GEOLOGICAL SURVEY CIRCULAR 293 

COAL RESOURCES OF 

THE UNITED STATES 

(A progress report, 

October 1, 1953) 

UNITED STATES DEPARTMENT OF THE INTERIOR 

Douglas McKay, Secretary 

GEOLOGICAL SURVEY 

W. E. Wrather, Director 

GEOLOGICAL SURVEY CIRCULAR 293 

COAL RESOURCES OF THE UNITED STATES 

(A progress report, October 1, 1953) 

By Paul Averitt, Louise R. Berryhill, and Dorothy A. Taylor 

REPRINTED 1960 

Washington, D. C., 1953 

Free on application to the Geological Survey, Washington 25, D. C. 

Abstract ................................... . 

Introduction .............................. ; .. . 

Status of available> information ............... . 

Methods of preparing and reporting 

coal reserve estimates ................... . 

Classification according to 

characteristics of the coal. ........... . 

Rank of coal ..................... . 

Grade of coal .................... . 

Weight of coal . . . . . . . . . . . . . . . . . .. . 

Thickness of beds ................. . 

Areal extent of beds ............... . 

Thickness of overburden ........... . 

Classification according to relative 

abundance of information ............. . 

Measured reserves ................ . 

Indicated reserves ........... , .... . 

Inferred reserves ................ . 

Distinction between original, remaining. 

and recoverable reserves ............ . 

Original reserves ................ . 

Remaining reserves . . . . . . . . . . . .. . 

Recoverable reserves . . . . . . . . . . .. . 

Percenta,ge of coal recovered in mining ... . 

Underground mining ............ ~ .. . 

Strip mining ..................... . 

Distribution of reserves in selected categories .. 

Distribution according to rank .......... . 

Distribution according to reserve 

categories other than rank ............ . 

Distribution according to 

thickness of overburden ......... . 

Distribution according to relative 

abundance and reliability 

of information ..............•.... 

Distribution according to 

thickness of coal . . . . . . . . . . . . . .. . 

Distribution in all categories ...... . 

Coking -coal reserves ....................... . 

Stripping-coal reserves ..................... . 

CONTENTS 

Page 

1 

3 

3 

6 

6 

6 

7 

7 

7 

11 

11 

11 

11 

12 

12 

12 

12 

12 

12 

12 

12 

13 

13 

13 

16 

16 

16 

16 

16 

16 

18 

Production of coal in the United States ........ . 

State estimates ......................... , ... . 

Arkansas ............................ . 

Colorado ............................. . 

Georgia ............................. . 

Illinois .............................. . 

Indiana .............................. . 

Kansas .............................. . 

Bituminous coal ................. . 

Lignite ..................... , ... . 

Maryland ............................ . 

Michigan ............................ . 

Missouri ............................ . 

Montana ............................. . 

New Mexico .......................... . 

North Carolina ....................... . 

North Dakota ........................ . 

Ohio .. , .............................. . 

Pennsylvania ........................ . 

Bituminous coal ................ . 

Anthracite. ..................... . 

South Dakota ........................ . 

Virginia~ ............................ . 

West Virginia ........................ . 

Wyoming ............................ . 

Other states ......................... . 

Alaska .............................. . 

Possible additional reserves not 

included in estimates .................... . 

Need for additional work ................... . 

United States Coal Commission 

Committee Report, 1922 .................. . 

U. S. Army Corps of Engineers, 1952 ....... . 

Peat reserves ............................ . 

World coal reserves ....................... . 

Relation of coal in the United States 

to other forms of energy ................. . 

Life expectancy of United States 

fuel reserves . . . . . . . . . . . . . . . . . ......... . 

Selected bibliography ...................... . 

ILLUSTRATIONS 

Page 

19 

19 

19 

19 

21 

21 

22 

23 

23 

24 

24 

25 

25 

26 

27 

29 

29 

30 

31 

31 

32 

33 

33 

33 

34 

36 

36 

36 

36 

37 

38 

38 

39 

39 

45 

47 

Page 

Figure 1. Coal fields of the United States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv 

2. Remaining coal reserves of the United States, January 1, 1953 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2 

3. Heat value of coal of different ranks compared to proximate analyses.......................... 8 

4. Remaining coal reserves of the United States, January 1, 1953, by states, 

according to tonnage and heat value....................................................... 10 

5. Percentage distribution of estimated original coal reserves in 16 selected states, according 

to (A) rank; and in 10 states, according to (B) thickness of overburden, (C) relative abundance 

of reliable information available for making estimates, and (D) thickness of coal . . . . . . . . . . . . . . 15 

6. Summary of percentage distribution of estimated original coal reserves 

in 10 selected states . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 17 

7. Distribution of coal production in the United States during 1950 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 

8. Annual supply of energy from mineral fuels and water power in the United States, 1899-1952. . . . . . . . 41 

9. Percentage of total energy supplied by mineral fuels and water power, 1900-1952. . . . . . . . . . . . . . . 42 

Table 1. 

2. 

3. 

4. 

5. 

TABLES 

Coal reserves of the United States, January 1, 1953, by rank ................................ .. 

Coal reserves of the United States, January 1, 1953, by states ............................... . 

Classification of coals by rank. . .......................................................... . 

Estimated coal reserves of the world by continents and principal coal-producing countries ...... . 

Total estimated recoverable mineral-fuel reserves of the United States, January 1, 1953 ....... . 

iii 

Page 

4 

5 

9 

40 

44 
<" 

EXPLANATION 

-

~ 

-

~ 

Anthracite 

and semionthrocite 

Low-volatile 

bituminous cool 

Medium- and high-volatile 

bituminous cool 

Subbituminous coal 

lmmmg) Lignite 

' i 

~ ~ ~----- --""\,. ~ , l 

, 

.. Y". .. --..... ~ ~ / ' ~· \ 

o· :----l ~ ' ~ \ eJ &? I~ ~ , • \ .:, ' ~~ • I I'" .. ~~ f) l;i 1 ~ .. 

~~ op:=- ) I I '----, I ----\ I \ I n'"c ----.. ' 

' 

__.,. ... --... --... , .. , 

... , 

'\, .. 

\' ,--'-. 

'J '~ CO! 

I 

... , o 200 400 600 Miles ,..... 

Figure 1. -Coal fields of the United States. 
COAL RESOURCES OF THE UNITED STATES 

(A progress report, October 1, 1953) 

By Paul Averitt, Louise R. Berryhill, and Dorothy A. Taylor 

ABSTRACT 

As estimated in this second progress report, 

the coal reserves of the United States remaining 

in the ground on January 1, 1953, total 1, 899,739 

million tons. This figure is about a 20 percent reduction of the total estimate published in the first 

progress report (Averitt and Berryhill, 1950). The 

new total is based on new, detailed, conservative estimates of reserves in Indiana, Michigan, Montana, 

New Mexico, North Carolina, North Dakota, South 

Dakota, Virginia, and Wyoming, prepared since 1947 

by the U. S. Geological Survey; on new provisional, 

but equally conservative estimates of reserves in 

Colorado, Maryland, and Ge.orgia, based on previous 

work of the U. S. Geological Survey and other agencies; 

on estimates of reserves in Illinois, Kansas, Pennsylvania, and West Virginia, prepared by the geological 

surveys of those States; and on older and incompletely 

documented estimates for the remaining states. 

The older estimates were prepared on a highly 

generalized basis and were intended to represent total 

possible reserves in both thick and thin beds and under 

both light and heavy overburden. The recent estimates 

have been prepared on a more conservative basis than 

the older estimates and tend to be considerably smaller. 

New conservative estimates have now been prepared 

for 16 coal-bearing States, which include about twothirds of the total estimated reserves of the United 

States. As new estimates are prepared for the remaining States a further reduction of the total reserve 

figure is in prospect, though the reserves still will 

be large. 

The estimated recoverable reserves of the 

United States as of January 1, 1953, total 949, 870 million tons, based on the assumption that half of the 

coal reserves in the ground will be tost in mining, 

and half will be recovered. The distribution of the 

remaining and recoverable reserves by rank is shown 

in the accompanying table. 

The reserves in 10 States have been classified in 

considerable detail according to thickness of beds, thickness of overburden, and relative abundance of reliable 

information available for making estimates. In these 

States, which are representative of several coal provinces, and contain about 40 percent of the total reserves, 

and are thus typical of the United States as a whole, 

5 percent of the total is measured reserves in beds 

28 inches or more thick, and less than 1, 000 feet below 

the surface; and 20 percent is indicated reserves within 

the same limit of thickness and less than 2, 000 feet 

below the surface. The remaining 75 percent is inferred 

reserves, reserves in thin beds, and reserves 2, 000 to 

3, 000 feet below the surface. 

The large percentage of inferred reserves obviously 

includes some coal in thick beds, which for lack of detailed information cannot be appraised quantitatively. 

Although accurately based on the data now available, the 

distribution percentages are subject to considerable change · 

as new work is completed, particularly in the transfer of 

reserves from the indicated and inferred categories to 

the measured category. The figures serve, however, to 

indicate the present state of knowledge of the Nation's coal 

reserves, and they point to the need for additional geologic 

mapping and exploration. 

Remaining coal reserves of the United States, January 1, 1953 

Estimated total Estimated recoverable reserves, reserves remaining 

Rank in the ground, January l, 1953, assuming 

January l, 1953 50 percent recovery 

(In millions of (In millions of (In quadrillions 

short tons) short tons) of Btu) 

Bituminous coal---------------------------- 1,049,457 524,729 13,643 

Subbituminous coal------------------------- 372,934 186,467 3,543 

Lignite------------------------------------ 463,356 231,678 3,105 

Anthracite and 

semianthracite--------------------------- 13,992 6,996 178 

Total--------------------------------- 1,899,739 949,870 20,469 

1 
C\:) 

"'./'• / \ I "'\ A._l ____________ ir-------------]. --,~· .. · ....... ---_T_, I :J ... '-----... """--'". · ,~-\~~\ I, -- ._ , - , , , , I \ ' ' i '1 I 

L2J 

BS 

', L~~--------1_ ' ' . I ' . I \ ) ~ \-.l--' :..-- - I ' J (_~ B . ,_____ ' ----~ \ ~ I -- ~ . 

/ = 1 , !t: -- ""'--- ' \ c---------~ L ' '\. ' , --.~ { }8P ' ----"; ' ' __ \C7 {;', ' 

I I I I -----, • ' ' C7 I -- , --- --"\-- . ~~ - ------ ' . ' -------------· "\ - ' -- - -r·--·----1_ __ --,. ____ ; 1 : \ ~ -' '\ 1

\ j ~1{\_ ' 1 L I ' §II ; ' ' / I l :_T--------: ___ \::--~----1 I \I )-~- !' t ~ ', : I 1 /---- ( \__ ,I ' \.,_...r A ---

\ I s : : : ~ f-,.r/ / --- \ · I I ~·1 ',"_J ------,../ C7 

\ 

' 

0 

A 

0 

L L__.--- j /.J _ B' ' ' -----< __ , 'i ,., .... - ... _' ' '• --- I -- 1 I ..- ., LZ::Z7 , I -----t--------,-1____ . r- ......, __.~.---~...... BSL \ ! gjj '------., I \ { ---\CJ '\ 

\[ p I dlJJ i i :,=ABL /,--,1 '\ --\ \ 

' A o ' ' ' 

I I ''-..... ' ' ' ' I ---------------, ____ II I { 

•c::.c;::,o 

II. 

~ 

EXPLANATION 

( ' ~ I \ I ,. __ _) : ' ' ' __, 

~........._ -------------___.___~ , I ~--~----- '-, J ~ \ ) 'C L__ I \ .. ----"'~-- lliJ Anthracite and semionthrocite '"'-, A \,_ ,,---"""' I Bituminous cool 

B 

~ Subbituminous cool 

s 

[]I Lignite 

L 

'\..._, I 

'\ \ '-......_ __ 

50fT\ 

0

i.J) Billion short tons 

p· 

L7 Less thon one billion tons 0 200 400 600 Miles -:. ... , ... -· 

Figure 2. -Remaining coal reserves of the United States, January 1, 1953. 
A comparison on a uniform Btu basis of reserves 

of coal and other fuels shows that coal constitutes 

84 percent of the total estimated recoverable fuel reserves, and that petroleum and natural gas each constitute about 2 percent. The remaining 12 percent is 

oil in oil shale, which is not currently used as fuel. The 

disparity in reserves is further emphasized by the fact 

that petroleum and natural gas together are being produced and consumed at a rate about equal to that of coal. 

The total recoverable reserves of coal as of 

January 1, 1953, are 1, 279 times the recent average 

annual production. Even assuming a great increase in 

the rate of coal production, these reserves still will 

last many generations. On any basis of analysis the 

coal reserves of the United States are very large and 

give comforting assurance that the fuel needs of the 

Nation can be met in any contingency for many decades 

to come. 

INTRODUCTION 

The industrial supremacy of the United States is 

based largely on the abundance and accessibility of the 

three mineral fuels, coal, petroleum, and natural gas, 

of which coal is by far the most abundant. Although 

the total reserves of coal in the United States are known 

only in a general way and the total reserves of petroleum 

and natural gas are largely undefined, and may ultimately 

prove to be much larger than present estimates suggest, 

it appears on the basis of information currently available that the recoverable reserves of coal are of the 

order of 22 times greater than the combined reserves 

of petroleum and natural gas. In spite of this marked 

difference in relative magnitude of reserves, petroleum 

and natural gas do not at present differ greatly in cost 

from coal, and they are generally more convenient to 

use. As a result, the four-fold increase in use of 

energy in the United States that has taken place during 

the last 50 years has been met largely by an increase 

in the use of petroleum and natural gas. The increase 

has been accelerated in recent years by the extraordinary demands of World War II, and by a considerable increase both in population and in per capita use 

of energy, to such an extent that the present use of 

petroleum and natural gas now exceeds anything contemplated only a few years ago. 

With the increase in use of petroleum and natural 

gas has come a growing realization that the ultimate 

reserves of these fuels have finite limits, and that regardless of where the limits may be established, the 

inevitable day of depletion is being approached at an 

accelerating rate. At some time in the future, therefore, the far larger reserves of coal must be drawn 

upon in increasing quantities to supply some of the 

needs now served by petroleum and natural gas. The 

growing interest in coal is based largely on the general 

belief in our ultimate dependence on coal as a fuel, and 

on the assurance that coal can be adapted to meet practically all fuel requirements. 

Although coal-bearing rocks cover 14 percent of 

the total area of the United States (fig. 1), and contain 

enormous reserves, it is apparent that reserves of 

coal also have limits. In the extensively mined eastern 

coal fields, it is becoming increasingly difficult to locate new areas containing thick beds of high-rank and 

high-quality coal to replace areas that have been mined 

out. This is particularly true in areas containing 

3 

low-volatile bituminous coal, which is so important in 

the manufacture of coke, and which constitutes only 

about 1 percent of the total reserves. Furthermore, 

a considerable part of the total reserves of the United 

States consists of coal of lignite and subbituminous 

ranks, or of thin coal beds that can be mined only with 

great difficulty and expense, or of reserves that must 

be classed as inferred for want of sufficient information 

about their occurrence and extent. 

Considering the importance of coal in the present 

and future fuel economy, it is apparent that much more 

information is needed about the distribution of coal in 

the United States than has been available in the past. 

Recognizing this need, the U. S. Geological Survey 

began in 1947 to expand the program of detailed geologic 

mapping in coalfield areas, and simultaneously started 

the preparation of new state by state summary estimates 

of coal reserves. Several state geological surveys have 

embarked on reserve programs in the individual states. 

The increasing volume of geologic data available on the 

occurrence of coal, and the detailed and careful methods 

now employed in calculating and classifying coal reserves, 

already permits a much more reliable and useful estimate 

for the coal reserves of the United States than has previously been available, although much detailed and summary 

work remains to be done to improve the accuracy 

and completeness of the estimate. 

This second report of progress on the results 

of the program to reappraise the coal reserves of the 

United States supersedes "Coal resources of the 

United States, a progress report, November 1, 1950," 

published as U. S. Geological Survey Circular 94 in 

December, 1950. 

STATUS OF AVAILABLE INFORMATION 

Summary estimates of coal reserves are based 

largely on detailed geologic maps showing the outcrops 

and correlations of the individual coal beds, and on 

accompanying geologic reports giving detailed measurements of the coal thickness. This information is augmented locally by data from exploratory and development drilling and from operating mines. Unfortunately, 

many coal-bearing areas in the United States have not 

been mapped geologically;· many others have been 

mapped only in reconnaissance; and few have been 

prospected other than along the outcrops of the beds. 

In states where recent reserve appraisals have been 

prepared, many large areas known to be coal-bearing 

have been omitted from consideration for want of information. In Wyoming, for example, 53. 5 percent 

of the coal-bearing areas was thus omitted, and in 

Montana, 9. 3 percent was omitted. Even in the eastern fields where information generally is considered 

to be more abundant, much of the geologic mapping dates 

from the period 1900-1920 and does not provide the data 

necessary for a modern inventory of reserves. Progress 

toward full knowledge of the coal reserves of the 

United States depends, therefore, upon anactive program of detailed geologic mapping and exploratory drilling. 

Such detailed work is in progress on a modest scale by 

the U. S. Geological Survey and several State agencies. 

Based as they are upon the accumulated detailed 

information that is obtained only by the laborious processes of mapping outcrops of coal beds and drilling 

holes to test the coal thickness, summary estimates 

of coal reserves are only proqisional estimates and 
Table 1. -Coal reserves of the United States, Janual"Y 1, 1953, by rank 

(In millions of short tons) 

State 

2 

Alabama ----------------------------------------------

Arkansas --------------------------------------------- COLORAD03---------------------------------------------

GEORGIA ----------------------------------------------

ILLINOIS --------------------------------------------- INDIANA ----------------------------------------------

Iowa -------------------------------------------------

KANSAS -----------------------------------------·------ Kentucky 

MARYLAND 

MICHIGAN 

Reserves depleted to Jan. 1, Recoverable 1953 

Estimated Production plus Remaining reserves 

original loss in mining, reserves Jan. 1, 1953, 

reserves Production 1 assuming past Jan. 1, 1953 assuming 

losses equal 50 percent 

production recovery 

Bituminous coal 

67,570 861 1,722 65,848 32,924 

1,396 84 168 1,228 614 

90,258 367 734 89,524 44,762 

4 wo ~ ~ % ~ 

137' 321 5 156 5 312 137' 009 68' 504 

37,293 1,039 2,078 35,215 17,607 

29,16') 348 696 28,464 14,232 4 20,774 5 6 512 20,762 10,381 

123,327 2,177 4,354 118,973 59,487 4 1,200 5 2 5 4 1,196 598 

297 6 46 1 77 220 110 

Missouri --------------------------------------------- 79,362 267 534 78,828 39,414 

MONTANA ---------------------------------------------- 2,363 32 64 2,299 1,149 

NEW MEXICO -------------------------------------------- 10,948 90 180 10,768 5,384 

NORTH CAROLINA ---------------------------------------- 112 1 2 110 55 

Ohio -------------------------------------------------- 86,584 1,806 3,612 82,972 41,486 

Oklahoma ---------------------------------------------- 54,951 166 332 54,619 27,309 

PENNSYLVANIA ------------------------------------------ 75,093 7,718 15,436 59,657 29,829 

Tennessee --------------------------------------------- 25,665 340 680 24,985 12;493 

Texas ------------------------------------------------- 8,000 11 22 7, 978 3, 989 

Utah -----,--------------------------------------------- 88,184 215 430 87,754 43,877 

VIRGINIA ---------------------------------------------- 11,696 599 1,198 10,498 5,249 

Washington -------------------------------------------- 11,413 126 252 11,161 5, 581 

WEST VIRGINIA ----------------------------------------- 116,618 5,428 10,856 105,762 52,881 

WYOMING ----------------------------------------------- 13,235 247 494 12,741 6,371 

Other states ------------------------------------------~----~~8~2~0~------~~~5-------..~~l~O~--~~T.7~8~l~0~----~~~4~os·~ Total ------------------------------------------ 1,093, 740 22,149 44,2133 1, 049,457 524,729 

Subbituminous coal 

Lignite 

90 

Anthracite and semianthracite 

230 10 20 

713 6 12 

6 1 2 

22,805 5,043 10,086 

355 10 20 

23 0 0 

24,132 5,070 10,140 

Total, 

all ranks----------------------------------- 1,955,294 1,899, 739 13 

27,785 55,555 

'Production, 1800 through 1885, from The first century and a qutJrter of American coal industry, by H. N. Eavenson, privately printed, Pittsburgh, 1942; production, 1886 through 1952, from 

U. S. Geol. Survey Mineral Resources volumes and U. S. Bureau of Mines Minerals YearbOoks, unless otherwise indicated. · 2Rese.rve estimates of states in lowercase letters were prepared by, or uoder the direction of, M. R. Campbell prior to 1928. 3 Reserve estimates of states in capital letters supersede earlier estimates by M. R. Campbell. 4 Remaining reserves, January I, 1950. 5 Production, 1950 through 1952. 8 Production, 1860 through 1949, Michigan Geological Survey Division, as cited in U.S. Geol. Survey Circular 77, p. 56, 1950. 7 Past losses assumed to be 40 percent of coal originally in the ground. 8 Includes Arizooa, California, Idaho, and Oregon-. 9

Small reserves and production of lignite included under subbituminous coal. 10Includes Mizooa, California, and Oregon. 11Negligible, (for Kansas see discussion in text). 121ncludes California and Louisiana. 13Somewhat less than total recorded production. See footnote 5. 

4 

45 

949,870 
Table 2.--Coal reserves of the United States, January 1, 1953, by states (In millions of short tons) 

Estimated original reserves Reserves depleted to Jan. 1, ~~ 

State 

Alabamaz---------------------------------------

Arkansas -------------------------------------- COLORAD03--------------------------------------

GEORGIA ----~--------------------------------­

ILLINOIS --------------------------------------

INDIANA --------------------------------------- Iowa ------------------------------------------ KANSAS ---------------------------------------- Kentucky 

MARYLAND 

MICHIGAN 

Missouri -------------------------------------- MONTANA --------------------------------------- NEW MEXICO ------------------------------------ NORTH CAROLINA --------------------------------

NORTH DAKOTA ---------------------------------- Ohio ------------------------------------------ Oklahoma --.------------------------------------

PENNSYLVANIA ---------------------------------- SOUTH DAKOTA ----------------------------------

en Tennessee ------------------------------------- Texas ----------------------------------------- Utah ------------------------------------------ VIRGINIA --------------------~----------------­

Washington ------------------------------------

WEST VIRGINIA --------------------------------- WYOMING -------------------------------------- Other states-----------------------------------

Total -------------------------------------

Bituminous 

coal 

67,570 

1,396 

90,258 

100 4

137.321 

37,293 

29,160 4 20,774 

123,327 

4 1,200 

297 

79.362 

2,363 

10,948 

112 

86,584 

54,951 

75,093 

25,665 

8,000 

88,184 

11,696 

11,413 

116,618 

13,235 

10 820 

1,093.740 

Sub bituminous 

coal 

9,437 

Lignite 

9.0 

( 6) 

1 Production, 1800 through 1885, from The first century and a quarter of American coal industry, by H. N. Eavenson, privately printed, 

Pittsburgh, 1942; production, 1886 through 1952, from U. S. Geol. Survey Mineral Resources volumes and U. S. Bureau of Mines Minerals Yearbooks; 

unless otherwise indicated. 2 Reserve estimates of states in lower case letters were prepared by, or under the direction of, M. R. Campbell prior to 1928. 3 Reserve estimates of states in capital letters supersede earlier estimates by M. R. Campbell. 4 Remaining reserves, January 1, 1950. 6 Production, 1950 through 1952. 8 See discussion in text. 7 Ptoduction, 1860 through 1949, Michigan Geological Survey Division, as cited in U.S. Geol. Survey Circular 77, p. 56, 1950. 

Anthracite and 

semianthracite 

230 

713 

6 

22,805 

355 

23 

24,132 

Total 

67,570 

1,716 

100,408 

4 100 

137.321 

37,293 

29,160 4 20,774 

123,327 

4 1,200 

297 

79,362 

222,047 

61,755 

112 

350,910 

86,584 

54,951 

97,898 

2,033 

25,665 

31,000 

93.340 

12,051 

63,878 

116,618 

121,554 

16,370 

1,955,294 

1

roduction plus oss in mining, 

Production 1 assuming past 

losses equal 

production 

861 1,722 

94 188 

484 968 

12 24 5

156 5 312 

1,039 2,078 

348 696 

56 5 12 

2,177 4,354 52 54 

7 46 8 

77 

267 534 

164 328 

123 246 

1 2 

77 154 

1,806 3,612 

166 332 

12,761 25,522 

1 2 

340 680 

62 124 

218 436 

609 1,218 

145 290 

5,428 10,856 

383 766 

9 18 

13 

27,785 55.555 

8 Past losses assumed tO be 40 percent of coal originally in the ground. 

•small reserves and production of lignite included under subbituminous coal. 10Includes Arizona, California, Idaho, and Oregon. 11 Includes Arizona, California, and Oregon. 12 Includes California and Louisiana. 10 Somewhat less than total recorded production. See footnote 5. 

Remaining 

reserves 

Jan. 1, 1953 

65,848 

1,528 

99,440 

76 

137,009 

35,215 

28,464 

20,762 

118,973 

1,196 

220 

78,828 

221,719 

61,509 

110 

350,756 

82,972 

54,619 

72,376 

2,031 

24,985 

30,816 

92,904 

10,833 

63,588 

105,762 

120,788 

16,352 

1,899.739 

Recoverable 

reserves 

Jan. 1, 1953 

assuming 

50 percent 

recovery 

32,924 

764 

49,719 

38 

68,504 

17,607 

14,232 

10,381 

59,487 

598 

110 

39,414 

110,860 

30,754 

55 

175.378 

41,486 

27,309 

36,189 

1,015 

12,493 

15,438 

46,452 

5,417 

31,794 

52,881 

60,395 

8,176 

949,870 
are subject to change as mapping, prospecting, and 

development are continued. Such estimates are valuable, 

however, in showing the quantitative distribution of 

reserves, in selecting areas favorable for further 

exploration or development, and in planning industrial 

expansion. 

The first considered estimate of the total coal reserves of the United States was prepared by M. R. Campbell 

of the Geological Survey, and published at various times 

in the period prior to 1928. For more than 20 years 

this estimate served as the principal reference on our 

National coal reserves and was republished with only 

minor modifications by other individuals and organizations. Campbell's generalized estimate was necessarily 

based on many assumptions concerning the thickness 

and lateral extent of coal beds in areas for which little 

geologic data were then available. The estimate included all coal in the ground in beds more than 14 inches 

thick under less than 3, 000 feet of overburden, without 

attempting to distinguish between reserves of thick, 

easily-accessible coal and reserves of thin, deeply 

buried coal. 

