Geologic Unit: Missoula

Usage:

Missoula Group of Belt Supergroup (ID*,MT*,WA*)

Subunits:

(alphabetical): Bonner Formation (ID*,MT*,WA?) or Bonner Quartzite (MT*), Garnet Range Formation (MT*) or Garnet Range Quartzite (MT*), Gateway Formation (MT), Greyson Formation (MT*) or Greyson Shale (MT*), Libby Formation (ID*,MT*,WA*), Marsh Formation (MT), McNamara Formation (MT*) or McNamara Argillite (MT*), Miller Peak Formation (MT*), Mount Shields Formation (ID*,MT*), Phillips Formation (MT), Pilcher Quartzite (MT*) or Pilcher Formation (MT*), Purcell Lava (MT*) or Purcell Basalt (MT*), Rock Rabbit Formation (MT), Roosville Formation (MT), Sheep Mountain Quartzite (MT), Shepard Formation (ID*,MT*), Snowslip Formation (ID*,MT*), Striped Peak Formation (ID*,MT*,WA*).

Geologic age:

Mesoproterozoic*

Type section, locality, area and/or origin of name:

Notable exposures in mountains east of city of Missoula, Missoula Co., western MT (Clapp and Deiss, 1931).
Type locality: slopes east and west of Rattlesnake Creek, northeast of Missoula, [Bonner quadrangle (scale 1:125,000), Powell Co., in Lolo National Forest], western MT (Fenton and Fenton, 1937).
Reference section: along crest of ridge parallel to and northwest of Camp Creek, in unsurveyed secs. 22, 28, and 33, T. 20 N., R. 12 W., Ovando quadrangle [Trap Mountain and Pilot Peak 7.5-min quadrangles], Powell Co., central western MT (McGill and Sommers, 1967).

AAPG geologic province:

Northern Rocky Mountain region*