Usage:
Sunlight Group of Absaroka Volcanic Supergroup (MT*,WY*)
Subunits:
(alphabetical): Crescent Hill Basalt (WY*), Mount Wallace Formation (MT*,WY*), †Pitchfork Formation (WY), Trout Peak Trachyandesite (WY*), Wapiti Formation (MT*,WY*).
Geologic age:
early Tertiary (Eocene)*
Type section, locality, area and/or origin of name:
Type area: Sunlight Creek (Smedes and Prostka, 1972).
AAPG geologic province:
Bighorn basin*
Montana folded belt*
Yellowstone province*
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 ([ ]).