GEOLOGICAL SURVEY CIRCULAR 94 

Deeember 1950 

COAL RESOURCES OF THE UNITED STATES 

A progress report, November 1, 1950 

By 

Paul Averitt and Louise R Berryhill 
UNITED STATES DEPARTMENT OF THE INTERIOR 

Oscar L. Chapman, Secretary 

GEOLOGICAL SURVEY 

W. E. Wrather, Director 

Washington, D. C. 

Free on a lication to the GeololricalSUl"Yl .Washi ton..25 --L---------
CONTENTS 

Introduction ............................................................................... " . Preparation of coal-reserve estimates ......................................................... . 

Rank of coal ................................................. .' .......................... . Original, remaining, and recoverable reserves ............................................ . Percentage of coal recovered in mining ......... · .......................................... . Procedures used in estimating reserves .................................................. . Thickness of beds ................................................................. . Areal extent of beds ................................................................ . Overburden ........................................................................ . Measured, indicated, and inferred reserves .......................................... . Weight of coal ............................... ~ ..................................... . Distribution of coal in the United States ........................................................ . 

illinois ................................................................................. . Indiana ................................................................................. . Kansas ................................................................................. . Maryland ............................................................................... . Michigan ............................................................................... . Missouri. .............................................................................. . Montana ................................................................................ . New Mexico .............................................................. , ............. . North Carolina ......................................................................... . Ohio ................................................................................... . Pennsylvania .........................................................................•.. West Virginia .......................................................................... . Wyoming ............................................................................... . Other states ............................................................................. . Alaska ................................................................................. . Coking-coal reserves ............. ~ ......................................................... . World coal reserves ....................................... · ................................. . Relation of coal in the United States to other sources of energy ................................... . Life expectancy of United States fuel reserves ............. ~ ........................... : .. · ..... . 

Conclusions ................................................................................ . References ................................................................................. . 

ILLUSTRATIONS 

Paqe 

1 

3 

3 

3 

8 

8 

9 

9 

9 

11 

11 

11 

12 

12 

12 

13 

14 

15 

15 

16 

18 

19 

19 

21 

21 

28 

23 

23 

25 

27 

29 

32 

32 

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

2. 

3. 

4. 

5. 

Table 1. 

2. 

3. 

4. 

5. 

Remaining coal reserves of the United States, January 1, 1950........................ 2 

Heat value of coal of different ranks comtJared to proximate analyses. . . . . . . . . . . . . . . . . . . 6 

Remaining coal reserves of the ·united States, January 1, 1950, by states accordirg to 

tonnage and heat value ............................. , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 

Percentage of total energy supplied by mineral fuels and water power, 1900-1949........ 28 

TABLES 

Coal reserves of the United States, January 1, 1950, by rank......................... 4 

Coal reserves of the United States, January 1, 1950, by states .................. I • • • • • 5 

Estimated original coal reserves of the world by continents and principal 

coal-producing counties. o 0 I I I o I o I I I o 0 o o 0 0 0 0 I I o o o I o o o o o I 0 I I I 0 0 0 0 0 0 0 0 0 0 o o I I I 0 0 0 0 0 26 

Total ultimately recoverable mineral-fuel reserves of the United States, January 1, 

1950 .•..... 0 •••••••••••••• 0 ••••••••••••••••••• 0 •••••••••••••••••••••••••••••• '30 

Total assured recoverable mineral-fuel reserves of the United States, January 1, 

1950. I I I o 0 0 0 0 0 0 0 o o o o o I 0 0 0 0 o o I 0 o 0 o 0 0 0 o 0 0 o 0 0 0 0 0 o 0 0 o 0 0 0 0 o 0 0 0 0 o 0 0 o o 0 0 0 0 0 0 o 0 0 o 0 o 0 I 31 
-

~ 

-

~ 

Anthracite 

and semionthrocite 

Low-volatile 

bituminous cool 

Medium- and high-volatile 

bituminous cool 

Subbituminous cool 

§gg~~~ Lignite 

,-:7-

'-- ' ,/ "' --""\.. wq- I ;---~-t.--r',..--,--

' 

• .,...._.~, : • r I . ., ·, ., • I I I ' A• '- I , ',/ I ', ~ • ___ , cP ~ r 

.. "" .. ';;, ~ . . \ .:. ~ \ \ 

• ,: • ' I. . ' , 

.~ •. - ) I I ~ • I I ---( I ..-----\ 

) 

t\~ ____ , 

. ~-r . . I I \' r--'\.. '~ '~ ""! 

,, 0 200 400 600 Miles :?"';..-

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

By 

Paul Averitt and Louiae R. Berryhill 

INTROD.UCTION 

Interest in the quantity and quality of the coal 

reserves of the United State:;; has increased greatly 

since the end of World War II, principally because of 

the growing realization that the ultimate reserves of 

petroleum and natural gas, although largely undefined, 

still. have finite limits. With the greatly increased use 

of petroleum and natural gas, it has become further 

apparent that the reserves of these two fuels, whatever 

their ultimate limits may prove to be, are being consumed 

at a rate far surpassing that anticipated a few years ago. 

At some time in the future, therefore, the contribution 

of coal to the total production of energy in this country 

must inevitably be enlarged to include some of the needs 

now served by petroleum and natural gas. 

Although coal-bearing rocks cover 14 percent of 

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

enormous reserves, it is equally apparent that reserves 

of coal also have limits. In the extensively mined 

sections in the East it is already increasingly difficult 

to locate new areas containing thick beds of high-rank 

and high-quality coal to replace areas that have been 

mined out. Furthermore, a considerable part of the 

total reserves of the United States consists of coal of 

lignite and subbituminous ranks and coal contained in 

thin beds that can be mined only with great difficulty 

and expense. At the present time, therefore, the 

depletion of reserves of high-rank and high-quality· 

coal, particularly the Eastern coal that is suitable for 

the manufacture of metallurgical coke, is a more serious problem than the percentage depletion of the total 

coal reserves. 

Recog:p.izing the need for more detailed estimates 

of ·coal reserves than those that have been available in 

the past, the U. S. Geological Survey is now preparing 

a reappraisal of the coal reserves of the United States 

'in which primary emphasis is placed on the amounts 

of coal in separate categories according to rank,thickness of coal, and thickness of overburden. Many of the 

state geological surveys in coal-producing areas are 

also preparing new appraisals of coal reserves. The 

increasing volume of geologic data available on the 

occurrence of coal and the detailed and careful methods 

now employed in calculating reserves should ultimately 

provide a more reliable estimate for the coal reserves 

of the United States than has been obtainable previously, 

although much additional work remains to be done. 

According to the information currently available, 

the total coal reserves of the United States remaining 

in the ground on January 1, 1950, are 2, 425,566 million 

tons, which are divided by rank as follows: 

Remaining coal reserves of the United States, January 1, 1950 

Estimated total Estimated recoverable reserves, 

reserves remain- January 1, 1950, assuming 50 percent 

Rank ing in the ground, recovery 

January 1, 1950 (In millions of (In quadrillions 

(In millions of short tons) short tons) of B. t. u.) 

Bituminous coal ..... 1, 232,635 616,318 16,024 

Subbituminous coal .. 467,700 233,850 4,443 

Lignite ............. 711,451 355,725 4,767 

Anthracite and 

semianthracite ... 13,780 6,890 175 

I 

Total ..... 2,425,566 1, 212,783 25,409 

1 
I Anthracite 

ond semionthrocite 

A 

I 

I 

I 

s 

Bituminous cool 

Sobbl-o <OOI . rn 00 bUUoo lono 

IJ Lignite 

L 

L.lt.C. 

Figure 2. - Remaining cool reserves of the United States, January I, 1950 
These totals, which are somewhat less than the 

previous, widely quoted estimates of M. R. Campbell 

of the U. S. Geological Survey, are based on new appraisals of coal reserves in Michigan, Montana, New 

Mexico, North Carolina, and Wyoming, prepared since 

1948 by the U. S. Geological Survey; on appraisals of 

reserves in illinois, Kansas, Missouri, Pennsylvania, 

and West Virginia, prepared by the geological surveys 

of those States;and on the older estimates of Campbell 

for the remaining states. Both for past and for estimated future losses in mining, the more realistic 

figure of 50 percent has been used, instead of the 

figure of 34. 7 percent derived in 1923 by the U. S. 

Bureau of Mines for the U. S. Coal Commission 

(Rice and Paul, '1923) and used in preparing most of 

of the previous estimates of the U. S. Geological 

Survey. · 

PREPARATION OF COAL-RESERVE ESTIMATES 

All 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. 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. Progress toward full knowledge of 

the coal reserves of the United States depends, therefore, upon an active 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. 

The U. S. Geological Survey is also preparing 

summary appraisals of coal reserves by states. All 

the published information on the thickness and extent 

of coal beds, together with unpublished data contained 

in the files of the U. S. Geological Survey and State 

surveys and data from mining and drilling companies, 

is used as a basis for these summary estimates. The 

reserve figures are classified according to rank and 

thickness of coal, thickness of overburden, and abundance 

of reliable information concerning the presence of coal 

at a distance from mines, drill holes, or outcrops. The· 

reserve estimates for Michigan, Montana, New Mexico, 

North Carolina, and Wyoming have been presented previously in separate detailed publications.. These studies, 

together with available reserve estimates published by 

the State geological surveys of illinois, Kansas, Missouri, 

Pennsylvania, and West Virginia, provide the basis for 

the provisional tables included in this circular. (See 

table_s 1 and 2 and fig. 2. ) For other states, where 

little or no detailed summary work on coal reserves 

has been carried on, the estimates used in the new 

provisional tables are those of M. R. · Campbell as 

reprinted by Hendricks and others. (Hendricks, 

1939; Buch, Hendricks, and Toenges, 1947). It should 

be noted that the Campbell estimates were made on a 

more generous basis than the recent estimates and, 

although appearing in the same tables, are not directly 

comparable. To alter these figures arbitrarily by 

some purely mathematical method for use in this 

progress report would be unnecessarily confusing, 

however, particularly in view of the fact that the 

revision of certain of these state estimates is now in 

progress by the Geological Survey. 

3 

Estimates ·of coal reserves based on information 

currently available are inevitably only provisional 

estimates and are subject to change as mapping, prospecting, and development are continued. 

At the present stage of knowledge, therefore, 

estimates of coal reserves must be based on many 

assumptions as to the thickness, extent, and correlation of the coal beds and other pertinent factors. 

These factors are described in the following paragraphs 

as a basis for explaining the points of similarity and 

difference between the estimates of reserves in different 

states presented in the accompanying tables. 

RANK OF COAL 

Coal is classified by rank according to percentage 

of fixed carbon and B. t. u. content. As shown in figure 3, 

the percentage of fixed carbon and the B. t. u. content, 

except in anthracite, increase from the lowest to the 

highest rank of coal as the percentages of volatile 

matter and moisture decrease. The reduction of 

volatile matter and moisture and the accompanying 

increase in fixed carbon took place progressively 

during the 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 accumulated 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. Locally, 

deformation of the coal-bearing sediments by movements 

of the earth's crust also aided in the process of coalification. The ranks of coal--lignite, subbituminous 

coal, bituminous coal, and anthracite--represiO!nt 

successive stages in the formation of 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 on page 7, 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 ~ and in tables 1 and 2. 

