Usage:
Chilson Member of Lakota Formation (MT*?, SD*,WY*)
(Use of name not recommended outside of Black Hills area, SD, WY.)
Geologic age:
Early Cretaceous*
Type section, locality, area and/or origin of name:
Type section: Chilson Canyon, in sec. 32, T. 8 S., R. 4 E., Flint Hill quadrangle, Fall River Co., SD. Named from Chilson Canyon, Fall River Co., SD (Post and Bell, 1961).
AAPG geologic province:
Chadron 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 ([ ]).