Usage:
Thirtyone Formation (TX-subsurface)
Geologic age:
Devonian, Early
Devonian, Middle
Type section, locality, area and/or origin of name:
Type section (subsurface): depth-interval 8,040 to 9,050 ft, Champlin Refining Company No. 1 Crane-University well, in sec. 40, Blk. 31, University Lands Survey, Crane Co., TX (Hills and Hoenig, 1979).
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 ([ ]).