Introduction

Coal has been mined actively and

extensively in the Appalachian coal

region (fig. 1) since the mid-1800’s. In

some areas, production from major coal

beds began to decline as early as 1907.

Nevertheless, 40 percent of U.S. coal

production still comes from the States of

Ohio, Pennsylvania, West Virginia,

Virginia, Maryland, eastern Kentucky,

and Tennessee. These States contain six

of the top coal-producing beds in the

Appalachian basin—the Pittsburgh,

Upper Freeport, and Lower Kittanning

coal beds in the northern Appalachian

coal region and the Pond Creek, Fire

Clay, and Pocahontas No. 3 in the central

Appalachian coal region.

Even though many of these coal

beds are still being mined at top production levels, information on the distribution and quality of remaining coal

in the northern and central Appalachians is obsolete; in some areas, the last

detailed maps of the coal beds were

made nearly 90 years ago. To respond

to present needs, including clean air

standards and growing concern about

potential hazardous pollutants in coal,

we need up-to-date information on the

amount of remaining coal, its quality,

and its distribution. 

The U.S. Geological Survey

(USGS) National Coal Resource Assessment is assessing the Nation’s top-producing coal beds and zones. The program, to be completed in 2000, will provide digital assessments of the quality

and quantity of the top producing coals

throughout the United States. In the

northern and central Appalachians, the

focus is on the six coal beds mentioned

above. The assessment is being achieved

through close partnerships with the State

Geological Surveys of Ohio, Pennsylvania, West Virginia, Virginia, Maryland,

Kentucky, and Tennessee. These States

enter new data and data from published

records that reside in the State archives

into the National Coal Resource Data

System (NCRDS). State data form the

foundation of the assessment in the

Appalachian coal region, and State participation is funded through the USGS

State Cooperative project.

Assessment Products

Earlier in the century, it was sufficient to know the location of coal beds,

their thickness, rank, coking characteristics, and how they could best be mined.

Today, a much broader range of information is necessary to evaluate coal

resources, including data on sulfur content, ash yield, and potential hazardous

pollutants. The National Coal Resource

Assessment is designed to compile and

integrate the available information, store

it in a form that is easily accessible and

readily updated, and summarize it in a

variety of useful products based on geographical information systems (GIS)

(see figs. 2–7). The national assessment

thus provides both an up-to- date view

of the Nation’s coal resources and an

ongoing archive of coal information

available for public use.

The primary products of the assessment of the northern and central

Appalachians will be digital databases

of detailed information on the six major

producing coal beds. This information

will be made available on a CD-ROM

containing stratigraphic and geochemical databases of all nonproprietary

information used in the assessment. In

addition to basic data for each coal bed,

the CD-ROM will provide estimates of

original and remaining resources and a

variety of maps, cross sections, and

graphs (see the section entitled “The

Pittsburgh Coal Bed—An Example

Assessment”). 

(Continued on back page)

Coal Resource Assessments in the Northern

and Central Appalachian Coal Region

U.S. Department of the Interior

U.S. Geological Survey

USGS Fact Sheet FS–115–99

October 1999

200 mi

200 km

Low-volatile bituminous coal

Medium- and high-volatile

bituminous coal

EXPLANATION

OH

PA

MD

TN

NC

KY

GA

AL

VA

SC

WV

Figure 1. The Appalachian

basin coal region. The

USGS assessment is

focused in the northern

and central parts of the

Appalachian coal region

(Kentucky, West Virginia,

Virginia, Maryland, Pennsylvania, and Ohio)

because about 93 percent 

of Appalachian coal is 

produced here.
The Pittsburgh Coal Bed—

An Example Assessment

The Pittsburgh coal bed (fig. 2), the

top producer in the northern Appalachian region and the second largest producer in the Nation, is the first of the six

coal beds in the northern and central

Appalachian basin coal region to undergo full digital assessment. We are presenting data for the Pittsburgh coal bed

as an example of the type of information

that is being compiled during the assessment of coal resources in the Appalachian basin.

The stratigraphic database contains

more than 5,000 descriptions from drill

cores, mine locations, and outcrops,

with an additional 2,000 records that

contain data on coal elevation. The geochemical database consists of about

3,400 analyses of ash yield, sulfur content, and calorific value and about 160

analyses of selected major, minor, and

trace elements. In addition, more than

100 paper maps at scales ranging from

1:24,000 to 1:250,000 were digitized to

create a single GIS coverage of the

extent of the coal bed.

For each of the subject coal beds, a

number of maps will summarize the

information contained in the databases.

The CD-ROM will provide maps of total

extent and mined area (fig. 2), structure

contour (or coal bed elevation) (fig. 3),

overburden thickness (the material that

Figure 2. Extent of the Pittsburgh coal bed and its stratigraphically equivalent horizon (which is represented by thin or absent

coal or insufficient data), areas of known mining, and areas

that contain resources that are not presently mined. From Ruppert, Tewalt, and Bragg, 1997.

