Silurian Nomenclature and 

Correlations in Southwest 

Virginia and Northeast 

Tennessee

GEOLOGICAL SURVEY BULLETIN 1405-H

Silurian Nomenclature and 

Correlations in Southwest 

Virginia and Northeast 

Tennessee

By RALPH L. MILLER

CONTRIBUTIONS TO STRATIGRAPHY

GEOLOGICAL SURVEY BULLETIN 1405-H

Establishes a reference section for the Clinch Sandstone, extends the name 

Rose Hill Formation to southwest Virginia and northernmost Tennessee, 

and clarifies the relations between the Clinch Sandstone, 

Rose Hill Formation, and Rockwood Formation

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1976
UNITED STATES DEPARTMENT OF THE INTERIOR 

THOMAS S. KLEPPE, Sccretaty

GEOLOGICAL SURVEY 

V. E. McKelvey, Director

Library of Congress Cataloging in Publication Data

Miller, Ralph LeRoy, 1909-

Silurian nomenclature and correlations in southwest Virginia and northeast Tennessee.

(Contributions to stratigraphy)

(Geological Survey Bulletin 1405-H)

Bibliography: p. 23-25.

Supt.ofDocs.no.: I 19.3:1405-H

1. Geology, Stratigraphic Silurian. 2. Geology, Stratigraphic Nomenclature Virginia. 3.

Geology, Stratigraphic Nomenclature Tennessee. 4. Stratigraphic correlation Virginia.

Geological Survey Bulletin 1405-H. 

QE75.B9 no. 1405-H [QE66] 550'.8s[551.7'32'097557] 75-619502

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

Washington, D. C. 20402

Stock Number 024-001-02787-9
CONTENTS

Page

Abstract __________________________________________ HI

Introduction______________________________________________ 2

Acknowledgments _______________________________________ _ 2

Regional setting_______________________________________ ______ 3

Origin and usage of formation names ___________________________ ______ 3

Clinch Sandstone ______________________________________ 3

Clinton Formation-Rose Hill Formation _________________________ 5

Rockwood Formation _______________________________________ 7

Clinch Sandstone ______________________________________________ 7

Clinch Mountain belt and reference section ________________ ___ _ 7

Ridges west and north of Clinch Mountain ______________________ H

Age 14

Rose Hill Formation __________________________________________ ^5

Rockwood Formation __________________________________________ ^5

Big Ridge belt____________________________________________________ IQ

Dutch Valley belt ______________________________________ 21

Poor Valley Ridge belt ____________________________________________ 21

Elk Valley belt _________________________________________________ 22

Regional application of Silurian formation names ____________________ 22

Summary _________________________________________________ 23

References cited _____________________________________________ 23

ILLUSTRATIONS

Page

FIGURE 1. Map of southwest Virginia and northeast Tennessee ______________ H4

2. Restored section along the lineA-A' (fig. 1) _________________ jg

3. Restored section along the lineB-B' (fig. 1) _________________ 20

TABLES

Page

TABLE 1. Clinch Sandstone along roads crossing Clinch Mountain, Va. and Tenn. H12 

2. Silurian clastic formations at selected localities in southwest Virginia 16 

and northeast Tennessee ______________________________

III

SILURIAN NOMENCLATURE AND

CORRELATIONS IN SOUTHWEST

VIRGINIA AND NORTHEAST TENNESSEE

By RALPH L. MILLER

ABSTRACT

Silurian clastic formations in southwest Virginia and northeast Tennessee have been 

named Clinch Sandstone, Clinton Formation, and Rockwood Formation. In Lee County, 

Va., and adjacent areas, two members of the Clinch have been mapped, a lower Hagan 

Shale Member and an upper Poor Valley Ridge (sandstone) Member.

The Clinch Sandstone takes its name from Clinch Mountain, a prominent ridge 140 

miles (225 km) long in Tennessee and Virginia. Although the formation has been 

recognized and mapped in both States for more than 100 years, until very recently no 

type section was ever designated. Sections of the formation were examined along all 

roads that cross the mountain, and excellent exposures were found at Little Moccasin 

Gap, Washington County, Va. As a type section has now been described in east 

Tennessee, the Virginia section is here designated a reference section and is described.

Overlying the Clinch Sandstone in southwest Virginia and northeast Tennessee is a 

clastic sequence, predominantly shale, of Middle Silurian age, that has been called the 

Clinton Formation, from a location in central New York. In western Maryland, however, 

a sequence of the same age and similar lithology is named the Rose Hill Formation, and 

this name is in general use for these beds in West Virginia and in parts of western 

Virginia. In west-central Virginia, the name Cacapon Sandstone Member of the Clinton 

Formation has also been applied to a sequence approximately equivalent to the Rose Hill 

Formation, but the Middle Silurian rocks of southwest Virginia more closely resemble 

the Rose Hill Formation than they do the more sandy Cacapon.

Because of the remoteness of the type area of the Clinton Group from southwest 

Virginia and northeast Tennessee and the intervention of an established and extremely 

well documented alternative name for the beds in question, the name Clinton Formation 

should be dropped in southwest Virginia and northeast Tennessee in favor of Rose Hill 

Formation.

The Clinch Sandstone is of Early Silurian age in the outcrop belts in Lee County, Va., 

but in Clinch Mountain, beds of early Middle Silurian age may be included at the top. 

The Rose Hill Formation is Middle Silurian.

In ridges in Tennessee west of Clinch Mountain, the Silurian clastic rocks were 

examined at 13 localities in three belts of outcrop. The Poor Valley Ridge (sandstone) 

Member, the mountain-forming member of the Clinch, thins by loss of sandstone units in 

a southwestward direction along the Big Ridge belt. Near the crossing of Lone Mountain 

by U.S. Interstate 75, the underlying Hagan Shale Member and the overlying Rose Hill 

Formation come together. From here southwestward, the combined sequence 

constitutes the Rockwood Formation. Northeast of 1-75, however, the Clinch Sandstone, 

including both its members, and the overlying Rose Hill Formation are identifiable and 

can be mapped separately. In the Poor Valley Ridge outcrop belt farther west, the Clinch 

Sandstone and the Rose Hill Formation are identifiable in Tennessee as in Virginia; in 

the Dutch Valley belt to the south and the Elk Valley belt to the west, no Poor Valley 

Ridge Member is present, and the name Rockwood Formation is applicable.

HI
H2 CONTRIBUTIONS TO STRATIGRAPHY

INTRODUCTION

Silurian formations of southwest Virginia and northeast Tennessee 

crop out in long northeast-trending belts which are separated from 

each other by major overthrust faults. Most of the belts terminate 

laterally against overthrust faults. In much of this region, the entire 

Silurian sequence consists of clastic sediments of Early and Middle 

Silurian age, some of which are resistant sandstones that form ridges 

or imposing mountains. Elsewhere, however, a carbonate formation of 

Late Silurian age intervenes between the clastic beds and the 

overlying Devonian formations.

