Geology of the Cottonwood Creek Coal Quadrangle, Grand County, Utah

The Cottonwood Creek Coal Quadrangle is located in the Book Cliffs, a major escarpment in eastern Utah. Strata of these cliffs dip in a northerly direction into the Uintah Basin. The shape of this sinuous escarpment is strongly influenced by two major structural features that lie to the south, the San Rafael Swell to the west and the Uncompahgre Uplift to the east. The portion of the Book Cliffs that lies within the boundaries of the thesis area contains formations that are late Cretaceous and early Tertiary in age. The Cretaceous units, in ascending order, include the Mancos Shale and the Price River formation containing the Castlegate Sandstone, Buck Tongue of the Mancos Shale, Sego, Neslen and Farrer Members. Above the Farrer lies the Tuscher Formation in which the Cretaceous-Tertiary boundary is likely contained. The uppermost unit is the Wasatch Formation which is Paleocene to Eocene in age. Three major sedimentary facies are present within the quadrangle. Marine facies are found in the middle to lower portions of the Buck Tongue and the main body of the Mancos Shale. The upper portions of these units, along with the Castlegate Sandstone, Sego, and the lower part of the Neslen Members are comprised of various deltaic facies. Above these units, the rocks are continental in origin