Abstract

A new geologic map of the Deer Point 7.5' quadrangle located in the southern region of Capitol Reef National Park in south-central Utah provides stratigraphic and structural detail not previously available. The Deer Point quadrangle was mapped at a scale of 1:24,000 and is the fourth geologic map completed at this scale in Capitol Reef National Park. Twelve Quaternary units and eighteen bedrock formations and members are exposed in the Deer Point quadrangle. Bedrock formations range in age from Triassic to Cretaceous. The details not available on previous geologic maps include: four alluvial terrace units, two lacustrine units, two mass movement units, and members of the Moenkopi, Chinle, and Carmel Formations. Historically the Page Sandstone has been mapped as part of the Navajo Sandstone or the Carmel Formation. This map identifies the Page Sandstone as a separate and independent unit. The Deer Point quadrangle is cross cut by a portion of a Laramide-age, basement cored, NNW-SSE trending asymmetrical anticline called the Waterpocket Fold. Strikes and dips measured throughout the Deer Point quadrangle identify the vergence of the anticline as eastward with a maximum dip of 49˚ on the forelimb and 7˚ on the backlimb. The maximum dip on the forelimb dramatically decreases in the southern quarter of the quadrangle to 15˚.The Utah Geological Survey is mapping the Hite Crossing 30' x 60' quadrangle at a scale of 1:62.500. The Deer Point quadrangle is one of 32 quadrangles that comprise the Hite Crossing quadrangle. The Utah Geological Survey is working to establish erosion rates on the Colorado Plateau. To do this, they are dating alluvial terrace deposits. Within the Deer Point quadrangle four new terrace levels have been identified that could help with this research. Additional research could use these terrace deposits to better understand erosion rates in the Deer Point quadrangle and the broader Colorado Plateau. Numerous mass movement deposits are found within the Deer Point quadrangle. The largest has been named the Red Slide. Several aspects of the Red Slide are identified including classification, breakaway zone, source, deposit size, composition, debris flow path and depositional history. The Red Slide has been classified as a debris flow. The breakaway zone is a concave cliff 1.5 miles (2.4 km) to the west of the debris flow's present location. The flow's scarp is no longer identifiable. The source of the debris flow material is the Chinle Formation and Wingate Sandstone. The Red Slide deposit covers an area of over 16.6 million ft2 (~1.5 million m2). The toe of the debris flow is 1 mile (1.6 km) wide. The estimated maximum thickness of the debris flow is sixty meters. The Red Slide is composed of fine-grained, clay- and silt- sized material, and a small amount of angular pebble- to cobble-sized limestone clasts from the Owl Rock Member of the Chinle Formation. Boulder- to sand-sized grains from the Wingate Sandstone are scattered throughout the deposit with the larger grains forming inversely grading packages. The Red Slide likely occurred as a series of large debris flows, not one catastrophic event, although they may have occurred at about the same time.

Degree

College and Department

Physical and Mathematical Sciences; Geological Sciences

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