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Program Manager: Grant C. Willis (UGS) Project Manager: Robert F. Biek (UGS) GIS and Cartography: Jay C. Hill, Kent D. Brown, J. Buck Ehler (UGS) Geology review: Grant C. Willis, Robert F. Biek, Michael D. Hylland (UGS)
GIS review: Buck Ehler (UGS) Funding: Utah Geological Survey and the U.S. Geological Survey, National Cooperative Geologic Mapping Program, through USGS STATEMAP award number 06HQAG0037. |
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This digital dataset represents the geology of the White Hills quadrangle at 1:24,000 scale. Strata in the quadrangle dip an average of seven degrees to the northeast on the west flank of the very broad, poorly defined St. George syncline. The strata are locally folded into small anticlines and synclines, the more chaotic of which were caused by dissolution of gypsum beds. Many breccia pipes and linear collapse structures create synclines that are subparallel to the regional dip. Several small normal faults displace rocks only a few feet and are considered products of local dissolution rather than deep-seated structures. Caves form along joints and small-displacement faults in massive Permian limestone with limited, perhaps very deep, dissolution. The Virgin River flows westward along the south edge of the quadrangle, exposing only the top of the Permian Queantoweap Sandstone and the Toroweap Formation in the river gorge. The Permian Kaibab Formation covers the southwest third of the quadrangle, and varies in thickness because of subaerial erosion during the time of the major Permian-Triassic unconformity. The Triassic section includes the Moenkopi Formation, which unconformably overlies this paleotopography, and the Chinle Formation. The Jurassic Moenave Formation is poorly exposed in the northwest corner of the quadrangle. Only the south end of the Quaternary Santa Clara basalt flow reached the quadrangle as it flowed down stream drainages from the north. This erosion-resistant basalt is beginning to form an inverted valley. Uplift and downcutting are also documented by incised alluvial-terrace deposits along the Santa Clara and Virgin Rivers and their tributaries. This item is part of a larger digital dataset that contains the additional feature classes, base maps, plates, and other supplementary materials necessary for the user to fully view, evaluate, and utilize the geological spatial data related to this product. A paper version of this map is available from the Utah Department of Natural Resources Map and Bookstore. |