Stratigraphy and structure of the San Rafael Reef, Utah; A major monocline of the Colorado Plateau

Abstract Location. The San Rafael Swell is a major domal uplift in the northwestern Colorado Plateau and dominates the structure of east-central Utah. The San Rafael Reef site is on its eastern edge, approximately 13 mi (21 km) west of Green River, in Emery County, Utah (Fig. 1). 1–70 cuts more or less directly across the structure (Rigby and others, 1974). Accessibility. Roadcuts are on right-of-way controlled by the Utah State Highway Commission. Land along side the route is generally controlled by the U.S. Bureau of Land Management.Alluvial flats along the San Rafael River are on private land. Significance of Site. The San Rafael Swell is characteristic of many asymmetric large uplifts of the Colorado Plateau; and itseastern margin, the San Rafael Reef, is representative of monocline of the province. A complete stratigraphic sequence from the Permian White Rim-Cedar Mesa Sandstone up through Triassicand Jurassic rocks to the lower part of the Cretaceus Mancos Shale Fig. 2 is exposed along the highway. These rocks accumulated in a wide variety of depositional enviroments, ranging from marine carbonate and elastic environments to deserts(Rigby, 1978).