Figure 3. Top of the Pittsburgh coal bed. The structure contour interval is 50 feet. From Tewalt, Ruppert, Bragg, Carlton,

Brezinski, Yarnell, and Wallack, 1997, sheet 1.

Figure 4. Overburden thickness or the thickness of the rock

and soil that lie above the Pittsburgh coal bed. The thickness

was derived by subtracting the elevation of the Pittsburgh coal

bed from digital models that represent surface elevation. Overburden thickness categories are defined by mining practices

and USGS coal resource methodology. From Tewalt, Ruppert,

Bragg, Carlton, Brezinski, Yarnell, and Wallack, 1997, sheet 2.

Figure 5. Thickness of the Pittsburgh coal bed, as represented

by isopach lines or thickness contours, generalized to remove

local variations. Thickness contours are presented at 2-foot

intervals. From Tewalt, Ruppert, Bragg, Carlton, Brezinski, 

and Wallack, 1997.
overlies the coal) (fig. 4), and coal bed

thickness (fig. 5). Table 1 presents mean

ash yield, sulfur content, and calorific

value (on an as-received basis) by State.

In addition to these maps and charts, the

CD-ROM will provide summary geologic cross sections, stratigraphic columns

(fig. 6), and point-and-click maps that

will allow the user to easily retrieve data

for specific map localities. Resource

information will also be available by

State and county. In addition to the CDROM, the material compiled for each of

the six major producing beds will be

available on the World Wide Web.

The Pittsburgh coal bed data also

allow estimation of the amount of original resource and the tonnage that

remains. The results of this analysis are

summarized by State in figure 7. Of an

original 34 billion short tons, 16 billion

short tons of resource remain. The data

also clearly indicate that the best of the

remaining resource is in southwestern

Pennsylvania and adjacent areas of West

Virginia (fig. 2), where blocks of medium ash (>8 to <15 weight percent) and

medium sulfur (>1 to <3 weight percent) coal remain.

The remaining available, recoverable

resource is less than 16 billion short tons.

Various constraints on mining, including

Federal and State mining regulations,

land use and environmental regulations

and concerns, geologic and technical factors, and economic realities limit the

amount of the coal resource that is actually available for production. Studies

completed in various regions within the

eastern coal fields indicate that the recoverable resources may be as small as 4

percent of the original in-place amount.

B

Figure 7. Original and remaining resources of the Pittsburgh coal bed in Maryland, Ohio, Pennsylvania, and

West Virginia.

[Min = minimum; Max = maximum; Std. Dev. = standard

deviation; No. Spls. = number of samples]

Pennsylvanian

Monongahela

System

Dunkard Conemaugh

Permian

Thickness

in feet

Series Lower Permian Upper Pennsylvanian

Generalized

 Lithologies

Pittsburgh coal bed

Redstone coal bed

Fishpot coal bed

Sewickley coal bed

Uniontown coal bed

Little Waynesburg coal bed

Waynesburg coal bed

40 ± 240-430 40 ±

Group/

Formation

 Names of Selected 

 Units

(lowermost part) (uppermost part)

Benwood Limestone

Sandstone in the lower part

of the Pittsburgh Formation

(?)

Sandstone

Limestone

Shale &

Siltstone

Shale

Claystone

Coal

Fireclay

Siltstone

Coal, Coal

& Shale

No Record

EXPLANATION

Table 1. State averages of ash yield (percent), sulfur content (percent),

and calorific value (British thermal units per pound) for the Pittsburgh

coal bed on an as-received basis.

Figure 6. Generalized stratigraphic column of the Upper

Pennsylvanian Monongahela

Group. The Pittsburgh coal

bed divides the Monongahela

Group from the underlying

Conemaugh Group strata in

the Appalachian basin. From

Tewalt, Ruppert, Bragg, Carlton, Brezinski, and Wallack,

1997.

Min

Max 

Mean

Std. Dev.

No. Spls.

Min

Max 

Mean

Std. Dev.

No. Spls.

Min

Max 

Mean

Std. Dev.

No. Spls.

Min

Max 

Mean

Std. Dev.

No. Spls.

Min

Max 

Mean

Std. Dev.

No. Spls.

Pennsylvania

Maryland

West Virginia

Ohio

All

 5.7

 13.62

 7.44

 1.61

 33 

 1.85

 29.72

 9.9

 3.9

 578

 3.9

 33.2

 8.45

 2.36

1,968

 3.5

 24.1

 9.97

 2.91

 694

 1.85

 33.2

 9.02

 2.9

3,273

 .7

 1.16

 .87

 .1

 32 

 .47

 5.4

 1.89

 .93

 564

 .4

 6.75

 2.81

 1.01

1,964

 .6

 6.41

 3.48

 1.04

 788

 .4

 6.75

 2.8

 1.13

3,348

12,870

14,480

14,020

 420

 21

10,780

14,400

13,170

 650

 503

11,190

14,780

13,410

 430

 1,689

10,670

13,740

12,380

 610

 685

10,670

14,780

13,130

 680

 2,898

State Ash

yield

Sulfur

content

Calorific

value
(Continued from front page)

The CD-ROM will thus be a

resource that provides a detailed, threedimensional picture of the form and

character of each of the assessed coal

beds and the non-coal-bearing strata or

“horizons” that are laterally continuous

with them. When combined with coal

quality data (ash yield, sulfur content,

trace elements), a remarkably detailed

picture of the resource emerges. With

GIS technology, this detail can be presented in a variety of ways to satisfy

diverse needs.

