Geology, Mineralogy, and Hydrology of U.S. PlayasTerrestrial Sciences Laboratory, Air Force Cambridge Research Laboratories, 1965 - Arid regions - 176 pages Playas (dry lake beds), the flat central portions of desert basins, are landforms which have unique properties. Most of those in the U.S. were sites of larger Pleistocene lakes, and are characterized by fine-grained lacustrine silt and clay, with secondary saline, sulfate, and carbonate minerals. The playa surfaces are essentially level, but hydrologic, tectonic, and climatic forces are continually modifying them. A variety of surface features representing a range of influence of the arid environment have been noted; these features are subject to change in response to a changing environment. Playa basins have been studied in the field using the geophysical methods of gravity, seismology, electrical resistivity, and magnetism. This report is a collection of six individual papers discussing the environment and surface features, mineralogy, hydrology, structure, geophysics, and airphoto features of playas. (Author). |
Contents
ENVIRONMENTAL SETTING AND GENERAL SURFACE | 1 |
MINERALOGICAL FEATURES OF MOJAVE DESERT PLAYA | 31 |
HYDROLOGIC TYPES OF PLAYAS AND CLOSED VALLEYS | 73 |
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Common terms and phrases
50 percent Clay alkali stain amount anomalies argillic playas Basin and Range Basin-Range bedrock Bouguer anomaly Calif California capillary carbonate Cenozoic chlorite classification clay minerals clay playas clay-size closed valleys compact crust crustal samples crustal types Death Valley deposition depth discharge occurs dry playas dry-surfaced erosion evaporation Figure fine-grained fissures flooding ratio Garlock Fault Geological geophysical giant contraction polygons gravity ground water ground-water discharge ground-water-discharging playas hydrologic illite indicate interlayered kaolinite KNOOP VALUE Lavic Mabey material Mexico miles MILLIGALS mineralogy Mojave Desert montmorillonite Nevada Nonstructural Water Panamint particle-size distribution permeability phreatophyte mounds phreatophytes piezometric piezometric surface playa crusts Playa Lakes playa sediments playa surface Playa Type Based Pleistocene Pleistocene lake polygons Province refiltration relatively Rogers Rosamond saline saline content Salt Pavements Searles sediments seismic silt structure Survey Water-Supply Paper tectonic topographic U. S. Geol underlain Valley Playa water table water-table Willcox Playa zone