Usage:
Three Sisters Formation (ID*,WA*)
Geologic age:
Neoproterozoic*
Type section, locality, area and/or origin of name: (See Canadian Lexicon)
Type locality not designated (British Columbia).
Principal reference locality: Slopes of the Three Sisters Peaks (Salmo 82 F/3 E 1:50,000 quadrangle) British Columbia, Canada (Miller, 1994).
AAPG geologic province:
Northern Cascade Range-Okanagan province*
Idaho Mountains 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 ([ ]).