In southwest Virginia, the Silurian formations are the Clinch 

Sandstone, the Clinton Formation, and the Hancock Limestone (or 

Dolomite). In Tennessee, the Clinch Sandstone and the Clinton 

Formation are recognized in some mountain belts; elsewhere Silurian 

clastic rocks have been called the Rockwood Formation, and the 

overlying carbonate rocks (if present) are the Hancock Limestone. In 

southwestermost Virginia and northernmost Tennessee, the Clinch is 

divided into a lower Hagan Shale Member and an upper Poor Valley 

Ridge Member. The name Rose Hill Formation is here introduced for 

rocks previously called Clinton Formation.

This study was undertaken (1) to determine the lithology and 

thickness of the Clinch Sandstone in its type area in Clinch Mountain 

and to establish a reference section for the formation somewhere along 

Clinch Mountain; (2) to determine the areal extent over which the two 

members of the Clinch can be recognized and mapped; (3) to examine 

the suitability of the name Clinton Formation in this region; (4) to 

determine the relations between the Clinch Sandstone, or the Clinch 

Sandstone and Clinton Formation combined, of Virginia and the 

Rockwood Formation of Tennessee.

Fieldwork contributing to the present investigation has been carried 

on by the author for many years in southwest Virginia and northeast 

Tennessee. Specific localities discussed in this report in Virginia and 

Tennessee were visited or revisited in June 1973. The author has also 

drawn on published reports, principally modern geologic quadrangle 

maps, for material in areas not visited.

ACKNOWLEDGMENTS

I am indebted to Robert Milici of the Tennessee Division of Geology 

and Helmuth Wedow, Jr., of the U.S. Geological Survey, not only for 

providing valuable information on the Rockwood Formation during 2 

days in the field, but also for allowing access to their unpublished 

material on the Upper Ordovician and Silurian stratigraphy in 

Sequatchie Valley and parts of the adjacent Valley and Ridge,
SILURIAN NOMENCLATURE AND CORRELATIONS, VA.-TENN. H3

Tennessee. They have been concerned with Silurian rocks in 

east-central and southeast Tennessee, whereas this paper is devoted to 

northeast Tennessee and adjacent Virginia.

REGIONAL SETTING

Silurian rocks crop out linearly in the Valley and Ridge province 

from southeastern New York to Alabama. Most of the Silurian System 

is represented by clastic rocks, of which the oldest formations 

(Shawangunk Conglomerate (or Formation) in New York, New Jersey, 

and eastern Pennsylvania; Tuscarora Sandstone in central Pennsylvania, Maryland, and northern Virginia; and Clinch Sandstone in 

southern Virginia and Tennessee) commonly form the highest and 

most prominent ridges in the province. Overlying these formations in 

many belts of outcrop is a sequence of beds, predominantly marine 

shale, which in western Maryland has been named the Rose Hill 

Formation (of the Clinton Group), by some authors but which in 

Virginia and Tennessee has in most reports been called the Clinton 

Formation. A carbonate formation of Late Silurian age, the Hancock 

Limestone (Sneedville Limestone of some authors), is present in some 

places in southwest Virginia and Tennessee overlying the clastic rocks 

but is absent elsewhere.

The linear belts of outcrop in southwest Virginia and northeast 

Tennessee are shown in figure 1. They are separated from each other 

by major overthrust faults dipping southeast, along which forward 

movement is measurable in miles. The outcrop belts strike northeast, 

which was also the approximate trend of the shorelines in Silurian 

time. Hence, the lithofacies are quite similar for many miles along the 

individual belts but differ materially from one belt to the next across 

the strike. This has been the principal factor in the problems of 

nomenclature and correlation with which this report is concerned.

ORIGIN AND USAGE OF FORMATION NAMES 

CLINCH SANDSTONE

Safford (1856) named the Clinch Sandstone to include the white 

relatively thick bedded sandstone and conglomerate, several hundred 

feet thick, that caps Clinch Mountain and other ridges in east 

Tennessee. Geographically, the name Clinch Mountain is applied to a 

continuous ridge extending from Burkes Garden near Tazewell in 

Tazewell County, Va., for 140 miles (225 km) southwest to an abrupt 

termination in Union and Grainger Counties, Tenn., where the belt of 

Clinch at the surface is cut off by the Saltville fault. Safford (1869) 

later further described the Clinch Sandstone but provisionally 

included in the formation the underlying red calcareous shale which
ffi

70 80 KILOMETRES

FIGURE 1. Map of southwest Virginia and northeast Tennessee showing belts of outcrop of Silurian formations, localities mentioned in text 

numbered 1 to 21, location of the lines of restored sections A-A' (fig. 2) and 5-5' (fig. 3), and areas in which Clinch Sandstone, Clinch Sandstone and Rose Hill Formation, and Rockwood Formation were deposited. The same locality numbers are used in tables 1 and 2.
SILURIAN NOMENCLATURE AND CORRELATIONS, VA.-TENN. H5

has subsequently been designated as the Juniata or Sequatchie 

Formation and dated as Late Ordovician. He did not designate a type 

section for the Clinch Sandstone, a common omission of those times. 

Later work, principally in U.S. Geological Survey folios, restricted the 

name Clinch to Safford's white sandstone unit, excluding the 

underlying red beds of Late Ordovician age. This work also extended 

the type area to include Clinch Mountain in Scott County, Va.

Miller and Fuller (1947, 1954), Miller and Brosge (1950, 1954), 

Miller (1965), and Miller and Roen (1971,1973) identified and mapped 

members of the Clinch Sandstone in the belts of outcrop northwest of 

Clinch Mountain in Lee and Wise Counties, Va. These are designated 

in figure 1 as the Powell Mountain belt, the Wallen Ridge belt, and the 

Poor Valley Ridge belt. The members are the Hagan Shale Member 

below and the Poor Valley Ridge (sandstone) Member above. Others 

have mapped these divisions of the Clinch in the Powell Mountain and 

Wallen Ridge belts to the southwest in Tennessee (Harris and others, 

1962; Harris, 1965; Harris and Mixon, 1970). Others (Englund and 

others, 1961, 1963; Englund, 1964) have recognized the two lithologic 

divisions of the Clinch in the Poor Valley Ridge belt but have not used 

the formal member names or mapped them separately. Recent 

mapping that has included the Clinch Mountain belt has used the 

name Clinch Sandstone for the mountain-forming sandstones except 

in reports on the Bristol and Wallace quadrangles (Bartlett and Webb, 

1971) and the Clinchport quadrangle (Brent, 1963), all in Virginia, 

where the name Tuscarora Sandstone from the central Appalachians 

was used.

