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This paper presents results of a study of aeolian erosion at the landscape scale. There have been few such studies in desert geomorphology compared to those focused on individual landforms and on rock surface sculpture.

The present study area lies in the southern part of the Libyan Desert in south-central Egypt, between 25 degrees and 27 degreesN, 29 degrees and 30 degreesE. Bedrock comprises Paleogene limestone of various lithologies. Climate is hyperarid.

The following topics are treated.

(i) Correspondences between rock outcrop belts and belts of terrain lineated by aeolian erosion and unlineated terrain.

(ii) The effect of lithology on aeolian lineation, which works through the presence or absence of chert in the limestones. Lineation is produced by aeolian erosion in chert-free/poor rocks, whereas erosion of chert-rich rocks produces a desert pavement that armors the surface, suppressing erosion.

(iii) The effect of large valleys eroded upwind of lineated terrain, which deflect winds and trap sand, ending erosion, so that downwind lineations are reduced and finally erased by weathering.

(iv) Sample lineated landscapes in the area show stages of evolution, arranged in the time domain into a proposed cycle of aeolian erosion; the cycle progresses from initial smooth plain to grooves separating long, blade-shaped ridges, to segmentation of ridges into shorter blades along diagonal joints, to streamlining of shorter blades and size reduction, to final planation. In any one wind-parallel swath of lineated terrain, stages in the cycle progress downwind in the space domain, so that upwind landscapes are more advanced in the cycle.

(v) The structure of air flow responsible for lineation is still uncertain, but initial grooving may respond to stable longitudinal horseshoe vortices, or self-organized regularity of erosion by random vortices; subsequently, the erosion pattern is fixed by evolving relief.

(vi) Large, smooth basins within the lineated terrain were carved by aeolian erosion before Oxygen Isotope Stage (OIS) 5 (70-130 ka), as were similar basins along the Dakhla piedmont below the scarp; little geomorphic change has occurred since, so in this field of aeolian erosional lineations (AELs) the aeolian erosion cycle may have occupied 10 times as long. Since continental scale aridity set in at ca. 2.4 Ma, there have been only two cycles in this area. A completed cycle earlier than the current incomplete one is indicated by rare small yardangs riding ’piggyback’ on larger ones. (C) 2001 Elsevier Science B.V. All rights reserved.