Abstract

Rocks in the north end of the Oquirrh Mountains, Utah, belong mostly to the Oquirrh formation, which rests conformably on the Manning Canyon(?) shale, the oldest unit exposed. Remnants of Tertiary and early Quarternary coarse clastic rocks lie unconformably on the Paleozoic rocks, and Tertiary andesite overlies Tertiary conglomerate. Unconsolidated deposits of Pleistocene and Recent age include undifferentiated alluvial, colluvial, fanglomerate, and lake deposits.

The Manning Canyon (?) shale consists of thin shale and shaly limestone beds. In its type area the Manning Canyon shale is of Mississippian and Pennsylvanian age. The overlying Oquirrh formation, which is of Pennsylvanian and Permian age elsewhere in the region, contains in this area a Mississippian fauna in the lowermost beds. The Oquirrh formation is divided into seven mappable units: unit 1, at the base, consists of limestone and subordinate interlayered shale and sandy limestone 2,750 feet thick; unit 2 is irregularly repeated thin sequences of sandy limestone, quartzite, shale, and limestone 600 feet thick; unit 3 is repetitive thick sequences of limestone, quartzite, and shale 1,700 feet thick; unit 4 is dominantly thick-bedded cherty limestone with less abundant thick-bedded quartzite 1,300 feet thick; unit 5 is thick-bedded quartzite and subordinate cherty limestone 750 feet thick; unit 6 is massive quartzite and sandstone with interlayered thin limestone, dolomite, and shale beds about 3,000 feet thick; unit 7, the uppermost unit, is inter-bedded limestone, dolomite, quartzite, sandstone, and shale at least 1,500 feet thick.

The uppermost beds of the Oquirrh are unconformably overlain by unnamed conglomerate as much as 100 feet thick of Tertiary age, and by the Harkers fanglomerate of Slentz (1955, p. 28) of Tertiary age and coarse clastics of Quaternary age that have a maximum thickness of 300 feet.