 

by glacial drift. In general, no such 

allowances were made in preparing the 

present estimate. The increase in the 

present estimate of original reserves of subbituminous coal in spite of the conservative 

methods of calculating tonnage is due to the 

inclusion of large tonnages of coal in southeastern Montana, where much detailed mapping 

has been done in recent years by the 3eological Survey. The decrease in the present 

estimate of the original reserves of lignite 

is due in part to the fact that no allowance 

was made for coal in areas in eastern 

Montana where coal is known to be present, 

but where no mapping has been done, and for 

large areas in northeastern Montana where the 

coal-bearing rocks are concealed by glacial 

drift. It is believed, therefore, that 

further work in coal-bearing areas not 

included in the present estimate will result 

in an increase in the total original 

reserves.

Table 5 shows the total production'of 

coal in Montana by counties for the years 

1937-47, inclusive. It is noteworthy that 

Bix counties, Big Horn, Powder River, McCone, 

Rosebud, Riohland, and Dawson, which contain 82 percent of the original reserves, 

yield leas than 50 percent of the annual 

production of the State. Furthermore, Big 

Horn County, which contains 19.6 percent of 

the original reserves, has never produced 

enough coal to be included in the production

table, and Powder River County, which contains 19.5 percent of the total reserves and 

the largest apparent reserves of thick coal 

of any county in the State, has produced only 

a few thousand tons. Rosebud County, the 

largest producer in recent years, contains 

17.5 percent of the original reserves, whereas Musselshell County, the second largest 

producer, contains only 1.6 percent of the 

reserves. These differences are explained 

primarily by the lack of markets near the 

reserves, the lack of transportation facilities, and also the fact that the lower 

ranks of coal slack easily during transportation and storage.

Three counties Plathead, Qallatin, and 

Toole are listed in the production table 

but do not appear in the reserve tables. 

This is in accord with the principles, 

followed in preparing the estimates, of 

omitting areas known to contain thin and 

bony coal and areas where quantitative information about the coal was lacking.

The total recorded production of coal 

in Montana from established mines since 

operations began to January 1, 1949, is 

about 155 million tons. Actual production, 

including that from wagon mines, is probably 

about 175 million tons. Studies made in 

1923 of the bituminous coal mining industry 

have shown that the average amount of coal 

lost in mining is 34.7 percent of the coal 

originally in the ground.9/ For each ton 

produced, therefore, more than half a ton 

(0.5314) is lost. Assuming mining losses of 

this magnitude for Montana,-the total coal 

mined and lost in mining in Montana to 

January 1, 1949, is approximately 268 million 

tons. The remaining reserve is about 

221,779 million tons, or 9.9.8 percent of the 

original reserves. It should be noted that 

losses of approximately 35 percent may be 

expected in mining the remaining reserves.

<£/ Bice, G. S., and Paul, J. W., Amount and 

nature of lossea in mining bituminous coal in eastern United States: U. S. Coal Coon. Rapt., pt. 3, 

pp. 18U-76, 1923.

23
SELECTED BIBLIOGRAPHY

The following bibliography lists only 

publications that contain detailed information about Montana coal resources. Host 

of these publications are bulletins of the 

Geological Survey; they contain maps showing 

outcrops of the coal beds, structure of the 

coal-bearing rooks, detailed measured 

sections of the coal beds, and related information. The publications are listed in numerical order according to the following 

classification: Geological Survey bulletins, 

other publications of the Geological Survey, 

and miscellaneous publications. The publications of the Geological Survey marked by

an asterisk (*) are out of print. The 

bulletins not so marked were available on 

April 1, 1949, from the Superintendent of 

Documents, Washington 25, D. C., at the 

prices indicated. All the publications 

listed are available for consultation in 

most large public and university libraries 

and frequently are obtainable from dealers 

in second-hand scientific books. In Montana, 

many of the publications should be available 

at the libraries of the Montana State College, 

Bozeman; Montana School of Mines, Butte; 

Historical Society of Montana and Public 

Library, Helena; Fergus County High School, 

Lew!atown; and State University, Missoula. 

An index to the publications in the bibliography is given on succeeding pages.

