Usage:
Siwash Formation (WA)
Geologic age:
Tertiary
Type section, locality, area and/or origin of name:
Duffy's Mountain measured section, on east side of Okanogan River north of Tonasket, in NW/4 sec. 2, T. 37 N., R. 27 E., Okanogan Co., WA (Marjaniemi and Robins, 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 ([ ]).