Usage:
No current usage.
(†Barnhart Formation (MO) is same as Spechts Ferry Formation of Decorah Group. See Spechts Ferry.)
Geologic age:
Late Ordovician (Mohawkian)
Type section, locality, area and/or origin of name:
Type section: Koch Valley School on U.S. Highway 61-67, 2 mi south of Barnhart, Kimmswick 15-min quadrangle, Jefferson Co., east-central MO (Cooper, 1956).
AAPG geologic province:
Illinois basin
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
Asterisk (*) indicates published by U.S. Geological Survey authors.
"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 conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).