Bulletins of the United States Geological Survey

#225.(J) Coal of the Bighorn Basin in northwest Wyoming, by C. A. Fisher, "pip. 345-564, 1905.

#285.(f) Development of the Bear Creek coal fields, Mont., by C. A. Fisher, pp. 269-270, 1906; 

The North Dakota-Montana lignite area, by A. G. Leonard, pp. 516-530, .1906.

#316.(o) The Great Falls coal field, Mont., by C. A. Fisher, pp. 161-173, pi. x, 1907; Coals of 

Carbon County, Mont., by H. H. Darton, pp. 174-195, pi. xi, 1907; The coal fields 

of Dawson, Rosebud, and Ouster Counties, Mont., by A. G. Leonard, pp. 194-211, 

pi. xii, 1907.

«341.(a) The Sentinel Butte lignite field, N. Dak. and Mont., by A. G. Leonard and C. D. Smith, 

pp. 15-35, pi. ii, 1909; The Miles City coal field, Mont., by A. J. Collier and 

C. D. Smith, pp. 36-61, pi. iii, 1909; The Bull Mountain coal field, Mont., by 

L. H. Woolsey, pp. 62-77, pi. iv^ 1909;'Coal near the Crazy-Mountains, Mont., by 

R. W. Stone, pp. 78-91, pi. v, 1909; The Red Lodge coal field, Mont., by E. G. 

Woodruff, pp. 92-107, pi. vi, 1909; The Lewistown coal field, Mont., by W. R, 

Calvert, pp. 108-122, pi. vii, 1909.

#341.(b) Coal fields of the northeast side of the Bighorn Basin, Wyo., and of Bridger, Mont., 

by C. W. Washburne, pp. 165-199, .pi. x, 1909.

#356. Geology of the Great Falls coal field, Mont., by C. A. Fisher, 85 pp., 12 pis., 1909,

#381.(a) The Fort Peck Indian Reservation lignite field, Mont., by C. D. Smith, pp. 40-59,

pi. iii, 1910; The central part of the Bull Mountain coal field, Mont., by R. W. 

Richards, pp. 60-81, pis. iv-v, 1910; The Milk River coal field, Mont., by L. J. 

Pepperberg, pp. 82-107, pi. vi, 1910j Notes on the coals of the Ouster National 

Forest, Mont., by C. H. Wegemann, pp. 108-114, pi. vii, 1910.

#390. Geology of the Lewistown coal field, Mont., by W. R. Calvert, 83 pp., 5 pis., 1909.

#431.(b) The eastern part of the Bull Mountain coal field, Mont., by C. T. Lupton, pp. 163-189, 

pla. vi-vii, 1911.

#471.(d) Geology of certain lignite fields in eastern Montana, by W. R. Calvert, pp. 187-201,

1912; The Baker lignite field, Ouster County, Mont., by C. F. Bowen, pp. 202-226, 

pis. xiv-xv, 1912; The Terry lignite field, Ouster County, Mont., by F. A. Herald, 

pp. 227-270, pis. xvi-xviii, 1912; The CHendive lignite field, Dawson County, 

Mont., by J. H. Hance, pp. 271-283, pis. xix-xx, 1912; The Sidney lignite field, 

Dawson County, Mont., by Eugene Stebinger, pp. 284-318, pis. xxi-xxiv, 1912; The 

Culbertson lignite field, Valley County, Mont., by A. L. Beekly, pp. 319-358, pis, 

xxv-xxvii, 1912.

#471.(e) The southern extension of the Milk River coal field, Chouteau County, Mont., by L. J. 

Pepperberg, pp. 359-383, pi. xxviii, 1912; The Livingston and Trail Creek coal 

fields, Park, Gallatin, and Sweetgrass Counties, Mont., by W. R. Calvert, 

pp. 384-405, pi. xxix, 1912; The Electric coal field, Park County, Mont., by W. R. 

Calvert, pp. 406-422, pi. xxx, 1912.

#471.(j) Miscellaneous analyses of coal samples from various fields of the United States, 

pp. 629-655, 1912.

#531.(f) The Little Sheep Mountain coal field, Dawson, Ouster, and Rosebud Counties, Mont., by 

G. 3. Rogers, pp. 159-227, pis. xi-xlii, 1911.

#531.(g) Coal in the Tertiary lake beds of southwestern Montana, by J. T. Pardee, pp. 229-244, 

pi. xiv, 1911.