In the period 1928 to 1947 summary reappraisals 

of the coal reserves in Pennsylvania, West Virginia, 

and Kansas were prepared by the Geological Surveys 

of the respective States. 1 These estimates were more 

conservative and more detailed than the older estimates, 

and were correspondingly more useful. 

In the current U. S. Geological Survey program 

to reappraise the coal reserves of the United States, 

primary emphasis is being placed on the amounts of 

coal in separate categories according to rank, thickness of beds, thickness of overburden, and relative 

abundance of reliable data available for preparing the 

estimates, because of the obvious need for such classified information in the proper utilization of our reserves. 

Prepared as part of this program to date are detailed 

reappraisals of the coal reserves in Indiana, Michigan, 

Montana, New Mexico, North Carolina, North Dakota, 

South Dakota, Virginia, and Wyoming, which have been 

presented previously in separate publications; and new 

provisional appraisals of reserves in Colorado, Mary land, 

and Georgia, based on previous work of the U. S. Geological Survey and other agencies. In this same period 

the Illinois Survey has prepared a new and detailed appraisal of Illinois reserves; and the Bureau of Mines 

began a program to appraise the minable reserves of 

coking coal, which to date has yielded reports on reserves in 11 counties in Pennsylvania, West Virginia, 

and eastern Kentucky. 

The tables included in this circular are based on 

reserve figures from these varied sources, which are 

not strictly comparable. (See tables 1 and 2, andfig. 2.) 

In particular, the Campbell estimates and those for 

Missouri and Ohio, prepared under Campbell's direction quring the same period,2 were based on more 

generous assumptions than the recent estimates, and 

allowance should be made for this fact in considering 

t.hem. Although the figures presented for individual 

states are not strictly comparable, they are cited as 

originally given by the authors, for, to alter them 

arbitrarily by some purely mathematical method for 

use in this progress report would be unnecessarily 

confusing, particularly in view of the fact that revision 

1 References cited under discussion of reserves in individual states. 2 These estimates are opposite state names in lowercase letters 

in tables I and 2 and figure 4. 

6 

of the estimates in some of these states is now in progress or contemplated for the immediate future. 

METHODS OF PREPARING AND REPORTING COAL 

RESERVE ESTIMATES 

In preparing state-wi-de summary estimates of 

coal reserves, all available information is first gathered 

together and recorded on individual coal bed maps. 

Sources of information include the publications and 

records of the U. S. Geological Survey and state geological surveys, maps and drill records of coal mining 

companies, information in the files of state mine inspectors and railroad companies, records of exploration for petroleum and natural gas, records of waterwell drilling companies, and occasionally, private records obtained from individuals. To translate this information accumulated from geologic observation, 

mining, and drilling into estimates of tonnage a series 

of definitions, procedures, and assumptions must be 

employed. 

For practical purposes, two cut-off points must 

be established in calculating coal reserves-one at the 

minimum thickness of coal included in the estimate, 

and another at the maximum thickness of overburden 

allowed above the coal. A very conservative estimate 

may include only the original reserves in thick beds 

and under slight overburden-in other words, reserves 

that could be recovered profitably under current mining 

conditior1.2. A more inclusive estimate, on the other 

hand, may consider thinner, more impure, and more 

deeply buried coal as recoverable by improved methods 

when more easily mined deposits have been exhausted .. 

Other factors, in addition to those involving thickness of coal beds and of overburden, must be established in calculating coal reserve estimates. The 

weight or specific gravity of the coal must be determined or assumed, and where the continuity of a coal 

bed is unknown, a method must be selected to estimate 

its probable extent, based on the available outcrop, 

mine, or drill data. 

The way in which these factors are treated can 

vary greatly with individual estimators, and the results of such varied treatment are apparent in the 

estimates for several states. For this reason, an 

estimate of coal reserves has meaning only when considered in relation to the methods used in obtaining it. 

In order to produce reasonably uniform results 

in preparing coal reserve estimates, the U. S. Geological Survey has adopted a set of definitions, procedures, and assumptions for use by Survey coal 

geologists. These definitions, procedures, and 

assumptions, which are discussed in paragraphs 

below, were prepared jointly by members of the 

Geological Survey and the Bureau of Mines, and include recommendations of the National Bituminous 

Coal Advisory Council. 

Classification according to characteristics of the coal 

Rank of coal. -Coal is classified by rank. according to percentage of fixed carbon and Btu content, 

calculated on a mineral-matter-free basis. As shown 

in figure 3, the percentage of fixed carbon and the Btu 

content, except in anthracite, increase from the lowest 

to the highest rank of coal as the percentages of 
volatile matter and moisture decrease. The decrease 

in volatile matter and moisture, and the accompanying 

increase in fixed carbon took place progressively during the slow process by which plant material deposited 

in swamps and marshes in the geologic past was transformed into coal. The lower layers of plant material 

in the swamps were first compacted under successive 

layers of vegetation. Later, as the sea covered the 

coal swamps, the weight of sediments deposited on the 

sea floor further compressed the plant material and 

caused successive reductions in the amounts of volatile 

matter and moisture. That these changes are profound 

is evidenced by the fact that a foot of bituminous coal 

may contain the accumulated plant growth of several 

centuries. Locally, deformation of the coal-bearing 

sediments by movements of the earth's crust speeded 

up the coal-forming process. 

Rank of coal is thus a function of age and deformation, and is a way of expressing successive stages 

in the formation of coal. It is quite independent of 

grade, or quality, which is in part a function of the ash 

and sulfur in the coal. 

The standard classification of coal by rank in use 

in the United States is that established by the American 

Society for Testing Materials (1939). This classification, 

which is reproduced as table 3, is used uniformly in 

classifying all coal reserve estimates. As coals of 

different rank are adaptable to different uses, rank is 

the major basis of differentiation shown in figures 1 

and 2 and in tables 1 and 2. 

Most of the tables and illustrations in this report 

show reserves of all ranks of coal in short tons as computed. In terms of ultimate usefulness, however, comparison of the reserves of lignite and subbituminous 

coal, which have relatively low heat values, with reserves of bituminous coal and anthracite, which have 

higher heat values, can best be made on a uniform 

Btu basis. Such a comparison is presented in figure 4, 

which shows the remaining reserves in each state as 

of January 1, 1953, on both a tonnage and a Btu basis. 

Grade of coal. -Coal is classified by grade, or 

quality, largely according to the content of ash, sulfur, 

and other deleterious constituents. Thus far in work 

on coal reserves it has not been possible to report on 

reserves in categories according to grade because the 

number of available coal analyses is small compared 

to the total reserves, and because the analyses are 

concentrated for the most part in areas of active mining 

and limited to the line of outcrop of certain key beds. 

Although the definitions and procedures used in 

calculating coal reserves generally permit the inclusion 

of beds containing as much as 33 percent ash, very 

little coal of such high ash content is included in modern estimates, in part, because of the natural conservatism of the estimators, and, in part, because all 

layers of parting and bone more than 3/8-inch thick 

are excluded in determining the thickness of the beds. 

On the other hand, reserve estimates do include beds 

containing somewhat higher ash contents than beds now 

being mined, and the average ash content in the total 

estimated reserves probably is higher than the average 

ash content of existing analyzed samples. 

Fieldner and others (1942) have prepared a list 

of 642 typical mine, tipple, and delivered samples of 

7 

coal from beds in all parts of the United States. In 

this list the ash contents range from 2. 5 to 32. 6 percent, 

and the average ash content is 8. 9 percent. The sulfur 

contents range from 0. 3 to 7. 7 percent, and the average 

sulfur content is 1. 9 percent. 

It is thus apparent that the average ash and sulfur 

contents of the estimated reserves could be markedly 

higher than the average ash and sulfur contents of existing analyses, and still be significantly lower 

than the maximum amounts permitted in coal included 

in reserve estimates. 

Weight of coal. -The weight of coal in the ground 

varies significantly with rank and with differences in 

ash content. The following values, however, conform 

closely to the average of the. recorded specific gravities 

of coal in each of the four major rank categories: 

Rank Specific Tons per Tons per 

gravity acre-foot sq. mile-foot 

Anthracite and. 

semianthracite----- 1.47 2,000 1,280,000 

Bituminous coal------ 1.32 1,800 1,152,000 

Subbituminous coal--- 1.30 1,770 1,132,560 

Lignite-------------- 1.29 1,750 1,120,000 

Where more precise data are not available, these 

values are assigned as the weight of the coal in the 

ground in all recent U. S. Geological Surveyestimates 

of coal reserves. 

Persons closely associated with individual mining operations often employ lower weight factors to 

allow for anticipated losses in mining. Such a practice is not suitable for use in a general report, however, for recoverability may vary greatly in different 

areas, in different beds, and with different methods 

of mining. The selected weight factors, therefore, 

are intended to yield reserves of coal in the ground 

without regard to ultimate recoverability. 

Thickness of beds. -According to the present 

procedures of the U. S. Geological Survey, coal reserves are calculated and reported by beds in categories of thickness as follows: 

Rank 

Anthracite, semianthracite, 

and bituminous coal----------

Subbituminous coal 

and lignite------------------

Thickness categories 

More than 42 inches. 

28 to 42 inches. 

14 to 28 inches. 

More than 10 feet. 

5 to 10 feet. 

2-! to 5 feet. 

A few of the recent estimates are classified into 

thickness categories of 14 to 24 inches, 24 to 36 inches, 

and more than 36 inches for bituminous coal. Other 

estimates made at various times have used 18 inches 

as the minimum thickness of bituminous coal. Such 

differences are noted under the discussion of reserves 

in individual states as an aid in making comparisons 

between estimates. 

The thickness of a coal bed is evaluated wherever 

possible by the use of isopach lines. Generally, however, the data are insufficient for this purpose, and 

average figures, which are weighted according to the 
1-:Ij 

<.0" 

8 

(D 

~ 

I 

t:r1 

(D 

p:l 

rt-

<: 

p:l 

~ 0 

...... 

0 

0 

~ 

0 

...... 

8: 

...... 

...... 

(D 

1-j 

([> 

CXl ~ rt1-j 

p:l 

~ 

Pi"' 

Ul 

0 

0 

s 

'0 

p:l 

1-j 

(D 

0. 

rt0 

'0 

1-j 

0 

:>< 

§" 

~ ([> 

p:l 

~ 

-<' Ul 

(D 

?1 

I') 

0 0 

Lianit 

-

I I -n \ 

Subbituminous C ' 

I SubbitumLu-:- B 

I . I X 

Subbttummous A 

I 

H. 19 h -volattle I. ~ C 

bituminous 

~ 

0 

\ 

\ 

\ 

L 

0 

I 

I 

I 

I 

l 

I 

I 

i 

('" 

(1) 

0 

' 

17 

' ' ' ' ' 

...A 

......... 

(" 

I 

I 

\ 

()) 

0 

\ 

\ 

\ 

\ 

\ 

I 

I 

I 

I 

I 

\ 

\ 

s: 

0 -

(j) 

-; 

c 

:::0 

rr1 

\ 

-o 

- <D 

O() 

O<D 

3. 

I 

IH h I t ! :b t .I \ (f\ \ 

19 -vo a 1 e 1 ummous 1 \ 

~ 

I H h II tl ()A . I . '\ 

I 

\ 

\ 

\ 

19 -vo a 1 e b1tummous \ \ 

~ 

I M d I )>I . 1. . iv T \ I \ I \ 

e IUm-vo atlle b1tummous ' .. I 

~ 

I Jw-~latile lbituminaul 

', ..A I 

\ I 

' I 

' ..A '. ' ~ 

I I aJSemiJthracite 

' (f'\ \ I 

\ ';0\ \ 

·~ 

I I Althracite 

\ I 

0 I 

I I I I 

\ ! 

~ 

I I z I : 7 I I 

I I 

Meta-anthracite I f 

~ 

0 

N 

0 

0 

0 

~ 

0 

0 

0 

m 

0 

0 

0 

()) 

0 

0 

0 

~(5 

0 

0 

0 

N 

0 

0 

0 

_.f:o 

0 

0 

0 

mcc 

-ooc 

0 
Table 3. Classification of coals by rank a 

Legend: F.C.;.,. Fixed Carbon. V .M. =Volatile Matter. Btu. == British thermal units. 

Class Group 

; 

I 

1. Meta-anthracite ................. 

I 

I 

2. Anthracite ...................... 

I. Anthracitic 

3. Semianthracite .................. 

I 

j 1. Low volatile bituminous coal. ... 

2. Medium volatile bituminous coal. 

II. Bituminousd 

3. High volatile A bituminous coal. 

4. High volatile B bituminous coal. 

5. High volatile C bituminous coal. 

1. Subbituminous A coal. .......... 

III. Subbituminous 2. Subbituminous B coal. .......... 

3. Subbituminous C coal. .......... 

! 

IV. Lignitic I 

1. Lignite ......................... 2. Brown coal ..................... 

Limits of Fixed Carbon or Btu. Mineral-Matter-Free 

Basis 

Dry F.C .• 98 per cent or more (Dry V.M., 2 per cent or less) 

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) 

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 

1 

I 

I 

l 

I 

I 

(Dry V.M ., 31 per cent or I 

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., j 

14,00<f or more ! 

Moistc Btu., 13,000 or more and less than 14,00<Y' 

Moist Btu., 11,000 or more and less than 13,00<f 

Moist Btu., 11,000 or more and less than 13,000e 

! 

Moist Btu., 9500 or more and 

less than 11,00011 ' 

; 

Moist Btu., 8300 or more and: 

less than 95ooe 

Moist Btu., less than 8300 

Moist Btu., less than 8300 

Requisite Physical 

Properties 

K onagg lomera ting b 

Either agglomerating or non weathering/ 

Both weathering an d 

nonagglomerating 

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. e 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. 

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

and nonweathering; Variety 2, agglomerating and weathering; Variety 3, nonagglomerating and nonweathering. 

9 
Billions of short tons 0 

Quadrillions of Btu 1 0 

NORTH DAKOTA 2 

MONTANA 

ILLINOIS 

WYOMING 

Kentucky 3 

WEST VIRGINIA 

COLORADO 

Utah 

Ohio 

Missouri 

PENNSYLVANIA 

Alabama 

Washington 

NEW MEXICO 

Oklahoma 

INDIANA 

Texas 

Iowa 

Tennessee 

KANSAS 

VIRGINIA 

Arkansas 

SOUTH DAKOTA 

MARYLAND 

Other states 4 

100 300 

EXPLANATION 

B~ 

Bituminous coal 

Subbituminous 

~ 

coal 

Ll uu I 

Lignite A_. 

Anthracite and semianthrocite 

Upper bar for each state shows coal reserves by tons; 

lower bar shows coal reserves by Btu 

JJ Conversion factors: anthracite, 12,700 Btu per pound; bituminous cool, 13,000 Btu per pound; subbituminous cool, 

9500 Btu per pound; end lignite, 6700 Btu per pound 

400 

2.1 Reserve estimate of States in capitol letters supersede earlier estimates by M. R. Campbell 

~ Reserve estimate of States in lower case letters were prepared by, or under the direction of M. R. Campbell prior to 1928 

9:1 Includes Arizona, California, GEORGIA, Idaho, Louisiana, MICHIGAN, NORTH CAROLINA, and Oregon 

Figure 4. -Remaining coal reserves of the United States, January 1, 1953, by states, according to tonnage and 

heat value. 

10 
approximate area of bed represented by each observation, are used. If the points of observation are not 

evenly spaced, the weighting is accomplished by assigning intermediate values for the thickness at places 

where data are needed to fill out a system of evenly 

spaced points. Where this procedure is followed to 

obtain the weighted average thickness along the outcrop 

of a persistent bed, the two end points of minimum 

thickness are also included in the average. Where the 

points of observation are fairly evenly spaced, as in 

an exploratory or development drilling program, a 

simple average is deemed sufficient. 

Partings more than three-eighths of an inch thick 

are omitted in determining the thickness of individual 

beds. Beds and parts of beds made up of alternating 

layers of thin coal and partings are omitted if the partings make up more than one-half the total thickness, 

or if the ash content exceeds 33 percent. Benches 

of coal of less than the minimum thicknesses stated, 

which lie above or below thick partings, and which 

normally would be left in mining, are also omitted. 

Occasionally, in older coal-reserve estimates, the 

"modulus of irregularity" has been used to determine the 

probable minimum thickness of a coal bed. According 

to this formula, the probable minimum thickness isobtained by multiplying the average of the measurements 

of bed thickness by (l- ~), in which S is the sum of all 

the thickness measurements and SD is the sum of the 

differences between each individual thickness measurement and the average of all the thickness measurements. 

The modulus of irregularity was originally adopted 

by the U. S. Geological Survey as a mechanism in establishing the value of coal lands (Smith and others, 1913), 

but it is no longer used for this purpose. It was devised 

as a safeguard for the buyer of coal lands in areas 

where the coal beds range in thickness within wide 

limits. Computation of the thickness of the coal by using 

the modulus of irregularity permitted the "thickness 

of the coal under any tract of land to be considered as 

less than the average of the measurements. For while 

the coal is as likely to be just above the average as 

just below, and mathematically, is more likely to be 

just the average thickness than any other, yet a cautious buyer bargaining for coal would always want to 

discount the probability a little as a matter of safety." 

The modulus of irregularity is cumbersome and inappropriate for use in preparing estimates of coal 

reserves. 

Areal extent of beds. -The areal extent of coal 

beds included in recent U. S. Geological Survey reserve estimates is determined in several ways. Where 

the continuity of the bed is well known from maps of 

the outcrop, mine workings, and drill holes, the entire 

area of the known occurrence of the bed is taken, even 

though points of observation are widely spaced. Persistent beds that have been traced around a basin or 

spur are considered to underlie the area enclosed by 

the outcrop. Otherwise, the length of outcrop within 

the thickness limits listed is considered to determine 

the presence of coal in a semicircular area having a 

radius equal to one-half the length of the outcrop. The 

total area of coal is considered to extend beyond such 

a semicircle if mine workings or drill holes so indicate, in which case coal is considered to extend only 

1 mile beyond the limits of the mine workings. An 

isolated drill hole too far removed to be incorporated 

11 

in the area thus defined is considered to determine the 

area of coal extending for a maximum radius of half a 

mile around the hole. 

Recent estimates of other agencies follow these 

or very similar procedures. Minor points of difference 

are noted under discussions of the various states. 

The older estimates assumed much wider continuity for the individual beds, and, in general, this 

is the major reason why the older estimates tend to 

be larger than the recent estimates. 

Thickness of overburden. -Wherever possible, 

the reserve data are reported by the U. S. Geological 

Survey in three classes according to thickness of over- burden, as follows: 

0 to 1,000 feet 

1,000 to 2,000 feet 

2,000 to 3,000 feet 

In some areas where the overburden is thin the reserves have been calculated in several sub-categories 

within the 0 to 1, 000-foot category, whereas in other 

areas one or more major categories have been omitted. 

The tabulation of the reserves according to the thickness of overburden in Indiana and Michigan, for example, 

is in more detail than is suggested in the above table. 

In Indiana all of the estimated reserves are less than 

1, 000 feet below the surface, and strippable coal is 

classified into one of three overburden categories, 

as follows: 

0 to 40 feet 

0 to 60 feet 

0 to 90 feet 

The remainder is considered to be non-strippable coal. 

In Michigan all of the estimated reserves are less than 

400 feet below the surface. Here the measured reserves 

are divided according to thickness of overburden as 

follows: 

50 to 100 feet 

100 to 200 feet 

200 to 300 feet 

300 to 400 feet 

The indicated and inferred reserves in Michigan are 

not classified into sub-categories. In two states, 

Montana and North Carolina, the estimation of reserves 

in the 0 to 1, 000-foot class of overburden was not practicable and, therefore, a 0 to 2, 000-foot class was used. 

Classification according to relative abundance of 

information 

On the basis of the relative abundance of reliable 

data on which the calculations are based, coal reserves 

are reported by the U. S. Geological Survey in three 

classes, known as measured, indicated, and inferred. 

Measured reserves.: -Measured reserves are 

reserves for which tonnage is computed from dime~~ ions 

revealed in outcrops, trenches, minew.Pl'kings, a.nCI drill 

holes. The points of observation and measurement are 

so closely spaced, and the thickness and extent of the 
coal are so well defined that the computed tonnage is 

judged to be accurate within 20 percent or less of the 

true tonnage. Although the spacing of the points of 

observation necessary to demonstrate continuity of coal 

varies in different regions according to the character 

of the coal beds, the points of observation are, in general, about half a mile apart. 

Indicated reserves. -Indicated reserves are reserves for which tonnage is computed partly from specific measurements and partly from projection of 

visible data for a reasonable distance on geologic 

evidence. In general, the points of observation are 

approximately 1 mile apart, but they may be as much 

as H- miles apart for beds of known geologic continuity. 

Inferred reserves. --Inferred reserves are reserves for which quantitative estimates are based 

largely on broad knowledge of th~ geologic character 

of the bed or region and for which few measurements 

of bed thickness are available. The estimates are 

based on an assumed continuity for which there is 

geologic evidence. In general, inferred coal lies more 

than 2 miles from the outcrop. 

Distinction between original, remammg, and 

recoverable reserves 

Coal reserves may be calculated and presented 

according to one or all of three quite different points 

of view as defined below: 

Original reserves. -Original reserves are reserves in the ground before the beginning of mining 

operations. In the calculation of original reserves no 

allowance is made for past production and losses in 

mining or for future losses. Most older estimates are 

for original reserves only. 

Remaining reserves. -Remaining reserves are 

reserves in the ground as of the date of appraisal and 

may be obtained by subtracting past production and 

losses from original reserves. 

Recoverable reserves. -Recoverable reserves 

are reserves in the ground as of the date of appraisal 

that can actually be produced in the future. Much 

coal thus classified can be mined at or near present 

prices, measured in man-hours and equipment. The 

remainder, presumably, can be mined at gradually 

increased prices as the thicker and more accessible 

beds are exhausted. Recoverable reserves are obtained by subtracting estimated future losses in 

mining from remaining reserves. 

The preparation of an estimate of original reserves is essential to the successful determination of 

remaining and recoverable reserves because it provides a base figure from which other figures can be 

derived. An estimate of original reserves, although 

subject to revision with new mapping and exploration, 

is essentially a constant, needing no date nor explanation to make it understandable. From this estimate 

the figur.es for remaining and recoverable reserves, 

which must be dated, can be determined annually, if 

desired, from available information on production 

and losses or from surveys of mined-out areas. 

12 

Coal reserves can be· calculated successfully 

without reference to original reserves only in virtually 

mined-out areas where remaining reserves are small 

and clearly defined. In most coal areas in the United 

States, however, the estimates of remaining reserves 

still closely approximate those of original reserves. 

This is particularly true in the West, where relatively 

little mining has been done. 

In tables 1 and 2, estimates are presented for 

original, remaining, and recoverable reserves as 

a means of emphasizing the distinction between these 

terms. 

Percentage of coal recovered in mining 

For calculating remaining and recoverab~e 

reserves, reasonably accurate figures for the past 

production of coal can be obtained from statistics 

on annual production. The figures for past and 

estimated future losses of coal in mining, also needed 

in these calculations, are not so easily obtained. In 

localities covered by detailed mine maps, past losses 

in mining can be determined by comparing production 

figures with measurements of areas known to be 

mined out. The necessary detailed maps are not 

available, however, for many of the coal-mining 

areas in the United States, and the estimates of 

individuals familiar with local rpining operations 

provide, in general, the only indication of the relative 

tonnages of coal that are recovered and lost in mining. 

The percentage of coal recovered in mining also 

differs greatly in different areas, depending upon such 

factors as the nature of the roof rock and the methods 

used in mining. In calculating remaining and recoverable reserves on a regional or national scale, therefore, an average figure for the estimated percentage 

of recovery in the past and in the future must be 

derived from a consideration of the relatively few 

detailed studies available. 

Underground mining. -Most studies of recoverability in underground mining involve consideration 

of individual mines or small areas, and typically 

indicate a higher recoverability than studies of 

larger areas. In some individual mines, for example, 

as much as 80 or 90 percent of the coal in the block 

actually being mined may be recovered. From the 

total-resource point of view, however, recoverability 

appears to be only about 50 percent of the coal in 

the ground. This marked difference is due to the 

fact that studies of recoverability in larger areas 

include consideration of coal that is left in barrier 

pillars, in restricted areas around oil and gas wells, 

under towns, railroads, roads, and streams, in rider 

beds, in thin and impure beds, and in areas of 

faulting and folding, as well as the more conspicuous 

losses in the block or blocks of coal actually being 

mined. 

The results of an investigation by Cady (1949) 

of the coal resources of Franklin County, Illinois, 

for example, have shown a recovery of less than 

50 percent of the coal originally present in the No. 6 

bed in that county. A similar study by Flint (1951) 

has indicated that the recovery of coal in Perry County, 
Ohio, between 18,38 and 1948 was only 43 percent of the 

amount originally present. In Michigan the recovery 

of coal has averaged about 60 percent of the total coal 

in the ground, according to the estimates of individuals 

familiar with mining operations in the State (Cohee and 

others, 1950, p. 5). B. W. Dyer has stated in a personal communication that, in his opinion, mining operations in Utah have not been able to recover more than 

50 percent of the total coal in the ground. 

Eavenson (1946) has estimated that the actual recovery from the Pittsburgh bed in Pennsylvania is not 

more than 50 to 60 percent because of the large amount 

of coal that is left in the barriers, in reservations for 

oil and gas wells, under buildings, and in the rider above 

the main bed. In calculating the remaining reserves of 

bituminous coal in Pennsylvania, Ashley (1944) assumed 

a recovery of 50 percent for all coal in the State with 

the exception of that in the Pittsburgh bed, for which he 

assumed a recovery of 66-2/3 percent. Ashley's figures were based ·on the percentage recovery of coal in 

Fayette County, Pe1msylvania, as determined by Moyer 

(Hickok and Moyer, 1940). 

The weighted average recovery of bituminous coal 

in 11 counties of the Appalachian Region as determined 

by Dowd and others (1950-52) is as follows: 

Pennsylvania: 

Cambria Co.----------------------------

Indiana Co.----------------------------

Armstrong Co.--------------------------

Westmoreland Co.-----------------------

Fayette Co.----------------------------

Jefferson Co.--------------------------

Kentucky: 

Pike Co.-------------------------------

Floyd Co.------------------------------

Knott Co.------------------------------

West Virginia: 

Raleigh Co.----------------------------

McDowell Co.---------------------------

Recovery 

(percent) 

48.77 

48.95 

46.24 

58.25 

55.41 

51.53 

55.08 

53.23 

53.13 

57.;71 

62.1 

The average of these figures is 53. 67 percent. 

As the results of these recently completed studies 

seem to be in accord, the estimated remaining and recoverable reserves of coal shown in tables 1 and 2 are 

based on the assumption that past mining operations 

have recovered only 50 percent of the coal in the ground 

and that this rate will be maintained in the.future. 

Many individual operations recover more than 50 percent of the coal in the ground, however, and it is to 

be hoped that the general introduction of more efficient 

mining methods will result in a higher average recoverability in the future than the 50-percent factor 

assumed in the preparation of tables 1 and 2. 

