Usage:
Polk Creek Shale (AR*,OK*,TX*)
Polk Creek Formation (AR*)
Geologic age:
Late Ordovician (Cincinnatian; Maysvillian to Gamachian)*
Type section, locality, area and/or origin of name:
Named from Polk Creek, Caddo Gap quadrangle, Montgomery Co., southwestern AR (US geologic names lexicons, USGS Bull. 896, 1200; McFarland, 2004).
AAPG geologic province:
Ouachita folded belt*
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 ([ ]).