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National Geologic Map Database

Geologic Unit: Four Mile Dam

Usage:

Four Mile Dam Formation of Traverse Group (MI*)


Subunits:

Dock Street Clay Member (MI).


Geologic age:

Middle Devonian*


Type section, locality, area and/or origin of name:

Type section: at Four Mile Dam on Thunder Bay River, Alpena Co., northeastern MI (Cooper and Warthin, 1941).


AAPG geologic province:

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 ([ ]).