As production statistics of separate states generally include only the output of the larger mines, the 

recorded production figures used in tables 1 and 2 

are somewhat less than actual production. Thus the 

past losses in mining, which are assumed in tables 1 

and 2 to be equal to past production, are also somewhat 

less than actual losses. Therefore, the remaining 

and recoverable reserves as reported in tables 1 and 2 

are somewhat higher than they would be if full and 

13 

complete data were available for the amounts of coal 

mined and lost in mining. From a practical point of 

view, a considerable amount of the coal recovered in 

mining is ultimately lost in the process of mechanical 

cleaning. In 1951, for example, 45 percent of the 

bituminous coal produced was cleaned mechanically, 

and an average of 17 percent of this amount was discarded as refuse (U. S. Bur. Mines, 1952, p. 51). 

Strip mining. -According to Koenig (1950, p. 28) 

recoverability in strip mining may, under favorable 

conditions, be as high as 90 percent of the coal originally in the ground. Other operators agree that the 

average recoverability in strip mining is of the order 

of 80 percent, and this figure is used in many appraisals 

of strip mining reserves. Because strippable coal constitutes only a small part of the total reserves, and 

only a modest part of past total production, the use in 

tables 1 and 2 of the 50 percent reCOI.(erability factor 

for all coal appears to be justified. 

DISTRIBUTION OF RESERVES IN SELECTED 

CATEGORIES 

Coal-bearing rocks underly about 14 percent of 

the surface area. of the United States. (See table, p. 14, 

and figure 1. ) These rocks are present in 35 

different states, including a. few, such as Mississippi, 

New York, and Nevada, in which the coal-bearing areas 

are small or the reserves insignificant, and others, 

such as Illinois and West Virginia, in which coal-bearing 

areas represent more than half the total area of the 

states. 

The distribution of reserves on a tonnage basis 

is roughly proportional to the distribution of coalbearing rocks, although a few large areas of coalbearing rocks, like those in Michigan and Texas, contain relatively small reserves; and other areas, like 

some in the Rocky Mountain region, are deeply buried, 

and the contained coal is not included in current estimated reserves. The widespread distribution of accessible coal has contributed greatly to the industrial 

growth of the United States. 

Distribution according to rank 

Although coal is present in many parts of the 

United States, the distribution of reserves of the different ranks is quite unequal. About 60 percent of the 

reserves of the higher rank bituminous coal and anthracite is found east of the Mississippi River, although 

this part of the United States contains only 40 percent 

of the total estimated reserves. West of the Mississippi 

River, reserves of the higher ranks of coal are present 

only in comparatively small quantities, in Arkansas, 

Oklahoma, Colorado, and Washington. The 60 percent 

of the United States reserves west of the Mississippi 

River is mostly lignite, subbituminous coal, or highvolatile C bituminous coal. 

The reserves of lignite and subbituminous coals 

in the West have only local value at present, though it is 

certain that they will have greater usefulness in the future. 

Coals of these ranks tend to crumble during transportation, 

and to ignite by spontaneous combustion if stored for too 

long a period without special precautions. They also have 
Distribution of coal-bearing areas in the United States 

Area underlain of state 1 by Percent underlain by Total area State coal-bearing rocks (sq. miles) (sq. miles) coal-bearing rocks 

Alabama ---------------------------- 51,609 9,700 19 

Arizona ---------------------------- 113,909 3,040 3 

Arkansas ---------------------------- 53,104 1,600 3 

California ------------------------- 158,693 230 0.1 

Colorado --------------------------- 104,247 25,400 24 

Georgia ---------------------------- 58,876 170 0.2 

Idaho ------------------------------ 83,557 500 0.6 

Illinois --------------------------- 56,400 37,700 67 

Indiana ---------------------------- 36,291 6,500 18 

Iowa ------------------------------- 56,290 23,100 41 

Kansas ----------------------------- 82,276 18,8oo 23 

Kentucky --------------------------- 40,395 14,600 36 

Louisiana -------------------------- 48,523 1,360 3 

Maryland --------------------------- 10,577 440 4 

Michigan --------------------------- 58,216 11,600 20 

Mississippi ------------------------- 47,716 1,000 2 

Missouri --------------------------- 69,674 24,700 35 

Montana ---------------------------- 147,138 51,300 35 

Nevada ----------------------------- 110,540 50 --- New Mexico ------------------------- 121,666 14,650 12 

New York --------------------------- 49,576 10 --- North Carolina ---------------------- 52,712 155 0.3 

North Dakota ------------------------ 70,665 32,000 45 

Ohio -------------------------------- 41,222 12,350 25 

:)klahoma ---------------------------- 69,919 14,550 ~l 

Oregon ------------------------------ 96,981 6oo 0.6 

Pennsylvania ----------------------- 45,333 15,000 33 

South Dakota ----------------------- 77,047 7,700 10 

Tennessee -------------------------- 42,244 4,600 ll 

Texas ------------------------------ 267,339 16,100 6 

Utah -------------------------------- 84,916 15,000 18 

Virginia ----------------------------· 40,815 1,940 5 

Washington -------------------------- 68,192 1,150 2 

West Virginia ----------------------- 24,181 16,800 69 

Wyoming ----------------------------- 97,914 40,055 41 

Other states ------------------------ 383,634 0 0 

United States total ----------------- 3,022,387 424,450 14 

-

1 U. S. Bureau of the Census: Statistical abstract of the United States, p. _5, 1951. 

lower heat value than other coals. On the other hand, 

the low rank coals are well suited for the synthetic 

production of gas and liquid fuels, and in many parts 

of the West they can be mined efficiently by stripping 

methods. 

The geographic distribution of the different ranks 

of coal is due principally to differences in geologic age. 

Essentially all the coal in States east of the Mississippi 

River, and in Kansas, Iowa, Oklahoma, and in Arkansas, 

is of Pennsylvanian age; in the Western States, on the 

other hand, essentially all the coal is of Cretaceous or 

Tertiary age. The younger Western coal attains high 

rank only where ~t has been deformed and altered by 

the forces that ac(;ompanied mountain building and the 

intrusion of igneous rock. 

14 

Figure 5A, which shows the percentage distribution of original reserves in the four major categories of rank, is based on the estimated reserves 

in 16 states containing about two-thirds of the total 

estimated tonnage in the United States. These states, 

which are shown in capital letters in tables 1 and 2, 

are those in which detailed reserve estimates have 

replaced the earlier estimates of M. R. Campbell. 

Because so large a proportion of the total estimated 

reserves was used in constructing the diagram, it 

may be considered as being substantially correct 

for the United States as a whole. It should be 

noted that the comparisons shown in figure 5A are 

based on tons. A diagram based on heat value would 

show somewhat shorter columns for subb.ftuminous 

coal and lignite. 
w 

(.!) 

<( 

z 

z 

g 

_j 

~ 0 

tI... 

0 

tz 

w 

u 

0:: 

w 

a.. 

w 

(.!) 

<( 

z 

z 

0 

1-

_. 

~ 0 

tLL. 

0 

tz 

w 

u 

0:: 

w 

a.. 

100.----------------------------. 

DISTRIBUTION IN 16 SELECTED 

STATES ACCORDING TO RANK 

A 

0'---'=>.;:;:;:L_-

Anthrocite Subbituminous 

Bituminous cool Lignite 

cool 

100.----------------------------. 

DISTRIBUTION IN 10 STATES 

ACCORDING TO RELATIVE 

ABUNDANCE OF RELIABLE 

INFORMATION AVAILABLE FOR 

MAKING ESTIMATES 

c 

Measured Indicated Inferred 

cool cool cool 

reserves reserves reserves 

w 

<!> 

<( 

z 

z 

0 

t-

_. 

~ 0 

..... 

LL.. 

0 

tz 

w 

u 

0:: 

w 

a.. 

w 

(.!) 

<( 

z 

z 

0 

..... 

....] 

~ 

~ 

LL. 

0 

..... 

z 

w 

u 

0:: 

w 

a.. 

100~-------------------------, 

DISTRIBUTION IN 10 STATES 

ACCORDING TO THICKNESS 

OF OVERBURDEN 

8 

0-1000 ft 2000-3000 ft 

1000- 2000 ft 

100.---------------------------. 

DISTRIBUTION IN 10 STATES 

ACCORDING TO THICKNESS 

OF COAL 

D 

Thick Intermediate Thin 

Figure 5. -Percentage distribution of estimated original coal reserves in 16 selected states, according to (A) rank; 

and in 10 states, according to (B) thickness of overburden, (C) relative abundance of reliable information available for making estimates, and (D) thickness of coal. 

15 
Distribution according to reserve categories other 

than rank 

Figures 5B, 5C, 5D, and 6 show the percentage distribution of estimated reserves in categories 

other than rank in 10 states, which contain about 

40 percent of the total estimated reserves in the 

United States. These 10 states Illinois Indiana 

Michigan, Montana, New Mexic~, North' Carolina: 

North Dakota, South Dakota, Virginia, and Wyoming, 

are the only ones in which the reserve information is 

classified in sufficient detail to permit conclusions 

about the distribution of reserves in these additional 

reserve categories. The sample presented by the 

10 states is fairly large, however, and the observed 

distribution perc~ntages should show the general order 

of magnitude of distribution for the United States as a 

whole. 

Distribution according to thickness of overburden. -Figure 5B shows the percentage distribution 

of reserves in three categories according to the thickr..ess 

of overburden 0 to 1, 000 feet, 1, 000 to 2, 000 feet, and 

2, 000 to 3, 000 feet. It is noteworthy that 87 percent of the 

estimated reserves in the 10 states is less than 1, 000 feet 

below the surface, and that only 10 percent and 3 percent, 

respectively, are present in the 1, 000 to 2, 000 and 2, 000 

to 3, 000-foot categories. The impressive concentration 

of reserves in the 0 to 1, 000-foot category is due in part 

to the fact that coal-bearing rocks lie near the surface in 

many places,. and in part to the fact that less information 

is available for the more deeply buried beds. Most of the 

coal mined in the United States today, for example, is taken 

from beds less than 1, 000 feet below the surface, and 

only a. small amount is mined from beds 1, 000 to 2, 000 feet 

below the surface. In the United States no significant 

amount of coal is mined from beds more than 2, 000 feet 

below the surface, though in Belgium mining has been 

carried to a. depth of nearly 4, 000 feet below the surface. 

As exploration and development are carried to greater 

depths, it is certain that the total estimated reserves in 

the United States will be considerably increased by the 

addition of reserves in the deeper overburden categories. 

Distribution according to relative abundance 

and reliability of information. -Figure 5C shows the 

percentage distribution of original reserves in the 

measured, indicated, and inferred categories, as defined in earlier pages of this report. Of the large 

tonnage of classified reserves present in the 10 states 

only 6 percent can be classed as measured, and only ' 

27 percent as indicated. The far larger figure of 

67 percent for inferred reserves may be attributed in 

part to the conservative approach adopted in preparing 

the newer estimates of reserves, and in part to the 

fact that positive information about the thickness and 

continuity of coal beds is restricted to a zone a mile 

or so wide along the outcrops. The larger percentage 

of inferred reserves thus reflects the lack of precise 

data for many of the coal field areas. It is, however, 

a convenient method of expressing the amount of coal 

that can be inferred with confidence to be present in 

the fields on the basis of the present geologic information. 

Additional geologic mapping and exploration in any of the 

coal field areas included in this distribution study would 

undoubted~y serve to increase the tonnage of measured 

and indicated reserves, and might also increase rather 

than decrease the tonnage of inferred reserves. 

16 

Distribution according to thickness of coal. -The 

terms 11 thick", "intermediate", and "thin" as used in 

figure 5D refer to coal in three thickness categories, 

which differ for the different ranks of coal. Included 

as "thick" are bituminous coal and anthracite more 

than 42 inches thick, and subbiturninous coal and lignite 

more than 10 feet thick. Included as "intermediate" 

are anthracite and bituminous coal 28 to 42 inches thick, 

and subbituminous coal and lignite 5 to 10 feet thick. 

Included as "thin" are anthracite and bituminous· coal 

14 to 28 inches thick, and subbituminous coal and lignite 2~ to 5 feet thick. The smaller percentage of reserves in the "intermediate" category is due probably 

for the most part to the conservativeness of the appraisers. This is particularly true in the estimation 

of inferred reserves, where little information is available to determine the thickness satisfactorily, and the 

tendency is to assume minimum thicknesses. 

Distribution in all categories. -Figure 6 summarizes the distribution of reserves in the three major 

categories presented in figures 5B, 5C, and 5D. The 

figure clearly shows the preponderance of reserves in 

the 0 to 1, 000-foot category, and the relatively small 

quantities of measured reserves in all categories. Reserves are present in each of the possible 27 categories 

allowed for in figure 6 except the one representirlg 

measured reserves in thin beds 2, 000- to 3, 000-feet 

below the surface. The amounts in several categories 

are less than 1 percent of the total, however, and they 

could not be shown on a diagram of this scale. 

Like figures 5B, 5C, and 5D, figure 6 also shows 

the conservative character of the estimates for the reserves in the 10 selected states. The relatively large 

percentages of reserves in the indicated and inferred 

categories, and the small percentages in the measured 

category are due to a lack of data-r.ot a lack of coal. 

Similarly, the relatively small percentage of coal in 

the 1, 000- to 2, 000-foot category as compared to the 

0 to 1, 000-foot category suggests that the deeper overburden categories contain much larger reserves than 

the estimates show. 

COKING-COAL RESERVES 

Coke is a manufactured product, and in spite of 

the frequent use of the term "coking coal, " there is 

actually little coal that can be used alone to produce 

coke satisfactory for metallurgical processes. Coal 

of medi urn -volatile bituminous rank is best for use in 

coke production, but reserves of coal of this rank are 

small and are rapidly being depleted. Coke that is 

equally satisfactory, however, can often be produced 

by blending together two different ranks of coal. Generally, 15 to 30 percent of low-volatile bituminous 

coal is used in a blend with high-volatile bituminous 

coal that alone produces only an inferior coke. Weakly 

coking coal is sometimes improved by adding small 

amounts of such noncoking ingredients as anthracite 

fines, petroleum coke, or low-temperature char. 

The nature of the original plant constituents of 

a coal seems .to have an effect in determiuing the 

suitability of a coal for manufacturing coke, and such 

deleterious constituents as ash and sulfur must not be 

present in excessive quantities. 
IOOr-------------------------,--------------------------.--------------------------, 

Thin 

Figure 6. -Summary of percentage distribution of estimated original coal reserves in 10 selected states. 

Most of the reserves of high-rank and highquality coal best suited for the production of coke 

and coal chemicals are found in the East, principally in West Virginia, Pennsylvania, Kentucky, and 

Virginia. In a few areas in the West, principally 

in Colorado, Utah, Oklahoma, Arkansas, Washington, 

and New Mexico, coal is produced that is satisfactory 

for the manufacture of coke when used in blends. 

The most important areas in the West are the Raton 

Mesa region, Colorado-New Mexico; the· Sunnyside 

field, Utah; and the Crested Butte field, Colorado. 

These areas stand out prominently in plans for the 

industrial development of the West. The available 

information about reserves of coking coal in the 

West is summarized in another report (Berryhill 

and Averitt, 1951). 

Because of the almost limitless possibilities 

of blending coals and other hydrocarbons in the 

manufacture of coke, and because of the certainty 

that the acceptable amounts of impurities in coke 

will be allowed to increase and coking properties 

to decrease as the higher rank and higher grade 

coals are depleted, it is impossible to define coking 

coal in precise terms. It may be possible, however, 

to establish certain categories of coal based on 

coking properties, and ash and sulfur contents, conforming to ranges now regarded as acceptable for 

use in making coke, and to report coal reserves 

in these categories, but this has not as yet been 

done. 

As low-volatile bituminous coal is a blending 

component that makes possible the use of vastly 

larger reserves of high-volatile bituminous coal 

for coke production, the reserves of low-volatile 

coal are important in regard to present and future 

supplies of coking coal. The original reserves of 

low-volatile bituminous coal in the United States are 

17 

shown in the accompanying table, as estimated on the 

basis of information available about reserves in the 

several States. 

Relation of original reserves of low-volatile bituminous 

coal to original coal reserves of all ranks in the 

United States. 

Reserves of Percent of total low-volatile coal State (In thousands of coal reserves of 

short tons) all ranks 

West Virginia-------- 10,251,139 8.8 

Pennsylvania--------- 5,672,905 5.8 

Maryland------------- 700,000 40.7 

Oklahoma------------- 2,000,000 3.6 

Arkansas------------- 1,226,000 71.5 

Virginia------------- 300,000 2.5 

Other states--------- 50,000 ---

United States total-- 20,200,044 1.0 

The total estimated reserves of some of the states 

shown in the table will be reduced when new estimates are 

prepared according to modern, restrictive methods, and 

the reserves of low-volatile bituminous coal will be reduced 

accordingly. The ratio of low-volatile bituminous coal reserves to total coal reserves can be expected to remain approximately the same, however, as both the figures cited 

for low-volatile reserves and the figures for total reserves 

in tables 1 and 2 were obtained by the same methods. The 

value of the table lies, not in the figures cited, but in the percentages of total reserves that the figures represent. 

On a tonnage basis the original reserves of lowvolatile bituminous coal represent about 1 percent of the 

total original reserves of coal of all ranks in the United 

States. Mining has been carried on extensively in the 

areas containing low-volatile bituminous coal, however, 

because of the desirable qualities of this rank of coal. As 

a semismokeless fuel with a high heat value, it has many 

uses in addition to the production of coke. In 1947, for 
example, 84, 000, 000 tons of low-volatile bituminous 

coal was mined, of which only about 25 percent was 

used in manufacturing coke (Fieldner, 1950, p. 13-14). 

In many areas of less desirable and less readily 

accessible coal in the United States, the remaining 

reserves are very nearly equal to the original reserves 

because little mining has been done. The areas containing low-volatile bituminous coal on the other hand 

are rapidly being mined out, and the remaining re-' 

serves of this coal are now much less than 1 percent 

of the total coal remaining in the United States of 

which no more than half can be regarded as redoverable. 

With only a limited supply of low-volatile bituminous 

coal available, ·it is apparent that coking operations 

and metallurgical processes soon must be adjusted to 

permit increasing use of lower-rank coal, of which 

larger reserves still remain. 

STRIPPING-COAL RESERVES 

The great increase in strip mining in recent 

years has taken place largely because of the improvement in earth-moving machinery. A modern electric 

shovel that may remove as much as 35 cubic yards at 

a bite is, in fact, a very impressive advance over the 

small "steam" shovel of a few years ago. Because of 

the new efficient strip mining machinery, the amount 

of overburden that can be handled profitably has also 

increased, and many beds previously considered inaccessible for strip mining are now readily accessible. 

For overburden not exceeding about 60 feet, the maximum ratio of thickness of overburden to thickness of 

coal currently considered practicable is about 20 to 1, 

and for overburden exceeding 60 feet somewhat smaller 

ratios are also practicable, although the ratios decrease markedly with increase in the thickness of overburden above the limit of 60 feet, which represents the 

lifting capacity of most modern machinery. 

In 1920, strip mining accounted for only 1. 5 percent 

of the total coal mined, whereas by 1949 strip mining 

accounted for 24. 2 percent of the total. The year 1949 

represents the peak to date for percentage production 

of coal by strip mining. It was due in part to the normal 

growth of the industry and in part to several prolonged 

strikes affecting underground mining production. In 

1950-51, however, the percentage contribution of stripmined coal to total production decreased to 23. 9 and 

22 percent respectively, thereby reversing the trend 

established prior to 1949. The decrease is of particular interest because it occurred during a time when 

total coal production declined, and when strip mining 

had reached a peak of efficiency, and should thus have 

been in a strong competitive position. 

Some of the more spectacular coal mining operations are those where the coal is being recovered by 

stripping methods. The thickest bed now being mined 

by stripping in the United States is at Wyodak, Wyoming, 

where the coal is 90 feet thick. Th~ deepest strip pits 

in the United States are in the, Pennsylvania anthracite 

fields, where an overburden of 120 feet and more is 

being removed. A feature of the mining is this area 

is the fact that the outcrops are now being worked for 

the third time. The first time was by underground 

mining, which recovered only a small percentage of 

the coal near the outcrops. The second time was by 

stripping along the outcrop with small shovels. The 

18 

third time is by stripping the so-called mined-out 

zone just below the older stripped zone with large 

drag-lines and shovels. 

The total stripping coal reserves in the United 

States have not been estimated. That strippable 

reserves are large is suggested by the fact that 

117, 618, 000 tons of coal was mined by stripping 

methods in 1951. Because of physical restrictions, 

however, strippable coal represents only a small part 

of the total reserves, particularly in the eastern states 

where most coal is mined and used. 

The reserves of strippable coal have been calculated for Kansas and Indiana. The proved strippable 

reserves in Kansas, as of 1947, totalled 60, 000, 000 tons, 

based on an assumed weight of 1, 500 tons per acrefoot (Abernathy, 1947). This figure represents 

0. 3 percent of the total estimated coal reserves in 

the State. In Indiana, the strippable coal reserves, 

as of 1950, totalled 3, 524, 170, 000 tons, based on an 

assumed weight of 1, 800 tons per acre-foot (Spencer, 

1953). This tonnage is 9. 4 percent of the total coal 

reserves in the State. 

Montana and North Dakota probably have larger 

reserves of strippable coal than any other states. In 

these two states, about half of the coal produced is 

mined by stripping methods. The U. S. Geological 

Survey has four reports in preparation on selected 

areas favorable for large scale strip mining in 

Montana and North Dakota (Kepferle, in preparation; 

May, in preparation; Culbertson, in preparation; 

Brown, A. , and others, in preparation). 

The use of stripping methods in mining serves 

in several ways to increase the total amount of coal 

that is ultimately recoverable. This is accomplished 

largely by the increase in recovery of coal inherent 

in the mining method, for strip mining recovers an 

average of 80 percent of the total coal in the ground, 

as compared with 50 percent for underground mining. 

Strip mining also adds to the total coal reserves by 

making possible the mining of coal under shallow 

overburden or in badly faulted areas where underground 

mining could not take place. Isolated pockets of coal 

that do not warrant the investment necessary for underground mining can often be recovered economically by 

strip mining. 

In some individual operations, when stripping 

has been extended as far as is justified for reasons 

of economy and safety, additional coal is recovered 

by the use of a. horizontal auger which bores into the 

coal bed at the base of the highwa.ll. The large size coal 

auger has diameters up to 60 inches and penetrates 

a maximum of 200 feet into the bank. This method 

permits a theoretical recovery of 75 percent of the 

coal actually being mined. 

Recently, mining at the outcrop of the coal bed has 

been further extended by the use of a continuous mining 

system in which a machine equipped with four overlappinq 

cutting heads produces a hole approximately 10 feet wide 

and 3 feet high. The full height of the coal bed can be recovered by means of successive cuts. Currently, the 

depth of the hole is limited to 1, 000 feet, the length of the 

cable supplying power. The thickness of the pillar left 

between borings depends upon roof conditions, but, in 

general, recovery of coal by means of this continuous 

mining system is approximately 65 percent. 
PRODUCTION OF COAL IN THE UNITED STATES 

The United States now produces more than onefourth of all the coal mined in the world. The accumulative recorded I-roduction in the United States to 

January 1, 1953, is about.31, 405 million tqns, half of 

which has been produced since 1923. In 1947, the year 

of all-time peak production, the United States produced 

688 million tons. This amount would have filled about 

28 continuous lines of coal cars extending from New 

York to San Francisco. 3 The accompanying map 

(fig. 7) shows the distribution of coal production in 

the United States in 1950. Most conspicuous on the 

map is the preponderance of production from the 

Appalachian Basin, and the fact that more than 

90 percent of the production comes from coal fields 

east of the Mississippi River. 

In the early 1800's production began to increase 

rapidly, and more than doubled during some decades 

in the first half of the century. Production continued 

to double every 10 years or so until about the time of 

World War I. An early peak in coal production was 

reached in 1918 when 678 million tons was mined; 

this amount was not exceeded until 1944, during 

World War II, when 683 million tons was mined. The 

long interval of no expansion in the coal industry came 

during the 1920's, when the use of oil and gas began 

to expand, and during the 1930's, when business was 

depressed. Nevertheless, considerable progress in 

mining methods was made during the period. In 1920, 

for example, less than 1 percent of the coal produced 

by underground methods was mechanically loaded, 

whereas by 1951 nearly 70 percent was mechanically 

loaded. In 1920 strip mining accounted for only 1. 5 per-

~ent of the coal produced, whereas by 1951, strip minmg accounted for 22 percent of the coal produced. 

STATE ESTIMATES 

As somewhat different assumptions and procedures were used to prepare many of the state reserve estimates presented in this report, comparison of the 

reserves in different states is facilitated by a consideration of the methods by which each estimate was 

obtained. Even in the recent appraisals of coal reserves prepared by the U. S. Geological Survey according to the basic outline already discussed, minor differences in procedures were necessary because of 

differences in the occurrence of the coal and in the 

amount of information available. Even greater differences in assumptions and procedures exist between 

estimates prepared by the state geological surveys of 

Illinois, Kansas, Pennsylvania, and West Virginia. 

The following summaries, arranged in alphabetical 

order according to the name of the state, describe and 

evaluate the various methods followed in preparing the 

individual state estimates. Wherever possible, the 

reserve figures for each state are further classified 

according to thickness of coal beds, amount of overburden, and abundance of reliable information, in 

order to give the estimates additional significance and 

usefulness. States for which no recent estimates are 

available, and for which the older estimates of M. R. 

Campbell are used, are included under the heading 

"Other states. 11 

11 This figure is "based on the assumption that one mile of loaded 

coal cars contains 7.:.,:500 tons of coal. 

19 

Arkansas 

The bituminous coal reserves of Arkansas have been 

estimated by Steel (1910) and by Campbell. On the basis 

used by Steel the estimated original reserves would 

total 1, 095,J.68, 000 tons, whereas, the original reserves as estimated by Campbell total 1, 716, 000,000 tons. 

Steel based his estimate on the Hartshorne coal 

bed alone because it contains most of the reserves in 

Arkansas. He assumed the bed to average 3 feet in 

thickness over an area of 310 square miles, and to 

have an average specific gravity of 1. 35, or a weight 

of 1, 840 tons per acre-foot. 

Campbell estimated the reserves in the Hartshorne 

and in other beds as thin as 14 inches over the entire 

coal-bearing area of 1, 600 square miles. He assumed 

the coal to have an average specific gravity of 1. 3,or 

a weight of 1, 770 tons per acre-foot. The Campbell 

estimate is used in tables 1 and 2. The validity of 

both estimate? needs to be checked, however, in the 

light of recent information available on the coal field 

in Arkansas. 

Colorado 

The original reserves of coal in Colorado, as 

provisionally estimated by Spencer and Erwin (1953), 

totaled 100, 408 million tons. This figure, which is 

preliminary to a more detailed study, includes 

713 million tons of anthracite, 90,258 million tons 

of bituminous coal, and 9, 437 million tons of subbituminous coal. 

