. Bituminous Coal 

Resources of Texas

\ By W. J. MAPEL

CONTRIBUTIONS TO ECONOMIC GEOLOGY

GEOLOGICAL S U R.V E Y BULLETIN 1242-D

v A review of the occurrence of bituminous

and cannel coal in Texas and a new 

-/* estimate of the original coal resources

» UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1967
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEWART L. UDALL, Secretary

GEOLOGICAL SURVEY 

William T. Pecora, Director

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

Washington, D.C. 20402 - Price 15 cents (paper cover)
CONTENTS

	Page 

Abstract -- .___.______________________ Dl

'-* Introduction. ____________________________________________________ 1

Location. __-_-------_--________________._____________________ 1

Purpose of report -- --_---__-__-_________-____.___________ 2

Sources of information._._.._..._.___________________________ 3

Paleozoic coal deposits......____._____.____.__._______..__.____._ 5

Geologic setting--------------__-_-_-_-_-____________________ 5

Occurrences of coal__-___-____-____________________,___________ 6

-, Rocks of Atoka age ___________________________________ 6

Strawn Group _______________________________________ 8

Thurber coal bed_._-_.____________________.___________ 9

Other coal beds__-___---__________________________ 10

/* Canyon Group________.__.________________________________ 12

j Bridgeport coal bed ...^............................. 12

Dalton coal bed.______________________________________ 12

Other coal beds.__-_------_-_-_____ _______--_-______ 13

Cisco Group______--_____-_-_-_-_-______-______-___-___-__ 14

Graham Formation.___________________________________ 15

Thrifty Formation .__.____________-_-_____---_-______ 15

Wichita Group__________----_____--__-_-_______-_--___-___ 16

Bull Creek coal and approximately equivalent beds._______ 18

r> Newcastle coal and approximately equivalent beds_ T _______ 20

Saddle Creek coal and approximately equivalent beds.__-_- 21

Cretaceous and younger coal deposits. _____________ ........... _______ 21

,_j Eagle Pass district_______.___-_-___-_-.___-___.__-_--_-----_- 21

Santo Tomas district________________-___-_-_ _-__-----_-_--- 21

Other areas._-_-----_-----_---------------------_-- _-_----. 23

Coal production._.__._.___._____--_______-____________----------_- 23

-*1 Coal resources tabulated by areas and beds-_____-________,_------__-- 24

References cited______________________________-_---_------------- 26

in
IV CONTENTS

ILLUSTRATIONS

Page 

FIGURE 1. Index map showing bituminous and cannel coal districts

in Texas_. _________-----__ ---- -- D2

2. Map showing structural elements, and location of wells for 

which sample logs were examined for coal, north-central 

Texas..__-______-___--____________ 4

3. Generalized geologic map, north-central Texas_-_---____- 5

4. Chart showing some stratigraphic units in the Brazos River

area.__-_______--_---_-__---_-----__-------------_ 7

5-14. Maps showing distribution of coal beds:

5. Rocks of Atoka age.-__-_--_-----------_------ 8

6. Thurber and approximately equivalent coal beds.. 10

7. Strawn Group, other than the Thurber coal bed__ 11

8. Bridgeport and approximately equivalent coal

beds.__- --- - - __ _ 13

9. Canyon Group, other than the Bridgeport coal

bed -__----- - - - - - - 14

10. Graham Formation.-----.___----_-------_---_ 16

1.1. Thrifty Formation---------.------------------ 17

12. Bull Creek and approximately equivalent coal

beds------ ---------------.-_-__--.-_-. 18

13. Newcastle and approximately equivalent coal beds. 19

14. Saddle Creek and approximately equivalent coal

beds..---___--_-___-_--_---___-___-_-.-_ 20

TABLES

. Page 

TABLE 1. Bituminous coal production in Texas, 1895-1943.-------- D24

2. Inferred original resources of bituminous coal in northcentral Texas.-_--_-______--_-_____-_----__________ 25

3. Inferred original resources of bituminous and cannel coal in 

Maverick and Webb Counties and part of Presidio 

County, Texas.-.------- -__------------__---___-_ 25

4. Summary of original bituminous and cannel coal resources

in Texas._---_._-----_---_- -_---__-_----._.-..__._ 26
CONTRIBUTIONS TO ECONOMIC GEOLOGY

BITUMINOUS COAL RESOURCES OF TEXAS

By W^ J. MAPEL

Occurrences of coal reported in sample logs of wells drilled for oil and gas are 

plotted for eight beds or intervals in Pennsylvanian rocks and for three in Lower 

Permian rocks. This information is combined with published thickness measurements of coal at outcrops to give a new estimate of 5,400 million short tons of 

bituminous coal inferred to be present in Paleozoic rocks of north-central Texas 

in beds more than 14 inches thick and under less than 3,000 feet of overburden. 

Of this total, 3,400 million short tons is inferred to lie under less than 1,000 feet of 

overburden.

An additional 525 million short tons of bituminous coal of Cretaceous age is 

inferred to underlie the Eagle Pass district in Maverick County; 115 million short 

tons of cannel coal is inferred to underlie the Santo Tomas district, Webb County; 

25 million short tons of bituminous, coal is inferred to underlie the San Oarlos 

district, Presidio County; and 65 million short tons of coal is estimated as a 

potential resource in areas, largely unexplored for coal, underlain by the Aguja 

Formation (Upper Cretaceous) in Brewster and Presidio Counties.

The combined total of these estimates is about 6,100 million short tons of 

bituminous and cannel coal in Texas in beds more than 14 inches thick and under 

less than 3,000 feet of overburden.

INTRODUCTION

LOCATION

Bituminous coal occurs locally in rocks of Pennsylvanian and Early 

Permian age in north-central Texas in an area of several thousand 

square miles bounded approximately on the east and west by longs 

97° E. and 100° E., respectively, and extending from the northern side 

of the Llano region at about lat 31° N. north to the Oklahoma border 

at about lat 34° N. About 90 percent of the accessible bituminous coal 

known in the State is within this area. Other deposits are of Cretaceous age and occur in southern Texas adjacent to the Kio Grande, 

principally at Eagle Pass in Maverick County, but also at scattered 

places in Hudspeth, Presidio, and Brewster Counties (Andrews and 

Huddle, 1948, p. 6) as shown in figure 1.

