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National Geologic Map Database

Geologic Unit: McMillan

Usage:

No current usage.
(†McMillan Formation (OH*) considered obsolete. Is same as Grant Lake Formation. See Grant Lake.)


Geologic age:

Late Ordovician (Cincinnatian; Maysvillian)


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

Cincinnati, OH. Named from McMillan Street (Bassler, 1906).


AAPG geologic province:

Cincinnati 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 does not conform with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005). This may be explained within brackets ([ ]).