Usage:
Challis Volcanic Group (ID*,MT*)
Challis Volcanics (ID*,MT*)
[Challis Volcanic Group adopted by the ID and MT Geol. Surveys, and the USGS (rules suspended).]
Subunits:
GROUP STATUS (alphabetical) --all in ID: Cheney Volcanics, Kadletz Volcanics, [†?]Kenney Formation, Yearian Volcanics.
Geologic age:
Tertiary*
Eocene*
Type section, locality, area and/or origin of name:
Not designated. Named from Challis National Forest and town of Challis, Custer Co., ID (Ross, 1930).
Named from town of Challis, Custer Co., ID (Ross, 1934).
[A group name combines a geographic name with the term "group," and no lithic designation is included (ACSN, 1961, 1970; NACSN, 1983, 2005).] (Rules suspended. Mapped along ID-MT State Line by ID and MT Geol. Surveys, Natl Coop Geol Map Prog STATEMAP, and used by USGS geologists, June-July 2018).
AAPG geologic province:
Central Western Overthrust*
Idaho Mountains province*
Snake River 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 ([ ]).