ORIGINAL, REMAINING, AND RECOVERABlE ~mVES 

The coal reserves shown in tables 1 and 2 are 

further classified as original reserves, remaining 

reserves, and recoverable reserves. Original reserves 

are reserves of coal 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. Remaining 

reserves are reserves in the ground as of the date · 

of appraisal and are obtained by subtracting past 

production and losses f'i-om original reserves. Recoverable reserves are reserves of coal in the ground 

as of the date of appraisal that can actually be produced 

in the future and are obtained by subtracting estimated 

future losses in mining from the 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 
State 

Table 1.--Coal reserves of the United States, January 1, 1950, by rank 

(In thousands of short tons) 

Reserves depleted to 

January 1, 1950 

Produced and 

Estimated lost in mining, Remaining original Produced ];/ assuming past reserves, reserves losses equal January 1, 1950 

production 

BITUMINOUS COAL 

Recoverable 

reserves, 

January l, 1950 

assuming 

50-percent 

recovery 

Alabama •••••••••• 67,570,000 821,590 1,6h3,180 65,926,820 32,963,410 Arkansas • • • • • • • • • 1,396,000 82,785 165;570 . 1,230,430 615,215 

Colorado ••••••••• 213,071,000 357,719 715,~38 212,355,562 1o6,177,781 

Georgia • • • • • • • • •• . 933,000 11,533 23,066 m,9Jl&. lJ5l.L,967 Illinois ••••••••• 171,905,000 3,131,997 6,263,99~ 165, ,006 82,826,503 

Indiana •••••••••• 53,051,000 984,137 1,968,27~ 51, ,726 2i,541,363 Iowa ••••••••••••• 29,160,000 ~3,162 686,3~ 28,473,676 1 ,2)6,838 

Kansas ••••••••••• £/ 17,574,000 Jl 9,800 Jl 19,600 17,554,400 ,777,200 

Kentucky ••••••••• 123,327,000 1,951,803 3,903,606 119,423,39~ 59,711,697 

Maryland ••••••••• 8,043,000 I./ 2$9 ,9~~30 519,886 7,523,11~ 3,761,557 Michigan ••••••••• 296,900 ~ 46 2/ 11,000 219,900 109,950 Missouri ••••••••• 79,362,016 · 257,7 7 5

6

15,574 78,846,4h2 39,423,221 

Montana •••••••••• 2,362,610 31,491 2,982 2,299,628 · 1,149,614 

New Mexico ••••••• 10,947,700 88,169 176,378 10,771,322 5,385,661 North Carolina ••• .110,462 1,054 2,108 108,)54 5~,177 

Ohio ••••••••~•••• 86,497,000 1,694,259 3,388,518 8),108,462 41,55[,?41 Oklahoma ••••••••• 54,951,000 158,846 317,692 54,633,308 27,316,6$4 

Pennsylvania ••••• 75,093,459 7,416,9$6 14,~)3,912 60,259,5~ 30,129,774 

Tennessee •••••••• 25,665,000 324,718 049,436 25,015,5 12,507,782 

Texas •••••••••••• 8,000,000 10,7o6 21,412 7 1 978,58 3,989,294 

Utah ••••••••••••• 88,184,000 195,833 391,666 87,792,3Jh 43,896,167 Virginia ••••••••• 21,149,000 538,867 1,077,774 20,071,226 10,035,613 

Washington ••••••• 11,413,000 123,8~ 247•608 11,165,392 5,582,696 

West Virginia •••• 116,618,447 4,979,385 9,958,770 106,659,677 53,329,838 

Wyoming •••••••••• 13,234,950 230,272 460,544 12,774,4o6 6,)87,29) Other states §I •• 820,000 4,956 9,9i2 810,088 405,044 ~------~--~------~~-4~----~~--+-------~---+----~~~~ 

Total •••••• 1,280,735,544 24,057,852 48,100,224 1,232,635,320 616,317,660 

SUBBITUMINOUS COAL· 

Colorado ••••••••• 104,175,000 107,5o6 215,012 103,959.986 ll,979.96i Montana •••••••••• 132,151,o60 124,~ ~,088 131,901,972 5.9l0,9 New Mexico ••••••• 50,801,200 32,22 ·i52 50,736,748 25,3 8,3l~ Utah •••••••••••• • 5,156,000 2,832 5, 64 5,150,336 2,575,1 Washington ••••••• 52,41J2,ooo 19,100 le.,200 52,40~,800 26,201,900 Wyomingy ••••••••• 108,318,900 132,103 2 ,2o6 108,05 ,69~ 54,027,3~7 Other states 1/ .• 15,500,000 3,832 7,664 15,492,33 7.746,1 8 

Total •••••• 468,544,160 422,143 844,286 467,699,874 233,849.937 

LIGNITE 

Arkansas ••••••••• 90,000 0 0 90,000 i5,000 Montana •••••••••• 87,533,270 1,21i 2,426 87,5~,8~ 43.7 5,422 North Dakota ••••• 6oo,ooo,ooo 67,85 135,712 599,8 ,2 299.932,144 South Dakota ••••• 1,020,000 921 1,8rz 1,01 ,158 ~,,079 Texas •••••••••••• 23,000,000 51,341 102,6 2 22,897,318 11, ,659 Wyoming Y ••••••• --- --- --- --- --- Other states 3/ •• 49.963 1 2 49.961 24,981 

Total •••••• 711,693,233 121,332 242,664 711,450,569 355,725,285 

ANTHRACITE AND SEMIANTHRACITE 

Arkansas ••••••••• 230,000 9,109 18,218 211,782 1~,891 Colorado ••••••••• 100,000 5,921 11,8~ 88,158 ,073 New Mexico ••••••• 5,700 1,092 2,1 ~ 3,516 1,75 Pennsylvania ••••• 22,805,000 4,916,oo6 9,832,01 12,972,388 6,486,~9% Virginia ••••••••• 500,000 9.592 19,184 480, 16 2lj.o,ij.o Washington ••••••• 23,000 0 0 23,000 11,500 

Total •••••• 23,663,700 4.941.720 9,883,440 13,780,260 6,890,130 

Total, 

all ranks • 2,484,636,637 29,543,047 59,070,614 2,425,566,023 1,212,783,012 

!/ Production, 1800 through 1885, from The first century and a quarter of American coal 

induatry, by H. N. Eavenson, privately printed, Pittsburgh, 1942; production, 1886 through 1949, 

from u. s. Bureau of Mines Minerals Yearbooks, unless otherwise indicated. ~ Remaining reserves, Januar1 1, 1946. 11 Production, January 1, 1946; to January 1, 1950. ~ Michigan Geological Survey Division, as cited in U. s. Geological Survey Circular 77, Po 56, 1950o 

5/ Past losses assumed to be 40 percent of coal originally in the ground. 2/. Includes Arizona, California, Idaho, and Oregon. 7/ Includes Arizona, Calif'ornia, and Oregon.· ~ Small reserves and production of' lignite included under subbituminous coal. 2/ Includes Calif'ornia and Louisiana. 
c:J1 

State Bituminous 

coal 

Alabama ••••••••• 67,570,000 

Arkansas •••••••• 1,396,000 

Colorado •••••••• 213,071,000 

Georgia ••••••••• 933,000 

Illinois •••••••• 171,905,000 

Indiana ••••••••• 53,051,000 

Iowa •••••••••••• 29,160,000 

Kansas •••••••••• y 17,574,000 Kentucky •• ~ ••••• 123,327,000 

Maryland •••••••• 8,043,000 

Michigan •••••••• 266,900 Missouri •••••••• 79.3 2,016 

Montana ••••••••• 2,362,610 

New Mexico •••••• 10,947.700 North Carolina •• .110,462 

North Dakota •••• Ohio •••••••••••• 86,497,000 

Oklahoma •• •••••• 5~.951,000 Pennsylvania •••• 7 ,093.459 South Dakota •••• --- Tennessee ••••••• 25,665,000 

Texas ••••••••••• 8,000,000 

Utah •••••••••••• 88,184,000 

Virginia •••••••• 21,149,000 

Washington •••••• 11,413,000 

West Virginia ••• 116,61e,447 

Wyoming ••••••••• 13,234,950 

Other states •••• 11 820,000 

Total ••••• 1;280,735,544 

Table 2.--Coal reserves of the United States, January 1, 1950, by states (In thousands of short tons) 

Estimated original reserves Reserves depleted to January 1, 1950 

Produced and 

Produced 11 lost in mining, Subbituminous Lignite Anthracite Total assuming past coal and losses equal semianthraci te production 

--- --- --- 67,570,000 821,590 1,6~3,180 90,000 230,000 1,716,000 91,89~ 1 3,788 

104,175,000 --- 100,000 317,346,000 471,14 942,262 --- --- --- 933,000 11,533 23,0 6 

--- --- --- 171,905,000 3,131,997 6,263,994 

--- --- --- 53,0$1,000 984,137 l,t8,274 --- --- --- 29,160,000 343,162 86,~24 --- -·- --- y 17,.574,000 ll 9,800 ll 19, 00 

--- --- --- 123,327,000 1,951,803 3,903,606 

--- --- --- 8,043,000 2.59.943 519,886 

--- --- --- 2t,900 1!1 46,2~0 il 77,000 

--- --- 79.3 2,016 257,7 7 515,57~ 132,151,060 87,533,270 --- 222,04,6,640 157,248 314,49 50,801,200 --- 5,700 61,754. 00 121,507 243,01~ --- --- --- 110,462 1,054 2,10 

--- 6oo,ooo,ooo --- 6oo,ooo,ooo 67,856 135.712 --- --- --- 86,497,000 1,69~,2~6 3,388,~18 

--- --- --- 54,A51,ooo 15 ,8 ~17, 92 --- --- 22,805,000 97. 98.459 12,332,9 2 24, 65,~2i --- 1,020,000 --- 1,020,000 921 1, 4 

--- --- --- 25,665,000 324,718 649.436 

23,000,000 --- 31,000,000 62,0~7 124,094 5,156,000 --- --- 93.l40,000 198,6 5 396.330 --- 500,000 21, 4.~,000 548,479 1,0~ ,~58 52,442,000 --- 23,000 63,87 ,000 lj.i.2,904 2 5, 08 

--- --- 116,618,~7 4.979,385 9.958, 770 ~108,318,900 

~ --- 121,553, 50 362,375 724,750 y 15,500,000 49.963 --- 16,369.963 8,799 17,578 

468,544,160 711,693~233 23,663,700 2,484,636,637 29,543,047 59,070,614 

Recoverable 

reserves, 

Remaining January 1, 1950, 

reserves, assuming January 1, 1950 50-percent 

recovery 

65,926,820 32,96l,410 1,532,212 76 ,106 

316,403,708 1$8,201,854 

609,93~ ~54.967 165, 41,00 82, 20,503 

51,082,626 25,541,363 29,4,7~. 76 1~,2.36,838 

17.,5 ,400 ,777,200 

119, 23,394 59.711,697 

7,523,114 3,761,557 

216,900 109,950 

78,34 ,442 39.~23,221 221,732,~ 110, 66,222 

61,511,5 30,755.793 

108,354 54,177 

599,86%,298 299.932,144 8~,10 ,482 41,55~,241 5 ,633,308 2l·~l ,65~ 73,232,535 3 ' 16,26 1,018,158 • 509,079 

25,015,56~ 12,507,782 

30,875.60 15,437.953 

92,942, 70 46.47~,335 20,552,042 10,27 ,021 

63,592,192 31,796,096 

106,659,677 53,329,838 

120,1329,100 60,41~,550 16,352,385 8,17 ,193 

2,425,566,023 1,212,783,012 

1886 

11 Production, 1800 through 1885, from The first century and a quarter of American coal industry, by H. N. Eavenson, privately printed, 1942; production, through 1949, from u. s. Bureau of Mines Minerals Yearbooks, unless otherwise indicated. 

~ Remaining reserves, January 1, 1946. 

Production, January 1, 1946, to January 1, 1950. 

Michigan Geological Survey Division, as cited in u. S. Geological Survey Circular 77, p. 56, 1950. 

Past losses assumed to be 40 percent of coal originally in the ground. ~ Small reserves of lignite included under subbituminous coal. 

71 Includes Arizona, California, Idaho, and Orego.n. ]V Includes Arizona, California, and Oregon. ~ Includes California and Louisiana. 
B. t.u. 

14,000 

10,000 

8,000 

6,000 

4,000 

2,000 

0 

Percent 

100 

80 

60 

40 

20 

0 

17:.------ r;7; 

/ ~ / ~ 

B 0 N 

Figure 3.- Heat value of coal of different ronks compared to proximate analyses. 

Upper diagram: Comparative heat value of typical samples of the several ranks of coal, computed on 

samples as received, on the ash-free basis. Lower diagram: Variation in the fixed ·carbon, volatile matter, and 

moisture of samples used in upper diagram, computed on samples as received, on the ash-free basis. 

6 
CLASSIFICATION OF COALS BY RANK." 

Legend: F.C. -Fixed Carbon. V.M.- Volatile Matter. Btu. - British thermal units. 

Class Group 

i 

1. Meta-anthracite ..............•.. 

2. Anthracite ...................•.. 

I. Anthracitic 

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

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 B . asts 

Dry F .c .. 98 per cent or more (Dry V.M., 2 per ce.nt or less) 

Dry F .C., 92 per cent or more and less than 98 per cent 

(Dry V.M., 8 percent 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) 

DryF.C., 78percentor.more and less tlian 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 tlian 78 per cent 

(Dry V.M., 31 per cent or less and more than 22 per cent) 

Dry F .c., less than 69 per ceni1 (Dry V.M., more than 31 per cent); and moistc Btu., 

14,()()C11 or more 

.Moistc Btu., 13,000 or more and less than 14,()()()8 

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

Moist Btu., 11,000 or more and less than 13,()()()8 

Moist Btu., 9500 or more and 

less than 11,()()C11 

Moist Btu., 8300 or more and 

less than 95()08 

Moist Btu., less than 8300 

Moist Btu., less than 8300 

Requisite Physical Properties 

N onagglomerating b 

Either agglomerating or nonweath~ring/ 

Both weathering and 

nonagglom_erating 

Consolidated 

Unconsolidated 

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-vola.tile 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 the-:-e may be noncaking varieties in each group of the bituminous class. • 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. 

