Usage:
Ravalli Group of Belt Supergroup (ID*,MT*,WA*)
Ravalli Formation of Belt Supergroup (ID,WA)
Ravalli Argillite of Belt Supergroup (ID*,MT*,WA*)
Subunits:
GROUP STATUS (alphabetical): Appekunny Formation (MT*), Burke Formation (ID*,MT*,WA*), Empire Formation (MT*), Grinnell Formation (MT*), Revett Formation (ID*,MT*,WA*), Spokane Formation (MT*) or Spokane Shale (MT*), St. Regis Formation (ID*,MT*,WA*).
Geologic age:
Mesoproterozoic*
Type section, locality, area and/or origin of name:
Not designated. Origin of name not stated by author, but probably named from occurences near the town of Ravalli, ID (Walcott, 1906).
AAPG geologic province:
Northern Rocky Mountain region*
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 ([ ]).