Usage:
Eau Claire Formation (IL*,IN*,KY*,MN*,MO)
Eau Claire Formation of Elk Mound Group (WI)
Eau Claire Formation of Knox Group (IL-notably in southern part)
Eau Claire Formation of Munising Group of Potsdam Supergroup (IN-subsurface)
Eau Claire Formation of Munising Group (MI-subsurface)
Eau Claire Sandstone (IL*,IN*,IA*,MI*,MN*,OH*)
Eau Claire Sandstone of Dresbach Group (IA*,MI*,MN*,OH*,WI*)
Eau Claire Sandstone of Elk Mound Group (WI)
Geologic age:
Middle to Late Cambrian (Croixan; Lincolnian to Millardan; Marjuman to Steptoean)*
Type section, locality, area and/or origin of name:
Named from exposures at mouth of Eau Claire River, near City of Eau Claire, Eau Claire Co., western WI (US geologic names lexicons, USGS Bull. 896, 1200).
AAPG geologic province:
Cincinnati arch*
Illinois basin*
Iowa shelf*
Lincoln anticline
Michigan basin*
Sioux uplift*
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 ([ ]).