Usage:
Ludlow Member of Fort Union Formation (MT*,ND*,SD*)
Ludlow Formation of Fort Union Group (ND,SD)
Geologic age:
early Tertiary (Paleocene)*
Type section, locality, area and/or origin of name:
Type locality: vicinity of Ludlow, Harding Co., southwestern SD (Lloyd and Hares, 1915).
AAPG geologic province:
Williston 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 ([ ]).