Green River Formation at Raven Ridge, Uintah County, Utah

Along Raven Ridge in Uintah County, Utah, exposures of the Green River Formation contain a complex sequence of intertonguing beds of sandstone, shale, limestone, and marlstone. These strata are considered to represent deposition in an orderly sequence of environments from the flood plain through the lake margin and stream deltas into the quiet waters offshore. The area is a model for the study of facies sequences that are less readily apparent in the subsurface. The importance of these facies to the economic entrapment of oil is reflected in the many oil-saturated and stained sandstone beds in the outcrop. The position of these oil-bearing strata bears a strong relationship to paleoenvironments along the margin of Lake Uintah. A geologic map along the Utah portion of Raven Ridge shows the distribution of eight informal mappable units. Since most of these units are lithofacies, the mapping illustrates lateral relationship. Lithologic descriptions and environmental interpretations of each of these units are given.