Geologic units in Scott county, Virginia

Additional scientific data in this geographic area

Knox Group (Cambrian-Ordovician) at surface, covers 19 % of this area

Knox Group (Safford, 1869). Dolostone, limestone, and sandstone. Dolostone, light- to medium-gray, very-fine- to fine-grained, locally with pink streaks in the upper part; and very-light-gray to dark-gray and brownish-gray, medium- to coarse-grained, locally argillaceous dolostone near the base of the unit; greenish-gray shale partings locally present; chert is abundant in some parts of the unit. Limestone, blue gray to dark-blue-gray, very-fine- to coarse-grained, locally sandy. Sandstone, gray to brown, fine- to medium-grained. Limestone is dominant in the eastern thrust belts. The Knox Group ranges from 2000 feet in Southwest Virginia to 3560 feet in thickness to the east in Washington County (Bartlett and Webb, 1971). The Knox includes the Mascot, Kingsport, Chepultepec, and Copper Ridge Dolomites and the Maynardville Formation.

Rome Formation (Cambrian) at surface, covers 11 % of this area

Pumpkin Valley Shale and Rome Formation. Pumpkin Valley Shale (Bridge, 1945). Shale, light-greenish-gray to dark-greenish-gray, grayish-brown, and maroon; a few beds of similar colored siltstone; sparse beds of limestone and dolostone. The Pumpkin Valley Shale conformably overlies the Rome Formation. The formation is approximately 350 feet thick. Harris (1964) identified the Pumpkin Valley Shale of Southwest Virginia as a formation within the Conasauga Group; however, because of similar lithologies it is often indistinguishable from the Rome Formation and the two formations commonly are mapped together. Rome Formation (Hayes, 1891). Siltstone, shale, sandstone, dolostone, and limestone. Siltstone and shale, greenish-gray and grayish-red, laminated to thin-bedded. Sandstone, micaceous, locally glauconitic, greenish-gray and reddish-gray, very-fine- to medium-grained, thin-bedded. Dolostone, light- to dark-gray, aphanic to medium-grained, thin-to massive-bedded, with ripple marks and mudcracks. Lime stone, argillaceous, very-light-gray to dark-gray, thin- to medium- bedded. Carbonate rocks range from sparse 1- to 2- feet-thick beds in western Scott County to discontinuous units as much as 50 feet thick which comprise 30 to 40 percent of the formation in western Russell and Washington counties (Evans and Troensegaard, 1991; Bartlett and Webb, 1971). Maximum recorded thickness is 1500 feet in the Clinchport area (Brent, 1963); although this may have included the Pumpkin Valley Shale. A complete thickness has not been determined because the lowermost part of the Rome Formation is normally absent due to faulting.

Lee Formation (Pennsylvanian) at surface, covers 9 % of this area

Lee Formation (Campbell, 1893). Quartzarenite, conglomerate, sandstone, shale, siltstone, and coal. Quartzarenite, white, very-light- to light-gray, fine- to coarse-grained, locally conglomeratic, quartz-pebble conglomer te lenses, cross-bed ded, channel-fill deposits. Sandstone, feldspathic, micaceous, light-gray, fine- to medium-grained. Shale and siltstone, medium-dark-gray to dark-gray, interbedded; coal in several beds and zones. The quartzarenites terminate eastward by intertonguing and grading into finer grained and less quartzose rocks (Englund and DeLaney, 1966). Miller and Roen (1973) believe the lower three quartzarenites are Mississippian and intertongue with the Pennington Group. These die out northeastward from southwestern Lee County (Mill er, 1969). The quartzarenites in the upper part of the Lee tongue out or grade into fi ner clastic rocks of the Norton and Pocahontas Formations successively from highest to lowest southeastward (Englund, 1979; Miller, 1974). These quartzarenites consist of five tongues in northern Buchanan County (Lovett and others, 1992); but to the east only the lowest tongue exists (Whitlock, 1989; Nolde, 1989), and that grades eastward into sandstone in the New River Formation in eastern Buchanan, northeastern Russell, and western Tazewell counties. Formerly rocks east of the quartzarenites were considered Lee (Harnsberger, 1919; Virginia Division of Mineral Resources, 1963), but now are designated New River Formation (Englund, 1981) and correlative to the lower part of the Norton Formation. The Lee Formation thickens and truncates progressively older rocks northwestward (Miller, 1974). The intertonguing and unconformable relationship accounts for the great range in thickness for the Lee Formation. It ranges in thickness from 0 in southern Buchanan County (Meissner and Miller, 1981), to 1680 feet in Lee County (Miller and Roen, 1973).

Nolichucky and Honaker Formations (Cambrian) at surface, covers 9 % of this area

Nolichucky Formation. Refer to description under [nmrr]. Honaker Formation (Campbell, 1897). Dolostone, limestone, and shale. Dolostone, light- to dark-gray to dark-bluish-gray, aphanic to coarse-grained, thin- to massive-bedded, "butcher-block" weathering; with sparse interbeds of argillaceous limestone, and minor dark-gray chert. Limestone, argillaceous, ribbon-banded in part, light- to medium-gray, very-fine-grained, thick-bedded. Shale, greenish-gray, laminated to thin-bedded. The Honaker Formation is predominantly dolostone with subordinate limestone. The dolostone becomes more dominant in the northeastern part of outcrop belt (Evans and Troensegaard, 1991). Shale is locally present as a 20- to 60-feet-thick unit in the middle of the formation and as thin interbeds with the dolostone and limestone throughout the area. The Honaker Formation ranges from about 1000 to 1100 feet in thickness. It is laterally equivalent to the lower Elbrook to the east.

