Usage:
Willow Creek Formation (MT*)
Geologic age:
Late Cretaceous to early Tertiary (Maastrichtian to Paleocene)*
Type section, locality, area and/or origin of name: (See Canadian Lexicon)
Not designated. First recognized at the mouth of Willow Creek and on the neighboring part of the Oldman River in southwestern Alberta, Canada (Dawson, 1883).
AAPG geologic province:
Montana folded belt*
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 ([ ]).