Usage:
Wapshilla Ridge member (informal) of Grande Ronde Basalt of Columbia River Basalt Group (ID*,OR*,WA*)
Wapshilla Ridge member (informal) of Grande Ronde Basalt of /Yakima basalt subgroup [informal] of Columbia River Basalt Group (ID*,OR*,WA*)
Informal. The rank or lithologic term should not be capitalized. [Yakima basalt subgroup considered informal and should not be capitalized. "Subgroup" not recognized as a formal stratigraphic rank term (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). Columbia River Basalt Group adopted by the ID, OR, and WA Geol. Surveys, and the USGS (rules suspended).]
Geologic age:
late Tertiary (early Miocene)*
Type section, locality, area and/or origin of name:
Named from excelllent exposures on Wapshilla Ridge, which forms the divide btw. Snake and Salmon Rivers, Nez Perce Co., ID.
Reference localities: (1) Wapshilla Ridge, near confluence of Snake and Salmon Rivers, in secs. 2, 3, 11, and 12, T. 30 N., R. 4 W., Wapshilla Creek 7.5-min quadrangle, [Nez Perce Co.], ID; (2) Grande Ronde Basalt type locality, prominent west-trending spur ridge, extending from NW/4 sec. 23 across N/3 sec. 22 to NE/4 sec. 21, T. 7 N., R. 46 E., Black Butte quadrangle, in the lower part of Grande Ronde River Valley, Asotin Co., extreme southeast WA; and (3) Multnomah Falls, in sec. 18, T. 1 N., R. 6 E., Multnomah Falls 7.5-min quadrangle, [Multnomah Co., northern OR] (Reidel and others, 1989).
AAPG geologic province:
Eastern Columbia 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 ([ ]).