Moccasin or Bays Formation through Blackford Formation (Ordovician) at surface, covers 7 % of this area

Moccasin Formation, Bays Formation, Unit C, Unit B, and Unit A. Moccasin Formation (Campbell, 1894). Mudstone, shale, imestone, and sandstone. Mudstone and shale, dusky-red to dark-reddish-brown, calcareous, ripple-marks, and mud cracks common. Limestone, light-olive-gray, weathers very-light gray, aphanic with "birds-eyes", locally fossiliferous. The limestone generally is the middle member of the Moccasin southwest of Giles County. In eastern Giles County and northeastward a thin medium-grained, gray sandstone occurs near the base of the Moccasin. The thickness ranges from 0 in northern Alleghany County to about 600 feet in Scott County. Bays Formation (Keith, 1895). Siltstone, sandstone, mudstone, and limestone. Siltstone, grayish-red, olive- to light-olive-gray, locally calcareous, sandy in part. Sandstone, light-gray to yellowish-gray, fine- to very-coarse-grained, locally conglomeratic, calcareous. Mudstone, grayish-red, olive- to light-olive-gray, mudcracks common. Limestone, grayish-red to light-olive-gray, aphanic. Five distinct K-bentonites reported by Hergenroder (1966). Contacts are conformable except perhaps in Botetourt, Roanoke, and Montgomery counties. Thickness ranges from 105 feet north of Wytheville to 890 feet near Daleville in Botetourt County. From Scott and Washington counties to Highland County and northwest of the Pulaski and North Mountain faults, a multitude of stratigraphic names have been applied to the rocks between the Bays or Moccasin (above) and the Beekmantown or Knox (below). The lack of detailed geologic mapping, except in Scott and Giles counties, the restricted area of the two major stratigraphic studies (Cooper and Prouty, 1943; Kay, 1956), and the general disagreement as to mappability and correlation of units makes it impossible to apply specific stratigraphic nomenclature at this time. Therefore, the rocks are described as three packages of lithologies (from youngest to oldest): Unit C, Unit B, and Unit A. Unit C. Limestone, medium- to dark-gray, aphanic to fine-grained with thin, medium- to coarse-grained beds, argillaceous, nodular to planar-bedded, locally very fossiliferous. The following names have been applied to Unit C: Witten, Bowen, Wardell, Gratton, Benbolt, Chatham Hill, Wassum, Rich Valley, Athens, Ottesee, Liberty Hall, Fetzer, and Giesler. Unit B. Limestone, light- to dark-gray, aphanic to coarsegrained, black and gray chert nodules, carbonate mound buildups. This unit is characterized by grainstone with interbedded micrite and chert. The overlying Unit C is very argillaceous and lacks chert. The following names have been applied to Unit B: Wardell, Gratton, Benbolt, Lincolnshire, Big Valley, McGlone, McGraw, Five Oaks, Peery, Ward Cove, Rockdell, Rye Cove, Effna, Whitesburg, Holston, Pearisburg, and Tumbez. Unit A. Dolostone, light- to medium-gray, fine-grained, locally conglomeratic, cherty. Limestone, medium- to dark gray, fine-grained, locally cherty. Shale, light-gray to dusky red. A basal chert-dolomite conglomerate with clasts as much as cobble size is locally present on the unconformity surface. The following names have been applied to Unit A: Blackford, Elway, Tumbez, Lurich (lower part), and "basal clastics".

Nolichucky and Maryville Formations, Rogersville Shale, and Rutledge Formation (Cambrian) at surface, covers 7 % of this area

Nolichucky Formation (Campbell, 1894). Shale, siltstone, and limestone. Shale, locally calcareous, light-olive-gray and bluish-gray, fissile, with minor sandstone and dolomite. Siltstone, locally calcareous, yellowish-brown and grayish-orange, thin-bedded. Limestone, argillaceous to glauconitic, medium light-gray to dark-gray and bluish-gray, fine- to coarse-grained; contains oolitic- and flat-pebble conglomerate beds, locally stromatolitic. Shale and siltstone make up 20 to 50 percent of the formation (Derby, 1965). A limestone unit up to 165 feet in thickness is present approximately 100 feet above the base of the Nolichucky in northern Russell County (Miller and Meissner, 1977). The Nolichucky Shale ranges from 440 to 690 feet in thickness in Southwest Virginia but pinches out to the northeast in Giles County. Maryville Formation (Keith, 1895). Limestone, locally dolomitic, silty, medium- to dark-gray and bluish-gray, locally ribbon-banded, generally thick-bedded; with thin shale interbeds and sparse dolostone beds. May be as much as 60 percent oolitic limestone in some areas (Harris and Miller, 1958). The Maryville ranges from 500 to 700 feet in thickness. Rogersville Shale (Campbell, 1894). Shale, silty in part, dark-bluish-gray and dark-greenish-gray, fissile, with minor siltstone, limestone, dolostone, and sandstone. The Rogersville Shale ranges from 60 to 110 feet in thickness. Rutledge Formation (Campbell, 1894). Limestone and dolostone. Limestone, locally dolomitic, silty partings, medium-dark-gray to bluish-gray, thick-bedded, mottled, ribbon- banded, with minor chert. Dolostone, light-olive-gray and dark-gray, fine- to medium-grained, present in the upper part of the formation in eastern Scott County. The formation forms prominent bluffs on the south-side of Clinch River and Copper Creek in Scott and Russell counties. The Rutledge ranges from 215 to 375 feet in thickness. The Maryville Formation, Rogersville Shale, and Rutledge Formation grade from predominantly limestone with subordinate dolostone and shale in southeastern Lee County and southwestern Scott County to limestone with a middle dolostone and thin shale near the Scott County-Russell County line. Northeast of this area the laterally equivalent rocks are predominantly dolostone with subordinate lime stone at the top and bottom and are called the Honaker Formation (Evans and Troensegaard, 1991).

Mississippian Formations Undivided (Mississippian) at surface, covers 5 % of this area

Pennington Group, Bluefield Formation, Greenbrier Limestone, Maccrady Shale, and Price Formation; includes Newman Limestone, Fort Payne Chert, and Grainger Formation in western Lee County. Refer to individual units for descriptions.

