Usage:
/Calhoun Coal Member of Mattoon Formation of McLeansboro Group (IL)
[Preoccupied. Name previously applied to Calhoun Limestone by Weller and others [1943] in same area, and Calhoun Shale by Beede (1898) in IA, KS, MO, and NE.]
Geologic age:
Late Pennsylvanian (Missourian)
Type section, locality, area and/or origin of name:
Type locality: in NE/4 NE/4 NE/4 sec. 6, T. 2 N., R. 14 W., Richland Co., southeastern IL. Named from village of Calhoun, 2 mi west of type exposure (Kosanke and others, 1960).
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 ([ ]).