24
#531. (m) Miscellaneous analyses of ooal samples from various fields of the United States, 

pp. 331-355, 1911.

#541.(h) Lignite in the vicinity of Plentywood and Scobey, Sheridan County, Mont., by C. M. 

Bauer, pp. 293-315, pis. xv-xvii, 1912; Geology and ooal resources of the area 

southwest of Ouster, YeHowstone and Bighorn Counties, Mont., by G. S. Rogers, 

pp. 316-328, pi. xviii, 1912'; Coal discovered in a reconnaissance survey between 

Musselshell and Judith, Mont., by C. F. Bowen, pp. 329-337, pi. xix, 1912; The 

Cleveland coal field, Blaine County, Mont., by C. F. Bowen, pp. 338-355, pi. xx, 

1912; The Big Sandy coal field, Chouteau County, Mont., by C.-F. Bowen, pp. 356- 

378, pi. xxl, 1912.

#541.(k) Analyses of coal samples from various fields of the United States, by M. R. Campbell, 

pp. 491-626, 1912.

#621.(k) Geology and ooal resources of northern Teton County, Mont., by Eugene Stebinger, 

pp. 117-156, pi. xv-xvi, 1915.

#621.(p) Analyses of coal samples from various carts of the United States, by M. R. Campbell and 

F. R. Clark, pp. 251-376, i-vii ^"including title page, contents, list of illustrations, and index to volume__/, 1915. ,

#641.(g) Geology of the Upper Stillwater Basin, Stillwater and Carbon Counties, Mont., with 

special reference to coal and oil, by W. R. Calvert, pp. 199-214, pis. xx-xxi, 

1917.

#641.(h) Geology of the Hound Creek district of the Great Falls coal field, Cascade County, 

Mont., by V. H. Barnett, pp. 215-231, pi. xxii, 1917.

#647. The Bull Mountain coal field, Musselshell and YeHowstone Counties, Mont., by L. E. 

Woolsey, R. W. Richards, and C. T. Lupton, 218 pp., 36 pis., 1917.

#661.(i) Phosphatic oil shales near Dell and Dillon, Beaverhead County, Mont., by C. F. Bowen, 

pp. 315-328, i-viii /"including title page, contents, list of illustrations, and 

index to volume_J7, 1918.

#729. Oil shale of the Rocky Mountain region, by D. B. Winchester, 204 pp., 18 pis., 1923.

#749. Geology of the Tullock Creek coal field, Rosebud and Big Born Counties, Mont., by 

G. S. Rogers and Wallace Lee, vi, 181 pp., 16 pis., 1923.

#751.(e) The Scobey lignite field, Valley, Daniels, and Sheridan Counties, Mont., by A. J. 

Collier, pp. 157-230, pis. xxi-xxix, 1923-24.

#751.(f) The Ekalaka lignite field, southeastern Montana, by C. M. Bauer, pp. 231-267, 

pis. xxx-xxxiv , 1923-24.

806.(b) The northward extension of the Sheridan coal field, Big Horn and Rosebud Counties, Monti 

by A. A. Baker, pp. 15-67, pis. 6-29, 1928. 45 cents.

#812.(a) The Porsyth coal field, Rosebud, Treasure, and Big Horn Counties, Mont., by C. B. 

Dobbin, pp. 1-55, pis. 1-10, 1929.

#822.(a) Geology and mineral resources of parts of Carbon, Big Horn, Yellowstone, and Stillwater 

Counties, Mont., by R. S. Khappen and G. F. Moulton, pp. 1-70, pis. 1-5, 1930.

831.(b) The Ashland coal field, Rosebud, Powder River, and duster Counties, Montana, by N. W. 

Bass, pp. 19-105, pis. 3-37, 1931-32. 80 cents.

847.(b) The Rosebud coal field, Rosebud and Ouster Counties, Mont., by W. G. Pierce, pp. i-v, 

43-120, pis. 5-21, 1936. $1.25.

