Clastic laramide sediments of the Wasatch Hinterland, Northeastern Utah (Thesis and maps)

Four phases of the Laramide Orogeny are mirrored in the molasse-type sediments of the Wasatch Hinterland (Eardley, 1952, p. 52). The present nomenclature for these sediments is, from oldest to youngest: the Echo Canyon Conglomerate, Evanston Formation, and Wasatch Formation. Several tools useful in separating these formations are: (1) lithologic characteristics, (2) pebble counts, (3) paleocurrent studies, (4) radiometric dating of volcanic rocks, (5) facies relationships, (6) sedimentary expressions of Laramide tectonic phases, (7) subsidence basins, and (8) correlation of the sediments with similar units outside the Wasatch Hinter land. The Echo Canyon Conglomerate was deposited from west to east in the center of the Hinterland. The Evanston Formation consists of a lower conglomerate and an upper sandstone-siltstone unit. In the Salt Lake City Salient, the City Creek Canyon volcanics (tentative name) which overlie the Evanston Formation were found to be early Eocene (50 and 55 m. y.) by radiometric dating. This date gives a maximum age for the portion of the Wasatch Formation represented in the Salient where it unconformably overlies the volcanics. The early Eocene Wasatch Formation was deposited from west to east during a later phase of the Laramide Orogeny, but because of its large lateral extent it is divided into two facies; a western conglomerate facies and an eastern sandstone-mudstone facies.