Usage:
Swift Formation of Ellis Group (MT*,ND*,WY)
Swift Sandstone of Ellis Group (MT*)
Swift Formation of Sundance Group (MT,WY)
Geologic age:
Jurassic, Late*
Divesian, late*
Argovian*
Oxfordian*
Type section, locality, area and/or origin of name:
Swift Reservoir on Birch Creek, in NE/4 sec. 27, T. 28 N., R. 10 W., Pondera Co., MT. Named from Swift Reservoir (Cobban, 1945).
AAPG geologic province:
Sweetgrass arch*
Montana folded belt*
Central Montana uplift*
Williston basin*
Powder River basin*
Bighorn basin*
Chadron arch
Wind River 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 ([ ]).