Of the totallOO, 408 million tons of coal estimated 

to have been originally present in the State, 959 million 

tons has been mined out or lost in mining to January 1, 1952; 

the remaining reserves as of that date therefore total 

99,449 million tons. Assuming 50 percent recoverability for the coal the recoverable reserves in Colorado total 49, 725 million tons. 

The estimate of original reserves, classified by 

counties and fields, was based on published and unpublished reports of the U. S. Geological Survey and on 

records made available by mining companies. 

Of the 25, 400 square miles of coal-bearing land 

believed to be present in the State only 5, 277 square 

miles or 20 percent was included in the estimate. Although the coal probably almost completely underlies 

several large basin areas, such as the Denver basin 

and the Uinta Basin, the data used to compile the estimates were restricted for the most part to areas 

within six miles or less of the coal outcrops. No estimates were made for parts of the State where coal 

is perhaps present but specific information was lacking. 

As more mapping and exploratory drilling is carried 

on in the coal-bearing areas in Colorado, the estimate 

of reserves should be substantially increased. 

No attempt was made in this preliminary estimate 

to classify the reserves according to thickness of overburden, thickness of beds, or other reserve categories. 

In calculating the reserves, the minimum thick- ness of coal considered in the estimate was 14 inches 

for bituminous coal and anthracite and 2-! feet for 

subbituminous coal. 
1:\:) 

0 

···~\ o I 

-

----~-I 

0 

///- t1' CH 

! __ ./ __ --..., 

LJ* 1....., --~ ... 

' 

~ 

EXPLANATION 

2:D Million short tons 

= 100,000 to 1,000,000 tons 

* L7 Less than 100,000 tons 

~Cool field 

""::: 

J ' ~ -, 

0 ~ I 

oi•~ \ D 

0 200 400 600 Miles ,,., __ .•• 

Figure 7. --Distribution of coal production in the United States during 1950. 
The bituminous coal was assumed to weigh 

1, 800 tons per acre-foot; the subbituminous coal was 

assumed to weigh 1, 770 tons per acre-foot; and the 

anthracite was assumed to weigh 2, 000 tons per acrefoot. 

Georgia 

The original coal reserves of Georgia are here 

assumed to be 100 million tons on the basis of work by 

Sullivan (1942, p. 45-51), Johnson (1946), and Butts 

and Gildersleeve (1948, p. 109). This figure has been 

selected as a convenient way to reconcile the estimates 

of 198, 40, and 155 million tons, respectively, as published, or derived from the data published by the three 

workers. Most of the difference between the three estimates is due to differences in the assumptions on which 

they were based, and it can be shown by an analysis of 

the estimates that the selected figure of 100 million tons 

is fair as an approximation of the original reserves in 

all categories in all beds 14 inches or more thick which 

is the basis on which reserves in most other stat~s are 

compared. 

The coal-bearing rocks in Georgia cover about 

170 square miles in parts of Dade, Walker, and 

Chattooga Counties in the northwestern part of the State. 

The geology of this area is described in a report by 

McCallie (1904), which includes much useful information 

about the coal, but does not include estimates of reserves. 

Each of the three recent reports mentioned above describes only the Sand and Lookout Mountains area in 

Dade and Walker Counties, which covers about 120 square 

miles, or about 70 percent of the total coal-bearing area. 

At least 11 coal beds have been identified in the Sand 

and Lookout Mountains area, but mining on a commercial scale has been limited to 5 or 6 beds which in 

general, are considered to contain all of the res~rves. 

The area to the south, which is not considered in 

the three reports, covers about 30 percent of the total 

coal-bearing area in Georgia, but the coal beds are reported to be thinner and less extensive than those in the 

area to the north. 

Sullivan (1942, p. 45-51) who prepared the first 

of the three reports on the Sand and Lookout Mountains 

area, calculated original reserves for 5 coal beds and 

arrived at a total of 197,585,000 tons. He omitted reserves in the Durham (No. 3) bed and the A (No. 1} bed 

which, although of small areal extent, have been computed in other estimates; but he included the Red Ash bed 

which is reported to be generally less than 14 inches ' 

thick and is not included in other estimates. Other 

assumptions used in preparing the Sullivan estimate 

were not specified in the report. 

Johnson (1946~, who prepared the second report 

on the Sand and Lookout Mountains area, estimated 

that the remaining coal reserves as of 1945 totaled 

about 24 million tons, and that the original reserves 

totaled about 40 million tons (personal communication). 

This esttmate includes the reserves in 5 beds with average thicknesses ranging from 1. 3 to 3. 3 feet. 

Butts and Gildersleeve (1948, p. 109), who prepared the third report on the area, considered the reserves in 6 beds with average thicknesses ranging from 

2. 0 to 3. 3 feet. They listed for each bed the average 

21 

thickness, acreage, percentage of area worked out, 

and percentage of the area unworkable. Assuming that 

the coal weighs 1, 800 tons per acre-foot, calculations 

based on their data show that the original workable reserves totaled 154, 978, 560 tons, of which 34, 557, 210 tons 

had been mined out as of the date of their estimate. 

The estimates made by Sullivan and by Butts and 

Gildersleeve are considerably iarger than the estimate 

made by Johnson. A large part of this difference may 

be attributed to different interpretations of the Dade and 

the Rattlesnake beds. Johnson considered Dade and 

Rattlesnake as local names for a single coal bed, the 

No. 9 bed of his report, which in his estimate accounts 

for about 1 percent of the total estimated reserves. 

Sullivan and Butts and Gildersleeve, however, considered them to be two separate beds_, which in their 

estimates account for more than 70 percent of the estimated coal reserves. If only one bed is assumed to be 

present, in the interest of conservatism, the Butts and 

Gildersleeve estimate would be reduced to something 

between 89 to 103 million tons, and the Sullivan figure 

would range from 97 to 156 million tons. 

Although the Johnson figure of 40 million tons is 

based conservatively on careful, detailed work, the 

fact that other later workers arrived at higher figures, 

and the fact that about 30 percent of the coal-bearing 

areas is not covered by recent detailed mapping suggest that a higher figure should be selected for the 

original reserves of the State. The 100 million figure 

selected to serve this purpose is intermediate between 

the published figures, and should be serviceable until 

further detailed work is done. 

Illinois 

As recently estimated by the Illinois Geological 

Survey(Cady, and others, 1953) the remainingreserves of 

Illinois on January 1, 1950, totaled 137, 321, 111, 000 tons. 

In this new and detailed estimate the minimum 

thickness of coal considered was 28 inches, except for 

areas of strippable coal where an average thickness of 

24 inches was used. Coal underlying large towns was 

not included in the estimate; nor was coal underlying 

known oil fields and areas of closely spaced rotary 

drilling, except for an area in Franklin County where 

such drilling was done in close cooperation with active 

mining. Approximately 90 percent of the estimated 

reserves is less than 1, 000 feet below the surface; 

the remainder is between 1, 000 and 1, 200 feet below 

the surface. 

A fourfold classification of reserves was used in 

the Illinois Geological Survey estimate as follows: 

I-A, Proved reserves; I-B, Probable reserves; II-A, 

Strongly indicated reserves; and II-B, Weakly indicated reserves. The Proved and Probable categories 

correspond approximately to the Measured and Indicated categories of the U. S. Geological Survey. 

Class I-A, Proved reserves, includes coal extending no more than one-half mile from a mined-out 

area, diamond drill hole, or an outcrop. 

Class I-B, Probable reserves, includes coal extending no more than two miles from a mined-out area, 

diamond drill hole, outcrop, or churn drill hole known 

to have been drilled for coal. 
Class II-A, Strongly indicated reserves, includes 

coal extending no more than 4 miles from a mined-out 

area; diamond drill hole; outcrop; churn drill coal 

test hole; churn drill hole drilled for oil, gas, or 

water, if sufficiently detailed logs were available; 

and 11Control 11, rotary drill holes that were sampled 

and logged in the field by members of the Illinois 

Geological Survey. 

Class II-B, Weakly indicated reserves, includes 

coal in areas not included in previous categories, 

where geologic information suggested that the coal was 

at least 28 inches thick. All reserves in this category 

were calculated on the assumed minimum thickness 

of 28 inches. 

Where the strict application of the above definitions produced a number of closely spaced areas all 

in the same category, and the coal was known to be 

relatively uniform, the areas were joined. 

In all calculations the coal was assumed to weigh 

1, 800 tons per acre foot. Where data permitted, isopach 

lines were drawn on the coal beds at 28 inches, 42 inches, 

and at succeeding one-foot intervals; and reserves were 

calculated in each of these categories. If the data were 

too widely spaced to permit the use of isopach lines, 

average thicknesses were estimated for each township. 

The results of the Illinois Geological Survey 

study are summarized in the accompanying table, 

which presents the total remaining reserves in Illinois 

as of January 1, 1950, classified by beds and by reserve categories. The report by Cady and others (1953), 

gives the data in greater detail by beds, counties, re · 

serve categories, and thickness categories, and includes maps of the individual coal beds. 

It should be noted that the Illinois estimate, which 

is for remaining reserves as of January 1, 1950, in 

beds more than 28 inches thick, is markedly more 

conservative than estimates for some other states, 

which are for original reserves in beds more than 

14 inches thick. 

Indiana 

As estimated by Spencer (1953) the original coal 

reserves of Indiana totaled 37, 293, 079, 000 tons, all 

of bituminous rank. This figure includes remaining reserves as of January 1, 1951, totaling 35, 805, 776, 000 tons, 

plus an estimate of coal mined and lost in mining to January 1, 1951, totaling 1, 487,303,000 tons. 

The tonnage estimated as mined and lost in mining was 

computed from information on available maps of minedout areas and is a minimum figure. The estimated recoverable reserves, based on an assumed 80 percent 

Estimated remaining coal reserves of Illinois, January 1, 1950 

(In tha.usands of short tons) 

Coal bed 

Trowbridge ------------------------- Friendsville ----------------------- Danville (Sparland) No. 7 ---------- J arne s town ------------------------·--1 

Herrin No.6 (includes Grape Creek)--

Harrisburg (Springfield)No. 5 ------

Summum No. 4 ----------------------- Indiana IV ------------------------- La Salle (Colchester) No. 2 --------

Dekoven ----------------------------

Indiana III ------------------------ Davis-Wiley ------------------------ Stonefort -------------------------- Bald Hill -------------------------- Campbell Hill ----------------------

Murphysboro ------------------------ Rock Island No. l ------------------ Assumption-Litchfield --------------

Willis ----------------------------- Makanda ----------------------------

Coal beds of unknown correlation 

lower than No. 6 -----------------

I - A 

Proved 

8,396 

1,003,028 

42,147 

12,299,737 

4,168,131 

51,592 

11,946 

1,359,365 

92,150 

167,452 

123,448 

4,540 

27,245 

736 

34,064 

111,286 

27,794 

6,892 

1,962 

21,186 

Reserve categories 

I - B 

Probable 

7,873 

24,449 

3,413,502 

191,363 

21,100,547 

9,593,325 

62,359 

58,072 

3,622,676 

845,075 

687,898 

1,061,644 

39,033 

86,016 

65,230 

265,473 

II - A 

Strongly 

indicated 

70,018 

2,924,154 

367,425 

25,143,881 

19,776,703 

67,585 

61,024 

6,216,399 

1,548,149 

965,550 

1,882,935 

5,028 

147,370 

85,904 

1,010,768 

6,375 

Total ------------------------- 19,563,095 41,124,535 60,279,271 

22 

II - B 

Weakly 

indicated 

5,388 

499,698 

4,093,391 

4,971,819 

364,056 

1,229 

124,343 

6,539 

Total 

16,269 

99,855 

7,84o,3Sl 

6o·o,9:J5 

62,637,556 

38,509,978 

181,536 

131,042 

17,486,188 

2,485,374 

1,820,900 

3,432,084 

4,540 

72,535 

736 

391,794 

268,959 

1,304;035 

6,892 

1,962 

27,561 

16,354,211 137,321,110 
recovery for strippable coal and. 50 percent recovery 

for non-strippable coal, totaled 18, 778, 593, 000 tons. 

as of January 1, 1951. In preparing the estimate, 

which is presented by counties and by beds, data were 

compiled from published reports of the U. S. Geological 

Survey and the Indiana Geological Survey, and from 

records made available by other State and Federal 

agencies, coal companies, and oil companies. 

The reserves were classified in three thickness 

categories as follows: 

More than 42 inches. 

28 to 42 inches 

14 to 28 inches 

The estimated reserves are all under less than 

1, 000 feet of overburden. The coal beds under 90 feet 

of ove_rburden or less were considered strippable providing the ratio of overburden thickness to the coal bed 

thickness was no more than 20 to 1. Where the information was adequate and where the ratio of overburden 

to bed thickness was small enough to classify the coal 

as strippable, the reserves were classified into one of 

three overburden categories, as follows: 

0 to 40 feet 

0 to 60 feet 

0 to 90 feet 

The assumed areal extent of each coal bed was 

determined according to standard U. S. Geological 

Survey methods. The classification of coal beds according to relative abundance and reliability of information on which the calculations were based, was also 

made according to U. S. Geological Survey standards. 

The calculations were based on an assumed weight of 

1, 800 tons per acre-foot. 

The table below shows the estimated original 

coal reserves of Indiana, classified according to 

abundance of information, thickness of bed, and amount 

of overburden. 

Kansas 

Bituminous coal.-The estimated remaining reserves 

ofbituminous coal in Kansas as of January 1, 1950, totaled 

20,774,230,000 tons, which include 1,244,900,000 tons of 

proved reserves and 19,529,330,000 tons of potential reserves. This estimate is a revision by Schoewe (1951a 

and personal communication) of an earlier appraisal by 

Abernathy, Jewett, and Schoewe (1947). The new figures 

differ from previously published figures in part because of recent studies by Schoewe, which show that 

15,000,000 tons of coal in Linn County, Kansas, previously classified as potential should be reclassified as 

proved, and in part because of a revision in the assumed 

weight of the coal in the ground. In the 1947 estimate 

the coal was assumed to weigh 1, 500 tons per acrefoot, whereas in the 1951 estimate it was assumed to 

weigh 1, 800 tons per acre-foot. The data used in estimating the reserves were obtained from field investigations, State and Federal publications, mining 

companies, and private individuals. 

In estimating the reserves the minimum thickness 

considered minable by underground methods at various 

depths is shown in the following table: 

Maximum depth to coal 

(In feet) 

100 

150 

200 

600 

1,200 

Minimum thickness of coal 

(In inches) 

16 

18 

22 

32 

36 

A minimum thickness of 10 inches was assumed in 

estimating the rest of the bituminous coal reserves, 

including strippable coal. Strippable coal was defined 

as coal lying a maximum of 60 feet below the surface, 

or coal having an overburden of not more than 35 cubic 

yards per ton. The reserves were classified according 

to the relative abundance of information into two categories, termed proved and potential. Proved reserves 

were defined as reserves lying within a reasonable distance from a known occurrence of coal, based on the 

Estimated original coal reserves of Indiana 

(In thousands of short tons) 

Overburden Thickness Measured Indicated Inferred Total of bed reserves reserves reserves 

Strippa.ble, 90 ft 14 to 28 in. 71,472 111,815 41,033 224,320 or less 28 to 42 in. 308,134 305,690 111,648 725,472 42 in.+ 1,571,675 672,664 330,039 2,574,378 

'l'otal l, 951, 213"1 1,090,169 482,720 3,524,170 

Nonstrippable, more 14 to 28 in. 264,003 767,369 1,084,860 2,116,232 

than 90 ft 28 to 42 in. 429,949 1,599,542 4,877,426 6,906,917 42 in.+ 3,709,641 5,200,388 15,835,731 24,745,760 

Total 4,403,593 7,567,299 21,798,017 33, 76f5,909 

Total------------------------------- 6,354,874 8,657,468 22,280,737 37,293,079 

23 
exiJerience of the coal industry, and on geological observations of the continuity of coal beds in Kansas. In 

general, the category of proved reserves is believed 

to include only beds that can be mined with profit under 

existing conditions. The limits of potential reserves 

were determined by projection from areas of proved 

reserves. 

In computing proved reserves, a measured thickness of the coal bed was considered to prove the presence of coal of the same thickness in an area of 1 square 

mile. Two or more known occurrences of the same 

coal bed in a distance of 4 miles or less along the general line of strike were assumed to prove the bed to be 

continuous between these points. In calculating potential reserves, a measured thickness of coal indicated 

the presence of coal at the same thickness under 

400 square miles. The maximum overburden used in 

outlining areas of proved reserves was l, 200 feet, and 

the maximum overburden for potential reserves was 

3, 000 feet. The areas of both classes of bituminous 

coal reserves were greatly reduced in many places 

because of additional information as to the location of 

poor coal, thin coal, or the absence of coal. 

Lignite. -The lignite beds of Kansas for which 

there is known, reliable information are in general 

30 inches or less in thickness. The minimum thickness 

accepted by the U. S. Geological Survey in estimating 

lignite reserves is 30 inches. Although the beds are 

thin, the reserves were appraised by the Kansas Survey (Schoewe, 1952) because the lignite has been mined 

in the past and is of local interest. The estimated original reserves of lignite total 198, 000, 000 tons, which 

include 55, 000, 000 tons of marginal reserves and 

143, 000, 000 tons of alleged reserves. 

These two classes were applied, rather than the 

proved and potential categories of bituminous coal, 

because the lignite is extremely variable in thickness 

and pertinent information was scarce. Marginal lignite reserves constitute known beds 30 inches or less 

in thickness. Alleged reserves, which are not associated with any mining activity, are comprised of reported 

beds, the presence of which is suggested by broad geologic field relationships; they are generally appraised 

as being more than 3 feet thick. In estimating the marginal reserves, the lignite was assumed to extend for 

a radius of half a mile from isolated points of measured thickness. The minimum average thickness considered was 12 inches. The maximum overburden employed was 1, 000 feet. The lignite was assumed to 

weigh 1, 750 tons per acre -foot. 

This estimate of lignite reserves is not included 

in tables 1 and 2 because the standards used, particularly regarding the thickness of beds are not in accord 

with those employed elsewhere. 

Maryland 

The remaining coal reserves in Mary land as of 

January 1, 1950, are here estimated to total approximately 1. 2 billion tons. This estimate is based in 

part on two reports by Toenges and others (1949, 1952) 

describing the results of recent investigations by the 

U. S. Bureau of Mines; the Maryland Department of 

Geology, Mines, and Water Resources; and the U. S. 

Geological Survey i.n three of the five coal fields in 

Mary lana. 

24 

The first report pertains to the Georges Creek basin 

and the northern part of the Upper Potomac basin, and 

the second to the Castleman basin. In the areas covered by the two reports the estimated remaining reserves as of the period January 1, 1947-'50, total 

858,998,000 tons. The total estimated remaining reserves of the State are derived by extrapolation of this 

figure on the basis of the proportionate distribution of 

reserves as calculated by Campbell in 1928. According 

to the earlier appraisal by Campbell, the proportionate distribution of reserves in the several 

coal basins in Maryland is as follows: Georges 

Creek basin, 50 percent; Upper Potomac basin, 

20 percent; Castleman basin, 15 percent; Upper 

Youghiogheny basin, 5 percent; and Lower Youghiogheny 

basin, 10 percent. On this basis the total reserves in the Georges Creek, Upper Potomac, 

and Castleman basins constitute 85 percent of the 

total original coal reserves in the State. Approximately 16 percent of the reserves in these basins 

is believed to be outside the areas considered in 

the 1949 and 1952 estimates; therefore, the coal 

in the areas reappraised includes 69 percent of 

the total remaining coal reserves in Maryland. 

If Campbell's estimate of the distribution of reserves in Maryland is correct, and it can be 

assumed that 858, 998, 000 tons is 69 percent of 

the total remaining reserves, then the remaining 

reserves as of the period January 1, 1947-'50, total 

1. 2 billion tons. Based as it is upon a broad 

extrapolation of data from several sources, this 

figure is subject to modification as more information becomes available about Maryland coal reserves. It is, however, of the proper order of 

magnitude for comparison with other states where 

reappraisals of reserves have been completed in 

recent years. 

Production of coal in Maryland to January 1, 1950 

totaled 260,000,000 tons. Assuming a 50 percent loss 

in mining, the amount of coal produced and lost in mining in the State during that period totaled 520, 000, 000 tons. 

Adding this figure to that of 1, 200, 000, 000 tons for remaining reserves as of January 1, 1950, provides an 

estimate of 1, 720, 000, 000 tons for the original coal 

reserves of Mary land. 

The coal-bearing rocks in Maryland include 

about 440 square miles and occur in three parallel 

structural troughs that extend northeastward across 

Garrett and Allegany Counties in the western part of 

the State. Within these three troughs five separate 

coal fields, or coal basins, are recognized. The 

easternmost trough is divided by the Potomac and 

Savage Rivers into the Georges Creek basin to the 

north and the Upper Potomac basin to the south. The 

central trough is divided into the Castleman basin to 

the north and the Upper Youghiogheny basin to the 

south. The westernmost trough is known as the Lower 

Youghiogheny basin. 

The following paragraphs summarize briefly the 

recent appraisals of reserves remaining in the Georges 

Creek basin and the northern part of the Upper Potomac 

basin, and in the Castleman basin. 

In 1949, Toenges and others estimated the remaining reserves in the Georges Creek basin and the 

northern half of the Upper Potomac basin, as of 

January 1, 1947, to total 626,729,000 tons. The 

estimate includes reserves in 10 beds, 18 inches thick 
or more lying below the Pittsburgh bed. The Pittsburgh 

bed and the over lying Sewickley bed have been mined ex tensi vely in the past and are now nearly depleted. Because the 

known thick coal beds omitted from the estimate are nearly 

mined out, the published figure represents essentially the 

total remaining reserves in the area covered by the report. 

The reserves are classified according to the relative a bundance and reliability of information into measured, indicated, and inferred reserves, and according to thickness 

into four categories. The coal is of low volatile bituminous rank and is strongly coking. 

In 1952, Toenges and others estimated the remaining 

reserves in the central part of the Castleman basin as of 

January 1, 1950, to total232, 269, 000 tons. The estimate 

includes reserves in six beds, 14 inches thick or more. The 

reserves are classified according to the relative abundance 

and reliability of information into measured, indicated, and 

inferred reserves; and according to thickness into three categories. The coal is of low to medium-volatile bituminous 

rank and in general is strongly coking. 

The estimates for the part of the Maryland coal fields 

contained in the reports discussed above are conservative, 

as may be concluded from observation of the separate bed 

maps accompanying the reports. These maps show the 

areal extent of the coal reserves estimated, the location of 

a comparatively large number of drill holes, and the thickness of the coal at many of the drill-hole locations. Another 

factor responsible for the conservative nature of the estimate is the minimum thickness of 18 inches used in the 

Georges Creek and Upper Potomac basin report, for in the 

Castleman basin report and in most other reserve estimates 

of bituminous coal, the minimum thickness of coal is 

14 inches. The selected provisional figure of 1. 2 billion 

tons for the remaining reserves in Maryland as of January 1, 

1950, thus appears to be reasonable and conservative. 

Michigan 

As estimated by Cohee and others (1950) the original 

coal reserves of Michigan totaled 296, 900, 000 tons. This 

figure includes remaining reserves as of January 1, 1950, 

totaling 219, 900, 000 tons plus an esti rna te for coal mined 

and lost in mining to January 1, 1950, totaling 77,000,000 tons. 

The reserves remaining on January 1, 1950, include 

124,870, 000 tons of measured reserves, 28, 980, 000 tons 

of indicated reserves, and 66, 050, 000 tons of inferred reserves. The estimate of 77, 000, 000 tons for coal mined 

and lost in mining to January 1, 1950, includes the recorded 

production of 46, 239, 607 tons, plus an allowance for coal 

lost in mining estimated to be equal to about 40 percent of 

the coal originally in the ground. To prepare the estimate, 

which is classified to show the distribution of total reserves 

by counties and by townships, data were assembled from 

published and unpublished reports in the files of the Michigan 

Geological Survey Division, and more than 2, 500 logs of 

coal test wells and several hundred sets of drill cuttings from 

exploratory wells for oil and gas were examined. 

As coal in Michigan occurs sporadically in isolated 

beds that vary greatly in thickness and generally pinch out 

in relatively short distances, satisfactory estimates of extent and average thickness were possible only for relatively 

small areas. In preparing the estimate of Michigan coal reserves, therefore, only those areas having adequate testhole information were considered, and no estimate was 

attempted for a large part of the Michigan coal basin where 

coal should be present but where specific information was 

lacking. The part of the coal basin for which the necessary 

information was available was confined to the Saginaw Valley, 

south and southeast of Saginaw Bay, and included 

25 

33 townships in Bay, Tuscola, Midland, Saginaw, Huron, 

Shiawassee, and Genesee Counties. 

The measured coal reserves in Michigan were divided into the following categories according to the thickness 

of the coal beds: 

More than 42 inches 

28 to 42 inches 

14 to 28 inches 

'fhe measured reserves were also divided into the 

following categories according to the thickness of overburden: 

50 to 100 feet 

100 -co 200 feet 

200 to 300 feet 

300 to 400 feet 

No attempt was made to break down the indicated and inferred reserves into thickness and depth categories because of the small amount of information available on these 

reserves. The indicated and inferred reserves are containedinbeds 14inchesormorethick, however, andare 

less than 400 feet below the surface. 

In classifying the reserves according to the relative 

abundance and reliability of the information on which the 

estimate was based, the usual U. S. Geological Survey 

standards were modified slightly to accord with the geologic 

nature of the coal beds in Michigan. Measured reserves 

were defined as reserves blocked out by closely spaced 

drilling, and the outer limit of a block of measured reserves 

was drawn within a few hundred feet of the outermost points 

of positive information. This conservative assumption was 

necessary to define measured reserves in Michigan because 

of the known lack of continuity of the beds. Indicated reserves were defined as reserves for which tonnage estimates 

were based primarily on thickness measurements in isolated drill holes. It was assumed that the thickness of coal 

observed in the drill holes was representative of the area 

covered by a circle having a: radius of one-eighth mile with 

the drill hole as its center. Inferred reserves were defined 

as reserves for which tonnage estimates were based on the 

isolated drill holes that were also used in computing indicated reserves. The general rule was to limit inferred reserves to the area lying outside the one-eighth mile circle 

containing indicated reserves, and inside a circle with a 

radius of one-fourth mile. In some areas, however, where 

-drill holes were more than half a mile but less than 1 mile 

apart, and where the evidence indicated that the coal was 

fairly persistent; some reserves were inferred to be present between the holes. In calculating the reserve figures, 

the coal in Michigan was assumed to weigh 1, 8W tons 

per acre-foot. 

The tabulation on page 26 shows the estimated remaining coal reserves of Michigan as of January 1, 1950, 

classified according to thickness of bed, thickness of 

overburden, and abundance of reliable information. 

