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). |
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Page 37
... indicate stratification by simultaneous extinction between crossed nicols parallel to a single direction . Even under considerable magnification ( 360X ) , the preferred orientation of fine mica minerals may be observed to parallel ...
... indicate stratification by simultaneous extinction between crossed nicols parallel to a single direction . Even under considerable magnification ( 360X ) , the preferred orientation of fine mica minerals may be observed to parallel ...
Page 55
... indicate that : ( 1 ) a ratio of bulk density to specific gravity may be used as a measure of compaction ; ( 2 ) the ... indicated in part by the compaction ratio ; ( 5 ) the stability of a crust , that is , the rate at which water may ...
... indicate that : ( 1 ) a ratio of bulk density to specific gravity may be used as a measure of compaction ; ( 2 ) the ... indicated in part by the compaction ratio ; ( 5 ) the stability of a crust , that is , the rate at which water may ...
Page 71
... indicated by the inverse relationship between nonstructural water and colloidal - size particles . This latter ... indicate that only limited capillary action is available to subsurface water . A low water table would necessarily ...
... indicated by the inverse relationship between nonstructural water and colloidal - size particles . This latter ... indicate that only limited capillary action is available to subsurface water . A low water table would necessarily ...
Contents
ENVIRONMENTAL SETTING AND GENERAL SURFACE | 1 |
MINERALOGICAL FEATURES OF MOJAVE DESERT PLAYA | 31 |
HYDROLOGIC TYPES OF PLAYAS AND CLOSED VALLEYS | 73 |
3 other sections not shown
Common terms and phrases
50 percent clay alkali stain amount anomalies argillic playas Basin and Range Basin-Range 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 Leach Mabey material Mexico MILLIGALS mineralogy Mojave Desert montmorillonite MOUNTAINS 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