Greenbrier Limestone (Mississippian) at surface, covers 4 % of this area

Greenbrier Limestone (Rogers, in Macfarlane, 1879). Limestone, dolomite, and minor shale. Limestone, very-light olive-to olive-gray and brownish-gray, and medium- to dark gray, micrograined to coarse-grained, thin- to thick- bedded, thinner bedded in upper part, even- to cross-bedded; few shaly beds in upper part; oolitic in upper part and in cross-laminated beds near base; black chert near middle of formation, gray to pale-red near base; very fossiliferous. Pale-brown dolomite near upper chert zone, minor dolomite locally in lower part. Few interbeds of greenish-gray and grayish-red, calcareous, silty shale. Limestone is petroliferous locally in upper part (Henika, 1988). Base locally unconformable with underlying Maccrady Shale. Formation thickens to east, ranging from 200 feet in western Wise County to 3500 feet in Washington nd Scott counties. The Greenbrier is equivalent to (descending): Gasper Limestone, Ste. Genevieve Limestone, St. Louis Limestone (Hillsdale Limestone), and Little Valley Limestone (Warsaw equivalent), and to lower part of the Newman Limestone (Butts, 1940; LeVan and Rader, 1983). Newman Limestone (Campbell, 1893). Limestone and shale. Limestone, light-olive-gray in lower half, medium-gray to olive-gray in upper half, aphanic to fine-grained, partly oolitic, partly argillaceous, with basal beds of dark-gray chert nodules and local dolomite. Shale, medium-gray to medium dark-gray, partly calcareous, interbedded with limestone in upper half of unit. The Newman Limestone ranges from 550 to 600 feet in thickness and is equivalent to the Bluefield Formation and Greenbrier Limestone. Fort Payne Chert. (Smith, in Squire, 1890). Greenish gray chert in thin beds (2 - 6 inches thick); with shale partings. The Fort Payne Chert ranges from 0 to 20 feet in thickness and pinches out to the northeast. Grainger Formation (Campbell, 1893). Shale, pale-olive or greenish-gray to dark-greenish-gray, locally gray ish-red in lower half and at top; with some interbedded pale-olive-gray siltstone and very-fine-grained sandstone, locally abundant siderite nodules near base. The Grainger Formation ranges from 250 to 325 feet in thickness and is the lateral equivalent of the Maccrady Shale and Price Formation.

Pennington Group (Mississippian) at surface, covers 4 % of this area

Pennington Group (Campbell, 1893). Bluestone Formation, Princeton Sandstone, and Hinton Formation. Raised to Group rank by Harris and Miller (1958). The group consists of shale, sandstone, mudstone, conglomerate, siltstone, minor limestone, and coal locally. The shale, siltstone, and mud stone are gray to black and shades of red, and mottled red and gray. The sandstone is locally quartzose and conglomeratic, and ranges from shades of gray to brown, and only locally mottled within red shales; many sandstones pinch out southwestward in the Tazewell County area, but two persist farther west and southwest. The limestone is gray to brown, generally near the middle of the group, and is the most widespread marine unit. The Bluestone and Hinton For ma tions thin to the westsouthwest in southwestern Virginia; the widespread sandstone and limestone members nearly converge southwestward to with in 80 feet of each other from about 600 feet of separation in northern Tazewell County. The Princeton Sandstone wedges out in Tazewell County. The top of the Pennington Group is intertonguing to unconform ble with the overlying Lee Formation in the western part of the Southwest Virginia coalfield; basal contact is conformable. The Group thins westward; variation in thickness partly due to intertonguing and the unconformity. The Pennington Group ranges from 235 feet in thickness without the Pinacle Overlook Member of the Lee (as interpreted from Vanover and others, 1989) in the south west to 2355 feet (Trent and Spencer, 1990) in Tazewell County and 1335 feet in a partial section in Washington County (Bartlett and Webb, 1971), where it is mapped as the Pennington Formation. Bluestone Formation (Campbell, 1896). Sand stone, siltstone, shale, mudstone, minor limestone, coal, and underclay. Sand stone, argillaceous, micaceous, locally quartzose, verylight to dark-gray, light-olive- to greenish-gray, yellowish-orange to dark-yellowish-brown, moderate-red, very-fine- to medium-grained, thin- to very-thick-bedded, cross-bedded, locally ripple-bedded, interbedded with shale and siltstone; forms ledges and cliffs. Sand stone in middle of formation in Scott and Russell counties is conglomeratic with quartzite pebbles and other rock clasts (Evans and Troensegarrd, 1991; Nolde and Diffenbach, 1988). Upper part intertongued with Lee in northern Lee County (Miller and Roen, 1973). Siltstone, shale, and mudstone, partly calcareous, greenish-gray, dark gray to grayish-black, pale- to moderate-red and mottled red and greenish-gray; siderite nodules in variegated shales and silt stones; fossils in dark-gray shale (Englund, 1968). Limestone, argillaceous, medium-gray, thin, lenticular, fossiliferous, in middle of formation, and in thin discontinuous beds at the base of the formation in the sub sur face in western Tazewell and eastern Buchanan Counties (Englund, 1981). Thin coal bed in upper part of formation in northern Lee County (Miller and Roen, 1973); coal and impure coal in thin discontinuous beds in middle of formation in northern Tazewell County; underlain by underclay, locally as much as three feet thick, with root casts (Englund, 1968). Top un con form able with the overlying Lee Formation in northwestern Wise and Dickenson counties and extreme northwestern Buchanan County but is intertonguing to the southeast (Mill er, 1974) and southwest in northern Lee County (Miller and Roen, 1973). Base conformable with the underlying Princeton Sandstone in northern Tazewell County, but is disconformable to the southwest because the Princeton wedges out southwestward in Tazewell County and the Bluestone lies on the Hinton Formation (Englund and Thomas, 1990). Bluestone thins northwestward and ranges in thickness from 40 feet in southwestern Lee County (Englund, Landis, and Smith, 1963) to as much as 850 feet to the northeast in Tazewell County (Englund and Thomas, 1990). Princeton Sandstone (Campbell and Mendenhall, 1896). Sandstone, light-gray to light-greenish-gray, weathered locally to pale-reddish-brown, fine- to coarse-grained, thin- to very thick- bedded, locally cross-bedded, calcite cemented, becomes friable upon weathering, contains conglomerate lenses as much as two feet thick with well-rounded to angular pebbles of quartz, shale, silt stone, limestone, chert, and ironstone; fossils in limestone clasts (Englund, 1968, 1979; Trent and Spencer, 1990). Wedges out southwestward in west-central Tazewell County (Englund, 1979). The Princeton as mapped in Lee County and southwestern Scott County (Harris and Miller, 1958; Miller and Roen, 1973) is a different sandstone. The Princeton ranges from 0 to 60 feet in thickness. Hinton Formation (Campbell and Mendenhall, 1896). Shale, siltstone, mudstone, sandstone, limestone, minor coal, underclay. Shale, siltstone, and mudstone, partly calcareous, grayish-red, medium-gray, and greenish-gray, fossiliferous. Sandstone, quartzose, feldspathic, very-light- to medium-light gray, greenish-gray, yellowish-brown, pale- to moderate-red, locally mottled, very-fine- to medium-grained, thin- to very thick- bedded, contains quartz-pebble con lomerate, tree trunk impressions, and coal fragments; cobbles in lowest member locally; interbedded with dark-gray to grayish-black shale. A widespread conglomeratic sandstone in the upper part of the formation has been misidentified as the stratigraphically higher Princeton Sandstone (Englund, 1979). Limestone, argillaceous, light-grayish-brown, medium-gray, thin-bedded, nodular, very fossiliferous, contains marine fossils of Chesterian age and is most widespread marine unit (Little Stone Gap Member) in the Hinton (Englund, 1979). Base conformable. The formation ranges from 164 feet in thickness in southwestern Lee County to 1320 feet in northern Tazewell County (Englund, 1968, 1979).

