Usage:
Tongue River Member of Fort Union Formation (MT*,ND*,SD*,WY*)
Subunits:
FORMATION STATUS (alphabetical) --all in ND: HT Butte Bed, Medora Member.
MEMBER STATUS: [†?]Almont Sandstone [unranked] (ND), Anderson coal bed (informal) (MT,WY), Beaver Creek lignite bed (informal) (ND*), Berg bed (informal) (ND*), HT Butte Lignite Bed (ND*).
Geologic age:
early Tertiary (late Paleocene; Tiffanian)*
Type section, locality, area and/or origin of name:
Named from exposures along Tongue River, northeastern WY and southeastern MT (Taff, 1909).
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 ([ ]).