Usage:
Oronto Group of Keweenawan Supergroup (WI*,MI*,MN*)
Subunits:
Copper Harbor Conglomerate (WI*,MI*). Nonesuch Formation/Shale (WI*,MI*). Freda Formation/Sandstone (WI*,MI*).
Geologic age:
Mesoproterozoic*
Type section, locality, area and/or origin of name:
Exposures on Oronto Bay, Iron Co., northwestern WI (Thwaites, 1912).
AAPG geologic province:
Lake Superior region*
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 ([ ]).