7 
change with new mapping and exploration, is essentially 

a constant, needing no date nor explanation to make it 

understandable. From this estimate the figures 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. 

The only instance in which coal reserves can be 

calculated successfully without reference to original 

reserves is in virtually mined-out areas where remaining reserves are small and clearly defined. -In 

rn,ost coal areas in the United States, however, the 

remaining reserves still closely approximate the 

original reserves. This is particularly true in the 

West, where relatively little mining has been done. 

PERCENTAGE OF COAL RECOVERED IN MINING 

For calculating remaining and recoverable 

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 a comparison of 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 mining operations provide,in general, 

the only indication of the relative tonnages of coal that 

are recovered and lost in mining. 

The percentage of the total coal recovered in mining 

varies to a considerable extent, depending upon such 

factors as the structure of the coal beds and the methods 

used in mining. In calculating remaining and recoveral:lle 

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. Most studies of recoverability 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 recoveral>ility in larger areas include 

consideration of coal that is left in barrier pillars, in 

restricted areas around oil and gas wells, under towns, 

raib;oads, 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, Ill., for example, 

have shown a recovery of less than 50 percent of the 

coal originally present in the No. 6 bect in that county. 

A similar study by Flint (1949) has indicated that the 

recovery of coal in Perry County, Ohio, betweeri 1838 

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 Frank Pardee, Mining Engineer, 

8 

Michigan Geological Survey Division, and Louis 

Gabrick, Mine Inspector, Michigan Department of 

Labor (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 ped.'; , 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, · Pa. , 

as determined by Moyer {Hickok and Moyer, 1940). 

The weighted average recovery of bituminous coal in 

Cambria County, Pa., was determined by Dowd and 

others (1950) to be 48. 77 percent. 

As the results of these recently completed studies 

seem to be in accord, the estimated Temaining 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 generally include only 

the output of the larger mines, the total 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 complete data 

were available for the amounts of coal mined and lost 

in mining. 

PROCEDURES USED IN CALCULATING COAL RESERVES 

Estimates of. coal reserves, like those of :other 

mineral resources, are based on a series of assumptions 

in addition to the facts available from geologic observations, 

mining, and drilling. No uniform method .has been 

adopted for calculating coal reserves, and estimates of 

the tonnage of coal within individual areas tend to vary 

greatly, depending upon the assumptions and procedures 

used in preparing the estimates. An estimate of coal 

reserves has meaning, therefore, only when consider.ed 

in relation to the procedure followed in obtaining it_. 

For practical purposes, two cut-off points are 

required 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. To date, however, no opinion 

is generally accepted as to what figures represent the 

practical limits to be used for the thickness of coal 
beds and of overburden. 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 

conditions. A more inclusive estimate, on the other 

hand, may consider thinner, mor~ impure, and more 

deeply buried coal as recoverable by improved methods 

when more easily mined deposits have been exhausted. 

Other standards, in addition to those involving 

thickness of coal beds and of overburden, are employed 

in calculating coal-reserve estimates. The weight or 

specific gravity of the coal is determL."led or assumed, 

and the method of determining the extent of coal underground at a distance from an outcrop, mine, or drill 

hole is s.elected. Again, these standards vary with 

individual estimates, and the tonnages of coal in the 

estimates vary accordingly. 

The U. S. Geological Survey, in order to produce 

uniformity of thinking and procedure on the part of 

Survey coal geologists, has adopted a set of procedures 

to be used in the calculation of coal reserves. Estimates 

of coal reserves thus obtained can easily be combined in 

county, state, and nr>.tional totals of comparable value. 

These procedures, which were prepared jointly 

by members of the Geological Survey and the Bureau 

of Mines and include recommendations of the National 

Bituminous Coal Advisory Council, are discussed in 

the following paragraphs. 

THICKNESS OF BEllS 

In areas where coal beds are oi varymg thicknesses, the average thickness of each bed is determined 

for use in calculations of reserves. No standard procedure 

for determining such thickness is in use, but generally 

an average thickness or weighted average thickness is 

obtained from the observed thicknesses of the coal bed 

at various locations within the area. 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 is obtained by multiplying the average of the measurements of the thickness 

of the coal bed by ( 1 • Y), in which S is the sum of all 

measurements and SD is the sum of the numbers obtained 

by subtracting from the average each measurement 

below it or subtracting the average from each measurement 

above it. 

The modulus of irregularity was originally adopted 

by the U. S. Geological Survey as a mechanism in 

establishing the value of coal lands, (Smith, HH3) 

but it is no longer used for this purpose. As described 

in U. S. Geological Survey Bulletin 537, it was devised 

as a safeguard for the buyer of coal lands in areas where 

the coal beds vary 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 the appraisal 

of coal reserves. 

9 

According to the procedures of the U. S. Geological Survey, coal reserves are calculated and 

reported by beds in categories of thickness as follows: 

Anthracite, semianthracite, and bituminous coal 

More than 42 inches 

28 to 42 inches 

14 to 28 inches 

Subbituminous coal and lignite 

More than 10 feet 

5 to 10 feet 

2! to 5 feet 

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 figu.res, which are weighted according to the 

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 iuch 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 

parting3 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. 

AREAL EXTENT OF BEDS 

The areal extent of coal beds included in U. S. 

Geological Survey reserve estimates may be determined 

in several ways. Where the continuity. of the bed is 

well known from maps of the outcrop, rriine 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-h~ 

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 e~tend only 1 mile beyond the 

limits of the mine workings. An isolated drill hole 

too far removed to be incorporated 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. 

OVERBURDEN 

Wherever possible, reserve data are reported 

by the U. S. Geological Survey in three classes, 

according to thickness of overburden, as follows: 
Billions of tons 

Quadrillions of B. t. u. 

North Dakota 

Colorado 

Montana 

Illinois 

Wyoming 

Kentucky 

West Virginia 

. Utah 

Ohio 

Missouri 

Pennsylvania 

Alabama 

Washington 

New Mexico 

Oklahoma 

Indiana 

Texas 

Iowa 

Tennessee 

Virginia 

Kansas 

Maryland 

Arkansas 

South Dakota 

Georgia 

Michigan 

North Carolina 

Other states ll 

0 

0 

100 300 

7,800 

--

r1'1//m 

E::::::::::J 

-

400 

10,400 

500 

13,000 

Bituminous coal 

Subbituminous coal 

Lignite 

Anthracite and 

sem i(:mthraclte 

Figure 4 .. - Remaining coat reserves of the United States, January I, 1950, 

by states according to tonnage and heat value 

[Upper bar for each state shows coal reserves by tons; 

lower bar shows cool reserves by B. t. u.l 

!I Includes Arizona, California, Idaho, Louisana, and Oregon. 

10 

600 

15,600 
0 to 1, 000 feet 

1, 000 to 2, 000 feet 

2, 000 to 3, 000 feet 

MEASURED, INDICATED, AND INFERRF.D RESERVES 

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 coal is coal for which tonnage is 

compu:eJ. from dimensions revealed in outcrops, 

trenches, mine workings, and 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 coal is coal for which tonnage is computed 

partly from specific measurements and partly from projection of visible d:ita 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 1i miles apart for beds of known geologic 

continuity. 

Inferred coal is coal for which quantitative 

estimates are based largely on broad knowledge of the 

geologic character of the bed or region and for which 

there are few, if any, measurements. 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. 

WEIGHT OF COAL 

Where precise data are not available, the following values are assigned as the weight of coal in all 

U. S. Geological Survey calculations of coal reserves: Tons per acre-foot 

Anthracite and semianthracite ------- 2, 666 

Bituminous coal--------------------- 1, 800 

Subbituminous coal------------------ 1, 770 

Lignite------------------... ---------- 1, 750 

DISTRIBUTION OF COAL IN THE UNITED STATES 

Coal deposits are widely distributed throughout 

the United States, as shown in figure 1, which also 

shows the very unequal distribution of coal according 

to rank. Only 30 percent of the total coal reserves of 

the United States occur east of the Mississippi River, 

yet this area contains 60 percent of the total reserves 

of bituminous coal and anthracite. The coal-bearing 

states west of the Mississippi River contain 70 percent 

of the total reserves of the Nation, but most of the 

coal is of lignite, subbi}uminous, or high-volatile 

bituminous rank. ' 

This variation in :¢ank of coal according to 

geographic distribution~is principally the result of 

differences in age. In he East, and in Kansas, Iowa, 

Oklahoma, and Arkans s, the coal is of Pennsylvanian 

I 11 

age; in the West, on the other hand, the coal is of 

Cretaceous or Tertiary age. The younger Western 

coal attains high rank only locally, in relatively small 

areas,where it has been deformed and.altered by the 

forces that accompanied mountain building and intrusions 

of igneous rock. 

The best grades of coke are manufactured from 

medium-volatile bituminous coal or from blends of 

high-volatile and low-volatile bituminous coal. Most 

of the deposits of coal suitable for the manufacture 

of metallurgical coke, therefore, are east of the 

Mississippi River, in areas where mining has been 

carried on extensively. Some areas in the West, of 

which the most important are the Raton Mesa region, 

Colorado-New Mexico, the Sunnyside field, Utah, 

and the Cre~ted Butte field, Colorado, contain deposits 

of coal that are used in coke production. These areas 

stand out prominently in plans for the industrial 

development of the West. 

The far larger reserves of lignite and subbituminous 

coal in the West have only local value at present, though 

it seems· certain that they will have greater usefulness 

in the future. Coal of these ranks tends to crumble 

during transportation and to ignite by spontaneous 

combustion if stored without special precautions for 

too long a period. It also has a lower hea:t value than 

other coal. On the other hand, the low-rank coal is 

well suited for the synthetic production of gas and 

liquid fuels, and, as this coal lies under very light 

overburden in many parts of the West, it is also well 

suited for strip-mining, which is being carried on 

locally in the West with great efficiency. 

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 B. t. u. 

basis. Such a comparison is presented in figure 4, 

which shows the remaining reserves in each state 

as of January 1, 1950, on both a tonnage and a B. t. u. 

basis. The B. t. u. content of typical coal in each rank 

and subdivision is given in figure 3. 

As somewhat differem. 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 further facilitated by a consideration 

of the methods by which each estimate was obtained. 

Even in the recent appraisals of coal reserves in 

Michigan, Montana, New Mexico, North Carolina, 

and, Wyoming, which were prepared by the U. S. 

Geological Survey according to the basic outline already discussed, minor differences in procedures 

were necessary becauS'e of differences in the occurrence 

of the coal and in the amount of information available. 

Even greater differences in assumptions and procedure 

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." 

Although the methods employed in preparing 

appraisals of reserves in a few states are markedly 

different from those used in the majority of states, 

no attempt has been made in any of the tables or 

illustrations used throughout this report to introduce 

arbitrary mathematical adjustment in the published 

figures. It was felt that the differences represent 

studied decisions by the appraisers and are due 

probably to .differences in the occurrence of the coal, 

amount of information available for making an appraisal, 

and other local factors not susceptible to simple 

mathematical adjustment. The different methods 

employed have given results of somewhat different 

magnitude, however, and deserve careful consideration. 

IUJN01S 

The original reserves of coal in illinois, as 

estimated by Cady, ( 1946) totaled 171, 905, 000, 000 

tons, all of bituminous rank. Cady based his reserve 

figure for the most part upon a consideration of the 

previously published estimates of the coal reserves of 

various mining districts in illinois (Cady, 1915, 1916, 

1917, 1919, 1921; Culver, 1925; Kay, 1915; Kay and 

White, 1915), and also upon more recently acquired 

data about the coal beds in the State. (Cady, 1944, 

p. 44}. 

All coal beds averaging 2 feet or more in thickness were included in the estimate. In the calculation 

of the reserves a specific gravity of 1. 3, or a weight 

per acre-foot of 1, 770 tons, was assumed. 

Tables were prepared to show the distribution of 

the total coal reserves of illinois by counties and by 

mining districts. As most of the coal in illinois lies 

under a moderate overburden, no attempt was made 

to classify the reserves according to thickness of overburden, nor were attempts made to classify the reserves 

according to bed thickness or abundance of reliable 

information used in making the reserve estimate. 

INDIANA 

The estimated original reserves of coal in 

Indiana, according to Campbell, totaled 53,051,000,000 

tons, all of bituminous rank. This figure is based 

upon detailed estimates by Ashley (1898 and 1908). 

In the 1898 report Ashley estimated the original 

coal reserves of Indiana to be 39,618,240,000 tons 

but later, in 1908, increased the figure to 

46,864,000,000 tons. The original publication shows 

the total coal reserves of Indiana classified by coal 

beds and by cou.-·1ties; the supplementary publication 

shows reserves by counties only. In both estimates, 

Ashley included all coal beds 1 foot or more in thickness and assumed a specific gravity of 1. 15, or a weight of 1, 560 tons per acre-foot, for the coal. In 

the actual calculations of reserves, however,· Ashley 

rounded off the figure for the weight of the coal and 

used a factor of 1, 500. 

