Usage:
St. David Formation (AZ-recognized locally in San Pedro Valley)
Geologic age:
late Tertiary to Quaternary (Pliocene to Pleistocene; Blancan to Irvingtonian NALMA)
Due to change in Plio-Pleistocene boundary, age may now be considered all or in part Pleistocene.
Type section, locality, area and/or origin of name:
Type locality: in badlands topography along east and west sides of San Pedro Valley near St. David and Benson, [Saint David and Benson 7.5-min quadrangles], Cochise Co., southeastern AZ (Gray, 1967).
Type section: includes section CR-1 through section CR-4, exposed in secs. 24 through 27, T. 18 S., R. 21 E., [Land 7.5-min quadrangle], Cochise Co., southeastern AZ (Gray, 1967).
Supplemental sections: section PR-1 through PR-3 located in secs. 27 and 28, T. 17 S., R. 20 E., [Benson 7.5-min quadrangle], Cochise Co., southeastern AZ (Gray, 1967).
AAPG geologic province:
Pedregosa 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 ([ ]).