847.(c) The Richey-Lambert coal field, Richland and Dawson Counties, Mont., by F. S. Parker, 

pp. i-iv, 121-174, pis. 22-27, 1936. 35 cents.

847.(f) Geology and mineral resources of north-central Chouteau, western Hill, and eastern

Liberty Counties, Mont., by W. G. Pierce and C. B. Hunt, pp. i-iv, 225-270, i-vi, 

pis. 36-43, 1937. ^"includes title page, contents, list of illustrations, and 

index to volume._/ 35 cents.

#856; Geology of Big Horn County and the Crow Indian Reservation, Mont., with special reference to the water, coal, oil, and gas resources, by W. T. Thorn, Jr., G. M. Hall, 

C. H. Wegemann, and G. F. Moulton, vii, 200 pp., 15 pis., 1935.

905. The coal resources of McCone County, Mont., by A. J. Collier and M.* M. Khechtel, vii, 

80 pp., 16 pis., 1939. 75 cents.

906.(c) The Mizpah coal field, Ouster County, Mont., by F. S. Parker and D. A. Andrews, pp. 

i-v, 85-133, pis. 16-^40, 1939 £ 1940_/. |l.50

25
Other publications of the United States Geological Survey

#A 22 III. (J) Twenty-second Annual Report, pt. 3, oh. J: The Rooky Mountain coal fields, by 

L. 3. Storrs, pp. 415-471, pis. xxix-xxx, 1902.

#P 100. (a) Professional Paper 100, oh. at The ooal fields of the United States, General 

Introduction, by M. R. Campbell, pp. 1-33, pi. 1, 1929 /originally 

published In June 1917_7.

#QP l. Geologic Folio 1: Llvlngston, Mont., by J. P. Idling* and W. H. Weed, 

pp., 4 maps, 1894.

*GP 24. Geologic Folio 24: Three Forks, Mont., by A. 0. Peale, £X7 pp., 4 maps, 1896.

*GP 55. Oeologlo Folio 55: Fort Benton, Mont., by W. H. Weed, £$J pp., 4 maps, 1899.

*OF 56. Geologic Folio 56: Little Belt Mountains, Mont., by W. H. Weed, £ll7 PP»» 

4 maps, 1899.

*W 221. Water-Supply Paper 221: Geology and water resources of the Great Falls region, 

Mont., by C. A. Fisher, 89 pp., 7 pis., 1909.

«W 518. Water- Supply Paper 518: Ground water In Musaelshell and Golden Valley Counties, 

Mont., by A. J. Bills and 0. E. Meinzer, vl, 92 pp., 5 pis., 1924.

«W 599. Water-Supply Paper 599: Ground water In Yellowstone and Treasure Counties, Mont. 

by G. M. Hall and C. 3. Howard, vi, 118 pp., 7 pis., 1929.

W 600. Water-Supply Paper 600: Geology and ground-water resources of central and 

southern Rosebud County, Mont., by B. C. Reniok, x, 140 pp., 12 pis., 

1929. 35 cents.

Miscellaneous publications

M 11. Geology and artesian water resources along Missouri and Milk Rivers in northeastern Montana, by E. S. Perry: Montana Bur. Mines and Geology Mem. 11, 

34 pp., 1934.

MB 1. Geology and economic deposits of a portion of eastern Montana, by J. P. Rowe and 

R. A. Wilson: Montana Univ. Studies, ser. 1, pp. 5-58, 1916.

Mff 37. Montana coal and lignite deposits, by J. P. Rowe: Montana Univ. Bull. 37, 

geol. ser. 2, 82 pp., 1906.

Mff 50. Some economic geology of Montana, by J. -P. Rowe: Montana TJniv. Bull. 50, 

geol. ser. 3, 67 pp., 1908.

T 529. Analyses of Montana coals: U. S. Bur. Mines Tech. Paper 529, 123 pp., 1932.

26
IHDEX TO BIBLIOGRAPHY

This index refers to the preceding bibliography. The abbreviations used for various publications are as follows: A, Annual Report, U. 3. Geological Survey; B, Bulletin, U. S. Geological Survey; GP, Geologic Polio, U. S. Geological Survey; P, Professional Paper, U. 3. Geological Survey; M, Hemoir, Montana Bureau of Mines and Geology; Mff, Bulletin, University of 

Montana; T, Technical Paper, U. S. Bureau of Mines) W, Water-Supply Paper, U. 3. Geological 

Survey.