Dl
D2 CONTRIBUTIONS TO ECONOMIC GEOLOGY

105°

Paso

\.3 

\

+( 30'

100

L_

FIQUKB 1. Bituminous and cannel coal districts in Texas. 1, North-central 

Texas; 2, Eagle Pass district, Maverick County; 3, Eagle Spring area, Hud»- 

peth County; 4, San Carlos district, Presidio County; 5, Terlingua district, 

Brewster County; 6, Santo Tomas district, Webb County (cannel coal). 

Known coal-bearing areas for which resources are estimated are sihown 

stippled.

Cannel coal is found in rocks of early Tertiary age in the Santo 

Tomas district, Webb County. These deposits have been regarded as 

part of the bituminous coal resources in most previous reports on 

Texas coal, and they are included in the present report.

PURPOSE OF REPORT

The resource estimate of 8,000 million short tons of bituminous coal 

usually quoted for Texas was made prior to 1910 by Campbell and 

Parker (1909, p. 24), and was based on very generalized information 

on the areal and stratigraphic distribution of the coal. Campbell
BITUMINOUS COAL RESOURCES OP TEXAS D3

and Parker (1909, p. 24), and Campbell (1913,1917,1929) in later reports, did not specify the average thickness of coal assumed in their 

calculations, nor did they itemize resources for individual beds or 

areas. Some writers, including Andrews and Huddle (1948, p. T) and 

Averitt (1961, p. 78), suggested that the Campbell estimate is probably 

too large. Until recently, however, information for making any better assessment of the resources was lacking.

From 1963 to 1965, several hundred commercial sample logs of wells 

drilled for oil and gas were examined by the author as part of an investigation of the regional stratigraphic relations of the Pennsylvanian 

System in north-central Texas. Information on the occurrence of coal 

as reported in the logs was plotted for eight 'beds or intervals in 

Pennsylvanian rocks and for three in Permian rocks. The resulting 

maps outline the distribution of Paleozoic coal beds more precisely 

than have any previous reports. This information is combined with 

published thickness measurements to give a new estimate for bituminous coal resources in north-central Texas.

A total coal-resource estimate is made for bituminous and cannel 

coal in Cretaceous and lower Tertiary rocks to complete the survey of 

the bituminous coal deposits of the State.

In conformity with the standard practice of the U.S. Geological 

Survey (Averitt, 1961, p. 18, 20-21), the estimates do not include 

bituminous coal in beds thinner than 14 inches or beneath more than 

3,000 feet of cover. Perkins and Lonsdale (1955) and Fisher (1963) 

discussed the lignite resources of Texas; coal of this rank is excluded 

from resource estimates in this report.

SOURCES OF INFORMATION

Most of the sample logs used in outlining coal bearing areas in northcentral Texas were made by the Abilene Sample Log Service, Abilene, 

Tex., and the North Texas Sample Log Service, Wichita Falls, Tex. 

Selected logs made by the following Texas companies were also examined: Permian Basin Sample Laboratory, Midland; Texas Panhandle Sample Log Service, Amarillo; and West-Central Texas Sampie Log Service, Abilene. Wells logged by these three companies are 

generally marginal to the main coal-bearing areas. The location of 

the wells for which logs were examined is shown in figure 2. All 

sample logs were drawn at a scale of 1 inch = 100 feet.

The distance between wells for which logs were examined averages 

about 10 miles. This spacing is dense enough to outline broadly the 

major coal deposits, but it is not sufficient to show details of coal distribution within the coal-bearing region.
FIGURE 2. Structural elements, and location of wells for which sample logs were 

examined for coal, north-central Texas.

Published reports of the Texas Bureau of Economic Geology, the 

U.S. Geological Survey, and the U.S. Bureau of Mines provided information on the thickness and the chemical and physical characteristics of the coal at outcrops, in mines, and in a few drill holes. Fairly 

complete tabulations of analyses are given by Baker (1934) and by 

Cooper, Snyder, Abernethy, and Tarpley (1948).

Information on Cretaceous and younger coal in the Eagle Pass, 

Santo Tomas, and other districts comes mainly from Vaughan (1900), 

Ashley (1918), Baker (1934, p. 316-329), and Lonsdale and Day 

(193Y).
BITUMINOUS COAL RESOURCES OF TEXAS D5 

PALEOZOIC COAL DEPOSITS 

GEOLOGIC SETTING

Outcropping Pennsylvanian and lowermost Permian coal-bearing 

rocks form a discontinuous irregular band as much as 70 miles wide 

that extends from the north edge of the Llano region northeastward 

to within about 20 miles of the Oklahoma border (fig. 3). To the 

west, these rocks dip at low angles beneath younger Permian rocks; 

to the east, they are overlain unconf ormably by eastward-dipping rocks 

of Cretaceous age.

0 25 50 MILES

I_____I HALL CHILDRESS v fv

I \./-sJ N

ri_______,_!_______I f

I , J2 HARDEMAN

FIGUBE 3. Generalized geologic map, north-central Texas. Cretaceous rocks, 

light stipple; Triassic and Permian rocks, no pattern; Pennsylvanian rocks, 

heavy stipple; pre-Pennsylvanian rocks, diagonal rule.

239-605 O 67-
D6 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Structural elements that governed distribution of the coal deposition early in Pennsylvanian time in north-central Texas were, principally, the Fort Worth basin and the positive elements that bordered 

it. These elements were the Ouachita structural belt on the east, the 

Muenster and Red River arches on the north, and the Concho shelf 

on the west. (See fig. 2.) Coal was deposited during Early Pennsylvanian time in the northern part of the Fort Worth basin and in a 

belt along the north side of the Red River arch. Beginning in about 

Middle Pennsylvanian time, the area of the Fort Worth basin was 

mostly emergent, and coal formed locally and intermittently on the 

Concho shelf. This coal region was bordered on the west by a sea in 

the sinking Midland basin, and on the north by highlands that rose 

first in north Texas and later in Oklahoma.

