Geologic units in Russell county, Virginia

Additional scientific data in this geographic area

Knox Group (Cambrian-Ordovician) at surface, covers 23 % 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.

Moccasin or Bays Formation through Blackford Formation (Ordovician) at surface, covers 16 % 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 Honaker Formations (Cambrian) at surface, covers 16 % 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.

Norton Formation (Pennsylvanian) at surface, covers 10 % 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.

Juniata, Reedsville, Trenton, and Eggleston Formations (Ordovician) at surface, covers 9 % 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.

Rome Formation (Cambrian) at surface, covers 8 % 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.

Kanawha Formation (Pennsylvanian) at surface, covers 4 % of this area

Kanawha Formation (Campbell and Mendenhall, 1896). Sandstone, siltstone, shale, coal, and underclay. Sandstone, feldspathic, micaceous, with dark mineral grains, light- to medium-gray, fine- to coarse-grained, upper beds locally conglomeratic, lenticular, thick-bedded to massive, cross-bedded. Siltstone and shale, medium- to dark-gray, even-bedded, interbedded with sandstone, coal, and medium-gray underclay. Base of formation conformable, placed at the bottom of Kennedy coal bed overlying McClure Sandstone Member of New River Formation (Englund, 1981; Meissner and Miller, 1981; Windolph, 1987). Equivalent to the Wise Formation and upper part of the Norton Formation. Thickness: 550 + feet (J.E. Nolde, personal communications, 1993); top part eroded.

Mississippian Formations Undivided (Mississippian) at surface, covers 3 % 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.

New River Formation (Pennsylvanian) at surface, covers 2 % of this area

New River Formation (Fontaine, 1874; redefined by Read and Mamay, 1964). Sandstone, siltstone, shale, coal, underclay, and limestone. Sandstone, feldspathic, micaceous, disseminated dark mineral grains, light- to medium-light-gray, very-fine- to coarse-grained, locally conglomeratic with quartz pebbles as much as 3 inches in diameter, thin- to thick-bedded, locally massive, ripple-bedded, cross-bedded; contains carbonaceous fragments. Siltstone, medium-light- to medium-gray, even-bedded, ripple-bedded, deformed locally. Shale, medium- gray to black, evenly to indistinctly bedded, with few very fissile carbonaceous beds, plant fossils, ironstone laminations and concretions. Coal, finely cleated, impure coal partings in several beds, locally grades into black carbonaceous shale. Underclay, medium-gray, clayey to silty, contains root casts. Limestone, medium-gray, argillaceous, in thin discontinuous beds and ellipsoidal concretions locally occurs near base and middle part of formation. Marine invertebrate fossils locally in basal bed. Base is conformable with Pocahontas Formation and placed at bottom of Pocahontas No. 8 coal bed in most outcrop areas (Englund and Thomas, 1990). Northwest of outcrop belt, base is unconformable with the underlying Pocahontas Formation. The New River is thickest in western Tazewell and eastern Buchanan counties (Englund, 1981); it ranges from 1380 to 1925 feet in thickness.

Norton, New River, Lee and Pocahontas Formations Undivided (Pennsylvanian) at surface, covers 2 % of this area

Norton Fm: siltstone, shale, sandstone, conglomerate, limestone, and coal. New River Fm: sandstone, siltstone, shale, coal, underclay, and limestone. Lee Fm: quartzarenite, conglomerate, sandstone, shale, siltstone, and coal. Pocahontas Fm: sandstone, siltstone, shale, underclay, and coal.

Silurian Formations Undivided (Silurian) at surface, covers 2 % of this area

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

Chattanooga Shale and Wildcat Valley Sandstone (Devonian-Mississippian) at surface, covers 1 % 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).

Silurian and Upper Ordovician Formations Undivided (Ordovician-Silurian) at surface, covers 1 % of this area

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

Lee Formation (Pennsylvanian) at surface, covers 0.8 % 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).

Lower Ordovician and Upper Cambrian Formations Undivided (Cambrian-Ordovician) at surface, covers 0.7 % of this area

Includes Pinesburg Station Dolomite, Rockdale Run Formation, Beekmantown Formation, Stonehenge Limestone, and Conococheague Formation. Refer to descriptions under Ob and O[co/[co.

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 0.1 % 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.

Maccrady Shale and Price Formation (Mississippian) at surface, covers < 0.1 % of this area

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

Wise Formation (Pennsylvanian) at surface, covers < 0.1 % of this area

Wise Formation (Campbell, 1893) . Sandstone, siltstone, shale, limestone, coal, and underclay. Sandstone, lithic, feldspathic, micaceous, argillaceous, carbonaceous locally, light- to medium-gray to moderate- and pale-yellow- brown, fine- to coarse-grained, locally pebbly, thin- to thick-bedded, cross-bedded to even-bedded, locally massive, well-cemented; contains fragments of shale, siltstone, and carbonized plant fossils locally. Siltstone and shale, light olive- gray, medium- to dark-gray and grayish-black, contains siderite ironstone in very-thin beds and nodules, carbonized plant fossils; invertebrate fossils in dark-gray to black shale and micrograined limestone in the upper part of formation (Miller, 1969; Miller and Roen, 1973; Nolde, Henderson, and Miller,1988; Nolde, Whitlock, and Lovett, 1988a). Limestone, medium- to dark-gray, micrograined, in very-thin lenses and beds in shale and siltstone in two to three zones in lower part of formation (Taylor, 1989; Whitlock, Lovett, and Diffenbach, 1988). Coal interbedded with shale, siltstone, and sandstone. Underclay, light-gray, root casts, beneath coal; as much as 5 feet thick under the Williamson coal bed in Buchanan County (Henika, 1989b). A dark-gray to brownish-gray, flint clay in the Phillips (Fire Clay; No.7) coal bed in northern Lee County (Miller and Roen, 1973) and western Wise County is a volcanic ash deposit (Seiders, 1965) that covers parts of Kentucky, Tennessee, Virginia and West Virginia; it has been dated at an age of 311 - 312 million years (Lyons and others, 1992; Rice and others, 1990). Base of formation at bottom of Dorchester coal bed. Thickness 2150 to 2268 feet.

Greenbrier Limestone (Mississippian) at surface, covers < 0.1 % 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.