U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2010–5152

Correlation Chart of Pennsylvanian Rocks in Alabama, 

Tennessee, Kentucky, Virginia, West Virginia, Ohio, 

Maryland, and Pennsylvania Showing Approximate Position 

of Coal Beds, Coal Zones, and Key Stratigraphic Units
Correlation Chart of Pennsylvanian 

Rocks in Alabama, Tennessee, Kentucky, 

Virginia, West Virginia, Ohio, Maryland, 

and Pennsylvania Showing Approximate 

Position of Coal Beds, Coal Zones, and Key 

Stratigraphic Units

By Leslie F. Ruppert, Michael H. Trippi, and Ernie R. Slucher

Scientific Investigations Report 2010–5152

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2010

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Suggested citation:

Ruppert, L.F., Trippi, M.H., and Slucher, E.R., 2010, Correlation chart of Pennsylvanian rocks in Alabama, Tennessee, 

Kentucky, Virginia, West Virginia, Ohio, Maryland, and Pennsylvania showing approximate position of coal beds, coal 

zones, and key stratigraphic units: U.S. Geological Survey Scientific Investigations Report 2010–5152, 9 p., 3 plates, 

available only online at http://pubs.usgs.gov/sir/2010/5152/.
iii

Contents

Introduction.....................................................................................................................................................1

Geology of the Appalachian Basin and the Pennsylvania Anthracite Region ....................................2

Coal Fields of the Appalachian Basin.........................................................................................................3

Coal Production Within the Appalachian Basin...............................................................................3

Pennsylvanian Strata Within the Appalachian Basin and the Pennsylvania Anthracite Fields .......3

Lower Pennsylvanian Rocks...............................................................................................................4

Middle Pennsylvanian Rocks..............................................................................................................5

Upper Pennsylvanian Rocks ...............................................................................................................5

References Cited............................................................................................................................................5

Figures

[As separate files]

1. Chronostratigraphic correlation chart of coal-bearing Pennsylvanian rocks in the 

Appalachian basin and Pennsylvania Anthracite region showing approximate position 

of coal beds, coal zones, and key stratigraphic units.

2. Map showing the location of the Appalachian basin coal regions, the Pennsylvania 

Anthracite region, and designated coal fields.

3. Map showing the location of major structural features and the coal-bearing regions 

of the Appalachian basin, including the Black Warrior basin and the Pennsylvania 

Anthracite region.

Introduction

The Appalachian basin, one of the largest Pennsylvanian 

bituminous coal-producing regions in the world, currently 

contains nearly one-half of the top 15 coal-producing States 

in the United States (Energy Information Agency, 2006). 

Anthracite of Pennsylvanian age occurs in synclinal basins in 

eastern Pennsylvania, but production is minimal. A simplified 

correlation chart was compiled from published and unpublished sources as a means of visualizing currently accepted 

stratigraphic relations between the rock formations, coal beds, 

coal zones, and key stratigraphic units in Alabama, Tennessee, Kentucky, Virginia, West Virginia, Ohio, Maryland, and 

Pennsylvania. The thickness of each column is based on 

chronostratigraphic divisions (Lower, Middle, and Upper 

Pennsylvanian), not the thickness of strata. Researchers of 

Pennsylvanian strata in the Appalachian basin also use biostratigraphic markers and other relative and absolute geologic 

age associations between the rocks to better understand the 

spatial relations of the strata. Thus, the stratigraphic correlation data in this chart should be considered provisional and 

will be updated as coal-bearing rocks within the Appalachian 

coal regions continue to be evaluated.

Most geologic formations are identified and defined 

by the distinctive lithologic features they contain. However, 

formations of Pennsylvanian age in the Appalachian basin and 

the Pennsylvania Anthracite region have traditionally been 

described and named to reflect the presence or absence of 

economic coal beds and coarse-grained sandstone units, most 

of which have since been proven to be locally or regionally 

discontinuous (Ruppert and Rice, 2001). Many of the stratigraphic names and boundaries used for the coals and other 

geologic units in the Pennsylvanian rocks differ between 

States or regions (fig. 1). Because local and regional stratigraphic complexities occur within some States, a multiplicity 

of State-specific names are introduced that may be confusing to those conducting regional geologic assessments in the 

basin.