Turner (1957) and Adams (1962) discussed in more detail the regional stratigraphic relations of the Pennsylvanian rocks in northcentral Texas.

OCCURRENCES OF COAL

Pennsylvanian coal is found in rocks of Atoka age, and in the 

Strawn, Canyon, and Cisco Groups. These rocks correspond closely 

to the Atoka, Des Moines, Missouri, and Virgil Series, respectively, 

of the standard Mid-continent terminology. Coal-bearing Permian 

rocks occur in the basal part of the Wichita Group of the Wolfcamp 

Series.

Coal is much more widespread in the Brazos River drainage basin 

than elsewhere in north-central Texas. Within the Brazos River region, however, the locus of coal deposition shifted gradually westward 

from the northeastern part of the Fort Worth basin during Atoka time 

to the north-central part of the Concho shelf in Early Permian time.

Figure 4 shows the stratigraphic positions of the main coal beds.

BOCKS OF ATOKA AGE

Rocks of Atoka age consist of limestone and sandy limestone, shale, 

sandstone, conglomerate, and minor amounts of coal. They range in 

thickness from zero along a somewhat indefinite line on the west side 

of the Concho shelf to about 6,000 feet in the Fort Worth basin in eastern Tarrant County, and they attain a thickness of as much as 665 feet 

north of the Red River arch in Hardeman County.

The main coal-bearing areas lie in the northern part of the Fort 

Worth basin, mostly in Wise and Denton Counties, and locally in Jack, 

northern Parker, and southern Clay Counties. Some coal is present, 

also, in a west-trending belt north of the Red River arch in Wilbarger, 

Hardeman, Cottle, Motley, and nearby Counties (fig. 5).
D7

AGE

1 tf £!

Pennsylvanian Late 

Middle Pennsylvanian 

(part)

GROUP

Wichita 

(part)

Cisco

Canyon

Strawn 

(part)

FORMATION

Pueblo 

(part)

Thrifty

Graham

Caddo 

Creek

Brad

Graford

Palo Pinto 

Limestone

Mineral 

Wells

Garner

Millsap 

Lake

MEMBER

Saddle Creek Limestone

Waldrip Shale

Crystal Falls Limestone [

(Chaff in Limestone in

| Colorado River area) |

Breckenridge Limestone

Blach Ranch Limestone

(Speck Mountain Limestone 1 

in Colorado River area) |

Ivan Limestone

Avis Sandstone

Wayland Shale

Gunsight Limestone

Bunger Limestone

Gonzales Limestone

Home Creek Limestone

Colony Creek Shale

Ranger Limestone

Placid Shale

Merriman Limestone 

n(Winchell Limestone in i 

Colorado River area) |

Adams Branch Limestone

Wiles Limestone

Turkey Creek Sandstone

East Mountain Shale

Brazos River Conglomerate

Mingus Shale

Grindstone Creek of Plummer 

and Hornberger (1935)

COAL BED

| Saddle Creek |

Newcastle |

_| Bull Creek in Colorado |_ 

| River area |

Chaffin in Colorado 

River area

| Dalton |

| Abbott |

J Thurber 1 

 1 Sunday Creek 1 

FIQTJBE 4. Some stratigraphic units in the Brazos River area.
D8 CONTRIBUTIONS TO ECONOMIC GEOLOGY

0 25 50 MILES

I______|______|

:.;V% :\H>^: : :\:-|c'ti/ftwe«S.-tv.- : >... -SJS

tmzmmmm^sL. °**-

im^-^^Qi,

M99° 98°

FIGUEE 5. Distribution of coal (stippled) in rocks of Atoka age.

Well logs examined by G. H. Dixon (written commun., 1965) show 

coal irregularly but widely distributed in rocks of Atoka age in the 

Panhandle of Texas immediately northwest of the area shown in figure 

5. Coal appears to be randomly distributed stratigraphically in all 

the areas in which it occurs ; no single persistent coal horizon was identified. The coal everywhere is 4,000 to more than 7,000 feet below the 

surface; hence, it is too deeply buried to be mined, and resources have 

not been calculated.

STBAWN GROUP

The Strawn Group is mostly sandstone and shale, but includes a few 

limestone beds, some conglomerate, and a few coal deposits, some of 

which have been mined. Some stratigraphic units in outcrops near 

the Brazos River are listed in figure 4. The nomenclature is largely
BITUMINOUS COAL RESOURCES OF TEXAS DO

that of Sellards (1932); some workers have amended this classification, 

one of the principal changes being that the top of the East Mountain 

Shale Member of the Mineral Wells Formation as used by Sellards 

(1932) is taken as the boundary between the Canyon and Strawn 

Groups (Canyon and Strawn Series of some writers), and is the 

boundary between Middle and Late Pennsylvanian rocks (Cheney, 

1940, 1945, 1947; Abilene Geol. Soc., 1949; Fort Worth Geol. Soc., 

1957 ;Shelton, 1958).

Where the Strawn is coal bearing, it ranges in thickness from about 

2,500 feet, as in southern Palo Pinto County, to 4,500 feet, as in the 

subsurface in eastern Denton County in the central part of the Fort 

Worth basin. The Strawn thins abruptly along the trend of the Red 

River and Muenster arches and is locally absent in the subsurface in 

northern Wichita and Clay Counties on the crest of the Red River arch.

Coal in the Strawn is most widespread in the northern part of the 

Fort Worth basin, in an area extending from Grayson County westward to Young County and from northern Clay County southward to 

Palo Pinto County; minor amounts exist in Callahan and Coleman 

Counties to the southwest. Near the Red River arch, in and near 

Wilbarger, Hardeman, Foard, Cottle, and Motley Counties, some coal 

is reported in well logs at or near the base of the Strawn, but this coal 

lies more than 3,000 feet underground and is not considered part of 

the coal resources.