Missouri 

The original coal reserves of Missouri as estimated 

by Hinds (1913) totaled 79, 362, 016, 000 tons, all of bituminous raRk. In Hinds 1 report the reserves are classified 

by counties, and, for certain counties, additional tables 

are presented to show reserves by coal beds or by townships. 

The estimate includes all coal beds 14 inches or 

more in thickness based on an assumed weight of 1, 800 tons 
Estimated remaining coal reserves of Michigan, January l, 1950 

(In thousands of short tons) 

Overburden Thickness Measured Indicated Inferred Total of bed reserves reserves reserves 

Bituminous coal 

(14 to 28 in. 1,180 --- --- --- 50 to (28 to 42 in. 1 2,630 --- --- --- 100 feet (42 in.+ --- --- --- --- Total 1 3,810 --- --- ---

(14 to 28 in. 23,800 --- --- --- 100 to (28 to 42 in. 64,100 --- --- --- 200 feet (42 in.+ 10,160 --- --- --- Total 98,060 --- --- ---

(14 to 28 in. 3,920 --- --- --- 200 to (28 to 42 in. 2 14,430 --- --- --- 300 feet (42 in.+ 4,650 --- --- --- Total 2 23,000 --- --- ---

Total ------------------------------ 124,870 3 28,980 3 66,050 219,900 

1 Includes 30 thousand tons with overburden ranging from 22 to 26 feet. 2 Includes 3,010 thousand tons with overburden ranging from 300 to 366 feet. 3 Estimate not classified by thickness of bed or amount of overburden. 

per acre-foot for the coal. No attempt was made to classify 

reserves according to thickness of beds or overburden. 

Hinds further estimated that the recoverable coal reserves of Missouri, assuming ideal market and labor conditions, will not exceed 60 percent of the original reserves, or 47,702, 108,400 tons. 

Montana 

The original coal reserves of Montana totaled 

222, 046, 940, 000 tons, as estimated by Combo and others 

{1949). This estimate ·includes 2, 362, 610, 000 tons of 

bituminous coal, 132, 151, 060, 000 tons of subbituminous 

coal, and 8"7, 533,270,000 tons of lignite. The 

distribution of the coal reserves of various ranks 

in Montana is also shown on a map by Combo and 

others (1950). 

Published and unpublished detailed geologic 

reports in the files of the U. S. Geological Survey, 

publications of the Montana State Bureau of Mines 

and Geology, and similar sources were analyzed 

for data necessary for the calculation of the Montana 

reserve figures, Vv nich are classified by rank, 

counties, thickness of beds, and relative abundance 

and reliability· of the available information. Approximately 10 percent of the total area of coal-bearing 

rocks in Montana was not included in the estimate 

because no information was available on the thickness and extent of the beds. The areas omitted are 

concentrated, in general, in the northeastern, lignitebearing part of the State, where the coal-bearing 

rocks are concealed by glacial drift. The estimated 

reserves of lignite should be increased in the future 

as more detailed work is carried on in these areas. 

The minimum thickness of coal considered in 

the estimate was 14 inches for bituminous coal, 

and 2-! feet for subbituminous coal and lignite. 

For the purpose of classifying the reserves, separate 

26 

estimates were prepared for coal in the following 

thickness ranges: 

Rank Thickness categories 

More than 36 inches 

Bituminous coal---------------- 24 to 36 inches 

Subbituminous coal and 

lignite----------------------

14 to 24 inches 

More than 10 feet 

5 to 10 feet 2t to 5 feet 

The estimate includes reserves to a maximum depth 

of 2, 000 feet below the surface. No attempt was made to 

estimate reserves in intermediate overburden categories, 

but it is believed that approximately 75 percent of the 

total is less than 1, 000 feet below the surface. 

The assumed areal extent of each coal bed was determined according to the standard U. S. Geological Survey 

methods. Coal in the narrow weathered zone at the outcrop 

was included in the assumed areas of coal occurrence, as 

was coal under roads, railroads, and the like. All known 

areas of burned coal were excluded. 

Two classes of coal, based on the quantity of reliable 

information available for making reserve estimates, were 

established: (1) Measured and indicated reserves, (2) inferred reserves. Measured and indicated reserves include 

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 was less .than 2 miles from the outcrop and more than 

50 percent was less than 1 mile from the outcrop. Inferred 

reserves include, in general, coal lying more than 

2 miles from the outcrop. 

Based on 20 specific gravity determinations of coal 

from various parts of Montana, a specific gravity of 1. 3, 

or a weight of 1, 770 tons per acre-foot, was selected as 

being representative of lignite and subbituminous coal. 
A specific gravity of 1. 32, ora weight of 1, 800 tons per 

acre-foot, was selected as being representative of all the 

bituminous coal except that in the Red Lodge field, Carbon 

County, which was assigned a specific gravity of 1. 39, 

or a weight of 1, 890 tons per acre-foot. 

The accompanying table shows the estimated 

original coal reserves of Montana classified according 

to rank, thickness of bed, and relative abundance of 

reliable information. 

Estimated original coal reserves of Montana 

(In thousands of short tons) 

Measured and 

Thickness Inferred indicated Unclassified Overburden of bed reserves reserves Total reserves 

l3ituminous coal 

(14 to 24 in. 278,780 167,080 --- 445,860 0 to (24 to 36 in. 347,690 143,740 --- 491,430 2,000 feet (36 in.+ 1,036,330 388,990 --- 1,425,320 

Total 1,662,eoo 699,()10 --- 2,362,610 

Subbituminous coal 

(2~ to 5 ft 5,392,110 2,326,150 --- 7,718,260 

0 to (5 to 10 ft 15,485,620 9,245,940 --- 24,731,560 2,000 feet (10 ft + 26,370,190 15,974,920 --- 42,345,110 

(Unclassified --- --- 57,356,130 57,356,130 

Total 47,247,920 27,547,010 57,356,130 132,151,060 

Lignite 

(2~ to 5 ft 4,876,170 10,177,750 --- 15,053,920 0 to 

2,000 (5 to 10 ft 6,613,070 13,135,880 --- 19,748,950 feet (10 ft + 2,566,030 435,000 --- 3,001,030 

(Unclassified --- --- 49,729,370 49,729,370 

Total 14,055,270 23,741:5,630 49,729,370 87,533,270 

T otal, 

all ranks --------------------------- 62,965,990 51,995,450 107,085,500 222,046,940 

New Mexico 

The original coal reserves of New Mexico totq.led 

61, 754, 600,000 tons, a.s estimated by Read and others 

(1950). This figure includes 50, 801, 200, 000 tons of 

subbituminous coal, 10,947, 700,000 tons of bituminous coal, and 5, 700, 000 tons of anthracite. The 

estimate, which is classified to show reserves by 

counties and coal fields, and other categories as outlined below, was based on published and unpublished 

geologic and mining data concerning the coal fields. 

Drilling data were used where available, but exploratory drilling for coal has been carried on only in a 

few areas in the State. 

The minimum thickness of coal considered in 

preparing the New Mexico estimate was 2! feet for 

subbituminous coal and 14 inches for bituminous coal 

and anthracite. Reserve figures for the different ranks 

of coal were classified by thickness of bed as follows: 

Rank 

Subbituminous coal-------------

Bituminous coal and 

anthracite-------------------

Thickness categories 

2~ to 5 feet 

5 to 10 feet 

More than 10 feet 

14 to 28 inches 

28 to 42 inches 

More than 42 inches 

27 

In areas where information about the thickness 

of coal beds was reasonably adequate because of 

drilling and mining development, isopach lines drawn 

on the coal beds were used to determine variations in 

thickness, and to establish boundaries between coal 

in the several thickness categories. In many districts, 

however, where the data were restricted to outcrop 

measureii1ents, it was possible to determine only 

approximate thicknesses at critical points by interpolation. 

Coal lying more than 3, 000 feet below the surface was not included in the estimate. For coal less 

than 3, 000 feet in depth the following categories of 

reserves were established according to thickness of 

overburden: 

0 to 1,000 feet 

1,000 to 2,000 feet 

2,000 to 3,000 feet 

The coal reserves of New Mexico were further 

classified according to the relative abundance andreliability of the information on which calculations were 

based. The categories of measured, indicated, and 

inferred reserves were established according to the 

U. S. Geological Survey standards already described. 

One further category was added, however, to provide 

for· reserves which, because of the geologic nature of 
0 

the coal beds and the topography and structure of the 

larger coal-bearing areas, would not fit into any of 

the three categories generally used. In New Mexico 

the coal beds commonly occur in zones as a series of 

lenticular deposits interbedded with other sedimentary 

rocks. Although single coal beds in New Mexico are 

limited in extent, the coal-bearing zones are very persistent and may be regional in occurrence. In 

consequence, the usual analysis of reserves by beds 

would not indicate the total reserves of the interior 

parts of the San Juan Basin or the Raton Mesa field. 

The coal zones were therefore subjected to further 

examination a.s zones instead of individual beds 

and the additional reserves thus derived were included in a fourth category termed "inferred 

Overburden 

to 

1,000 reet 

by zone." 

Estimated original coal reserves or New Mexico 

(In thousands or short tons) 

Thickness Measured Indicated Inrerred 

or bed reserves reserves reserves 

Bituminous coal 

(14 in.+ --- --- --- (14 to 28 in. 72,800 359,100 334,300 

(28 to 42 in. 151,900 334,200 27,100 

(42 in.+ 429,500 611,600 360,100 

Total 654,200 1,304,900 721,500 

(14 in.+ --- --- ---

Reserves 

inrerred Total 

by zones 

2,377,900 2,377,900 --- 766,200 

--- 513,200 

--- 1.401. 200 

2,377,900 5,058,500 

1,763,600 1,763,600 1,000 to (14 to 28 in. 400 7,100 694,300 --- 701,800 2,000 reet (28 to 42 in. --- 39,400 355,400 --- 394,800 (42 in.+ --- 69,400 715,300 --- 784,700 

Total 4oo 115,900 1,765,000 1,763,600 3,644,900 

(14 in.+ --- --- --- 1,838,900 1,838,900 2,000 to (14 to 28 in. --- 2,600 25,300 --- 27,900 3,000 reet (28 to 42 in. --- 600 --- --- 600 

(42 in.+ --- --- 376,900 --- 376,900 

Total --- 3,200 402,200 l ,--s-:W, 900 2,244,300 

Total ---------------------- 654,600 1,424,000 2,888,700 5,980,400 10,947,700 

Subbituminous coal 

(2! rt + --- --- --- 16,363,500 16,363,500 0 to (2! to 5 rt 446,800 1,021,300 1,227,000 --- 2,695,100 1,000 reet (5 to 10 ft 228,100 348,400 997,600 --- 1,574,100 

(lo rt + 151,600 160,900 --- --- ?12.1:)00 

Total 826,500 1,530,600 2,224,600 16,363,500 20,945,200 

(21- rt + --- --·- --- 13,154,700 13,154,700 1,000 to (2I to 5 rt --- 60,900 165,300 --- 226,200 2,000 reet (5 to 10 rt --- 39,100 743,800 --- 782,900 

(lo rt + --- 121,300 537,800 --- 659.100 

Total - --- 221,300 1,446,900 13,154,700 14,822,900 

(21- rt + --- --- --- 13,288,000 13,288,000 2,000 to (2I to 5 rt --- 3,600 502,000 --- 505,600 3,000 reet (5 to 10 rt --- 12,100 448,600 --- 460,700 

(lo rt + --- --- 778,800 --- 778,800 

Total --- 15,700 l,729,l.f.OO l3,2t5t5,000 15,033,100 

Total ---------------------- 826,500 1,767,600 5,400,900 42,806,200 50,801,200 

Anthracite 

(14 in.+ --- --- --- --- --- 0 to (14 to 28 in. 900 2,500 --- --- 3,400 1,000 feet (C:3 to 42 in. 1,400 300 --- 1,700 

(42 in.+ 1- 500 100 --- --- 600 

Total 2,800 2,900 --- --- 5,700 

Total ---------------------- 2,800 2,900 --- --- 5,700 

Total, 

all ranks----------------- 1,483,900 3,194,500 8,289,600 48,786,600 61,754,600 
The methods used for coal-zone calculations 

were similar to those used for coal beds, and the same 

minimum thicknesses for coal of different ranks and 

the same ranges in overl:;mrden thickness were established. 

In calculating the reserves of New Mexico, the 

bituminous coal was assumed to weigh 1, 800 tons per 

acre-foot; the subbituminous coal was assumed to 

weigh 1, 770 tons per acre-foot; and the anthracite was 

assumed to weigh 2, 000 tons per acre-foot. 

The estimated original reserves of New Mexico, 

classified according to rank of coal, thickness of bed, 

amount of overburden, and abundance of reliable information, are listed in the tabulation on page 28. 

North Carolina 

All coal of commercial quality in North Carolina 

is contained in the Deep River field in Chatham, Lee, 

and Moore Counties. The original reserves of this 

field, as estimated by Reinemund (in preparation) 

totaled 111, 958, 000 tons. This figure is a revision, 

based on additional data from mining and drilling, of an 

earlier estimate also prepared by Reinemund (1949). 

The reserve estimate includes only coal in the main 

bench of the Cumnock coal bed and in the Gulf coal bed; 

it does not include coal in the lower benches of the 

Cumnock bed, which, in general, are too high in ash, 

too thin, and too far below the main bed for profitable 

mining. In addition to bituminous coal, the estimate 

includes small amounts of semianthracite and anthracite where the coal has been altered locally by igneous 

intrusions. 

The reserves were divided into three classes 

according to the thickness of the coal, and separate 

estimates were prepared for reserves in beds 14 to 

28 inches thick, beds 28 to 36 inches thick, and beds 

more than 36 inches thick. 

The reserves were alsv classified on the basis 

of overburden, and separate estimates were made for 

coal less than 2, 000 feet in depth and for coal lying 

between 2, 000 and 3, 000 feet in depth. No coal more 

than 3, 000 feet below the surface was included 

in the estimate. 

A further classification of the reserve figures 

was made according to the relative abundance of reliable information regarding the continuity and thickness of the coal beds. Reserves were classed as 

measured where the tonnages were computed from 

thicknesses shown in closely spaced drill holes, mine 

workings, and outcrops; as indicated where the tonnages were computed partly from specific measurements and partly from projections of visible data; 

and as inferred where computations were based entirely on geologic evidence without benefit of actual 

measurements. 

In calculating the reserves of the Deep River 

field, a specific gravity of 1. 32, or a weight of 

1, 800 tons per acre-foot, was used for all coal except that metamorphosed by contact with the intrusive 

igneous rocks. A specific gravity of 1. 47, or a weight 

of 2, 000 tons per acre-foot, was assumed for this 

metamorphosed coal. 

The accompanying table (see below) shows the 

estimated original reserves of coal in the Deep River 

field, North Carolina, classified acGording to thickness of bed, amount of overburden, and relative abundance of reliable information. 

North Dakota 

The original lignite reserves of North Dakota as 

estimated by Brant (1953) totaled 350,909,820,000 tons, 

of which 9, 521, 400,000 tons is classed as measured; 

50,120,390,000 tons as indicated; and 291,268,030,000 tons 

as inferred. Approximately 70 percent of the 

total reserves is less than 500 feet below the surface; 

28 percent is 500-1, 000 feet below the surface; and 

2 percent is 1, 000-1, 200 feet below the surface. 

Data used in preparing the estimate were obtained from North Dakota Geological Survey reports, 

mining companies, private individuals, and U. S. Geological Survey reports. The information available 

was limited almost entirely to outcrops of the beds, 

Estimated original coal reserves in the Deep River field, North Carolina 

(In thousands of short tons) 

Overburden 

0 to 

2,000 feet 

Thickness 

of bed 

(14 to 28 in. 

(28 to 36 in. 

(36 in.+ 

Total 

(14 to 28 in. 

2,000 to (28 to 36 in. 

3,000 .feet (36 in.+ 

Total 

Total ---------------------------

1 Includes small amounts of anthracite and semianthracite. 

Measured 

reserves 

Bituminous coal 1 

7,705 

9,037 

20,934 

37,676 

---

8os 

1,183 

1,988 

39,664 

29 

Indicated 

reserves 

24,992 

3,863 

6,786 

35,641 

2,055 

4,923 

7,302 

14,280 

49,921 

Inferred 

reserves 

22,373 

---

---

22,373 

---

---

---

---

22,373 

Total 

55,070 

12,900 

27,720 

95,690 

2,055 

5,728 

8,485 

16,268 

111,958 
but was supplemented by a few drill logs. In many 

areas that were not mapped information was available 

only for the thickest or best known bed. Of the entire 

area considered to be underlain by lignite beds more 

than 2. 5 feet thick, about 1. 7 percent was omitted because no data were available. A substantial increase 

in the estimate for North Dakota should be possible 

when additional mapping and exploration have been 

carried out. · 

The North Dakota reserves were estimated according to the standard procedures of the U. S. Geological Survey as previously defined, and the results 

are tabulated in the Brant report by individual beds 

and townships, in categories according to thickness 

and relative abundance of reliable information available for maki_ng the estimate. A summary of this information is presented in the accompanying table 

(see below). 

Ohio 

According to combined estimates of Clark (1917) 

and Flint (1951), the original coal reserves of Ohio 

totaled 86,583,559,032 tons, all of bituminous rank. 

In 1917, Clark estimated the original reserves of Ohio 

to be 87,638,000,000 tons, of which 2, 141,000, OOOtons 

was estimated to be in Perry County. On the basis of 

new geologic work in 1951, Flint recalculated the reserves of Perry County and estimated the reserves to 

be only 1, 086, 559,032 tons. This new figure has been 

added to Clark's estimate for the remainder of the State 

to give the present total reserve estimate. 

Clark based his estimate, which includes a table 

showing reserves by counties and by coal beds, upon 

data assembled for the most part from reports of the 

Geological Survey of Ohio. All coal in beds 14 inches 

or more thick to a depth of 3, 000 feet below the surface 

was included in the estimate. Average thicknesses for 

each bed by counties were obtained. 

The areal extent of the coal underground was determined by various methods depending upon the amount 

of information available to Clark on each coal bed. 

Higher beds, whose outcrops encircle upland areas, 

were assumed to underlie the area enclosed by the outcrop. Except where positive evidence indicated the absence of coal, each of the lower beds was assumed to 

extend below drainage toward the center of the 

coal basin at right angles to the strike for a 

distance equal to the distance that the bed was 

known to extend above drainage. Where the coal bed 

was. believed to be persistent along its outcrop and 

reasonably constant in thickness, it was assumed to 

have the same average thickness below drainage as 

observed above drainage. 

Several of the coal beds in Ohio were not shown 

on the maps available to Clark. The probable area of 

these beds had to be determined from maps showing 

the outcrop of the base of the coal measures, the outcrops of the more important coal beds, and the locations of coal sections; from the records of deep 

borings; and from references in the texts of the State 

reports. In the calculation of the reserves a weight 

of 1, 800 tons per acre-foot was assumed for the coal. 

In the more recent work in Perry County, Flint 

also used 14 inches as the minimum thickness of coal 

included in his estimate. Of the seven coal beds that 

Clark recognized in Perry County, however, four beds 

were excluded by Flint, because detailed mapping 

:;howed that in this county these beds generally are less 

than a foot thick or are completely missing. In calculating the reserves, Flint also assumed the coal to have 

a weight of 1, 800 tons per acre-foot. 

According to an estimate by Ray (1929, p. 330), 

approximately one-sixth of the total original reserves 

of coal in Ohio, or 14, 399,296, 000 tons, can be classified as reserves of thick, reasonably accessible coal. 

For his estimate Ray included only coal 2. 7 feet or 

more thick in 10 specified beds, and he used an assumed 

specific gravity of 1. 1, or a weight of 1, 500 tons per 

acre-foot, for the coal. This weight is very low for 

bituminous coal in the ground, however, and a more 

accurate, though conservative, figure can be obtained 

by recalculation of Ray's estimate using a specific 

gravity of 1. 32, or a weight of 1, 800 tons per acrefoot. The estimated original reserves of thick coal 

in Ohio would thereby be increased 20 percent, to a 

total of 17,279, 155,800 tons. 

A detailed report on reserves in the Meigs Creek 

(No. 9) coal bed in Ohio by Smith and others ( 1952) 

was published early in 1953 by the Ohio Division of 

Geological Survey. According to this report, the 

original reserves in the Meigs Creek bed in Ohio 

totaled 4, 020, 762, 000 tons, as compared to the earlier 

Clark estimate of 4, 071, 000, 000 tons. The new detailed estimate, which presents the reserve data in a 

number of carefully defined categories for each county, 

is so nearly the same as the earlier, generalized estimate that no change in the over-all reserves of Ohio 

Estimated original reserves or lignite in North Dakota 1 

(In thousands or short tons) 

Thickness or bed Measured Indicated Inrerred reserves reserves reser')ffis Total 

2-! to 5 reet ------------------------------- 3,094,560 20,094,980 224,180,360 247,369,900 5 to 10 reet 

10 ------------------------------- 3,963,720 18,627,180 36,937,700 59,528,600 reet + ------------------------------------ 2,4.63, 120 11,398,230 30,149,970 44,011,320 

Total ---------------------------------- 9,521,400 50,120,390 291,268,030 350.909 820 1 All beds are less than 1,200 ft. below the surface. 

30 
is required. Nevertheless, the new estimate represents ail important step toward full and complete 

knowledge of reserves in Ohio. 

Pennsylvania 

Bituminous coal. -The original bituminous coal 

reserves of Pennsylvania, as estimated by Reese and 

Sisler (1928), totaled 75, 093,459, 000 tons. This figure was determined by plotting on county base maps 

all the information about the area and thickness of the 

coal beds in the State that could be obtained from the 

reports of the U. S. Geological Survey and the Pennsylvania Topographic and Geologic Survey, and from 

drill records, mine maps, ar1d personal interviews 

with mine operators and others familiar with the coal 

fields of Pennsylvania. 

All coal beds having a minimum thickness of 

18 inches were included in the Reese and Sisler estimate. An assumed specific gravity of 1. 24, or a 

weight of 1, 688 tons per acre-foot, was used in calculating the coal reserves of all counties in Pennsylvania 

except Clarion and Jefferson Counties. A specific 

gravity of 1. 34, or a weight of 1, 820 tons per acrefoot, was used in computing the coal reserves of these 

two counties. The specific gravity of 1. 34 not only 

represents the average weight of the coal in two counties 

in Pennsylvania as determined by a large number of 

tests, but it also closely approximates the specific 

gravity of samples of typical bituminous coal in the 

ground. The assumed specific gravity of 1. 24 used 

in calculating the coal reserves of most of the counties 

is low for typical bituminous coal, and therefore, yields 

a conservative figure for the coal reserves of Pennsylvania. Had a specific gravity of 1. 34 been used in 

the calculations for all counties, the estimated bituminous coal reserves of Pennsylvania would have been 

increased by 6 percent to a totalof80, 545, 165, OOOtons. 

Several additional estimates of the coal reserves 

of small areas in Pennsylvania have been calculated 

and can be used as a partial check on the Reese and 

Sisler estimate for the entire State. These estimates 

are discussed in the following paragraphs: 

The coal reserves of the adjoining Punxsutawney 

and Curwensville quadrangles, were estimated by 

G. H. Ashley (1926 and 1940). As Reese and Sisler 

reported reserves by counties and Ashley reported by 

quadrangles, Ashley's estimate for the two quadrangles 

cannot be compared directly with the estimate by Reese 

and Sisler. It is possible, however, to compare the 

two estimates of coal reserves for those townships 

which lie entirely within the Punxsutawney and Curwensville quadrangles. For the 14 townships thus 

situated, Reese and Sisler estimated that the original 

coal reserves totaled 2, 347,600,000 tons, whereas 

AshLey estimated that the original coal reserves totaleq 2, 765,375, 000 tons. Ashley's estimate, therefore, represents an increase of nearly 18 percent over 

.the estimate of Re.ese and Sisler. 

In calculating the reserves of the Curwensville 

quadrangle, Ashley included only coal having an average net thickness of at least 18 inches. In calculating 

the reserves of the Punxsutawney quadrangle, he included only coal having an average net thickness of at 

least 1 foot. Ashley defined the net thickness of the coal 

31 

bed as "the thickness left after rejecting any minor 

benches separated from the main bench by a parting 

of greater thickness than the coal bench. In the case 

of a parting thinner than the coal bench; only the difference in thickness between the minor bench and the parting was added to the thickness of the major bench. 11 

For both quadrangles, Ashley assumed the coal to weigh 

1, 800 tons per acre-foot. 

The coal reserves of the Smicksburg quadrangle 

were estimated by M. N. Shaffner (1946), but again a 

comparison with the Reese and Sisler estimate can be 

made only for the townships lying completely within the 

quadrangle. For six townships, therefore, Shaffner 

estimated that the original coal reserves totaled 

525, 771, 000 tons, and Reese and Sisler estimated that 

the original reserves totaled 931,300, 000 tons. Shaffner's 

estimate is only 56 percent of that made by Reese and 

Sisler. 

Much of the difference between the two estimates 

is probably accounted for, however, by the fact that 

Shaffner determined the thickness of the coal beds used 

in his calculations by the modulus of irregularity. As 

already discussed, this formula results in a figure for 

the thickness of the coal that is less than the average 

thickness, and an estimate based on the use of the 

formula tends to be extremely conservative. This is 

the only known published use of the modulus of irregularity in recent calculations of coal reserves. 

Shaffner assumed a specific gravity of 1. 35, or 

a weight of 1, 840 tons per acre-foot, for the coal in 

the Smicksburg quadrangle. 

F. T. Moyer estimated that the original coal reservestof Fayette County, Pa;, totaled 7, 570,000,000 

tons (Hickok and Moyer, 1940). For the same area 

Reese and Sisler estimated that the original coal reserves totaled 5, 230, 000,000 tons. Moyer's estimate 

represents an increase of 45 percent over the estimate 

of Reese and Sisler. 

The townships in Fayette County were divided by 

Moyer into areas in which the coal showed the same 

characteristics and for which an average section could 

be determined. The area underlain by coal was obtained by planimeter measurements. Minable thicknesses of the average sections were used in all calculations. The minable thickness of a coal bed, as defined by Moyer, is the thickness of the coal remaining 

'after subtracting partings, bone, and bony coal from 

the total thickness of the bed. Thin benches separated 

by a thick parting from the principal bench of a coal 

bed were also excluded in considering minable thickness. No coal having an average minable thickness of 

less than 26 inches was included in the estimate. Moyer 

assumed a specific gravity of 1. 37, or a weight of 

1, 860 tons per acre-foot, for the coal in Fayette County. 

The remaining measured and indicated reserves 

in six counties in the bituminous coal field of Pennsylvania have been estimated recently by Dowd and 

others (1950-52), as part of a program of the U. S. 

Bureau of Mines to investigate known minable reserves of coking coal. The reserves as estimated by 

Dowd and his associates are considerably less than 

those estimated in 1922 by Reese and Si.sler. The 

apparent decrease in estimated reserves is due, for 

the most part, to the fact that the Dowd estimate 
includes only measured and indicated reserves in a 

relatively small area, whereas Reese and Sisler include all classes of reserves in a relatively larger 

area. Dowd considered all beds 14 inches or more 

thick, and used a 3pecific g·ravity of 1. 32, or 1, 800 tons 

per acre-foot. 

