Usage:
Inyan Kara Group (MT*,SD*,WY*)
Inyan Kara Formation (ND)
Subunits:
GROUP STATUS (alphabetical): Fall River Formation (MT,SD*,WY*) or Fall River Sandstone (SD*), Fuson Formation (MT,SD*,WY*) or Fuson Shale (SD*,WY*), Lakota Formation (SD*,WY*) or Lakota Sandstone (SD*,WY*).
Geologic age:
Early Cretaceous*
Type section, locality, area and/or origin of name:
Not designated. Origin of name not stated by author, but probably named from Inyan Kara Creek, west side of Black Hills, Crook Co., WY (Rubey, 1930).
AAPG geologic province:
Powder River basin*
Chadron arch*
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 ([ ]).