THTJEBER COAL BED

The Thurber is the most extensive coal bed in outcrops of the 

Strawn. It was mined for many years in southern Palo Pinto County 

and in adjoining parts of Erath County, and in these places it occurs 

at or near the base of the Mingus Shale Member of the Garner Formation, about 600 feet below the top of the Strawn (Plummer and 

Hornberger, 1935, p. 195-203). A coal bed, which was mined locally, 

crops out near the middle of the Mingus Shale Member along Rock 

Creek in western Parker County. Plummer and Hornberger (1935, 

p. 195) correlated the coal at Rock Creek with the Thurber coal; Hendricks (1957, p. 20), however, considered the coal at Rock Creek to be 

slightly higher stratigraphically than the Thurber coal and probably 

not continuous with it. A coal bed that may be equivalent to the 

Thurber lies 1,400-1,500 feet below the top of the Strawn in the subsurface in Wise and Jack Counties (Scott and Armstrong, 1932, p. 17, 

pi. 2). The extent of the Thurber coal and approximately equivalent 

coal beds in the Mingus Shale Member as determined during the present 

work is shown in figure 6.

The Thurber coal is 26-36 inches thick where mined in northern 

Erath and southern Palo Pinto Counties (Plummer and Hornberger,
D10 CONTRIBUTIONS TO ECONOMIC GEOLOGY

50 MILES

FIGURE 6. Distribution of the Thurber and approximately equivalent coal beds 

(stippled)» Isopaehs show thickness of overburden, in feet. R, areas for 

w<hich resources are estimated (table 2).

1935, p. 198-199); it is 18-26 inches thick along Kock Creek in Parker 

County (Cummins, 1891, p. 519). No thickness figures are available 

for the coal in the subsurface in Jac^ and Wise Counties.

OTHER COAL BEDS

The Abbott coal bed (fig. 7), named and described by Plummer and 

Hornberger (1935, p. 194), is a discontinuous bed locally as much as 

26 inches thick that crops out in east-central Palo Pinto County; it is in 

the upper part of the Brazos River Conglomerate Member of the 

Garner Formation, about 200 feet stratigraphically above the Thurber 

coal bed (fig. 4). A bed at this position is also present locally in the 

subsurface in Jack and Wise Counties (Scott and Armstrong, 1932, 

pl.2).
BITUMINOUS COAL RESOURCES OF TEXAS Dll

I

 '- ^._ , I

FIGURE 7. Distribution of coal (stippled) in the Strawn Group, other than the 

Thurber coal bed. R, areas for which resources are estimated (table 2).

The Sunday Creek coal bed in southeastern Palo Pinto County, also 

named and described by Plummer and Hornberger (1935, p. 203), is 

in the lower part of their Grindstone Creek Member of the Millsap 

Lake Formation, about 220 feet stratigraphically below the Thurber 

coal. This bed is apparently in the same shale interval, but it is somewhat higher stratigraphically than a thin coal Scott and Armstrong 

(1932, pi. 2) reported in Jack and Wise Counties within the Millsap 

Lake Formation. The Sunday Creek coal bed is 18-22 inches thick at 

its outcrop in Palo Pinto County (Plummer and Hornberger, 1935, 

p. 203).

Discontinuous coal stringers are found at a few other levels in the 

Strawn in Jack, Wise, and adjoining Counties. One well in eastcentral Jack County contains 10 thin coal beds in a sequence of rocks 

2,300 feet thick beginning about 1,500 feet below the top of the Strawn.
D12 CONTRIBUTIONS TO ECONOMIC GEOLOGY

In Grayson County, east of the area shown in figure 7, coal occurs fairly 

commonly in the Strawn Group, but at depths of several thousand 

feet. Thicknesses of these coal lenses are unknown, and none of the 

lenses has been considered in calculating the coal resources.

CANYON GROUP

The Canyon Group consists of ridge-forming beds of limestone separated by shale, sandstone, and, locally, some coal. The group attains 

a maximum thickness of about 1,300 feet in Clay and Montague Counties and thins gradually and somewhat irregularly from this area 

southwestward across north-central Texas at about 10-15 feet per 

mile. Stratigraphic divisions of the Canyon Group at outcrops along 

the Brazos Kiver are given in figure 4.

Several coal beds occur in the Canyon Group, the most persistent 

being the Bridgeport coal and approximately equivalent beds in the 

northern part of the Fort Worth basin and on adjoining parts of the 

Red Eivee, arch.

BRIDGEPORT COAL BED

The Bridgeport coal crops out near the town of Bridgeport in 

western Wise County. It is in the upper part of the Palo Pinto Limestone about 1,300 feet below the top of the Canyon Group (Scott and 

Armstrong, 1932, p. 26). The same 'bed, or perhaps separate lenses of 

coal at about the same stratigraphic position, was identified in sample 

logs of wells in two irregularly shaped areas in parts of Wise, Montague, Jack, Young, and southern Clay and Archer Counties (fig. 8). 

Separate smaller areas in northern Clay and eastern Wichita Counties 

also contain some coal at about the top of the Palo Pinto, which there 

is 1,000-1,100 feet below the top of the Canyon. The coal was once 

mined near Bridgeport, where it consists of a single bed 18-22 inches 

thick (Scott and Armstrong, 1932, p. 72). Other measurements of the 

coal have not been reported.

DALTON COAL BED

The Dalton coal was named by Plummer and Hornberger (1935, p. 

192-193). It is a bed in their Wolf Mountain Shale Member of the 

Graford Formation, a name they gave to that part of the Graford 

Formation below the Merriman Limestone Member. The coal is 150- 

160 feet below the top of the Merriman Limestone Member and about 

500 feet belpw the top of the Canyon Group in northwestern Palo 

Pinto County (fig. 9). Plummer and Hornberger (1935, p. 193) 

traced the bed along its outcrop for about 4 miles, and at one locality 

measured a thickness of 9 feet 8 inches of coal in the bed. Coal was 

not identified at this horizon in the logs examined during the present
BITUMINOUS COAL RESOURCES OF TEXAS D13

work; therefore, despite its unusual thickness, the bed is probably 

confined to the immediate vicinity of its outcrop.

