Farouk El-Baz

Document Type

Article

Publication Date

1998

Abstract

Space photographs allow the distinction of desert surface colors, which are caused by mineralogical variations. In the case of the Arabian Peninsula, these photo- graphs clearly distinguish the mountainous western, southern and northeastern parts, as well as the sand seas of the Nafud Desert and Ar-Rub Al-Khali. The sand in the depres- sions that enclose these sand seas was deposited during humid climates through fluvial channels. Much like the case of the castern Sahara, the humid phases alternated with dry climates dating back to 320,000 years ago; the last humid phase persisted between 10,000 and 5000 years ago. During dry episodes, the wind reshaped the flat deposits into sand dunes. This suggests that the depressions may host vast amounts of groundwater, which would have accumulated by seeping through the underlying rocks. In cases where the pa- leo-channels lead directly to the sea, fan deltas are formed at the coastline. This is clearly illustrated in the case of the desert plain of the Emirate of Dubai just west of the Oman Mountains. In such cases, the recognition of the courses of the paleo-channels may also indicate a potential for groundwater, particularly in fracture zone aquifers. Therefore, the study of the origin and evolution of sand deposits in the Arabian Peninsula, in both space and time, has far-reaching implications to groundwater exploration in the future.

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