Nonetheless, many of these stratigraphic names and 

boundaries have some elements that allow for regional stratigraphic correlation. For instance, many coals in the northern Appalachian coal region are easier to trace over greater 

distances than coals in the central and southern Appalachian 

coal regions (fig. 2). The Upper Pennsylvanian Pittsburgh 

coal bed (fig. 1) of the northern Appalachian coal region, 

for example, occurs as a synchronogenic bed deposited on 

a laterally continuous surface of sediments (Cross, 1954; 

Tewalt and others, 2001). The base of the Pittsburgh coal bed 

is designated as the contact between the Conemaugh Group 

(Upper Pennsylvanian) and the overlying Monongahela Group 

in western Pennsylvania, western Maryland, Ohio, and West 

Virginia (fig. 1). Therefore, in areas where the Pittsburgh coal 

bed is present, there is little controversy over its position or 

the placement of the boundary between the Conemaugh and 

Monongahela Groups.

In other regions of the basin, group and formation 

boundaries are more difficult to identify over extensive areas. 

One example is the placement of the contact between the New 

River Formation and the overlying Kanawha Formation—a 

boundary that is not easily defined beyond the area where 

these units were first defined in West Virginia. At the type 

section of the Kanawha Formation, the base of the Lower 

Douglas coal zone (fig. 1) defines the contact between the 

Kanawha Formation and the underlying New River Formation 

(Rice and others, 1994b). However, subsequent mapping has 

demonstrated that the Lower Douglas coal zone is regionally 

discontinuous and in many parts of West Virginia is absent 

(Blake and others, 2002). Where absent, the Nuttall Sandstone 

Correlation Chart of Pennsylvanian Rocks in Alabama, 

Tennessee, Kentucky, Virginia, West Virginia, Ohio, 

Maryland, and Pennsylvania Showing Approximate 

Position of Coal Beds, Coal Zones, and Key Stratigraphic 

Units

By Leslie F. Ruppert,1 Michael H. Trippi,1 and Ernie R. Slucher2

 1U.S. Geological Survey, Reston, Va.

 2Ohio Division of Geological Survey, Columbus, Ohio (retired).
2 Correlation Chart of Pennsylvanian Rocks in the Appalachian Basin

Member of the underlying New River Formation sometimes 

occurs in the stratigraphic position of the Lower Douglas 

coal zone. Yet even the Nuttall Sandstone Member has been 

found to be regionally discontinuous and of varying thickness 

throughout its extent, features that hinder its use as a regional 

stratigraphic marker bed in the Appalachian basin.

Because of the many names used to identify individual 

coal beds and coal zones in the historic Appalachian basin 

coal-mining districts, coal bed designations may differ even 

more than stratigraphic nomenclature. In eastern Kentucky, 

northwest of the Pine Mountain thrust fault on the Cumberland 

overthrust sheet, for example, coal beds or coal zones equivalent to the Lower Elkhorn coal zone (within the Pikeville Formation) are identified also as the Eagle coal zone, Pond Creek 

coal zone, and Blue Gem coal bed (fig. 1). Southeast of the 

Pine Mountain thrust fault, yet still in Kentucky, equivalent 

coals in this same interval are known as the Imboden and Rich 

Mountain. Moreover, this same interval of coal is identified 

as the Blue Gem coal in Tennessee, the Imboden coal bed or 

Campbell Creek or Pond Creek coal zones in Virginia, and the 

Eagle coal zone in West Virginia.

Geology of the Appalachian Basin and 

the Pennsylvania Anthracite Region

The proto-Appalachian basin first developed on Mesoproterozoic (1.1 billion years old) continental crust that 

extended along the thinned continental margin of Iapetus, the 

proto-Atlantic Ocean. During Mississippian time, the basin 

was located about 20° S. latitude, but by Pennsylvanian time 

had migrated north and was mostly in the equatorial region 

(Cecil, 1990). Between 330 and 265 million years ago, the 

Appalachian Mountains were formed by the collision of the 

southern part of Laurentia (composed of the North American 

and Greenland continental plates) and Gondwana (composed 

of the African, South American, Indian, Antarctica, Australian, 

New Guinean, and New Zealand continental plates) (Hatcher 

and others, 1989). The collision caused downwarping, or 

subsidence, west of the mountains and formed an elongated 

foreland basin (Hatcher and others, 1989). The newly created 

accommodation space within the Appalachian basin was filled 

with a wedge of clastic sediments that generally thickened 

southeastward towards the pre-thrusting axis of the basin. The 

axial region has been broken by Appalachian thrust sheets so 

that now much of the younger part of the stratigraphic section 

has been uplifted and eroded away. However, the axial region 

is inferred to have been east of, and parallel to, the eastern 

edge of the present-day Pennsylvanian outcrop belt. The western edge of the basin is marked by the Cincinnati arch (fig. 3), 

