Usage:
Big Valley Formation of Three Forks Group (MT)
Big Valley Formation (MT)
Geologic age:
Late Devonian
Type section, locality, area and/or origin of name: (See Canadian Lexicon)
["Type section"] (subsurface): depth-interval 5,250 to 5,295 ft, Canadian Gulf Rumsey No. 6-30 well, LSD 6-30-33-21 West of 4th Meridian (W4M), Stettler area, Alberta, Canada (Wonfor and Andrichuk, 1956).
AAPG geologic province:
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 ([ ]).