Usage:
No current usage.
(†Calhoun Limestone (IL) considered abandoned. Replaced with Bonpas Limestone Member of Mattoon Formation of Mcleansboro Group. See Bonpas.)
Geologic age:
Late Pennsylvanian (Missourian)
Type section, locality, area and/or origin of name:
Named from Calhoun, Richland Co., southeastern IL (Weller and others [1943]).
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 ([ ]).