No current usage?
(†West Ledge Formation (SD) considered abandoned? Uncertain if used by the SD Geol. Survey. Abandoned by the USGS.)
Precambrian
Not designated (Hosted and Wright, 1923).
Midcontinent region
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 ([ ]).