Usage:
Prairie du Chien Group (IL*,IN*,IA*,MI*,MN*,OH*,WI*)
Prairie du Chien Group of Knox Supergroup (IN-subsurface)
Subunits:
(alphabetical): Gunter Sandstone (IL), New Richmond Sandstone (IL*,IA,MI*,MN*,WI*), Oneota Dolomite (IN,IA*,IL*,MI*,MN*,WI*) or Oneota Formation (WI), Shakopee Dolomite (IA*,IL*,IN,MI*,MN*,WI) or Shakopee Formation (IA,MN*,WI), Umlor formation [informal] (MI), [?]Foster Formation (MI).
Geologic age:
Early Ordovician (Ibexian; Tremadocian)*
Type section, locality, area and/or origin of name:
Type area: exposures in vicinity of Prairie du Chien, WI (Bain, 1906).
AAPG geologic province:
Cincinnati arch*
Iowa shelf*
Michigan basin*
Wisconsin arch*
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 ([ ]).