which, in part, separates the Appalachian foreland basin from 

the Eastern Interior basin of the midcontinent. It is believed 

that some Pennsylvanian sediments may have been eroded 

from the newly formed Appalachian Mountains, transported 

across the Cincinnati arch, and deposited into the Eastern 

Interior basin (Siever and Potter, 1956; Rice and Schwietering, 

1988). Presently, the eastern limit of Pennsylvanian rocks in 

the Appalachian basin is generally defined by the west- and 

northwest-facing northeast-trending Allegheny structural 

front (fig. 3), a feature that marks the boundary between the 

Appalachian Plateau and the Valley and Ridge physiographic 

provinces.

The Black Warrior basin of Alabama is also a late Paleozoic foreland basin that extends westward into the subsurface 

of Mississippi (fig. 3). This basin formed in the structural 

recess between the Appalachian and Ouachita fold and thrust 

belts (Ryder, 1987; Pashin, 2004). The southeastern edge 

of the Black Warrior coal basin is strongly deformed into a 

series of synclinal basins that delineate the western edge of 

the Appalachian fold belt (Davis and Ehrlich, 1974; Thomas, 

1988). Cretaceous and Tertiary coastal sediments of the Mississippi embayment and the Gulf Coastal Plain conceal most 

of the Pennsylvanian strata to the south and west (Thomas, 

1988). Abundant Lower Pennsylvanian coal resources of the 

Black Warrior, Cahaba, Coosa, Sand Mountain, and Lookout 

Mountain fields have historically been included within the 

Appalachian basin coal resource base as part of the southern 

Appalachian coal region (fig. 2). That traditional treatment 

continues in this paper.

The oldest preserved Pennsylvanian rocks are found in 

three areas within the Appalachian basin. They are (1) the 

deepest part of the central Appalachian coal region in southeastern West Virginia and western Virginia, near Pocahontas, 

Va.; (2) the Eastern Middle, Western Middle, and Southern 

fields of the Pennsylvania Anthracite region in eastern Pennsylvania; and (3) the Black Warrior, Cahaba, and Coosa fields 

of Alabama (fig. 2). Near Pocahontas, Va., the maximum 

thickness of the Pocahontas Formation in this area exceeds 

700 feet (ft) (Englund, 1979). A pre-Pennsylvanian unconformity exists in the Black Warrior coal basin. However, in this 

region, greater subsidence preserved Lower Pennsylvanian 

sediments that exceed 5,700 ft in maximum thickness (R.E. 

Carroll, Geological Survey of Alabama, written commun., 

2006).

The youngest Pennsylvanian (and overlying Permian) 

strata are preserved in the northeast-trending Dunkard basin, 

which is found in the northern and central Appalachian coal 

regions (figs. 2 and 3). In general, Pennsylvanian-age rocks 

slowly rise in elevation away from this structural axis—in all 

directions—and crop out at the surface around the perimeter of 

the Appalachian basin (Ruppert and Rice, 2001, and references 

contained therein).

Sediments of Pennsylvanian age were deposited in many 

types of aqueous environments that range from piedmont and 

limnic settings to coastal settings containing deltaic channels, 

marshes, peat-forming swamps, lagoons, and shallow-marine 

embayments (Ferm and Horne, 1979; Donaldson and others, 

1985; Englund and others, 1986; Slucher and Rice, 1994; 

Greb and others, 2004). During the Pennsylvanian, sediments 

derived from the newly formed Appalachian Mountains, and 

the Canadian craton to the north, prograded west, northwest, 
Pennsylvanian Strata Within the Appalachian Basin and the Pennsylvania Anthracite Fields 3

and south as fluvial channels and deltaic fans across a broad 

coastal plain. Periodically, especially during the Middle 

and lower Upper Pennsylvanian, shallow-marine incursions 

inundated the coastal environments. The occurrences of 

these marine incursions may have been partly controlled by 

the waxing and waning of continental-scale glaciation in the 

southern hemisphere (Ruppert and Rice, 2001, and references 

contained therein), repetitive processes that affected eustatic 

levels worldwide.

