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This 1:62,500-scale digital dataset represents geologic features that cover the Hite Crossing-lower Dirty Devil River area and is one of several maps recently produced by the Utah Geological Survey that together provide complete printed and Geographic Information System (GIS) geologic map coverage of Glen Canyon National Recreation Area. The map area includes the confluence and deep canyons of the Colorado and Dirty Devil Rivers, which are crossed by State Highway 95, completed in 1966 and later designated as Utah's Bicentennial Highway. Exposed strata range from the Pennsylvanian Honaker Trail Formation to the Jurassic Carmel Formation, but deep reddish-brown, orangish-red, and tan Permian to Jurassic strata that create popular colorful scenery near Lake Powell dominate the area. Overall, strata dip gently to the west and are cut by a swarm of mostly northwest-trending faults, most with offsets of a few feet to a few tens of feet. Surficial deposits include broad areas of eolian sand, alluvial fans, river and stream terrace gravels, and several large landslides in the Chinle and overlying formations. During high water levels, Lake Powell extends far up the canyons of both rivers, but when the lake is down about 30 meters (100 feet) or more it does not extend into the map area and the rivers incise into large deltaic mudflats. |