|Geologic age||Upper Ordovician|
Sedimentary > Clastic > Sandstone
|Comments||part of Lorraine, Trenton, and Black River Groups up to 4500 ft. (1400 m). Secondary unit descriptions from USGS website (ref. NY046) and references NY034 and NY01: The Oswego Formation in northwestern VA consists of greenish gray, brown weathering, fine-grained sandstone, tan shale, and conglomerate. Overlies the Martinsburg Formation and underlies the Juniata Formation. The combined thickness of the Oswego with the Juniata is 450 to 500 feet. The Oswego and Juniata intertongue and in places the Oswego underlies the Tuscarora Formation (Rader and Briggs, 1976), In cross section E-E'. Area of coverage is subsurface of central West Virginia and northern Virginia. Oswego Sandstone used in Allegheny structural front for argillaceous sandstone overlying Reedsville Formation. Pre-Silurian erosion has removed it from areas between North Mountain thrust fault to Blue Ridge. Age is Late Ordovician (latest Maysvillian through earliest Richmondian) based on fossils (Ryder, 1992).|
Fisher, D.W., Isachsen, Y.W., and Rickard, L.V., 1970, Geologic Map of New York State, consisting of 5 sheets: Niagara, Finger Lakes, Hudson-Mohawk, Adirondack, and Lower Hudson, New York State Museum and Science Service, Map and Chart Series No. 15, scale 1:250,000.
Ryder, R.T., 1992, Stratigraphic framework of Cambrian and Ordovician rocks in the central Appalachian basin from Morrow County, Ohio, to Pendleton County, West Virginia, IN Evolution of sedimentary basins; Appalachian basin: U.S. Geological Survey Bulletin, 1839-G, p. G1-G25.
Rader, E.K. and Biggs, T.H., 1976, Geology of the Strasburg and Toms Brook quadrangles, Virginia: Virginia Division of Mineral Resources Report of Investigations, no. 45, 104 p.
USGS Geologic Names lexicon found at: http://ngmdb.usgs.gov/Geolex/