Usage:
Orman Lake Limestone Member of Greenhorn Formation (MT*,SD*,WY*)
Geologic age:
early Late Cretaceous (Cenomanian)*
Type section, locality, area and/or origin of name:
Not designated. Named from "very good" exposures on the west and south sides of Orman Lake, and in the peninsula that extends into the lake from the southeast, in southwest Butte Co., SD (Petsch, 1949).
AAPG geologic province:
Powder River basin*
Williston 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 ([ ]).