CLINTON FORMATION-ROSE HILL FORMATION

The Clinton Group was named by T. A. Conrad in 1842 for exposures 

near Clinton in central New York. The name has had a long and varied 

history, but in the central Appalachians both historically and in recent 

years it has been maintained in group status. In the southern 

Appalachians, however, especially in southwestern Virginia and 

northern Tennessee, it has been considered a formation of Middle 

Silurian age between the Clinch Sandstone below and the Hancock 

(Sneedville of some authors) Limestone above. It has also been thought 

to be the formation that contains the "Clinton type" sedimentary 

hematitic iron ores. Miller and Fuller (1954), however, have shown 

that the Clinch Sandstone also locally includes "Clinton type" 

iron-rich beds, and R. C. Milici and Helmuth Wedow, Jr. (unpub. data, 

1974), have also found "Clinton type" iron-rich beds both in the Early 

Silurian part of the Rockwood Formation in central Tennessee and in 

the Shellmound (equivalent to Sequatchie) Formation of Late 

Ordovician age in southern Tennessee. Although the name Clinton 

Formation has been used by many workers in southwest Virginia and
H6 CONTRIBUTIONS TO STRATIGRAPHY

east Tennessee, including Butts (1940), Miller and Fuller (1954), 

Miller and Brosge (1954), Harris (1965), and others, it seems an 

ill-advised choice for these rocks, partly because of their remoteness 

from the type region in New York State and partly because of a history 

of disagreements as to what units should be included in the Clinton 

Group of the central Appalachians. Different usages are documented 

in the Lexicon of Geologic Names of the United States (Wilmarth, 

1938; Keroher, 1966).

Meanwhile, an excellent alternative to the use of the name Clinton 

in the southern Appalachians has existed since 1923. This is the Rose 

Hill Formation of western Maryland which has its type region almost 

midway between Clinton, N. Y. and southwest Virginia. The formation 

was named and meticulously described by Swartz (1923) and Prouty 

and Swartz (1923). The formation is still excellently exposed in 

railroad and highway cuts at Rose Hill on the west edge of 

Cumberland, Allegany County, Md. In western Maryland, the 

sequence of shale, thin-bedded sandstone, and hematitic "iron ore" 

beds is lithologically very similar to the Clinton Formation of 

southwest Virginia, and Miller and Fuller (1954) have shown that the 

ostracode zones (as identified by F. M. Swartz, written commun., 

1945) of the lower and upper part of the Clinton are the same as those of 

the Rose Hill. The name Rose Hill Formation was adopted for use in 

West Virginia by Woodward (1941), and it appears as one of the 

formations of the Clinton Group on the State Geologic Map of West 

Virginia (Caldwell and others, 1968). Cooper (1944) used the name 

Rose Hill in his report on the Burkes Garden quadrangle in Tazewell 

and adjacent counties of southwest Virginia and also in a field-trip 

guidebook (1961), but other workers did not follow his lead.

In westernmost Maryland and adjacent West Virginia, another 

name, Cacapon Sandstone, was applied by Barton and Taff (1896) to a 

red flaggy sandstone approximately equivalent to the lower part of the 

Rose Hill Formation. In the middle part of the Appalachian Valley of 

Virginia, Butts (1940) used Cacapon as the lower "division" of his 

Clinton Formation; the Cacapon is composed of shale and sandstone 

including "highly ferruginous sandstone of distinctive character." On 

the other hand, Lesure (1957) used the name Rose Hill Formation in 

the Clifton Forge region of west-central Virginia for beds that are 

lithologically similar to the type Rose Hill but that contain a large 

proportion of the distinctive red or reddish-purple ferruginous 

sandstone described by Butts. More recently, quadrangle mappers 

(Bick, 1962; Kozak, 1965, 1970; Rader, 1967, 1969; Spencer, 1968; 

McGuire, 1970) in and near the region of Lesure's work have applied 

the old name Cacapon Sandstone of Barton and Taff to these same 

beds. The lithology of the Middle Silurian beds of southwest Virginia,
SILURIAN NOMENCLATURE AND CORRELATIONS, VA.-TENN. H7

however, more closely resembles the Rose Hill Formation of western 

Maryland and eastern West Virginia than it does the ferruginous 

sandstone fades to which the name Cacapon has been applied. The 

Virginia Geological Survey is now dropping the name Cacapon in favor 

of Rose Hill Formation (Young and Rader, 1974). For all of the above 

reasons, therefore, it is recommended that the name Clinton 

Formation that has frequently been used in southwest Virginia and 

northeast Tennessee be superseded by the name Rose Hill Formation.

ROCKWOOD FORMATION

One purpose of the present investigation was to determine the 

relations between the Clinch and so-called Clinton (or Rose Hill) 

Formations of southwest Virginia and the Rockwood Formation of east 

Tennessee. In general, the practice in east Tennessee has been to map 

the Clinch Sandstone where it is thick and forms prominent mountain 

ranges but to apply the name Rockwood where the Silurian clastic 

rocks are dominantly shale and siltstone and where any ridges held up 

by these rocks are relatively low compared with the mountains to the 

east (Clinch Mountain, Powell Mountain, and Wallen Ridge).

The Rockwood Formation was named by Hayes (1891, p. 143) from 

the town of Rockwood, Roane County, Tenn. The name appeared in a 

graphic column without any description of the formation. In the 

Kingston (Tenn.) Folio, however, Hayes (1894) described the 

Rockwood Formation and included in it not only the Silurian clastic 

rocks but also the red calcareous mudstone, now named the Sequatchie 

Formation and dated as Late Ordovician. The name Rockwood has 

since been restricted to the overlying Silurian beds, which are 

lithologically quite distinctive and are easily separable from the 

Sequatchie beds (E.G. Ulrich, in Burchard, 1913, p. 31; Rodgers, 1953, 

p. 100).

The equivalence of the Rockwood to other named Silurian clastic 

formations in the bistate area has been unclear. The Rockwood has 

been considered (1) the fine-grained western equivalent of the Clinch 

Sandstone and of Early Silurian (Brassfield) age (Ulrich, in Burchard, 

1913, p. 31; Berry and Boucot, 1970); (2) the equivalent of the Clinch 

and Clinton (Rose Hill) Formations of northernmost Tennessee west of 

Clinch Mountain, and of southwest Virginia, thus of Early and Middle 

Silurian age (Swingle, 1960a, b; Englund, 1964); and (3) the Tennessee 

equivalent of the Clinton (Rose Hill) of southwest Virginia and hence 

of Middle Silurian age (Englund, 1968; Swingle and others, 1966).

CLINCH SANDSTONE

CLINCH MOUNTAIN BELT AND REFERENCE SECTION

The type area of the Clinch Sandstone, as previously indicated, is
H8 CONTRIBUTIONS TO STRATIGRAPHY

Clinch Mountain in northeast Tennessee and southwest Virginia. The 

formation dips consistently southeast with dips from 15° to nearly 

vertical. The lowermost beds crop out a few tens of feet northwest of the 

crest of the mountain; the rest of the formation occupies the upper and 

middle slopes of the southeast flank. In places, dip slopes have formed 

for hundreds of feet, but in general the beds dip somewhat more steeply 

than the mountain slope. Because of the abundant cover of colluvium, 

the long difficult traverses required in trying to measure sections of the 

Clinch along sidehill roads or trails, and the unsatisfactory number of 

outcrops down the mountain side, it is understandable that only one 

section of the Clinch on Clinch Mountain has been published in all the 

years since Safford named the formation. Even the thickness of the 

formation is difficult to determine, and published thicknesses have 

been highly generalized, for example, "200 feet," "300 feet," 

"maximum approximately 500 feet." Their order of magnitude is 

somewhat suspect.

