No current usage.
(†Blackfoot Formation (MT*) abandoned.)
Mesoproterozoic*
Named from exposures in canyon of North Fork of Blackfoot River, central western MT, where entire section is exposed (US geologic names lexicons, USGS Bull. 896, 1200).
Northern Rocky Mountain region*
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 ([ ]).