Coal Fields of the Appalachian Basin

The Appalachian basin has informally been subdivided 

into three coal regions—the northern, central, and southern 

Appalachian coal regions—on the basis of characteristics of 

the sediments and the coals that are found there (fig. 2). The 

three coal regions contain both formal and informal coal fields.

Two types of coal fields occur in the northern Appalachian coal region (fig. 2): bituminous-rank fields and 

anthracite-rank fields. Bituminous-rank fields include the 

Main Bituminous field, the North Central field, the Broad Top 

field, the Upper Potomac field (which includes the Lower and 

Upper Youghiogheny basins and the Castleman and Georges 

Creek basins), and the Northern West Virginia Coal Field. The 

coal-bearing region in Ohio is not subdivided into named coal 

fields or regions (fig. 2). Anthracite fields include the Western 

Northern field, the Southern and Northern fields, and the Eastern Middle and Western Middle fields. These named anthracite 

coal fields occur only in the Valley and Ridge physiographic 

province but have historically been placed in the resource base 

of the northern Appalachian coal region.

The central Appalachian coal region coal fields include 

the Southern West Virginia Coal Field, the Southwest Virginia 

Coal Field, the Eastern Kentucky Coal Field, and the Northern 

Tennessee Coal Field (fig. 2). Coal rank is generally mediumand high-volatile bituminous throughout the central region 

except in the southeastern part of the Southern West Virginia 

Coal Field (fig. 2), where coal rank is low-volatile bituminous.

 Coal fields of the southern Appalachian coal region 

include the Southern Tennessee Coal Field and the Black Warrior field of Alabama. Coal rank is medium- and high-volatile 

bituminous in both coal fields (fig. 2). Four small coal fields 

occur east of the Black Warrior field, the Sand Mountain, 

Lookout Mountain, Cahaba, and Coosa fields of Alabama.

Coal Production Within the Appalachian Basin

Pennsylvanian coal in the Appalachian basin has been 

mined nearly continuously since the 18th century and was 

a major factor in the economic development and industrial 

growth of the Eastern United States. Over 36.3 billion short 

tons (BST) of coal have been mined in the basin over the last 

215 years (see Tewalt and Ruppert, in press). The northern 

Appalachian coal region (fig. 2) is the largest historic producer 

(19.6 BST), followed by the central Appalachian coal region 

(16.7 BST), and the southern Appalachian coal region (1.9 

BST) (Tewalt and Ruppert, in press). Although the northern 

Appalachian coal region is the overall largest producer of coal 

within the basin, coal production in the central Appalachian 

coal region has outpaced that of the northern region over the 

last three decades because of the increased demand for lowsulfur coal. See Milici (1999) for a more detailed discussion of 

coal production within the basin.

Pennsylvanian Strata Within 

the Appalachian Basin and the 

Pennsylvania Anthracite Fields

Placement of the boundaries between Upper, Middle, and 

Lower Pennsylvanian rocks in the Appalachian basin tends to 

differ between States of the region because of various historic 

lithostratigraphic and historic economic subdivisions used 

to define coal-bearing intervals. For example, the boundary 

between Middle and Upper Pennsylvanian rocks is traditionally placed at the top of the Upper Freeport coal bed of the 

Allegheny Formation (Bradley, 1956). This usage coincides 

with the long-standing placement of the contact between the 

Allegheny Formation and the overlying Conemaugh Group 

at the top of the Upper Freeport coal bed. In areas where the 

Upper Freeport coal bed is absent, the boundary between the 

Allegheny Formation and the Conemaugh Group is defined by 

a gradual change in the lithologic character of the rocks. Strata 

below the Upper Freeport coal bed consist, in general, of rocks 

that are mostly shades of gray and black in color, whereas 

rocks above the Upper Freeport coal bed commonly contain 

intervals of red and green mudstone, shale, and siltstone.

However, Phillips and Peppers (1984) discovered that the 

placement of this boundary was unsubstantiated by biostratigraphic criteria. They found that both the Upper Freeport and 

overlying Mahoning coal beds of the lower Conemaugh Group 

(see figure 1) are dominated by the presence of Lycospora, an 

important Lower and Middle Pennsylvanian palynomorph. 

