Usage:
Twisp Formation of Newby Group (WA)
Geologic age:
Jurassic, Early(?)
Jurassic, Middle(?)
Type section, locality, area and/or origin of name:
Type area: exposures in the channel walls of the Methow and lower Chewack Rivers, between Twisp and a point 2 mi north of Winthrop [in T. 35 N., R. 21 E., Lewis Butte 7.5-min quadrangle] Okanogan Co., WA (Barksdale, 1975).
AAPG geologic province:
Northern Cascade Range-Okanagan province
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 ([ ]).