USGS Visual Identifier
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Geologic Unit: Keweenawan

Keweenawan Supergroup (MI*,WI*,MN*)

Proterozoic, Middle*
Proterozoic, Late(?)*
Geologic Province:
Lake Superior region*
Wisconsin arch*
Sioux uplift*
Areal Extent:

Type Locality:
Exposures on Keweenaw Peninsula, northern MI (Brooks, 1876).

Bergland Group (MI*,WI*), Bessemer Quartzite (MI*,WI*), Jacobsville Sandstone (MI*), Oronto Group (MI*,MN*,WI*), Powder Mill Group (MI*,WI*), Bayfield Group (WI*), Chengwatana Volcanic Group (WI*,MN*), Beaver Bay Complex (MN), Duluth Complex (MN*), Fond Du Lac Formation (MN*), Hinckley Sandstone (MN*), Hovland Diabase Complex (MN), North Shore Volcanic Group (MN*), Puckwunge Formation (MN), Reservation River Diabase Complex (MN), Solor Church Formation (MN)

Unit Name History:
Named (Brooks, 1876). Revised (Grout and Schwartz, 1939; Stauffer and Thiel, 1941; Grout and others, 1951). Overview; subdivided in MI into Powder Mill Group (base), middle Keweenawan rocks, and Oronto Group (top) (Cannon, 1986). Not used (Morey and Van Schmus, 1988). Areal limits; Age modified (Cullers and Berendsen, 1993).

Note: If you need more information, please contact Nancy Stamm (
Asterisks (*) indicate usage by the U.S. Geological Survey. Other usages by state geological surveys.

"No current usage" implies that a name has been abandoned or that it has fallen into disuse. Former usage and, if known, replacement name given in parentheses ().

Slashes (/) indicate unit name usage violates the 1983 North American Stratigraphic Code. This violation may be explained within brackets ([ ]).

U.S. Department of the Interior, U.S. Geological Survey, Reston, VA, USA
Database project personnel
Last modified: 15-Jan-2013