Structural and Stratigraphic Framework of the Giles 

County Area, a Part of the Appalachian Basin of 

Virginia and West Virginia

Late Paleozoic Depositional Trends in the Central 

Appalachian Basin

U.S. GEOLOGICAL SURVEY BULLETIN 1839-E, F

Structural and Stratigraphic Framework of the 

Giles County Area, a Part of the Appalachian Basin 

of Virginia and West Virginia

By ROBERT C. McDOWELL and ARTHUR P. SCHULTZ

Late Paleozoic Depositional Trends in the 

Central Appalachian Basin

By KENNETH J. ENGLUND and ROGER E. THOMAS

U.S. GEOLOGICAL SURVEY BULLETIN 1839-E, F

EVOLUTION OF SEDIMENTARY BASINS-APPALACHIAN BASIN
DEPARTMENT OF THE INTERIOR 

MANUEL LUJAN, Jr., Secretary

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director

Any use of trade, product, or firm names in this publication is for descriptive purposes 

only and does not imply endorsement by the U.S. Government

UNITED STATES GOVERNMENT PRINTING OFFICE: 1990

For sale by the

Books and Open-File Reports Section

U.S. Geological Survey

Federal Center, Box 25425

Denver, CO 80225

Library of Congress Cataloging in Publication Data

(Revised for ch. E, F)

Evolution of sedimentary basins Appalachian basin.

(U.S. Geological Survey bulletin ; 1839 A- )

Includes bibliographies.

Supt. of Docs, no.: I 19.3:1839A-D

Contents: ch. A. Horses and fensters of the Pulaski thrust sheet, southwestern 

Virginia/ by Arthur P. Schultz [etc.] ch. E. Structural and stratigraphic 

framework of the Giles County area, a part of the Appalachian basin of 

Virginia and West Virginia / by Robert C. McDowell and Arthur P. 

Schultz ch. F. Late Paleozoic depositional trends in the central Appalachian basin / by Kenneth J, Englund and Roger E. Thomas. 1. GeologyAppalachian basin. I. Series.

QE75.B9no. 1839 A-D 557.3 s [557.4] 88-600224 [QE78.3]
Chapter E

Structural and Stratigraphic Framework of the Giles 

County Area, a Part of the Appalachian Basin of 

Virginia and West Virginia

By ROBERT C. McDOWELL and ARTHUR P. SCHULTZ

A description of the bedrock geology of a part of the 

Appalachian foreland

U.S. GEOLOGICAL SURVEY BULLETIN 1839 

EVOLUTION OF SEDIMENTARY BASINS-APPALACHIAN BASIN

CONTENTS

Abstract El 

Introduction El 

Stratigraphy E2

Cambrian System E2

Rome Formation (Lower Cambrian) E2

Honaker Dolomite (Middle and Upper Cambrian) E3

Nolichucky Shale (Upper Cambrian) E4 

Cambrian and Ordovician Systems E4 

Ordovician System E8

Middle Ordovician limestones E8

Martinsburg Formation E8

Juniata Formation E9 

Silurian System E9

Tuscarora Quartzite E9

Rose Hill Formation E9

Keefer Sandstone E9

Tonoloway Limestone E10 

Devonian System E10

Rocky Gap Sandstone E10

Huntersville Chert E10

Millboro Shale E10

Brallier Shale Ell

Chemung Formation Ell 

Mississippian System Ell

Price Formation Ell

Maccrady Shale Ell

Greenbrier Limestone E12

Mauch Chunk Group E12

Bluefield Formation E12

Hinton Formation E12

Princeton Sandstone E13

Bluestone Formation E13 

Structural Geology and Seismicity E13 

Structural Setting E13 

Regional Structures E13 

Tectonic Evolution E17 

Seismicity E18 

Mineral Resources E19 

Iron E19 

Manganese E19 

Nonmetallic Resources E19 

Fossil Fuels E19 

Geologic Hazards E20 

References Cited E20

Contents III
PLATE

1. Geologic map of Giles County, Virginia, and adjacent areas in Virginia and West 

Virginia [In pocket]

FIGURES

1-4. Maps showing:

1. Structural provinces of the Appalachians of Virginia and West Virginia E2

2. Regional structural setting of the Giles County area of Virginia and West 

Virginia E3

3. Index to previous mapping in the Giles County area of Virginia and West 

Virginia E4

4. Index to l:24,000-scale quadrangles in the Giles County area of Virginia 

and West Virginia E4

5. Generalized columnar section for rocks in the Giles County area of Virginia and 

West Virginia E5

6. Map showing major structural features in the Giles County area of Virginia and 

West Virginia E14

7. Diagrams showing interpretation of structures along line of section A-A'(pl. 1) 

by various authors E15

TABLE

1. Stratigraphic nomenclature used in this study and other studies in the Giles County 

area of Virginia and West Virginia E6

CONVERSION FACTORS FOR SOME SI METRIC AND U.S. UNITS OF MEASURE

To convert from To Multiply by

Feet (ft) Meters (m) 0.3048

Miles (mi) Kilometers (km) 1.609

Pounds (Ib) Kilograms (kg) .4536

Degrees Fahrenheit (°F) Degrees (°C) Temp °C=(temp °F-32)/1.8

IV Contents
EVOLUTION OF SEDIMENTARY BASINS-APPALACHIAN BASIN

Structural and Stratigraphic Framework of the Giles 

County Area, a Part of the Appalachian Basin of 

Virginia and West Virginia

By Robert C. McDowell and Arthur P. Schultz

Abstract

The Giles County area is in the western part of the 

Valley and Ridge province, just south of the Appalachian 

bend near Roanoke, Va. The area is underlain by rocks of 

the eastern central Appalachian basin that range in age 

from Early Cambrian to Late Mississippian and occur in 

linear folds cut by thrust faults. The rocks, well exposed 

along the New River, represent a relatively continuous 

succession of carbonate platform and clastic basinal 

deposits that is about 15,000 ft thick.

Major structures in the area trend about N. 65° E., 

typical of the northern part of the southern Appalachians. 

Thrust faults and axial surfaces of folds dip to the southeast. The major thrust faults are the Pulaski, Saltville, 

Narrows, and St. Clair, and the surface traces of the latter 

three terminate just northeast of the study area, in the 

Roanoke bend. The Narrows fault block contains several 

major synclines and anticlines, notably the doubly plunging Bane anticline of problematic origin, which is the site 

of an exploratory test well. Recent studies conclusively 

show that the area was deformed in a thin-skin style 

without direct involvement of Precambrian basement 

rocks.

The largest earthquake known to have occurred in 

Virginia took place near Pearisburg in 1897. Minor earthquakes have persisted in the Giles County area. Although 

their origin is not well understood, they appear to originate at great depth in basement rocks.

Mineral resources in the Giles County area include 

iron, manganese, limestone, and various sources of aggregate. Limestone is the main resource currently being 

developed. Geologic hazards include landslides, flooding, 

earthquakes, and karst terrain. None appears to represent 

a major problem, although the potential for a major 

earthquake is not yet well known.

Manuscript approved for publication May 18, 1989.

INTRODUCTION

The area of this report includes Giles County in 

southwestern Virginia and adjacent parts of the surrounding 

counties in Virginia and West Virginia (figs. 1,2). The map 

area is in the eastern central Appalachian basin and is 

mainly in the western part of the Valley and Ridge structural 

province, just southwest of a 30° bend in the trend of the 

Appalachian erogenic belt near Roanoke, Va. (figs. 1,2). 

The northwestern part of the area is west of the Allegheny 

Front in the Allegheny Plateau province. The study area is 

underlain by sedimentary rocks of Early Cambrian to Late 

Mississippian age that have been deformed into long, linear 

fold belts cut by several major thrust faults.

The Giles County area is of special geologic interest 

because the epicenter of the largest earthquake recorded in 

Virginia (Modified Mercalli intensity (MMI) of VIII), 

which occurred in 1897, was near Pearisburg (Campbell, 

1898; Hopper and Bollinger, 1971, p. 54-66). Recent work 

has identified a seismogenic zone within Giles County that 

may be associated with that event (Bollinger and Wheeler, 

1980, 1983; Bollinger, 1981).

In the Giles County area, the New River turns from 

its northeastward course, along strike, and cuts northwestward across the grain of the Appalachian foreland. Extensive exposures of bedrock along its course across the folded 

and faulted Valley and Ridge belt make the area particularly 

useful for interpreting the geology and geologic evolution 

(see, for example, Butts and others, 1932; Cooper, 1961, 

1964, 1968; Bartholomew and others, 1980). In this report, 

we provide details of the stratigraphy and structural geology 

of this important area, discuss the development of ideas on 

its tectonic evolution, and describe the economic aspects 

(including hazards) of the geology. The area was selected 

for study because of its relatively high levels of historical 

and present-day seismicity. Numerous investigations and

Structural and Stratigraphic Framework, Giles County, Virginia and West Virginia E1
37'

PENNSYLVANIA

TENNESSEE

COASTAL 

NORTHCAROLINAX

Figure 1. Structural provinces of the Appalachians of Virginia and West Virginia. Location of area of plate 1 is also 

shown.

extensive geologic mapping within the area by various 

workers in recent years, as well as those done for this study, 

make it possible to characterize the geology in considerable 

detail and provide an exceptional opportunity to analyze the 

geologic evolution of this part of the Appalachian foreland. 

The map of Giles County and vicinity (pi. 1) was 

prepared by compiling the geologic maps in numerous 

published and unpublished reports between 1944 and 1986, 

supplemented by field checking and detailed and reconnaissance mapping by the authors between 1979 and 1987. 

Figure 3 indicates the source and coverage of most of the 

previous mapping; other reports used in the compilation 

include maps of Mercer and Monroe Counties, West Virginia (Reger, 1926), and geologic maps by Cooper (1944a, 

pi. 3; 1963, pi. 2.1) and Houser (1980, pi. 1). Giles County 

itself occupies about one-half of the map area, and an 

unpublished map of the county compiled by W. A. Moon in 

about 1962, at a scale of 1:31,250, was consulted. Of 

particular value were unpublished quadrangle maps in the 

county, at a scale of 1:24,000, produced by members of the 

Virginia Division of Mineral Resources, including A.P. 

Schultz, C.B. Stanley, T.M. Gathright II, E.K. Rader, 

M.J. Bartholomew, S.E. Lewis, and N.H. Evans (fig. 4), 

and a compilation of these maps at a scale of 1:50,000 by 

Rader and Gathright (Schultz and others, 1986).

STRATIGRAPHY

Strata in the Giles County area form a relatively 

continuous succession of carbonate platform and basinal deposits from the Lower Cambrian Rome Formation to the 

Upper Mississippian Bluestone Formation, a composite 

thickness of about 15,000 ft. These strata are shown on the 

generalized columnar section (fig. 5). Stratigraphic nomenclature used in this report is compared in table 1 to that used 

in Giles County and nearby areas by other workers. The 

following brief descriptions of the units are based in part on 

descriptions by Butts (1940), Cooper (1961), and Lesure 

and others (1982).

Cambrian System

Rome Formation (Lower Cambrian)

The Rome Formation was named by Hayes (1891, p. 

143) for exposures at Rome, Ga. The formation contains the 

oldest red beds of Paleozoic age in the region. In the map 

area, the Rome is composed predominantly of red laminated 

clay shale interbedded with lesser amounts of grayish-green 

clay shale, light- to dark-gray, fine- to medium-grained 

argillaceous dolomite, and yellowish-gray silts tone. The 

Rome crops out only on the culmination of the Bane 

anticline, near Bane, where 250 to 300 ft of the uppermost 

part of the unit are exposed. Good exposures are in readouts 

along State Road 100, where the beds are intensively 

fractured and folded. Rome strata are also exposed locally

E2 Evolution of Sedimentary Basins Appalachian Basin
EXPLANATION

Normal fault^ Teeth on downthrown side

Thrust fault Sawteeth on upper plate

Strike-slip fault Arrows showing relative 

direction of movement

Syncline, showing direction of plunge 

Anticline, showing direction of plunge

WEST VIRGINIA

TENNESSEE

NORTH CAROLINA

Figure 2. Regional structural setting of the Giles County area of Virginia and West Virginia. Counties, West Virginia: ME, 

Mercer; MO, Monroe. Counties, Virginia: BL, Bland; CR, Craig; Gl, Giles; MG, Montgomery; PL), Pulaski. Location of 

area of plate 1 is also shown.

in the belt mapped as Nolichucky Shale and Honaker 

Dolomite southeast of the Pulaski fault.

Abundant mud cracks and ripple marks and sparse 

marine fossils (mainly trilobites) suggest a shallow marine 

shelf environment.

Distinctive red Rome shales are found throughout the 

Valley and Ridge province of Virginia, most commonly on 

the southeastern side of the province. North of Roanoke, the 

unit contains a greater percentage of carbonate beds and is 

generally called the Waynesboro Formation.

Honaker Dolomite (Middle and Upper Cambrian)

The Rome Formation grades upward into gray 

Honaker dolomites; the contact is placed at the top of the 

uppermost red shale bed. The Honaker Dolomite, named by 

Campbell (1897, p. 2) for exposures at the town of Honaker

in nearby Russell County, Virginia, is composed of light- to 

dark-gray, thin- to thick-bedded, fine- to medium-grained 

dolomite. The lower part of the unit is characterized by 

irregular stromatolites; oolitic, fine-grained dolomite interbedded with massive, dark-gray, cherty dolomite characterizes the upper part of the unit.

In the Giles County area, the Honaker Dolomite crops 

out around the Rome Formation in the core of the Bane 

anticline, and the upper part of the unit is exposed along the 

hanging walls of the Narrows, Saltville, and Pulaski faults. 

On the Bane anticline, where the complete formation is 

present, the Honaker is about 1,000 ft thick (Whitman, 

1964). Although the Honaker has previously been assigned 

by most workers to the Middle Cambrian (Miller and 

Meissner, 1977), Derby (1965) showed that uppermost 

Honaker beds contain a Late Cambrian fauna in the Giles 

County area (Markello and Read, 1982, fig. 2).

Structural and Stratigraphic Framework, Giles County, Virginia and West Virginia E3
\ I ^^ ^ Via (1962) 

Chauvin/1957)

rry and 

Repetski 

1979) / / Ovenshine(1961)

80°30'

37°30'

°30' 37°15'

Figure 3. Index to previous mapping in the Giles County area of Virginia and West Virginia.

Figure 4. Index to 1:24,000-scale quadrangles in the Giles 

County area of Virginia and West Virginia.

Nolichucky Shale (Upper Cambrian)

The Honaker Dolomite is conformably overlain by 

the relatively thin Nolichucky Shale, named by Keith 

(1896, p. 2) for exposures along the Nolichucky River in 

northeastern Tennessee. The Nolichucky is composed of

olive- to dark-gray, sparsely fossiliferous shale, thin- to 

medium-bedded gray argillaceous dolomite and olive-gray 

shale partings, and conglomeratic dolomite that contains 

flat, gray dolomite pebbles. The formation is about 50 ft 

thick in the Giles County area (Whitman, 1964).

The Nolichucky Shale is combined with the underlying Honaker Dolomite on the map and, similar to the 

Honaker, is exposed only around the Bane anticline and 

locally in the hanging wall along the Saltville and Narrows 

thrust faults. On the southeastern border of the map area, 

the combined unit has been mapped as Elbrook Dolomite 

(Bartholomew and Lowry, 1979), a name generally applied 

to eastern and northern facies. The Nolichucky Shale in 

southwestern Virginia was studied in detail recently by 

Markello and Read (1981, 1982), who concluded that it was 

deposited in a carbonate-rimmed intrashelf basin. Derby 

(1965) determined the biostratigraphic zonation of the 

Nolichucky in the region on the basis of trilobites and 

demonstrated the onlap-offlap nature of the sequence.

Cambrian and Ordovician Systems

The Knox Group (Upper Cambrian-Lower Ordovician) contains a thick sequence of dolomite, much of it 

cherty, and a minor amount of sparsely fossiliferous limestone and sandstone. The Knox Group, named by Safford 

(1869) for outcrops in northeastern Tennessee, is commonly

E4 Evolution of Sedimentary Basins Appalachian Basin
I/V31SAS

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tc

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f)

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Mbp

Mhb

!

Mg

Vlmt

D

S

GROUP, FORMATION, 

AND MEMBER

Mauch Chunk Group

RliiRStnnR Formation ': ---.. 

