U.S. Geological Survey Home AASG Logo USGS HOME CONTACT USGS SEARCH USGS
National Geologic Map Database
Map showing publication footprint
  • Usage in publication:
    • Penn Yan tongue
  • Modifications:
    • Named
  • Dominant lithology:
    • Shale
  • AAPG geologic province:
    • Appalachian basin
Publication:

Grossman, W.L., 1944, Stratigraphy of the Genesee group of New York: Geological Society of America Bulletin, v. 55, no. 1, p. 46-76.


Summary:

Proposed the name Penn Yan tongue for lower shales of West River shale. Lower part consists of interbedded black and blue-black shales, blue-gray shales and thin limy argillaceous beds; unfossiliferous flags interbedded in dark shales. In upper part, shales are generally lighter colored and more fossiliferous. Concretions are plentiful; marcasite nodules present. Unit is about 140 ft thick in type area but thins eastward. Contact with underlying Geneseo shale is difficult to place but is placed at base of sequence of dark limy shales and interbedded shaly limestone layers. Top of formation is placed arbitrarily at base of Crosby lentil of Starkey tongue, although Starkey-type flags begin lower.

Source: GNU records (USGS DDS-6; Reston GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Penn Yan Shale Member*
  • Modifications:
    • Areal extent
    • Age modified
  • AAPG geologic province:
    • Appalachian basin
Publication:

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.


Summary:

Penn Yan Shale Member of Genesee Formation extended from southwestern NY into western PA. West of Canandaigua Lake in western NY, the boundary between the Middle and the Upper Devonian lies within the lower part of the Penn Yan. Unit consists mainly of dark- to medium-gray shale or mudrock and some beds of black shale, abundant limestone nodules, and a few thin beds of dark-gray siltstone. The Penn Yan is overstepped to the southwest along the Middle Devonian unconformity by the West River Shale Member. To the east of Canandaigua Lake, the Penn Yan and the West River grad laterally into the Sherburne Flagstone and Ithaca Members.

Source: GNU records (USGS DDS-6; Reston GNULEX).


For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.

Asterisk (*) indicates usage by the U.S. Geological Survey. Other usages by state geological surveys.

"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).

Slash (/) indicates name does not conform with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005). This may be explained within brackets ([ ]).