Analyses ................................................. B 471 J, 531 m, 541 k, 621 p; T 589

Ashland field (Rosebud, Powder River and Ouster Counties) ............................ B 831 b

Baker field (Ouster and Fallen Counties) ............................................. B 471 d

Bear Greek field (Carbon County) ............................ B 225, 285 f, 516 o, 341 a; HO 50

Beaverhead County ........................................................ B 661 1, 789} W 37

Big Horn County ........................................ B 641 h, 749, 806 b, 818 a, 888 a,856

Big Sandy field (Chouteau County) .................................................... B 541 h

Bitteroot Forest Reserve (Ravalli and Miss oula Count lea) ......v....................... B 531 g

Blaokfeet field (Glaoier, Pondera, and Toole Counties) ............................... B 681 k

Blaine County ......................................................... B 381 a, 471 e, 541 h

Bridger field (Carbon County) ....................................... ..<. B 316 o, 341 b; MO 50

Broaawater County ...................................................................... GF 24

Bull Mountain field (Musselshell and Yellowstone Counties) ........................... B 341 a

381 a, 431 b, 647

Carbon County ......................... B 225, 286 f, 316 o, 341 a, 341 b, 641 g, 828 a; HO 50

Carter County ........................................................................ B 751 f

Cascade County ................................... B 516 o, 356, 641 h; GF 55, 56; KU 50; W 281

Chouteau County ....................................................... B 641 h, 847 f; GP 55

Cleveland field (Blaine County) ...................................................... B 541 h

Crazy Mountain field (Meagher, Park, and Wheatland Counties) ......................... B 341 a

Crow Indian Reservation (Big Horn County) .............................................. B 856

Gulbertson field (Sheridan and Roosevelt Counties) ................................... B 471 d

Cluster County .........................B 285 f, 316 c, 341 a, 471 d, 531 f, 831 b, 847 b, 906 o

Ouster district (Yellowstone and Big Horn Counties) .................................. B 541 h

Ouster National Forest (Powder River and Rosebud Counties) ........................... B 381 a

Daniels County ... **«.................................................... B 381 a, 541 h, 751 e

Dawson County ................................................... B 285 f, 316 c, 471 d, 847 c

Deer Lodge County ...................................................................... B 531 g

Ekalaka field (Carter and PalIon Counties) ........................................... B 751 f

Electric field (Park County) ................................................... B 471<e; MU 50

Fallori County .......................................................... B 285 f, 471 d, 751 f

Fergus County ......................................... B 341 a, 390, 541 h; GP 55; M 11; MU 50

Flint Creek field (Granite County) ........'........................................... B 531 g

Forsyth field (Rosebud, Treasure, and Big Horn Counties).............................. B 812 a

Port Benton quadrangle (Cascade, Judith Basin, Fergus, and Chouteau Counties) ...'....... GF 55

Port Peck Indian Reservation (Daniels, McCone, Richland, Roosevelt, Sheridan and Valley

Counties)........................................................................ B 381 a

Gallatin County ................................................ B, 471 e; GP 1, 24, 56; MU 50

Garfleld County ....................................................................... B 316 c

Glacier County ........................................................................ B 621 k

Glendive field (Dawson, Prairie, and Wibaux Counties) ................................ B 471 d

Golden Valley County ................................................................... W 518

Granite County ..................................v.................................... B 531 g

Great Falls field (Cascade, Judith Basin, and Meagher Counties).......... B 316 a, 356, 641 h;

MtJ 50; W 221

Hill County ............................................................ B 381 a, 471 e, 847 f

Hound Creek district (Cascade and Meagher Counties) .................................. B 641 h

Jefferson County ....................................................................... GF 24

Judith Basin County ............................... B 316 c, 341 a, 356, 390; GF 55, 56; W 221

Judith district (Fergus, Musselshell, and Petroleum Counties) ........................ B 541 h

Lewlstowri field (Fergus, Judith Basin, and Wheatland Counties) .................. B 341 a, 390

Liberty County ........................................................................ B 847 f