LITHOLOGY

~ ""T-*^-- * ^

^/"^_i~^ir^z

Princeton Sandstone f-v:: ".' . . : :; 

\

Hinton Formation 

I

\ Stonv Gao Sandstone Member L'. . .' ' . - .«&--

>

Bluefield Formation

Greenbrier Limestone

i ' r' 1 ' i ' T

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1 1 Ol J

i si i ror i r1 i i r

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Maccrady Shale JI_n_TZ_r~

Price Formation :

\ 

Brallier Shale

Millboro Shale

___ Huntersville Chert _____ __ -H 

Rocky Gao Sands one t-,. . .

 

'^~z~

Keefer Sandstone fc.'.'X'. X*. . ! ' 

Rose Hill Formation fo'.".i:.';;;;.v.';.' 

Tuscarora Quartzite I-:-:-"' .' » : V % '. *.*." 

(iaaj ui) SS3NX3IHJ

500+

50-125

1,400- 

2,000

U-LIW

1,000- 

1,200

800- 

1,200

20-1,61

350- 

1,500

250- 

700

1,000- 

2,600

850- 

1,000

Hi tl-lillj

00-23d 

100- 

?70 

50-2101

Ojm

Om

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Cnh

 r

Juniata Formation

Martinsburg Formation

Middle Ordovician limestones

Knox Group

Nolichucky Shale

Honaker Dolomite

Rome Formation

/ r i /

.i.-TT-T-..1?;1

_

i, i. Z

1,000- 

1,800

600- 

1,200

2,000 

!,400

1,000- 

1,300

250+

EXPLANATION

i i ~i 

l. i. 11 Limestone

Argillaceous limestone 

Dolomite 

Shale 

Carbonaceous shale

Calcareous shale 

Sandstone

Figure 5. Generalized columnar section for rocks in the Giles County area of Virginia and West Virginia.

Structural and Stratigraphic Framework, Giles County, Virginia and West Virginia E5
Table 1. Stratigraphic nomenclature used in this study and other studies in the Giles County area of Virginia and West 

Virginia

s.

System

MISSISSIPPIAN

DEVONIAN

SILURIAN

Mercer, Monroe, and 

Summers Counties, W. Va. 

(Reger, 1926, fig. 6)

C/5 

<U c

<o

CO

 a

6

o

§

s

Bluestone Group

Princeton Conglomerate

Hinton Group

Bluefield Group

Greenbrier Series

Maccrady Series

Pocono Series

Chemung Series

Portage

Genessee-HamiltonMarcellus Series

Oriskany Series 

Helderberg Series

Clinton Series

White Medina Series

Giles County, Va., and 

Mercer County, W.Va. 

(Cooper, 1961, pi. 1)

Bluestone Formation

Princeton Formation

Hinton Formation

Bluefield Formation

"Casper" Limestone

"Ste. Genevieve" Limestone

Hillsdale Limestone

Little Valley Limestone

Maccrady Formation

Price Formation

Parrot Formation

"Chemung" Formation

Brallier Formation

Millboro Formation

Huntersville Formation

Rocky Gap Sandstone

Tonoloway Limestone

"Keefer" Formation

Rose Hill Formation

Tuscarora Sandstone

Botetourt County, Va. 

(McGuire, 1970)

(not exposed)

Price Formation

Chemung Formation

Brallier Formation

Millboro Formation

Needmore Formation

Ridgely Sandstone

Licking Creek Formation

Healing Springs Sandstone

New Creek Limestone

Keyser Formation

Tonoloway Formation

Keefer Sandstone

Cacapon Formation

Tuscarora Formation

Southwestern Virg

(Miller and Meisner, 

Pennington Group

Bluestone 

Formation

Princeton

Hinton 

Formation

Upper red 

Lower me

Sandstone

Little Ston

Gap Mem

Lower red 

Stony Gap 

Sandston

Bluefield Formation

Greenbrier Limestone

Maccrady Shale

Price Siltstone

Chattanooga Shale

Wildcat Valley Sandstone

Tonoloway Limestone

Rose Hill Formation

Clinch

Sandstone

Upper red 

sandston

Lower wh

sandston
Table 1. Stratigraphic nomenclature used in this study and other studies in the Giles County area of Virginia and West 

Virginia Continued

System

ORDOVICIAN

CAMBRIAN

Mercer, Monroe, and 

Summers Counties, W. Va. 

(Reger, 1926, fig. 6)

Red Medina Series

Lower Maysville 

Martins- Group

!£* Eden Group

Trenton Group

Moccasin Series

Stones River 

(Chickamauga) Series

Beekmantown Series

Elbrook? Series

Giles County, Va., and 

Mercer County, W.Va. 

(Cooper, 1961, pi. 1)

Juniata Sandstone

Martinsburg Formation

Eggleston Formation

Moccasin Formation

Witten Limestone

Gratton Limestone

Benbolt Limestone

Pearisburg Limestone

Lincolnshire Limestone

Five Oaks Limestone

Elway Limestone

Blackford Formation

Knox Group

Nolichucky Shale

Honaker Dolomite

Rome Shale

Botetourt County, Va. 

(McGuire, 1970)

Juniata Formation

Martinsburg Formation

Eggleston Formation

Edinburg Formation

Lincolnshire Formation

New Market Limestone

Beekmantown Formation

Chepultepec Formation

Conococheaque Formation

Copper Ridge Formation

Elbrook Formation

Rome Formation

Southwestern Virg

(Miller and Meisner

Juniata Formation

Reedsville Shale

Trenton Limestone

Eggleston Formation

Moccasin Formation

Lower Middle Ordovician

limestone formations

§ 

2 

O

X

o 

n

M

Beekmantown Dol

Copper Ridge Dolo

Maynardsville Limestone

Nolichucky Shale

Honaker Limestone

Rome Formation

su

i.

I

5-

ft) 

ft)

3.

I5*
divided into two or more formations (table 1). In much of 

southwestern Virginia, these formations include the Copper 

Ridge Dolomite of Late Cambrian age and the overlying 

Beekmantown Dolomite of Early Ordovician age (Miller 

and Meissner, 1977). In more southeasterly outcrop belts, 

these formations are separated by the intervening Chepultepec Limestone of earliest Ordovician age (Butts, 1940, p. 

95-101), which has been reported in Giles County in 

outcrop by Frieders (1975) and in well cuttings by Perry and 

others (1979). Cooper (1961, p. 27-30) found no basis for 

subdividing the Knox Group in the Giles County area 

except at the base of Lecanospira-beanng limestone, which 

he considered to be equivalent to the Longview Limestone 

(lowermost Beekmantown) of Alabama. He suggested that 

the systemic boundary occurs within the Knox Group below 

this zone.

The Knox Group is composed mainly of light- to 

medium-gray, fine- to medium-grained dolomite, commonly stromatolitic or less commonly oolitic, in laminae to 

massive beds. Several distinctive and locally resistant units 

of fine- to coarse-grained, light-brown, dolomite-cemented 

sandstone and light-gray sandy dolomite occur in beds a few 

inches to several feet thick within the lower half of the Knox 

Group. The upper half contains scattered beds of lightbluish-gray calcilutite containing stylolites and intraclast 

zones. Chert is common throughout the Knox, particularly 

in the upper part, as irregular beds as much as 3 ft thick and 

as concentrically banded nodules, generally white to light 

gray but locally black in the lower Knox.

The marine shelf carbonates of the Knox Group are 

2,000 to 2,400 ft thick in the Giles County area (Butts and 

others, 1932; Cooper, 1944a, 1961). The Knox is widely 

distributed through the area, mainly in a wide belt around 

the Bane anticline, in the core of the Clover Hollow 

anticline, and in linear belts in the hanging walls of the 

Saltville, Narrows, and St. Clair thrust faults. It is well 

exposed along the New River (for example, at Goodwins 

Ferry, Pembroke, and Ripplemead and in the Narrows).

Ordovician System

Middle Ordovician limestones

The upper contact of the Knox Group is an irregular 

erosion surface having as much as 100 ft of relief and 

overlain by a sequence composed mostly of limestone. This 

sequence, 600 to 1,200 ft thick, has been subdivided on the 

basis of fossils, grain size, and compositional variations 

into as many as 10 formations (Butts, 1940; Cooper, 1944a, 

1961) (table 1), each of which is generally 50 to 150 ft 

thick. These formations have been interpreted by Read 

(1980) to be carbonate ramp and foreland basin facies 

associated with downwarp and transgression of exposed 

Knox shelf carbonates.

The basal unit of this sequence, the Blackford Formation, is composed of interbedded dolomite, argillaceous

dolomite, calcareous dolomite, and minor dolomitic limestone and red to gray mudrock. In most places, the basal 

bed is a breccia or conglomerate composed of angular to 

subrounded clasts of light-gray to black chert. Locally, 

these rocks fill depressions (sink holes) on the post-Knox 

unconformity that, in some places within the region, extend 

as much as 210 ft below the erosion surface (Mussman and 

Read, 1986). In the map area, the Blackford is about 2 ft to 

as much as 130 ft thick and is succeeded by several hundred 

feet of limestone grading upward to calcareous shale and 

siltstone. The limestone (from the bottom upward, Elway, 

Five Oaks, Lincolnshire, Pearisburg, Benbolt, Gratton, and 

Witten) is predominantly light to medium gray, fine grained 

to cryptocrystalline, and fossiliferous and commonly contains dark-gray chert lenses and nodules. Lesser amounts of 

coarse-grained limestone are interbedded in the section. 

Fossils are mainly brachiopods and bryozoans but include 

trilobites, echinoderms, corals, and other forms. Limestone 

in the upper part of this section is argillaceous, darker in 

color, and irregularly bedded and contains shale interbeds. 

The Moccasin and Eggleston Formations, at the top of the 

sequence, are composed of red, argillaceous, fine-grained 

limestone and red calcareous mudstone (Moccasin) and 

interbedded gray siltstone and fine-grained limestone (Eggleston). The Eggleston contains several thin "bentonite" 

(metatuff) beds (Rosenkrans, 1936).

The Middle Ordovician limestones are distributed 

throughout the Giles County area and, together with the 

Knox Group and older dolomites and shales, form the 

bottoms of linear valleys and the rolling lowlands of the 

Bane anticline area and along the New River. Excellent 

exposures are in river bluffs near Eggleston and Goodwins 

Ferry. The Moccasin Formation is well exposed along U.S. 

Highway 460, north of Newport near Trigg, and in the 

Narrows of the New River; in good exposures, the characteristic small-scale folding and fracturing of the formation 

are striking.

Martinsburg Formation

The Eggleston Formation is succeeded over a thin 

gradational zone by a thick sequence of interbedded limestone, shale, siltstone, and sandstone. This Middle and 

Upper Ordovician fossiliferous sequence, named Martinsburg Shale by Geiger and Keith (1891, p. 161) for less limy 

and less fossiliferous beds exposed near Martinsburg, W. 

Va., is mainly on the middle and lower slopes of mountains 

and is generally covered by colluvium. In the Giles County 

area, the lower half of the unit is composed of fossiliferous, 

fine-grained, gray, thin- to medium-bedded limestone and 

interbeds of calcareous shale and siltstone. These beds 

grade upward into a sequence of interbedded shale and 

calcareous siltstone and sandstone, coarsest at the top. The

E8 Evolution of Sedimentary Basins Appalachian Basin
distinctive large brachiopod Orthorhyncula linneyi is near 

the top of the formation. The Martinsburg, about 1,300 ft 

thick in the Giles County area, was deposited in shallow 

marine waters, the sediment supply of which apparently is 

derived from Taconic orogenic activity to the south and 

southeast (Walker, 1970). Kreisa (1980) attributed most of 

the formation to storm deposits. Excellent exposures are 

located along U.S. Highway 460 in the Narrows.

The Martinsburg Formation is combined with the 

overlying Juniata Formation on the geologic map (pi. 1).

Juniata Formation

Gray shale and sandstone of the Martinsburg Formation are succeeded gradationally by interbedded red sandstone, siltstone, and shale of the uppermost Ordovician 

Juniata Formation. The Juniata was named by Darton and 

Taff (1896) for exposures along the Juniata River in 

Pennsylvania. Together with the underlying Martinsburg 

Formation, with which it is combined on the geologic map, 

it underlies most of the mountain slopes in the Giles County 

area.

The Juniata Formation was deposited mostly as a 

delta-plain mudflat (Kreisa, 1980) and is composed mainly 

of fine-grained, grayish- to dusky-red sandstone that is 

commonly in planar crossbedded sets as thick as 1 ft. Minor 

dusky-red clay shale is interbedded in the lower part of the 

unit and minor grayish-red fissile siltstone and silt shale in 

the upper part. Lingula fragments and reduction spots are 

locally common. The Juniata in the Giles County area is 

about 150 to 375 ft thick (Ladd and Stead, 1944; Cooper, 

1963). It is well exposed along U.S. Highway 460 in the 

Narrows, where it is 325 ft thick (Hale, 1961); on Gap 

Mountain, where the basal contact is covered; and along 

Stony Creek between Olean and Interior. It generally 

occupies steep outcrop slopes just below the crest of ridges, 

where it is commonly covered by cobbles and boulders of 

the overlying Tuscarora Quartzite.

Silurian System

Tuscarora Quartzite

The Lower Silurian Tuscarora Quartzite, a distinctive 

ledge-forming orthoquartzite, is exposed along the crest of 

most of the ridges throughout the Valley and Ridge province of Virginia and West Virginia. The formation was 

named by Darton and Taff (1896) for Tuscarora Mountain 

in Pennsylvania. In Virginia, the unit has been called Clinch 

Sandstone by some workers (for example, Butts, 1940), a 

name still used in southwesternmost Virginia (Miller and 

Meissner, 1977). It is composed of very light gray, fine- to 

coarse-grained quartzite in medium to thick, well-indurated 

beds. Minor lenses of quartz-pebble conglomerate are 

present locally; elsewhere, the grains are well sorted.

Crossbedding (both trough and planar) is common, generally in thick sets, and sparse worm burrows (Skolithos and 

Arthrophycus) are the only fossils. Upper and lower contacts are gradational and are placed at the lowest and highest 

red beds, respectively.

The Tuscarora Quartzite crops out on ridge crests 

throughout the Giles County area. Good exposures are 

found along U.S. Highway 460 at Gap Mountain and the 

Narrows of the New River and along Stony Creek near 

Olean. Most of the mountain slopes and many valley 

bottoms are covered with colluvium in blocks as much as a 

few tens of feet across; the origin and emplacement of this 

material have been described by Mills (1981, 1988).

The Tuscarora has been described as littoral marine in 

origin (Folk, 1960; Hayes, 1974) but more commonly as 

fluvial (Lowry, 1960; Yeakel, 1962; Dennison, 1970) or as 

representing some combination of the two environments 

(Lampiris, 1975). The unit is 50 to 210 ft thick in the Giles 

County area, about 125 ft thick on Gap Mountain (Spencer, 

1970), 50 to 60 ft thick on Little Stony Creek (Eckroade, 

1962; Hayes, 1974), about 100 ft thick in the Narrows of 

the New River (Hale, 1961; Hayes, 1974), and 210 ft thick 

on Johns Creek Mountain at the northeastern end of Clover 

Hollow (Hayes, 1974).

Rose Hill Formation

The Tuscarora is succeeded by red hematitic sandstone and shale of the Middle Silurian Rose Hill Formation, 

named by Swartz (1923) for exposures at Cumberland, Md. 

In some reports, the Rose Hill is included in the Clinton 

Group; the Rose Hill in the Giles County area is apparently 

equivalent to the basal unit of that group, the Cacapon 

Sandstone (Dennison, 1970). The Rose Hill is composed of 

dark-grayish-red, medium- to coarse-grained, locally pebbly, hematite-cemented sandstone and lesser amounts of 

interbedded, fossiliferous, burrowed red siltstone and shale. 

Sandstone beds locally include clay galls; some beds are 

greenish gray or mottled. The Rose Hill is probably a 

lagoonal facies representing marine transgression over the 

Tuscarora sands (Lampiris, 1975, p. 60). Thick beds of 

sandstone in the Rose Hill form conspicuous ledges on or 

just below ridge crests. The formation is 150 to 270 ft thick. 

Excellent exposures crop out along U.S. Highway 460 on 

Gap Mountain, where the unit is about 240 ft thick 

(Lampiris, 1975), and in the Narrows of the New River, 

where it is 200 to 235 ft thick (Hale, 1961; Lampiris, 1975).

Keefer Sandstone

Red sandstones of the Rose Hill Formation are 

overlain by very light gray sandstone of the Middle Silurian 

Keefer Sandstone in a gradational sequence similar in 

general appearance to the Juniata Formation-Tuscarora 

Quartzite succession. The Keefer was named by Ulrich 

(1911) for exposures on Kiefer Mountain in Maryland.

