The Megageomorphology of the Radar Rivers of the Eastern Sahara

The Eastern Sahara (Fig. i) is devoid of surface drainage -this unusual characteristic distinguishes its morphology from that of most other desert regions where running water dominates landscape development (Peel, 1939). Cyclic aridity, which is responsible for the obscuring eolian blankets and wind-erosion effects, had set in by the Pliocene-Pleistocene transition, about 2 million years ago (Williams, 1982). SlR-A/B reveals, however, that the "bull's-eye" of aridity in North Africa underwent a long prior history of erosion by southwestward-trending Tertiary streams (McCauley et al., 1986; Schaber et al., 1986).