U.S. Department of the Interior

U.S. Geological Survey

USGS Fact Sheet FS-072-02

August 2002 Printed on recycled paper

Printed on recycled paper

Introduction

This assessment provides overviews of the geologic setting, distribution, quantity, and quality of the major producing coals in the 

Illinois Basin. The coal-bearing rocks of the Illinois Basin are of 

Pennsylvanian age and underlie 36,800 mi2 in Illinois, 6,500 mi2 in 

Indiana, and 6,400 mi2 in western Kentucky. The major economic coals 

in the basin are the Springfield, Herrin, Danville, and Baker Coals.

The principal products of this assessment are:

A. Coal resource estimates categorized by State, mining district, 

county, geologic reliability of the estimate, and coal thickness and depth;

B. Regional and statewide maps that depict coal extent, thickness, 

elevation (structure), mined-out areas, areas where the coal may 

potentially be mined at the surface or underground, and geographic 

distributions of ash, sulfur, and major, minor, and trace-element contents; and 

C. Digital databases that contain all publicly available pointsource data on coal thickness and depth (more than 40,000 records) 

and coal quality (more than 6,900 records). 

This assessment was a cooperative effort between the U.S. Geological Survey and the State Geological Surveys of Illinois, Indiana, 

and Kentucky.

Stratigraphy—The Pennsylvanian rocks were deposited between 

about 325 and 290 million years before present. They reach a 

maximum thickness of nearly 2,500 ft in southeastern Illinois and 

generally thin toward the north, northwest, and northeast. The Pennsylvanian rocks in the Illinois Basin are divided into the Raccoon 

Creek Group, Carbondale Formation or Group, and the McLeansboro 

Group. Figure 1 shows the relative stratigraphic positions of the 

Springfield, Herrin, Danville, and Baker Coals.

Structure—The major structural features in the Illinois Basin are 

the La Salle anticlinal belt, the DuQuoin monocline, and the Cottage 

Grove−Rough Creek fault system. These structures bound the Fairfield Basin in southeastern Illinois (fig. 2). In Illinois and Indiana, the 

major coals crop out along the margins of the basin and generally dip 

to depths of more than 1,000 ft at the center of the Fairfield Basin, 

as shown for the Springfield Coal in figure 2. In western Kentucky, 

structures affecting the coal-bearing rocks are different on either side 

of the east-west-trending Rough Creek fault system. North of the 

Rough Creek fault system, the rocks dip gently to the west at about 

15–20 ft/mi. South of the Rough Creek fault system, the structure is 

characterized by east-west-oriented synclines with much steeper dips, 

between 50 and 250 ft/mi.

Resource Assessment of the Springfield, Herrin,

Danville, and Baker Coals in the Illinois Basin

Figure 2 (above). Major structural 

features and extent and depth of the 

Springfield Coal in the Illinois Basin. 

Modified from Hatch and Affolter 

(2002, Chapter A, fig. 4).

Illinois Western Kentucky Indiana

Danville Coal (No. 7)

Herrin Coal (No. 6)

Springfield Coal

(No. 5)

Danville Coal (VII)

Herrin Coal

Springfield Coal (V)

Herrin coal (No. 11)

Springfield coal

(No. 9)

Baker coal (No. 13)

 Shelburn

Formation

 Dugger Formation Petersburg Formation Linton Formation

 Shelburn

Formation

Carbondale Formation

Carbondale Formation

Desmoinesian

Middle

PENNSYLVANIAN

Raccoon Creek Group

Carbondale Group

McLeansboro

 Group

McLeansboro

 Group

McLeansboro

 Group

Raccoon Creek Group Raccoon Creek Group

Shelburn Formation

Patoka Formation Patoka Formation Patoka Formation

Figure 1 (left). Generalized stratigraphic framework for the 

major producing coals in the Illinois Basin. Modified from 

Mastalerz and Harper (1998) and Greb and others (1992).

La

Salle

Anticlinal Bel

Fairfield t

Basin

DuQuoin

Monocline

Cottage Grove - Rough Creek Fault System

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ILLINOIS

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Major Economic Coals

Springfield Coal—The Springfield Coal is the most extensively mined coal in the Illinois Basin. In Illinois, this coal 

has a thickness of between 4.5 and 6 ft in most areas where it 

has been mined. Thickness of the Springfield Coal (in inches) is 

shown in figure 3. In Indiana, coal thickness is usually between 

3 and 7.4 ft, but as much as 13 ft has been reported. South of 

the Rough Creek fault system in western Kentucky, the coal is 

5–6 ft in thickness, but thins to less than 4 ft toward the east and 

northeast of the Rough Creek fault system.

Herrin Coal—In Illinois, the Herrin Coal averages more than 

6 ft thick over extensive areas and locally reaches 15 ft thick. 

