Knobs Formation, Paperville Shale, Lenoir and Mosheim Limestone

Knobs formation (Cooper, 1961). Shale, siltstone, sandstone, and conglomerate. Shale and siltstone, brown. Sandstone, lithic, greenish-brown, fine- to coarse-grained. Conglomerate, polymictic (rounded to subrounded clasts of limestone, dolomite, sandstone, quartzite, vein quartz, shale, chert, and feldspar in calcareous matrix). Some interbeds of calcareous siltstone and sandstone. The Knobs formation ranges from 800 to 3400+ feet in thick ness (the upper part of the unit is eroded) (Bartlett and Biggs, 1980). The Knobs formation corresponds to the upper member of the Athens Shale of Butts (1933) as described by Bartlett and Biggs (1980). Fincastle Conglomerate Member of the Martinsburg Formation. Conglomerate, sandstone, shale, and siltstone (Rader and Gathright, 1986). Conglomerate (type 1), poorly sorted, clast-supported, pebble to boulder clasts of limestone, dolomite, quartzite, sandstone, chert, vein quartz, granite gneiss, quartz pebble conglomerate, greenstone, and shale, subangular to subrounded. Conglomerate (type 2), poorly-sorted, matrix supported clasts of quartzite, vein quartz, limestone, and chert, subrounded to well-rounded. Matrix framework grains in both types are sand-size quartz, limestone, and dolomite with minor chlorite and sericite. The cement is calcite. The conglomerate fines upward from a scoured base to sandstone. Sandstone, lithic, medium- to very-coarse-grained, brownish-gray, cross stratification rare. Shale and siltstone, gray, convolute bedding common. This member is restricted to the Fincastle area of Botetourt County. Paperville Shale (Cooper, 1956). Shale, olive-gray to dark-gray, fissile, thin-bedded; with minor gray, argillaceous siltstone, fossiliferous in lower part. The Paperville Shale ranges from 200 to 2300 feet in thickness (Bartlett and Biggs, 1980). The Paperville Shale corresponds to the lower member of the Athens Shale of Butts (1933) as described by Bartlett and Biggs (1980). Lenoir Limestone (Safford and Killibrew, 1876). Limestone, argillaceous, gray to dark-gray, fine-grained, medium bedded, silty laminations, fossiliferous. Lower contact is unconformable. The Lenoir Lime stone ranges from 0 to 70 feet in thickness (Bartlett and Biggs, 1980). Mosheim Limestone (Ulrich, 1911). Limestone, aphanic, medium-bedded with calcite crystal clusters, sparsely fossiliferous; limestone-dolomite-chert clasts in aphanic limestone matrix common at base of unit; rare thin interbedded dolomite. Unconformable with underlying unit. The Mosheim Limestone ranges from 0 to 150 feet in thickness (Bartlett and Biggs, 1980). The Lenoir and Mosheim Limestones have a combined thickness up to 270 feet in southwestern Washington County (Bartlett and Webb, 1971). In the Fincastle Valley the nomenclature Lincolnshire and New Market Limestones replaces Lenoir and Mosheim Limestones of older reports.
State Virginia
Name Knobs Formation, Paperville Shale, Lenoir and Mosheim Limestone
Geologic age Ordovician
Lithologic constituents
Major
Sedimentary > Clastic > Sandstone
Sedimentary > Clastic > Conglomerate
Sedimentary > Clastic > Siltstone
Minor
Sedimentary > Carbonate > Limestone
Sedimentary > Clastic > Mudstone > Shale > Black-shale
Incidental
Sedimentary > Chemical > Chert
Comments In Fincastle Valley (Botetourt County) the Knobs Formation represented by Fincastle Conglomerate and Martinsburg Formation; Appalachian Plateaus and Valley and Ridge
References

Virginia Division of Mineral Resources, 1993, Geologic Map of Virginia: Virginia Division of Mineral Resources, scale 1:500,000.

Virginia Division of Mineral Resources, 2003, Digital Representation of the 1993 Geologic Map of Virginia, Publication 174, CD ROM (ISO-9660) contains image file, expanded explanation in pdf, and ESRI shapefiles, scale 1:500,000.

NGMDB product
Counties Botetourt - Washington - Wythe - Bristol