NEW MAPPING OF THE EAST HALF OF THE LOA 30'X60' QUADRANGLE

The Utah Geological Survey recently completed a new detailed geologic map of the east half of the Loa 30' x 60' quadrangle. The map encompasses an area on the Colorado Plateau Province that includes part of Capitol Reef National Park and it's famous Waterpocket Fold where Triassic and Jurassic formations have been folded and are beautifully exposed. The map also includes the Fremont River drainage basin, volcanics of Boulder Mountain and Thousand Lakes Mountain west of Capitol Reef, the Caineville Reef, and igneous dikes and sills exposed in and near the northern part of Capitol Reef National Park. The mapping area covers a series of monoclines, anticlines, and synclines that trend generally north-south. We mapped formation contacts and differentiated members of the Triassic Moenkopi and Chinle Formations, the Jurassic Carmel and Morrison Formations, and the Cretaceous Mancos Shale. The map shows the basalt and latite lava flows on Boulder Mountain and Thousand Lakes Mountain, trachyte lava flows on Hens Hole, and surficial alluvial, eolian, mass wastage, and glacial deposits. We also identified Tertiary units (upper Eocene, Duchesnean) on the flanks of Thousand Lakes Mountain that were previously unmapped. We compiled field mapping on sixteen 7.5-minute quadrangles, scanned and vectorized the maps, and then stitched them together to create the 1:62,500 scale map. The UGS and the USGS STATEMAP component of the National Cooperative Geologic Mapping Program provided funding for the project.