Pg. 6, 8-15, pl. 1. Auts Canyon formation of Sheeprock group. Succession of phyllites, phyllitic quartzites, quartzites, feldspathic quartzites, and graywacke conglomerate semischists that comprises allochthon of Sheeprock thrust. Total measured thickness 5,559 feet. Underlies Ekker formation (new). Age is Precambrian.
Named from Aut's [Otts] Canyon, [in T. 10 and 11 S., R. 5 and 6 W.], Dutch Peak area, Sheeprock Range, [Dutch Peak 7.5-min quadrangle], Juab and Tooele Cos., west-central UT.

Source: US geologic names lexicon (USGS Bull. 1200, p. 175); supplemental information from GNU records (USGS DDS-6; Denver GNULEX).

Spelling emended from Auts Canyon to Otts Canyon to conform with spelling of canyon name on Dutch Peak topographic quadrangle map. In the Sheeprock Mountains of north-central Utah (Great Basin region), Otts Canyon Formation is assigned to Sheeprock Group (rank raised) as its basal formation. Replaces "lower Sheeprock" of Cohenour (1959). Divided into three unnamed members. Lower member, a gray to black slate and phyllite with subordinate quartzite and grit, at least 700 m thick; metamorphosed to hornfels between Otts Canyon and west flank of range. Middle member, an interbedded diamictite, quartzite, graywacke, grit, and slate, 0 to 500 m thick; varies in color from gray, green, to black. Upper member, a gray quartzite with subordinate interbeds of conglomerate, grit, graywacke, slate, siltstone, and shale, 200 to 1,000 m thick. Diabase sills up to 150 m thick present at or near top of upper member; diabase is massive, non-vesicular and probably intrusive. Underlies Dutch Peak Formation (formerly Dutch Peak Tillite) of Sheeprock. Age is Late Proterozoic. Report includes geologic map, stratigraphic charts.

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