Ashley estimated the recoverable coal reserves 

of Indiana as of January 1, 1908, to be 13,621, 600,000 

12 

tons. In obtaining this figure, he included all beds 2! · 

feet or more in thickness and assumed a recovery of 

60 percent for the coal. On this basis, the recoverable 

reserves of the State in beds 2! feet or more thick 

are 29. 2 percent of the original reserves. 

Campbell accepted Ashley's 1908 estimate for 

the total coal reserves of Indiana but recalculated 

the estimate to the selected specific gravity of 1. 3,or 

a weight of 1; 770 tons per acre-foot, for the coal. 

In making the recalculation Campbell apparently 

compared Ashley's stated figure of 1, 560 tons per acrefoot to his own preferred figure of 1, 770 tons per acrefoot and thereby obtained a total of 53,051,000,000 tons. 

KANSAS 

The estimated potential bituminous coal reserves 

of Kansas remaining in the ground on January 1, 1946, 

totaled 17, 574, 000,000 tons, of which 949,323,000 tons 

is classified as proved reserves. The proved reserves 

include .60, 000,000 tons of coal which can be produced 

by strip-mining methods under present conditions. These 

estimates were made in 1945 and 1946 by Abernathy, 

Jewett, and Schoewe (1947) on the basis of geologic 

data collected by the State Geological Survey of Kansas 

and drilling records obtained from coal-mining companies·. 

Tables were prepared to show the distribution of proved 

and potential reserves by co~ties and by coal beds. 

In calculating the proved reserves, with the exception of that part classified as strippable coal, the 

following table was used to indicate the minimum thick-· 

ness of coal considered minable at various depths: 

Maximum depth to coal 

(In feet) 

Minimum thickness of co"'l 

(In inches) 

100 w 

150 18 

200 22 

600 32 

1,200 36 

The minimum thickness of coal beds included in proved 

strippable reserves and in potential reserves was 10 

inches. Strippable coal considered in the reserve estimate 

had a maximum depth of 60 feet or an overburden of not 

more than 35 cubic yards per ton of coal. The maximum 

overburden used in determining proved coal reserves was 

1 200 feet and the maximum overburden for potential 

r~serves ~as 3, 000 feet, the maximum generally used in 

estimating coal reserves in the United States.· 

The proved reserves of coal, as defined in the 

report of the State Geological Survey of Kansas, wet'~ those 

lying within a reasonable distance from a. known occurrence 

of coal based on the experience of the coal industry and on geofogical observations of the continuity of coal beds 

in Kansas. The limits of potential reserves, on the 

other hand, were based on the general regional stratigraphic continuity of the coal-bearing rocks. In calculating the area underlain by proved reserves, a 

measured thickness of coal at an outcrop, at a drill 

hole, or in a mine was considered to prove the 

presence of coal of the same thickness under 1 square 

mile. Two or more known occurrences of the same 

coal bed ·within a distance of 4 miles along the line of 

strike were considered to prove the bed to be continuous 

between these points. In calculating the potential 
reserves, a measured thickness of coal at an outcrop, at a drill hole, or in a mine indicated the 

oresence of coal of the same thickness under 400 

square miles. The areas of both classes of coal 

reserves were greatly reduced in many places because of additional information .about the location of 

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

In computing the tonnages of coal in the Kansas 

report, a specific gravity of 1. 1, or a weight per 

acre-foot of 1, 500 tons, was assumed. This is a 

very low specific gravity for average bituminous coal 

in the ground, which more generally is assumed to 

have a specific gravity of 1. 3'2, or a weiqht of 1, 800 

tons per acre-foot. Had the average weight of the 

coal in Kansas been assumed to be 1, 800 tons per 

acre-foot, the estimate of reserves remaining in the 

ground on January 1, 1946, would have been increased 

20 per cent, to 1, 139, 187,600 tons for the proved 

reserves and 21, 086, 800, 000 tons for potential reserves. The more conservative figures, based on a 

weight of 1, 500 tons per acre-foot, are preferred by 

the members of the Kansas Geological Survey, however, and these figures are used in tables l and 2. 

MARYLAND 

The original reserves of coal in Maryland, all 

of bituminous rank, totaled 8, 043,000,000 tons as 

estimated by Campbell in 1928. The coal-bearing 

rocks _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. According to Campbell, the original reserves 

of coal in each of these basins were as follows: 

Campbell included in his estimate coal 14 inches 

or more thick lying under as much as 3; 000 feet of 

overburden. He assumed a specific gravity for the 

coal of 1. 3 or a weight of 1, 770 tons per acre-foot 

In estimating the coal reserves of Maryland, Campbell 

had only a small amount of data available on the thickness and continuity of the beds, and, in the tight of 

more recent mapping and exploratory drilling, his 

estimate now appears to be considerably larger than 

·the actual amount of coal in the State that can be 

mined under present economic conditions .. Campbell's 

estimate serves, however, to show the approximate 

relative distribution of reserves in the five basins. 

In 1949, the results of a cooperative program 

of drilling and geologic investigations by the U. S. 

Bureau of Mines and the U. S. Geological Survey in 

the Georg~s Creek basin and the northern part of 

the Upper Potomac basin in Maryland were published 

by the Bureau of Mines. (Toenges and others, 1949} 

This study showed that on January 1, 1947, remaining 

measured and indicated reserves of 399,214,000 tons 

were present in beds 18 inches or more thick lying 

below the Pittsburgh bed. Of this total, 56, 118,000 tons 

was in beds 18 to 24 inches thick, 220,059,000 tons in 

beds 24 to 36 inches thick, and 123,037,000 tons in 

beds more than 36 inches thick. Because of the depth 

at which much of the coal· occurs in the Georges Creek 

and Upper-Potomac basins, however, few of the beds· 

under 36 inches thick can be mined profitably. 

The Georges Creek basin and the northern part 

of the Upper Potomac basin covered by the cooperative 

study include approximately 60 percent of the coal 

reserves in Maryland according to Campbell's figures 

on the relative distribution of reserves in the five 

basins. On this basis, the total remaining measured 

and indicated reserves of the State as of January 1, 1947~ 

in beds 18 inches or more thick were about 665 million ' 

tons. 

Original coal reserves of Maryland by basins as estimated by M. R. Campbell 

Original reserves 

(In short tons) Percent of total 

Georges Creek basin ......... 4,373,000,000 50 

Upper Potomac basin ......•.. 1,664,000,000 20 

Castleman basin ............. 229,000,000 5 

Upper Youghiogheny basin .... 1,035,000,000 15 

Lower Youghiogheny basin .... 742,000,000 10 

Total ........ 8,043,000,000 100 

13 
MICmGAN 

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 estimate 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 

by Pardee and Gabrick (see page 8 . ) 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, · o'nl.y those areas having adequate test-hole 

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 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 

The measured reserves were also divided into 

14 

the followinc] categories according to the· thickness 

of overburden: 

50 to 100 feet 

100 to 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 contained in beds 14 inches or more thick, however, 

and are 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 coal was defined as coal blocked 

out by closely spaced drilling, and the outer limit of a 

block of measured coal was drawn within a few hundred 

feet of the outermost points of positive information. 

This conservative assumption was necessary to define 

measured coal in Michigan because of the known lack 

of continuity of the beds. Indicated coal was defined 

as coal for which tonnage estimates were based 

prim~ily 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 

coal was defined as coal 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 coal 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 have a specific gravity of 1. 32, or a weight of 

1, 800 tons per acre-foot. 

The accompanying table shows the estimated 

remaining coal reserves of Michigan as of January . 

1, 1950, classified ac;.cording to thickness of bed, 

thickness of overburden, and abundance of reliable 

information. 
Estimated remaining coal reserves of Michigan, January 1, 1950 · (In thousands of short tons) 

Thickness 

Overburden ofbed 

Measured 

reserves Total 

Bituminous coal 

(14 to 28 in. 1,180 --- --- --- 50 to (28 to 42 in. 11 2,630 --- --- --- 100ft. (42 in.-t-: ------ --- --- --- Total !I 3,810 --- --- (14 to 28 in. 23,800 --·- --- --- 100 to (28 to 42 in. 64,100 --- --- --- 200ft. (42 in.+ 10.160 --- --- --- Total, '98_,_960 --- --- --- (14 to 28 in. 3,920 --- --- --- 200 to (28 to 42 iri. y 14,430' --- --- --- 300ft. (42 in.+ 4.650 --- --- ~otal W' G;:i, 000 --- --- ---

Total .............. J 124,870 1 y 28,980 1 _y 66,050 1 219, ooo 

1/ Includes 30 with overburden varying from 22 to 26 feet. ~/ Includes 3, 010 with overburden ranging from 300 to 366 feet. 

'!! Estimate not cl8$sified by thickness of bed or amount of overburden. 

MISSOURI 

The original coal reserves of Missouri as estimated by Hinds (1913) totaled 79,362,016,000 tons, 

all of bituminous rank. In Hinds' report the reserves are classified by counties, and, for certain counties, 

additional tables are presented to show reserves by 

coal beds or by townships. 

Hinds included in his estimate all coal beds 14 

inches or more in thickness and assumed a specific 

qravity of 1. 32, or a weight of 1, 800 tons per acre- foot, for the coal. No attempt was made to classify reserves according to thickness of bed or overburden. 

Hinds further estimated that the recoverable 

coal reserves of Missouri, assuming ideal market 

and labor conditions, will not equal more than 60 

percent of the original reserves, or 47, 702, 108,400 

tons. 

II>NTANA 

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 87, 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 geoloqic 

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

publications of the Montana State Bureau of Mines 

and Geology, and similar sources were analyzed for 

data necessary for the calculation of the reserve 

15 

figures. Tables were prepared to show the classification 

of reserves by counties. 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 ot the beds. The 

omitted areas are. concentrated, in general, in the northaastern,. lignite-bearing part of the State, where the coalbearing 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 2i feet 

for subbituminous coal and lignite. For the purpose of 

classifying the reserves, separate estimates were prepared for coal·in the followi~g thickness ranqes: 

Bituminous coal 

More than 36 inches 

24 to 36 inches 

14 to 24 inches 

Subbituminous coal and lignite 

More" than 10 feet 

5 to 10 feet 

2t to 5 feet 

The maximum overburden for coal included in 

the estimate was 2, 000 feet, but as about 75 percent of 

the total coal was less than 1, 000 feet below the surface, no classification of the reserves was made on the basis 

of thickness of overburden. 

The assumed areal extent of each coal bed was 
Estimated original coal reserves of Montana 

(In thousands of short tons) 

Overburden Thickness Measured and Inferred Unclassified. Total 

of bed indicated reserves reserves 

reserves 

Bituminous 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 ft. (36 in.+ 1,036,330 . 388,990 --- 1 425 320 

Total 1,662,800 699,810 --- 2,362,610 

Subbituminous coal 

! 

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

0 to (5 to 10ft. 15,485,620 9,245,940 --- 24,731,560 

2,000 ft. (10ft.+ 26,370,190 15,974,920 --- 42,3~5, 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 

0 to (5 to 10ft. 6,613,070 

2, 000 ft. (10ft.+ 2,566,030 

(Unclassified --- Total 14,055,270 

Total, 

all ranks .............. 62,965,990 

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 also coal under roads, railroads, and the like. All known areas of burned coal, 

however, were excluded. 

Two classes of coal based on the quantity of 

reliable information available for making reserve 

estimates were established, as follows: 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. 

On the basis of about 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, or a weight of 1, 800 tons per acre-foot, was 

selested 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. 

16 

10,177,750 --- 15,053,920 

13,135,880 --- 19,748,950 

435,000 --- 3,001,030 

--- 49,729,370 49,729,370 

23,748,630 49,729,370 _87' 533, 270 

. 51, 995,450 107,085,500 222,046,940 

The accompanying table shows the estimated original 

coal reserves of Montana classified according to rank, 

thickness of bed, and abundance of reliable information. 

