Usage:
San Juan Tuff (CO*)
San Juan Formation (CO*)
San Juan Breccia (CO*)
Subunits:
(alphabetical): Canyon Creek Member (CO*), Sneffels Member (CO*).
Geologic age:
early Tertiary (Oligocene)*
Type section, locality, area and/or origin of name:
Notable exposures in Telluride district, [San Miguel, San Juan, and Ouray Cos., Telluride quadrangle], southwestern CO (Cross, 1896).
[Widely distributed in northwestern part of San Juan Mountains, in Telluride, Silverton, and Montrose quadrangles. Extends to north of Montrose and Uncompahgre quadrangles into West Elk Mountains (Gunnison National Forest).]
AAPG geologic province:
Paradox basin*
San Juan 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 ([ ]).