Structural and Stratigraphic Framework, Giles County, Virginia and West Virginia E9
Because of differences in lithology, thickness, and age of 

the formation in the Giles County area, the name has been 

used informally by some workers in the area (Dennison, 

1970). Butts (1918, 1940) treated the Keefer and the 

underlying Cacapon (Rose Hill) as members of the Clinton 

Formation. In the Giles County area, the Keefer is composed predominantly of gray to light-gray, fine- to coarsegrained sandstone and quartzite that are locally crossbedded 

or ripple marked, burrowed (Skolithos), and interlayered 

with minor reddish-brown sandstone beds. It forms prominent flatirons on dip slopes of ridges and locally crops out 

as ledges on the crests. Good exposures are seen along U.S. 

Highway 460 in the Narrows of the New River, where the 

unit is about 100 ft thick (Hale, 1961), and on Gap 

Mountain, where it is 220 ft thick (Spencer, 1970). The 

formation is also well exposed along Stony Creek.

Tonoloway Limestone

A thin, poorly exposed limestone sequence overlies 

the Keefer Sandstone. This Upper Silurian unit, named 

Tonoloway Limestone by Ulrich (1911) for outcrops on 

Tonoloway Ridge in Maryland, is exposed in only a few 

places in the Giles County area and may be absent in the 

southeastern part of the area (Ovenshine, 1961, p. 52). 

Outcrops are in the Dismal Creek drainage in western Giles 

County, on the southeastern slopes of East River Mountain 

west of the town of Narrows, and along Stony Creek near 

Interior. Elsewhere, the presence of this unit is indicated by 

reddish-brown clayey soil, small sinkholes, or a distinct 

slope break; it also has been penetrated by shallow drill 

holes on Flat Top Mountain (Ladd and Stead, 1944). The 

lower part of the Tonoloway consists of cyclic sequences of 

fine-grained to cryptocrystalline fossiliferous limestone, 

dark-gray silty and calcareous shale, and dark-gray massive 

limestone. The upper part of the formation is composed of 

thinly laminated, calcareous, dark-gray siltstone and shale, 

fine-grained cross-laminated sandstone, and minor fossiliferous limestone. The thickness of the Tonoloway locally 

exceeds 100 ft (Via, 1962) but in most places is less than 50 

ft thick.

Devonian System

Rocky Gap Sandstone

Silurian strata in the Giles County area are overlain 

by a distinctive friable, coarse-grained, crossbedded sandstone that is generally ferruginous or manganiferous. This 

Lower Devonian unit was named the Rocky Gap Sandstone 

by Swartz (1929a, p. 82-83) for exposures near Rocky Gap 

in Bland County, Virginia, about 4 mi west of the Giles 

County boundary. Many early reports refer to the formation 

as Becraft Sandstone (Mathews and Pegau, 1934; Butts, 

1940; Ladd and Stead, 1944). The Rocky Gap at the type

locality now traversed by Interstate Highway 77 was 

described by Swartz (1929b, p. 68-69) as the "calcareous 

sandstone" unit of the Giles Formation of Campbell (1894). 

A nearby section, at Bluefield, Va., was described by 

Cooper (1944b, p. 126-130). The Rocky Gap locally forms 

flatirons on the lower slopes of ridges. Good exposures in 

the Giles County area are found on Gap Mountain along 

U.S. Highway 460, in the gap through Brushy Mountain 

between Mechanicsburg and White Gate, in numerous 

abandoned manganese pits on Flat Top Mountain (Lesure 

and others, 1982), and elsewhere throughout the area. The 

Rocky Gap is composed of light-brown, medium- to coarsegrained, crossbedded calcareous sandstone containing 

vuggy molds of brachiopods and crinoids. Crossbeds are 

large scale and planar. Iron and manganese streaks, blebs, 

and stains are common. The calcareous cement is readily 

removed by weathering, which leaves a friable, indistinctly 

bedded outcrop. The formation has an average thickness of 

65 to 75 ft (Cooper, 1961).

Huntersville Chert

The lower slopes of many ridges in the Giles County 

area are littered with chert rubble that has weathered from a 

thin but persistent interval of bedded chert overlying the 

Rocky Gap Sandstone. This Lower and Middle Devonian 

unit is the Huntersville Chert, named by Price (1929) for 

exposures near the town of Huntersville in Pocahontas 

County, West Virginia. The unit was previously called 

Onondaga Chert or Onondaga Formation (Mathews and 

Pegau, 1934; Butts, 1940; Ladd and Stead, 1944). The 

Huntersville is a massive and irregularly bedded, highly 

fractured, light- to dark-gray chert; it generally is poorly 

exposed and is about 50 ft thick in most of the area. A good 

exposure occurs in a road-metal quarry on the northwestern 

side of the town of Narrows.

Millboro Shale

The Huntersville Chert is succeeded by a thick 

sequence of olive-gray to grayish-black, highly fissile clay 

shale, which was named Millboro Shale by Butts (1940, p. 

308) for exposures near Millboro Springs in Bath County, 

Virginia. The sparsely fossiliferous Middle and Upper 

Devonian shale occurs throughout the Giles County area in 

synclinal valleys of the St. Clair and Narrows thrust blocks 

and in Little Walker and Craig Creek valleys of the Saltville 

thrust block. Parts of the section are well exposed in 

roadcuts, borrow pits, and stream banks. Thin sequences of 

black shale, probably Millboro, occur locally just below the 

St. Clair thrust on the overturned limb of the Glen Lyn 

syncline. The upper contact of the formation is gradational 

over several tens of feet. The thickness of the Millboro is 

difficult to determine because of repetition of beds by 

folding and faulting, but Cooper (1961, 1963) reported a 

thickness of 850 to 1,000 ft.

E10 Evolution of Sedimentary Basins Appalachian Basin
Brallier Shale

Dark-gray shales of the Millboro Shale grade upward 

into cyclic, brown, sparsely fossiliferous silty shale and thin 

beds of siltstone and sandstone. This Upper Devonian 

sequence was named Brallier Shale by Butts (1918) for 

exposures near Brallier Station in Bedford County, Pennsylvania. The Brallier crops out mainly in the No Business 

and Dismal Creek drainages in the southwestern part of the 

area, on outcrop slopes of Big Walker and Brush Mountains, and along the footwall of the St. Clair thrust fault. 

The Brallier probably represents distal flysch deposits. 

Typical lithologies include light-brown, fine-grained sandstone, light-gray to greenish-gray siltstone, and minor 

light-gray shale. Both the amount of sandstone and the 

thickness of the beds increase upward through the section; 

sandstone beds are 3 in thick or less near the base and as 

much as 1.5 ft thick at the top; very thick, massive, 

fine-grained sandstone beds also occur locally near the 

base. The upper contact is gradational and is generally 

placed (with difficulty) at the base of the lowest, mediumgrained, crossbedded, fossiliferous sandstone 6 ft or more 

thick. The Brallier is about 2,000 ft thick in the Giles 

County area (Cooper, 1961, 1963).

Chemung Formation

Thin-bedded silty shale, siltstone, and sandstone of 

the Brallier Shale grade upward into thick-bedded, finegrained, slightly calcareous, locally fossiliferous (mainly 

brachiopods) sandstone and interbedded siltstone and shale. 

Sandstones locally have sole marks and may be turbidites of 

a proximal flysch facies. In the study area, this Upper 

Devonian sequence has been called the Chemung Formation 

on the basis of presumed correlation with the Chemung 

Group of Hall (1839) near Elmira, N.Y., and it apparently 

includes at the top the Parrott Formation of Glover (1955) as 

used by Cooper (1961, p. 59). Because of Stratigraphic 

revisions in the type area, the name "Chemung" probably is 

no longer appropriate in the Giles County area.

The Chemung crops out in a narrow belt on the 

northwestern (outcrop) slope of Cloyds and Brush Mountains in Pulaski and Montgomery Counties. Much of it is 

exposed along State Route 100 on Cloyds Mountain and 

along the New River in the gap between Cloyds and Brush 

Mountains, where it is about 700 ft thick (Cooper, 1963, p. 

23) (here it is equivalent to Cooper's Parrott Formation and 

Broadford Sandstone, combined). Overturned Devonian 

beds beneath the St. Clair thrust include all or part of the 

Chemung.

Mississippian System

Price Formation

Clastic marine beds of the Chemung Formation are 

succeeded by the mostly terrigenous, coal-bearing Lower

Mississippian Price Formation, named by Campbell (1894, 

p. 177) for exposures on Price Mountain, a window in the 

Pulaski thrust sheet in Montgomery County, Virginia, a few 

miles southeast of the map area (fig. 2). The Price is 

composed mainly of planar-crossbedded sandstone that 

generally is feldspathic and micaceous and commonly 

contains lithic fragments. The base of the formation in most 

places is marked by one or more ledges of light-gray 

quartz-pebble conglomerate or conglomeratic quartzite, the 

Cloyd Conglomerate Member of Butts (1940, p. 343); 

elsewhere, it is arbitrarily placed within a gradational 

sequence. Siltstone and shale or mudstone interbeds 

increase in abundance upward in the section. Thin coal 

beds, including two seams that have been commercially 

mined, are near the middle of the unit.

The Price Formation is in a belt encompassing the 

southeastern (dip) slopes of Cloyds and Brush Mountains; 

the Cloyd Conglomerate Member crops out along the crests. 

It is also in a second belt northwest of Peters Mountain and 

the St. Clair fault, and, in Monroe County, West Virginia, 

the unit underlies Little Mountain. It is exposed along U.S. 

Route 460 on Brush Mountain and along State Route 100 on 

Cloyds Mountain, where it is about 1,000 ft thick (Cooper, 

1963, p. 22), and along the New River near Rich Creek, 

where it is 500 to 600 ft thick (Dally, 1956; Hale, 1961). 

The Cloyds Conglomerate Member on Cloyds Mountain 

generally is about 25 ft thick but locally is much thicker.

The Price Formation has been described by Kreisa 

and Bambach (1973) as a regressive sequence composed of 

lithofacies representing eight depositional environments, 

ranging from marine shelf to delta plain and swamp.

Maccrady Shale

The Price Formation grades upward into and interfingers with reddish-brown shale and siltstone of the Lower 

Mississippian Maccrady Shale. The formation was named 

by Stose (1913, p. 233-234) for the town of Maccrady, 

southwest of the map area in Smyth County, Virginia, 

where the unit contains beds of gypsum, anhydrite, and salt. 

The Maccrady is the youngest formation in the Valley and 

Ridge province of Virginia, where it is everywhere succeeded by older beds in thrust-fault contact. It occurs in two 

linear belts in the Giles County area: on the southeastern dip 

slopes of Cloyds and Brush Mountains, where as much as 

1,600 ft of beds are preserved beneath the Pulaski thrust 

(Cooper, 1963, p. 22), and northeast of Peters Mountain, 

where only about 20 to 25 ft form a complete section (Butts, 

1940, p. 363; Hale, 1961, p. 38). The formation was 

probably deposited in a shallow, arid marine basin that was 

actively subsiding on its southeastern margin.

Because of the great thickness of the Maccrady in the 

southeastern belt and in the Price Mountain window and 

because the formation ranges in age in the window to as

Structural and Stratigraphic Framework, Giles County, Virginia and West Virginia E11
young as Chesterian, Cooper (1961, 1963) renamed the 

formation in these areas "Stroubles Formation," but this 

usage has not been generally accepted.

Greenbrier Limestone

Red shale and siltstone of the Maccrady Formation 

interfinger with overlying carbonate rocks of the Upper 

Mississippian Greenbrier Limestone along the northwestern 

margin of the map area. Although its first use is unclear 

(Reger, 1926, p. 445-446), the name is derived from the 

Greenbrier River in nearby Greenbrier and Pocahontas 

Counties, West Virginia. The unit is generally given formational rank in Virginia and group rank in West Virginia. 

In Giles County, the interval has been subdivided into 3 or 

4 (Butts, 1940; Cooper, 1961) to as many as 11 formations 

(Reger, 1926); these divisions generally have been defined 

by faunal elements and have been inconsistently applied. 

The contact of the Greenbrier with the underlying Maccrady 

is poorly exposed in Giles County and is generally mapped 

at the last appearance of red shale float and the first 

appearance of limestone outcrops or karst topography. The 

Greenbrier Limestone is on the overturned limb of the Glen 

Lyn syncline and, to the northeast, in its trough; it is well 

exposed in railroad cuts along New River and Wolf Creek, 

north of Narrows, where it is about 1,000 ft thick.

The Greenbrier is composed of medium- to darkgray, locally oolitic or fossiliferous calcilutite and calcisiltite. Dark-gray to black, irregularly bedded cherts are 

common. Lesser amounts of argillaceous and dolomitic 

calcilutite, calcareous shale, and minor siltstone are interbedded with calcilutite and calcisiltite. The formation probably formed on a shallow marine shelf.

Mauch Chunk Group

Upper Mississippian beds above the Greenbrier 

Limestone in the Giles County area are included in the 

Mauch Chunk Group, which is primarily a sequence of red 

and variegated shale and lesser amounts of sandstone and 

siltstone. The Mauch Chunk, first used by Lesley (1876) for 

exposures at the town of Mauch Chunk (now Jim Thorpe) in 

eastern Pennsylvania, is about 3,000 ft thick in the Giles 

County area (Arkle and others, 1979, p. 16). In this area, 

the group is divisible into four formations the Bluefield, 

Hinton, and Blue stone Formations and the Prince ton Sandstone. Huddle and others (1956, p. 540-543) noted that the 

"key sandstones" that form the basis for this subdivision the Princeton Sandstone and the Stony Gap Sandstone Member of the Hinton Formation are probably 

lenticular and that their correlation in subsurface studies is 

uncertain. Recent mapping by the authors (pi. 1) shows that 

the Stony Gap pinches out in Monroe County, West 

Virginia.

Bluefield Formation

The Bluefield Formation contains beds transitional 

between the marine limestone of the underlying Greenbrier 

Limestone and the terrigenous shale and mudstone typical 

of the Mauch Chunk Group. The formation, named by 

Campbell (1896, p. 3) for exposures near Bluefield, W. 

Va., consists of argillaceous, fossiliferous limestone and 

calcareous shale interbedded with gray to green clay shale 

that grades upward into micaceous green to maroon shale 

and mudstone and sparse interbeds of sandstone and siltstone. The upper Bluefield is generally devoid of fossils and 

locally contains a few thin coal beds.

The basal contact of the Bluefield Formation is sharp 

and distinctive in Giles County, although it is locally 

gradational elsewhere. It is placed at the top of oolitic, 

fossiliferous limestones, which are overlain by much less 

resistant calcareous shales of the Bluefield. The upper 

contact is placed at the base of the Stony Gap Sandstone 

Member of the Hinton Formation. The distinctive pebbly 

quartzite pinches out in northeastern Monroe County, West 

Virginia, and, in that area, the Bluefield and Hinton cannot 

be differentiated.

The Bluefield Formation is in a narrow belt on the 

overturned southeastern limb of the Glen Lyn syncline in 

Giles County and in Mercer and southernmost Monroe 

Counties, West Virginia. Humphreville (1981) reported a 

thickness of 1,415 ft for the formation at Glen Lyn, where 

most of the unit is well exposed along railroad cuts. The 

uppermost beds of the formation are well exposed nearby in 

roadcuts along U.S. Highway 460.

Hinton Formation

The Bluefield Formation is overlain by a similar 

sequence of red, green, and gray arenaceous shale and 

calcareous siltstone and a few thin beds of fossiliferous 

limestone and coal. This sequence was named Hinton 

Formation by Campbell and Mendenhall (1876) for exposures near Hinton in Summers County, West Virginia. It 

has a hard, resistant, pebbly quartzite at the base, named the 

Stony Gap Sandstone Member by Reger (1926) for exposures between Bluefield and Princeton in Mercer County, 

West Virginia. The Hinton is as thick as 2,000 ft in the 

Giles County area (Cooper, 1971, p. 97), and the Stony 

Gap Member ranges from 0 to 100 ft thick. Northeast of its 

pinchout, near Lindside, W. Va., the Hinton cannot be 

differentiated from the underlying Bluefield Formation. The 

Stony Gap Member lies along the southeastern limb of the 

Glen Lyn syncline, and the steeply dipping, resistant beds 

form Stony Ridge. The axis of the syncline, which here 

forms the Allegheny structural front, is in lower Hinton 

shales in most of the Giles County area. The Hinton and 

Stony Gap are well exposed along U.S. Highway 460 near 

Oakvale, W. Va.

