USGS Visual Identifier
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Geologic Unit: Reedsville

Reedsville Formation (PA,VA,WV)
Reedsville Shale (PA*,TN*,VA*,WV*,OH*)
Reedsville Shale of Chickamauga Group (TN)

Ordovician, Late*
Edenian, middle*

Geologic Province:
Appalachian basin*

Areal Extent:

Type Locality:
Exposures at Reedsville, Mifflin Co., central PA (Ulrich, 1912).

Unit Name History:
Named (Ulrich, 1911). Overview in PA (Butts, 1936). Revised (Kay, 1944). Extended into TN (Rodgers, 1953). Revised to Reedsville Formation (Conlin, 1962). Included in Chickamauga Group (Harris, 1965). Extended into WV (Patchen, 1967). Isotopic dating (Lapham, 1971). Overview (Dean and others, 1985). Overview (Faill and others, 1989). Revised; Age modified; Extended into OH subsurface (Ryder, 1992).

Note: If you need more information, please contact Nancy Stamm (
Asterisks (*) indicate usage by the U.S. Geological Survey. Other usages by state geological surveys.

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

Slashes (/) indicate unit name usage violates the 1983 North American Stratigraphic Code. This violation may be explained within brackets ([ ]).

U.S. Department of the Interior, U.S. Geological Survey, Reston, VA, USA
Database project personnel
Last modified: 15-Jan-2013