OTHER COAL BEDS

Well logs show that coal occurs fairly commonly in the Canyon 

Group in the northern part of the Fort Worth basin and on the adjoining east side of the Concho shelf (fig. 9). None of the beds appear to 

be very persistent, and the sample descriptions on the well logs examined in this investigation suggest that the coal is thin everywhere. 

The coal beds occur in the upper part of the Placid Shale Member of 

the Brad Formation and in the upper part of the Colony Creek Shale 

Member of the Caddo Creek Formation. Coal in these beds was not 

considered in the resource calculations.

II FOAKU | WICHQA

0

! CLAY

-K -~ -fc Ay*? /[

i \/ e.

-+ -h --h ,L____

FIGURE 8. Distribution of the Bridgeport and approximately equivalent coal beds 

(stippled). Isopachs show thickness of overburden, in feet. R, area for which 

resources are estimated (table 2).
D14 CONTRIBUTIONS TO ECONOMIC GEOLOGY

FIGURE 9. Distribution of coal (stippled) in the Canyon Group, other than the 

Bridgeport coal 'bed. R, area for which resources are estimated (table 2).

CISCO GROUP

The Cisco Group consists of shale, lenticular sandstone, many thin 

beds of limestone, and minor amounts of coal. In the area studied the 

group ranges in thickness from a maximum of about 1,200 feet, in the 

subsurface in northern Wlchita and Wilbarger Counties, to about 350 

feet, in outcrops along the west side of the Llano region in Brown and 

Coleman Counties. Stratigraphic divisions of the group in outcrops 

in the Brazos River region are shown in figure 4. The coal is found at 

several horizons in the Cisco Group, but mostly in the part that lies 

above the Gunsight Limestone Member of the Graham Formation. 

Coal is more common in the subsurface than along the outcrop, where 

only a few thin stringers of coal have been reported.
BITUMINOUS COAL RESOURCES OF TEXAS D15 

GRAHAM FORMATION

The Graham Formation, at the base of the Cisco Group, is about 260 

feet thick along its outcrop in Coleman County (Eargle, 1960, pi. 26), 

about 675 feet thick in outcrops near the Stephens-Young County 

boundary (Lee, 1938, pi. 4), and about 900 feet thick in the subsurface 

in Baylor County. Coal in irregular discontinuous lenses is fairly 

common in the formation (fig. 10). Coal is most common at the base 

of the formation, just above the Home Creek Limestone Member of the 

Caddo Creek Formation; within a few feet of the top of the unit that 

underlies-the Gunsight Limestone Member (Necessity Shale Member of Sellards, 1932); and at the top of the formation, just below 

the Speck Mountain or Blach Ranch Limestone Member of the 

Thrifty Formation. A lens of coal at the top of the formation in 

outcrops in northwestern Brown County is 3^-6 inches thick (Eargle, 1960, p. 71; Stafford, 1960, p. 46). Lee (1938, p. 59) reported 6 

inches of coal at this horizon along the Brazos River in southern 

Young County. No other thickness measurements of coal in the 

formation are available; and coal in the Graham Formation, therefore, is nowhere known to be thick enough to be considered in the coal 

resources.

THRIFTY FORMATION

The Thrifty Formation is about 60 feet thick in outcrops in Coleman County (Eargle, 1960, pi. 26); equivalent rocks are about 105 

feet thick in outcrops in northern 'Stephens County (Brown, 1960, 

pi. 3), and about 200 feet thick in the subsurface in Baylor and adjoining Counties. Coal is more common in the Thrifty than in the underlying Graham Formation. The principal coal horizon in outcrops and 

in the subsurface is within or just below the Crystal Falls or Chaffin 

Limestone Member of the Thrifty, although coal is also present locally 

in other parts of the formation.

The Chaffin coal bed, which was named by Drake (1917, p. 62) for 

its occurrence at the Chaffin mine 2 miles east of Waldrip in McCulloch County (fig. 11), lies immediately below the Chaffin Limestone 

Member of the Thrifty Formation. The bed is 20 inches thick at the 

mine (Drake, 1917, p. 64); however, it has not been found in outcrops 

nearby (Drake, 1917, p. 63; Eargle, 1960, pi. 3), and it is apparently 

a small lens.

In northern Stephens County at two localities about %y2 miles 

apart, as much as half a foot of coal was reported by Brown (1960, 

p. 33, 34) in a bed just below the Crystal Falls Limestone Member of 

the Thrifty Formation, within the top 5 feet of the Quinn Clay of 

Plummer, Bradley, and Pence (1949). This coal is at the stratigraphic 

position of the Chaffin coal bed. Coal is fairly widespread at this
Die CONTRIBUTIONS TO ECONOMIC GEOLOGY

50 MILES

101° 100° 99' 98'

FIGURE 10. Distribution of coal (stippled) in the Graham Formation.

horizon in the subsurface on the northern part of the Concho shelf in 

Throckmorton, Baylor, Wilbarger, and some adjoining Counties, but 

the thickness of the coal in the subsurface is not known.

WICHITA GROUP

Coal occurs in the Wichita Group in the Waldrip Shale Member of 

the Pueblo Formation. According to the classification by Eargle 

(1960, pi. 27), the Waldrip overlies the Chaffin or the Crystal Falls 

Limestone Member of the Thrifty Formation and is overlain by the 

Saddle Creek Limestone Member of the Pueblo Formation. Some 

other writers place the Waldrip and equivalent beds in the upper part 

of the Harpersville Formation (Plummer and Moore, 1921; Lee, 1938; 

Nickell, 1938; Brown, 1960). The name Harpersville is not used in 

Eargle's (1960) nomenclature.
BITUMINOUS COAL RESOURCES OF TEXAS Dl,7

101

FIGUBE 11. Distribution of coal (stippled) in the Thrifty Formation. R, area 

for which resources are estimated (table 2).

The Waldrip Shale Member of the Pueblo Formation is predominantly shale, most of which is gray .but some of which is red; it also 

contains lenticular beds of sandstone, and generally one or more thin 

beds of limestone. The member is 100 to about 200 feet thick in Brown 

and Coleman Counties (Eargle, 1960, pi. 26) and approximately the 

same thickness in outcrops in the Brazos River drainage area farther 

north (Myers, 1965; Lee, 1938, pi. 10); the member thickens to as much 

as 275 feet in the subsurface in Baylor and nearby Counties.