E12 Evolution of Sedimentary Basins Appalachian Basin
Princeton Sandstone

A light- to medium-gray resistant sandstone (locally 

conglomerate) caps or rims higher elevations in northeastern Mercer County, West Virginia. This unit, named 

Princeton Conglomerate by Campbell and Mendenhall 

(1876, p. 487, 489) for the town of Princeton in the 

southwestern corner of the study area, is 40 to 100 ft thick 

(Campbell, 1896, p. 3; Butts, 1940, p. 403; Cooper, 1961, 

p. 69; Russ, 1969, p. 29). The Princeton is well exposed in 

and around Princeton and along nearby Interstate Highway 

77. Lithologies range from orthoquartzite to subgraywacke; 

pebbles include limestone, chert, quartzite, vein quartz, 

limonite, and shale (Cooper, 1961, p. 69).

Bluestone Formation

The youngest bedrock unit in the Giles County area is 

the uppermost Mississippian Bluestone Formation, named 

by Campbell (1896, p. 3) for exposures along the Bluestone 

River in Tazewell County, Virginia, and Mercer County, 

West Virginia. It is composed of red to gray shale, lesser 

sandstone and siltstone, and a few thin coal beds. The total 

thickness of the Bluestone is about 800 ft (Campbell, 1896, 

p. 3; Russ, 1969), but only about 500 ft are preserved in the 

map area. According to Englund (1968; 1979, p. C14), the 

uppermost beds of the Bluestone Formation, not present in 

the map area, are Early Pennsylvanian in age.

Both the Princeton Sandstone and the Bluestone 

Formation are flat-lying or gently dipping beds of the 

Appalachian Plateau in Mercer County, West Virginia, in 

the southwestern part of the map area.

STRUCTURAL GEOLOGY AND SEISMICITY

Structural Setting

The Giles County area is mostly in the Valley and 

Ridge structural province of Virginia and West Virginia; a 

small part of the area is in the Allegheny Plateau (fig. 1). 

The area is just southwest of a major bend in the Appalachian orogen at Roanoke, Va. (fig. 2). This bend, the 

Roanoke recess, marks the boundary between the central 

and the southern Appalachians. The deformational style of 

the Valley and Ridge province differs conspicuously across 

this boundary; Weaver (1970, p. 125) described this change 

as the "single most striking feature" of the province. 

Northeast of Roanoke, regional folds are the dominant 

structures, and thrust faults are few and relatively unimportant; southwest of Roanoke, including the Giles County 

area, thrust faults dominate, and folds are subordinate in 

scale and significance. Lowry (1971) analyzed in detail this 

contrast in deformation style, and Rodgers (1970a, p. 

39-43) described the nature of the transition zone and 

discussed several possible explanations for the contrast.

The Giles County area is thus within the southern 

Appalachian segment but close to the juncture with the 

central Appalachians. As a result, structures within the area 

are dominated by thrust faults, but several prominent folds 

occur as well (fig. 6). The axis of the northwesternmost 

fold, the overturned Glen Lyn syncline (pi. 1, cross section) 

(McDowell, 1982), forms the boundary between the 

intensely deformed Valley and Ridge province and the 

much less deformed Allegheny Plateau province (fig. 1). 

This boundary is known as the Allegheny Front (fig. 1).

All major structures in the Giles County area follow 

the southern Appalachian trend, about N. 65° E. Thrust 

faults and axial surfaces of the major folds dip to the 

southeast and produce a northwest-verging asymmetry of 

most structures (pi. 1). Surface structures (fig. 6) are well 

known from mapping, but structures at depth are more 

problematic and have been interpreted in various ways 

(fig. 7).

Regional Structures

The Giles County area contains four major thrust 

faults and several map-scale folds, all of which have been 

deformed locally by numerous minor structures (fig. 6). 

The thrusts are, from southeast to northwest, the Pulaski, 

the Saltville, the Narrows, and the St. Clair. The Pulaski 

fault, as commonly traced, extends through the Roanoke 

recess; surface traces of the other three faults terminate in 

the transition zone, within a few tens of miles northeast of 

Giles County (fig. 2). The larger folds include, from 

southeast to northwest, the Spruce Run and Dismal Creek 

synclines, the Clover Hollow anticline, the Johns Creek 

syncline, the Bane anticline, and the Pearisburg and Glen 

Lyn synclines (fig. 6). All are on the Narrows fault block, 

except for the Glen Lyn syncline, which is in the footwall of 

the St. Clair fault. These folds and thrust faults are 

described below in sequence from southeast to northwest.

The Pulaski fault extends for more than 150 mi 

northeast and southwest of the Giles County area and has 

been described as "one of the major thrust faults of the 

Valley and Ridge province of the Appalachians" (Rodgers, 

1970b, p. 175). The thrust, which occurs along the southeastern border of the map area, brings Lower, Middle, and 

Upper Cambrian formations over the Lower Mississippian 

Price Formation and Maccrady Shale. A few miles southeast of Giles County, the Pulaski thrust sheet contains 

several large windows. Complex structures within these 

windows and extensive fault breccia throughout the lower 

part of the thrust sheet have recently been studied in detail 

by Schultz (1986a), who developed a model for the pervasive deformation of the sheet. Bartholomew (1979) estimated a minimum lateral displacement of 33 mi for the 

Pulaski thrust in the Roanoke area.

Structural and Stratigraphic Framework, Giles County, Virginia and West Virginia El 3
HURRICANE RIDGE 

SYNCLINE

\ /' /s WEST VIRGINIA

-U-V » GLENLY^SYNCUNJ, -

^ T-"- (_. --- Mt

ST. CLAIR FAULT

MONROE COUNTY

80°30"

37°30"

EXPLANATION 8no" 37 °15 " 

Normal fault Bar and bail on downthrown side -«- -J- - Syncline, showing direction of plunge

Thrust fault Teeth on upper plate V Overturned syncline 

Giles County seismic zone, trace of medial surface -fr Anticline, showing direction of plunge

 -ft Overturned anticline

Figure 6. Major structural features in the Giles County area of Virginia and West Virginia.

5 MILES

The leading edge of the Pulaski fault overrides 

southeast-dipping beds of the Saltville block, which range 

in age from Middle Cambrian (Honaker Dolomite) to Early 

Mississippian (Maccrady Shale and Price Formation). 

These beds, which occur in a simple homocline, form the 

two mountain ridges and intervening valley along the 

southeastern margin of the Giles County area. The Saltville 

fault, which can be traced some 500 mi southwestward to 

the Coastal Plain of Alabama (Rodgers, 1970a, p. 40), 

gradually loses displacement to the northeast and apparently 

terminates in Devonian shales in the core of the Sinking 

Creek anticline near Newcastle, Va., about 20 mi from 

Giles County. At Greendale in Washington County, Virginia, some 75 mi southwest of the Giles County area, total 

stratigraphic displacement is 14,000 ft (Butts, 1940, p. 

457). At some places, the fault is a single discrete sliding

surface and an inch or less of dolomite gouge; at others, it 

includes multiple sliding surfaces and pervasive cataclasites 

(House and Gray, 1982a). The dip of the fault in exposures 

generally is about 30° but ranges from flat lying near 

Saltville, Va. (Muangnoicharoen, 1978), to almost vertical 

at Berton, in Giles County (Stanley, 1983). Most subsurface models show the fault having listric geometry and 

merging at depth with a master decollement in the Rome 

Formation (fig. 7, interpretations D-G). A narrow horse of 

Cambrian-Ordovician carbonate rocks occurs along the 

trace of the Saltville fault through most of the Giles County 

area. Models of deformation based on microscopic strain 

analysis (House and Gray, 1982a) show that the Saltville 

fault was emplaced under brittle conditions, at temperatures 

of less than 250 °C (depths of 3-5 mi), and that movement 

was both seismic (stick slip) and aseismic (cataclastic flow).

Figure 7. Interpretation of structures along line of section 

A-A' (pi. 1). Stratigraphic units: pC, Precambrian; C, Cambrian; OCk, Knox Group; O, Ordovician rocks; S, Silurian 

rocks; D, Devonian rocks; M, Mississippian rocks. A and D are 

diagrammatic; others are balanced. Tick mark indicates sea 

level. Base of sections is -18,000 ft; no vertical exaggeration. All

sections are slightly modified, mainly to show the same strati-^- 

graphic units. Sources of interpretations: A, Cooper (1961, pi. 

8, 36); B, Perry and others (1979, fig. 4); C, Roeder and others 

(1978, sec. V3); D, Bartholomew and others (1980); E, Woodward and Cray (1985, sec. 16); F, Gresko (1985, fig. 19); G, 

Kulander and Dean (1986, fig. 6, sec. 10).

E14 Evolution of Sedimentary Basins Appalachian Basin
4F. 35* 

tu

a. n

a 

«§'. 35'
Overturned beds of Middle Ordovician to Early 

Devonian age in the footwall of the Saltville fault form the 

southeastern limbs of the Spruce Run and Dismal Creek 

synclines (fig. 6). The axial traces of these synclines are 

overridden near Staffordsville, on U.S. Highway 100, and 

a gap of 2 to 3 mi forms between them. The Spruce Run 

syncline extends for about 20 mi northeastward to the 

southwestern edge of Craig County, Virginia, where it is 

again overridden by the fault. The Dismal Creek (or Brushy 

Mountain) syncline extends southwestward a similar distance, and it, too, is overridden again, beyond the map area, 

in Bland County, Virginia. These two synclines are probably segments of a single structure, represented farther 

southwest by the Greendale syncline of southwestern Virginia and northeastern Tennessee. In the Giles County area, 

dips on the southeastern limbs range from vertical to 45° 

SE. overturned. Dips on the northwestern (common) limbs 

range from 10° to 45° SE. Structural thinning of as much as 

50 percent occurs on the overturned limbs (Stanley, 1983). 

Cleavage and outcrop-scale folding and faulting occur in 

Middle and Upper Ordovician limestones and shales of the 

Spruce Run syncline (Gray, 1981; Simon and Gray, 1982; 

Stanley, 1983).

The Greendale syncline is one of the most prominent 

structures of the southern Valley and Ridge province and 

contains the youngest beds (Upper Mississippian Pennington Formation) southeast of the Allegheny Front. The axial 

trace of the syncline is exposed for a length of about 45 mi 

from Saltville, Va., to near the Tennessee border; in 

Tennessee, where the axial portion is cut out by the Saltville 

fault, Mississippian beds of the northwestern limb extend 

for an additional 125 mi (Butts, 1940, p. 458). The 

Greendale syncline is thus probably the longest continuous 

fold in the southern Appalachians.

A doubly plunging anticline in eastern Giles County 

brings uppermost Knox (Lower Ordovician) rocks to the 

surface in a small but conspicuous axial valley. This small, 

regional-type fold is less than 10 mi long and is just 

northwest of the Saltville fault and the overturned Spruce 

Run syncline (fig. 6). The Clover Hollow anticline is 

slightly asymmetrical, and its axial surface dips to the 

southeast. On the basis of strain indices, as well as model 

studies by House and Gray (1982b), Simon and Gray (1982) 

concluded that the Clover Hollow anticline is a buckle fold 

associated with lateral shortening of the Narrows block 

above a decollement rather than a ramp anticline. Just 

northeast of the Giles-Craig County line, the axis of the 

anticline appears to be cut off by an unnamed thrust.

Just northwest of the Clover Hollow anticline is the 

much larger Johns Creek syncline, which is almost 40 mi 

long. Only the southwestern part of the syncline, plunging 

northeast, is in the Giles County area (fig. 6). Devonian 

beds are preserved in the trough of the syncline.

Central Giles County is dominated structurally by a 

prominent doubly plunging anticline (fig. 6), commonly

called the Bane dome because of its elliptical outcrop shape. 

Red mudstones of the Rome Formation (Lower Cambrian) 

are exposed in the core; the Rome is exposed nowhere else 

northwest of the Pulaski fault in the Giles County area. 

Recent mapping by Perry and Repetski (1979) shows the 

presence of a window on the apex of the Bane dome, near 

Bane, in which uppermost Knox Group dolomite (Lower 

Ordovician) is exposed below a thrust fault. Rocks of the 

Rome Formation are highly deformed, displaying numerous 

mesoscopic upright to recumbent folds, faults, veins, and 

cleavage. Breccia of the Max Meadows type (Cooper, 

1939, p. 59-62) is in isolated localities around the window. 

The anticline crosses the length of Giles County but 

apparently does not extend beyond the county boundaries. 

Near Mountain Lake, the axial trace is displaced by minor 

faults.

In 1948, a test well the P.P. Strader No. 1 was 

drilled for petroleum exploration by the California Company on the apex of the Bane dome to a total depth of 1,443 

ft. The well began in the Rome Formation (Lower Cambrian) and bottomed in sandy and oolitic dolomites believed 

by Cooper (1961, p. 92; 1964, p. 97; 1968, p. 33; 1971, p. 

98) to be Shady Dolomite (Lower Cambrian) and later 

identified by Perry and others (1979) as upper Knox Group 

(Upper Cambrian and Lower Ordovician). Seismic reflection studies (Edsall, 1974; especially Gresko, 1985) reinforced the view that the Bane dome is the result of thrust 

duplication of Cambrian through Devonian rocks.

Northwest of the Bane anticline is the Pearisburg 

(Angels Rest) syncline, which is similar in size and has an 

axial trace roughly parallel to the Bane anticline (fig. 6). 

Lower and Middle Devonian rocks are exposed in the 

trough of the syncline on Pearis and Butt Mountains. A 

culmination is near Pearisburg, at about the same position 

along the axis as the culmination of the Bane dome. As is 

the case for the Bane anticline, the axial trace apparently 

does not extend beyond the county boundaries (fig. 6).

The northwestern part of Giles County is traversed by 

the Narrows thrust fault. Southwest of the New River, the 

fault brings Honaker or Copper Ridge Dolomite (Middle or 

Upper Cambrian) over Silurian and younger beds for some 

40 mi to Tazewell County, Virginia (fig. 2); beyond 

Tazewell County, the displacement of this block is then 

transferred by a series of small thrusts and folds to the 

Copper Creek fault (Grabowski, 1983), which extends 

across Tennessee almost to the Georgia boundary (Rodgers, 

1970a, p. 1). Northeast of the New River, the thrust loses 

stratigraphic displacement and passes into a zone of imbrication in the Peters Mountain-Big Mountain area. The fault 

appears to be continuous through this zone into Monroe 

County, West Virginia (fig. 6). The fault is exposed in a 

railroad cut along the New River, just north of the town of 

Narrows. The hanging wall is relatively undeformed, but 

horse blocks of the footwall are strongly deformed.

E16 Evolution of Sedimentary Basins Appalachian Basin
The northwesternmost thrust fault in the Giles County 

area (fig. 6), and in the northern end of the southern 

Appalachians, is the St. Clair fault. The fault has been 

traced from its northeastern terminus, the core of an 

anticline in Alleghany County, Virginia, some 50 mi from 

the New River, southwestward to the Clinchport and related 

faults of southwestern Virginia and Tennessee (fig. 2), for 

a total length of 380 mi (Harris, 1965). The fault is 

extremely well exposed on U.S. Highway 460 south of Rich 

Creek, Va., where uppermost Knox Group dolomites 

(Lower Ordovician) are in bedding-parallel contact with 

overturned beds of Upper Devonian shale. Although they 

are probably Millboro Shale, these upper Devonian shales 

also have been identified as beds of Brallier Shale (Butts, 

1940, p. 461) or Chemung Formation (Cooper, 1961, p. 59, 

pi. 46A; 1971, pi. 9). Other exposures of the fault can be 

found near Glen Lyn, Va.

Rocks of the footwall of the St. Clair thrust locally 

have been severely deformed, and footwall formations 

commonly have been tectonically thinned. Reconnaissance 

mapping suggests the presence of a series of horses of 

Ordovician and Silurian rocks along the fault near Zenith, 

W. Va., in the northeastern corner of the map area.

The overturned Glen Lyn syncline is just northwest of 

and parallel to the St. Clair fault (fig. 6). Its southeastern 

limb consists of beds ranging from Late Devonian (Brallier 

Shale?) to Late Mississippian (Hinton Formation) in age; it 

is vertical to overturned and dips as low as 30° SE. The 

northwestern limb is flat to gently dipping; the axial trace of 

the syncline forms the boundary between the Valley and 

Ridge and Allegheny Plateau structural provinces, the 

Allegheny Front (fig. 1). Earlier workers (Reger, 1926; 

Cooper, 1961, 1971) refer to this structure as the Hurricane 

Ridge syncline. McDowell (1982) showed that the Hurricane Ridge, named by Campbell (1896), is a separate 

structure of different form, trend, and tectonic significance.