It is thinner and irregular in thickness in much of central and 

southeastern Illinois. In Indiana, the Herrin is not well developed, and it is not mined. In western Kentucky, the Herrin occurs 

in two geographically distinct bodies. The thicker of these bodies 

is in a narrow belt along the south edge of the coal field, where 

the Herrin is as much as 10 ft thick. Throughout the basin, the 

lower part of the Herrin Coal contains a prominent claystone 

parting (the “blue band”) that normally is 1–3 in. thick. 

Danville and Baker Coals—In east-central Illinois, the Danville Coal is as much as 6 ft thick. In most of the rest of the 

State, the Danville is thin, generally from a few inches to less 

than 3 ft thick. In Indiana, the Danville ranges from 0.2 to 6 

ft thick, averaging 4 ft in the north and 2 ft in the south. In 

western Kentucky, the Baker coal is a complex, multiple-bench 

zone in which mineable coals are separated by rock partings 

(Weisenfluh and others, 1998). The Danville Coal in southern 

Indiana is correlative to an upper bench of the Baker coal in 

western Kentucky. Two distinct bodies of thicker Baker coal are 

well documented—one south of the Rough Creek fault system 

and one north.

State and basin-wide maps showing the extent, depth, and 

thickness of the Herrin, Danville, and Baker Coals can be found 

in Chapters A, C, and D, and in the Arcview project in Hatch 

and Affolter (2002).

Table 1. Estimated, remaining, identified resources of the Springfield, Herrin, Danville, and Baker Coals in Illinois, Indiana, and western Kentucky. 

[Resource numbers are rounded to two significant figures, or to nearest 100 million tons for numbers greater than 10 billion short tons. Columns may not sum exactly due to 

rounding. NC, resources not calculated. Summarized from Hatch and Affolter (2002, Chapter D, Appendixes 1-3]

Figure 3 (left). Extent and thickness of the Springfield Coal in the Illinois 

Basin. Modified from Hatch and Affolter (2002, Chapter A, fig. 7).

Remaining, identified resources (million short tons)

Springfield Coal Herrin Coal Danville and Baker Coals

Coal thickness (inches) Coal thickness (inches) Coal thickness (inches) Area

Coal

depth

(feet) 14-28 >28-42 >42 All 14-28 >28-42 >42 All 14-28 >28-42 >42 All

0–150 410 560 3,000 4,000 280 1,300 5,900 7,600 910 880 630 2,400

Illinois >150 0 11,900 45,800 57,700 0 10,500 60,900 71,400 590 7,600 7,300 15,500

Subtotal 410 12,500 48,800 61,700 280 11,800 66,800 78,900 1,500 8,500 8,000 17,900

0–150 25 280 1,800 2,100 NC NC NC NC 210 840 500 1,600

Indiana >150 150 1,500 8,400 10,100 NC NC NC NC 1,200 2,900 670 4,700

Subtotal 180 1,800 10,200 12,100 NC NC NC NC 1,400 3,700 1,200 6,300

0–150 1 17 960 980 47 74 430 550 310 360 260 930

>150 9 180 5,800 6,000 140 460 1,500 2,100 580 500 1,300 2,400

Western

Kentucky Subtotal 10 200 6,800 7,000 180 530 1,900 2,600 890 870 1,600 3,400

0–150 430 860 5,700 7,000 320 1,400 6,300 8,100 1,400 2,100 1,400 4,900

>150 160 13,500 60,000 73,700 140 11,000 62,400 73,500 2,300 11,000 9,200 22,500

Total

Illinois

Basin Total 590 14,400 65,700 80,700 460 12,400 68,700 81,600 3,700 13,100 10,600 27,400

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Coal Resource Assessment

Coal Production—Coal production in Illinois Basin began in the 

early 1800’s. From 1890 to 1998, about 5,600 million short tons 

(mst) of coal were produced from all mineable coals in Illinois, about 

2,500 mst in western Kentucky, and about 2,100 mst in Indiana. A 

maximum of about 148 mst was produced from the basin in 1984. In 

2000, coal production from the Illinois Basin was about 88.4 mst.

Remaining Coal Resources—For this assessment, estimated 

remaining coal resources are categorized by coal, State, mining area, 

county, overburden thickness (0–150 ft and >150 ft), coal thickness 

(14–28 in., >28–42 in., and >42 in.), and reliability of estimate (Hatch 

and Affolter, 2002, Chapter D, Appendixes 1–3). For Illinois and 

Indiana, reliability categories are I-A (0–0.5 mi from a data point), I-B 

(>0.5–2 mi), and II-A (>2–4 mi). For western Kentucky, the categories 

are measured (0–0.25 mi from a data point), indicated (>0.25–0.75 

mi), inferred (>0.75–3.0 mi), and hypothetical (>3 mi). The remaining 

identified resources (reliability categories I-A + I-B + II-A or measured 

+ indicated + inferred) categorized by coal, coal depth, and coal thickness for each State and for the basin are tabulated in table 1.

