Bergland Group of Keweenawan Supergroup (MI*,WI*)
Portage Lake Volcanics (MI*,WI*), Porcupine Volcanics (MI*,WI*).
Mesoproterozoic*
Type area: north and northeast of Bergland, in T. 49 N., R. 42 W., Ontonagon Co., northwestern MI (Upper Peninsula) (Cannon and Nicholson, 1992).
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 ([ ]).