No current usage.
(†Richmond Group has been abandoned as a lithostratigraphic term, and has been used as a chronostratigraphic term (Richmondian Stage) for some time. To prevent confusion, the use of Richmond as a lithostratigraphic term should be avoided.)
Ordovician, Late
Cincinnatian
Named from Richmond, IN (Winchell and Ulrich, 1897).
Cincinnati arch
Illinois basin
Ozark uplift
Michigan 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 ([ ]).