Chepultepec and Copper Ridge Formations (Cambrian-Ordovician) at surface, covers 3 % of this area

Chepultepec Formation (Ulrich, 1911). Dolostone, argillaceous, sandy, light-gray, light-olive-gray, and grayish-brown,very-fine- to coarse-grained. Contains white to light-gray chert nodules and beds; sandstone and dolomitic sand stone lenses and beds; scattered sand grains; minor intraformational conglomerate beds; greenish-gray clay shale partings; and dark-gray, petroliferous dolostone. The Chepultepec ranges from 300 to 850 feet in thick ness (Brent, 1963). Copper Ridge Formation (Ulrich, 1911). Dolostone, generally divisible into a lower olive-brownish-gray to darkgray, medium- to coarse-grained, thick- to massive-bedded dolostone, some of which emits a petroliferous odor on freshly broken surfaces ("stinkstone"); and an upper olive-brownish- gray to light-gray, very-fine- to medium-grained dolostone with minor silty and sandy zones. Olive-black, oolitic chert beds and light-gray to white, chalcedonic chert nodules are present. Similar divisions were described by several geologists including Miller and Brosgé (1954), Miller and Fuller (1954), and Bridge (1956). The Copper Ridge ranges from 415 to 850 feet in thickness. Maynardville Formation (Oder, 1934). Limestone and dolostone. Limestone, locally dolomitic, locally argillaceous, medium- to dark-gray, very-fine- to fine-grained, medium- to thick-bedded, mottled; with argillaceous to dolomitic bands and partings which give the rock a ribbon-banded or straticulate appearance. Dolostone, very-light-gray to dark-gray, light-olive-gray to olive-gray and locally yel low ish-gray or dark-bluish-gray, very-fine- to coarse-grained, finely laminated to thick-bedded (thin-bedded near top of unit distinguishes it from overlying Copper Ridge Formation); with black chert; minor lenses and beds of fi ne- to medium-grained, locally dolomitic sandstone; very-fine-grained, yellowish-gray, argillaceous sand stone; and rounded-pebble conglomerate; all locally present. Generally the limestone is in the lower one third to one-half of the unit and the dolostone is in the upper two-thirds to one-half of the unit, with a transition zone from one to the other. The Maynardville Formation ranges from 60 to 300 feet in thickness, thinning to the east-northeast from Lee County. Thickness variations may be due in part to grouping of the limestone with the underlying Nolichucky Formation or the dolostone with the overlying Copper Ridge, as noted by Derby (1965).

Cove Creek Limestone and Fido Sandstone (Mississippian) at surface, covers 3 % of this area

Cove Creek Limestone (Butts, 1927). Limestone, argillaceous, light-gray to greenish-gray, thin- to thick-bedded, vsparsely fossiliferous, with thin, brownish laminae; thin beds and zones of medium- to coarse-grained, calcareous sandstone locally present. The Cove Creek Limestone ranges from 1010 to 1220 feet in thickness (Averitt, 1941; Bartlett and Webb, 1971). Fido Sandstone (Butts, 1927). Sandstone, calcareous, reddish-brown to dark-brown, fine- to coarse-grained, thick bedded, cross-bedded, and ripple-marked, fossiliferous, with one or more beds of argillaceous limestone. The Fido Sandstone ranges from 35 to 75 feet in thickness (Averitt, 1941; Bartlett and Biggs, 1980).

Silurian Formations Undivided (Silurian) at surface, covers 3 % of this area

Some landslides with intact stratigraphic units in Giles County area. Includes: Dsu, Skrt, Sm. (Shrc?)