The accompanying table (see below) compares 

the two estirr.ates for six counties according to acreage 

and tonnage. 

In the strictest sense none of the reserve estimates just discussed can be compared with the Reese 

and Sisler estimate because of the different standards 

applied, particularly for minimum thickness of coal 

beds and weight of coal. For practical purposes, however, the several recent estimates serve to show the 

conservativeness of the older Reese and Sisler estimate. 

Ashley (1944) recognized the conservative nature 

of the Reese and Sisler estimate and, on the basis of 

the other estimates just described, increased the Reese 

and Sisler figures of original coal reserves 10 percent 

for every county in Pennsylvania except Fayette County 

for which he used the new estimate by Moyer. ' 

As previously mentioned, the low estimate by 

Reese and Sisler is partly the result of the use of a 

lower-than-average specific gravity for the coal in 

Pennsylvania. Recalculation of the estimate using a 

somewhat higher specific gravity for the coal, however, 

still results in a smaller figure for the coal reserves 

of Pennsylvania than is indicated by other estimates 

that include all c~asses of reserves. Considering the 

conservative nature of the Reese and Sisler estimate 

and the fact that no new complete estimate for the cdal 

reserves of Pennsylvania is available, the continued 

use of their estimate without revision in the present 

tables seems justified at this time. 

Anthracite. -The original reserves of anthracite 

in Pennsylvania totaled 22,805, 000, 000 short tons, 

according to the most recent estimate, which was made 

by Ashley (1945). This estimate was based directly 

upon a previous one by Ashmead (1926), with the exception of the reserve figures for two counties, Dauphin 

and Lebanon, which Ashley decreased on the basis of 

later mining reports. 

Ashmead based his reserve estimate on careful 

measurements of coal bed areas as shown on mine 

maps, but he listed no standards for the thickness or 

weight of the coal included. Presumably, therefore, 

in computing the anthracite reserves of Pennsylvania, 

Ashmead, and subsequently Ashley, used the same 

limits of thickness and the same figures for specific 

gravity that were adopted by Smith (1893) who made 

the first careful estimate of the anthracite reserves, 

see also Lesley and others (1895). 

The minimum thickness of coal included in Smith's 

estimate was 2. 5 feet for the Northern anthracite field 

and 2 feet for the other fields. 

In calculating anthracite reserves, Smith used 

different values, as determined by numerous tests, for 

the specific gravity of the coal in different parts of the 

anthracite fields. The coal in the Eastern Middle field, 

Western Middle field, and part of the Southern field was 

assigned a specific gravity of 1. 61, or a weight of 2, 190 ton:: 

per acre-foot. The remainder of the coal in the 

Southern field was assigned a specific gravity of 1. 5, 

or a weight of 2, 040 tons per acre-foot, and the coal in 

the Northern field, was assigned a specific gravity of 1. 55, 

or a weight of 2, 110 tons per acre-fooL Smith estimated that the original reserves of anthracite in Pennsylvania totaled 21, 848, 800, 000 short tons. 

Recent detailed mapping by the U. S. Geological 

Survey in parts of the Western Middle anthracite field 

has revealed a number of faulted and sheared areas 

that are not shown on earlier maps. If such structures 

prove to be numerous throughout the anthracite region, 

future estimates of anthracite reserves may be somewhat reduced (Rothrock, 1950, p. 195). Smith's older 

estimate of 21,848,800, 000 short tons for original reserves may therefore prove to be more accurate than 

the more recent Ashley estimate of 22,805,000, 000 ton~:' 

which has been accepted for use in this report. 

Comparison of coal reserve estimates of Reese and Sisler, and Dowd and others for individual 

counties in Pennsylvania 

Reese and Sisler Dowd and others 

County 1922 1 1950-522 

Acres Tons Acres Tons 

(thousands) (millions) (thousands) (millions 

Armstrong-------------------------------------------- 669 3,643 425 1,550 

Cambria---------------------------------------------- 1,030 4,916 725 2,406 

Fayette---------------------------------------------- 638 4,330 314 943 

Indiana---------------------------------------------- 1,142 6,040 754 2,544 

Jefferson-------------------------------------------- 742 3,056 165 710 Westmoreland----~------------------------------------ 905 5,163 290 922 

Total------------------------------------------- 5,126 27,148 2,673 9,075 

1 

All cla~ses or'remaining re,serv~s, 1922, beds 18 inches or more thick, assuming a weight of 1,688 tons per acre-foot in all counties except Jefferson County, for which the assumed weight IS 1,820 tons per acre-foot. 2 Measured and indicated remaining reserves, 1948-50, beds 14 inches or more thick, assuming a weight of 1,800 tons per acre-foot. 

32 
South Dakota 

The original coal reserves of South Dakota, as estimated by D. M. Brown (1952), totaled 2, 032,910, OOOtons 

of lignite and 10, 900 tons of bituminous coal. The estimate is based on published and unpublished reports 

of the U. S. Geological Survey and the South Dakota 

Geological Survey, and on information provided by 

operating companies and private individuals. The estimated lignite reserves are tabulated in the Brown report by counties and townships and by a number of 

reserve cat~qorie;:;, but the small quantity of bituminous 

coal is described only in the text. 

·In estimating the reserves, the assumed areal 

extent of each coal bed was determined according to 

the standard U. S. Geological Survey procedures. The 

minimum thickness of coal considered was 14 inches 

for bituminous coal and 2-! feet for lignite. The calculation of the lignite reserves was based on three 

thickness categories, as· follows: 

More than 10 feet 

5 to 10 feet 

2~ to 5 feet 

The lignite reserves were further divided into the measured, indicated, and inferred categories, according to 

the relative abundance and reliability of information. 

All reserves were grouped into one overburden category, less than 1, 000 feet. The lignite was assumed 

to have a weight of 1, 750 tons per acre-foot. 

The accompanying table (see below) shows the 

estimated original reserves of lignite of South Dakota 

classified by thickness of bed and relative abundance 

of reliable information. 

Virginia 

. As estimated by Brown and_ others (1952), the origmal coal reserves of Virginia totaled 12,051,270,000 tons, 

of which 932,000,000 tons had been mined and lost in 

mining to January 1, 1951, and 11,119,270,000 tons remained in the ground. Of the total amount cif coal included in the estimate, 97 percent is concentrated in 

the southwest Virginia field, where the coal is of bituminous rank, and 3 percent is in the Valley fields, 

where the coal is semianthracite. No estimates were 

prepared for tlie coals of Triassic age in the Richmond 

and Farmville basins, because the information available was insufficient for the purpose. 

The tabulation listed on page 34 shows the 

distribution of the total remaining reserves of bituminous coal and the original reserves of semianthracite 

in various categories classified according to rank, overburden, thickness of beds, and relative abundance and 

reliability of information. Noteworthy is the fact that 

most of the reserves included in the estimate are less 

than 1, 000 feet below the surface. 

The appraisal of the coal reserves of Virginia 

was prepared by the U. S. Geological Survey in cooperation with the Virginia Geological Survey. Information was obtained from mining companies, private 

individuals, and publications of the two cooperating organizations. In preparing the appraisal, the reserves were 

classified into three categories of thickness as follows: 

More than 42 inches 

28 to 42 inches 

14 to 28 inches 

The reserves were further classified according 

to the relative abundance and reliability of information 

into measured, indicated, and inferred reserves, according to the standard U. S. Geological Survey methods. 

In making calculations the bituminous coal was assumed 

to weigh 1, 800 tons per acre-foot, and the semianthracite 

to weigh 2, 000 tons per acre-foot. 

West Virginia 

The original coal reserves of West Virginia. 

totaled 116, 618, 446, 894 tons, according to an estimate 

by Headlee and Nolting (1940). This figure represents 

the sum of the original coal reserves in each of 44 

coal-bearing counties as estimated in numerous county 

reports published by the West Virginia Geological 

Survey. The Headlee-Nolting summary report includes 

tables showing the distribution of reserves by minable 

coal beds as well as by counties. 

The estimate includes reserves in a few beds 

averaging 1 foot in thickness, but the amount of such 

coal is small. Price and others (1938) state that approximately 75, 500, 000, 000 tons of coal in West Virginia is contained in beds that average 3 feet or more 

in thickness. The remainder of the original reserves 

o'r approximately 41, 000,000, 000 tons, is contained ' 

in the thinner beds. 

In computing the reserves of West Virginia., the 

coal was assumed to have a specific gravity of 1. 28, 

Estimated original reserves of lignite of South Dakota 

(In thousands of short tons) 

Thickness of bed 

Measured Indicated Inferred Total reserves reserves reserves 

2~ to 5 feet-------------------------------------- 104,420 992,480 177,290 1,274,190 

5 to 10 feet-------------------------------------- 33,680 673,490 6o 707,230 

10 feet +------------------------------------------ --- 51,490 --- 51,490 

Total ---------------~------------------------ 138,100 1,717,460 177,350 2,032,910 

33 
Estimated remaining coal reserves of Virg~pia, January l, 1951 

(In thousands of short tons) 

Overburden Thickness 

of bed 

Measured 

reserves Indica teo reserves Inferred 

reserves Total 

Remaining reserves of bituminous coal, January l, 1951 

(14 to 28 in. 51,390 1,693,930 2,963,850 4,709,170 

0 to (28 to 42 in. 270,040 2,572,080 874,000 3,716,120 

1,000 feet (42 in.+ 46_3, 960 1,311,130 100,670 1,875,760 

Total 7t55,390 5.577,140 3,938,520 10,301,050 

(14 to 28 in. --- 630 331,180 331,810 

0 to (28 to 42 in. --- 4,830 72,020 76,850 

2,000 feet (42 in.+ --- 33,640 32.300 65.940 

Total --- 39,100 435,500 474,600 

Total--------~----------------------- 785,390 5,616,240 4,374,020 10,775,650 

Original reserves of semianthracite 

(14 to 28 in. --- 30,940 23,880 54,820 

0 to (28 to ·42 in. --- 10,640 18,410 29,050 

1,000 feet (42 in.+ --- 126,850 144,900 271,750 

Total ------------------------------- --- l68__,_1J..2.0 187 190 355.620 

Mined and lost in mining,January l, 1951 --------------------------------------- 12,000 

Total remaining reserves of semianthracite, January l, 1951 -------------------- 343,620 

Total remaining reserves, all ranks, January l, 1951, ---------------------------- 11,119,270 

or a weight of 1, 742 tons per acre-foot. A specific 

gravity of 1. 28 is rather low, however, for typical 

bituminous coal in the ground. By assuming a specific 

gravity of 1. 32, or a weight of 1, 800 tons per acrefoot, which is more generally accepted as the average 

of typical bituminous coal in the ground, the West 

Virginia estimate would be increased 3 percent. 

The remaining reserves in Raleigh County as of 

January 1, 1949, were estimated by Dowd and others 

(1952) to total 2, 532, 384, 000 tons. In McDowell 

County the remaining reserves as of January 1, 1951, 

were estimated by Wallace and others (1952) to total 

2, 216, 691, 000 tons. These estimates, prepared as 

part of a program of the Bureau of Mines to investigate 

minable reserves of coking coal, include measured and 

indicated reserves in beds 14 inches thick or more. 

The coal in each county was assumed to weigh 1, 800 tons 

per acre-foot. The Bureau of Mines figures for Raleigh 

and McDowell Counties are not comparable with the 

West Virginia Survey figures because the Bureau of Mines 

figures are for remaining measured and indicated reserves only, whereas the West Virginia Survey figures 

are for original measured, indicated, and inferred 

reserves. 

Wyoming 

The original coal reserves of Wyoming, as estimated by Berryhill and others (1950), totaled 

121, 553,850, 000 tons, of which 13,234, 950,000 tons 

is bituminous coal and 108, 318, 900, 000 tons is subbituminous coal. According to the few available 

34 

analyses, a large tonnage of coal on the eastern side 

of the Powder River Basin is close to the dividing line 

between subbituminous coal and lignite, but it is included in this estimate with reserves of subbituminous 

coal. The areal distribution of coal in Wyoming is 

shown on a map by Berryhill and others (1951), which 

is complementary to the reserve report. 

The Wyoming estimate, which shows the coal 

reserves classified by counties and by townships, was 

based on published and unpublished reports of the U. S. 

Geological Survey; on publications of the Geological 

Survey of Wyoming; and on records made available to the 

U. S. Geological Survey by mining companies, oil companies, and private indiv.iduals. Approximately 53 percent of the total area of coal-bearing rocks in Wyoming 

was not included in the estimate because little or no 

information on the coal beds in these areas was available. 

The estimate of reserves in Wyoming should therefore 

be substantially increased as mapping and exploration 

continue. 

The minimum thickness of coal included in the 

Wyoming reserve estimate was 14 inches for bituminous 

coal and 2! feetfor subbituminous coal. The reserves 

of different ranks of coal were classified according to the 

following thickness ranges: 

Rank Thickness categories 

14 to 28 inches 

Bituminous coal----------------- 28 to 42 inches 

More than 42 inches 

2~ to 5 feet 

Subbituminous coal-------------- 5 to 10 feet 

More than 10 feet 
The assumed areal extent of each coal bed was determined according to the standard U. S. Geological Survey procedures. Coal in the narrow weathered zone at the 

outcrop was included in the assumed area of coal occurrence, as was coal under roads and railroads. All known areas of burned coal were excluded. 

estimates were based, into three additional categories-measured, indicated, and inferred-established according to the standard procedures of 

the U. S. Geological Survey. 

In calculating the reserve estimate, the 

bituminous coal in Wyoming was assumed to have 

a weight of 1, 800 tons per acre-foot, and the 

subbituminous coal was assumed to have a weight 

of 1, 770 ton per acre-foot. 

The Wyoming coal reserves were further classified 

in the following ranges according to thickness of overburden: 

0 to 1,000 feet 

1,000 to 2,000 feet 

2,000 to 3,000 feet 

The reserves were also divided, according to the 

relative abundance of reliable information on which the 

The accompanying table (see below) shows the 

estimated original coal reserves of Wyoming classified according to rank of coal, thickness of bed, 

thickness of overburden, and relative abundance of 

reliable information. 

Estimated original coal reserves of Wyoming 

(In thousands of short tons) 

Overburden 

0 to 

1,000 feet 

1,000 to 

2,000 feet 

2,000 to 

3,000 feet 

Thickness 

of bed 

(14 to 28 in. 

(28 to 42 in. 

(42 in.+ 

Total 

(14 to 28 in. 

(28 to 42 in. 

(42 in.+ 

Total 

(14 to 28 in. 

(28 to 42 in. 

(42 in.+ 

Total 

Total-------------------------------

Measured 

reserves 

Bituminous coal 

24,400 

149,610 

1,512,910 

1,686,920 

4,860 

21,840 

318,840 

345,540 

---

--- 30,140 

30,140 

2,062,600 

Subbituminous coal 

(2~ to 5 ft 7,890 0 to (5 to 10 ft 70,960 1,000 feet (10 ft + 1,473,670 

Total 1,552,520 

(2~ to 5 ft --- 1,000 to (5 to 10 ft 5,070 2,000 feet (10 ft + l_ti_80 

Total 6,850 

(2~ to 5 ft --- 2,000 to (5 to 10 ft --- 3,000 feet (10 ft + --- Total ---

Total------------------------------- 1,559,370 

Total, 

both ranks----------------------------- 3,621,970 

35 

Indicated 

reserves 

446,070 

680,760 

2,180 ,']50 

3,307,580 

143,590 

332,310 

1,50_1,040 

1,9~2,.940 

58,700 

98,350 

1,043,580 

l,200,b30 

6,491,150 

6,503,920 

9,151,400 

:Q,561,830 

31,217,150 

737,660 

673,090 

363,600 

1,774,350 

281,540 

266,210 

171,830 

719,5~0 

33,711,080 

40,202,230 

Inferred 

reserves 

57,050 

82,900 

593 460 

733,410 

276,060 

425,770 

967,600 

1,669,430 

294,480 

448,410 

1,535,470 

2,27~,360 

4,681,.200 

7,358,730 

15,428,480 

35,i48,700 

57,935,910 

2,871,010 

9,499,040 

498,300 

12,868,350 

810,180 

1,215,630 

218,380 

2,244,190 

73,048,450 

77,729,650 

Total 

527,520 

913,270 

4,28_7_.,120 

5,727,910 

424,510 

779,920 

2 _ti_93 1. 480 

3,997,910 

353,180 

546,760 

2,609,190 

3,509,130 

13,234,950 

13,870,540 

24,650,840 

52,184,200 

90,705,580 

3,608,670 

10,177,200 863~680 

14,649,550 

1,091,720 

1,481,840 

390 210 

2,963,770 

108,318,9oo 

121,553,850 
Other states 

In this report of progress on the U. S. Geological Survey's program to reappraise the coal reserves 

of the United States, it has not been possible to include new appraisals for all states. Nor has it been 

considered desirable to make arbitrary and. undocumented changes in the older estimates. For states 

not previously discussed, therefore, the estimates 

prepared by Campbell in the years prior to 1928 have 

been included in tables 1 and 2 for the sake of completeness, but they are shown in lower case letters to indicate their origin. 

In these older estimates of original reserves, the 

following minimum thicknesses were used for the different ranks of coal: 

Rank Minimum 

thickness 

Bituminous coal and anthracite-------------- 14 inches 

Subbituminous coal-------------------------- 2 feet 

Lignite------------------------------------- 3 feet 

The estimates were based on an assumed specific 

gravity of 1. 3, or a weight of 1, 770 tons per 

acre-foot, for coal of all ranks, and all coal to 

a depth of 3, 000 feet below the surface was included in a single category. 

As the presently active program of reappraising 

the coal reserves of the U. S. continues, new detailed 

estimates for other states will become available, thus 

increasing the accuracy and completeness of knowledge 

of the national coal resources. 

Alaska 

Coal is known to occur in substantial quantities at numerous places in Alaska.. Very little 

detailed mapping or exploration has been carried 

on in the coal-bearing areas, however, and only 

a generalized estimate of the total coal reserves 

in the Territory can be made at the present time. 

According to an estimate prepared in 1944 by 

Clyde Wahrhaftig of the Geological Survey, the 

total original coal reserves of Alaska. were inferred to be 107, 394, 000, 000 tons, (Buch, and 

others 1947, p. 235), of which 23, 800,000,000 tons 

is bituminous coal; 82, 594, 000, 000 tons, subbituminous coal and lignite; and 1, 000, 000, 000 tons, 

anthracite. 

The coal reserves of Alaska. cannot be classified 

by thickness of bed or overburden because of the scarcity 

of detailed information. Access to transportation facilities is the chief factor ;lffecting coal-mining development in Alaska, and the,reserve figures presented 

in the tabulation shown on page 37 and are therefore. 

classified by region and by accessibility to present 

railroads. 

By January 1, 1953, the total recorded production of coal in Alaska totaled 7, 138, 000 tons, 

most of which came from the Matanuska Valley 

and Nenana fields on the Alaska Railroad. High 

costs of mining and shipping limit Alaskan coal 

at present to use within the Territory. 

36 

POSSIBLE ADDITIONAL RESERVES NOT INCLUDED 

IN ESTIMATES 

In states for which modern, classified estimates 

have been prepared, large areas of coal-bearing rocks 

have been omitted from consideration for want of specific information about the thickness and continuity of 

the coal beds. In Wyoming, for example, 53. 5 percent 

of the known area of coal-bearing rocks was omitted, 

and in Montana, 9. 3 percent was omitted. When full 

and complete information is available about such areas 

the estimated coal reserves will be increased substantially. 

Because most mining and prospecting in the 

United States is done along surface outcrops, very 

little information is available about the occurrence of 

coal at depth, or at a distance of more than a few miles 

from the outcrops; and no information is available about 

reserves in the centers of the large coal basins. Therefore, most of the estimated reserves, particularly in 

the states for which modern, classified estimates are 

available, are confined to a narrow zone a few miles 

wide parallel to the outcrops of the individual coal beds. 

This is well illustrated by the fact that 87 percent of 

the reserves classified in figure 5B is less than 1, 000 feet 

below the surface. When exploration is pushed to 

greater distances from the outcrops, and to greater 

qepths, reserves should be increased correspondingly. 

Many known coal-bearing areas, particularly 

those remote from present means of transportation or 

centers of use, have been mapped or examined only in 

reconnaissance. Reserve estimates for such areas 

tend to be small because of the paucity of information, 

and because only the thicker and better beds are examined during the course of reconnaissance work. The 

extension of detailed mapping in such areas should, 

therefore, yield data that would permit an increase in 

reserve estimates. 

In many other areas, information about the thickness and nature of rocks between coal beds is so scanty 

that it is impossible to establish correlations between 

coal beds in different parts of an area. Where correlations cannot be established, estimated reserves are 

restricted to areas near the known outcrops. Where 

correlations can be established, reserves can be inferred to exist at greater distances between the outcrops, and the total estimated reserves tend to be 

larger. 

It is thus apparent that the newer estimates of 

reserves, based as they are on conservative assumptions, are minimum estimates, and will be increased 

in the future as additional information is acquired 

through geologic mapping and physical exploration. 

NEED FOR ADDITIONAL WORK 

The results of the current study of coal reserves 

in various states show clearly the need for additional 

mapping and exploration. Although the recent estimates 

are an improvement over previous ones, primarily because they are presented in carefully defined categories, 

they point to many obvious deficiencies in the state of 

knowledge about the distribution, extent, and correlation of coal beds as outlined in paragraphs above. 
Estimated original coal reserves of Alaska 

(In thousands of short tons) 

Within 40 miles of 

Accessible by present means of Remote from presRegion present means of transportation ent means of Total 

transportation but not immedi- transportation 

ately available 

Bituminous coal 

Arctic Ocean drainage -- --- --- 22,000,000 22,000,000 

Yukon and Kuskokwim 

drainage basins 1 ------ --- ( 2) --- --- Pacific Ocean drainage 

and Alaska 

Peninsula 3 ------------ 450,000 1,350,000 --- 1,800,000 

Total ----------------- 450,000 1,350,000 22,000,000 23,800,000 

Subbituminous coal and lignite 

Arctic Ocean draiqage -- --- --- 60,000,000 60,000,000 

Yukon and Kuskokwim 

drainage basins 1 ------ --- 400,000 --- 400,000 

Pacific Ocean drainage 

and Alaska J Peninsula-------------- 2,400,000 19,600,000 186,000 22,186,000 

Total ----------------- 2,400,000 20,000,000 60,186,000 82,586,000 

Lignite 

Southeastern Alaska ---- I 8,000 8,000 

Anthracite 

Pacific Ocean drainage 

and Alaska 

Peninsula 3 ------------ --- 1,000,000 --- 1,000,000 

Total, all ranks ----- 2,858,000 22,350,000 82,186,000 107,394,000 

1 Excludes areas south of the Tanana River tributary to the Alaska Railroad and the Richardson Highway. 2

Present, but quantity unknown. 3 Includes areas excluded in Yukon and Kuskokwim drainage basins. 

Full knowledge about the coal resources of the United 

States is thus dependent on a continuing, active program 

of detailed geologic mapping and exploratory drilling 

in the coal field areas, accompanied by periodic inventories of reserves. 

The cooperation between Government and Industry 

in the accumulation, preservation, and analysis of coal 

reserve data., which has been so effective in the preparation of recent reserve appraisals, should be strengthened and improved at every opportunity. 

UNITED STATES COAL COMMISSION COMMITTEE 

REPORT, 1922 

The recoverable coal reserves of the United States 

as of January 1, 1922, were estimated to be 1,634,130 million tons, by a committee established by the United States 

Coal Commission. This committee, the Engineers' 

Advisory Valuation Committee, was requested to estimate the market value of coal mines and of the coal in 

the ground. The Coal Commission did not accept the estimate of the valuation committee for use in their reports 

although permission was given for separate publication 

37 

by the committee (Am. Inst. Min. Met. Eng., 1924). 

The estimate of recoverable reserves prepared by the 

committee, now largely of historical value, was based 

on the estimate of original reserves prepared by 

Campbell and on estimates of several state surveys. 

These estimates were reduced to allow for future mining losses and to exclude "thin and unavailable coal. " 

No specific information as to the criteria used in reducing the basic original reserve figures is contained in the 

committee report. 'It is interesting to note, however, 

that if a 50 percent recovery is assumed, the recoverable reserves of the United States as of January 1, 1919, 

based on the estimate of remaining reserves by Campbell, 

totaled 1, 768 billion tons, whereas the recoverable reserves as of January 1, 1922, suggested by the valuation 

committee totaled 1, 634 billion tons. 

A few writers have implied that the valuation 

committee's estimate differed significantly from the 

Campbell estimate as they fail to emphasize the fact 

that the Campbell estimate was for original coal reserves in the ground, whereas the valuation committee's 

estimate was for recoverable reserves as of January 1, 

1922. The two estimates are in quite close accord 
when they are adjusted to the same basis of 

comparison. 

U. S. ARMY CORPS OF ENGINEERS, 1952 

A survey of the United States to determine general 

areas suitable for the location of synthetic liquid fuel 

plants was completed in 1952 under the auspices of the 

Corps of Engineers, Department ofthe Army (1952): The 

estimated recoverable reserves of coal in the United 

States as of January 1, 1949, considered during the course 

of the survey totaled about 170 billion tons, of which a 

maximum of 126 billion tons was deemed to be suitable 

for immediate large scale use in the manufacture of 

synthetic liquid fuels. The Corps of Engineers estimate 

of 170 billion tons for recoverable reserves is about 

18 percent of the Geological Survey estimate of almost 

950 billion tons presented in tables 1 and 2 of this report. 

The difference between the two estimates is explained 

by the different purposes for which they were intended, 

and the different assumptions on which they are based. 

The major objective of the Corps of Engineers survey 

was to outline large blocks of coal that would be immediately available for large-scale mining to supply hypothetical synthetic liquid fuel plants. The maximum depth 

of coal considered in the Corps of Engineers estimate, 

for example, is 1, 500 feet, whereas in the Geological 

Survey estimate the reserves of coal are computed in 

three categories; 0 to 1, 000 feet; 1, 000 to 2, 000 feet; 

and 2, 000 to 3, 000 feet. The minimum thickness of coal 

considered for underground mining in the Corps of 

Engineers estimate is 24 inches for bituminous coal, 

and 48 inches for lignite; whereas, the Geological Survey 

estimate includes in its several categories of thickness, 

bituminous coal in beds as thin as 14 inches and lignite 

in beds as thin as 30 inches. 

The Corps of Engineers figure is thus a conservative statement of coal that is known to be immediately 

available for use under present mining conditions. It 

is roughly comparable with the U. S. Geological Survey 

estimate for measured and indicated reserves in beds 

28 inches or more thick, and less than 1,000 feet below 

the surface. (See fig. 6.) 

