Farouk El-Baz

Document Type

Article

Publication Date

1979

Abstract

The Western Desert of Egypt occupies nearly two-thirds of the country. Its general flatness is interrupted by depressions, most of which enclose oases. The rest is a vast plain of vegetation-free, wind-scoured terrain. As part of the Eastem Sahara, it represents one of the driest expanses on Earth. Thus, it is replete with evidence of prolonged aeolian activities, including a great variety of sand dunes and sand sheets. The vast amount of sand coupled with wind data from meteorological satellites, betray a prolonged history of aeolian transport from north to south. In the meantime, images from orbiting spacecraf, and topographic data from radar sensing show areas where water accumulated as lakes in low topography during humid periods in the geological past. Radar data also revealed numerous courses of now sand- buried rivers that flowed northward during wetter climates. Thus, it is proposed that such wet episodes resulted in the separation and rounding of sand grains. The latter were water-transported northward and deposited within topographic basins. As dry climates prevailed, the sand deposits were shaped into dunes by wind action. These relationships were revealed at sites throughout the desert. All those locations clearly display evidence of repeated interplay of fluvial and acolian processes from the late Phanerozoic to the Recent, particularly throughout the Quatemnary.

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