NEW.MEXJCO 

The original coal reserves of New Mexico 

totaled 61, 754, 600, 000 tons, as 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 of the total coal reserves of New 

Mexico, which is classified to show reserves by 

counties and coal fields, 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 

the estimate was 2! fee~ 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: 

Subbituminous coal 

More than 10 feet 

5 to 10 feet 

2! to 5 feet 
Estima.ted oriqinal coal reserves of New Mexico 

(In thousands of short tons) 

Overburden Thickness Measured Indica.ted Inferred Reserves Total 

of bed reserves reserves reserves inferred 

by zones 

Bituminous coal 

(14 in.+ --- ---- --- 2,377,900 2,377,900 

0 to (14 to 28 in. 72,800 359,100 334,300 --- 766,200 

1, 000 ft. (28 to 42 in. 151,900 334,200 27,100 --- 513,200 

(42 in.+ 429~500 611,600 360, 100 --- 1,401,200 

Total 654,200 1,304,900 721,b00 2,377,900 b,Ob8,b00 

(14 in.+ --- --- __ ... 1,763,600 1,763,600 

1, ooo·to (14 to 28 in. 400 7,100 694,300 --- 701,800 

2,000 ft. (28 to 42 in. --- 39,400 355,400 --- 394,800 

(42 in.+ --- 69,40Q 715,300 --- 784~700 

Total 400 115,900 1,765,000 1,7~3,600 3,644,900 

(14 in.+ --- --- --- 1,838,900 1,838,900 

2,000 to (14. to 28 in. --- 2,600 25,300 --- 27,900 

3,00? ft. (28 to 42 in. --- 600 --- --- 60o· 

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

Total --- 3,200 402,200 1,838,900 2,244,300 

Total ••.••...•.•••• 654,600 1,424,000 2,888,700 5,980,400 10,947,700 

Subbituminous coal 

(2! ft.+ --- --- --- 16,363,500 16,363,500 

Oto (2! to 5 ft. 446,800 1, 021,300 1,227,000 --- 2,695,100 

1, 000 ft. (5 to 10ft. 228,100 348,400 997,.600 --- 1,574,100 

(10ft.+ . 151, 600 160,900 --- --- 312.500 

Total 826,500 1,530,600 2,224,600 16,363.500 20,945,200 

(2! ft.+ --- --- --- 13,154,700 13,154,700 

1,000 to (2! to 5 ft. --- 60,900 165,300 --- 226,200 

2,000 ft. (5 to 10 ft. --- 39,100 743,800 --- 782,900 

(10ft.+ --- 121,300 537,800 --- 659,100 

Total · --- 221,300 1,446,900 13,154,700 14,822,900 

(2! ft.+ --- --- --- 13,288,000" 13,288,000 

2,000 to (2t to 5 ft. --- 3,600 502,000 --- 505,600 

3,000 ft. (5 to 10ft. --- 12, 100 448,600 --- 460,700 

(10ft.+ --- --- 778,800 --- 778_J800 

Total --- 15,700 1,729,400 13,288,000 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 ft. (28 to 42 in. 1,400 300 --- --- 1,700 

(42 in.+ 500 100 --- ./--- 60()-

Total 2,800 2,900 --- _,__ 5,700 

Total •••.•.•••••..• 2,800 2,900 ~,709 

Total, 

all ranks . ; ........ . 1,483,900 a, 194,500 18,289, ooo 148,786,600 161,754, 60o 

17 
Bituminous coal and anthracite 

More than 42 mcfies 

28 to 42 inches 

14 to 28 inches 

In areas where information about thickness of 

coal beds was reasonably adequate because of drilling and mining development, isopach lines were drawn 

on the coal beds and 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 

measurements, it was possible only to determine 

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 and 

:-eliability 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 the coal beds and the· topography and 

structure of the larger coal-bearing areas, would 

not fit into any of the thr~e 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 Sari· Juan Basin or the Raton 

Mesa field. The coal zones were therefore subjected 

to further examination as zones instead of individual 

beds, and the additional reserves thus derived were 

included in a category ter:med "Inferred by ~one." 

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 overburden thickness were 

established. 

In calculating the reserves of New Mexico, the 

bituqainous coal was assumed to have a specific 

gravity of 1. 32, or a weight of 1, 800 tons per acrefoot; the subbituminous coal was assumed to have a specific gravity of 1. 3, or a weight of 1, 770 tons 

18 

per acre-foot; and ttle anthracite was assumed to 

have a specific gravity of 1. 47, or a w~ight of 

2, 000 tons per acre-foot. 

The estimated original reserves of New Mexico, 

classified according to rank of coal, thicknes~ of bed, 

amount of overburden, and abundance of reliable information, are shown in the accompanying table. 

NOR111 CAROUNA 

All the coal of commercial quality in :r...rorth Carolina 

is containeid in the Deep River field in Chatham, Lee, 

and Moore Counties. The original reserves of this 

field, as estimated by Reinemund (1949} totaled 

110,462,000 tons . The reserve estimate includes 

·only coal in the main bench of the ·Cumnock coal bed 

and in the Gulf coal bed; it does not 1ncluoe 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 

ccal, the estimate includes small amounts of semianthracite and anthracite where the coal bas been 

altered locally by igneous intrusions. 

The reserves were divided into three classes 

according to the thickness of the coal, and separate 

estimates were prepareq for reserves in beds 14 to 

24 inches thick, beds 24 to 36 inches thick, and beds 

more than 36 inches thick. 

The reserves were also 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 inclu~ed in the 

estimate. · 

A further classification of the reserve figures 

was made according to the relative abundance of 

reli8.ble information regarding the continuity and thickness of the coal beds. Reserves were classed as measured 

where the tonnages were computed from thi · knesses 

shown in closely spaced drill holes, mine workings, 

and outcrops; as indicated where the tonnages were 

computed partly from s~ific 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 s:Pecific 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 accompanyinj table shows the estimated 

original coal reserves of North Carolina classified 

acco_rding to thickness of bed, amount of overburden, 

and relative abundance of reliable information. 
Estimated oriqinal coal reserves of North Carolina 

(In thousands of short tons) 

Overburden Thickness 

of bed 

Measured 

reserves 

Total 

Bituminous coal 

(14 to 24 in. 8,423 

Oto (24'to 36 in. 8,027 

2,000 ft. (36 in.+ 15.635 

Total 32,085 

(14 to 24 in. --- 2,000 to (24 to 36 in. 1,063 

3,000 ft. (36 in.+ --- Total 1,063 

Total ..••....... · .•• 33,148 

omo 

According to combined estimates of Clark (1929) 

and Flint (1949), the oriqinal coal reserves of Ohio 

totaled 86, 497,000,000 tons, all of bituminous rank. 

In 1929 Clark estimated the oriqinal reserves of Ohio 

to be 87,638,000, OOOtons, of which 2, 141,000,000 

tons was estimated to be in Perry County. On the 

basis of new geologic work in 1949 Flint recalculated 

the reserves of Perry County and estimated the original reserves to be only 1, 000,000,000 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 surfac~ 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 eqwil 

to the distance that the bed was known to extend above 

drainS.ge. Where the coal bed was believed to be 

persistent along its outcrop and r~asonably constant 

in thickriess~ 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 toe texts of the State reports. 

In the calculation of the reserves a specific 

19 

18,612 23, 561· 50,596 

17,943 --- 25,970 

3,851 - 19,486 

40,406 2;:$,561 96,052 

--- --- --- 13,347 --- 14,410 

--- --- --- .13,347 --- 14,410 

53,753 1 23,561 1 110,462 

gravity of 1. 32, or a weight of 1, 800 tons per acrefoot, 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 from his estimate, because 

detailed mapping showed that m this county these beds 

generally· are less than a foot thick or are completely 

missing. In calculating the reserves, Flint assumed 

the coal to have a specific gravity of 1. 32, or a weight 

of 1, 800 tons per acre-foot. 

Of the total 1, 000,000, 000 tons of coal estimated 

to have been originally present in Perry County, 

208,000,000 tons have been mined out or lost in mining. 

The remaining reserves as of January 1, 1949, there~ 

fore total 792, 000, 000 tons. 

Flint conducted a study of the recovery of coal 

in mining operations in Perry County from 1838 to 

1948 which showed that during this period only 43 

percent of the coal was recovered. This figure was 

based upon measurements of mined-out areas in the 

county as compared to production stat~stics. On this 

basis, the recoverable reserves of coal in Perry 

County total 340,000,000 tons. 

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' classi- . 

fied 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 assumf!d 

specific gravity of 1. 1, or a weight of 1, 50Q tons per 

acre-foot, for the coal. 1 This weight is very low for 

bituminous coal in the ground, however., and a more 

accurate, though conservative, figure can be obtained 

by a 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 ~ns. · 

PENNSYLvANIA · 

~e 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. Geoloqic;U Survey and the 

Pennsylvania Geologic and Topographic Survey, and 

from drill records, mine maps, and personal interyiews 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 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 the counties in 

Pennsylvania with the exception of Clarion and 

Jefferson. A. specific gravity of 1. 34, or a weight 

of 1, 820 tons per acre-foot, 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 very conservative figure for the coal reserves of Pennsylvania. 

Had a specific gravity of 1. 34 been used in the· 

calculations for all the counties, the estimated 

bituminous coal reserves of Pennsylvania would have 

::,een increased by 8 percent to a total of 80,545, 185,000 ~ons.-

Several additional estimates of the coal reserves 

af small areas in Pennsylvania have been calculated 

:lnQ can be used as a partial check on the Reese and 

Sfsler estimate for the entire State. These estimates 

are di.l?cussed in the following paragraphs. 

The coal reserves of two adjoining quadrangles, 

Punxsutawney and Curwensville, were estimated by 

S. H. Ashley (1928 and 1940). As Reese and Sisler 

used counties, townships, and coal beds as a basis 

for their estimate, Ashley's complete estimate for· 

two quadrangles cannot be compared with the estimate 

by Reese and Sisler. It is possible, however, to 

compare the two estimates of coal r.eserves 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, 347,800,000 tons, 

whereas Ashley estimated that the original coal 

reserves totaled 2, 785, 375,000 tons. Ashley's 

estimate, therefore, represents an increase of 

nearly 18 percent over the estimate of Reese and 

Sisler. 

In calculating the reserves of the Curwensville 

quadrangle, Ashley included only coal having an 

average net thickness of at least 18 iQ.ches. 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 coal 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 

20 

. ··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 a 

specific gravity of 1. 32, or a we-ight of 1, 800 tons 

per acre-foot, for the coal. 

The coal reserves of the Smicksburg quadrangle 

were estimated by M. N. Shaffner (1948), 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 o{ 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 fortnula results in a figure for 

the thic)mess 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 

reserves of Fayette County, Pa., totaled 7, 570,000,000 

tons (Hickok and Moyer, 1940). For the same area 

Reese and Sif!ler estimated that the oriqinal 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 ~bowed the same 

characteristics and for which an averaqe section could 

be determined. The area ~der lain by coal was obtained 

by planimeter measurements. Minable thicknesses of 

the averaqe sections were used in all calculations. The 

minable thickness· of a coal bed, as defined by Moyer, 

was the thickness of the coal after subtractinq partinqs, 

bone, and bony coal from the total thickness of the bed. 

Thin benches separated by a thick partinq from the 

principal bench of a coal bed were also excluded in 

considerinq minable thickness. No coal havinq an 

averaqe minable thickness of less than 28 inches was 

included in the estimate. Moyer assumed a s~cific 

gravity of 1. 37, or a weight of 1, 880 tons per acre-foot, 

for the coal in Fayette County. 

The original coal reserves in seven beds in 

Cambria County, Pa. , '-ere estimated by Dowd and 

others (1950) to total 2, 406, 887,000 tons. This fiqure 

represents the measured and ind.icated coal in beds at 

least 14 inches thick. Because the estimate does not 

include inferred reserves, it cannot be compared in 

its original form to the estimate of Reese and Sisler. 

All calculations for the Dowd estimate were based 

upon an assumed specific gravity of 1. 32, or a weight of 

1, 800 tons per acre-foot. 

In the strictest sense none of the reserves fiqures 
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 conservative q~ity 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, added 10 percent 

to the Reese and Sisler coal reserve figures for every 

county in Pennsylvania except Fayette County, for 

which he used the new estimate by Moyer. 

As has already been 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 

Pei)IlSylvania. 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 the other 

estimates included in this discussion. Considering 

the conservative nature of the Reese and Sisler estimate 

and the fact that no new complete estimate for the 

coal reserves of Pennsylvania is available, the continued use of their estimate without revision in the present 

tables seems justified at this time. 

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 reduced 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 

~eight of ~he coal included. Presumably, therefore, m compuhng 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; see also 

Lesley and others, 1895), who made the first care- ful estimate of the anthracite reserves. 

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 his figure for the anthracite re- serves, Smith used different values for the specific 

gravity of the coal in different localities within the 

anthracite fields, as determined by numerous tests. 

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 tons 

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-foot. Smith 

estimated that the original reserves of anthracite in 

Pennsylvania totaled 21,848,800,000 short tons. 

The several estimates of Pennsylvania anthracite reserves all were based upon assumed accordion folds 

in the coal-bearing rocks of the anthracite fields. 

21 

On the basis of recent work by Rothrock (1950), 

however, it now appears that some of these structures 

may be more correctly interpreted as thrust faults, in 

which case the reseryes of anthracite may be l"educed 

in future estimates. Smith's original estimate of 

21,848,800,000 short tons may therefore prove to be 

more accurate than the later estimates which have 

tended to increase the reserve figures. 