Little Belt Mountains quadrangle (Cascade, Judith Basin, Meagher, Gallatin, Park,

Sweet Grass, and Wheatland Counties) .............................................. GF 56

Little Sheep Mountain field (Prairie, Custer, and Rosebud Counties)................... B 531 f

Livingston quadrangle (Gallatin, Park, Sweetgrass, and Stillwater Counties) .... B 471 e; GF 1

Madison County ......................................................................... GF 24

McCone County ................................................................... B 381 a, 905

Meagher County ......................................................... B 341 a, 641 h; GF 56

27
Miles City field (Ouster County) ..................................................... B 341 a

Milk River field (Blaine and Hill Counties) ..................................... B 381 a, 471 e

Missoula County ...................................................................... B 531 g

Mizpah field (Ouster County) .......................................................... B 906 o

Montana (general) .................................................. A 22 III J; P 100 a; WF 1

Muaselshell County .................................. B 341 a, 381 a, 431 b, 541 h, 647; W 518

Park County .............................................. B 341 a, 471 e; OP 1, 2*, 56; MET 50

Petroleum County ..................................................................... B 541 h

Phillips County ......................................................................... H 11

Pine Ridge field (Big Horn and Yellowstone Counties) ................................. B 541 h

Plentywood and So obey districts (Daniels and Sheridan Counties) ....................... B 541 h

Pondera'County ....................................................................... B 681 k

Powder River County ........................................................... B 381 a, 831 b

Powell County ........................................................................ B 531 g

Prairie County .................................................. B 285 f, 316 o, 471 d, 531 f

Ravalli County ................................................................ B 531 g; 107 37

Red Lodge field (Carbon County) ............................ B 825, 316 o, 341 a, 641 g; MU 50

Richey-Lambert field (Riohland and Dawaon Counties)................................... B 847 o

Riohland County ......................................................... B 381 a, 471 d, 847 o

Roosevelt County ............................................................... B 381 a, 471 d

Rosebud County ...................... B 316 o, 381 a, 531 f, 806 b, 812 a, 831 b. 847 b; W 600

Rosebud field (Rosebud^and Ouster Counties) ................................... B 847 b; W 600

Soobey field (Valley, Daniels, and Sheridan Counties) ......................... B 541 h. 751 

Sentinel Butte field (Wibaux County) ................................................. B 341 a

Sheridan County ................................................. B 381 a, 471 d, 541 h, 751 e

Sheridan field, northward extension (Big Horn and Rosebud Counties) .................. B 806 b

Sidney field (Riohland, Dawson, and Wibaux Counties) ................................. B 471 d

Silver Bow County .................................................................... B 531 g

Silvertip field (Carbon County) ...................................................... B 341 b

Stillwater County ...................................................... B 641 g, 822 a; OF 1

Stillwater field fStillwater and Carbon Counties) .................................... B 641 g

Sweet Grass County ......................................................... B 471 e; OP 1, 56

Terry field .(Ouster. Fallen, Wibaux, and Prairie Counties) ........................... B 471 d

Tertiary lake beds (Deer Lodge, Granite, Missoula, Powell, Ravalli, and Silver Bow

Counties) ....................................................................... B 531 g

Tertiary lake beds (Beaverhead County) ................................... B 661 i, 729; MtJ 37

Three Forks quadrangle (Broadwater, Gallatin, Jefferson, Madison, and Park Counties).... OF 24

Toole County .......................................................................... B 621 k

Trail Creek field (Park, Gallatin, and Sweet Grass Counties) ............ B 471 e; OP 1; MU 50

Treasure County ......................................................... B 749, 812 a; W 599

Tullock Greek field (Big Horn and Treasure Counties) ................................... B 749

Upper Stillwater Basin (Stillwater and Carbon Counties) .............................. B 641 g

Valier field (Pondera, Glacier, and Toole Counties) .................................. B 621 k

Valley County ........................................................................ B 751 e

Wheatland County .......................................................... B 341 a, 390; OF 56

Wibaux County .................................................... B 285 f, 316 o, 341 a, 471 d

Yellowstone County ............................ B 541 a, 381 a, 431 b, 541 h, 647, 822 a; W 599

28 59»»T