The writer has examined every potential section along the roads 

that overtop the mountain from Russell County, Va., to Knox County, 

Tenn., and also potential sections in the two water gaps that cut the 

mountain, both in Virginia. A summary of each of these is shown in 

table 1, the numbers keyed to the numbering system on figure 1.

The best section of the Clinch, in the writer's opinion, is in the 

water gap where Little Moccasin Creek and U.S. Highways 19 and 

Alternate 58 penetrate Clinch Mountain 8 miles (13 km) north of 

Abingdon, Va. (fig. 1, No. 2). This is named Moccasin Gap on the 

Brumley (1:24,000) topographic quadrangle map but is here referred to 

as Little Moccasin Gap to avoid confusion with the water gap at Gate 

City (fig. 1, No. 3) where Big Moccasin Creek cuts through the 

mountain, and which is also named Moccasin Gap on the Gate City 

(1:24,000) topographic map.

Butts (1940, p. 231) measured and published a stratigraphic section 

through Little Moccasin Gap, assigning 125 feet (38 m) of even-bedded 

white sandstone in one undivided unit to the Clinch Sandstone and 361 

feet (110 m) of overlying beds, predominantly sandstone, to the 

overlying Clinton Formation. Since Butts' work, a new superhighway 

has been constructed through the gap with longer roadcuts, creating 

excellent exposures of most of the Clinch and the lower part of the 

overlying Rose Hill (Clinton) Formation. The author intended to 

designate this as the type section of the Clinch Sandstone. Dennison 

(Dennison and Boucot, 1974), however, has published a detailed 

section of the Clinch at Little War Gap, Kyles Ford quadrangle, 

Tennessee (fig. 1, No. 4), and has designated this as the type section of 

the Clinch Sandstone. The section given below is therefore here 

designated as a reference section of the Clinch.
SILURIAN NOMENCLATURE AND CORRELATIONS, VA.-TENN. H9

Section of Clinch Sandstone (reference section) and 

lower part of Rose Hill Formation

[Measured along U.S. 19 and 58 Alt. in Little Moccasin Gap through Clinch Mountain (Brumley quadrangle, 1:24,000) 

8 miles (13 km) north-northwest of Abingdon, Washington County, Va. All the section is on west side of divided 

four-lane highway. Section begins 100 feet (30 m) north of turn-around lane directly south of John Douglas Memorial 

Wayside and ends at area of deformed slumped beds near south end of cut. Dip of beds 25° SSE]

Thickness 

(feet) (metres*

Slumped beds, dipping anomalously, to south end of highway cut. 

Rose Hill Formation (in part):

26. Sandstone, light-gray, fine-grained, resistant; zone of shale 

in middle. Beds somewhat disturbed by slumping and by 

small fault above ______________________ 25 + 7.6+

25. Shale, medium-gray; some has a red cast. Fault, probably

small, at top of unit __________________________ 29 8.8

24. Siltstone, medium-dark-gray. Contains crinoid columnals.

Resistant unit _________________________ 1-3 0.3-0.9

23. Shale, medium-gray; contains a few pale-red beds and a few 

beds of siltstone 1-2 in. (2.5-5 cm) thick. Contains 

Eocoelia hemisphaerica (brachiopod),Mastigobolbina lata 

(ostracode), crinoid columnals, fucoids, and worm trails 18 5.5

22. Sandstone, very fine grained; coated with films of 

greenish-gray mudstone and contains patches of 

grayish-red sandstone in lower part ________________ 10 3.1

21. Sandstone, fine-grained; in beds as much as 3 ft (1 m) thick,

coated with films of mudstone. Moderately resistant __ 8 2.4

20. Sandstone, fine-grained; platy bedded in lower half, 

changing to medium-gray shale in upper half. Irregular 

bedding surfaces coated with mudstone 6 1.8

19. Shale, medium-gray, and sandstone, light-gray, very fine 

grained, with undulatory bedding. Each sandstone bed is 

sandwiched by shale layers. In lowest 2 ft (0.6 m), 

sandstone composes 60 percent of unit, but upper part of 

unit is almost entirely shale. Basal bed contains shale 

pellets as much as J/2 in. (1.3 cm) in size and other trash 9 2.7

Thickness of lower part of Rose Hill Formation ______ 107+ 32.5+

Clinch Sandstone:

18. Sandstone, light-gray, very fine grained; in beds 1-4 in.

(2.5-9 cm) thick. Transition zone_______________ 4 1.2

17. Sandstone, light-gray, very fine (grained; laminated, in one

massive resistant unit ____________________ 5 1.5

16. Siltstone, gray (faint grayish-red tint at top), nubbly _ 4 1.2 

15. Shale, gray, weathered____________________ 2 .6

14. Sandstone, gray, and siltstone containing a 1-ft-thick (0.3

m) grayish-red zone in middle_________________ 11 3.4

13. Siltstone, mottled grayish-red and medium-gray. Conspicuous where weathering has accentuated the colors. 

Some black manganese oxide staining. Similar beds have 

been found near the top of the Clinch Sandstone in other 

outcrop belts__________________________________ 6 1.8
H10 C DISTRIBUTIONS TO STRATIGRAPHY

Section of Clinch Sandstone (reference section) and 

lower part of Rose Hill Formation Continued

Thickness 

(feet) (metres)

12. Siltstone, greenish-gray, mottled, earthy; weathers yellowish and reddish brown. Thin bedded but poorly denned 

bedding in more massive units ________________ 17 5.2

11. Sandstone, fine-grained, moderately quartzose; contains a

few shale partings as much as 4 in. (10 cm) thick __ 19 5.8 

10. Sandstone, thin-bedded, and shale medium-gray, interbedded ___________________________________ 4 1.2

9. Sandstone, light-gray, fine-grained, moderately quartzose;

in beds 2 in. (5 cm) to 2 ft (0.6 m) thick _________ 26 7.9

8. Shale, medium-gray, and sandstone, thin-bedded, interbedded. Lowermost shale zone in Clinch ____________ 4 1.2

7. Sandstone, light- and medium-gray, moderately quartzose;

in beds 1 to 2 ft (0.3-0.6 m) thick ______________ 22 6.7

6. Sandstone, fine-grained, and a little siltstone in beds % in. 

to 2 ft (1-60 cm) thick. Thinner bedded and less quartzose 

than units 3 and 4. Arthrophycus near base ______ 42 12.8

5. Largely covered but a few beds exposed of fine-grained 

sandstone, thinner bedded and less quartzose than 

underlying units _____________________ 52 15.9

4. Sandstone, white, quartzose; medium grained in lower 

part, changing to fine grained upward. Some beds have 

shallow oval pits where clay or shale galls have 

weathered out _______________________ 55 16.8

3. Sandstone, white, medium-grained, quartzose; in massive

beds as much as 5 ft (1.5 m) thick ____________ 21 6.4

Total thickness of Clinch Sandstone___________ 294 89.6

Juniata Formation (in part):