Tectonic Evolution

Current ideas on the structure and tectonics of the 

Appalachian foreland have been summarized by Rodgers 

(1970a) and Hatcher (1981). The Valley and Ridge province is generally characterized as dominated by southeastdipping thrust faults and asymmetric northwest-verging 

folds, both of which pass rather abruptly into the much 

more gently deformed Allegheny Plateau province on the 

northwest. The boundary between these provinces is known 

as the Allegheny Front (Rodgers, 1970a, p. 19, 32) (fig. 1), 

which, in the study area, is along the axial trace of the Glen 

Lyn syncline (fig. 6).

For many years, a controversy over the involvement 

of basement rocks in foreland structures occupied much 

attention (Rodgers, 1949, 1964; Cooper, 1961, 1964, 1968) 

(fig. 7), and structures in the Giles County area were used

to support both sides of this controversy (Cooper, 1964, 

1968; Rodgers, 1964; Thomas, 1966; Milici, 1973). Analyses of drilling data (Gwinn, 1964) and seismic profile data 

(Harris and Milici, 1977) demonstrate a "thin skin" style of 

deformation in this region, an interpretation now universally accepted (fig. 7, interpretations B-G).

Other problems remain not wholly solved. When and 

how were these structures formed? These problems are 

related to the nature of the driving mechanism gravity or 

compression. This controversy was discussed briefly by 

Hatcher (1981, p. 492-493), who pointed out some significant difficulties with the gravity hypothesis. Delineation 

and analysis of structures in the Giles County area are useful 

in addressing these problems.

Interpretations of the structural geology of the Giles 

County area by various authors are shown in sections A 

through G of figure 7. Cross sections A through E and G are 

based on surface mapping and a single well, the California 

Company P.P. Strader No. 1 (total depth 1,443 ft), on the 

apex of the Bane dome. Cross section F also incorporates 

results of seismic reflection profiling. These cross sections 

illustrate several models that have been proposed for the 

structural evolution of the area. The models differ in three 

main respects: (1) basement involvement (thick skin) (fig. 

7, section A) or detachment (thin skin) styles of deformation, (2) subsurface structure responsible for the Bane 

anticline, and (3) sequence of thrust fault development.

The Strader well on the Bane anticline, drilled in 

1948, was cited by Cooper (1964, p. 97-98) as providing 

the evidence that persuaded him of basement involvement 

in the folding and faulting of the Appalachian foreland. He 

believed that the well penetrated a normal stratigraphic 

succession and that the basement lay relatively close to the 

surface (Cooper, 1968, p. 45). His interpretation (fig. 7, 

section A) was supported by Sears and Robinson (1971) on 

the basis of gravity data. Using stratigraphic data from the 

nearby "Hurricane Ridge" (now Glen Lyn) syncline, Thomas (1966) supported Cooper's concept of contemporaneous deformation in this area (Cooper, 1961, p. 100-118; 

1964, 1968), in which folds and thrusts were generated by 

differential subsidence of the basement. This idea was in 

opposition to the prevailing interpretation that Paleozoic 

rocks were detached from the basement and moved laterally 

for great distances (Rich, 1934; Rodgers, 1949, 1953, 

1964; Gwinn, 1964). On the basis of this "thin-skin" 

approach, Milici (1970, 1973) presented interpretations of 

the Giles County area that account for the structures by 

means of detachment ("thin skin") thrusts and a repeated 

section beneath the Bane dome. To resolve this controversy, Byron Cooper and John Rodgers proposed to drill a 

hole on the Bane dome reaching to the basement, which 

Cooper believed was within 2,000 ft and Rodgers believed 

was as deep as 8,000 ft (Cooper, 1971, p. 98). No basement 

test has yet been drilled, but a reexamination of the Strader 

well cuttings by Perry and others (1979), using conodont

Structural and Stratigraphic Framework, Giles County, Virginia and West Virginia El 7
material, reveals that the dolomites below the Rome Formation are from the upper Knox Group rather than the 

Shady Dolomite. Thus, instead of a normal stratigraphic 

succession in the Lower Cambrian, the well penetrated a 

repeated section, a sequence that requires the presence of a 

subhorizontal thrust (fig. 7, section B), as Milici had 

predicted earlier. Subsequent seismic reflection profiling 

confirms this structural model (Gresko, 1985) (fig. 7, 

section F), and all recent interpretations (fig. 7, sections 

B-G) are based on it. Most models suggest a duplex 

structure involving horses (fig. 7, sections B, C, E-G). 

Basement involvement in Appalachian structures is now 

regarded as being limited to indirect effects, such as growth 

structures that were later transported by detachment (Shumaker, 1986; Thomas, 1986; Wheeler, 1986).

The Bane anticline has been related to three types of 

subsurface structures: (1) basement anticline (fig. 7, section 

A), (2) blind thrust (fig. 7, section D), and (3) duplex over 

a basal decollement ramp from Cambrian to Devonian strata 

(fig. 7, sections B, C, E-G). The basement anticline was 

proposed as a "thick-skin" solution and is no longer 

feasible. The duplex models use different tectonostratigraphic units. Sections C and E (fig. 7) involve horses of 

Cambrian and Ordovician rocks, whereas sections B, F, and 

G (fig. 7) have horses composed of Cambrian through 

Devonian rocks. These models generally include beddingparallel thrusts (decollement) in incompetent shales of the 

Rome and Martinsburg Formations and the Millboro Shale. 

In some cases, they require such thrusts in competent 

Middle Ordovician limestones, an occurrence that seems 

less likely.

The sequence of thrusting across the Valley and 

Ridge province also has been problematic. A northwest to 

southeast development of thrust faults, related to a gravitysliding mechanism of origin, was suggested by Milici 

(1975), Harris and Milici (1977, p. 13-14), and Bartholomew and others (1980). This structural model is illustrated 

by section D (fig. 7). Other workers (Perry, 1978; Hatcher, 

1981; Woodward and Gray, 1985) argued that deformation 

progressed from southeast to northwest (hinterland to foreland) as a result of compression (for example, fig. 7, section 

E). Mullenax (1981), in a study of mesoscopic features in 

the Martinsburg Formation in the St. Clair and Narrows 

blocks, found less internal deformation in the St. Clair 

block, an observation that he interpreted as inconsistent 

with gravity-sliding models. Bartholomew and others 

(1982, p. 125) suggested a thrust sequence in the Giles 

County-Roanoke area of Pulaski-St. Clair-Narrows-Saltville, a melding of the two viewpoints. The Narrows fault 

has been interpreted as both a back-limb imbrication of the 

St. Clair thrust (Perry and others, 1979, p. 651; Roeder and 

others, 1978; Gresko, 1985, p. 49) (fig. 7, sections B, C, F) 

and as a splay off the basal detachment zone (Bartholomew 

and others, 1980; Woodward and Gray, 1985, p. 41) (fig. 

7, sections D, E). Of these interpretations, only those of

Perry and others (1979) and Gresko (1985) remain within 

the constraints of surface geology (for example, the presence of Rome Formation on the crest of the Bane anticline 

and significant footwall synclines beneath the thrusts) (fig. 

7, sections B, F).

Seismicity

The Giles County area is within the southern Appalachian seismic zone of Bollinger (1973). The earthquake of 

May 31, 1897, is the largest shock known to have occurred 

in Virginia (Campbell, 1898) and one of the largest in the 

Eastern United States (MMI VIII, mb = 5.8) (Bollinger and 

Hopper, 1971; Nuttli and others, 1979). The area continues 

to be relatively active seismically. In addition to numerous 

microearthquakes, an event of November 20, 1969, near 

Elgood, W. Va., in the southwestern corner of plate 1, 

registered a mb = 4.3 (Bollinger and Hopper, 1970). On the 

basis of current monitoring by a local network and using 

certain previous events, Bollinger (1981) defined a planar 

seismic zone in Giles County (fig. 6) that is about 25 mi 

long, 6 mi wide, and 3 to 15 mi deep and has a nearly 

vertical dip. This configuration places the zone below 

detachment thrusts, as figure 7 shows, and mostly within 

Precambrian basement rocks. Bollinger and Wheeler (1983, 

1988) assumed that the seismic zone was the source of the 

1897 shock and speculated that the most likely fault 

mechanism is reactivation of ancient normal faults produced 

by lapetan rifting, the Late Precambrian to Early Paleozoic 

opening of the ocean basin preceding formation of the 

Atlantic Ocean. An alternative explanation is that the 

seismic zone, which at N. 43° E. is 20° off the trend of the 

overlying detachment structures but close to the trend of 

structures north of the Roanoke reentrant, is related in 

origin to the central Appalachians. Thus, the seismic zone 

might represent a basement fault that influenced the formation of those structures and was later overridden by detachment thrusts of the southern Appalachians.

During field investigations for the present study, an 

extensive search was conducted for neotectonic features at 

the surface, in either bedrock or surficial deposits, that 

could be related to seismic activity. No such features were 

found. Numerous rock falls and slides in the area may have 

been triggered by seismic shaking. Campbell (1898, p. 235) 

reported a "landslide of considerable proportions" on the 

face of Wolf Creek Mountain that was caused by the 

earthquake of 1897. Schultz (1986b) mapped a giant rockslide complex on Sinking Creek Mountain, just east of the 

map area, for which he considered seismic shaking a 

possible initiating mechanism. Mills (1986) reported a 

downstream increase of about 90 ft in terrace elevation 

along the New River across the Giles County seismic zone 

and suggested an origin by fault movement associated with

E18 Evolution of Sedimentary Basins Appalachian Basin
the seismic zone. Such differential uplift cannot be confirmed by structural studies of the bedrock.

MINERAL RESOURCES

The Giles County area contains a modest amount of 

minor mineral resources (iron, manganese, nonmetallic 

minerals, and fossil fuels), although the only resources 

currently being exploited are limestone, dolomite, and 

siliceous aggregate. The mineral resources of part of Giles 

County have recently been evaluated by Lesure and others 

(1982).

Iron

Iron resources are of two types: hematitic sandstone 

of the Rose Hill Formation (Silurian) and limonite in the 

Rocky Gap Sandstone (Devonian) and, to a minor extent, in 

the Tonoloway Limestone and Keefer Sandstone (Silurian). 

The hematite deposits, generally known as Clinton ores, are 

the more important of these submarginal resources (Lesure 

and others, 1982, p. 43).

Hematite is the cementing material between quartz 

grains in numerous beds of the Rose Hill Formation, which 

is widely distributed on mountain crests and slopes in the 

Giles County area. Various investigators have reported that 

one-fourth to one-third of the Rose Hill is composed of 

hematitic sandstone (Lesure and others, 1982, p. 46). 

Cooper (1960, p. 1) indicated that the iron content of the 

sandstones ranges from 23 to 37 percent; Lesure and others 

(1982, p. 47) obtained averages for two collections of 14.1 

and 20.5 percent and reported results from other studies of 

14.0 to 20.7 percent average iron.

Limonite resources, supergene iron deposits commonly referred to as Oriskany ores, have been mined in a 

few locations in the Giles County area. Lesure and others 

(1982, p. 54) considered limonite deposits in this area to be 

small and probably erratic because of the lack of a thick 

limestone underlying source rocks in the Millboro Shale.

Manganese

Manganese ore deposits are widely distributed in 

western Virginia and adjacent West Virginia. They are 

generally restricted to bedrock or residuum at three stratigraphic levels: Shady Dolomite (Lower Cambrian), Knox 

Group (Upper Cambrian and Lower Ordovician), and 

Rocky Gap Sandstone (Lower Devonian) (Stose and Miser, 

1922, p. 49-50). Only the latter two levels are in the Giles 

County area.

Most of the manganese deposits associated with the 

Knox Group are in the Newport district, along Sinking 

Creek, where the manganese is in weathered residual clays

derived from dolomites and dolomite breccias along the 

Saltville fault (Sears, 1957, p. 3). Other prospects are along 

Spruce Run and near Pembroke. All of these deposits are 

shallow and limited in extent and have yielded little ore 

(Stose and Miser, 1922, p. 119-123).

Manganese deposits related to the Rocky Gap Sandstone are of greater importance and have yielded more ore. 

The manganese oxides, in nodules and fracture fillings and 

as cement in sandstone, are associated with Oriskany iron 

ores of the Rocky Gap, but small amounts are also just 

below the formation, in the top of the Keefer Sandstone and 

in clayey residuum over the Tonoloway Limestone. The 

deposits are at this Stratigraphic interval throughout the 

county (Stose and Miser, 1922, p. 123-142), but the most 

productive workings have been in the Flat Top Mountain 

district of southwestern Giles and adjacent Bland Counties 

(Ladd and Stead, 1944). Reserves in this district were 

estimated by Ladd and Stead (1944, p. 224) at 5,000 tons of 

ore, averaging 35 to 40 percent manganese. Lesure and 

others (1982, p. 64) reported that production from the 

Stange mine between 1917 and 1959 was more than 45,000 

tons of manganese ore.

Nonmetallic Resources

Nonmetallic resources in the Giles County area 

include limestone and dolomite, quartz sandstone, shale, 

dimension stone, and phosphate. The economic potential of 

these resources has been described in detail by Lesure and 

others (1982, p. 65-72). Chemical-grade limestone is 

currently being mined from the Five Oaks Limestone 

(Middle Ordovician) at Kimballton, and limestone and 

dolomite for crushed rock have been obtained from Cambrian and Ordovician formations at various localities, notably near Ripplemead and Pembroke. Crushed stone is also 

being quarried from the Huntersville Chert near the Narrows.

No other nonmetallic resources are currently being 

exploited. Cooper (1944b) described the limestone and 

dolomite resources of the area in detail. Mathews and Pegau 

(1934) investigated dimension-stone prospects in "marble" 

from the Moccasin Formation. Clay and shale for industrial 

uses were studied by Johnson and others (1965). Prospects 

for further commercial development of nonmetallic 

resources are slight.

Fossil Fuels

Fossil fuels include coal, oil, and gas. Coal has been 

mined on a small scale along the southeastern slopes of 

Cloyds and Brush Mountains in Montgomery and Pulaski 

Counties, along the southeastern border of plate 1. Oil and 

gas have not been obtained in commercial quantities from

Structural and Stratigraphic Framework, Giles County, Virginia and West Virginia E19
the area, although gas was produced from the A.W. Hicks 

No. 6478 well in western Mercer County, West Virginia 

(Huddle and others, 1956).

Commercial coal is in two minable seams near the 

middle of the Price Formation (Lower Mississippian), the 

Merrimac and Langhorne beds (Campbell, 1925, p. 145). 

The coal beds can be as thick as 6 ft but are generally much 

thinner (Cooper, 1961, p. 61). Most of the coal is considered to be semianthracite in rank (Campbell and others, 

1925, p. 126). Reger (1926, p. 514-518) reported coal in 

the same stratigraphic position in the Price Formation in 

Mercer and Monroe Counties, West Virginia, northwest of 

the St. Clair fault, but the beds are too thin or too impure to 

be of commercial interest. Because of the steep dip and 

other structural complications, the coal in Montgomery and 

Pulaski County is mined only sporadically at present.

Although no oil or natural gas has been discovered in 

commercial quantities in the Giles County area, thermal 

maturity studies suggest that rocks of Mississippian age and 

older are a potential source of natural gas, and structurally 

prospective areas do exist in the area (Perry, 1982, p. 

71-72). Wells drilled northwest of the Glen Lyn syncline 

have encountered shows of natural gas but no commercial 

quantities (Perry, 1982, p. 71). The only test well within 

Giles County, the P.P. Strader No. 1 on the Bane anticline, 

which penetrated upper Rome Formation and upper Knox 

Group, was abandoned without encountering either oil or 

gas (Huddle and others, 1956, p. 531). Stanley and Schultz 

(1983) investigated coal-bed methane possibilities in Montgomery County, Virginia, and concluded that these 

resources are of marginal value.

GEOLOGIC HAZARDS

Environmental hazards related to the geologic features of Giles County are not severe and include landslides, 

karst terrain, floods, and earthquakes.

Slope failures are most likely on steep slopes such as 

mountainsides and along the New River. Instability is 

greater where colluvium is present. In the Giles County 

area, relatively few roads and houses are susceptible to 

significant risk of slope failure. A major exception is U.S. 