Sources of Information

The primary sources of information

for the assessment of coals in the northern and central Appalachian basin are

two types of databases and an extensive

archive of existing maps for each

assessed coal bed.

1. Stratigraphic databases.—The stratigraphic databases contain descriptive

information on coal beds compiled from

tens of thousands of drill cores, surface

outcrops, and mine and coal elevation

records. Much of this information is

stored in the NCRDS. Virtually all the

records available contain data on coal

bed thickness; many also include information on the occurrence of rock partings within the coal.

2. Geochemical databases.—The geochemical databases include data generated

by the USGS, the former U.S. Bureau of

Mines, The Pennsylvania State University, Federal and State agencies, and other

published analyses. The databases consist

of about 8,000 records containing ash

yield, sulfur content, and gross calorific

value for all samples and major-, minor-,

and trace-element analyses (including

antimony, arsenic, beryllium, cadmium,

chromium, cobalt, lead, manganese, mercury, nickel, selenium, and uranium,

depending on availability of information)

for about 1,000 samples.

3. Map archive.—The map archive consists of more than 400 paper maps that the

USGS has collected and digitized to establish the extent of coal beds and a variety of

other records and sources that show the

extent of areas already mined, both surface

and subsurface. The maps are from the

USGS, State Geological Surveys, commercial firms, and other published sources. 

Other Uses

Coal resource information is useful

for resource planning and development,

and it has a number of other applications. Much of the coal in the Appalachian basin coal region has already been

mined because it is high in calorific

value and is easily removed. Remaining

coals are generally higher in ash yield

and sulfur content, stratigraphically

deeper, and therefore, more expensive to

mine. Many Appalachian coal mines

have already closed, and others will be

shutting down over the next couple of

decades as they are mined-out and as

new clean air standards are established.

Appalachian coals are sometimes

replaced by lower sulfur, economically

competitive coals from the Western United States. These changes may cause

severe economic disruption in communities that have been supported historically

by coal. By using the assessment databases, it will be possible to identify these

communities before the full effects of

mine closings occur.

Maps can also be used as regional

guides to pinpoint areas that may be vulnerable to other problems such as acid

mine drainage. In the case of the Pittsburgh coal bed, for example, old mines

are filling with water, creating a hydrostatic head that may drive acid waters

into sensitive areas. By using the assessment areal extent, mining areas, and

structure contour databases, potential

avenues of drainage can be identified,

and mitigation efforts put in place.

References Cited

Ruppert, L.F., Tewalt, S.J., and Bragg,

L.J., 1997, Map showing areal extent

of the Pittsburgh coal bed and horizon

and mined areas of the Pittsburgh coal

bed in Pennsylvania, Ohio, West Virginia, and Maryland, digitally compiled by Tully, J.K., Pierce, J., Weller,

A., and Yarnell, J.M.: U.S. Geological

Survey Open-File Report 96–280,

scale 1:425,000. Available on the

World Wide Web at

http://energy.er.usgs.gov/products

Tewalt, S.J., Ruppert, L.F., Bragg, L.J.,

Carlton, R.W., Brezinski, D.K., and

Wallack, R.N., 1997, Map showing

generalized thickness contours of the

Pittsburgh coal bed in Pennsylvania,

Ohio, West Virginia, and Maryland,

digitally compiled by Tewalt, S.J.,

Ruppert, L.F., Wallack, R.N., and

Weiss, Eric: U.S. Geological Survey

Open-File Report 97–748, scale

1:425,000, 1 sheet. Available on the

World Wide Web at

http://energy.er.usgs.gov/products

Tewalt, S.J., Ruppert, L.F., Bragg, L.J.,

Carlton, R.W., Brezinski, D.K.,

Yarnell, J.M., and Wallack, R.N.,

1997, Map showing structure contours (sheet 1) and overburden isopleths (sheet 2) of the Pittsburgh coal

bed in Pennsylvania, Ohio, West Virginia, and Maryland, digitally compiled by Tewalt, S.J., Wallack, R.N.,

and Tully, J.K.: U.S. Geological Survey Open-File 97–864, scale

1:425,000, 2 sheets. Available on the

World Wide Web at

http://energy.er.usgs.gov/products

For more information, please contact:

Leslie (Jingle) Ruppert

U.S. Geological Survey

956 National Center 

Reston, VA 20192

Telephone: (703) 648–6431

E-mail: lruppert@usgs.gov

Printed on recycled paper