Usage:
Lak Member of Sundance Formation (CO*,MT?,SD*,WY*)
Lak Member of Rierdon Formation of Sundance Group (WY)
Geologic age:
late Middle Jurassic (Callovian)*
Type section, locality, area and/or origin of name:
Type section: on west side of Stockade Beaver Creek, about 5 mi northeast of Newcastle, WY, and 3 mi north of Lak Reservoir, in sec. 18, T. 45 N., R. 60 W., Weston Co., WY. Named from Lak Reservoir on L.A.K. Ranch (Imlay, 1947).
AAPG geologic province:
Denver basin*
Powder River basin*
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 ([ ]).