Highway 460, 1 mi northeast of Narrows, Va., located on 

a slope composed of brecciated Silurian sandstone along the 

Narrows fault; the slope has been undercut by the New 

River and is slowly, but more or less continuously, failing 

(Cooper, 1961, p. 159; Samford, 1983). Giant ancient 

landslides similar to those described by Schultz (1986b) and 

Southworth and Schultz (1986) have recently been recognized on dip slopes throughout the area. Blocks of Silurian 

sandstones and quartzites as long as 0.6 mi or more have 

failed and slid or toppled from steep dip slopes at and below 

ridge crests. These gravity failures occurred during the 

Pleistocene and early Holocene and currently are not active.

The landslides may be mistaken for Alleghenian structures, 

and care must be taken to differentiate between tectonic and 

surficial features in these settings.

Karst features, including sinkholes, caves, and sinking or underground drainage, are common in much of the 

plate 1 area, principally along the floors of valleys underlain 

by Cambrian-Ordovician carbonate rocks, especially Middle Ordovician limestones. Collapse of such features presents a minor hazard, particularly where the water table has 

been lowered. Subsurface movement of pollutants is generally more rapid and widespread in karst terrain.

Flooding presents a periodic minor hazard on floodplains along the New River and its larger tributaries.

Earthquakes are a hazard of unknown but potentially 

dangerous dimensions. On the basis of an analysis of the 

Giles County seismic zone, Bollinger (1981, p. 281) 

postulated, for emergency planning, a shock having a 

magnitude of ms = 7 and MMI IX. Such a shock would 

result in considerable damage to buildings, including partial 

collapse, and disruption of water supplies and utilities. (The 

largest historical earthquake, in 1897, had MMI XIII, and 

only minor damage resulted). In addition to damage to 

structures, seismic shaking probably would trigger landslides and rockfalls in areas of steep slope.

A map showing slope categories and karst features of 

Giles County was compiled by Miller and Hubbard (1986).

REFERENCES CITED

Arkle, T., Jr., Beissel, D.R., Larese, R.E., Nuhfer, E.B., 

Patchen, D.G., Smosna, R.A., Gillespie, W.H., Lund, R., 

Norton, C.W., and Pfefferkorn, H.W., 1979, West Virginia 

and Maryland, in The Mississippian and Pennsylvanian 

(Carboniferous) Systems in the United States: U.S. Geological Survey Professional Paper 1110-D, 35 p.

Bartholomew, M.J., 1979, Thrusting component of shortening 

and a model for thrust fault development at the central/southern Appalachian junction: Geological Society of America 

Abstracts with Program, v. 11, no. 7, p. 384-385.

Bartholomew, M.J., and Lowry, W.D., 1979, Geology of the 

Blacksburg quadrangle, Virginia: Virginia Division of Mineral Resources Publication 14, 1 sheet, scale 1:24,000.

Bartholomew, M.J., Milici, R.C., and Schultz, A.P., 1980, 

Regional structure and hydrocarbon potential, in Geologic 

structure and hydrocarbon potential along the Saltville and 

Pulaski thrusts in southwestern Virginia and northeastern 

Tennessee: Virginia Division of Mineral Resources Publication 23, pt. A, sheet 1.

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E24 Evolution of Sedimentary Basins Appalachian Basin
Chapter F

Late Paleozoic Depositional Trends in the 

Central Appalachian Basin

By KENNETH J. ENGLUND and ROGER E. THOMAS

A description of Carboniferous lithostratigraphy and 

paleogeography and an interpretation of terrestrial 

sedimentation and structural trends of the faulted and 

folded Appalachians

U.S. GEOLOGICAL SURVEY BULLETIN 1839 

EVOLUTION OF SEDIMENTARY BASINS-APPALACHIAN BASIN

CONTENTS

Abstract Fl 

Introduction Fl 

Geologic Setting F2 

Depositional Units F2

Faulted and Folded Appalachians F2

Mississippian and Pennsylvanian Rocks of the Cross-Section Area F5

Dunkard Basin F7 

Depositional Trends F7 

Conclusions F10 

References Cited F18

PLATE

1. Cross section of Mississippian and Pennsylvanian rocks in the central Appalachian 

basin [In pocket]

FIGURES

1. Map of the Appalachian basin showing the northwestward extent of terrestrial 

coal-bearing rocks in the Price, Bluestone, Pocahontas, and New River Formations and the strike of major structural trends in the faulted and folded 

Appalachians F3

2. Generalized stratigraphic cross section of the central Appalachian basin showing major unconformities and terrestrial coal-bearing rocks F4 

3-8. Maps showing:

3. Carter Caves Sandstone in northeastern Kentucky F9

4. Tallery Sandstone Member of the Hinton Formation on the southeastern 

side of the central Appalachian basin F10

5. Late Mississippian depositional environment Fll

6. Pocahontas No. 3 coal bed on the southeastern side of the Appalachian 

basin F12

7. Middle sandstone member of the Pocahontas Formation F13

8. Richlands channel as delineated by an isopach of underlying strata 

between the Jewell coal bed and the Dismal Sandstone Member of the 

New River Formation F14 

9. Cross section of the Richlands channel F15

10, 11. Maps showing generalized paleogeography during maximum terrestrial progradation in the:

10. Early Mississippian F16

11. Early Pennsylvanian F17

Contents III
CONVERSION FACTORS FOR SOME SI METRIC AND U.S. UNITS OF MEASURE

To convert from_____________To______________________Multiply by

Feet (ft) Meters (m) 0.3048

Miles (mi) Kilometers (km) 1.609

Pounds (Ib) Kilograms (kg) .4536

Degrees Fahrenheit (°F) Degrees (°C) Temp °C=(temp °F-32)/l.

IV Contents
EVOLUTION OF SEDIMENTARY BASINS-APPALACHIAN BASIN

Late Paleozoic Depositional Trends in the Central 

Appalachian Basin

By Kenneth J. Englund and Roger E. Thomas

Abstract

Trends in the regional extent, stratigraphic distribution, and character of upper Paleozoic terrestrial rocks in 

the central Appalachian basin were influenced by depositional events associated with basin evolution. Most of 

these rocks originated as siliciclastic detritus eroded from 

tectonic highlands that were elevated by plate collision 

along the southeastern margin of the basin. Terrestrial 

sediments, indicated by northwestward-prograding delta 

lobes and fluvial systems, were deposited in a slowly 

subsiding foreland basin. Concurrently, marine deposition encroached from the northwest in a shallow epicontinental sea that covered an unstable cratonic shelf. The 

transition from terrestrial to marine environments is evident in time-equivalent sequences of (1) fluvial and deltaic 

sandstone, (2) coal and related swamp deposits, (3) 

lagoonal and bay-fill shale, (4) barrier- and offshore-bar 

sandstone, and (5) marine limestone and shale. Terrestrial 

progradation extended northwestward during periods of 

high rainfall and sufficient subsidence to accommodate a 

high influx of clastic sediments. Conversely, marine incursions extended farthest southeastward during periods of 

diminishing rainfall and low clastic influx. When equilibrium existed between marine and terrestrial influences 

(that is, fluctuation from regression to transgression), the 

stillstand of sea level was accompanied by the development of widespread peat swamps and barrier or offshore 

bars. As the Appalachian basin evolved, terrestrial deposition gradually shifted northwestward and occupied the 

entire basin by Early Permian time. In addition, the strandline or wedgeout of terrestrial coal-bearing deposits 

rotated from N. 30° E. in Early Mississippian time to N. 65° 

E. in Early Pennsylvanian time. This change in the sedimentation pattern coincided with and possibly established 

the age of a similar rotation in the strike of deformed strata 

in the faulted and folded Appalachians, which may have 

resulted from plate rotation or multiple plate collisions.

Manuscript approved for publication May 18, 1989.

INTRODUCTION

The cross section presented in this report (pi. 1) 

extends through relatively flat lying Mississippian and 

Pennsylvanian rocks that underlie the Appalachian Plateaus 

of eastern Kentucky and southwestern Virginia. This 

traverse extends for 120 mi from northwest to southeast 

across most of the central Appalachian basin and is a 

compilation of data from 250 core holes, oil and gas tests, 

and surface sections. Geologic quadrangle maps provided 

additional information on the continuity and correlation of 

units between data points in eastern Kentucky and in part of 

southwestern Virginia. Reconnaissance geologic investigations were also sources of information, especially in the 

unmapped area.

Strata exposed along this traverse are mostly Pennsylvanian in age and represent the principal coal-bearing 

units in the Appalachian basin. Coal also occurs in older 

rocks of the faulted and folded Appalachians, southeast of 

the cross section, where peat accumulation began in the 

foreland basin in Late Devonian time and continued intermittently in Mississippian time. Peat deposits increased in 

extent and thickness as terrestrial sediments prograded 

northwestward across the foreland basin. By Early Pennsylvanian time, terrestrial sedimentation had extended into 

the area of the Appalachian Plateaus, and, by Middle 

Pennsylvanian time, it had extended across the cratonic 

shelf. Coal beds attained their maximum distribution, thickness, and quality in the Pennsylvanian sequence. These 

beds have been extensively mined during the past 100 years 

and continue to supply nearly one-half of the coal production in the United States, including as much as 90 percent of 

the output of high-grade metallurgical coal for domestic and 

export markets. The final stages of basin filling are recorded 

by terrestrial coal-bearing deposits of Early Permian age in 

the Dunkard basin northeast of the cross-section area. The 

coal beds in the Upper Devonian, Mississippian, and Lower 

Permian are of minor economic interest.

Late Paleozoic Depositional Trends in the Central Appalachian Basin F1
The purpose of this paper is to synthesize data on the 

distribution, lithofacies, and depositional environments of 

upper Paleozoic coal-bearing strata in the central Appalachian basin and to identify trends in basin evolution with a 

basinwide cross section.

GEOLOGIC SETTING

Coal-bearing strata in the central Appalachian basin 

are part of a sequence of terrestrial deposits ranging from 

Late Devonian to Early Permian in age. Although parts of 

this coal-bearing sequence are located beyond the area of 

the cross section and are older or younger than strata in the 

cross section (pi. 1), they are described briefly in order to 

present a more complete description of the geologic setting 

and to establish the duration and location of Late Paleozoic 

terrestrial deposition.

Mississippian and Pennsylvanian strata are preserved 

principally on the northwestern flank of the Appalachian 

basin, where they are relatively flat lying and underlie about 

190,000 mi2 of the Appalachian Plateaus (fig. 1). Correlative beds in the faulted and folded Appalachians to the 

southeast are moderately dipping and are discontinuously 

distributed in fault slices. A generalized stratigraphic cross 

section (fig. 2) based on a facies model (Englund and 

others, 1986b) shows that these late Paleozoic rocks occur 

in a southeast-thickening wedge in which the formations 

have an accumulative thickness of about 19,000 ft. There, 

rocks consist mostly of limestone, sandstone, siltstone, 

shale, coal, and underclay that are assigned to the following 

15 formations: the Hampshire Formation of Late Devonian 

and Early Mississippian age; the Price Formation, the 

Maccrady Shale, the Greenbrier Limestone, the Bluefield 

and Hinton Formations, and the Princeton Sandstone of 

Mississippian age; the Bluestone Formation of Late Mississippian and Early Pennsylvanian age; the Pocahontas, New 

River, and Kanawha Formations, the Charleston Sandstone, 

and the Conemaugh and Monongahela Formations of Pennsylvanian age; and the Dunkard Group of Late Pennsylvanian and Early Permian age (fig. 2). All of these formations 

contain or are interbedded with coal-bearing strata except 

for the Greenbrier Limestone.

DEPOSITIONAL UNITS

Descriptions of late Paleozoic rocks of the Appalachian basin are presented in ascending stratigraphic order 

for the following areas: (1) Upper Devonian and Mississippian rocks in the faulted and folded belt of the central 

Appalachian basin, (2) Mississippian and Lower and Middle Pennsylvanian rocks of the cross-section area (Appalachian Plateaus) (pi. 1), and (3) Middle and Upper Pennsylvanian and Lower Permian rocks of the Dunkard basin.

Faulted and Folded Appalachians

The oldest significant occurrence of coal and associated terrestrial deposits in the Appalachian basin is in the 

Hampshire Formation of Late Devonian and Early Mississippian age (Dennison and Wheeler, 1975, p. 71). Available data indicate that the coal is mostly impure and is 

limited to a few discontinuous beds, as much as 1 ft thick, 

in the upper part of the formation. The coal occurs in 

westward-prograding deltaic sequences of sandstone, 

grayish-red and greenish-gray shale, and siltstone that total 

more than 3,000 ft thick in the eastern part of the faulted 

and folded Appalachians. Although these coal occurrences 

are minor, they do indicate that the environment was 

favorable for land plants to flourish and for peat to accumulate in association with prograding terrestrial sediments 

of a slowly subsiding foreland basin. Similar depositional 

conditions continued throughout late Paleozoic time except 

for periodic uplifts and marine incursions that restricted the 

duration and extent of terrestrial deposition.

The upper part of the overlying Lower Mississippian 

Price Formation also includes a westward-prograding deltaic wedge and associated coal beds (fig. 2) (Englund, 

1979). This terrestrial wedge is as much as 375 ft thick in 

easternmost outcrops, where it contains 15 coal beds, 

including two widely recognized coal zones the Merrimac 

and the Langhorne. Each of those zones attains a maximum 

thickness of about 18 ft and includes several splits or beds 

of coal that range from a few inches to about 6 ft in 

thickness. These terrestrial deposits are distributed along 

the eastern edge of the basin, predominantly in the present 

Appalachian faulted and folded belt. A partly equivalent 

marine facies consisting mostly of prodeltaic sandstone and 

conglomeratic sandstone occupies the remainder of the 

formation. The Price Formation totals as much as 1,500 ft 

in thickness.

The succeeding Maccrady Shale is a lithically distinct 

red-bed sequence that consists of as much as 1,500 ft of 

grayish-red shale and siltstone sparsely interbedded with 

greenish-gray or gray plant-bearing shale, impure coal, and 

evaporite. The coal occurs in discontinuous beds up to a few 

inches in thicknesss. As the northwestward progradation of 

terrestrial elastics ceased in the Price Formation, probably 

in response to decreasing rainfall, the Maccrady was deposited over the abandoned deltaic systems of the Price in tidal 

flat and associated near-shore swamp environments.

The Greenbrier Limestone, at the base of the Upper 

Mississippian Series, represents the most widespread 

marine incursion during late Paleozoic time (Englund and 

others, 1986b). It discomformably overlies the Maccrady 

Shale and consists of as much as 1,500 ft of thick-bedded, 

very finely to coarsely crystalline limestone that is, in part, 

oolitic, cherty, or argillaceous. It thins northward and is

F2 Evolution of Sedimentary Basins Appalachian Basin
INDEX MAP

Figure 1 . Appalachian basin showing the northwestward extent of terrestrial coal-bearing rocks (shaded) in the Price (1), 

Bluestone (2), Pocahontas (3), and New River (4) Formations and the strike of major structural trends in the faulted and 

folded Appalachians.

absent in the northern part of the faulted and folded belt, 

where it has wedged out in a sequence of grayish-red shale 

and siltstone.

Although marine deposition was beginning to wane, 

it prevailed during the deposition of much of the overlying 

Bluefield Formation, which consists largely of gray, 

greenish-gray, and grayish-red, partly calcareous shale 

interbedded with limestone and argillaceous limestone. In 

easternmost exposures, the formation attains a maximum 

thickness of about 1,200 ft and includes wedges of sandstone, siltstone, coal, and underclay that were deposited 

during the initial seaward encroachments of terrestrial 

sediments in Late Mississippian time. These minor regressions in the Bluefield mark the beginning of a major 

regressive trend that accelerated in overlying units. Concurrently, the depositional environment for peat accumulation 

was improving, so that, by Early Pennsylvanian time, 

widespread peat deposits occupied the southeastern margin 

of the basin, as the extensive, high-quality Pocahontas coal 

beds indicate. In the Upper Mississippian formations,

Late Paleozoic Depositional Trends in the Central Appalachian Basin F3
NW

APPALACHIAN PLATEAUS

SE

FAULTED AND FOLDED 

APPALACHIANS

Dunkard Group

 Monongahela Formation 

'Conemaugh Formation 

" Cha "narleston Sandstone

Generalized land surface Kanawha Formation

Pocahontas Formation

Bluestone Formation 

Princeton Sandstone 

Hinton Formation

Bluefield Formation 

Greenbrier Formation

Maccrady Shale

" Price Formation 

Sunbury Shale 

Berea Sandstone 

Hampshire Formation 

(up to 3,000 ft)

SYSTEM

CARBO

Figure 2. Generalized stratigraphic cross section of the central Appalachian basin (based on Englund and others, 1986b) 

showing major unconformities (wavy lines) and terrestrial coal-bearing rocks (shaded), dashed where inferred. Extents of 

terrestrial sequences (1-4) are shown in figure 1.

known coal deposits are generally too thin and structurally 

unfavorable for conventional mining, but favorable areas 

for exploration have been recognized (Englund and others, 

1986a).

