HOLOCENE AEOLIAN ACTIVITY IN THE SOUTHWESTERN KALAHARI DESERT, SOUTHERN AFRICA - SIGNIFICANCE AND RELATIONSHIPS TO LATE-PLEISTOCENE DUNE-BUILDING EVENTS

Little is known about the timing of dune-building episodes in the sout hwestern Kalahari Desert. Previously, arid phases when dune activity o ccurred have been inferred from gaps in chronologies derived from info rmation that attests to former humid periods. To redress this, optical ly stimulated luminescence (OSL) dating was applied to sediment sample s taken from a range of aeolian landforms in the SW Kalahari. Four per iods of dune building are identified in the late Pleistocene and Holoc ene. Holocene aeolian activity at 6 ka and 1-2 ka led to the construct ion of localised dune forms, in contrast to late Pleistocene times whe n the extensive field of linear dunes that dominates the region was em placed. Late-Holocene aridity was however sufficient to allow rapid em placement of the lunette dune at Witpan. The record of aeolian activit y is evaluated in the context of humid chronologies and an ocean-atmos phere model of Holocene climate change, with good agreement obtained. It is concluded that the application of optical dating to a range of a eolian landforms has the potential to establish the style as well as t iming of dune-building. It is also demonstrated that the climate durin g dune-building periods must have differed significantly from the prev ailing semi-arid climate with drought periods of today, which may have been the predominant climate regime through much of the Holocene.