Named as middle formation of Oquirrh Group (rank raised) for Butterfield Peaks in Tooele Co, UT in Great Basin province. Is part of Bingham sequence. Type section designated and measured in secs 6, 7, 18, 19, 20 and 21, T4S, R3W and sec 12, T4S, R4W, Fairfield, Stockton, and Bingham Canyon quads. Reference section for lower part designated and measured in secs 26, 27, and 34, T4S, R4W, Stockton quad. These rocks were formerly assigned to upper Maple Formation, and all of "White Pine" and Butterfield Formations. Is predominantly brown-gray, fine- to medium-grained, medium to massive bedded, calcareous quartzite which locally may contain argillaceous limestone laminations; silica-cemented brown-gray orthoquartzite; arenaceous, cherty, argillaceous; and dark gray, fine crystalline to medium sandy, thin to medium bedded, dense limestone. Quartzite is cross-bedded and ripple marked on bedding surfaces. Thin black chert nodules and lenses locally band the rocks. Is 9,072 ft thick at type; 3,863 ft measured at partial reference section. Rests conformably on West Canyon Limestone (new) of Oquirrh. Conformably underlies Clipper Ridge Member (new) of Bingham Mine Formation (new) of Oquirrh. Contains abundant fauna (listed) of brachiopods, corals, bryozoans, and fusulinids. Assigned to the Middle Pennsylvanian, Des Moines. Lower few hundred ft may be Atoka. Columnar sections. Correlation chart.

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

Oquirrh Group in report area Great Basin province divided into the West Canyon Limestone, Butterfield Peaks Formation, and Bingham Mine Formation. Conodonts (listed) in the West Canyon suggestive of Morrowan age. Fusulinids (listed) in the Butterfield Peaks are Atokan and Desmoinesian. The oldest fusulinids in this study are from Butterfield Peaks "equivalents" and are latest Atokan to early Des Moinesian age. Late Des Moinesian fusulinids --MILLERELLA sp, WEDEKINDELLA spp, and BEEDEINA spp --identified in upper part of Butterfield Peaks. Fusulinid fauna in the Bingham Mine is more restricted here than in the Bingham Mining district; TRITICITES were collected from near the base was of Mississippian age and a younger Virgilian age TRITICITES also found but site of find within formation not stated. The three formations mapped (geologic map).

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