Three coal-bearing zones can be recognized in the Waldrip Shale 

Member of the Pueblo Formation; all three are fairly widespread in 

the subsurface, as shown in figures 12-14.
D18 CONTRIBUTIONS TO ECONOMIC GEOLOGY

The Bull Creek coal bed and other coal lenses at about the same 

stratigraphic position crop out in the lower part of the Waldrip Shale 

Member 24-50 feet above the Chaffin Limestone Member of the Thrifty 

Formation in southern Coleman County (Drake, 1917, p. 49). According to Drake (1917, p. 49), the coal bed ranges in thickness from 

12 to 30 inches. The coal was formerly mined at Bull Creek, a mile or 

two north of the Colorado River (fig. 12), where Nickell (1938, p. 130) 

reported the thickness as "about 1 foot, and nowhere more than 15 

inches."

Lee (1938, p. 65-66) reported nearly 6 feet of impure coal in thin 

layers alternating with carbonaceous shale in the lower part of the

0 25 50 MILES

I______I______I

FIGUBE 12. Distribution of Bull Creek and approximately equivalent coal beds 

(stippled). Isopachs show thickness of overburden, in feet. K, area for which 

resources are estimated (table 2).
BITUMINOUS COAL RESOURCES OF TEXAS D19

Waldrip (the Curry Clay of Plummer and others, 1949) near Crystal 

Falls in northwestern Stephens County, and 4 feet of coal and shale 

about 10 miles to the northeast in southern Young County. Brown 

(1960, fig. 6) described the principal coal layer at the Crystal Falls 

locality as being iy2 feet thick, and the remainder of the bed as mostly 

carbonaceous shale. This coal is 15-20 feet above the Crystal Falls 

Limestone Member of the Thrifty Formation, which is approximately 

the stratigraphic position of the Bull Creek coal bed of Coleman 

County with which it is correlated. The extent of coal at the horizon 

of the Bull Creek coal bed is shown in figure 12.

0 25 50 MILES

I______I

FIGURE 13. Distribution of the Newcastle and approximately equivalent coal 

beds (stippled). Isopachs show thickness of overburden, in feet. R, areas for 

which resources are estimated (table 2).
D20 CONTRIBUTIONS TO ECONOMIC GEOLOGY

NEWCASTLE COAL AND APPROXIMATELY EQUIVALENT BEDS

The Newcastle coal bed, which was mined for several years at Newcastle in central Young County (fig. 13), is about 60 feet below the 

top of the Waldrip Shale Member of the Pueblo Formation. In the 

terminology used by some writers (Criswell, 1942; Brown, 1960), the 

bed is in the lower part of the sequence between the so-called Upper 

Crystal Falls Limestone and the Belknap Limestone Member of Plummer and Moore (1921) of the Harpersville Formation. The Newcastle coal bed is 18^8 inches thick in outcrops near the mines and in 

wells drilled in western Young County several miles from the mines 

(Criswell, 1942, p. 2).

In the northwestern part of Eastland County, two coal beds, 3 feet 

and 2i£ feet thick, occur in the middle part of the Waldrip Shale

! HALL CHILDRESS "v _ t\. 

rl ,_! I ' V

I * I MARHFMAM I

0 25 50 MILES

I______I______I

47 ">"(A

/I \/ I

MONTA<SllE"V C °° KE «

/ ^-Nl^-^^S |0 

 ^. 1 , z

FIGURE 14 Distribution of the Saddle Creek and approximately equivalent coal 

beds (stippled). Isopachs show thickness of overburden, in feet.
BITUMINOUS COAL RESOURCES OF TEXAS D21

Member, 45 and about 70 feet, respectively, below the top of the member (C. A. Hamill, in Plummer and Moore, 1921, p. 164). The upper 

bed is 26 inches thick about 1 mile northwest of Cisco and is probably 

the Newcastle coal, according to Plummer, Bradley, and Pence (1949, 

p. 21, fig. 16). Figure 13 shows the distribution of the Newcastle coal 

and approximately equivalent coal beds in the middle part of the Waldrip Shale Member.

SADDLE CREEK COAL AND APPROXIMATELY EQUIVALENT BEDS

A coal bed that locally occurs within the top few feet of the Waldrip 

Shale Member of the Pueblo Formation, immediately below the Saddle 

Creek Limestone Member, is referred to here as the Saddle Creek coal 

bed. In outcrops, the Saddle Creek coal bed is reported only in the 

southeast corner of Young County, where it consists of a few thin coal 

streaks (Lee, 1938, p. 72). In the subsurface, the bed is widespread 

(fig. 14). Shenkel (1960, p. 179) found coal, or a bed of carbonaceous 

shale, at this interval to be 1-2 feet thick in much of Taylor and Callahan Counties. His thickness measurements were computed from the 

lateral resistivity curves of electric logs of wells; no other thickness 

measurements of the coal are available. Resources were not calculated 

for this bed.

CRETACEOUS AND YOUNGER COAL DEPOSITS

EAGLE PASS DISTRICT

Bituminous coal crops out in the Eagle Pass district, Maverick 

County (fig. 1), in the Olmos Formation of Late Cretaceous age. The 

Olmos Formation, where coal bearing, ranges in thickness from 400 to 

600 feet. Coal occurs in a bed a little below the middle of the formation. The coal, excluding shale and bone partings, is 41/£-7 feet thick 

and averages 6 feet in thickness at seven localities along and near Elm 

Creek, 3-8 miles northeast of Eagle Pass; it is 6-7 feet thick in 

a water well about 2 miles south of Eagle Pass (Vaughan, 1900, p. 

57-59). Where it was mined in the district the bed has an average 

thickness of about 4 feet, including partings (Baker, 1934, p. 318). 

The coal splits into several bony benches, thins out to the east and is 

known to be minable in a belt extending no more than 15 miles east of 

Eagle Pass (Andrews and Huddle, 1948, p. 5).

