Named as one of six formations of Copper Basin Group (rank revised) for Brockie Lake. Type section measured from NE1/4 SW1/4 NE1/4 sec 8, T4N, R22E to center W1/2 sec 9, T4N, R22E, Custer Co, ID in the Idaho Mountains province. Overlies Muldoon Canyon Formation (new) of Copper Basin; contact is placed at first occurrence of gray cobble conglomerate or gray quartzite. Gradationally underlies Iron Bog Creek Formation (new), upper formation of Copper Basin; contact placed where dark argillite and thin-bedded quartzite predominate over conglomerate and thick-bedded quartzite; upper contact gradational over 800 ft. Unit was placed in Copper Basin and in Wood River Formations in some earlier published reports. Is exposed along north edge of Snake River plain as far north as T8N, R20E. Is 2,150 ft thick at type. Consists of: 1) conglomerate (85 percent) of granules, pebbles or cobbles of mostly white to gray quartzite and some nonresistant mudstone and chert clasts in a silica matrix of coarse to medium grain quartz, chert, and other rock fragments; 2) light-gray, fine- to medium-grained, moderately well-rounded quartzite; 3) thin-bedded argillite (5 percent). Unidentifiable pelecypod fragments. Assigned to Early? and Middle? Pennsylvanian on basis of stratigraphic relationship to other units. Nomenclature chart.

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

Is one of six formations assigned to the Copper Basin Group. Lies above Muldoon Canyon Formation of Copper Basin. Underlies Iron Bog Creek Formation, upper formation of Copper Basin. Age assignment modified in Pioneer Mountains, ID in the Idaho Mountains province, from Early? and Middle? Pennsylvanian to Late Mississippian [specific evidence not given].

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

Rank reduced and assigned as one of four members of newly named Argosy Creek Formation of Copper Basin Group (revised). Argosy Creek includes all units within Copper Basin Group above Drummond Mine Limestone: Scorpion Mountain, Muldoon Canyon, Brockie Lake Conglomerate, and Iron Bog Creek Members, all reduced from formation rank. Argosy Creek defined because upper part of Copper Basin Group is poorly exposed and abrupt facies changes make previous formation-rank units difficult to map. Occurs in area of Pioneer Mountains, Blaine Co, ID (Snake River basin) west of Copper Basin thrust fault. Consists of pebble to boulder conglomerate with minor interbeds of sandstone and argillite. Contains ichnofossils PHYCOSIPHON. Measured section; geologic map (fig 4); correlation charts. Overlies with angular disconformity Muldoon Canyon Member; disconformity thought to span much of Osagean time. Underlies with gradational contact Iron Bog Creek Member. Assigned Late Mississippian (Meramecian) age.

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