Usage:
Arrow Creek Member of Colorado Shale (MT*)
Geologic age:
late Early Cretaceous (Albian)*
Type section, locality, area and/or origin of name:
Type section: on north side of Arrow Creek, in sec. 23, T. 18 N., R. 10 E., 4.5 mi northeast of Geyser, Judith Basin Co., MT (Reeside and Cobban, 1960).
AAPG geologic province:
Central Montana uplift*
Sweetgrass arch*
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 ([ ]).