WEST VIRGINIA 

The original coal reserves of West Virginia 

totaled 116,618,446,894 tons, according· to an estim~e 

by Headlee and Nolting (1940). This figure represents 

the sum of the original coal reserves of each county as estimated in 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. 

All coal beds averaging 2 feet or more in thickness were 

in~uded in the estimate. A minimum cut-off point was established, however, and ·presumably no coal thinner 

than 18 inches was considered in calculating the reserves. 

Price and others (1938) state that approximately 

75,500,000,000 tons of coal in West Virginia is in beds 

that average 3 feet or more in thickness. The remainder 

of the original reserves, or approximately 41,000,000,000 

tons of coal, is in the thinner beds. 

In computing the reserves of West Virginia, the 

coal was assumed to have a sJ)ecific gravity of 1. 28, or 

a weight of 1, 742 tons per acre-foot. A specific gravity 

of 1. 28 is somewhat 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 acre-foot, which is more generally accepted as the average weight of typical 

bituminous coal in the ground, the West Virginia estimate 

would be increased 3 percent. 

WYOMING 

The original coal reserves of Wyoming, as 

estimated by Berryhill and others (Berryhill, Brown, 

Brown, ·and Taylor, 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 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 

(Berryhill, Brown, Burns, and Combo, 1950). 

The estimate, which shows the coal res~rves of 

Wyoming classified by counties and by townships, was 

based on published and unpublished reports of the U. S. 

Geological Survey, on pt}blications of the Geological 

Survey of Wyoming, and on records made available to 

the U. S. Geological Survey by mining companies, oil 

companies, and private individuals. 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. As more mapping and exploratory drilling 

programs are carried on.in the coal-bearing areas in 

Wyoming, therefore, the estimate of reserves should be 

substantially increased. . 
'The minimum thickness of coal included in the 

Wyoming reserve estimate was 14 inches for bituminous coal and 2! feet for subbituminous coal. The· 

reserves of different ranks of coal were classified 

according to the following thickness ranges: 

Bituminous coal 

More than 42 inches 

28 to 42 inches 

14 to 28 inches 

Subbituminous coal 

More than 10 feet 

5 to 10 feet 

2-! l't> 5 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 

::tS$umed area of coal occurrence, as was coal under 

~·oads and railroads. All known areas of burned coal, 

however, were. excluded. 

The coal reserves of Wyoming were classified 

in this estimate in the following ranges according to 

thickness of overburden: 

0 to 1, 000 feet 

1, ooo to 2, ooo feet 

2, 000 to 3, 000 feet 

The reserves were further divided, according to 

the relative abundan~e of reliable information on which 

the estimates were based, into the three 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 specific gravity 

of 1. 32, or a weight of 1, 800 tons per acre-foot, and the 

subbituminot.ls coal was assumed ,to have a specific 

gravity of 1. 3, or a weight of 1, 770 tons per acre-foot. 

The accompanying table 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 ft. 

1,000 to 

2, 000 ft. 

2, 000 to 

3, 000 ft. 

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 .............. 

(2f to 5 ft. 

0 to (5 to 10ft. 

1, 000 ft. (10ft.+ 

Total 

(2! to 5 ft: 

1, 000 to (5 to 10 ft. 

2, 000 ft. (10ft.+ 

Total 

(2! to 5 ft. 

2, 000 to (5 to 10ft. 

3, 000-ft. (10ft.+ 

Total 

Total ... ........... 

Total, 

both ranks .....•.•.. 

Indicated 

reserves 

Bituminous coal 

24,400 446,070 

149,610 680,760 

1, 512 910" 2,180,750 

1,686,920 3,307,580 

4,860 143,590 

21,840 332,310 

318,840 1,507,040 

345,540 1, 982_, 940 

--- 58~700 

--- 98,350 

30,140 1,043,580 

30, 140 1,200,630 

2,062,600 6,491,150 

Subbituminous coal 

7,890 6,503,920 

70,960 9,151,400 

1,473,670 15,561,830 

1,552,520 31,217,150 

--- 737,660 

5,070 673,090 

1. 780 363.600 

6,850 1, 774,350_ 

--- 281,540 

--- 266,210 

--- -171,830 

--- 719,580 

1,559,370 33,711,080 

3,621,970 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 

2,278,360 

4,681,200 

7,358,730 

i5,428,480 

35,148,700 

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 

4 287,120 

5,727,910 

424,510 

779,920 

2,793,480 

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 

108,318,900 

121,553,850 
OO'BER STA n::s ·• 

In this progress report of the U. S. Geological 

Survey's program for the reappraisal of the coal 

reserves of the United States, it has not been possible 

to include new appraisals for all: states. For states 

not previously discussed, therefore, the only estimates available are those prepared by Campbell in 

the years prior to 1928. These have been included 

in tables 1 and 2 for the sake of completeness. 

In calculating his estimates of original reserves, 

Campbell used the following minimum thicknesses for 

the different ranks of coal: · 

Bituminous coal and anthracite~--- 14 inches 

Subbituminous coal-------------- 2 feet 

Lignite------------------------- 3 feet 

Otherwise, he included in a single category 

all coal to. a depth 3, 000 feet below the surface. 

Campbell based his estimates on an assumed specific 

gravity of 1. 3, or a weight of 1, 770 tons per acrefoot, for coal of all ranks. 

Campbell's estimates of coal reserves were 

carefully prepared, but for many areas he had very 

little information with which to work, and in an attempt 

to provide a comprehensive estimate of all possible 

coal in the United States he made statistical allowance 

for the continuity of coal beds over large unmapped 

·areas and areas concealed by glaCial drift or younger 

rocks. In states where the coal beds have been 

demonstrated to be discontinuous the Campbell estimates are conspicuously high. In states where very 

little information on coal is available for certain areas, 

or where the coal-bearing rocks are concealed, the 

more rigid methods of calculating coal reserves now 

employed by the Geological Survey will also tend to 

reduce the Campbell estimates by excluding such areas from consideration. 

Although it is recognized that, in general, the 

Campbell estimates are high and are subject to revision, they are included in tables 1 and 2 as originally 

prepared. With an active program of work in progress · toward the revision of these estimates, arbitrary 

changes at the present time would not result in valid 

figures and would tend to be confusing. It is hoped 

that a complete, documented revision of the Campbell 

estimates can be completed in the near future. 

ALASU 

Coal is known to occur in substan~ 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 

appraisal of the total coal reserves in the Territory 

can be made at the present time. According to· an 

appraisal 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, Hendricks, and Toenges, 1947,' p. 235), of 

which 23,800,000,000 tons is bituminous coal; 

82,594,000,000 tons, subDituminous 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 

23 

of detailed "information. Access to transpbrtation 

facilities is the chief factor affecting coal-miriing 

development in Alaska, and the reserve figures 

presented in the accompanying table are· therefore 

classified by region and by accessibility to present railroads. 

By January 1, 1950, the total recorded production 

of coal in Alaska totaled 5~ 621., 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. 

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 proc;:esses. Coal of 

medium-volatile bituminous rank is best for use in 

coke production, but reserv_es 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 low-volatile coal is used in a blend with 

high-volatile coal that alone produces only an inferior 

coke. Poorly coking coal is sometimes improved by 

blending with s_uch noncoking ingredients as anthracite 

fines, petroleum coke, or low-temperature char. 

In ·addition to rank the ba?it plant constituents 

of a coal also seem to be important in determining 

the suitability of a coal for manufacturing coke, and 

such deleterious constituents as ash and sulfur must 

not be present in excessive quan~ities. 

Most of the reserves of high-rank and high-quality 

coal best suited for coke production are found in the 

East, principally in West Virginia, Pennsylvania, 

Kentucky, and Virginia. ln a few areas .in the West, 

principally in Colorado, Utah, New Mex1co, Oklahoma, 

and Arkansas, coal is produced that is satisfactory for 

the manufacture of coke when used in blends. The available information· about reserves of such coal in the West 

is summarized in another report (Berryhill and Averitt, 

in preparation). 

Because of the almost limitless possibilities of 

blending coals and other hydrocarbons in the manufactUJ!e 

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, grade, and sulfur content, conforming to ranges now regarded as acceptable for use in mak~ 

coke, and to report coal reserves in these categor.ies, 

but this has not as yet be,en done. 

· As low-volatile bituminous coal is_a blending 

agent that makes possible the use of vastly, larger r~- . serves of high-volatile bituminous coal for coke.pr6ductlon, 

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 shown in the following table, as estimated on 

the basis of information prepared by the Pennsylvania 

and West Virginia Geological Surveys and information 

presented by M. R. Campbell in aU. S. Geological 
Estimated original coal reserves of Alaska 

(In thousands of short tons) 

Within 40 

miles of Remote 

Accessible present from 

by present means of present 

Region means of transpor- means of 

transpor- tation but transportation not immedi- tation 

ately available 

Bituminous coal 

Arctic Ocean drainage •• --- --- 22,000,000 

Yukon and Kuskokwim 

drainage basins .!/ ... --- y --- .Pacific Ocean drainage and Alaska 

Peninsula 3/ •••••••• 450,000 . 1,350,000 --- -. 

Total •.•••.••.••. 450,000 1,350,000 22,000,000 

Subbituminous coal and liqnite 

Arctic Ocean draiitaqe •.• --- --- 60,000,000 

Yukon and Kuskokwim 

drainaqe basins ,!/. •• --- 400,000 --- Pacific Ocean drainaqe and Alaska 

Peninsula Y ......... 2,400,000 19,600,000 186,000 

Total •.•••.•••.•• 2,400,000 20,000,000 60,186,000 

Liqnite 

Southeastern Alaska •••• J 8,000 f. 

Anthracite . 

Pacific Ocean drainaqe and Alaska 

Peninsula 3/ •••••••• ---- 1,000,000 --- Total, all ranks ••• 2,858,000 22,350,000 82,186,000 

Total 

22,000,000 

---

1,800,000 

23,800,000 

60, -ooo, 000 

400,000 

22,186,000 

82,586,000 

8,000 

1,000,000 .. 

107,394,000 

Y Excludes areas south of the Tanana River tr.ibu~y to the Alaska Railroad 

and the Richardson Hiqhway. 

2/ Present, but quantity unknown. !/ Iricludes areas excluded in Yukon and Kuskokwim drainaqe l)asins. 

24 
Original low-volatile bituminous coal reserves of the United States 

Reserves 

(In thousands 

State of shor~ tons) 

West Virginia ........... 10,251,139 

Pennsylvania ........... 5,672,905 

Maryland .............. 4,021,500 

Oklahoma ............... 2,000,000 

Arkansas .............. 1,226,000 

Virginia ............... 400,000 

Other states ........... 934,000 

Total ........ 24,505,544 

Survey press release on the coal resources of the 

United States printed in 1928. 

The total coal reserves of some of the states 

shown in the table may no doubt be reduced by detailed mapping and more restricted methods of 

calculating reserves, and the reserves of low-volatile 

bituminous coal will be lowered accordingly. The 

proportion of low-volatile coal_reserves to total coal 

reserves can be expected to remain approximately 

the same, however, as both the figures just given 

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 

low-volatile bitumino'Q.s coal represent 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 coal, 

however, because of the desirable qualities of t~s 

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 coal was mined,of which only 

about 25 percent was used in manufacturing coke 

(Fieldner, 1950, pp. 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 of low-volatile coal, on the other 

hand, are rapidly being exhausted, and the remainin~ reserves 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 recoverable. With a more or less limited supply 

of low-volatile bituminous coal available, it is apparent tllil.t coking operations and ~etallur<]iCal processes 

rnust soon be adjusted to permit l!l~J.·ea..,mg use 0! 

lower -rank coal, of which lar_ger reserves still 

remain. 

WORLD COAL RESERVES 

Estimates of the coal reserves of the world 

by continents and principal producing countries, 

25 

Percent of Percent 

total reserves of total U. s. 

in state reserves 

8.8 - 5. 8 - 50.0 - 3. 6 - 71.5 - 1.8 - - -

..... 1.0 

as compiled by the Fourth World Power Conference 

(Brown, 1948), are shown in table 3. All figures in 

the table are in metric tons, the standard unit for 

measuring coal in most countries other than the United 

States. One metric ton. is equivalent to 1: 1 short tons. 

With 2, 254,027 million metric tons of coai, as 

currently appraised,the United States appears to have 

39. 9 percent of the total world reserves of 5, 651, 920 

million metric tons. By comparison, the entire North 

American continent appears to have 43. 2 percent of 

the total, and Asia, including European Russia, appears 

to have 40. 6 percent. 

Table 3 gives only a very generalized comparison 

of the reserves in the principal coal-producing countrieS 

of the world. Because of the various methods of calculating coal reserves, the different standards of 

thickness and depth adopted, and the different dates 

for which estimates were made for different countries, 

the individual figures shown in the table are comparable 

only to the extent that they show the general magnitude 

of reserves in each country. In particular, the revisions 

in recent years of methods of calculating coal reserves 

by some countries, together with continued adherence 

to older principles by others, means 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 regardless of quality, minability, or accessibility of the 

coal. 

