Philip A. Davis
United States Geological Survey
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Featured researches published by Philip A. Davis.
Remote Sensing of Environment | 1993
Philip A. Davis; Carol S. Breed; John F. McCauley; Gerald G. Schaber
Abstract We used a decorrelation-stretched image of Landsat Thematic Mapper (TM) Bands 1, 4, and 7 and field data to map and describe the main surficial units in the hyperarid Safsaf region in south-central Egypt. We show that the near-infrared bands on Landsat TM, which are sensitive to very subtle changes in mineralogy common to arid regions, significantly improve the geologists capability to discriminate geologic units in desert regions. These data also provide the spatial and spectral information necessary to determine the migration patterns and provenance of eolian materials. The Safsaf area was the focus of our post flight field studies using Shuttle Imaging Radar (SIR) data following the discovery of buried paleochannels in North Africa. Most of the channels discernible on SIR images are not expressed in TM data, but traces of a few channels are present in both the SIR and the TM data within the Wadi Safsaf area. Here we present a detailed digital examination of the SIR and the TM-band reflectance and reflectance-ratio data at three locations of the more obvious surface expressions of the buried channels. Our results indicate that the TM expressions of the channels are not purely topographic but are more compositional in nature. Two possibilities may account for the TM expressions of the buried channels: 1) concentrations of windblown, iron-rich materials that accumulated along subtle curvilinear topograpohic traps, or 2) curvilinear exposures of an iron-rich underlying unit of the flat sand sheet.
Journal of Geophysical Research | 1988
Kenneth L. Tanaka; Philip A. Davis
Journal of Geophysical Research | 1980
Philip A. Davis
Journal of Geophysical Research | 1984
Philip A. Davis; Laurence A. Soderblom
Journal of Geophysical Research | 1986
Paul D. Spudis; Philip A. Davis
Open-File Report | 1993
Kenneth L. Tanaka; H.J. Moore; G.G. Shaber; Mary G. Chapman; E.B. Stofan; D.B. Campbell; Philip A. Davis; John E. Guest; G.E. McGill; P.G. Rogers; R.S. Saunders; James R. Zimbelman
Journal of Geophysical Research | 1990
Philip A. Davis; Matthew P. Golombek
Journal of Geophysical Research | 1987
Philip A. Davis; Paul D. Spudis
Icarus | 1995
Philip A. Davis; Kenneth L. Tanaka; Matthew P. Golombek
Journal of Geophysical Research | 1985
Philip A. Davis; Paul D. Spudis