Resource quantities tabulated in table 1 can be summarized as 

follows:

A. For the Springfield Coal, remaining, identified resources in 

deposits >42 in. thick and at depths of 0–150 ft (potentially surface 

mineable) are about 5.7 billion short tons (bst). For depths >150 ft 

(potentially mineable by underground methods), resources are about 

60 bst. As an example, areas where the Springfield Coal is at depths of 

0–150 ft and >150 ft are shown in figure 2.

B. For the Herrin Coal, remaining, identified resources in deposits 

>42 in. thick and at depths of 0–150 ft are about 6.3 bst; for depths 

>150 ft, they are about 62.4 bst.

C. For the Danville and Baker Coals, remaining, identified 

resources in deposits >42 in. thick and at depths of 0–150 ft are about 

1.4 bst; for depths >150 ft, they are about 9.2 bst.

D. For the Springfield, Herrin, Danville, and Baker Coals, total 

remaining, identified resources in deposits >42 in. thick are estimated 

at 145 bst.

Coal Availability—Coal resources available for mining are often 

significantly less than the original coal resource because coal has 

been mined, or because the coal resource is unavailable due to landuse or technological restrictions. Examples of land-use restrictions 

include cities, national forests, major roads, or cemeteries. Examples 

of technological restrictions include areas where the coal is <42 in. 

thick, or where the interburden between beds is too thin.

Cooperative studies by the USGS and the State Geological Surveys 

show that for nineteen selected 7.5-minute quadrangles in Illinois, 46 

percent (4.6 bst) of the original coal resource (Springfield, Herrin, 

Danville, and two other coals) is available for mining. For ten 

selected 7.5-minute quadrangles in Indiana, 57 percent (3.3 bst) of the 

Table 3. Means and ranges of ash yield, calorific value, and total sulfur, arsenic, and mercury contents for the Springfield, Herrin, Danville, and Baker 

Coals in the Illinois Basin. 

[Summary data are on a whole-coal, as-received basis; ppm, parts per million; n, number of analyses. Summarized from Hatch and Affolter (2002, Chapter E, Appendixes 2 and 3]

Table 2. Summary of coal availability for nineteen 7.5-minute quadrangles 

in Illinois, ten 7.5-minute quadrangles in Indiana, and twelve 7.5-minute quadrangles in western Kentucky. 

[Resource numbers are rounded to two significant figures (modified from Hatch and 

Affolter, 2002, Chapter A, table 3]

original coal resource (Springfield, Danville, and three other coals) is 

available, and for twelve selected 7.5-minute quadrangles in western 

Kentucky, 53 percent (2.7 bst) of the original coal resource (Springfield, Herrin, Baker, and two other coals) is available (table 2).

A statewide study of the availability of the Springfield Coal in 

Illinois (Treworgy and others, 1999) demonstrated that of an original 

resource of 52 bst of coal, in deposits >42 in. thick, about 57 percent 

(30 bst) is available or conditionally available for mining. Four percent (2.2 bst) is not available because it has been mined-out, 5 percent 

(2.5 bst) is not available because of land-use restrictions, and 34 

percent (18 bst) is not available because of technological restrictions. 

Less than 1 percent (0.5 bst) of the Springfield Coal resource lies 

beneath public lands.

Coal Quality—Statistical summaries of calorific value, ash yield, 

and total sulfur, arsenic, and mercury contents for the Springfield, 

Herrin, Danville, and Baker Coals are listed in table 3. Statistical 

summaries for 14 additional coal characterization parameters and for 

36 other major, minor, and trace-element contents in these coals are 

listed in Hatch and Affolter (2002, Chapter E, Appendixes 2 and 3). 

Table 3 shows that ash yields, calorific values, total sulfur, arsenic, 

and mercury contents of these coals have similar statistics. Most 

other coal characterization parameters (such as fixed carbon, volatile 

matter, forms of sulfur and ash fusion temperatures) and elemental 

compositions (such as nitrogen, lead, uranium, antimony) are also 

similar for these coals. Geographic distributions and contents of 16 

coal characterization measures and element contents for each coal can 

be found in Hatch and Affolter (2002, Chapter E, Appendix 7). An 

example of these distributions, mercury contents in the Springfield 

Coal, is shown in figure 4.

