First published use as the upper member of the Grinnell formation of Ravalli group of Belt series. Intent to name not stated. No type locality designated nor source of geographic name stated. Is 425 to 750 ft thick in a generalized section compiled from information on rocks south of Ahern Pass in Lewis Range and in Boulder Pass, Clark Range, Glacier National Park, MT in the Northern Rocky Mountain region, and Waterton Lakes Park, AT and BC, CN. [Not possible to determine exact areal extent.] Composed of red to green argillite in beds 1-3 ft thick that are interbedded with red, gray, white and green quartzite and conglomerate. Argillite balls abundant in quartzite layers. Mud cracks and coarse current ripple marks common. Some rain prints. More quartzite at top. Well exposed over Gunsight Pass and on mountains bordering Swift Current Valley. Overlies Red Gap member (first used) of Grinnell. Underlies COLLENIA SYMMETRICA zone of Siyeh formation. Of Algonkian, Proterozoic age.

Source: GNU records (USGS DDS-6; Denver GNULEX).

Is the upper member of the Grinnell formation of Ravalli group of Belt series. Type locality [none designated in first publication on Rising Bull] stated to be in upper cliffs of Mt. Rockwell (Rising Bull of the Blackfeet), south of Two Medicine Lake, Glacier National Park, MT in the Northern Rocky Mountain region. Consists of an upper and lower, white, gray, green, and red, cross-bedded quartzite that are interbedded red argillite separated by a middle unit of dark-red argillite and interbedded white gray, or pink quartzite in a section at Cut Bank Pass where 395 ft were measured. Ranges from 600 to 1,100 ft. Has coarse, abundant mudcracks. Overlies Rising Wolf member of Grinnell. Underlies Siyeh formation of Piegan group (new). Correlation chart. Of pre-Cambrian age.

Source: GNU records (USGS DDS-6; Denver GNULEX).