Usage:
Rierdon Formation of Ellis Group (MT*,ND*,WY*)
Rierdon Formation of Sundance Group (MT,WY)
Rierdon Limestone of Ellis Group (MT*)
Subunits:
(alphabetical) --all in WY: Canyon Springs Sandstone Member, Hulett Sandstone Member, Lak member.
Geologic age:
Jurassic, Middle*
Bathonian, late*
Callovian, early*
Type section, locality, area and/or origin of name:
Rierdon Gulch, in W/2 sec. 23, T. 24 N., R. 9 W., Teton Co., MT (Cobban, 1945).
AAPG geologic province:
Central Montana uplift*
Sweetgrass arch*
Williston basin*
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 ([ ]).