Coal resources (billion short tons)

Resource Category Illinois Indiana

Western

Kentucky Total

Original 10.0 5.8 5.1 21.0

0.7 0.7 1.0 2.4

Land-use restrictions

Mined-out

0.8 0.3 0.2 1.3

Technological restrictions 3.9 1.5 1.3 6.7

Available 4.6 3.3 2.7 11.0

Coal Ash yield

(percent)

Calorific value

(Btu/pound)

Total sulfur

(percent)

Arsenic

(ppm)

Mercury

(ppm)

Mean Range Mean Range Mean Range Mean Range Mean Range

Springfield 11.2 2.8-49.7

n = 1,832

11,280 4,810-13,910

n = 1,770

3.5 0.5-19.5

n = 1,830

12 0.27–130

n = 145

0.12 <0.01–1.2

n = 123

Herrin 10.9 2.4-43.6

n = 2,542

11,170 5,770-13,420

n = 2,390

3.0 0.3-14.5

n = 2,517

 6 <0.2–140

n = 216

0.12 <0.01–0.70

n = 206

Danville and

Baker

11.9 4.4-44.2

n = 334

10,920 5,800-12,990

n = 295

2.9 0.3-9.7

n = 335

19 0.50–70

n = 39

0.11 <0.01–0.32

n = 39
Selected References 

Cady, G.H., 1935, Classification and selection of Illinois coals: 

Illinois State Geological Survey Bulletin 62, 354 p.

Cady, G.H., 1952, Mineable coal reserves of Illinois: Illinois State 

Geological Survey Bulletin 78, 138 p.

Currens, J.C., 1986, Coal-quality data for the western Kentucky 

coal field: Kentucky Geological Survey Open-File Report, 

Series XI, 40 p.

Gluskoter, H.J., Ruch, R.R., Miller, W.G., Cahill, R.A., Dreher, 

G.B., and Kuhn, J.K., 1977, Trace elements in coal—

Occurrences and distribution: Illinois State Geological Survey 

Circular 499, 154 p.

Greb, S.F., Williams, D.A., and Williamson, A.D., 1992, Geology 

and stratigraphy of the western Kentucky coal field: Kentucky 

Geological Survey Bulletin 1, Series XI, 77 p.

Hasenmueller, W.A., 1994, The quality of Indiana’s coal resources: 

Indiana Geological Survey Occasional Paper 63, 45 p.

Hatch, J.R., and Affolter, R.H., eds., 2002, Resource assessment of 

the Springfield, Herrin, Danville, and Baker Coals in the Illinois 

Basin: U.S. Geological Survey Professional Paper 1625-D, 2 CD 

ROMs (Chapters A-E and Interactive ArcView project).

Mastalerz, M.D., and Harper, Denver, 1998, Coal in Indiana—A 

geologic overview: Indiana Geological Survey Special Report 

60, 45 p.

Spencer, F.D., 1953, Coal resources of Indiana: U.S. Geological 

Survey Circular 266, 42 p.

Smith, G.E., and Brant, R.A., 1980, Western Kentucky coal 

resources: Lexington, Ky., University of Kentucky Institute for 

Mining and Minerals Research, Energy Resource Series, 148 p.

Treworgy, C.G., Korose, C.P., Chenowith, C.A., and North, D.L., 

1999, Availability of the Springfield Coal for mining in Illinois: 

Illinois State Geological Survey Illinois Mineral Note 118, 43 p.

Weisenfluh, G.A., Andrews, W.A., and Hiett, K.K., 1998, 

Availability of coal resources for the development of coal–

Western Kentucky summary report: Kentucky Geological 

Survey Interim Report for U.S. Department of Interior Grant 

14-08-001-A0896, 32 p.

For further information on Illinois Basin coal resources 

contact:

Joe Hatch, U.S. Geological Survey

Phone: 303-236-5418; jrhatch@usgs.gov

Russ Jacobson, Illinois State Geological Survey

Phone: 217-244-2426; jacobson@isgs.uiuc.edu

Maria Mastalerz, Indiana Geological Survey

Phone: 812-855-9416; mmastale@indiana.edu

William Andrews, Kentucky Geological Survey

Phone: 859-257-5500; wandrews@kgs.mm.uky.edu

Or

Jerry Weisenfluh, Kentucky Geological Survey

Phone: 859-257-5500; jerryw@kgs.mm.uky.edu

Figure 4. Extent of the Springfield Coal in the Illinois Basin, localities of coal samples, 

and mercury contents (whole-coal basis). Modified from Hatch and Affolter (2002, Chapter 

E, Appendix 7, fig. 44).

For further information on coal quality, contact:

Ron Affolter, U.S. Geological Survey

Phone: 303-236-7752; affolter@usgs.gov

For further information on GIS products, contact:

Greg Gunther, U.S. Geological Survey

Phone: 303-236-5884; ggunther@usgs.gov

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