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National Geologic Map Database

Geologic Unit: Inyan Kara

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