SANTO TOMAS DISTRICT

The Santo Tomas field, Webb County (fig. 1), has been included in 

the bituminous coal districts of Texas by Campbell and Parker (1909), 

by Baker (1934), and by Andrews and Huddle (1948). This field
D22 CONTRIBUTIONS TO ECONOMIC GEOLOGY

contains minable deposits of cannel coal in the Mount Selman Formation of Eocene age. These coals have chemical and physical properties unlike those of the bituminous coals elsewhere in Texas, and 

although included with the bituminous coals for the purposes of resource estimates, they probably should be classified separately. Descriptions of the deposits and their stratigraphic relations were given 

by Vaughan (1900), Ashley (1918), and Lonsdale and Day (1937).

The thickest coal in the district is the Santos Tomas coal bed, 

which commonly is 24-36 inches thick and which averages about 

24 inches in thickness for a distance of 6-8 miles along its outcrop 

in bluffs along the Rio Grande between Dolores and Palafox 

(Ashley, 1918, p. 265-266). These thickness figures exclude 2-14 

inches of bony coal commonly found at the bottom of the bed. In the 

northern part of its outcrop, the Santo Tomas coal bed separates into 

four or five thinner coal beds that are lignite at some places and cannel 

coal at others (Lonsdale and Day, 1937, p. 34); the bed is not exposed 

north of Palafox.

Other deposits of cannel coal in the district are in the San Pedro 

coal bed, which is about 90 feet below the Santo Tomas coal bed in 

mines near Dolores. Ashley (1918, fig. 41) noted that in the mine 

workings and in a drill hole near the mines, the San Pedro contains 

about 2 feet of coal in an upper bench and as much as 19 inches of coal 

in a lower bench, the two benches being separated by about 2 feet of 

shale. The San Pedro coal bed is absent in exposures of the Mount 

Selman Formation near the mines. However, coal correlated with 

the San Pedro crops out at Palafox, 11 miles northwest of Dolores 

(Ashley, 1918, p. 267; Lonsdale and Day, 1937, p. 74); and a bed of 

cannel coal, or, locally, several thin beds of lignite, occupy the general 

zone of the San Pedro coal bed discontinuously from Palafox northward for about 15 miles (Lonsdale and Day, 1937, pi. 1, p. 21).

Dumble (1892, p. 188-189) and Ashley (1918, p. 268) suggested 

that coal of the Santo Tomas district extends underground across most 

of Webb County and into the eastern parts of Dimmit and Zavala 

Counties to the north. Lonsdale and Day (1937, pi. 1) indicated, 

however, that in outcrops the cannel coal is not persistent for any 

great distance. They reported that drilling in the northwestern part 

of Webb County gives no evidence of cannel coal there. Moreover, 

some of the coal beds in Zavala County that Dumble considered to be 

correlative with the Santo Tomas and San Pedro coal beds are lignite 

beds now known to be older (Fisher, 1963, p. 78-79).

Resources of cannel coal calculated for the present report are for an 

area extending not more than 10 miles into Texas from a point on the 

Rio Grande midway between Dolores and Palafox.
BITUMINOUS COAL RESOURCES OF TEXAS D23 

OTHER AREAS

Coal occurs in Cretaceous rocks in Brewster, Presidio, and Hudspeth 

Counties (fig. 1), but it cannot be traced beyond local areas. All this 

coal is characterized by a high ash content (Andrews and Huddle, 

1948, p. 6).

The Brewster County deposits, which are near Terlingua in the 

southern part of the county, consist of coaly zones at the base of and 

in the upper part of the Aguja Formation of Late Cretaceous age 

(Yates and Thompson, 1959, p. 14^15). Baker (1934, p. 322) reported 

coal as much as 18 inches thick at three closely spaced localities about 

15 miles east of Terlingua and at one locality about 10 miles south of 

Terlingua. According to Baker (1934, p. 321), the coal is altered to 

anthracite at a few places where it is cut by igneous rocks.

In the San Carlos district (northwestern Presidio County) two coal 

beds, each about 2 feet thick and separated by as much as 8 feet of 

claystone and sandstone, were traced for at least 2 miles during early 

prospecting and mining (Vaughan, 1900, p. 77-79, pi. 6). The coalbearing rocks in this area were assigned to the Aguja Formation by 

Baker (1934, p. 321).

In Hudspeth County the principal coal occurrence is at Eagle 

Spring on the north side of the Eagle Mountains, and is in the Upper 

Cretaceous Eagle Ford Formation (Gillerman, 1953, p. 32). A coal 

bed as much as 3 feet thick has been exposed by mining at this locality 

(Baker, 1927, p. 67). No information is available on the extent of 

the coal; but as coal has not been reported in the Eagle Ford elsewhere in the region, the area in which coal is more than a few inches 

thick is assumed to be small.

COAL PRODUCTION

Bituminous coal produced in Texas from 1895 to 1943 totaled slightly 

more than 24 million short tons (table 1). Cannel coal mined in Webb 

County is called bituminous coal in the statistical reports and is included in this production figure. For the 11-year period preceding 

1895, the total amount of coal mined in Texas was 1,943,500 tons, including both bituminous coal and lignite (Phillips and Worrell, 1913, 

p. 11-12). Separate records were not kept for .these two ranks of coal 

prior to 1895; however, production trends for the 5 years following 

1895 suggest that about two-thirds of the pre-1895 tonnage, or about 

1,300,000 short tons, was bituminous coal, and the remainder was 

lignite.

The peak year for production of bituminous coal in Texas was 1913, 

when 1,247,988 short tons was mined. Yearly production dropped be-
D24 CONTRIBUTIONS TO ECONOMIC GEOLOGY

low 100,000 tons in 1930, and the mining of bituminous coal virtually 

ceased by 1944.