Furthermore, the Brush Creek coal bed, the next persistent 

coal bed above the Mahoning coal bed in the lower Conemaugh Group of Ohio, Pennsylvania, and Maryland, rarely 

contains this palynomorph (abundance < 2 percent) (Phillips 

and Peppers, 1984). Hence, on the basis of their analysis, the 

traditional stratigraphically based placement of the MiddleUpper Pennsylvanian boundary at the top of the Upper 

Freeport coal bed is untenable. Rather, the lower part of the 

overlying Conemaugh Group is clearly Middle Pennsylvanian 

in age, and the boundary between Middle and Upper Pennsylvanian rocks occurs just above the Mahoning coal bed in the 

lower part of the Conemaugh Group (see Blake and others, 

2002, and figure 1 of this report). In this report, we use the 

divisions of Blake and others (2002) for the Lower and Middle 

Pennsylvanian boundary.
4 Correlation Chart of Pennsylvanian Rocks in the Appalachian Basin

The boundary between the top of Upper Pennsylvanian 

sediments and the base of the overlying Permian sediments 

has generally been placed in the lower part of the Dunkard 

Group, at the base of the Washington coal or, where it is 

absent, the stratigraphic position of the Washington coal. This 

has traditionally been supported by the occurrence of the fossil plant Callipteris (Autunia) conferta, a diagnostic Permian 

seed fern in the seat rock of this coal bed (see Berryhill, 1963; 

Ruppert and Rice, 2001, and references contained within). 

However, spores found in coal beds in this interval only support a Late, but not latest, Pennsylvanian age (Clendening, 

1974, 1975). Blake and others (2002) concluded that earlier 

workers (Berryhill, 1963; Havlena, 1975) may have placed 

unwarranted emphasis on first occurrences of extrabasinal 

forms such as Callipteris (Autunia) conferta now known to 

have been contemporaneous with, and sporadically occupying 

specific paleoenvironments within, typical Dunkard lowland 

flora settings in the Appalachian region. The PennsylvanianPermian transition in the Appalachian basin was a period 

of tectonically induced climatic change produced by the 

newly formed Appalachian Mountains during the Alleghany 

orogeny; thus, occurrences of these highly climate-sensitive 

extrabasinal plant fossils are suspect. It is believed further age 

refinement will be possible if specific types of marine fossils 

can be identified within Dunkard rocks. Yet, to date, the only 

known marine or marginal marine fossils found in Dunkard 

strata are those with only limited biostratigraphical usefulness 

(Lingula, for example); thus, the exact age of the Dunkard 

Group cannot be refined beyond a Pennsylvanian-Permian 

age assignment (Martin, 1998; B.M. Blake, Jr., West Virginia 

Geologic and Economic Survey, oral commun., 2005).

Lower Pennsylvanian Rocks

Lower Pennsylvanian strata extend, in general, across 

the Appalachian basin as northwestward prograding, timetransgressive sequences with a depositional strike parallel to 

the Appalachian Mountains. The pre-Pennsylvanian unconformity that developed on Mississippian rocks in most regions of 

the basin formed an irregular surface, particularly along the 

western basin margins where deeply incised valleys developed 

in Mississippian rocks and controlled sedimentation patterns 

well into Middle Pennsylvanian time (Slucher and Rice, 

1994). Many of these valleys are filled with hundreds of feet 

of Pennsylvanian-age coarse-grained clastic sediments —for 

example, the Livingston Conglomerate Member of Kentucky 

and the “Sharon” Conglomerate of southern Ohio. The contact between these Pennsylvanian sediments and underlying 

Mississippian rocks is clearly erosional in most places in the 

basin.

The Pocahontas Formation consists mostly of coal-bearing sequences of carbonaceous shale and siltstone with minor 

sandstone and does not extend into the more distal parts of the 

basin beyond the Pocahontas area of Virginia (Englund, 1979). 

Northwest of Pocahontas, Va., Lower Pennsylvanian rocks in 

the central Appalachian coal region typically consist of thick 

sequences of conglomeratic quartzose sandstones that overlie 

units equivalent mostly to the upper part of the Pocahontas 

Formation (Greb and others, 2004). These younger strata 

reach a maximum thickness of more than 1,600 ft along the 

border between Virginia and Kentucky (Englund and others, 

1979; Rice and others, 1979). Included in this interval of thick 

quartzose sandstones are the New River, Lee, and Norton 

Formations and the lower part of the Wise Formation in southwestern Virginia; the New River Formation and the lower part 

of the Kanawha Formation in West Virginia; the lower part 

of the Breathitt Group—Bottom Creek Formation, Sewanee 

Sandstone, Alvy Creek Formation, Bee Rock Sandstone, and 

Grundy Formation—in eastern and southeastern Kentucky; 

and the uppermost part of the Gizzard Group, Crab Orchard 

Mountains Group, and Crooked Fork Group, and the lowermost part of the Slatestone Formation in Tennessee (fig. 1). 

