Usage:
Flood Member of Blackleaf Formation of Colorado Group (MT*)
Geologic age:
late Early Cretaceous (Albian)*
Type section, locality, area and/or origin of name:
Type section: on south side of Sun River valley, 4.5 mi west of Great Falls, in SW/4 NW/4 NE/4 sec. 7, T. 20 N., R. 3 E., Cascade Co., MT. Named from exposures along bluffs on west side of Missouri River near Flood Siding on the Great Northern Railway, in NW/4 sec. 34, T. 20 N., R. 3 E., Cascade Co., MT (Cobban and others, 1959).
AAPG geologic province:
Sweetgrass arch*
Montana folded belt*
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 ([ ]).