2. Covered, but largely or entirely Juniata__________ 19 5.8 

1. Siltstone, grayish-red and greenish-gray; contains a little 

mudstone. Even bedded but weathers into irregularly 

shaped crumbly cobbles. Most beds are 1-6 in. (2.5-15 cm) 

thick ______________________________ 12+ 3.7+

Thickness of Juniata Formation (in part) ____ _ 31+ 9.4+

The large discrepancy between Butts' (1940) thickness of the Clinch 

and the thickness given in the above reference section is largely 

because Butts included in his Clinch Sandstone only the lowermost 

white massive-bedded sandstone, more or less equivalent to units 3, 4, 

and probably part of 5. The overlying beds, here included in the Clinch 

Sandstone, were assigned by him to the Clinton Formation (Rose Hill 

Formation of this report), probably in part because of the thinner 

bedding and the presence of some interbedded shale. In many other 

places, along Clinch Mountain and in the ranges to the west, the
SILURIAN NOMENCLATURE AND CORRELATIONS, VA.-TENN. Hll

author has seen thin units of shale in the middle and upper parts of the 

Clinch. The sandstone beds in this upper part of the Clinch Sandstone 

are indeed less quartzose than in the lower part of the formation, but 

they have clay galls, worm tubes, and other littoral-type features, and 

they lack marine fossils. Butts (1940, p. 231) remarked on the "lumpy 

mottled red and green rocks*** persistent in this region" which are 

probably units 12 and 13 of the above section. The writer has noted this 

lithology in the upper part of the Clinch Sandstone, not only elsewhere 

along Clinch Mountain where the Rose Hill was entirely lacking, but 

also in the Poor Valley Ridge Member of the Clinch in mountain 

ranges to the west. The evidence thus seems to justify placing in the 

Clinch some 170 feet (52 m) of beds that Butts included in his Clinton 

Formation.

Other sections along Clinch Mountain in Virginia and Tennessee 

are described briefly in table 1; at most of these places it would be 

extremely difficult to get a good measured section along the present 

roads or by traversing down the steep, timbered, and largely 

colluvium-veneered slopes.

It should be noted in table 1 that only at Big War Gap, Lee Valley 

quadrangle, Tennessee (fig. 1, No. 5), were any Rose Hill rocks found 

overlying the Clinch, as they do conspicuously at Little Moccasin Gap. 

At Big War Gap 2 feet (0.6 m) of Rose Hill was exposed. Elsewhere, a 

few feet (about 1 m) to perhaps 20 or more feet (6 m) of the Wildcat 

Valley Sandstone of Early Devonian age lies between the Clinch and 

the overlying thick Middle and Upper Devonian dark-gray shales 

(Chattanooga Shale and equivalent formations).

RIDGES WEST AND NORTH OF CLINCH MOUNTAIN

In the three Silurian belts west and north of Clinch Mountain in 

southwest Virginia and northernmost Tennessee, the basal unit of the 

Clinch Sandstone is not the resistant mountain-forming sandstone 

typical of Clinch Mountain, but rather a gray shale unit containing a 

few thin beds of platy fine-grained sandstone, and (or) silty to sandy 

limestone. At many localities there is a basal bed 1 to 3 feet (0.3-0.9 m) 

thick of resistant medium-grained sandstone. This sequence was 

named the Hagan Shale Member of the Clinch (Miller and Fuller, 

1954). The member ranges from 50 to 130 feet (15-40 m) in thickness.

The Hagan Shale Member is overlain by resistant beds of 

medium-grained sandstone similar to the mountain-forming 

sandstones of Clinch Mountain. These beds were designated the Poor 

Valley Ridge Member of the Clinch Sandstone by Miller and Fuller 

(1954). The Poor Valley Ridge Member is almost entirely fluvial in the 

Powell Mountain and Wallen Ridge belts, where it is about 180 feet (55 

m) thick. It is somewhat thinner and also contains many tongues of
TABLE 1. Clinch Sandstone along roads crossing Clinch Mo

Name of 

section

Hayters 

Gap.

No. Quadrangle 

in fig. 1 (1:24,000)

1 Hayters Gap, 

Va.

Number and quality 

of outcrops

Abundant and good in 

lower part of formaDescription

Coarse quartzose sand

at base, overlain by 

Little Moccasin 

Gap.

Big Moccasin 

Gap.

Brumley, Va.

Gate City, Va.

null uin_y. JT uui pidi_c

for measured section.

Abundant and excellent except in middle 

part of formation 

(reference section).

Major fault traverses 

gap. Silurian formations largely absent 

at creek, highway 

and railroad level.

um-grained sandsto

beds 2l/2 in. (10 cm) t

(0.6 m) thick. One z

hematitic sandstone 

2x/2 in. (10 cm) thick 

top.

Sandstone, white, me

grained in lower part; 

stone, gray, fine-gr

containing shale and 

stone beds in upper 

See measured sectio

details.

No section possible be

of faulting.
Little War

Gap.

Big War

Gap.

Flat Gap

Bean Gap ____

Powder Spring

Gap.

4 Kyles Ford,

Tenn.

5 Lee Valley,

Tenn.

6 Lee Valley,

Tenn.

7 Avondale,

Tenn.

8 Luttrell,

Tenn.

Lower and upper contacts well exposed.

Many discontinuous

outcrops in between.

Few outcrops. No section possible.

Excellent exposures of

lower part. Very few

outcrops of middle

and upper parts.

Base excellently exposed. Scattered exposures of overlying

lower part. A few

outcrops near top.

Few outcrops. No section possible. Lower

and upper contacts

and most of Clinch

covered.

White, quartzose, local

bly in lower part. 

part finer grained

quartzose; purplis

iron-stained beds ne

Lowermost beds of 

fine-grained qua

sandstone, becoming 

um grained upward

zones of red and gree

near base.

Basal Clinch fine-g

moderately quartzos

stone. Lower part fi

medium-grained san
H14 CONTRIBUTIONS TO STRATIGRAPHY

fossiliferous shale in the Poor Valley Ridge belt. As a result, Poor 

Valley Ridge is a lower and much less prominent ridge.

In all outcrop belts, the Clinch Sandstone lies disconformably on the 

Sequatchie Formation (Upper Ordovician), a red calcareous siltstone 

and mudstone, or on its red largely noncalcareous eastern equivalent, 

the Juniata Formation.

