[Name "Petes Summit" used in diagram by Kay (1960)]. Petes Summit Formation listed as second from oldest formation (of 4) of Clipper Canyon Group. Consists of successive [informal] members of black argillite, quartz- and calc-arenite, lower orthoquartzite, quartz-silty and siliceous argillite, and upper orthoquartzite. Thickness is about 600 ft. Report includes list of graptolites and associated fossils of Arenigian, Llanvirnian and Llandeilian ages. [Based on 1983 DNAG Geologic Time scale, age is Early and Middle Ordovician].

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

Named from Petes Summit, pass between Petes Canyon and tributary of Sams Canyon on Wilson Ranch-Frontier Road, Toquima Range, Lander Co, NV. Is second from oldest formation in Clipper Canyon Group (new). Shown on map of Petes Summit Sheet, Nye and Lander Cos, NV. Consists of 5 informal members: argillite with limestone and sandstone interbeds (about 200 ft thick), siliceous argillite (about 200 ft), lower quartzite (25 ft), upper siliceous shale (150 ft), and upper quartzite (30 ft). Total is about 600 ft. Overlies Charcoal Canyon Formation; underlies Sam Spring Formation (both new and of Clipper Canyon Group). Locally unconformably underlies Tertiary sedimentary and volcanic rocks. Age is Early and Middle Ordovician based on graptolites ranging in age from Arenigian to Llandeilian.

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