Usage:
Chisos Group (TX-local)
Recognized in southwestern TX, notably Trans-Pecos area, Big Bend National Park, and Big Bend Ranch State Park.
Subunits:
(alphabetical) --all in TX: Alamo Creek Basalt, [?] Ash Spring Basalt or [?] Ash Spring Basalt Member, Bee Mountain Basalt, Mule Ear Spring Tuff, Tule Mountain Trachyandesite.
Geologic age:
early Tertiary (Eocene to Oligocene)
Type section, locality, area and/or origin of name:
Named from Chisos Mountains, Brewster Co., western TX (US geologic names lexicons, USGS Bull. 896, 1200).
Principal occurrence at Fresno Mine, in Terlingua district, Brewster Co., TX (Yates and Thompson, 1959).
AAPG geologic province:
Permian 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 ([ ]).