AGE

The Clinch is essentially unfossiliferous in Clinch Mountain, except 

for worm burrows such as Arthrophycus and Scolithus. In the belts to 

the west, however, the Hagan Shale Member is sparingly fossiliferous 

in most localities, as is the overlying Poor Valley Ridge Member. At 

Cumberland Gap, Tenn., in the Poor Valley Ridge belt, however, Butts 

(1940, p. 235-237) has described an abundant marine fauna from the 

Clinch. Butts' measured section at this locality (1940, p. 232) is 

incorrect because of an error in projecting from a highway cut for the 

lower part of the section to a railroad cut for the upper part (Miller and 

Fuller, 1954, p. 147-148, pi. 29), but the validity of his fossil evidence is 

unaffected. On the basis of this fauna, Butts correlated the Clinch with 

the Albion Sandstone of New York and the Brassfield Limestone of 

Ohio, both Early Silurian in age. In the three mountain belts west of 

Clinch Mountain, the lowermost beds of the overlying Rose Hill 

Formation contain abundant Eocoelia hemisphaerica (formerly 

Coelospira hemisphaerica). The ostracode Zygobolba anticostiensis has 

also been found in these lowermost beds of the Rose Hill. This ostracode 

is considered diagnostic of the earliest Niagaran Series in its type area 

in Maryland (Swartz, 1923, p. 30) and is early Middle Silurian in age. 

Hence, the Clinch of the western belts in southwest Virginia and 

northeast Tennessee is Early Silurian.

In the reference section of the Clinch at Little Moccasin Gap through 

Clinch Mountain, the lowermost fossiliferous beds of the overlying 

Rose Hill, 23 feet (7 m) above the base of the formation, contain 

Mastigobolbina lata. This ostracode is considered diagnostic of the 

middle part of the Rose Hill Formation and is of Middle Silurian age. 

The Clinch gives way upward to the overlying Rose Hill through a 

4-foot-thick (1.2-m) transition zone, no unconformity or disconformity 

being present. It is thus possible that the Clinch at this reference 

section is both Early Silurian and early Middle Silurian in age. 

Whether this is also possible elsewhere in the Clinch Mountain belt is 

unknown, but the presence of varicolored mottled purplish beds near 

the top of the formation in several Tennessee localities, matching 

similar beds in about the same position in Virginia, suggests 

continuity of these beds from one end of Clinch Mountain to the other.
SILURIAN NOMENCLATURE AND CORRELATIONS, VA.-TENN. H15 

ROSE HILL FORMATION

The Clinch is overlain in the Powell Mountain, Wallen Ridge, and 

Poor Valley Ridge belts by the Rose Hill Formation. The Rose Hill is 

predominantly shale but contains platy beds of fine-grained sandstone 

and hematitic beds from fractions of an inch to 2 feet (0.6 m) thick in its 

lower part. Locally it also contains a few thicker sandstone units which 

somewhat resemble some of the sandstone beds in the upper part of the 

Clinch but which are separated from the Clinch and from each other by 

much greater thicknesses of shale than are present in the Clinch.

The Rose Hill Formation is dated as Middle Silurian, predominantly 

by its ostracode faunas. In Lee County, Va., a distinct sedimentary 

break exists between the Clinch and the overlying Rose Hill; an abrupt 

lithologic change takes place at the contact, and abundant fossils are 

present in the lowermost Rose Hill beds, including particularly the 

small brachiopod Eocoelia hemisphaerica. Elsewhere, however, the 

exact contact between the Clinch Sandstone and Rose Hill Formation 

is difficult to select because shale partings and beds are present in the 

uppermost part of the Clinch, and fairly thick bedded sandstone units 

that resemble the quartzose fine-grained Clinch are locally present in 

the lowermost part of the Rose Hill Formation.

The Rose Hill Formation is about 325 feet (100 m) to 400 feet (120 m) 

thick in the Powell Mountain, Wallen Ridge, and Poor Valley Ridge 

belts. Measured sections under the name Clinton Shale have been 

published by Miller and Fuller (1954, p. 188) and Miller and Brosge 

(1954, p. 124-125). In the Clinch Mountain belt, the Rose Hill is absent 

at most localities; at Little Moccasin Gap, it is more than 88 feet (27 m) 

thick, and at Big War Gap, 2 feet (0.6 m) of exposed beds seem to belong 

to this formation. This suggests that the formation was probably 

deposited in the Clinch Mountain region but that at most localities it 

was removed by erosion in the diastem that encompassed all of Late 

Silurian time and Early Devonian time.

In the restored section (fig. 2) along the line A-A' (fig. 1), the 

intertonguing relation of the Clinch Sandstone in Clinch Mountain to 

the Clinch and Rose Hill Formations to the northwest is shown.

ROCKWOOD FORMATION

As previously noted, the Clinch Sandstone, containing two 

members, and the Rose Hill Formation are present in the Powell 

Mountain and Wallen Ridge belts in southwest Virginia and 

northernmost Tennessee. Father south and west, however, the 

resistant ridge-forming sandstone units of the Clinch Sandstone (Poor 

Valley Ridge Member) become thinner, and the name Rockwood 

Formation is in common use for the entire Silurian clastic sequence.
H16 CONTRIBUTIONS TO STRATIGRAPHY

A'

FEET METRES 

r- 200

20 25 KILOMETRES

FIGURE 2. Restored section along the line A-A' (fig. 1) showing the changes in facies 

and nomenclature from Clinch Mountain northwestward to Poor Valley Ridge.

The author has visited 11 localities in the Big Ridge, Dutch Valley, and 

Poor Valley Ridge belts of outcrop that seemed most favorable for good 

exposures of the Rockwood Formation. These localities are shown in 

figure 1, number 11-21, and the rock sections are summarized in table 

2. In the northern and eastern localities, both members of the Clinch 

Sandstone are recognizable and mappable, as is the overlying Rose 

Hill Formation. To the southwest, however, the Poor Valley Ridge 

(sandstone) Member pinches out, and the entire sequence is 

predominantly shale and thin platy-bedded sandstone to which the 

name Rockwood Formation is applied. These relations are described 

below by outcrop belt.

BIG RIDGE BELT

In the Big Ridge belt, the name Rockwood Formation has been used 

for the Silurian clastic rocks. In the northern part of the belt, however, 

(fig. 1) the sequence of rock units is the same as in Wallen Ridge, which 

is northeastward in the same fault belt. A well-developed Hagan Shale 

Member of the Clinch, a thinned but still resistant Poor Valley Ridge 

Member of the Clinch, and an overlying Rose Hill Formation are 

recognizable and mappable at Big Ridge (fig. 1, No. 11) and 

Andersonville Dock (fig. 1, No. 12). At Andersonville Dock, the Hagan 

Shale Member is more than 50 feet (15m) thick, the Poor Valley Ridge 

Member, about 25 feet (8 m) thick, and the Rose Hill Formation, 

apparently several hundred feet (100 m) thick but faulted. At Big 

Ridge, the Hagan Shale Member is at least as thick as at Andersonville 

Dock. The Poor Valley Ridge Member appears thicker, but poor 

exposures make it impossible to establish how much thicker. Here, 

also, fossiliferous Rose Hill beds overlie the Clinch along the shore of
TABLE 2. Silurian clastic formations at selected localities in southwest 

Name of No. m 

section fig. 1

JNo specinc y

sections. and

10

Big Ridge __ 11

Andersonville 12

Dock.

Name of Quadrangle 

outcrop belt (1:24,000)

Powell Coleman Gap,

Mountain Tenn.-Va.

and Wallen Howard QuarRidge. ter, Tenn.

Tazewell,

Tenn.

