|Geologic age||Upper Devonian|
Sedimentary > Clastic > Mudstone > Shale
Sedimentary > Clastic > Siltstone
|Comments||200-1000 ft. (60-300 m). Secondary unit descriptions from USGS Lexicon website (ref. NY046) and reference NY015:In outcrop in western NY, the Sonyea consists of a basal black shale, the Middlesex Shale Member, and an upper gray shale with limestone nodules, the Cashaqua Shale Member. Members grade eastward into sequence of siltstone and silty shale, which is part of the general turbidite facies of the Catskill delta. The Middlesex is about 65 ft thick in the reference section 0.8 mi south of the village of Middlesex, Yates Co., NY. Thickens eastward to 75 ft at Chidsey Point Gully. Thins westward to 6 ft in Erie Co. Occurs in subsurface of PA, OH, WV, and MD, but is apparently is not present in VA. Makes up most of the Sonyea in the subsurface. The Cashaqua is thin, but recognizable from western NY, through PA and Garret Co., MD, to southwestern WV and has also been identified in southeastern OH. Age is Late Devonian (de Witt and others, 1993). Cashaqua Shale Member of Sonyea Formation extended from southwestern NY into western PA and into subsurface in eastern OH, WV, and westernmost MD (Garrett Co.) (de Witt and others, 1993).|
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.
de Witt, Wallace, Jr., Roen, J.B. and Wallace, L.G., 1993, Stratigraphy of Devonian black shales and associated rocks in the Appalachian basin, IN Roen, J.B., and Kepferle, R.C., eds., Petroleum geology of the Devonian and Mississippian black shale of eastern North America: U.S. Geological Survey Bulletin, 1909-B, p. B1-B57.
USGS Geologic Names lexicon found at: http://ngmdb.usgs.gov/Geolex/
|Counties||Broome - Chemung - Chenango - Cortland - Livingston - Ontario - Schuyler - Seneca - Steuben - Tioga - Tompkins - Yates|