Usage:
Slack Canyon member (informal) of Grande Ronde Basalt of Columbia River Basalt Group (OR*,WA*)
Slack Canyon member (informal) of Grande Ronde Basalt of /Yakima basalt subgroup [informal] of Columbia River Basalt Group (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 (middle Miocene)*
Type section, locality, area and/or origin of name:
Named from Slack Canyon, adjacent to Moses Coulee, [in secs. 2, 3, and 11, T. 23 N., R. 23 E., Alstown and Palisades 7.5-min quadrangles, Douglas Co., central WA] (see Reidel and others, 1989).
Reference locality: Douglas Creek-Slack Canyon, in sec. 11, T. 23 N., R. 23 E., Palisades 7.5-min quadrangle, [Douglas Co., central WA] (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 ([ ]).