The Bluefield Formation is conformably overlain by 

the Hinton Formation, which is as much as 1,300 ft thick 

and is characterized by an abundance of grayish-red, partly 

calcareous shale and siltstone and includes lesser amounts 

of medium-gray and greenish-gray shale, sandstone, limestone, coal, carbonaceous shale, and rooted underclay. 

Exposed coal beds range from a few inches to 31 in thick 

and occur with shale containing fossil plants. The basal 

member of the Hinton Formation is a well-sorted quartzarenite that was deposited as a sequence of coalescing 

offshore bars (Englund and others, 1979). Shallow marine, 

tidal flat, deltaic, and freshwater swamp environments 

prevailed during the deposition of succeeding units of the 

Hinton (Englund and others, 1986b).

Locally, in the faulted and folded Appalachians, the 

Hinton is unconformably overlain by the Princeton Sandstone, which ranges from a polymictic conglomerate to a 

coarse conglomeratic subgraywacke as much as 60 ft thick. 

The matrix of the Princeton is light-gray, fine- to coarsegrained, thick-bedded to massive, calcite-cemented sandstone. Clasts in the formation are diverse in size and 

composition, are well rounded to angular, and include 

fragments derived from Devonian and Mississippian rocks 

(Cooper, 1961, p. 69). The age and variety of lithic 

fragments, ranging from locally derived limestone, shale, 

and siltstone to quartz and chert from distant sources, 

indicate the contemporaneity of Appalachian deformation. 

The Princeton was deposited on an eroded surface, possibly 

by storms and offshore currents associated with a marine 

incursion that continued during the deposition of the basal 

member of the overlying Bluestone Formation (Englund 

and others, 1986b).

The Bluestone Formation, which disconformably 

overlies the Hinton where the Princeton is absent, consists 

of six members that total as much as 850 ft in thickness. 

Except for an overall decrease in marine influence, the

F4 Evolution of Sedimentary Basins Appalachian Basin
lithology and depositional environments of the Bluestone 

Formation are similar to those of the Hinton. The basal 

Pride Shale Member is mostly dark-gray shale and silty 

shale that contain marine and brackish-water faunal assemblages, fossil plants, and vertebrates. Where it overlies the 

Princeton Sandstone, the lower part includes a wedge of 

greenish-gray and grayish-red shale and one or two thin coal 

beds. The Pride represents a shallow embayment or lagoon 

infilling that is overlain by the regressive and probably 

deltaic Glady Fork Sandstone Member (Englund and others, 

1986b). Overlying the Glady Fork and merging with the 

underlying Pride beyond the extent of the Glady Fork is a 

major progradation of terrestrial coal-bearing strata 

assigned to the gray member. In addition to several thin coal 

beds, the gray member contains carbonaceous shale and 

freshwater or brackish-water ostracodes and pelecypods. 

The overlying red member is a tidal flat sequence of mostly 

grayish-red, partly calcareous shale and siltstone and a few 

beds of nodular argillaceous limestone (Englund and others, 

1981). It also includes freshwater swamp deposits, as 

several thin beds of coal and underclay indicate. The 

Bramwell Member, the youngest Mississippian unit in the 

Bluestone, was deposited during marine transgression 

across the lower coastal plain underlain by the red member. 

At the base of the Bramwell, carbonaceous shale containing 

freshwater and brackish-water faunas grades upward to silty 

shale and calcareous siltstone that include sparse, thin 

limestone beds and a highly diverse marine fauna. The 

overlying upper member of the Bluestone Formation contains an Early Pennsylvanian flora and consists of prodeltaic 

greenish-gray and grayish-red shale that overlapped the 

basal deltaic lobes of the Pocahontas Formation.

Mississippian and Pennsylvanian Rocks of the 

Cross-Section Area

The Mississippian sequence in the cross section (pi. 

1) includes formations exposed in the faulted and folded 

Appalachians plus two additional formations the Berea 

Sandstone and the Sunbury Shale (fig. 2). The principal 

variations noted in the lithology and thickness of these strata 

in the Appalachian Plateaus are emphasized in the following 

unit descriptions.

The Berea Sandstone, at the base of the Lower 

Mississippian Series, crops out in three widely separated 

areas of the central Appalachian basin: (1) an outcrop belt 

near the northwestern terminous of the cross section, (2) the 

northwestern slope of Pine Mountain near the KentuckyVirginia State line, about 15 mi southwest of the cross 

section, and (3) near the southeastern terminous of the cross 

section. In the northwestern outcrop belt, the Berea is a 

thin- to thick-bedded, very fine grained to fine-grained 

sandstone as much as 100 ft thick (Morris, 1966). In the 

Pine Mountain outcrop belt, the Berea is an evenly bedded,

very fine grained, quartzose sandstone about 50 ft thick 

(Alvord and Miller, 1972). At the southeastern edge of the 

plateaus in Tazewell County, Virginia, the Berea crops out 

only locally. There it is a thick-bedded to massive, fine- to 

coarse-grained, conglomeratic sandstone about 5 ft thick 

(Windolph, 1988). Elsewhere along the southeastern edge 

of the plateaus, the Berea is absent, and the Sunbury Shale 

or its correlative, the Big Stone Gap Member of the 

Chattanooga Shale, rests directly on the Chemung Formation of Devonian age (Englund, 1968; Englund and others, 

1979). Descriptions of the Berea from oil and gas tests 

indicate that the lithology and thickness in the subsurface 

are similar to those noted in outcrop observations. Berea 

sediments in the cross-section area were derived from an 

eastern source and deposited in an epicontinental sea by 

several westward-flowing rivers (deWitt and McGrew, 

1979).

The Sunbury Shale conformably overlies the Berea 

Sandstone and has a similar distribution and outcrop pattern. It is a black, evenly bedded, highly carbonaceous 

shale that ranges from about 15 ft thick at the northwestern 

end of the cross section to 55 ft in the outcrop belt at the 

southeastern edge of the Appalachian Plateaus. In southwestern Virginia and southern West Virginia, the Sunbury is 

also known as the Big Stone Gap Member of the Chattanooga Shale and is more extensive than the Berea. A 

shallow, stagnant sea occupied the central Appalachian 

basin during Sunbury deposition (Pepper and others, 1954).

The Sunbury Shale along the southeastern edge of the 

Appalachian Plateaus is conformably overlain by a 

sequence of conglomeratic sandstone, sandstone, and shale 

of the Price Formation. Marine invertebrates are common in 

the sandstone in the lower part of the formation; terrestrial 

beds, including one or two thin coal beds, are present 

locally in the uppermost part of the formation. Northwestward across the plateaus, the Sunbury is overlain by the 

Lower Mississippian Grainger Formation in southwestern 

Virginia and the Borden Formation in eastern Kentucky. 

These correlatives of the Price are entirely marine and 

consist of shale, silty shale, siltstone, and very fine grained 

sandstone. Marine invertebrates, including brachiopods, 

crinoids, and bryozoans, are locally abundant in these beds. 

Thicknesses range from about 600 ft at the southeastern and 

northwestern edges of the Appalachian Plateaus to a minimum of about 350 ft over the Waverly arch (pi. 1).

The Maccrady Shale consists of 30 to 150 ft of 

grayish-red shale and siltstone and minor amounts of 

sandstone and dolomite where it conformably overlies 

terrestrial coal-bearing beds in the upper part of the Price 

Formation at the southeastern edge of the Appalachian 

Plateaus. Northwestward in the subsurface and along Pine 

Mountain, correlatives of the Maccrady consist mostly of 

siltstone and sandstone within this thickness range and are 

known to drillers as the Red Injun sand. At the northwestern 

end of the cross section (pi. 1), as much as 60 ft of

Late Paleozoic Depositional Trends in the Central Appalachian Basin F5
grayish-red and greenish-gray shale and siltstone in the 

upper part of the Borden Formation may be its correlative.

The Greenbrier Limestone and equivalents extend 

throughout the subsurface of the Appalachian Plateaus and 

crop out at the northwestern and southeastern margins and 

locally at uplifted structures in the intervening area. The 

Greenbrier disconformably overlies the Maccrady Shale or 

the Price Formation and, in places, includes a basal conglomerate of well-rounded quartz and chert pebbles. The 

lithology of the Greenbrier is similar to that of the faulted 

and folded Appalachians, and its thickness decreases northwestward from 800 to 0 ft, owing partly to the erosion of 

beds along overlying unconformities. Pre-Pennsylvanian 

subareal weathering and sinkhole development are also 

significant features that decrease the thickness of the Greenbrier (Slade Formation at the Kentucky outcrop) on the 

uplifted southeastern flank of the Cincinnati arch (Englund 

and Windolph, 1971).

The overlying Upper Mississippian sequence is 

assigned to the Bluefield, Hinton, and Bluestone Formations and consists predominantly of shale, limestone, and 

sandstone of marine origin. Intercalated terrestrial wedges 

containing thin coal beds are confined to the southeastern 

edge of the Appalachian Plateaus. The Upper Mississippian 

formations are truncated northwestward at the Lower Pennsylvanian unconformity and are absent where the cross 

section transects the Waverly arch (Englund, 1972). Remnants of the Bluefield and possibly the Hinton are preserved 

beneath the unconformity in a shallow trough between the 

Waverly and Cincinnati arches (Englund and Henry, 1984).

The Bluefield Formation at the base of the Upper 

Mississippian clastic sequence conformably overlies the 

Greenbrier Limestone. It consists largely of shale and 

limestone containing marine fossils. Sandstone is more 

common in the succeeding Hinton Formation, where it 

varies from very fine grained and ripple bedded in the basal 

Stony Gap Sandstone Member to coarse grained, conglomeratic, and massive in the uppermost Tallery Sandstone 

Member. The thickest and most widely recognized marine 

unit in the Hinton, the Little Stone Gap Member, is 

fossiliferous limestone and calcareous shale that total as 

much as 100 ft thick.

The succeeding Princeton Sandstone wedges out 

along the disconformity at the top of the Hinton in the 

eastern part of the Appalachian Plateaus. As a result, it is 

absent in the cross section, and the Hinton Formation is 

disconformably overlain by the Pride Shale Member of the 

Bluestone Formation. The members of the Bluestone are 

lithically similar to their counterparts in the faulted and 

folded Appalachians. An exception is the wedgeout of 

terrestrial coal-bearing beds, including the gray member, in 

the easternmost part of the plateaus, owing to a westerly 

increase in marine influences.

Clastic coal-bearing strata assigned to the Lower 

Pennsylvanian Pocahontas Formation conformably overlie

the Bluestone Formation in its eastern exposures. The 

Pocahontas Formation consists mostly of sandstone and 

lesser amounts of siltstone, shale, coal, and underclay that 

prograded northwestward in a series of merging delta lobes 

and associated near-shore deposits. Periodic abandonment 

of these major distributary systems permitted the development of extensive swamps and thick peat deposits that were 

precursors of the principal coal beds, including the Pocahontas Nos. 3, 4, and 6, in the formation. These peat 

accumulations coincided with stillstands of sea level when a 

minimal influx of sediments and a stable shoreline allowed 

waves and currents to form barrier systems consisting of 

lithically and texturally mature quartz sand (Englund and 

others, 1986a). From a maximum thickness of about 700 ft 

at the southeastern edge of the Appalachian Plateaus, the 

Pocahontas Formation thins northwestward and wedges out 

in a distance of about 30 mi. Where the formation is 

thickest, the contact with the overlying New River Formation is conformable at the base of the Pocahontas No. 8 coal 

bed. The wedging out of the Pocahontas Formation results, 

in part, from the truncation of upper beds at the Lower 

Pennsylvanian unconformity at the base of the Pineville 

Sandstone Member of the New River Formation.

The New River Formation and the partially correlative Lee Formation underlie the Appalachian Plateaus and 

range in thickness from nearly 2,000 ft on the southeastern 

side to less than 100 ft on the northwestern side. These 

formations are coal-bearing sequences of sandstone, siltstone, shale, and underclay that are lithically similar to the 

Pocahontas Formation except for the presence of thicker 

and more widespread barrier or offshore bars of quartzpebble conglomerate and orthoquartzite (Englund and others, 1986b). The latter units onlap the Lower Pennsylvanian 

unconformity and are progressively younger to the northwest. In general, the Pocahontas coastal depositional model 

is applicable to the larger scale features of the New River. 

Beds in the sequence that contain marine fossils are more 

prevalent to the northwest. Also, in association with the 

overall shift of facies to the northwest, fluvial deposition 

encroached from the southeast to dominate the southeastern 

or terrestrial facies of the New River Formation. The 

southeastern facies is also characterized by as many as 15 

economically important coal beds.

The principal difference between the New River and 

the Lee Formations regionally is in the placement of the top 

contact. The uppermost member of the New River is the 

Nuttall Sandstone Member in West Virginia or its correlative, the McClure Sandstone Member in Virginia. More 

specifically, the top contact of the New River is placed at 

the base of the Douglas coal bed or its correlative, the 

Kennedy coal bed, both of which overlie a thin underclay 

bed at the top of the sandstone member. Where the 

uppermost sandstone member is absent or thin and inconspicuous, the top contact of the New River, which is also 

the top boundary of the Lower Pennsylvanian Series,

F6 Evolution of Sedimentary Basins Appalachian Basin
continues essentially as a chronostratigraphic boundary at 

the base of the Kennedy or Douglas coal bed. In contrast, 

the upper contact of the Lee Formation is placed at the top 

of the uppermost orthoquartzite, which, in places, may be 

several hundred feet below or above the Kennedy-Douglas 

coal bed (pi. 1). Regionally, the upper contact of the Lee is 

diachronous and rises stratigraphically to the northwest 

(Englund, 1962). The Lee Formation at the northwestern 

end of the cross section (pi. 1) therefore includes beds of 

Middle Pennsylvanian age.

Middle Pennsylvanian strata overlying the New River 

and the Lee Formations in the upper part of the cross section 

(pi. 1) are identified by several different nomenclatures. In 

adjoining parts of Virginia and West Virginia where the 

New River is recognized, these overlying rocks are assigned 

to the Kanawha Formation. To the southwest in Virginia, 

where the Lee Formation is identified, they are included in 

the Norton Formation, the Gladeville Sandstone, and the 

Wise Formation. In eastern Kentucky, they are included in 

the Breathitt Formation. The Middle Pennsylvanian 

sequence is more than 2,000 ft thick and consists mostly of 

medium- to dark-gray shale and siltstone, fine- to mediumgrained sandstone, coal, and underclay. These beds are 

largely terrestrial and occur in deltaic and fluvial systems 

that are intercalated with several widespread marine beds. 

In contrast to the thick beds of conglomeratic quartzose 

sandstone that are typical of the New River and the Lee, 

those of the Middle Pennsylvanian are subgraywackes that 

tend to be thinner, finer grained, feldspathic, and micaceous 

and have a relatively low quartz content of about 50 to 65 

percent.

Dunkard Basin

The Dunkard basin, located about 75 mi northeast of 

the cross section (pi. 1), contains the youngest terrestrial 

coal-bearing rocks of the Appalachian basin. The coal 

occurs in a largely red-bed sequence that is subdivided into 

the Conemaugh and Monongahela Formations of Late 

Pennsylvanian age and the Dunkard Group of Late Pennsylvanian and Early Permian age. In the underlying Middle 

Pennsylvanian Series, the Kanawha Formation and the 

Charleston Sandstone are also coal bearing and lithically 

similar to correlative beds shown in the upper part of the 

cross section (pi. 1).

The Conemaugh Formation, at the base of the Upper 

Pennsylvanian Series, includes as much as 500 ft of strata 

from the top of the Upper Freeport coal bed to the base of 

the Pittsburgh coal bed. The Conemaugh is characterized by 

an abundance of grayish-red shale or clay stone, which is the 

basis for differentiating the formation from underlying 

strata where the Upper Freeport coal bed is absent or 

unidentified. In the southern part of the Dunkard basin, the 

Conemaugh consists of about 60 percent grayish-red,

greenish-gray, and variegated shale and claystone, 30 percent sandstone, and 10 percent gray shale, nonmarine 

limestone, flint clay, and coal. The percentage of grayishred beds decreases toward the northwestern part of the 

basin, where gray beds, which include a few marine 

limestone units, are prevalent. Sandstone beds are thicker, 

more massive, and locally conglomeratic to the southeast. 