In Alabama, Lower Pennsylvanian strata are subdivided into 

the Lower and Upper Pottsville Formations (fig. 1). Lower 

Pennsylvanian strata of Alabama and Tennessee reach maximum thicknesses of 5,700 ft and 2,500 ft, respectively (Luther, 

1959; Pashin and Raymond, 2005).

In the northern and westernmost areas of the bituminous 

coal fields of the northern Appalachian coal region (fig. 2), 

most Lower Pennsylvanian strata, particularly those parts 

equivalent to the Pocahontas Formation, appear to have never 

been deposited. Sediments of this age do exist, however, in 

parts of the Southern, Western Middle, and Eastern Middle 

fields in the Pennsylvania Anthracite region of eastern Pennsylvania, and in southeastern Ohio, West Virginia, Maryland, 

and the Broad Top field in Pennsylvania.

In the Pennsylvania Anthracite region, the MississippianPennsylvanian boundary is gradational as mostly red, finegrained clastics of the Upper Mississippian Mauch Chunk 

Formation intertonguing with and grading upward into gray, 

conglomeratic clastic sediments typical of the Pennsylvanian 

Pottsville Formation (Wood and others, 1986; Edmunds, 1996; 

Brezinski, 1999). Lower Pennsylvanian Pottsville strata in the 

northern Appalachian coal region reach a maximum thickness 

of about 1,500 ft in the Southern field of the Pennsylvania 

Anthracite region (Wood and others, 1986).

In Ohio, Pennsylvania, and Maryland, the separation 

between Lower and Middle Pennsylvanian rocks is problematic because of the time-transgressive nature of the Pennsylvanian sediments deposited on the eroded Mississippian surface. 

For instance, traditionally the “Sharon” coal of Ohio and 

Pennsylvania is considered the first coal above the Mississippian-Pennsylvanian boundary (fig. 1). In Ohio, the Sharon 

occurs in two widely separated areas; northeastern Ohio, in 

the vicinity of Sharon, Pa. (type section), and southern Ohio, 

near the city of Jackson (fig. 2). Although these deposits 

have long been assumed to be synchronous, palynological 

and lithostratigraphic data indicate otherwise (Bebel, 1982; 

Kosanke, 1984; C.F. Eble, Kentucky Geological Survey, written commun., 1999; Eble, 2002). These workers conclude that 

the “type” Sharon can best be correlated with lower Middle 
References Cited 5

Pennsylvanian coal beds or coal zones (for example, the Pond 

Creek to Upper Elkhorn No. 3 interval in eastern Kentucky). 

Yet the “Sharon” at Jackson, Ohio, is more likely equivalent to 

a Lower Pennsylvanian coal, perhaps the Fire Creek or Beckley coal zones in the New River Formation of West Virginia. A 

similar diachronous relationship between the “type” Quakertown coal bed of northeastern Ohio and western Pennsylvania 

and the southern Ohio coal identified as “Quakertown” is 

suggested as well (Eble, 2002). Until definitive ages can be 

determined, ages of and correlations between coal beds in this 

part of the Pennsylvanian section are tentative (Slucher and 

Rice, 1994).

Middle Pennsylvanian Rocks

Middle Pennsylvanian strata are present in the northern, 

central, and southern Appalachian coal regions. As mentioned 

earlier, defining the exact base of the Middle Pennsylvanian 

in parts of Ohio, Pennsylvania, and West Virginia is problematic. Middle Pennsylvanian rocks are only partially preserved 

in the Black Warrior basin in Alabama and in the Wartburg 

basin in Tennessee (fig. 3). In southwestern Virginia, southeastern Kentucky, and northeastern Tennessee, southeast of 

the Pine Mountain thrust fault, post-Pennsylvanian erosion has 

removed all of the middle and upper Middle Pennsylvanian 

(Desmoinesian) rocks. Only lower Middle Pennsylvanian 

(Atokan) rocks remain (see figure 1).

