Usage:
Umlor formation [informal] of Prairie du Chien Group (MI-subsurface)
Considered informal until formally published. The rank or lithologic term should not be capitalized.
Geologic age:
Early Ordovician
Type section, locality, area and/or origin of name:
Not designated. Occurs in central MI.
AAPG geologic province:
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 ([ ]).