Canada provides an example of the effect of revision of methods of coal-reserves calculation. Figures 

published in 1913 gave Canaqa original reserves of 

1, 360, 535 mitlion metric tons of coal (Twelfth International Geological Congress, 1913). Since that time, 

CanC)..dian methods have been revised, and, as a result, 

the reserves are now ~stimated as being 89,644 million metric tons (MacKay, 1947). The earlier estimate was made on general assumptions of continuity 

of coal beds based on few observations and inclluded 

statistical allowance for all possible coal to a minimum thickness of 1 foot reqardless of quality, minability, .. or accessibility. Present Canadian estimates 

include only known developed or explored coal beds 

which, for reasons of thickness, quality, and 

extraction costs, were considered economically 
Table 3. --Estimated original coal reserves of the world 

by continents and principal coal-producing countries 

Originql reserves Percent of Percent of 

Continent and country (In thou·sands of continent world 

metric tons) total total 

North America: 

United States 1/. : . .... 2,254,027,000 92.3 39.9 

Alaska 2/. ... ~ ........ 97,426,000 4.0 1.7 

Canada~ ............. 89,644,000 3.7 1.6 

Total ............. 2,441,097,000 100.0 43.2 

Asia: 

U. S. S. R. 3/ ........... 1,200,000,000 52.2 21.2 

China ... ~ ........... 1, 011,000,000 44.0 17.9 

India ................ 62, 143,000 2.7 1.1 

Japan ............ 16,218,000 . 74 . 28 

Others .!f ............ 7,563,000 . 36 . 12 

Total ............. 2,296,924,000 100.00 40.60 

Europe: 

Ge.rmany ............. 336,274,000 51.8 5.9 

United "Kingdom ......... 172,200,000 26.5 3. 1 

Poland ............ • "": 80,018,000 12.3 1.4 

Czechoslovakia ..... :. 18,950,000 2.9 . 35 

Portugal ............ · .. 10,236,000 1.6 . 19· 

Others.£!. ...•........ 31,134,000 4.9 . 56 

Total •............ 648,812,000 100.00 11. 50 

Africa: 

Union of South Africa .. 205,395,000 99.06 3.66 

Others §f. ............ 1,930,000 . 94 . 04 

Total ............. 207,325,000 100.00 3.70 

Australasia: 

'Australia . . . . . . ...... 53,100,000. 99.0 0.92 

Others V ............. 546,000 1.0 . 01 

Total ............ 53,646,000 100.0 0.93 

South America: 

Chile ............... 2, 116,000 51.4 0.036 

Others y ............. 2,000,000 48.6 . 034 .~ 

Total ............. 4, 116,"000 100.0 0.07 

World total ........ 5,651,920,000 . ..... 100.00 

]) Estimate of original reserves as shown in tables 1 and 2, converted 

to metric tons. 

~/ Estimate of original reserves as shown on page 24:, converted to 

metric tons. 

3/ Total for European Russia included with Asiatic Russia. !/ Includes Korea, Malaya, Manchuria, and Turkey. 

5/ Includes Austria, Belgium, Bulgaria, Denmark, Greece, Hungary, 

Italy, -The Netherlands, Norway, Rumania, Sweden, and Yugoslavia. 

~ Includes Algeria, Belgian Congo, French Morocco, Madagascar, 

Nigerta, and Tanganyika. 

7 I Includes New Zealand and New Caledonia. Y Includes Peru, Honduras, Colombia, and Brazil. 

26 
minable in 1946. Reserves for most other countries 

shown in table 3 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. 

RELATJON OF COAL IN THE UNITED STATES 

TO OTHER FORMS OF ENERGY 

Coal supplied 39. 3 percent of the energy produced 

for heat, light. and power in the United States in 1949. 

During the same year, petroleum and natural gas 

together contributed 53. 0 percent of the energy produced (U.S. Bureau of Mines, 1950). As shown in 

figure 5, the percentage of total energy supplied by 

coal has decreased steadily since 1900, when, prior 

to the general use of petroleum· and natural gas, 

90 percent of the energy used in the United States 

was supplied by coat Since that time, an increase in 

the use of the other two fuels, because of their availability and convenience, has been accompanied by a 

decrease in the percentage of energy produced by 

coal. · This trend is not expected to continue indefinitely. As the Nation's reserves of petroleum and 

natural gas diminish, coal will become increasingly 

important by filling many of the energy requirements 

now supplied by o~er fuels. Even assuming future 

competition from atomic sources, coal is an important factor in the national fuel economy and is likely 

to remain so for many years. 

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 630, 623,722 tons of coal was produced. 

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 579,385,820 tons of coal. 

The fact that the 1947 fig1.u-es for record production 

is so close to the 1918 figure seems to suggest that 

the maximum figure for annual coal production i_n the 

United States will be about 600,000,000 tons as long 

as petroleum and natural gas are available in quantity 

as sources of energy. No sharp rise from this established figure can be expected until coal is draW!! 

upon as a source of liquid as well as solid fuels. 

Estimates of coal reserves cannot readily be 

compared with estimates of petroleum and natural 

gas :reserves, because the 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 

beds maintain a fairly uniform thickness over relatively large areas. From geologic observations made 

at the outcrops of coal beds, in mines and prospect 

pits, and from evidence supplied by drilling operations, 

the total quantity of coal in the ground can be estimated 

with reasonable accuracy. In the same way, estimates 

of total reserves of bituminous sandstone and oil shale 

can be obtained because these substances also occur 

in stratified deposits of measurable thickness and 

lateral extent. 

27 

Liquid petroleum and natural gas, on the other 

hand, are mobile substances that move through 

minute openings in the rocks and accumulate only 

where geologic relations provide traps that prevent 

further migration. As a great variety of structurql 

and stratigraphic relations create such traps, the 

total number of traps 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. 

Only proved reserves, or reserves in developed areas, 

can be estimated with any certainty for petroleum and 

natural gas, and consequently the estimates must be 

changed annually to accord with new discoveries and 

with production. 

Despite the recognized difficulty of comparing 

reserve estimates for various types of mineral fuels, 

it is desirable, nevertheless, to indicate the relation 

of coal reserves to the total mineral-fuel reserves of 

the United States.- In order to show reserves of the 

several different fuels on a.s;.J)f:arly similar bases as 

possible, two separate tables (tables 4 and 5) are presented, e.ach representing a major point of view in 

regard to reserve estimates. 

Table 4 shows the total ultimately recoverable 

mineral-fuel reserves of the United States as of 

January 1, 1950. The coal reserve estimate of 

1, 212. 79 billion tons shown in this table was obtained 

from tables 1 and 2. It includes measured, indicated, 

and inferred reserves of coal in both thick and thin 

beds, under light and heavy overburden. 

Several attempts have been made to obtain 

comparable figures for petroleum and natural gas 

reserves. These attempts have been based on the 

assumption that the total volume of marine sedimentary 

rock 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 explored thus far. Although no special 

accuracy is claimed for figures derived by these methods, 

the estimates based on currently available data are in 

good agreement. Weeks (1948, p. 1094) estimated the 

original, potentially recoverable reserves of petroleul!l 

in the United States, excluding the continental shelves, 

to be 110 billion barrels, and Pratt (Fanning, 1950, · 

p. 151) estimated the amount to be 100 billion barrels. 

Using the same methods, Terry (Fanning, 1948, p. 149) 

ootimated the original, potentially recoverable, reserves 

of natural gas in the United States to be 400 trillion 

cubic feet. Considering the additional quantities of oil 

present in the continental shelves, and 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 

the figures are too small rather than too la:r;ge. They 

are, however, of the oraer of magnitude required for 

a proper comparison of oil and gas reserves with total 

coal reserves. 

The figures derived by Weeks, Pratt, and Terry 

are, of course, intended to represent total ultimately 

recoverable original reserves; that is to say, past 

production, present proved reserves, and assumed 

future discoveries. To make them comparable With 

~he figure for total ultimately recoverable coal reserves 

as of January 1, 1950, they must be reduced to allow 
Percent of 

total energy supplied 

100 

90 

80 

70 

J60 

50 

40 

30 

,...., 

-............ 20 

10 

············ 

0 iliwJ-Eolo!o 

~ 

······ ····· 

Bituminous 

~ 

\;_opt 

.. c:r 

. ·.. .. . . ... . 

. ~OCilto .• 

~ V\_ 

············ v" 

----- ·- ...... 

I 

'l. 

~ 1\ ligniten A. '- -.JI.. U' 

~\; v ~ h 

.···· ... .. \ .. , ... ·· o\e\.l~.~ •• •• 

. ··· . . 

.·· .. ·. .. . . pe '~ •••• ·· .··. ~-...... 

I Natura_!,--~ lJ ~ ~ 

r--.... - "-Water_ _,f.£.'!_'!;. i-,...... ___ 

----- 1900 1905 1910 1915 1920 1925 1930 1935 1940 1945 1950 

Figure 5.- Percentage of total energy supplied by mineral fuels and water power, 

1900 - 1949. (Data from Bureau of Mines Minerals Yearbooks.) 

28 
for production to January 1, 1950. The figure used 

in table 4 of 61. 07 billion barrels for ultimately 

recoverable petroleum reserves as of January l, 

1950, was obtained by subtracting the total recorded 

production of petroleum to January 1, 1950, from 

Pratt's estimate of 100 billion barrels. Similarly, 

the figure of 277. 64 trillion cubic feet for ultimately 

recoverable natural gas reserves as of January 1, 

1950, was obtained by subtracting the total recorded 

production of natural gas to January 1, 1950, from 

Terry's estimate of 400 trillion cubic feet. 

Table 5, which is prepared on a more conservative basis than table 4, shows what is here 

termed the total assured recoverable mineral-fuel 

reserves of the United States, as of January 1, 1950. 

The estimates of 28. 38 billion barrels of petroleum 

and 180. 38 trillion cubic feet of natural gas shown in 

table 5 represent proved reserves as currently 

appraised by the American Petroleum Institute and 

the American Gas Association (Oil and Gas Journal, 

1950). To correspond with these estimates, an 

estimate for coal reserves is included that is intended 

to represent only measured and indicated reserves of 

coal in beds 28 inches or more thick under less than 

2, 000 feet of overburden. . The figure of 363. 85 billion 

tons for coal reserves in this restricted category was 

derived from a consideration of the reserve estimates 

for Michigan, Montana, New Mexico, North Carolina, 

and Wyoming, for which the reserves of coal have been 

classified according to thickness of bed and over -

burden. On an average in these States, the measured 

and indicated reserves of coal in beds 28 inches or 

more thick under less than 2, 000 feet of overburden 

total roughly 30 percent of the total coal reserves. 

This percentage wl!'s therefore applied to the figure 

for total recoverable coal reserves of the United 

States shown in table 4 to obtain the estimate for 

assured coal reserves shown in table 5. A further 

study of the same five States indicates that approximately half the assured coal reserves, or 15 percent 

of the total coal reserves, can be regarded as meas -

ured reserves of coal in beds 28 inches or more thick 

under less than 2, 000 feet of overburden. 

According to tables 4 and 5, the reserves of 

coal in the United States, wh,en compared on a B. t. u. 

basis, represent 87. 43 percent of the total ultimately 

recoverable mineral-fuel reserves, or 83. 06 percent 

of the total assured recoverable mineral-fuel reserves. 

It is interesting to note that these two figures are so 

nearly the same. 

LIFE EXPECTANCY OF UNITED STATES FUEL'RESERVES 

Because of the many imponderable factors to 

be taken into consideration, it is impossible to 

e~timate the life expectancy of fuel reserves in the 

U~ted States with any degree of accuracy. Although 

the \considerable annual increase in the per -capita 

use of energy in this country may be readily observed, 

· it. is doubtful that the rate of increase in population 

and in tlie use of energy can be extrapolated with 

sufficient reliability, or far enough into the future 

to afford a sound basis for predicting life expectancy 

of fuel reserves. Moreover, the trend toward increased use of energy may be offset in part by the 

trend toward greater efficiency in the production and 

use of fuel, the large amount of petroleum available 

29 

on other continents for import into the United States, 

and the likelihood that new sources of fuel and power 

will be developed in the future .. 

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 

present relative increase in use of petroleum and 

natural gas, which ·is due to the present abundance 

and comparative economy of these convenient fuels, 

will, therefore, continue as long as new petroleum 

and natural gas fields are discovered in the United 

States and as long as imported supplies of petroleum 

are available in domestic mar:Kets. 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, long 

before petroleum and natural gas reserves in the 

United States are diminished, a gradual increase in 

the use of coal may be expected. 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. In all probability, only the future historian 

looking backward will be able to say when the return to 

more general use of coal began. Because the life expectancy of petroleum and natural 'Jas reserves will 

be greatly extended as the relative use of coal and 

other fuels is increased, and because of the possibility 

of additions to petroleum and natural gas.reserves not 

allowed for in this report, an estimate of the life expectancy of any of these fuels is subject to serious 

question. 