Big Ridge __ Maynardville,

Tenn.

Big Ridge Big Ridge Park,

Tenn.

Silurian clastic Number and 

formation present Quality of 

and exposed outcrops

Rose Hill Formation Fair

(Clinton Formation)

and Clinch Formation (Poor Valley

Ridge Member and

Hagan Shale Member).

Rose Hill Formation Fair to

and Clinch Sand- poor.

stone (Poor Valley

Ridge Member and

Hagan Shale Member).

Rose Hill Formation Fair

and Clinch Sandstone (Poor Valley

Ridge Member and

Hagan Shale Member).

R

T

S
TABLE 2. Silurian clastic formations at selected localities in southwest Virgini

Name of 

section

No. in 

fig. 1

Name of 

outcrop belt

Quadrangle 

(1:24,000)

Silurian clastic 

formation present 

and exposed

Number and 

Quality of 

outcrops 

Indian Gap 13 Big Ridge __ Norris, Tenn. __ Rose Hill Formation Fair ______ Se

Church. and Clinch Sand- 

stone (Poor Valley 

Ridge Member and 

Hagan Shale Mem- 

ber). 

U.S. Hwy. 14 Big Ridge ____ Norris, Tenn. __ None __________ Very poor __ Co

441 

U.S. Hwy. 15 Big Ridge ____ Norris, Tenn. __ Rockwood Formation Excellent..__ Ap

1-75 

Pilot Knob __ 16 Big Ridge __Clinton, Rockwood Formation Good _______ M

Tenn. 
Little 

Tunnel.

17 Poor Valley 

Ridge.

Middlesboro 

South, Tenn., 

Va., Ky.

Carr 

Chapel.

18 Poor Valley Ausmus, 

Ridge. Tenn.

LaFollette__ 19 Poor Valley Jacksboro, 

Ridge Tenn.

Dutch 

Valley.

20 Dutch

Valley.

Lake City, 

Tenn.

Emory Gap__ 21 Rockwood __Harriman,

Tenn.

Rose Hill Formation 

and Clinch Sandstone (Poor Valley 

Ridge Member and 

Hagan Shale Member).

Good

Rose Hill Formation Poor

and Clinch Sand- (mostly float), 

stone (Poor Valley Ridge Member and Hagan Shale Member).

Rose Hill Formation Poor

and Clinch Sand- (mostly float), stone (Poor Valley 

Ridge Member and 

Hagan Shale Member).

Rockwood Formation Very poor ____ Rockwood Formation Good.

New roadcut on U.S. 25 E through 

Poor Valley Ridge and old cut 

along L. & N. Railroad at north portal of "Little Tunnel" through Poor Valley Ridge. A few outcrops of Rose Hill Formation at 

NW. end of railroad cut. Resistant sandstone, exposed in railroad cut and at top of highway cut, apparently not more than 

15 ft (4.6 m) thick (Poor Valley 

Ridge Member of Clinch). Shale 

exposed in highway cut about 60 ft (18 m) thick (Hagan Shale 

Member of Clinch).

Traverse up and along spur 0.4 mile 

(0.7 km) northwest of Meyer Cemetery. Few exposures, but Hagan 

Shale Member of Clinch on southeast upper slope of southeast knob. Poor Valley Ridge Member 

of Clinch at crest, and Rose Hill 

Formation in saddle and on northwest knob are recognizable and 

mappable.

Traverse along elongate spur directly southwest of Roger Cemetery. Sandstone beds of Poor Valley Ridge Member of Clinch hold 

up 1430-ft (436-m) knob. Thin 

Hagan Shale Member of Clinch 

could be present southeast of crest. Float of Rose Hill Formation northwest of crest and in 

saddle.

A few exposures of shale of Rockwood Formation in this relatively flat valley. Rome Formation 

(Cambrian) thrust over Rockwood along southeast side of valley.

Reference section for Rockwood 

Formation measured and described by R. C. Milici. Predominantly gray shale; contains thin 

interbeddea sandstone units, and hematitic iron beds as much as 4.2 ft (1.3 m) thick. Transition zone 24 ft (7.4 m) thick into overlying Chattanooga Shale.

Miller and Fuller 

(1954); Butts (1940 p. 232).

R. C. Milici and 

Helmuth Wedow, 

Jr. (unpub. data, 

1974).

a o o ft)

C£5
H20 CONTRIBUTIONS TO STRATIGRAPHY

Norris Reservoir, but most of the outcrops of the formation are beneath 

the water except at times of low lake level. Southwest along the Big 

Ridge belt, fair exposures at Indian Gap Church (fig. 1, No. 13) also 

show both members of the Clinch as well as the Rose Hill Formation, 

the ridge-forming beds of the Poor Valley Ridge Member of the Clinch 

being 20 to 40 feet (6 to 12 m) thick.

Still farther southwest in the Big Ridge belt, excellent exposures 

along U.S. Interstate Highway 75 (fig. 1, No. 15) reveal beds 

approximately 70 feet (20 m) thick, consisting predominantly of shales 

that are the equivalent of the Hagan Shale Member to the northeast. 

One sandstone unit 6 feet (2 m) thick is present that could represent 

the wedge edge of the Poor Valley Ridge Member. At Pilot Knob (fig. 1, 

No. 16) there is no sandstone of the Poor Valley Ridge Member; thus 

beds equivalent to the Hagan Shale Member give way upward to beds 

equivalent to the Rose Hill Formation, and no criterion exists for 

separating the two. This sequence has been designated the Rockwood 

Formation (R. C. Milici, oral commun., 1973); it matches very well the 

sequence at the type locality (fig. 1, No. 21) of the Rockwood (R. C. 

Milici and Helmuth Wedow, Jr., unpub. data).

Figure 3 is a restored section along the line B-B'(fig. 1) near the 

Wallen Ridge and Big Ridge belts. It shows the tonguing out of the Poor 

Valley Ridge Member of the Clinch Sandstone, as described above, and 

the merging of the underlying Hagan Shale Member and overlying 

Rose Hill Formation into the Rockwood Formation close to the position 

of Highway 1-75. Thus, it seems appropriate in the Big Ridge belt to 

map Clinch Sandstone, with its two members, and Rose Hill Formation

B

Br

Indian AnderGap sonville 

Church Dock Big Ridge

(13) (12) (11)

Waller Ridge FEET METRES 

HO) ,- 200

FIGURE 3. Restored section along the line B-B' (fig. 1) showing the tonguing out 

southwestward of the Poor Valley Ridge Member of the Clinch Sandstone and the 

resultant changes in nomenclature. The numbers beneath the localities at the top of 

the section correspond to the locality numbers in figure 1.
SILURIAN NOMENCLATURE AND CORRELATIONS, VA.^TENN. H21

north of U.S. Highway 1-75 and to restrict the usage of the name 

Rockwood Formation to the area from 1-75 southwestward.

