Usage:
Amasa Formation of Menominee Group of Marquette Range Supergroup (MI*-local)
Amasa Formation of Baraga Group of Marquette Range Supergroup (MI-local)
Notable exposures in Iron River-Crystal Falls district, Northern Peninsula.
Geologic age:
Paleoproterozoic*
Type section, locality, area and/or origin of name:
[Type area]: on western Menominee Range, in Iron Co., Northern Peninsula, northwestern MI (Royce, 1936).
AAPG geologic province:
Lake Superior region*
Michigan basin*
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 ([ ]).