Hancock, Rose Hill, and Clinch Formations (Silurian) at surface, covers 2 % of this area

Hancock Formation (Keith, 1896). Dolomite, limestone, and sandstone. Dolomite, locally calcareous, locally siliceous, light-olive-gray and light-to dark-gray, aphanic to fine-grained, finely-laminated to massive-bedded, locally stromatolitic and vuggy. Lime stone, medium- to dark-gray and bluish-gray, aphanic to fine-grained, laminated to thickbedded, ribbon-banded, mottled, locally emits petroliferous odor when broken. Sandstone, locally calcareous, generally quartzose, medium-grained to pebbly and conglomeratic locally at base of formation; and fine- to medium-grained sandstone locally interbedded with limestone. The formation grades from dolomite with minor limestone and a basal sandstone in southwestern Lee County (Cayuga Dolomite of Miller and Fuller, 1954) to limestone with an underlying or interbedded dolomite with sandstone partings, and a basal sandstone to the northeast and east (Harris and Miller, 1958; Miller and Roen, 1971). The Hancock Formation ranges from 75 to 225 feet in thickness and correlates with the Tonoloway Limestone. Rose Hill Formation . Refer to description under Skrt. Clinch Formation (Safford, 1856). Quartzarenite and shale. Quartzarenite, very-light gray, olive-gray, and brownish- gray with local grayish-red beds, very-fine-grained to very-coarse-grained with local conglomeratic zones, thin- to thick-bedded with thin, green ish-gray and dark-gray shale beds and partings in upper part. Shale, light-olive-gray to gray ish-green; with thin, very fine- to fine-grained sandstone interbeds in the lower one-third to one-quarter of the unit. Erosional unconformity at base of unit identified in northern Lee County (Mill er and Roen, 1973). The Clinch Formation ranges from 220 to 330 feet in thickness. The Division of Mineral Resources uses the name Clinch Formation for exposures in Lee, Wise, and Scott counties where the lower Silurian rocks include the lower Hagan Shale Member and the upper Poor Valley Ridge Sand stone Member. The name Tuscarora Formation is used for the lower Silurianquartzitic sandstone unit in all areas northward in the Valley and Ridge of Virginia, including the Clinch Mountain area where the name Clinch Formation was first used, because of similarity between the Tuscarora and the rocks on Clinch Mountain. In the past many geologists used the name Clinch Sandstone in the southern part of the Valley and Ridge of Virginia and the name Tuscarora Formation in the northern part of the Valley and Ridge of Virginia (Butts, 1940) for essentially the same group of quartzitic sandstones. Dennison and Boucot (1974) and Mill er (1976) described the facies change of the lower Silurian Clinch Sandstone of Southwest Virginia from quartzitic sandstones in the Clinch Mountain belt in Scott and Wise Counties to sandstones and shales in the Lee, southwestern Wise, and western Scott counties area.

Chattanooga Shale and Wildcat Valley Sandstone (Devonian-Mississippian) at surface, covers 2 % of this area

Chattanooga Shale (Hayes, 1891). Shale, siltstone, and sandstone. Shale, carbonaceous, grayish-black to black, fissile to platy, thin- to thick-laminated, locally fossiliferous and pyritic, locally contains phosphatic nodules in the upper part, locally has strong petroliferous odor (Henika, 1988); with beds and zones of medium-gray to greenish-gray, locally silty shale. Siltstone, light-gray to grayish-black, laminated to thick-bedded, locally wavy- and ripple-bedded. Sandstone, light-gray, very-fine-grained. Grayish-black to black, carbonaceous shale comprises 100 percent of the formation in western Lee County and is predominant in the formation throughout southwest Virginia. The Chattanooga Shale uncomformably overlies the Silurian Hancock Formation throughout most of Lee County and the lower Devonian Wildcat Valley Sandstone to the northeast. The Chattanooga Shale ranges in thickness from 200 feet in western Lee County (Englund, 1964) to 1870 feet in northwestern Russell County (Meissner and Miller, 1981). Roen and others (1964) and Kepferle and others (1981) discussed divisions of the Chattanooga Shale and correlation with other units. Wildcat Valley Sandstone (Miller, Harris, and Roen, 1964). Sandstone, limestone, and shale. Sandstone, locally calcareous, locally quartzose, light-gray, grayish-orange, and dark-yellowish-brown, very-fine- to coarse-grained, thin- to massive-bedded, fossiliferous, friable, locally glauconitic; with chert nodules and beds. Locally dark-reddish-brown ironstone replaces sandstone. Limestone, gray, pinkish-gray, and light-brownish-gray, coarse-grained, thick- to massive bedded, sandy, locally present. Shale, yellowish-green to gray, locally present. Where the Wildcat Valley Sandstone is present it uncomformably overlies the Silurian Hancock Formation. The Wildcat Valley Sandstone is absent throughout most of Lee County (Englund, 1964; Harris, 1965; Miller and Roen, 1973) but reaches a maximum of 60 feet in thickness to the northeast (Lower Devonian sandstone of Harris and Miller, 1963).

Juniata, Reedsville, Trenton, and Eggleston Formations (Ordovician) at surface, covers 2 % of this area

Juniata Formation (Darton and Taff, 1896). Siltstone, shale, sandstone, and limestone. Siltstone, shale, and sandstone, locally calcareous, grayish-red, locally fossiliferous; with some interbeds of greenish-gray shale, quartzarenite, and argillaceous limestone. Cycles consisting of a basal, crossbedded quartzarenite with a channeled lower contact; a middle unit of interbedded mudstone and burrowed sandstone; and an upper bioturbated mudstone are commonly present north of New River (Diecchio, 1985). The Juniata Formation ranges from less than 200 to more than 800 feet in thickness. In southwestern Virginia the red, unfossiliferous, and argillaceous Juniata Formation is present in the southeastern belts. It is equivalent to the gray, fossiliferous, and limy Sequatchie Formation of western belts (Thompson, 1970; Dennison and Boucot, 1974). Even though the beds along Clinch Mountain, in Scott County, contain minor amounts of carbonate rock (Harris and Miller, 1958) the majority is grayish- red siltstone, which is typical of the Juniata Formation. Reedsville Shale. Refer to description under Ou. Trenton Limestone. Refer to description under Ou. Eggleston Formation. Refer to description under Ou.

