No current usage.
(†Herrin Limestone of Carbondale Group (IL-local) replaced with Brereton Limestone Member of Carbondale Formation. See Brereton.)
Pennsylvanian
Named because of its association with Herrin coal. First described in Saline Co., southern IL.
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 ([ ]).