Spokane Formation of Ravalli Group of Belt Supergroup (MT*)
(Restricted from Glacier National Park and adjacent areas, Glacier Co., MT, where Grinnell is exposed.)
Prickly Pear Member (MT).
Middle Proterozoic*
Type locality: in Spokane Hills, 15 mi east of Helena, Lewis and Clark Co., western central MT (Walcott, 1899).
Northern Rocky Mountain region*
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
Asterisk (*) indicates published by U.S. Geological Survey authors.
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