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National Geologic Map Database

Geologic Unit: Chilson

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 does not conform with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005). This may be explained within brackets ([ ]).