The larger figure of the U. S. Geological Survey 

includes in separate categories reserves of both present 

economic interest and possible future usefulness, and 

thus provides a more comprehensive statement of information available about the total coal reserves of the 

United States. 

PEAT RESERVES 

Peat, the first stage in the metamorphism of plants 

to coal, is the partly carbonized remains of roots, trunks 

of trees, twigs, seeds, shrubs, grasses, and mosses 

that have been covered or saturated with water so that 

decomposition is arrested. It contains a large proportion 

of the carbon of the original vegetable matter, and the 

plant structures of which it is composed are generally 

visible without the aid of a microscope. In general, peat 

accumulates on poorly-drained land in regions of cool 

climate or high humidity, where evaporation is slow, 

and peat-forming plants may flourish. 

Peat is an important fuel in Europe, but only small 

quantities have been produced as commercial fuel in 

the United States because of the abundance and superiority of coal. The United States contains large deposits 

of peat, however, and it is produced commercially for 

a number of purposes other than as fuel. Air-dried 

38 

peat is a convenient source of concentrated organic 

matter, and it contains about 2 percent nitrogen. Its 

principal uses in the United States, therefore, are for 

soil improvement and as an ingredient in commercial 

fertilizers. According to Corgan and Chiriaco (195,2), 

194,416 short tons of peat were produced in this country 

in 1951. Of the total, 73 percent was used for soil 

improvement, 19 percent for mixed commercial fertilizers, and 8 percent for other purposes, which included 

litter for barns and poultry yards, use in nurseries and 

greenhouses, and packing material for plants, fruits, 

vegetables, eggs, and other fragile articles. 

The United States contained original known peat 

reserves totaling 13,827,000,000 short tons, calculated 

on an air-dried basis, as estimated in a detailed report 

on peat by Soper and Osbon (1922, p. 92-93). Of this 

total only about 2,000,000 tons was mined between 

1922 and 1951. The peat reserves occur primarily in 

local deposits distributed throughout two general regions. The northern peat region, which contains approximately 80 percent of the total reserves, includes 

Minnesota, Wisconsin, Michigan, easternSouthDakota, 

the northern parts of Iowa, illinois, Indiana, Ohio, and 

Pennsylvania, and New York, New Jersey, and the 

New England States. The Atlantic coastal region, which 

contains approximately 19 percent of the total reserves, 

includes the southern part of Delaware, the eastern 

parts of Maryland, Virginia, North Carolina, South 

Carolina, and Georgia, and all of Florida. Small deposits of peat also occur in a narrow belt of land adjoining the Gulf Coast; in the valleys of the Sacramento 

and San Joaquin Rivers and in Siskiyou, Los Angeles, 

Orange, and San Bernardino Counties, California; and 

in the basins of lakes and rivers in Oregon and Washington. 

The accompanying table by Soper and Osbon shows 

the known original reserves of peat in the United States, 

calculated on an air-dried basis, by regions and states. 

In addition to this general table, the report by Soper 

and Osbon includes tables of reserves classified by 

counties for the states having important peat reserves, 

as well as detailed descriptions of individual peat 

deposits. 

Known original reserves of peat in the United States, 

estimated on an air-dried basis, by regions and states 

(In thousands of short tons) - Region and Reserves Region and Reserves 

state state 

Northern region: Atlantic coastal 

Minnesota----- 6,835,000 region: 

Wisconsin----- 2,500,000 Virginia and 

Michigan------ 1,000,000 No. Carolina 700,000 

Iowa---------- 22,000 Florida------ 2,000,000 

Illinois------ 10,000 Other statesl 2,000 

Indiana------- 13,000 Total---- 2, 702,000 

Ohio--------- 50,000 

Pennsylvania- 1,000 Other regions: 

New York----- 480,000 Gulf Coast2-- 2,000 

New Jersey--- 15,000 California--- 72,000 

Maine-------- 100,000 Oregon and 

New Hampshire 1,000 Washington-- 1,000 

Vermont------ 8,000 Total---- 75,000 

Massachusetts 12,000 

Connecticut--· 2,000 Total, 

Rhode Island-· l 000 all 

Total----· 11,050,000 regions- 13,827,000 

1

Jncludes Delaware, Maryland, South Carolina, and Georgia. 2 Exclusive of Florida. 
WORLD COAL RESERVES 

Estimates of the remaining coal reserves of the 

world by continents and principal coal-producing 

countries are shown in table 4. The figures included 

in the table were taken from Statistical Year-books 

Nos. 4 and 5 of the World Power Conference (F. Brown, 

1948 and 1950) except for estimates of the United States, 

Alaska, Colombia, and Brazil, which were prepared 

by the U. '"S. Geological Survey. 

Most of the figures in the table are for remaining 

reserves as of different dates in the period between 

1913 and 1953; others are for origif'.al reserves. This 

minor discrepancy does not affect the relative standing 

of any continent or country to a sign~ficant deqree. 

All figures in the table are in metric tons, the 

standard unit for measuring coal in most countries. 

One metric ton is equivalent to 2, 205 pounds, or 

1. 1 short tons. 

With remaining reserves of 1, 723, 416 million 

metric tons of coal, as currently estimated, the 

United States appears to have 34. 4 percent of 

the total remaining world reserves of 5, 008,566 million tons. By comparison, the entire North 

American continent appears to have 38. 2 percent 

of the total, and Asia, including European Russia, 

appears to have 46. 0 percent. 

Table 4 gives only a very generalized comparison of the reserves in the principal coalproducing countries of the world. Because of the 

different methods of calculating coal reserves, the 

different standards of thickness and depth adopted, 

and the different dates for which estimates were 

made for individual countries, the figures shown 

in the table are comparable only to the extent 

that they show the general order of magnitude of 

the reserves in each country. In particular, the 

revisions in recent years of methods of calculating 

coal reserves by some countries, and continued 

adherence to older methods by others, mean that 

certain figures in the table are conservative and represent only immediately accessible proved coal in 

thick beds, whereas other figures are much more 

comprehensive and include total reserves in thick 

and thin beds without regard to quality, minability, 

or accessibility of the coal. 

Canada provides an example of the effect of 

changes in methods of calculating coal reserves. 

Figures published in 1913 gave Canada remaining 

reserves of 11 216, 770 million metric tons as of 

that year (Twelfth International Geological Congress, 

1913). In 1946 the remaining reserves in Canada 

were re-estimated at less than 10 percent of 

that amount, or only 89, 645 million metric tons 

(MacKay, 1947). The earlier estimate was made 

on general assumptions of continuity of coal beds 

which were based on few observations, and included statistical allowance for all possible coal 

to a minimum thickness of 1 foot and to a maximum depth of 4, 000 feet. The more recent estimate includes only known developed or explored 

coal beds, which, for reasons of thickness, quality, 

and extraction costs, were considered economically 

minable in 1946. Reserves for most other countries 

39 

shown in table 4 relate to all coal in the ground, 

irrespective of quality, minability, or accessibility, 

and many of these figures will no doubt be reduced in the future as more detailed information 

becomes available and more restricted methods of 

calculating reserves are adopted. 

RELATION OF COAL IN THE UNITED STATES TO 

OTHER FORMS OF ENERGY 

The industrial machine of the United States 

annually consumes prodigious quantities of energy. 

The mineral fuels and water power produced in 

1952, for example, contained heat energy equivalent to 8 horsepower per person per day, for 

the entire year. Furthermore, the production and 

use of energy is increasing annually at a very 

rapid rate. As shown in figure 8, the over-all 

use of energy in the United States has quadrupled 

in the last 50 years, and nearly doubled in the 

last 25 years. And the curve is still headed 

sharply upward. This upward surge in the use of 

energy is impelled partly by our rapidly growing 

population, which has doubled in the last 50 years, 

and partly by our increased reliance on machines 

and manufactured products. Considering the potential future increase both in population and in 

use of energy, no one can forecast with assurance 

the time when the ascending curve will level off. 

With consumption of energy in progress on such an 

enormous and ever increasing scale, it is interesting and instructive to review the position of 

coal in the total energy use pattern. 

During 1952, a year second only to 1951 

in the use of fuel in the United States, coal 

supplied only 34 percent of the total energy produced from all sources, while petroleum and 

natural gas together supplied a total of 61. 9 percent. The remaining 4. 1 percent was supplied 

by water power (U. S. Bureau of Mines, 1953). 

As shown in figure 9, the percentage of total 

energy supplied by coal has decreased steadily 

from about 90 percent in 1900 to the present 

record low of 34 percent. The percentage decrease 

in use of coal through the years has been accompanied by a corresponding percentage increase 

in the use of petroleum and natural gas, which 

have had greater consumer appeal because of their 

convenience, and which have filled a number of new 

uses not competitive with coal. Included in the 

percentage figures for petroleum and natural gas, 

for example, are gasoline and diesel oils used 

in automobiles and trucks, heavy oils used in 

road construction and maintenance, natural gas 

consumed in the manufacture of carbon black, 

and lubricants. 

The trend toward increased use of petroleum and natural gas is not expected to continue 

indefinitely. As the Nation's energy requirements 

increase, the reserves of petroleum and natural 

gas cannot be expected to increase proportionately and coal, or some other equally abundant 

and economical source of energy, must carry 

an increasing part of the load. 
Table 4.--Estimated remaining coal reserves of the world by regions and principal coal-producing 

countries 1 

Region and country 

(In millions of metric tons) 

Anthracite; bituminous and 

subbituminous 

coal 

Lignite and 

brown coal Total 

Percent 

of 

regional 

total 

Percent 

of 

world 

total 

Asia: 2 

U. S. S. R. ------------- 998,000 202,000 1,200,000 52.2 24.0 

China ------------------- 1,011,000 600 1,011,600 44.0 20.2 

India ------------------- 62,143 2,833 64,976 2.8 1.3 

Japan 3------------------ 16,218 473 16,691 .7 .3 

Others ------------------ 7, 214 349 7,563 .3 . 2 

Total --------------- _r--------::2~,--::-0-::::-9417-',:....::5:-=7-=-5 -+----2::::-:0::--/)6~, 25=-5=-+----::-2-=, 3=-=o~o--<-,n: 8:3:0::-':0:-------t-~l-=-oo=-.'--'::o:-+----T.'"?'"" 46.----::o=---

North America: 

United States 4------------ 1,303,066 420,350 1,723,416 90.2 34.4 

Alaska 5------------------ 6 22,498 6 74,915 97,413 5.1 2.0 

Canada 7------------------ 65 053 24 592 89,645 4. 7 l 8 

·rotal -------------- --~----:::-1__,, 3~9?::o:L;.;._, 61:::::::7~----=5==-=190:..!.;~ 57=--+---=-l-=~ 9~1:..::-o~, 4i:-::7~4~--l=-=o:-:::o:--=-: -!:--o +----::3;-;;:r-8: 2::::--

Europe: 

Germany ----------------- 279,516 56,758 336,274 51.0 6.7 

United Kingdom ---------- 172,200 (11) 172,200 26.1 3.4 

Poland ------------------ 80,000 18 80,018 12.1 1.6 

Czechoslovakia ---------- 6,450 12,500 18,950 2.9 .4 

France ------------------ 11,224 125 11,349 1.5 . 2 

Portugal ---------------- 8 6,036 8 4,200 10,236 1.7 .2 

Others 9------------------ 16,619 14,289 30,908 4.7 .6 

Total ----------- -----~---5:::=-::7=.:::2:-z-, o45~----~~'70:-1,~ ~·90::----+-------;6,.,-::5:-;:::9~, 9~3:;-;::5:-+-~10:-:::0~.~o+---:::l-::::::3-=-c.l~ 

Africa: 

Union of South Africa --- 68,014 0 68,014 97.2 1.4 

Others ~----------------- 1,720 210 1,930 2.8 (11) Total --------------- _l---------6,....:;~9~,-=7=-34r----+-----2-=-:l:=-:0:-+-----,.6..:::<9~, 9::-14::....r:4:-+---=-lo=o=-.--=o-+---'=--=..t..:l=-.-..4-

Australasia: 6 

Australia --------------- 13,900 6 39,200 53,100 99.0 l.l 

Others ~----------------- 57 489 546 1.0 (1~ Total ----------------~------=1=3:-, -=-=95~7::--+----3=9=-,-;6~~~9::----+-----=5=3~, 6~46....-+-----,l::-:O:-::O=. 7

0 +-----\.=~1-=. 1=---

South and Central America: 

Colombia 13 --------------- 10,000 0 10,000 72.8 .2 

g~!;~l-4================== 2,116 z i;~~~ i~: ~ (11) Total ----------------~--------l~~~;~~=~~~-----~4~---~1=3~,7=3=7~-~l=oo=-.~o:-+-~~~~11 \_.~2,-

World total ---------- 4,l54,66l 853,905 5,008,566 

1 Brown, Frederick, Statistical year-book of the World Power Conference, .No.4, Central office, World Power: Conference, London, 1948; No. 5, 

Central office, World Power Conference, London, 1950; with the exception of the United States, Alaska, Colombia, and Brazil. 2 Total for European U.S.S.R. included with Asiatic U.S.S.R. 3 lncludes Korea, Federation of Malaya, Manchuria, and Turkey. 4 Estimate of remaining reserves as shown in tables 1 and 2, convened to metric tons. 5 Estimate of original reserves as shown on page 3 71convened to remaining reserves in metric tons as of January 1, 1953. 6 Subbituminous coal tabulated with lignite and brown coal. 7 Includes only reserves of coal considered minable in 1946 estimate of the Canadian Geological Survey. 6 Figures may not include proved reserves. 9 Includes Austria, Belgium, Bulgaria, Denmark, Eire, Greece, Hungary, Italy, The Netherlands, Norway, Roumania, Sweden, and Yugoslavia. 10Includes Algeria, Belgian Congo, French Morocco, Madagascar, Nigeria, and Tanganyika. - 11 Negligible. 12 Includes New Zealand and New Caledonia. 13Singewald, Q. D.,_ Mineral resources of Colombia (other than petroleum): U. S. Geol. Survey Bull. _964-B, p. 94, 1950. 14Includes Peru, Honduras, and Brazil. Estimate of reserves in Brazil by MacKenzie Gordon, Geologist, U. S. Geological Survey, personal 

communication. 

40 

100 .. 0 
40,000 

I " 

35,000 

r 

30,000 

::::> 1- 25,000 

Total energy 

{including water power I 

at prevailing fuel equivalent) 

CD 

l.L. ~ 

........ 0 

CJ) 20,000 

z 

0 

_J 

...J 

0::: 15,000 

1- B'tuminous coal 

and lignite 

10,000 

5,000 

0 -- - 1899 1904 1909 1913 '18 '2.0 1925 1930 1935 1940 1945 1950 1955 

Figure 8. -Annual supply of energy from mineral fuels and water power in the United States, 1899-1952. 
Percent of 

total energy supplied 

100 

90 

80 

70 

~ 

60 

50 

40 

30 

~ 

............... 20 

10 

............ 

f!ituminous 

~ 

\ ;,o_pl 

r:J 

.·•· ..... ... 

~ ~~ . 

A ........... ...... ······ v~ 

------

~ 

' 

~ \ liqnite .... A 

~ 

~v v ~ 

~ .. ~ K .·· .... .. .·· . . ...... 

o\ev~.· .· .. ···. ~ 

. .. · 

pe': .... ·· .· .. ·· .. ·· / 

Natur~ ·~ / 

y 

Water Po 

~ 

wet ~-- _ .,.. ___ ~--- ----- -~ f::.= _/ ___ 0 

1900 1905 1910 1915 1920 1925 1930 1935 1940 1945 1950 

Figure 9. -Percentage of total energy supplied by mineral fuels and water power, 1900-1952. 

42 

1955 
The decrease in the percentage contribution 

of coal to the total consumption of mineral fuels in 

the United States has not been accompanied by a 

comparable decrease in the actual.production of coal. 

On the contrary, an all-time record was established 

in 1947 when 688 million tons of coal was mined. 

(See figure 8.) The trend of high production of coal 

during World War II and the years immediately following is similar, however, to the trend that took 

place during and after World War I, when the 

previous record was set in 1918 with a production 

of 678 million tons. The President's Materials 

Policy Commission (1952, p. 24, 25) has stated that 

coal may be expected gradually to take over a larger 

share of the energy load after 1975, at which time 

an ·annual coal production of 800, 000, 000 tons would 

not be an unreasonable expectation. 

Estimates of coai reserves cannot readily be 

compared with estimates of petroleum and natural 

gas reserves because differences in the mode of 

occurrence of these fuels necessitate different 

methods of calculating reserves. Coal occurs in 

stratified deposits in sedimentary rocks, and the 

individual beds maintain a fairly uniform thickness 

over relatively large areas. The t~al quantity of 

coal in the ground can thus be estimated with reasonable accuracy from geologic observations made 

at the outcrops of coal beds, in mines and prospect 

pits, and from evidence supplied by drilling operations. The total reserves of bituminous sandstone 

and oil shale can be estimated with similar accuracy 

because these substances also occur in stratified 

deposits, the thickness and lateral extent of which 

may be determined at many places by geologi_c and 

prospecting observations at the surface. 

Petroleum and natural gas, on the other· hand, 

are highly mobile substances. They move underground through minute openings in the rocks and 

accumulate only where traps, or barriers, prevent 

further migration. As a great variety of structural 

and stratigraphic relations create such traps, the 

total number existing in the widespread thick sequences of sedimentary rocks cannot be predicted 

accurately, nor can the ultimate amount of recoverable oil or gas contained in these traps be ascertained. As a result, only proved reserves, i. e., 

reserves in developed areas, can be estimated with 

any certainty for petroleum and natural gas. Consequently, the estimates tend to be conservative 

and they must be changed frequently to accord ~ith new discoveries, and new methods of recovery. 

Despite the recognized difficulty of comparing 

reserve estimates for the several mineral fuels 

it_ is possible to show the approximate relative ~ag­ mtude of reserves by reducing all estimates to a 

common Btu basis, and by making certain adjustments to allow for differences in the methods of 

making calculations. Estimates of the reserves of 

various fuels are thus presented in table 5 which 

shows in quadrillions of Btu the estimated 'recoverable reserves of coal, petroleum, natural gas, 

bitumen, and oil from oil shale in the United States 

43 

as of January 1, 1953. The table gives the reserves of these individual fuels according to two 

major points of view: Column 1, termed, "measured 

and indicated, " includes only reserves believed to 

be recoverable by current production methods, and 

at costs equal to, or only slightly in excess of 

present costs. Column 2, termed, "total-all 

·classes, " includes total measured, indicated, and 

inferred reserves, or the total potential reserves 

available for present and future use without regard 

to cost of recovery. The figures in column 1 are thus 

markedly more conservative than the figures in 

column 2. 

The figure of 5, 117 quadrillion Btu used for 

coal in column 1 of table 5 is based on 25 percent 

of the total recoverable reserves of each rank as 

shown in table L This fraction is intended to 

represent measured and indicated reserves in beds 

28 inches or more thick, and less than 2,000 feet 

below the surface. It was obtained from figure 6, 

which is based on a consideration of the distribution 

of reserves in ten states-Illinois,· Indiana~ Michigan, 

Montana, New Mexico, North Carolina, North Dakota, 

South Dakota, Virginia, and Wyoming-for which 

the reserves of coal have been classified according 

to the thickness of bed and overburden. As these 

ten states contain about 40 percent of the total reserves in tbe United States, and include coal deposits of diverse ages, ranks,and types, the average 

observed distribution of reserves in the selected restricted category in these states is believed to be 

reasonably typical of the United States as a whole. 

The figures used for petroleum and natural 

gas in column 1 of table 5, are based on proved 

reserves as currently estimated by the American 

Petroleum Institute and the American Gas Association (Oil and Gas Journal, 1953). The figures 

for other fuels are based on similar conservative 

assumptions as explained in the footnotes to the 

table. 

The figure of 20,469 quadrillion Btu used for 

coal in column 2 of table 5 is based on the total 

recoverable reserves shown in table 1. It includes measured, indicated, and inferred reserves 

in beds 14 inches or more thick, and beds to 

depths of 3, 000 feet below the surface. 

Several attempts have been made to prepare 

estimates for total (measured, indicated, and inferred) reserves of petroleum and natural gas. 

These estimates have been based on the assumption 

that the total volume of marine sedimentary rocks 

in the 'United States within range of exploration by 

drilling will yield petroleum and natural gas in 

amounts proportional to the yields obtained from 

the volume of rock thoroughly explored thus far. 

Although no special accuracy is claimed for the 

figures resulting from this method of analysis, the 

figures provide some basis for comparison. Weeks 

(1948, p. 1094) estimated the potentially recoverable 

reserves of petroleum in the United States, excluding the Continental Shelf, to be 110 billion 

barrels; and Pratt (Fanning, 1950, p. 151) using 
Table 5.--Total estimated recoverable mineral-fuel veserves of the United States, Jan. 1, 1953.1 

- Recoverable reserves Average annua'l January l, 1953 Percent production (In quadrillions· of Btu) of total 1940-49 Type of mineral fuel Measured Total fuel (In quadrillions and all reserves indicated classes of Btu) 

(column l) (column 2) (column 3) (column 4) 

Coal ----------------------~---------

2 5,117 3 20,469 84 16 

Petroleum --------------------------- 4 198 5 413? 2 ll 

Natural gas ------------------------- 6 200 7 487 2 5 Bitumen from bituminous 

sandstone ------------------------- 84 88 (e) ( 9) Oil from oil shale ------------------ 10150 11 3,000 12 ( 9) 

Total ------------------ 5,669 24,377 100 32 

1 Reserves and production figures converted to Btu according to the following heat values: anthracite, 12,700 Btu per pound; bituminous coal, 

13,000 Btu per pound; subbituminous coal, 9,500 Btu per pound; lignite, 6, 700 Btu per pound; petroleum, bitumen from bituminous sandstone, and oil from 

oil shale, 6,000,000 Btu per barrel; and natural gas, 1,000 Btu per cubic foot. 2 Twenty-five percent of reserves as shown in table 1, determined by consideration of ten states for which reserve.s have been classified by thickness 

of bed and overburden. The estimate is intended to show reserves of measured and indicated coal in beds at least 28 inches thick and under no more than 

2,000 feet of overburden. 3 From tables 1 and 2. 4 Proved reserves •. Estimate by the American Petroleum Institute, as reported in the Oil and Gas Journa\. v •. 51, no. 45, p. 78-79, March 16, 1953. 

Figure includes Btu equivalent of 5 billion barrels of natural•gas liquids •. 5 Recoverable reserves of petroleum remaining after subtracting petroleum production to January 1, 1953, from original petroleum reserves of 115 billion 

barrels, of which 100 billion barrels represent reserves of the United States exclusive of Continental Shelf, as estimated by W. E. Prart in Our oil resources, 

second _edit.l.on, edited by L. M. Fanning;· McGraw-Hill Book Company, New York, 1950; and 15 billion barrels represent reserves in the Continental Shelf, 

as published in a statement prepared by the U. S. Geological Survey at the request of the Committee on Interior and Insular Affairs, U.S. Senate, on Fuel 

reserves of the United States: Committee Print, 82 Cong., 1st sess.,. p. 32, 1951. 6 Proved reserves. Estimate by the American Gas Association, as reported in the Oil and Gas Journal, v •. 51, no. 45, p. 78-79, March 16, 1953. 7 Recoverable reserves of natural gas as of Jan. 1, 1953, obtained by subtracting production of 23 trillion cubic feet in 1950, '51, and '52 from estimate of 510 trillion cubic feet as of Jan. 1, 1950, as presented by L. F. Terry in The future supply of natural gas: Gas Age, v. 106, no. 9, p. 59 and 98, 

October 26, 1950. Figure includes Continental Shelf. 6 Fifty percent of estimated reserves of bitumen from bituminous sandstone in deposits near Vernal and Sunnyside, Utah; Casmalia, Santa Cruz, Edna, 

Sisquoc, Sulphur Mountain, and San Ardo, Calif.; and Uvalde, Tex. Estimate incomplete. 9 Negligible. , 10Sixty percent of reserves of oil in oil shale containing 30 gallons of oil per ton, 'as estimated by D. C. Duncan, U. S. Geological Survey. Personal 

communication. 11 Fifty percent of reserves of oil in oil shale deposits having an average content of 15 gallons of oil per tonr as estimated by D. C. Duncan, 

U. S. Geological Survey. Personal communication. 

essentially the same data, estimated the amount to 

be 100 billion barrels. 

The U. S. Geo~ogical Survey (1951) estimated 

the potential petroleum reserves of the Continental 

Shelf along Texas, Louisiana, and California to 

total about 15 billion barrels, based on consideration of the quantity of petroleum already discovered in nearby coastal belts of comparable size. 

On the basis of these three figures, the total 

potentially recoverable reserves of petroleum in 

the United States, including the nearer, more 

accessible parts of the Continental Shelf may be 

assumed for the purpose of this discussion to be 

about 115 billion barrels. This assumed figure is, 

of course, intended to represent the total, ultimately recoverable original reserves before production began; that is to say, past production, 

present proved reserves, and assumed future discoveries. To make it comparable with figures 

44 

for total reserves of coal and other fuels as of 

January 1, 1953, it must be reduced to allow for 

production to January 1, 1953. The figure for 

petroleum reserves used in column 2 of table 5 

was thus obtained by subtracting the total recorded 

production of petroleum to January 1, 1953, from 

the assumed figure of 115 billion barrels. 

Using the same general methods as those 

used for arriving at the total oil reserves, 

Terry (1950) estimated the potential recoverable 

natural gas reserves of the United States, including the Continental Shelf, to total 510 trillion 

cubic fes;t, as of January 1, 1950. After subtracting production of 23 trillion cubic feet in 

1950, 1951, and 1952, the estimated potential recoverable natural gas reserves of the United States, 

as of January 1, 1953, total 487 trillion cubic feet. 

Terry's estimate for natural gas reserves was. 

used as the source of the figure shown in column 2 

of table 5. 
Considering the ever-present possibility of 

future additions to petroleum and natural gas reserves beyond those allowed for by a statistical 

analysis of currently available data, it is likely that 

these figures are too small rather than too large. However, they are the best figures available for comparison 

with estimates of total coal reserves. 

The dominance of coal in the total fuel picture 

is clear.ly shown in both columns 1 and 2 of table 5. 

Reducing the figures in column 2 to percent as 

given in column 3, coal is seen to represent 84 percent of the total reserves of fuel in the United States 

whereas, petroleum and natural gas together repre- ' 

sent only 4 percent. In view of the relatively large 

reserves of coal, and the relatively small reserves 

of petroleum and natural gas, it is instructive to 

consider the rates at which these fuels are currently 

being produced and used. In column 4 of table 5 

it will be noted that on a Btu basis the combined 

average annual production of petroleum and natural 

gas during the period 1940-49 equals the average 

annual production of coal. This average rate has 

been exceeded every year since 1945, and by 1952, 

petroleum and natural gas together supplied 61. 9 percent of the total energy obtained from all sources. 

These rates are far out of proportion to the 

known or inferred total reserves of petroleum 

and natural gas, and point to the day when we 

shall be forced to place greater reliance on coal, 

or else develop and vastly expand other sources 

of energy. 