TABLE 1. Bituminous coal production in Texas, 1895-1943

[Data summarized from U.S. Geol. Survey (1895-1&23) and from U.S. Bur. Mines

(1924-43)]

Production Production

(thousands (thousands

 of short of short

Years tons) Years tons)

1895-99 _____________._ 2,337 1925-29 ______.________ 738

1900-04 ______.________ 3,650 1930-34 ________________ 222

1905-09 ______.________ 4,749 1935-39 ________________ 169

1910-14 ______.________ 5,759 1940-43 ________________ 52

1915-19 ________________ 5,290 

1920-24 _______________ 1,360 Total __._____ 24,326

Original resources of bituminous and cannel coal in Texas are estimated to total 6,100 million short tons in beds more than 14 inches 

thick and under less than 3,000 feet of overburden. Of this amount, 

5,400 million short tons, or about 88 percent, is coal of Pennsylvanian 

and Permian age in north-central Texas; 665 million short tons, or 

about 11 percent, is coal of Cretaceous or early Tertiary age in the 

Eagle Pass, Santo Tomas and San Carlos districts; and 65 million 

short tons, or about 1 percent, is coal of Cretaceous age that may exist 

in parts of Brewster and Presidio Counties where the extent of the 

coal beds is poorly known.

About 3,400 million short tons, or about 65 percent, of the Pennsylvanian and Permian coal is under less than 1,000 feet of overburden. 

Information on the depth to coal in 'Cretaceous and lower Tertiary 

rocks is less detailed than for Pennsylvanian and Permian rocks, but at 

least half of the Cretaceous and Tertiary coal for which resources are 

calculated is less than 1,000 feet underground.

Tables 2 and 3 itemize the resources of each coal bed for which reliable thickness measurements of coal are available. The areas in 

north-central Texas for which the resources are estimated are shown 

in figures 6-9 and 11-13. All the resources are classified as inferred 

according to definitions discussed by Averitt (1961, p. 21-22) and used 

by the U.S. Geological Survey for resource estimates for other States.

Density of drilling in most of Texas seems sufficient to identify and 

outline coal deposits in Paleozoic rocks. It is unlikely that any undiscovered coal-bearing areas would be large enough to add appreciably 

to the total bituminous-coal resources.

Cretaceous rocks are less adequately explored for coal. The nonmarine Aguja Formation is present either at the surface or under fairly
BITUMINOUS COAL RESOURCES OF TEXAS D25

TABLE 2. Inferred original resources of bituminous Goal (Paleozoic) in northcentral Texas 

[In beds >14 in. thick and under <3,000 ft of overburden; 1,160,000 short tons of coal per square mile-foot]

Group

Wichita... ...

Cisco.. .......

Canyon. ___ . ......

Strawn . .... .........

Totals (rounded) 

Qrand total (roun

Coal bed

Bull Creek..................

Abbott-- 

ided). ...... ..................

Overburden 

(feet)

0-1,000

1,000-2,000 

2,000-3,000 

0-1,000 

1,000-2,000 

2,000-3,000 

0-1,000 

1,000-2,000 

2,000-3,000 

0-1,000 

1,000-2,000 

2,000-3,000 

0-1,000 

1,000-2,000 

2,000-3,000 

0-1,000 

1,000-2,000 

2,000-3,000 

0-1,000 

1,000-2,000 

2,000-3,000 

0-1,000 

1,000-2,000 

2,000-3,000

0-1,000 

1,000-2,000 

2, 000-3, 000

Thickness 

(feet)

2.5 

1.6

1.2 

1.2.

1.6

3.0

1.6 

1.2 

1.2 

1.7

2.0 

1.6 

1.6 

1.7

Area 

(square 

miles, 

rounded)

450 

150

180 

30

1

5

145 

295 

30 

3

650 

610 

370

7

Resources 

(millions of 

short tons, 

rounded)

1,300 

260

260 

41

2

17

250 

410 

41 

6

1,260 

880 

640 

14

3,400 

1,300 

680

5,400

TABLE 3. Inferred original resources of bituminous and cannel coal (Cretaceous 

and younger), in Maverick and Webb Counties and part of Presidio County, 

Tex.

[In beds >14 in. thick and under <3,000 ft of overburden; 1,160,000 short tons of coal per square mile-foot]

District

Eagle Pass. ________

Total__._. ._-__-.

Santo Tornas. ______

Total (rounded). __

San Carlos. ________

Total (rounded). __

Grand total 

(rounded) ______

County

Maverick _

Wphh

Presidio. ___

Coal bed

Unnamed__ ______

____.do-____------

Santo Tomas _ ___

San Pedro: 

upper bench __ 

lower bench. ._

Unnamed:

upper bench_ _ 

lower bench _

Thickness 

(feet)

6.0

2.0

2.0

1.5 

1.2

2.0 

2.0

Area 

(square 

miles)

18

140

40

10 

5

5 

5

Resources 

(millions of 

short tons, 

rounded)

125

400

525

90

17

7

115

12 

12

25

665
D26 CONTRIBUTIONS TO ECONOMIC GEOLOGY

shallow overburden in about 900 square miles of southern Brewster 

County, and in at least 50 square miles of northwestern Presidio 

County. If 5 percent of these areas is estimated to contain at least one 

bituminous coal bed 14 inches thick under less than 3,000 feet of overburden, a potential resource of about 62 million short tons of bituminous coal would be added to the State resources for Brewster County, 

and 3 million short tons, for Presidio County.

The total original bituminous and cannel coal resources of Texas 

are summarized in table 4.

TABLE 4. Summary of original bituminous and cannel coal resources in Texas 

[In beds >14 inches thick and under <3,000 feet of overburden; in millions of short tons, rounded]

Area

North-central Texas. _____________________

Eagle Pass district. ______________________

Santo Tomas district ___ _-__-_.___-___-_

San Carlos district ___ ____ _____________

Brewster County _ _-___-__-_______--__-_

Presidio County 1 ____-____.___________-__

Total (rounded) ___ _________________

Resources 

determined 

by mapping 

and exploration

5,400

525

115

25

None

___do.--_-

6,070

Possible additional resources in 

unexplored 

areas

___do____.

___do____.

___do_____

62

3

65

Total resources

5,400

525

115

25

62

3

6,100

1 Excluding the San Carlos district.

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BITUMINOUS COAL RESOURCES OF TEXAS D27

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D28 CONTRIBUTIONS TO ECONOMIC GEOLOGY

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