The Conemaugh, together with other Upper Pennsylvanian 

strata, were deposited in association with a delta complex 

system that prograded westward and northward in the 

foreland basin onto the craton (Donaldson, 1979). The 

deltas were fluvial dominated and were fed by suspended 

load rivers. Extensive lakes developed as the 

northwestward-prograding streams restricted or sealed the 

narrow bay that extended northeastward into the Dunkard 

basin. Coal beds in the Conemaugh are relatively high in 

sulfur and ash and tend to be thicker and more persistent to 

the northwest in the facies dominated by gray shale.

The succeeding Monongahela Formation is lithically 

similar to the Conemaugh and is also characterized by an 

abundance of grayish-red, greenish-gray, and variegated 

mudstone and lesser amounts of very fine grained to 

fine-grained sandstone, gray shale, carbonaceous shale, 

coal, and nonmarine limestone. The coal beds, with the 

exception of the economically important Pittsburgh coal at 

the base of the formation, are also relatively thin, lenticular, 

and high in ash and sulfur. The Monongahela was deposited 

as part of the fluvial-dominated northwestward-prograding 

delta systems that originated in the Conemaugh. Marine 

beds are absent in the late Paleozoic sequence above the 

Conemaugh. The thickness of the Monongahela ranges 

from about 200 to 400 ft.

The overlying Dunkard Group of Late Pennsylvanian 

and Early Permian age consists of as much as 1,300 ft of 

largely grayish-red claystone, shale, and siltstone and lesser 

amounts of interbedded sandstone, limestone, and coal. 

These strata include the youngest Paleozoic rocks in the 

basin and are limited in distribution mostly to the Dunkard 

basin in the adjoining areas of northern West Virginia, 

southeastern Ohio, and southwestern Pennsylvania. Coal in 

the Dunkard is high in sulfur and ash, and most of the beds 

are thin and discontinuous. Of the 20 coal beds in the 

Dunkard, only the Waynesburg and Washington coal beds 

have been mined to a significant extent. During deposition, 

a fluvial-dominated deltaic system prograded from the 

southeast in association with fluctuating lacustrine, fluvial 

plain, and coal swamp environments. Climatic variations 

including seasonal rainfall contributed to the periodic flood 

of detritus that resulted in the deposition of broad, fluvialdelta plains. During periods of stability, swamps covered 

large parts of the basin.

DEPOSITIONAL TRENDS

Late Paleozoic rocks in the central Appalachian basin 

display lateral and vertical trends in the relation of terrestrial

Late Paleozoic Depositional Trends in the Central Appalachian Basin F7
to marine deposits and in the distribution and character of 

coal beds. The first occurrence of coal in the upper part of 

the westward-prograding Catskill delta complex (Hampshire Formation) records the deposition of peat in association with westward-prograding terrestrial clastic sediments 

and established a trend that followed during later Paleozoic 

time. Because the upper coal-bearing part of the Hampshire 

very likely includes beds of Early Mississippian age (Dally, 

1956; Englund and others, 1988), the contemporaneous 

tectonic uplift and shedding of elastics from the Appalachian positive element to the southeast may have been in 

response to Late Devonian and Early Mississippian plate 

collision (Ettensohn, 1985). Marine deposition prevailed in 

the fringe of the Catskill delta complex and continued on the 

cratonic shelf to the west throughout Early Mississippian 

time. This sequence is represented by the Berea Sandstone, 

Sunbury Shale, and Borden or Price Formations in the cross 

section (pi. 1).

The surge of terrestrial clastic sediments during the 

deposition of the upper part of the Price Formation follows 

the trend of Hampshire distribution in the faulted and folded 

Appalachians. The Price terrestrial unit includes thicker and 

more widespread coal beds and extends further to the west, 

so that its distal end encroaches locally into the margin of 

the Appalachian Plateaus north of the southeastern end of 

the cross section (pi. 1). Deltaic deposition was interrupted 

periodically, and peat accumulated in broad, back-barrier, 

lagoonal swamps (Englund, 1979). The fact that the coal is 

mostly low in sulfur (less than 0.5 percent) (Simon and 

Englund, 1983) may reflect the lack of marine incursions or 

a decrease in sulfur associated with diagenesis, which is 

common in many high-rank coal beds. In contrast, this coal 

is high in ash (greater than 15.0 percent) and contains 

numerous partings that may have resulted from clastic 

sedimentation during flood periods. The highly sheared 

condition of the coal may also have been a factor that 

increased the ash content by introducing contaminants along 

shear planes. Waning terrestrial deposition, indicated by a 

few thin coal beds in the basal part of the overlying 

Maccrady Shale, was followed by a major marine incursion. The maximum extent of marine incursion was attained 

during the time when the succeeding Greenbrier Limestone 

was deposited. During the deposition of the overlying 

Bluefield Formation, marine conditions began to regress, 

and terrestrial deposition (including peat) occurred on the 

southeastern margin of the basin. The northwestward progradation of terrestrial clastic sediments continued throughout Late Mississippian time, mostly in the foreland basin. 

The distal ends of the Late Mississippian terrestrial facies 

extended locally into the southeastern part of the Appalachian Plateaus, including the area of the southeastern end of 

the cross section (pi. 1). Upper Mississippian coal-bearing 

rocks therefore extend about 15 mi further northwest than 

similar strata in the Lower Mississippian (fig. 2). Also, the 

strike of the leading edge or strandline has rotated from

about N. 30° E. in Early Mississippian time to N. 40° E. in 

Late Mississippian time, a reflection of a gradual southwestward increase in the uplift of the source area in the 

Appalachian uplands.

Mississippian depositional trends indicate that the 

Appalachian seaway slowly regressed northwestward on the 

craton in a series of regressive-transgressive events and 

included several barrier and offshore bars of orthoquartzite. 

Examples of these marine features are shown by the Carter 

Caves Sandstone (fig. 3) on the northwestern side of the 

basin and by the Tallery Sandstone Member of the Hinton 

Formation (fig. 4) on the southeastern side of the basin. A 

paleogeographic reconstruction of the Appalachian basin 

(Craig and others, 1979) indicates the relation of these 

sandstone bars to peat deposits along the southeastern 

margin of the basin (fig. 5). When rainfall increased during 

the deposition of overlying Pennsylvanian sediments (Cecil 

and others, 1985), the supply of coarse elastics increased, 

and such deposits became more extensive.

By Early Pennsylvanian time, terrestrial coal-bearing 

sediments of the Pocahontas Formation dominated the 

east-central Appalachian basin. The earliest Pennsylvanian 

sediments consisted of sand, which accumulated in the 

major distributary channels and lobes. A decrease in grain 

size and the orientation of the lobes show that elastics 

prograded northwestward from a southeasterly source, continuing (with minor modification) the trend established in 

underlying Mississippian strata. At the top of the lower 

sandstone member of the Pocahontas Formation, sand 

graded to silt and clay before the accumulation of peat, as 

recorded by 3 to 6 ft of coal. This peat deposit coincided 

with a stillstand of the shoreline and a period of minimal 

influx of clastic sediments (Englund and others, 1986a). 

Along the stabilized shoreline, the reworking of sediments 

by wave and current action led to the development of a 

barrier system consisting of lithically and texturally mature 

sand. Delta progradation resumed in the middle sandstone 

member of the Pocahontas. Within this interval, local peat 

formation associated with delta lobe switching is indicated 

by the discontinuous Pocahontas Nos. 1,2, and 2A coal 

beds. When the distributary systems of the middle sandstone member were abandoned, clastic sedimentation 

ceased, and an extensive peat deposit, represented by the 

Pocahontas No. 3 coal bed, accumulated on the delta lobes. 

The Pocahontas No. 3 coal bed, the thickest and most 

widely distributed of the Pocahontas coal beds, attained 

thicknesses of 3 to 9 ft over large areas (fig. 6). Variations 

in the thickness and quality of the coal indicate that the 

thickest, low-ash and low-sulfur coal is situated over the 

abandoned distributary lobes (Englund and others, 1984). 

This distribution of thick, high-quality coal was influenced 

by (1) initial and optimum growth of vegetation on the 

relatively positive high-sand lobes, (2) deposition of thin 

peat or carbonaceous shale in the greater compactible 

shale-dominated fringe or interlobe areas, and (3) high

F8 Evolution of Sedimentary Basins Appalachian Basin
I

83°

5 MILES

8 KILOMETERS

Conglomeratic 

orthoquartzite

Isopach of

orthoquartzite

(contour interval 20 ft)

38° 30'-

38° 15'-

FEET METERS

£H 100- 30

0 1,000 2,000 3,000 METERS

Figure 3. Carter Caves Sandstone in northeastern Kentucky (from Englund and Windolph, 1971). Patterns in cross 

section are the ones used in plate 1.

Late Paleozoic Depositional Trends in the Central Appalachian Basin F9
WEST 

VIRGINIA

EXPLANATION

Conglomeratic orthoquartzite

Isopach of orthoquartzite 

(contour interval 50 ft)

KENTUCKY

38°-

ta

Outcrop of Tallery 

Sandstone Member 

of Hinton Formation

Location of 

Russell Fork fault 37°-

VIRGINIA^ 

TENNESSEE

I h 10 MILES

16 KILOMETERS

81°

Figure 4. Tallery Sandstone Member of the Hinton Formation on the southeastern side of the central Appalachian basin 

(restored to original location at the Rocky Face and Russell Fork faults).

rainfall that contributed to the preservation of domed 

deposits of ombrogenous peat (England and others, 1986a). 

These deltaic lobes (fig. 7) are oriented normal to the strike 

of the leading edge or strandline of these earliest Pennsylvanian terrestrial strata, which is about N. 45° E.

In the overlying New River Formation, offshore or 

barrier bars of quartzarenite and quartz-pebble conglomerate are thicker and more widespread. Deposition occurred in 

a high-energy tidal environment (Cecil and Englund, 1985). 

These sandstone units continue to be oriented parallel to the 

southeastern shoreline and wedged out southeastward in a 

back-barrier sequence containing as many as 36 coal beds. 

Because of the northwestward shift of the shoreline and 

associated sediments, fluvial sediments began to encroach 

on the craton from the southeast.

An example of fluvial sedimentation in the backbarrier sequence is the Richlands channel (Englund and 

Thomas, 1985), which extended about 30 mi northwestward from Richlands, Va., and truncated as much as 130 ft 

of underlying coal-bearing strata, as the isopach of underlying beds in figure 8 shows.

As cross section A-A' (fig. 9) shows, the channel is 6 

mi wide and filled with sandstone and polymictic conglomerate. Clasts in the channel are well rounded and as much as

5 in in diameter and consist mostly of quartz. The Richlands 

channel and other channels in the New River Formation 

demonstrate that Pennsylvanian elastics originated from the 

southeast and were transported N. 25° W. normal to the 

strandline (fig. 1).

As northwestward regression continued in Middle 

Pennsylvanian time, terrestrial coal-bearing sediments gradually dominated the Appalachian basin, and marine incursions were limited mostly to the northwestern part of the 

basin by Late Pennsylvanian time.

During the final stages of basin filling, when the 

Conemaugh and Monongahela Formations and the Dunkard 

Group were laid down, rainfall became seasonal (Cecil and 

others, 1985) but continued to contribute periodic floods of 

detritus that prograded northwestward and sealed a narrow 

bay, a remnant of the Appalachian seaway that occupied the 

central part of the basin. As a result, lakes and swamps 

developed between the fluvial systems, and red beds, 

nonmarine limestone, and a few high-ash and high-sulfur 

peat beds were deposited.

CONCLUSIONS

A significant change in basin sedimentation patterns 

in late Paleozoic times is indicated by progradation trends

F10 Evolution of Sedimentary Basins Appalachian Basin
allery Sandstone Member 

of Hinton Formation

EXPLANATION 

Swamp 

Current direction

100 200 MILES

1 T

300 KILOMETERS

Figure 5. Late Mississippian depositional environment (modified from Craig and others, 1979). Carter Caves Sandstone 

and Tallery Sandstone Member are plotted to scale.

and by the northwestward extent of terrestrial coal-bearing 

rocks. The extent or wedgeout of terrestrial units in the 

Price, Bluestone, Pocahontas, and New River Formations 

(fig. 2) shows that the northwestward shift of the coalbearing facies in late Paleozoic time is accompanied by a 

rotation of the strike of the wedgeout from N. 30° E. in 

Lower Mississippian strata to N. 65° E in Lower Pennsylvanian strata (fig. 1). The location and magnitude of this 

change in the sedimentation trend correspond closely to the 

change in the structural trend in the faulted and folded 

Appalachians that separates the predominantly folded Appalachians (N. 30° E.) to the northeast from the predominantly 

faulted Appalachians (N. 65° E.) to the southwest. The 

close association and parallelism of the sedimentation and 

structural trends indicate that:

1. Deformation associated with plate collision began in 

Early Mississippian or Late Devonian time.

2. Folding and deposition in the Appalachians were synchronous, at least in late Paleozic time (Cooper, 1961).

3. Deformation began northeast of the rotation point and 

later increased to the southwest, possibly as a result of

Late Paleozoic Depositional Trends in the Central Appalachian Basin F11
V 

WEST

*) VIRGINIA /

KENTUCKY

Strike-slip fault 

arrows indicate relative 

horizontal movement)

Eastern margin of

Appalachian

coal basin

Isopach of

Pocahontas No. 3 coal bed 

(contour interval 14 in)

0 5 10 MILES I I I

0 8 16 KILOMETERS

Figure 6. Pocahontas No. 3 coal bed on the southeastern side of the Appalachian basin (from Englund and others, 1986a).

plate rotation or multiple plate collisions such as that of 

the European plate to the northeast (fig. 10) and the 

African plate to the southeast (fig. 11). 

Changes in the structural trend occurred primarily in 

latest Mississippian and earliest Pennsylvanian time. 

The southwestward rotation in the structural trend may 

be responsible for the temporary opening of the Appalachian seaway (fig. 11) to the northeast during Early

Pennsylvanian time, which permitted strong southwestflowing tidal currents to erode earlier Pennsylvanian and 

Late Mississippian sediments on the cratonic shelf 

(Lower Pennsylvanian unconformity); the deposition of 

coarse clastic sediments (pebbly sand) by high-energy 

tidal currents, similar to the processes observed in the 

Straits of Malacca (Cecil and others, 1988), followed in 

later Early Pennsylvanian time.

F12 Evolution of Sedimentary Basins Appalachian Basin
WEST VIRGINIA

KENTUCKY

EXPLANATION

>100ft 

0-100 fl

Thickness of middle sandstone member

of Pocahontas Formation

Strike-slip fault 

arrows indicate relative 

horizontal movement)

Eastern margin of

Appalachian

coal basin

Isopach of

middle sandstone member

of Pocahontas Formation

(contour interval 25 ft)

0 8 16 KILOMETERS

Figure 7. Middle sandstone member of the Pocahontas Formation (from Englund and others, 1986a).

Late Paleozoic Depositional Trends in the Central Appalachian Basin Fl 3
81°45'

EXPLANATION

 Data point

700 Isopach (interval 25 ft)

Thrust fault (sawteeth on upper plate)

Strike-slip fault (arrows indicate 

relative horizontal movement)

Rocks older than 

Pennsylvanian

37°07'30"

Figure 8. Richlands channel as delineated by an isopach of underlying strata between the Jewell coal bed and the Dismal 

Sandstone Member of the New River Formation. Cross section A-A' is shown in figure 9.

F14 Evolution of Sedimentary Basins Appalachian Basin
DATA POINTS

I I I 

SW

100 FT -i

Underclay Coal

8 KILOMETERS

Figure 9. Cross section of the Richlands channel (shown in fig. 8).

Late Paleozoic Depositional Trends in the Central Appalachian Basin F15
EXPLANATION 

Swamp

Current direction

100 200 MILES _]____I i I r

300 KILOMETERS

Figure 10. Generalized Early Mississippian paleogeography during maximum terrestrial progradation. Dashed lines 

indicate the underwater portion of the Appalachian positive element.

F16 Evolution of Sedimentary Basins Appalachian Basin
Figure 11. Generalized Early Pennsylvanian paleogeography during maximum terrestrial progradation. Dashed lines 

indicate the underwater portion of the Appalachian positive element.

Late Paleozoic Depositional Trends in the Central Appalachian Basin F17
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Late Paleozoic Depositional Trends in the Central Appalachian Basin F19