The life expectancy of coal reserves is influenced 

by several additional factors. At present only a small 

percentage of the total coal reserves in the United 

States can be said to be accurately measured or definitely indicated to be present in the ground. The 

remainder is merely inferred to be present from available information on the distribution and thickness of 

coal beds and coal-bearing rocks, and its true quantity 

remains to be verified. The interim appraisal of coal 

reserves included in this report is therefore subject 

to considerable modification. Furthermore, the recoverable reserves of coal are assumed in this report 

to be only half the total reserves in the ground. This 

factor is based on the past average experience in a 

number of mining districts. The recovery from a few 

efficiently run mines, however, is much higher, and it 

is probable that in the future the average recovery in 

mining will improve. Also, many thin beds, not now 

considered to be minable, may ultimately be included 

as recoverable reserves if underground gasification 

.techniques, now in the experimental stage, can be 

improved. 

The manner in which coal is used is per haps the 

largest indeterminable factor that enters into any 

consideration of the life expectancy of coal reserves. 

Viewing future uses of coal over a long period, it is 

apparent that with the slow return to coal, the uses at 

first will be the same as at present. As noted by 

Wrather and o·thers (1950), however, the United States 

is committing itself to a liquid- and gaseous-fuel 

economy, and ultimately coal will serve as one of the 

sources of these fuels in addition to filling the 
c.o 

0 

Table 4.-- Total ultimately recoverable mineral-fuel reserve.s. of the United States, January 1, 1950 

Type of mineral fuel 

Coal: 

Bituminous coal •••••••••••••oo 

Subbituminous coal •••••oooo•o• 

Lignite ••••••••••••••••••••••• 

Anthracite and semianthracite • 

Total coal, all ranks ••••••• 

Petroleum 

Bitumen from bituminous sandstone 

Ultimately recoverable reserves and average annual production 

(Coal in billions of short tons; 

petroleum, b.itumen from 

bituminous sandstone, and oil 

from oil shale in billions of 

barrels; and natural gas in 

trillions of cubic feet) 

Ultimately 

recoverable 

reserves, 

January 1, 1950 

y 

J! 

lV 

616.32 

233.85 

355.73 

6.89 

Average annual 

production, 

1940-50 

0.544 

.007 

.003 

.057 

Oil from oil shale •••• o •• o o o •••• I 21 

1,212.79 

61.07 ? 

1.25 

500.00 

277o64 ? 

0.611 

1.780 

Negligible 

Negligible 

Natural gas ••••••••• o •••••••• o •• I 2/ 4.710 

Ultimately recoverable reserves and average annual production 

(In quadrillions of B.t.u.) !/ 

Ultimately 

recoverable I Average annual 

reserves, production, 

January 1, 1950 1940-50 

16,024.32 14.14 

4,443.15 .13 

4,766.78 .04 

175.01 1.45 

25,409.26 15.76 

366.42 ? 10.68 

7.50 Negligible 

3,000.00 Negligible 

277.64 ? 4· 71 

Ratio of 

ultimately 

recoverable 

reserves, as currently 

appraised, 

to average 

annual 

production, 

1940-50 

------

------

------

1612 

34 ? 

------

------ 59 ? 

I 

I 

Percent of 

total 

ultimately 

recoverable 

mineral-fuel reserves on B.t.u. basis, 

January 1, 1950 

55.14 

15 .• 29 

16.40 

.6o 

87.43 

1.26 

.03 

I 

10.32 

·96 

1/ Reserves and production figures converted to B.t.u.· according to the following heat values: anthracite, 12,700 B.tou. per 

pound; bituminous coal, 13,000 B.t.u. per pound; subbituminous coal, 9,500 B.t.u. per pound; lignite, 6,700 B.t.u. p~r pound; petroleum, bitumen from bituminous sandstone, and oil from oil shale, 6,000,000 B.t.,l. per barrel; and natural gas, 1,000 B.tou. per cubic foot. 

y Tables 1 and 2, PP• 4 and 5. 

J! Recoverable reserves of petroleum remaining after subtracting petroleum production to January 1, 1950, from original petroleum reserves of lOO'billion barrels, as esti~ated by w. E. Pratt in Our oil resources, second edition, edited by L. M. Fanning, McGraw-Hill 

Book Company, New York, 1950. Figure does not include continental shelves. 

lV Fifty percent of estimated measured, indicated, and inferred reserves of bitumen from bituminous sandstone in deposits near Vernal and Sunnyside, Utah; Casmalia, Santa Cruz, Edna, Sisquac, Sulphur Mountain, and San Ardo, Calif.; and Uvalde, Tex. 

21 Fifty percent of reserves of oil in oil shale deposits having an average content of 15 barrels of oil per ton, as estimated 

by D. c. Duncan, u. s. Geological Survey. Personal communication. . 

2/ Recoverable reserves or nat~ral gas remaining after subtracting natural gas production to January 1, 1950, from original 

natural gas reserves of 400 trillion cubic feet, as estimated by L. F. Terry in Our oil resources, first edition, edited by L. M. 

Fanning, McGraw-Hill Book Company, New York, 19~5. Figure does not include continental shelves. 
"' ........ 

Table 5.--Total assured recoverable mineral-fuel reserves of the United States, January 1, 1950 

Assured recoverable reserves and average annual production Ratio of 

(Coal in billions of short tons; Assured recoverable reserves assured Percent of 

petroleum, bitumen from and average annual produotion recoverable total 

bituminous sandstone, and oil (In quadrillions of B.t.u.) !/ reserves, as assured 

Type of mineral fuel from oil shale in billions of currently recoverable 

barrels; and natural gas in appraised, mineral-fuel 

trillioQs of cubic feet) to average reserves 

Assured Assured annual on B.t.u. basis, 

recoverable Average annual recoverable Average annual production January 1, 1950 production, production, 1940-50 reserves, 1940-50 reserves, 1940-50 January l, 1950 Jan~ary 1, 1950 

Coal: 

Bituminous coal ••••••••••••••• y 184.90 0.544 4,807.40 14.14 ------- 52.38 

Subbituminous coal •••••••••••• y 70.16 .001 1,333.04 .13 ------ 14.53 

Lignite ••••••••••••••••••••••• y 106.72. .003 1,430.05 .04 ______ , 

15.58 

Anthracite and semianthracite • y 2.07 .057 52.58 1.45 ------ .57 

Total coal, all ranks ••••••• 363.85 o.611 7,623.07 15.76 484 8.).06 

Petroleum ••••••••••••••••••••••• .l.1ll 28.38 1.780 170.28 10.68 16 1.86 

Bitumen from bituminous sandstone 21 .65 Negligible 3.90 Negligible ------ ·04 

Oil from oil shale •••••••••••••• y 200.00 Negligible 1,200.00 Negligible ------ 13.08 

Natural gas ••••••••••••••••••••• v 180.38 4· 710' 180.38 4.71 38 1.96 

1/ Reserves and produc~ion figures converted to B.t.u. according to the following heat values: -anthracite, 12,700 B.t.u. per pound; bituminous coal, 13,000 B.t.u. per pound; subbituminous coal, 9,500 B.t.u. per pound; lignite, 6,700 B.t.u. per pound; petroleum, bitumen from bituminous sandstone, and oil from oil shale, 6,000,000 B.t.u. per barrel; and natural gas, 1,000 B.t.u. per cubic foot. 

£1 Thirty percent of reserves as shown in table 1, determined by a consideration of five states for which reserve estimates have 

been classified by t~ickness of bed and overburden. The estimate is intended to show reserves of measured and indicated coal in beds 

at least 28 inches thick under no more than 2,000 feet of overburden. 

Jl Includes 3.73 billion barrels of natural gas liquids • 

• ~Estimate by the ~erican Petroleum Institute, as reported in the Oil and Gas Journal, vol. 49, no. 45, pp. 56-57, March 16, 1950. 

S/ Fifty percent of measured and indicated reserves of bitumen from bituminous sandstone in deposits near Vernal and Sunnyside, Utah; ~asmalia, Santa Cruz, and Edna, Calif.; and Uvalde, Tex. 

2/ Sixty p$rcent of measured reserves of oil shale containing 15 barrels of oil per ton, as estimated by Carl Belser in Oil shale resources of Colorado, Utah, and Wyoming, American Institute of Mining and Metallurgical Engineers Technical Publication 2358, 1948. 

V Estimate by the American Gas Association, as reported in the Oil and Gas Journal, vol. 48, no. 45, pp. 56-57, March 16, 1950. 
re4.u.lrements for solid fuel. If such conversion of 

:!oal becomes general, the needs for coal will be 

enormous, for 50 percent of the potential energy in 

coal is lost in the conversion to liquid fuel. 

Although it is thus impossible to predict the 

life expectancy of the several mineral fuels, the 

ratios between the currently estimated recoverable 

reserves of each fuel and the present annual rates 

)f production provide figures that are somewhat 

more meaningful for comparative purposes than the 

reserve figures alone. As shown in table 4, the 

ultimately recoverable reserves of coal in the United 

States are 1, 612 times the average annual production 

during the period 1940 to 1950; the ultimately recoverable reserves of petroleum are 34 times the 

average annual production; and the ultimately recoverable reserves of natural gas are 59 times the 

average annual production. 

Table 5, which is identical in arrangement with 

table 4, but based more conservatively on appraisals 

of proved or definitely assured reserves, shows that 

the assured recoverable reserves of coal in the United 

States are 484 times the recent average annual production; the assured reserves of petroleum are 16 

times the average annual production; and the assured 

reserves of natural gas are 38 limes the average 

annual production. 

From a consideration of the probable trends in 

the use of these fuels it is apparent that their probable 

life expectancy is quite different from the simple ratios 

<Jf present production as compared to reserves. Petroleum and natural gas reserves certainly have a much 

longer life expectancy than the ratios indicate, and 

coal reserves, conversely, have a shorter life exoectancy. 

CONCLUSIONS 

As appraised in this interim report, the coal 

reserves of the United States remaining in the ground 

on January 1, 1950, total 2, 425, 566 million tons, half 

of which can be regarded as ultimately recoverable. 

This total is made up of a number of individual state 

estimates, some of which were prepared as long ago 

as 1908, others of which were prepared in 1949. 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 light 

'lnd heavy overburden. These older estimates are 

useful only for the purpose of comparing the total 

reserves of one state with another. The more recent 

estimates have been prepared on a more conservative 

basis· than the older estimates and tend to be considerably 

smaller. A reduction of the total reserve figure reported is therefore in prospect, though the reserves 

still will appear abundant. 

The newer state estimates prepared by the U. S. 

Geological Survey, five of which are presented in 

this report, provide additional data on coal reserves 

in individual counties and smalier geographic units 

and in categories for each rank of coal according to 

the thickness of the beds, their depth below the surface, and the abundance of reliable information on 

which the appraisals were made. The newer state 

estimates thus have considerable usefulness in planning for the development of the coal and the coalb....:.aring regions. 

32 

Extrapolating from the small amount of detailed 

coal reserve data now available, it appears that 

roughly 15 percent of the total estimated reserves 

given in tables 1 and 2 can be regarded as measured 

reserves in beds 28 inches or more thick under less 

than 2, 000 feet of overburden; that an additional 15 

percent can be regarded as indicated reserves within 

the same limits of thickness and depth below the 

surface; and that the remaining 70 percent is inferred 

reserves, reserves i:q thin beds, or 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. These percentages 

are at best only rough approximations bas~d on msufficient data and are subject to change as new work is 

completed. Nevertheless, they serve to indicate the 

present state of knowledge of the NationJs coal reserves 

and· point to the need for additional geologic mapping, 

exploration, and appraisal. 

On a B. t. u. basis, the total ultimately recoverable reserves of coal as appraised on January 1, 1950, 

represent 87 percent of the total ultimately recover 

able fuel resources of the United States. By comparison, the assured recoverable reserves of coal represent 83 percent of the total assured recoverable reserves of all fuels. Although petroleum and natural 

gas now contribute more to the national fuel needs 

than coal, this trend eventually will be reversed as 

the smaller reserves of petroleum and natural gas 

become depleted. The total ultimately recoverable 

reserves of coal as of January 1, 1950, are 1, 612 

times the average annual production during the period 

1940 to 1950. Assuming a great increase in coal 

production, these reserves still will last many generations. On any basis of analysis the coal reserves of 

the United States are very large by comparison with 

all other known available sources of heat, light, and 

power and give comfortable assurance that the future 

fuel needs of the Nation can be met in any contingency. 

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33 

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