USGS Visual Identifier
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Geologic Unit: Clays Ferry

Clays Ferry Formation (KY*,IN*,OH*)
Clays Ferry Formation of Cincinnati group (informal) (OH)
For informal usage, the rank or lithologic term should not be capitalized.

Ordovician, Middle*
Ordovician, Late*
Geologic Province:
Cincinnati arch*

Areal Extent:

Type Locality:
Type section: South of Kentucky River in gully a few tens of feet northeast of I-75 bridge over river and in roadcuts on northeast side of I-75, Ford quadrangle, Madison Co., KY (Weir and others, 1965).

Point Pleasant Tongue (KY*,IN*,OH*)

Unit Name History:
Named (Weir and others, 1965).
Age modified locally (Wolcott, 1969) [From GNC index card files; not synopsized].
Revised (W.C. Swadley and others, 1975, USGS Bull. 1405-A) [Not synopsized].
Extended into IN (John Pojeta, Jr., 1979, USGS Prof. Paper 1066-A, 48 p.) [Not synopsized].
Extended into OH (MacSwinford, 1985) [From GNC index card files; not synopsized].
Assigned to Cincinnati group in OH (Shrake and others, 1988).
Overview; Age modified (Wahlman, 1992).
Not used (Holland, 1993).
Overview (Frey, 1995).

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