Pg. 26. Bridger Peak Quartzite of Libby Creek Group. White to tan, slabby to massive, cross-bedded, phyllitic, feldspathic, and pure orthoquartzite; interbedded, in lower 1,000 m, with biotite-chlorite schist, conglomeratic quartzite, and phyllite. Thickness <2,600 m. Conformably overlies Cow Creek Conglomerate; conformably underlies Copper Creek Conglomerate; lower unit (1000 m) lithologically similar to Heart Formation (Libby Creek Group) in Medicine Bow Range. Age is Early Proterozoic.
Type area: exposures in cirques in area of Bridger Peak, in T. 14 N., R. 86 W., Sierra Madre Range, Carbon Co., Medicine Bow National Forest, south-central WY.

Source: US geologic names lexicon (USGS Bull. 1520, p. 21).

Reassigned in the Sierra Madre from Libby Creek Group of Proterozoic age to Phantom Lake Metamorphic Suite of Late Archean age as its uppermost formation (of 3 formations). Unconformably overlies Silver Lake Metavolcanics (named) of Phantom Lake. Unconformably overlain by Proterozoic Snowy Pass Group (new). Bridger Peak as used in this paper agrees with Divis' use only in Bridger Peak area. Reasons for association with Phantom Lake rather than Libby Creek are: 1) position unconformably below Snowy Pass; and 2) correlation with Conical Peak Quartzite, upper formation of Phantom Lake Suite in Medicine Bow Mountains. Is about 800 m thick. Type locality designated as the Bridger Peak area, T14N, R86W, Carbon Co, WY, Northern Rocky Mountain region. Is well exposed at Vulcan Mountain and for several mi east of Bridger Peak and Vulcan Mountain. Quartzites vary from quartz arenite to argillaceous and arkosic quartzite. A quartz-pebble conglomerate with as much as 20 percent pyrite present on Vulcan Mountain. Has a few medium- to large-scale planar crossbeds and small-scale trough crossbeds. Transport dominant to the northwest. Depositional environment not well known. Basal part is of fluvial origin; genesis of rest of formation uncertain. Stratigraphic chart. Petrographic data. Geologic map. Of Late Archean age. Intruded by felsic igneous rocks thought to be equivalent to the 2,700 Ma Spring Lake Granodiorite.

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