Abstract

The Confusion Range, in west-central Utah between the House Range on the east and the Snake Range of Nevada on the west, is a folded mountain range which has been maturely dissected into hogbacks, strike valleys, and a few larger anticlinal valleys and synclinal ridges. At lower elevations are pediments, fans, and shore lines of Lake Bonneville.

The stratigraphic section includes an estimated 17,000 to 23,000 feet of sedimentary strata ranging from Ordovician to Lower Triassic. The pre-Mississippian includes approximately 800 feet of lower dolomitic limestones, 300 feet of white quartzite probably equivalent to the Eureka of eastern Nevada, and an upper 3000 feet or more of dolomitic limestones. The Mississippian, 1825 feet thick, is a limestone section with a fauna strikingly comparable to that of the typical Mississippi Valley section. Near the base an upper Kinderhook zone carries abundant crinoids, and higher zones correspond to the Burlington, Keokuk, Moorefield, and Chester. The Pennsylvanian limestones, 1600 feet thick, also contain a midwestern fauna. The Permian, 8500 feet thick, is divided into a lower, sandy, and essentially nonfossiliferous facies, and an upper limestone facies carrying the Punctospirifer pulcher fauna typical of the Great Basin. The Lower Triassic, nine hundred feet thick, is dominantly shaly with thin limestone beds at intervals. It carries a prominent ammonite fauna. The youngest rocks in the area are small patches of Tertiary rhyolitic (?) and basaltic extrusives.

The range suffered strong eastward compression during the Cretaceous (?) or early Eocene (?). The axes of major folds are prominently arcuate, with probably some overthrusting and transverse tear faulting in the area of greatest axial curvature. No evidence of block faulting was observed.

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