Usage:
Foster Formation (MI-subsurface)
[?] Foster Formation of Prairie du Chien Group (MI-locally in subsurface)
Subunits:
Brazos shale (informal) at top.
Geologic age:
Early to early(?) Middle Ordovician (Ibexian to early? Whiterockian)
Type section, locality, area and/or origin of name:
Type section (subsurface): depth-interval 11,478 to 12,996 ft (3,498 to 3,961 m), Brazos-Sun-Superior State Foster No. 1 well, in sec. 28, T. 23 N., R. 2 E., Ogemaw Co., MI (Fisher and Barratt, 1985).
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 ([ ]).