DUTCH VALLEY BELT

Dutch Valley is a narrow flat-floored intermontane valley just 

southeast of the Cumberland Plateau front (fig. 1, No. 20). Cambrian 

rocks are thrust northwestward on Silurian clastic rocks along the 

southeast wall of the valley. When this valley was traversed, a very 

few exposures of shale of Silurian age were found in several places. As 

no resistant sandstone beds seem to be present, such as those that form 

the Poor Valley Ridge Member of the Clinch, these beds are properly 

referable to the Rockwood Formation. In a report on the Lake City 

quadrangle, which includes the Dutch Valley area, Swingle (1960a) 

dated the Rockwood Formation as being of Early and Middle Silurian 

age. The author agrees with this age, on the basis of the lateral 

equivalency of the Rockwood to the Lower Silurian Clinch and Middle 

Silurian Rose Hill.

POOR VALLEY RIDGE BELT

In southwest Virginia, Poor Valley Ridge is a low ridge held up by 

the Poor Valley Ridge Member of the Clinch Sandstone. The Hagan 

Shale Member crops out on the uppermost slopes just southeast of the 

ridge crest, and the Rose Hill Formation is on the low northwest slopes 

and beneath adjacent Poor Valley.

Poor Valley Ridge extends southwestward into Tennessee as a 

separate and distinct ridge for 12 miles (19 km). Beyond this, however, 

a series of roughly alined knobs in many places reveal the presence of a 

more resistant unit, although in other places these rocks are 

overwhelmed and buried by debris from the high steep Cumberland 

Plateau escarpment close by on the west.

Traverses were made across the Poor Valley Ridge belt of Silurian 

clastic rocks at three localities. At Cumberland Gap, just south of the 

Tennessee-Virginia State line (fig. 1, No. 17, and table 2), the Hagan 

Shale and Poor Valley Ridge Members of the Clinch were described by 

Butts (1940) and Miller and Fuller (1954), as mentioned previously. A 

new highway cut on U.S. 25E now exposes the Hagan and basal beds of 

the Poor Valley Ridge perfectly, but the Rose Hill Formation has few 

exposures.

Southwest from Cumberland Gap, a traverse was made along a 

prominent pair of knobs near Carr Chapel in the Ausmus quadrangle 

(fig. 1, No. 18, and table 2). The Hagan Shale Member continues 

beneath the sandstone that holds up the eastern of the two knobs. The 

sandstone consists of hard fine-grained and very fine grained 

crossbedded sandstone in beds as much as 18 inches (46 cm) thick.
H22 CONTRIBUTIONS TO STRATIGRAPHY

These beds are referable to the Poor Valley Ridge Member of the 

Clinch. A few scattered outcrops and float of fossilferous beds overlying 

the Clinch are clearly the Rose Hill Formation.

A third traverse was made across the Poor Valley Ridge on the 

outskirts of La Follette (fig. 1, No. 19, and table 2). Here the presence of 

the Poor Valley Ridge Member of the Clinch, again holding up a knob, 

and shale of the overlying Rose Hill Formation was established by 

outcrops and float. The Hagan Shale Member is probably also present 

in its normal position but is covered. No resistant sandstone assignable 

to the Poor Valley Ridge Member was seen where 1-75 crosses the 

Silurian belt. Thus, the lower shale, equivalent to the Hagan, grades 

upward into the shale containing sandstone beds, and this sequence at 

the southwest tip of the Poor Valley Ridge belt is more appropriately 

named Rockwood Formation.

The evidence along the Poor Valley Ridge belt indicates that the 

Clinch Sandstone and the Rose Hill Formation are identifiable and 

mappable for almost the full length of the belt in Tennessee. 

Furthermore, the two members of the Clinch also are identifiable 

throughout the northeastern part of the belt in Tennessee, at least as 

far southwest as La Follette (fig. 1).

ELK VALLEY BELT

The northwesternmost belt of Silurian outcrop in Tennessee is in 

Elk Valley (fig. 1) where the Rockwood Formation is brought to the 

surface by the Pine Mountain overthrust for a distance of nearly 5 

miles (8 km) (Englund, 1968). Englund stated that the formation here 

consists largely of gray shale; it has very fine grained sandstone and 

siltstone at the base and thin beds of fine-grained sandstone and 

siltstone throughout. The pinchout of the Poor Valley Ridge Member of 

the Clinch takes place in the subsurface between the Poor Valley Ridge 

belt and the Elk Valley belt, probably closer to the former than the 

latter, as suggested by the dotted line in figure 1. A very small and 

rather enigmatic brachiopod collection from the basal beds of the 

Rockwood was provisionally assigned by Boucot (Englund, 1968, p. 8) 

to the Middle Silurian. This age designation, if substantiated by 

additional paleontologic evidence, would indicate that the Rockwood 

was laid down in a sea lapping westward onto the craton and that the 

Lower Silurian part of the Rockwood between the Poor Valley Ridge 

belt and the Elk Valley belt was never deposited.

REGIONAL APPLICATION OF SILURIAN FORMATION NAMES

The evidence has shown (1) that the Clinch Sandstone, locally 

overlain by the Rose Hill Formation, is essentially a lithologic unit in
SILURIAN NOMENCLATURE AND CORRELATIONS, VA.-TENN. H23

Clinch Mountain; (2) that to the northwest, in Lee and Wise Counties, 

Va., and Hancock and Claiborne Counties, Tenn., the Clinch is 

divisible into a lower shale member, the Hagan, and a resistant 

sandstone member, the Poor Valley Ridge, and that these are overlain 

by a much thicker predominantly shale formation, the Rose Hill; and 

(3) that in Tennessee the Poor Valley Ridge Member of the Clinch 

tongues out in a southwest direction, and the Hagan Shale Member of 

the Clinch and the overlying Rose Hill Formation come together to 

form the Rockwood Formation. The areas to which each relationship 

pertains have been shown in figure 1.

SUMMARY

1. The name Clinton, from New York State where it is a group, should 

not be used in Virginia and Tennessee. The name Rose Hill 

Formation, from Maryland, is preferable.

2. A reference section for the Clinch Sandstone has been established 

at Little Moccasin Gap, Washington County, Va.

3. In most of the Clinch Mountain belt, the Clinch is the only Silurian 

formation present, but at Little Moccasin Gap and Big War Gap, 

more than 88 feet (27 m) and 2 feet (0.6 m), respectively, of Rose Hill 

Formation overlie the Clinch.

4. Two members of the Clinch, the Hagan Shale Member and the Poor 

Valley Ridge Member, and an overlying clastic formation, the Rose 

Hill Formation, are identifiable in Lee County, Va., and in the 

Powell Mountain, Wallen Ridge, and Poor Valley Ridge belts, and in 

the northern part of the Big Ridge belt in Tennessee.

5. The Clinch in Clinch Mountain is of Early Silurian and perhaps 

early Middle Silurian age. West of Clinch Mountain, however, all 

the Clinch is of Early Silurian age.

6. Where the Poor Valley Ridge Member of the Clinch thins to 

extinction southwest of the above areas, the name Rockwood 

Formation is applicable to the entire section of clastic Silurian rocks.

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H24 CONTRIBUTIONS TO STRATIGRAPHY

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