Brallier Formation (Devonian) at surface, covers 2 % of this area

Brallier Formation (Butts, 1918). Shale, sandstone, and siltstone. Shale, partly silty, micaceous, greenish-gray, gray ish-brown and medium- to dark-gray, black, weathers light-olive-gray with light-yellow, brown and purple tints; black shale in thin beds and laminae, sparsely fossiliferous. Sandstone, micaceous, medium-light-gray, very-fine- to fine-grained, thin- to thick-bedded, and light-brown siltstone interbedded with shale. Locally siltstone is in very-thin, nodular, ferruginous lenses (Bartlett, 1974). Lower contact transitional; base at lowest siltstone bed above relatively nonsilty dark-gray shale. Equivalent to part of the Chattanooga Shale. Formation thins southwestward; it ranges from 940 feet in thickness in southwestern Washington County (Bartlett and Webb, 1971) to more than 2200 feet in Augusta County (Rader, 1967).

Hardy Creek Limestone through Dot Limestone (Ordovician) at surface, covers 2 % of this area

Hardy Creek, Ben Hur, Woodway, Hurricane Bridge, Martin Creek, Rob Camp, Poteet, and Dot Limestones (Lee County). Hardy Creek Limestone (Miller and Fuller, 1947). Limestone, light-olive-gray to olive-gray, light- to medium-gray, and brown, micrograined, 1- to 2-inch-thick beds, even-bedded; with interbedded yellowish-gray, argillaceous, limestone; and light-olive-gray, aphanic limestone. Olive-black chert nodules locally abundant. The Hardy Creek Limestone ranges from 75 to 150 feet in thickness. Ben Hur Limestone (Miller and Brosgé, 1950). Limestone, argillaceous, yellowish-gray, light-olive-gray, light-brown, and light-gray, micrograined, thin-bedded; some beds composed of fossil detritus in middle of unit; and some beds of coarsegrained limestone. The Ben Hur Limestone ranges from 95 to 165 feet in thickness. Woodway Limestone (Miller and Brosgé, 1950). Limestone, light-olive-gray to olive-gray and light-brownish-gray to brownish-gray, micrograined, thin-bedded, even-bedded; interbedded with olive-gray to olive-black, medium-grained, wavy-bedded limestone; and sparse zones of argillaceous limestone. Thin limestone beds composed of fossils locally abundant at base of unit. Locally abundant olive-black chert nodules. The Woodway Limestone ranges from 240 to 400 feet in thickness. Hurricane Bridge Limestone (Miller and Brosgé, 1950). Limestone, light-gray and light-olive-gray to olive-gray, thin-bedded, micrograined, yellowish-gray; with intervals of interbedded grayish-red, argillaceous, micrograined limestone; and light-olive-gray, thick-bedded, micrograined limestone. Dark-gray chert zones locally present. The Hurricane Bridge Limestone ranges from 200 to 370 feet in thickness. Martin Creek Limestone (Miller and Brosgé, 1950). Limestone, light-olive-gray to dark-olive-gray, locally with abundant fossil fragments, me ium-grained; and light-olive gray to dark-olive-gray, micrograined limestone; with locally abundant olive-black chert nodules. A fine- to coarse-grained limestone that is a maximum 35 feet thick is locally present. Locally the dark colored, medium-grained limestone emits a petroliferous odor when broken. The Martin Creek Limestone ranges from 40 to 180 feet in thickness. Rob Camp Limestone (Miller and Brosgé, 1950). Limestone, light-olive-gray, thin- to massive-bedded, micrograined, with patches of white calcite ("birds-eyes") and very sparse chert nodules. The Rob Camp Limestone ranges from discontinuous (where cut out by post-depositional erosion) to a maximum 150 feet in thickness (Miller and Brosgé, 1954). Poteet Limestone (Miller and Brosgé, 1950). Limestone, grades from light-olive-gray and medium-gray, micrograined limestone; interbedded with argillaceous, yellowish-gray, micrograined limestone in the southwest; to dark-gray, medium grained limestone; overlain by interbedded light-olive-gray, micrograined limestone, and argillaceous limestone in the northeast. Locally abundant olive-black chert nodules. Generally thin- to medium-bedded. The Poteet Limestone ranges from 45 to 110 feet in thickness. Dot Limestone (Miller and Brosgé, 1950). Limestone, dolomite, and shale. Limestone, light-olive-gray, micrograined, thin- to medium-bedded, locally dolomitic. Dolostone, argillaceous, conglomeratic (pebbles and cobbles derived from underlying dolomite and chert), grayish-red, yellowish-gray, and very-light- to medium-gray, micro-grained, grades into overlying limestone. Shale, dolomitic to calcareous, very light-to light-gray, interbedded with limestone and dolomite beds. One or more chert zones may be locally present near top of unit. Generally lower contact is represented by an unconformity overlain by the conglomeratic dolomites. The Dot Limestone ranges from 70 to 220 feet in thickness.

Mascot and Kingsport Dolomites (Ordovician) at surface, covers 2 % of this area

Mascot Dolomite (Rodgers, 1943). Dolostone and limestone. Dolostone, nearly white or very-light- to medium gray with red- to pink-streaks, very-fine- to fine-grained; with subordinate medium- to coarse-grained dolostone; thin green shale partings; sandstone lenses to 1-foot thick; and grayish red and dark-gray dolostones; all locally present. Dense, gray limestone is in the lower half and chert is present locally. Unconformable (locally angular) upper contact. The Mascot Dolomite ranges from 330 to 640 feet in thickness. Kingsport Dolomite (Rodgers, 1943). Dolostone and limestone. Dolostone, very-light-gray to dark-gray and light- to dark-brown, fine- to coarse-grained; with white chert; thin green shale partings; sandstone lenses; and scattered sand grains. Fine-grained limestone is locally present. The Kingsport Dolostone ranges from 100 to 350 feet in thickness. The Longview Limestone of previous reports is included in the Kingsport (Harris, 1969).

Maccrady Shale and Price Formation (Mississippian) at surface, covers 1 % of this area

Maccrady Shale and Price Formation. Refer to individual units for descriptions.

Upper and Middle Ordovician Formations Undivided (Ordovician) at surface, covers 0.6 % of this area

Includes: Oun, Ous, Ou, Om, Okpl, Oeln, Oml, Ols.

