Usage:
Mackinaw facies (informal) in Henry Formation of Mason Group (IL*)
(†Mackinaw Member abandoned as formal term by the IL Geol. Survey.)
Informal. The rank or lithologic term should not be capitalized.
Geologic age:
Pleistocene (Wisconsinan Age)*
Type section, locality, area and/or origin of name:
Type section: gravel pit on southwest side of Mackinaw, in NE/4 NW/4 sec. 19, T. 24 N., R. 2 W., Tazewell Co., central IL. Named from village of Mackinaw, Tazewell Co., central IL (Willman and Frye, 1970).
AAPG geologic province:
Illinois 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 ([ ]).