Typically, Middle Pennsylvanian rocks consist mostly of 

coal-bearing sequences of carbonaceous shale, mudstone, and 

siltstone with minor sandstone (Arndt, 1979). The rocks were 

deposited in coastal and deltaic systems and, unlike Lower 

Pennsylvanian rocks, commonly contain intervals of marine 

carbonate or shale (see figure 1). These marine intervals, particularly those in the lower Middle Pennsylvanian of eastern 

and southeastern Kentucky, southwestern Virginia, and West 

Virginia, consist mainly of coarsening-upward shale sequences 

several tens of meters thick (Rice and others, 1994b). Conversely, marine units in all but the lowest Pennsylvanian 

intervals in Kentucky, Ohio, Pennsylvania, and Maryland, are 

typically thin (~3 ft thick) and in many areas cherty (Slucher 

and Rice, 1994). Commonly, marine units of the upper Middle 

Pennsylvanian in the northern Appalachian coal region are 

mostly thin shale and limestone intervals (see figure 1). Freshwater limestone beds first occur in the interval just above the 

Lower Kittanning coal bed (fig. 1) and generally occur in the 

seat rock of coals or in paleosol intervals, particularly in the 

overlying Conemaugh, Monongahela, and Dunkard Groups. 

Cecil (1990) attributed the development of these deposits to 

continental-drift-induced climatic shifts.

Middle Pennsylvanian strata contain many valuable beds 

of coal, clay, and limestone. These rocks, which reach a maximum thickness of more than 2,000 ft in southwestern Virginia 

(Arndt, 1979; Englund and Thomas, 1991) include the Pottsville and Llewellyn Formations in east-central Pennsylvania, 

the upper part of the Pottsville Group, Allegheny Group or 

Formation (in West Virginia), and lowermost Conemaugh 

Group in western Pennsylvania, western Maryland, Ohio, 

and West Virginia; and the Wise and Harlan Formations in 

southwestern Virginia (fig. 1). Middle Pennsylvanian rocks in 

southeastern and eastern Kentucky and northeastern Tennessee include the middle and upper parts of the Breathitt Group 

(Pikeville, Hyden, Four Corners, and Princess Formations) 

and lowermost Conemaugh Formation. In east-central and 

southern Tennessee, Middle Pennsylvanian rocks include all 

but the lowest part of the Slatestone Formation, the Indian 

Bluff, Graves Gap, Redoak Mountain, Vowell Mountain, and 

Cross Mountain Formations (fig. 1).

Upper Pennsylvanian Rocks

Upper Pennsylvanian sediments include the Monongahela 

Group and all but the basal part of the Conemaugh Group in 

the northern Appalachian coal region, the upper part of the 

Llewellyn Group in the Pennsylvania Anthracite region, and 

the Conemaugh Formation in the central Appalachian coal 

region (fig. 1). Upper Pennsylvanian strata are absent in southwestern Virginia, southeastern Kentucky, all of Tennessee, and 

Alabama. The part of the Conemaugh Group included in the 

Upper Pennsylvanian is characterized by sequences of red and 

green mudstone, shale, siltstone and thin, non-economic coal 

beds. The lower part of the Upper Pennsylvanian, mainly from 

the Ames Limestone and older (fig. 1), contains many thin 

marine limestone beds and shale intervals that are particularly 

widespread in western areas of the northern Appalachian coal 

region. The lack of economic coal and overall abundance of 

“nonproductive” intervals of rocks within the group earned 

it the formerly applied name “Lower Barren Measures” 

(Wanless, 1939).

In contrast, the overlying Monongahela Group consists 

mostly of sandstone, siltstone, shale, and mudstone with some 

limestone. The Monongahela Group, formally known as the 

“Upper Productive Measures” (Wanless, 1939) contains several 

commercial coal beds, the most famous being the Pittsburgh 

coal bed (Tewalt and others, 2001). Upper Pennsylvanian strata 

within the Appalachian basin range in thickness from about 

650 ft in Ohio (Collins, 1979) to as much as 1,300 ft in West 

Virginia (Arkle and others, 1979; Edmunds and others, 1979). 

Thicker strata, as much as 1,900 ft, are observed in the Southern Anthracite field of Pennsylvania (Wood and others, 1969), 

which is located in the Valley and Ridge province.

References Cited

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