Millboro Shale, Huntersville Chert, and Rocky Gap Sandstone (Devonian) at surface, covers 0.6 % of this area

Millboro Shale, Huntersville Chert, and Rocky Gap Sandstone. Millboro Shale. Refer to previous description under Dmn. Huntersville Chert (Price, 1929). Chert, white, thin-bedded, iron-stained, blocky, fossiliferous with cherty, glauconitic sandstone and greenish-gray shale. The Huntersville Chert ranges from 10 to 60 feet in thickness (Bartlett and Webb, 1971). Butts (1940, p. 303) states, "The Onondaga [Huntersville Chert] persists to Mendota, Washington County, but 10 miles farther southwest it is absent in a fully exposed section". The Huntersville correlates with the Needmore Formation to the northeast and the upper part of the Wildcat Valley Sandstone in Lee County. Rocky Gap Sandstone (Swartz, 1929): Sandstone, medium- to light-gray, weathers dark-yellowish-orange, coarse-grained, scattered, thin, quartz-pebble conglomerate beds, arenaceous chert in upper ten feet, calcite cement, friable when weathered. Thickness ranges from 0 near McCall Gap, Washington County to about 85 feet in Bland and Giles counties. Equivalent in part to the Wildcat Valley Sandstone of Lee County and the Ridgeley (Oriskany) Sandstone and Helderberg Group north of Craig County. The lower contact is disconformable. The upper contact with the Huntersville Chert appears to be conformable.

Norton Formation (Pennsylvanian) at surface, covers 0.4 % of this area

Norton Formation (Campbell, 1893). Siltstone, shale, sandstone, conglomerate, limestone, and coal. Siltstone and shale, light- to medium-gray, with siderite and claystone concretions, fossiliferous; interbedded with and grades into sandstone. Sandstone, feldspathic, micaceous, argillaceous, light- to medium-gray, very-fine- to coarse-grained, thin- to very-thick-bedded, cross-bedded, locally massive, well-cemented. Conglomerate in thin zones in McClure Sandstone Member (lateral equivalent to part of Bee Rock Sandstone Member of the Lee Formation). Lime stone, medium-gray, micrograined, locally in lenses in two zones above the McClure Sandstone Member (Taylor, 1989; Whitlock, 1989). Coal in several beds and zones. A volcanic ash parting is in the Upper Banner coal bed locally (Diffenbach, 1988, 1989; Evans and Troensegaard, 1991; Henika, 1989a). The base of the Norton is defined as the top of the uppermost quartzarenite of the Lee Formation. On the western side of the coalfield the base of the Norton is at the top of the Bee Rock Sandstone Member of the underlying Lee Formation. However, the Bee Rock grades eastward into feldspathic, conglomeratic sandstone of the McClure Sandstone Member of the Norton. Several underlying Lee quartzarenites successively tongue out or grade into finer-grained clastic rocks to the southeast stratigraphically lowering the base of the Norton. This accounts for the great range in thickness of 500 to 2480 feet for the Norton Formation.

Sequatchie Formation, Reedsville Shale, Trenton Limestone, Eggleston Formation (Ordovician) at surface, covers 0.4 % of this area

Sequatchie Formation (Ulrich, 1913). Siltstone, limestone, and shale. Siltstone, calcareous, medium-gray to grayish-red, maroon, and green, even and wavy thin-beds. Limestone, argillaceous, gray, greenish-gray, and grayish-red to dusky-red, nodular, in 1-inch to 3-feet thick planar beds. Shale, grayish-red. Percentage of each lithotype varies throughout the lateral and vertical extent of the formation. The Sequatchie Formation ranges from 250 to 440 feet in thickness. Laterally equivalent to the Juniata Formation. Reedsville Shale (Ulrich, 1911). Shale, siltstone, and minor limestone. Shale, locally silty, calcareous, yellowish gray, grayish-olive, greenish-gray, and medium-gray. Siltstone, calcareous, greenish-gray to olive-gray, in 1- to 2-inch thick planar beds. Limestone, medium- to dark-gray, fine- to coarse-grained, fossiliferous, in 6-inch thick beds; and silty to argillaceous, medium-light-gray to medium-dark-gray and olive-gray, micrograined to medium-grained limestone, generally in 1- to 2-inch thick planar beds. A few very-fine grained sandstone beds are present within the unit. The shales are predominant throughout most of southwestern Virginia (Miller and Brosgé, 1954; Miller and Fuller, 1954). Siltstones and limestones are subordinate to and interbedded with the shales. The Reedsville Shale ranges from 275 feet in Lee County to approximately 1000 feet in Frederick County. It is equivalent to the upper Martinsburg of previous reports in western Virginia and is conformable with the underlying Trenton Limestone and Dolly Ridge Formation. Trenton Limestone (Vanuxem, 1838). Limestone, medium-light-gray to dark-gray and brownish-gray, micrograined to medium-grained, fossiliferous, thin- to medium-bedded, wavy- to platy-bedded with grayish-yellow and dark-gray shale partings, minor olive-black chert nodules; and one bentonite bed noted in western Scott County (Harris and Miller, 1958). (See Eggleston Formation description for additional discussion of the bentonite beds). Locally some of the dark-colored beds emit a petroliferous odor when broken. The Trenton Limestone ranges from 300 to 600 feet in thickness. Eggleston Formation (Matthews, 1934). Mudstone, siltstone, limestone, and bentonite. Mudstone and siltstone, light-gray, greenish-gray and yellowish-gray, locally contains gray and white mottled calcite patches and stringers. Limestone, light-olive-gray to olive-gray and light-brown, aphanic to medium-grained, thin-bedded; with argillaceous, yellowish-gray, micrograined to medium-grained limestone. Two thick (1-3 feet), greenish-gray, bentonite beds in upper part of unit. Olive-black chert nodules are locally present. Mudstone is dominant in lower and locally in upper part; light-olive-gray to olive-gray limestone is dominant in middle part of unit. The Eggleston Formation ranges from 125 to 180 feet in thickness. Haynes (1992) reported on three K-bentonite beds in the Trenton and Eggleston Limestones and the Moccasin Formation in the Valley and Ridge Province of southwest Virginia. The uppermost K-bentonite bed has not been correlated regionally and is known locally as the V-7. The lower two K-bentonite beds have been identified from regional correlations as the Deicke K-bentonite overlain by the Millbrig K-bentonite.