LIFE EXPECTANCY OF UNITED STATES FUEL 

RESERVES 

Because of the many imponderable factors 

to be taken into consideration, it is impossible 

to estimate the life expectancy of fuel reserves 

in the United States with -any degree of accuracy. 

Even so basic a factor as the magnitude of the 

reserves is at best but an approximation, based 

on data currently available, and is therefore 

subject to change in the future. Other factors, 

such as the observed increase in population and 

use of energy, increase in efficiency in production and use of fuel, imports of fuel oil, and 

the possibility of developing new sources of 

energy, are highly variable and so closely related as to defy precise analysis. A few of 

these factors are discussed briefly in the following paragraphs as a means of emphasizing the 

uncertainty attending statements about the ·life 

expectancy of fuel reserves. 

The estimates of reserves presented in 

this report and used as a basis fo:r this discussion of life expectancy are based on information currently available. The infQrmation is 

admittedly incomplete, and with the experience 

of the past as a guide it seems safe to predict 

that the t9tal reserves of all fuels, particularly 

rP.serves of petroleum and natural gas, ultimately will be found to be larger than the present figures suggest. Because of the conservative 

45 

assumptions now being employed, the newer 

coal reserve estimates tend to be smaller than 

older estimates, and the total figure for the 

United States, based as it is on both old and 

new figures, is subject to further decrease in 

the immediate future. Once a m1mmum conservative figure is established for United States 

coal reserves, however, it is likely that subsequent exploration and development will increase 

the estimate, and that the total coal reserves 

ultimately will be found to be larger than the 

present figure. The life expectancy of all fuels 

is therefore subject to increase as additional 

knowledge is acquired about the magnitude of 

reserves. 

In considering the life expectancy of fuel 

reserves it is necessary to make generous 

allowance for the probable future increase in 

use of fuel. The only yardstick for this purpose 

is the experience of the past 50 years, which 

shows an unprecedented fourfold increase, due 

in part to an increase in population, and in 

part to an increase in the per-cap1ta use of 

energy. It ls difficult to project such a steeply 

rising trend far enough into the future to be 

meaningful. 

In the production of petroleum, recoverability has increased steadily throughout the 

years, and this is one of the reasons why proved 

reserves of petroleum tend to increase annually. 

Similarly, many methods have been devised to 

improve recoverability in coal mmmg. In this 

report the recoverable reserves of coal are 

assumed to be only 50 percent of the total reserves in the ground, which factor accords. with 

the past average experience in a number of 

mining districts. The recoverability from a 

number of individual mines is much higher than 

50 percent, however, and it is believed that 

the over-all recovera,bility in coal mining could 

be increased considerably, perhaps to 65 percent. Also, many thin coal beds, not now considered to be recoverable, or areas now considered to be mined out, may ultimately be included as recoverable reserves if underground 

gasification techniques, now in the experimental 

stage, can be improved (Fies, 1952). Any 

increase in the recoverability of fuels can be 

expressed directly as an increase in reserves. 

Improvement in the use of fuels is illustrated by the marked economies introduced in 

the production of electricity at electric utility 

plants in the United States. In 1920, for example, an average of 3 pounds of coal was 

required to produce .1 kilowatt-hour of electricity, whereas, by , 1951, only 1. 14 pounds was 

required (U. S. Bureau of Mines, 1952). Possible 

future improvement in the use of fuels would 

permit a comparable increase in estimates of 

life expectancy of reserves. 

The form in which the energy in coal is used 

is perhaps the largest indeterminable factor that enters 
into any consideration of the life expectancy of coal 

reserves. If the future uses of coal are considered 

for a. long period, it is apparent that for many years 

to come, the uses will be the same as at present. 

Wrather and others (1950), however, have pointed 

out that the United States i_s committing itself to a 

liquid- and gaseous-fueleconomy, and ultimately cDal 

may become an important material for synthesis of 

these fuels in addition to filling the requirements for 

solid fuel. If such conversion of coal becomes general, 

the need for coal will be enormous for, on the basis 

of present• technology, about 50 percent of the potential 

energy in coal is lost in the conversion to liquid fuel 

(Ayres and Scarlott, 1952, p. 113). 

The large reserves of petroleum in the Near East, 

Venezuela, Mexico, and elsewhere are needed only in 

small quantities at the points of origin. Some of this 

petroleum is finding, and probably will continue to 

find, a market in the United States, which is by far the 

largest consumer of petroleum products in the world. 

In 1952 such imports of. crude and residual oil and 

distillate represented a record of 5. 2 percent of our 

total fuel needs (U. S. Bureau of Mines, 1953). Such 

foreign imports may greatly lengthen the life expectancy of domestic fuels. 

As reserves of coal, petroleum, natural gas, and 

other fossil fuels approach exhaustion, we shall be 

forced to place increased reliance on other energy 

sources like atomic energy, solar energy, earth heat, 

and tides. Experiments and studies in the use of 

atomic energy to produce electricity are in progress 

on several fronts, and much thought has been devoted 

to the possibility of harnessing solar energy. Ayres 

and Scarlott (1952, p. 279-283) believe that solar 

energy deserves greater attention than it has yet received because it is the only constant energy source 

available for large scale development. The life expectancy of coal, petroleum, natural gas, and other 

fossil fuels will be lengthened to the extent that through 

progress in research these other energy sources can 

be utilized. 

Appraisal of the life expectancy of any individual 

fuel is further complicated by the fact that most fuels 

can be used interchangeably, and at most installations 

the choice of fuel is determined largely by cost. The 

preferred position of petroleum and natural gas in the 

fuel economy, which is due to the present abundance, 

comparative economy, and convenience of these fuels 

will, therefore, continue as long as new petroleum and 

natural gas fields are discovered in the United States, 

and as long as imported petroleum is available in domestic markets. On the other hand, as petroleum and 

natural gas ultimately become less abundant, and hence 

more expensive than coal, many users of these fuels 

will convert to coal. Thus, l.ong before petroleum and 

natural gas reserves in the United States are exhausted, 

increasing reliance will need to be placed on other 

energy sources, a trend in which coal probably will 

contribute substantially. This period of transition may 

be greatly lengthened by utilization of imported supplies 

of petroleum, and it will be obscured by fluctuations 

in the economic cycle and by irregularities in the rate 

of discovery of new petroleum and natural gas fields. 

Because the life expectancy of petroleum and .natural 

gas reserves will be greatly extended as the relative 

use of coal and otl:rer energy sources is increa:::;ed, 

46 

and because of the possibility of future additions to 

reserves of petroleum, natural gas, and coal, an estimate of the life expectancy of any of these fuels is 

subject to serious question. 

Although it is thus impossible to predict the life 

expectancy of coal and other mineral fuels, the ratios 

between reserves and recent annual production provide 

figures that are somewhat more meaningful for 

comparative purposes than the reserve figures alone. 

The presently estimated total recoverable reserves 

of coal in the United States, for example, ·are 

1, 279 times the average annual production during 

the period 1940-1949; a figure that is many times 

larger than the ratios obtained from presently estimated total recoverable reserves of petroleum and 

natural gas. 

Similarly, measured and indicated coal reserves 

in beds 28 inches or more thick and less than 2,000 feet 

below the surface are 320 times the average annual 

production during the. period, 1940 to 1949; whereas 

the proved reserves of petroleum are only 18 times 

the average annual production, and the proved reserves of natural gas are only 40 times the average 

annual production. 

From consideration of the possible trends 

in the use of these fuels it is apparent that 

their probable life expectancy is quite different 

from the simple ratios of present production to 

reserves. Petroleum and natural gas certainly have 

a much longer life expectancy than the ratios indicate, 

and coal reserves, conversely, may have a shorter 

life expectancy. 

In the long history of human affairs, coal, 

petroleum, and natural gas have been used in 

large quantities only in the last 50 years. However large the reserves of these fuels may seem 

at present, the quantities are quite meager when 

compared with the life expectancy and the predictable future needs of the human race. In analyzing 

the life expectancy of the United States fuel reserves, Ayres and Scarlott (1950, p. 162) conclude 

that the mineral fuels alone can supply our future 

needs for a short period of 75 to 250 years. In 

analyzing the life expectancy of world fuels reserves, 

Hubbert (1951) sees the present growth of population 

and use of energy from the mineral fuels as being unprecedented in the history of human affairs, 

and impossible of continuation beyond a few hundred 

years. Ultimately, he believes, population growth 

must level off, and other sources of energy must 

be made available if we are to continue the comfortable standard of living now enjoyed through use 

of the mineral fuels. 

The predictions that the mineral fuels have a 

life expe~tancy of only a few hundred years are not 

intended to be precise, or discouraging in their outlook for the future. They are intended merely to show 

the approximate order of magnitude of the time during 

which an advanced technology must develop and 

harness new sources of energy. During the period 

of such development we have the comforting assurance that our substantial reserves of coal will meet 

all possible fuel needs. 
SELECTED BIBLIOGRAPHY 

Abernathy, G. E., Jewett, J. M., and Scho~we, W. H., 

1947, Coal reserves i.n Kansas: State Geol. Survey 

Kansas Bull. 70, pt. 1. 

American Institute of Mining and Metallurgical Engineers, 1924, Valuation of coal mining properties in 

the United States, report of the engineers 1 advisory 

valuation committee of the United States Coal Commission: Trans. 70, p. 794-804. 

American Society for Testing Materials, 1939, Standard specifications for classification of coals by rank : 

(A. S. T. M. Designation: D388-38): 1939, Book of 

A. S. T. M. Standards, pt. 3, p. 1-6. 

Ashley, G. H., 1898, The coal deposits of Indiana: 

Indiana Dept. Geology and Natural Resources 

23d Ann. Rept. 

1908, Supplementary report (to report of 

-1::-:8""'9"""8,....)-o-n-the coal deposits of Indiana: LYJ.diana Dept. 

Geology and Natural Resources 33d Ann. Rept. 

-=--__,._1926, Topographic and geologic atlas of 

Pennsylvania, no. 65, Punxsutawney quadrangle: 

Pennsylvania Geol. Survey, 4th ser. 

__,=--__,.-1940, Topographic and geologic atlas of 

Pennsylvania, no. 75, Curwensville quadrangle: 

Pennsylvania Geol. Survey, 4th ser. 

--:--r;----::-~1944, Pennsylvania 1 s mineral heritage, 

pt. 2, Mineral resources, Pennsylvania Dept. 

Internal Affairs, Harrisburg. 

-=----1945, Anthracite reserves: Pennsylvania. 

Topog. and Geol. Survey Progress Rept. 130. 

Ashmead, D. C., 1926, Anthracite losses 9,nd reserves 

in Pennsylvania: Pennsy 1 vania Topog. and Geol. 

Survey Bull. MS. 

Averitt, Paul, and Berryhill, L. R., 1950, Coal resources of the United States, a progress report, 

November 1, 1950: U, S. Geol.Survey Circ. 94. 

Ayres, Eugene, and Scarlott, C. A. , 1952, Energy 

)sources-the wealth of the world, McGraw-Hill 

Book Co., New York. 

Berryhill, H. L., Jr., Brown, D. M., Brown, Andrew, 

and Taylor, D. A., 1950, Coal reso'urces of Wyoming: U. S. Geol. Survey Circ. 81. 

Berryhill, H. L., Jr., Brown, D. M., Burns, R. N., 

and Combo, J. X., 1951, Coal resources map of 

Wyoming: U. S. Geol. Survey Coal IDv. Map C 6. 

Berryhill, L. R., and Averitt, Paul,. 1951, Cokingcoal deposits of the western United States: U. S. 

Geol. Survey Ci:rc. 90. 

Brant, R. A., 1953, Lignite resources of North 

Dakota: U. S. Geol. Survey Circ. 226. 

Brown, Andrew, Berryhill, H. L., Jr., Taylor, D. A., 

and Trumbull, J. V. A., 1952, Coal resources of 

Virginia: U. S. Geol. Survey Circ. 171. 

Brown, Andrew, Culbertson, W. c:, Dunham, R. J. , 

Kepferle, R. C., and May, P. R., in preparation, 

Selected deposits of strippable coal in southern 

Custer and northern Powder River Counties, Mont. : 

U. S. Geol. Survey Bull. 995-E. · 

Brown, D. M., 1952, Lignite resources of South 

Dakota: U. S. Geol. Survey Circ. 159. 

Brown, Frederick, 1948, Statistical year-book of the 

World Power Conference, no. 4, Central office, 

World Power Conference, London. 

___,=-----::::-1950, Statistical year-book of the World 

Power C.onference, no. 5, Central office, World 

Power Conference, London. 

47 

Buch, J. W., Hendricks, T. A., and Toenges, A. L., 

1947, Coal, in Mineral position of the United States: 

Hearings before a subcommittee of the Committee on 

Public Lands, U. S. Senate, 80th Cong., 1st sess., 

p. 231-235, May 15, 16, and 20. 

Butts, Charles, and Gildersleeve, Benjamin, 1948, 

Geology and mineral resources of the Paleozoic 

area in northwest Georgia: Georgia Geol. Survey 

Bull. 54. 

Cady, G. H., 1915, Coal resources of District 1 

(Illinois): Illinois Min. Inv. Bull. 10. 

1916, Coal resources of District VI 

-=(I=ll~in-o--=i,.....s..-): Illinois Min. Inv. Bull. 15. 

1917, Coal resources of District .II -"""(I""'ll~in-o-=i,.....s'): Illinois Min. Inv. Bull. 16. 

1919, Coal resources of District V --;:;(I~ll;-:-i-no-i:-s'): Illinois Min. Inv. Bull .. 19. 

1921, Coal resources of District IV 

-r.(I""'ll~in-o--=i,.....s'): Illinois Min. Inv. Bull. 26. 

---:-:--:--,.....1944, Coal resources based on information 

obtained from rotary drilling: Illinois Geol. Survey 

Rept. Inv. 93. 

1946, Content, conduct, and results of 

-"""Il~l-:-in-o--=i,...s-c-oal resources inventories: Paper delivered 

at Illinois Coal Research Conference, Oct. 23-24. 

-=-=---=-:-""""1949, Coal resources of Franklin County, 

Ill.: Illinois Geol. Survey Circ. 151, p. 65-76. 

Cady, G. H., and others, 1953, Minable coal reserves of Illinois: Illinois Geol. Survey Bull. 78. 

Clark, F. R., 1917, Original coal content of the fields, 

in Bownocker, J. A., The coal fields of Ohio: U. S. 

Geol. Survey Prof. Paper 100, p. 88-96. 

(Reprinted, 1929.) 

Cohee, G. V., Burns, R. N., Brown, Andrew, 

Brant, R. A., and Wright, Dorothy, 1950, Coal 

resources of Michigan: U. S. Geol. Survey Circ. 77. 

Combo, J. X., Brown, D. M., Pulver, H. F., and 

Taylor, D. A., 1949, Coal resources of Montana: 

U. S. Geol. Survey Circ. 53. 

Combo, J. X., Holmes, C. N., and Christner, H. R., 

1950, Map showing coal resources of Montana.: 

U. S. Geol. Survey Coal Inv. Map C 2. 

Corgan, J. A., and Chiriaco, G. V., 1952, Peat in 

the United States in 1951: U. S. Bur. of Mines 

Mineral Market Rept. No. 2078. 

Corps of Engineers, Dept. of the Army, 1952, The 

synthetic liquid fuel potential of the United States. 

Culbertson, W. C. , in preparation, Strippable lignite 

deposits west of the Yellowstone River in southern 

Richland and northern Dawson Counties, Mont.: 

U. S. Geol. Survey Bull. 995-H. 

Culver, H. E., 1925, Coal resources of District III 

(Illinois): Illinois Min. Inv. Bull. 29. 

Dowd, J. J., Toenges, A. L., Abernethy, R. F., 

and Reynolds, D. A. , 1952, Estimate of known 

recoverable reserves of coking coal in Jeffe'rson 

County, Pa.: U. S. Bur. Mines Rept. Inv. 4840. 

Estimate of known recoverable reserves 

-o-f::--co""""'k,....,i,__n-g coal in Knott County, Ky. : U. S. Bur. 

Mines Rept. Inv. 4897. 

Estimate of known recoverable reserves 

-o-:f:-c-o--=k--=i-n-g coal in Raleigh County, W. Va. : U. S. 

Bur. Mines Rept. Irw. 4893. 

Dowd, J. J., Turnbull, L. A. , Toenges, A. L., 

Abernethy, R. F., and Reynolds, D. A., 1951, 

Estimate of known recoverable reserves of coking 

coal in Armstrong County, Pa.: U. S. Bur. Mines 

Rept. Inv. 4801. 
Dowd., J. J., Turnbull, L. A., Toenges, A. L., 

Abernethy, R. F., and Reynolds, D. A., 1951, 

Estimate of known recoverable reserves of coking 

coal in Fayette County, Pa.: U. S. Bur. Mines 

Rept. Inv. 4807. 

--=-___,...,--·Estimate of known recoverable reserves 

of coking coal in Floyd County, Ky. : U. S. Bur. 

Mines Rept. Inv. 4813. 

---::-----:,-,--Estimate of known recoverable reserves 

of coking coal in Pike County, Ky.: U. S. Bur. 

Mines Rept. Inv. 4792. 

---::---,-,--·Estimate of known recoverable reserves 

of coking coal in Westmoreland County, Pa.: U. S. 

Bur. Mines Rept. Inv. 4803. 

Dowd, J. J., Turnbull, L. A. , Toenges, A. L., 

Cooper, H. M., Abernethy, R. F., Reynolds, D. A., 

and Fraser, Thomas, 1950, Estimate of known recoverable reserves of coking coal in Cambria County, 

Pa.: U. S. Bur. Mines Rept. Inv. 4734. 

Dowd, J. J., Turnbull, L. A., Toenges, A. L., 

Cooper, H. M., Abernethy, R. F., Reynolds, D. A., 

and Crentz, W. L. , 1950, Estimate of known recoverable reserves of coking coal in Indiana County, 

Pa.: U. S. Bur. Mines Rept. Inv. 4757. 

Eavenson, H. N., 1946, Wasting a valuable national 

resour:ce (bituminous coal): Am. Inst. Min. Met. 

Eng. Trans., v. 168, p. 11-14. 

Fanning, L, M., 1950, Our oil resources, 2d ed., 

McGraw-Hill Book Co., New York. 

Fieldner, A. C., Rice, W. E., and Moran, H. E., 

1942, Typical analyses of coals of the United States: 

U. S. Bur. Mines Tech. Paper 446. 

Fieldner, A. C., 1950, Coal for coke production: 

U. S. Bur. Mines Inf. Circ. 7559. 

Fies, M. H., 1952, unpublished, A review of the experiments throughout the world in the underground 

gasification of coal, paper presented at the Annual 

Meeting of the Am. Inst. Min. Met. Eng., NewYork, 

February, 1952. 

Flint, N. K., 1951, Geology of Perry County: Ohio 

Geol. Survey, 4th ser., Bull. 48. 

Headlee, A. J., and Nolting, J. P., 1940, Characteristics of minable coals of West Virginia: West 

Virginia Geol. Survey, v. 13. 

Hendricks, T. A., 1939, Energy resources and 

national policy: Rept. of Energy Resources Committee to National Resources Committee, 76th Cong., 

1st sess., H. Doc. 160, p. 281-286, January. 

Hickok, W. 0., IV, and Moyer, F. T., 1940, Geology 

and mineral resources of Fayette County, Pa. : 

Pennsylvania Geol. Survey, 4th ser., Bull. C 26. 

Hinds, Henry, 1913, The coal deposits of Missouri: 

Missouri Bur. Geology and Mines, 2d ser., v. 11. 

Hubbert, M. K., 1951, Energy from fossil fuels: 

Smithsonian Institution, Ann. Rept., 1950, p. 255-271. 

Johnson, V. H., 1946, Coal deposits on Sand and Lookout Mountains, Dade and Walker Counties, Georgia: 

U. S. Geol. Survey Preliminary Map. 

Kay, F. H., 1915, Coal resources of District VII 

(Illinois): Illinois Min. Inv. Bull. 11. 

Kay, F. H., and White, K. D., 1915, Coal resources 

of District VIII (Illinois): Illinois Min. Inv. Bull. 14. 

Kepferle, R. C., in press, Selected deposits of 

strippable coal in Rosebud County, Mont. : U. S. 

Geol. Survey Bull. 995-I. 

Koenig, R. P., 1950, Economics and technique of strip 

coal mining, in coal and metal mining: Colorado 

School of Mines Quart., v. 45, no. 2 B, p. 27-39. 

48 

Lesley, J. P., D'Invilliers, E. V., andSmith, A. D. W., 

1895, Pennsylvania Geol. Survey, 2d ser. , Summary, 

Final report, v. 3., pt. 1, p. 2147-2152. 

McCallie, S. W., 1904, A preliminary report ori the 

coal deposits of Georgia: Georgia Geol. Survey 

Bull. 12. ·· 

MacKay, B. R., 1947, Coal reserves of Canada: 

Rept. of Royal Commission on Coal, 1946. 

May, P. R. , in preparation, Strippable lignite deposits 

in the Wibaux area, Dawson, Richland, and Wibaux 

Counties, Mont., and Golden Valley County, N. Dak.: 

U. S. Geol. Survey Bull. 995-G. 

Oil and Gas Journal, 1953, v. 51, no. 45, p. 78-79, 

March 16. 

President's Materials Policy Commission, 1952, Resources for Freedom, The outlook for energy 

sources: v. 3, p. 24-31. 

Price, P. H., Tucker, R. C. , and Haught, 0. L., 

1938, Geology and natural resources of West 

Virginia: West Virginia Geol. Survey, v. 10. 

Ray, F. A., 1929, The Ohio coal supply and its exhaustion, in Bownocker, J. A., and Dean, E. S.,~ 

Analyses of the coal of Ohio: Ohio Geol. Survey, 

4th ser. , Bull. 34. 

Read, C. B., Duffner, R. T., Wood, G. H., and 

Zapp, A. D. , 1950, Coal resources of New Mexico: 

U. S. Geol. Survey Circ. 89. 

Reese, J. F., and Sisler, J. D., 1928, Bituminous 

coal fields of Pennsylvania: Pennsylvania Topog. 

and Geol. Survey Bull. M6, Coal resources, p. 1-9. 

Reinemund, J. A. , 1949, Deep River coal field, 

Chatham, Lee, and Moore Counties, N. C.: U. S. 

Geol. Survey Preliminary Map. 

--~::-:--,....,in preparation, Geology of the Deep River 

coal field, N. C. : U. S. Geol. Survey Prof. Paper 246 

Rothrock, H. E., 1950, A summary and critique of 

the estimates of Pennsylvania anthracite reserves, 

in Symposium on mineral resources in Pennsylvania: 

Pennsylvania Acad. Sci. Proc., v. 24, p. 192-197. 

Schoewe, W. H., 1951a, Current coal research-coal 

geology in Kansas~ Econ. Geology, v. 46, no. 8, 

p. 852-856, December. 

----,---.,....1951b, Coal resources of the Permian 

system in Kansas: State Geol. Survey Kansas Bull. ~ 0, 

pt. 3. 

----,----..,.,_1952, Coal resources of the Cretaceous 

system (Dakota formation) in central Kansas: 

State Geol. Survey Kansas Bull. 96, pt .. 2. 

Shaffner, M. N. , 1946, Topographic and geologic 

atlas of Pennsylvania, no. 55, Smicksburg quadrangle: Pennsylvania Geol. Survey, 4th ser. 

Smith, A. D. W., 1893, Report of Pennsylvania Coal 

Waste Commission. 

Smith, G. 0., and others, 1913, The classification 

of public lands: U. S. Geol. Survey Bull. 537, 

p. 88. 

Smith, w .. H., Brant, R. A. , and Amos, Fred, 1952, 

The Meigs Creek No. 9 coal bed in Ohio, pt. 1, 

Geology and reserves; Ohio Geol. Survey Rept. 

Inv. 17, p. 1-36 [1953]. 

Soper, E. K., and Osbon, C. C., 1922, The occurrence and uses of peat in the United States: 

U. S. Geol. Survey Bull. 728. 

Spencer, F. D., 1953, Coal resources of Indiana: 

U. S. Geol. Survey Circ. 266. 

Spencer, F; D., and Erwin, M. I., 1953, Coal resources of Colorado: U. S. Geol. ·Survey 

Circ. 258. 
Steel, A. A., 1910, Coal mining in Arkansas, pt. 1: 

Arkansas Geol. Survey. 

Sullivan, J. W., 1942, The geology of the Sand-Lookout Mountain area, northwest Georgia: Georgia Div. 

Geology Inf. Circ. 15. 

Terry, L. F., 1950, The future supply of natural gas: 

Gas Age, v. 106, no. 9, p. 58-60, 98, 100, 102. 

Toenges, A. L., Turnbull, L. A., Williams, Lloyd, 

Smith, H. L., 0 1Donnell, H. J., Cooper, H. M., 

Abernethy, R. F., and Waage, Karl, 1949, Investigations of the lower coal beds in Georges Creek 

and north part of Upper Potomac basins, AHegany 

and Garrett Counties, Md.: U. S. Bur. Mines 

Tech. Paper 725. 

Toenges, A. L. , Williams, Lloyd, Turnbull, L. A. , 

Parks, B. C., 0 1Donnell, H. J., Abernethy, R. F., 

Ode, W .. H., and Waage, Karl~ 1952, Castleman 

Basin, Garrett County, Md.: U. S. Bur. Mines 

Bull. 507. 

Twelfth International Geological Congress·, 1913, The 

coal resources of the world: Inquiry made on 

.initiative of executive committee, Morang and Co. 

Ltd. , Toronto. 

49 

U. S. Bureau of Mines, 1952, Bituminous coal and 

lignite in 1951: U. S. Bur. Mines Mineral 

Industry Surveys, Mineral Market Rept. No. 2102, 

October 27. 

____,,...............,...,.-_,1953, Production of bituminous coal and 

lignite: U. S. Bur. Mines Mineral Industry Surveys, 

Weekly Coal Rept. , Jan. 30. 

U. S. Geological Survey, 1951, Fuel reserves of the 

United States: Statement prepared at request of 

Committee on Interior and Insular Affairs, U. S. 

Senate, 82d Cong., 1st sess., Committee Print. 

Wallace, J. J., Dowd, J. J., Travenner, W. H. , 

Provost, J. M., Abernethy, R. F., and Reynolds, 

D. A. , 1952, Estimate of known recoverable reserves of coking coal in McDowell Co. , W. Va. : 

U. S. Bur. Mines Rept. Inv. 4924. 

Weeks, L. G., 1948, Highlights on 1947 developments 

in foreign petroleum fields: Am. Assoc. Petroleum 

Geologists Bull., v. 32, no. 6. 

Wrather, W. E., ~oyd, James, Smith, N. L., 

and Ayers, Eugene, 1950, Energy resources 

of the United States, Fourth World Power 

Conference, London. 

INT.-DUP. SEC., WASH., D.C. ShU