Lower Devonian and Silurian Formations Undivided (Silurian-Devonian) at surface, covers 0.3 % of this area

Some landslides with intact stratigraphic units in Craig County area. Includes: Dsu, Skrt, Sm. (Shrc?)

Silurian and Upper Ordovician Formations Undivided (Ordovician-Silurian) at surface, covers 0.1 % of this area

Includes: Skrt, Sm, Oun, Ous, Ou, Om. (Shrc and Okpl?)

Keefer, Rose Hill, and Tuscarora Formations (Silurian) at surface, covers < 0.1 % of this area

Keefer Sandstone (Ulrich, 1911). Sandstone, light-gray, fine-grained, cross-laminated, medium-bedded, very resistant. Thins northward and southwestward from a maximum of over 300 feet in Craig and western Botetourt counties. To the north it appears to interfinger with the Wills Creek and McKenzie Formations. The Keefer is equivalent to the upper portion of the Massanutten Sandstone. (The Keefer Sandstone, as used in this report, includes all of the quartzarenites with minor Skolithus-bearing red sand stone and minor calcite cemented quartzarenite in the interval above the Rose Hill Formation and below the Tonoloway Limestone in Botetourt, Rockbridge, and Augusta counties between Eagle Rock and Augusta Springs (Lampiris, 1976). Rose Hill Formation (Swartz, 1923). Sandstone, dark grayish-red, fine- to coarse-grained, poorly-sorted, argillaceous; hematite cemented, quartz sandstone interbedded with red or yellowish-green clay shale and greenish-gray, fine-grained sandstone. It is largely siltstone and shale with minor sandstone and thin limonitic iron ore beds in Southwest Virginia. Conformable with the underlying Tuscarora Formation, the Rose Hill Formation ranges up to 500 feet in thickness in northern and western Virginia but pinches-out in southwest ern Botetourt and Roanoke counties where the Keefer and Tuscarora For ma tions merge. It is present with other Silurian rocks everywhere except in the Massanutten Mountains or where an unconformity exists in exposures east of Walker Mountain. Tuscarora Formation (Darton and Taff, 1896). Quartzite, quartzarenite, and minor shale. Quartzite, light-gray with few nearly white, porcelaneous beds, fine- to medium-grained, with quartz-pebble conglomerate locally near base, quartz cemented, thick-bedded, and cross-bedded, resistant, cliff- and ledge-former, generally not more than 75 feet thick, comprises entire unit in many areas or is upper member where unconformably overlying a lower quartzarenite and shale member. Quartzarenite, light-yellowish-brown or medium-gray, fine-grained, thin-bedded, ranges in thickness from 0 to 175feet. Shale, light- to medium-brownish-gray, arenaceous, thin interbeds in quartzarenite. Conformably overlies the Juniata Formation in central western Virginia. Where lower member is absent the upper member unconformably overlies the Juniata, Oswego, Martinsburg, or Reedsville Formations or may be conformable with the Juniata Formation in northern Virginia. In southwestern Virginia grayish-red, fine-grained, ferruginous sandstone with lenses of coarse-grained, quartz sandstone and quartz-pebble conglomerate are included in the upper part of the formation. The Tuscarora is equivalent to the Clinch Formation and to the lower part of the Massanutten Sandstone.

Maynardville Limestone, Nolichucky Shale, Honaker Dolomite, Maryville Limestone, Rogersville Shale, Rutledge Limestone, Pumpkin Valley Shale (Cambrian) at surface, covers < 0.1 % of this area

Maynardville Limestone - Thick-bedded, bluish-gray, ribboned (silt and dolomite) nodular limestone; light-gray, fine-grained, laminated to thinly bedded, noncherty dolomite in upper part. Thickness 150 to 400 feet; Nolichucky Shale - Pastel-colored (pink, greenish, olive), flaky clay shale; gray, commonly oolitic, shaly limestone lenses; locally stromatolitic limestone layers; thin, blocky siltstone near middle. Thickness 100 feet in the east to 900 feet in the west; Honaker Dolomite - Dark-gray, medium-bedded dolomite with minor dark limestone beds; locally cherty; cryptozoans abundant in places. Thickness about 1,500 feet; Maryville Limestone - Gray, ribboned (silt and dolomite), fine-grained, evenly bedded limestone; intraformational conglomerate and oolitic layers common; clay shale and light-gray dolomite locally. Thickness 300 to 800 feet; Rogersville Shale - Light-green, fissile clay shale; in places limestone (Craig Member) in upper part. Commonly 25 to 80 feet thick; maximum thickness 250 feet; Rutledge Limestone - Medium- to dark-gray, ribboned (silt and dolomite), medium-grained, well-bedded limestone; locally dark-gray, coarse-grained, medium-bedded dolomite in upper part. Thickness 100 to 500 feet; Pumpkin Valley Shale - Dull-brown to maroon shale with numerous interbeds of thin, blocky, and sandy siltstone. Thickness 100 to 600 feet.

Copper Ridge Dolomite (Ordovician) at surface, covers < 0.1 % of this area

Coarse, dark-gray, knotty dolomite, asphaltic in places; with much gray, medium-grained, well- bedded dolomite; abundant chert; cryptozoans typical. Thickness about 1,000 feet.

Chepultepec Dolomite (Ordovician) at surface, covers < 0.1 % of this area

Light-gray, fine-grained, well-bedded dolomite, moderately cherty; fine-grained limestone locally in upper part; quartz sandstone beds at base. Thickness about 800 feet.

Maynardville Limestone (Cambrian) at surface, covers < 0.1 % of this area

Thick-bedded, bluish-gray, ribboned (silt and dolomite) nodular limestone; light-gray, fine-grained, laminated to thinly bedded, noncherty dolomite in upper part. Thickness 150 to 400 feet.