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Paleosols on a Fluvial Terrace at Driekop, Lebowa, South Africa as Indicators of Climatic Changes During the Quaternary
E. VERSTER and Th. VAN ROOYEN, Department of Geography, University of South Africa, P.O.Box 392, Pretoria 0001, South Africa.
An exposed terrace more than 11 m thick along the Moopetsi River at Driekop (30o11'E, 24o38'S and 800 m above sea-level) was investigated with the objective of evaluating the depositional history of the area and, in turn, reconstructing past terrestrial ecosystems and environments.
A total of 12 soils layers, each with different morphological, chemical, physicals and mineralogical properties, including a soft calcrete layer and the presence of both LSA artefacts and Iron Age fragments are features on the terrace's stratigraphy. It is obvious that most of these layers are paleo features which made provide data for the stratigraphic reconstruction and climatic history of the area. The genesis of the terrace is ascribed to distinct events including cyclic periodicities involving deposition, erosion and various intensities of pedogenesis. Radiocarbon dates for the calcrete and other calcareous materials range in age from 24 100, 18 000, 12 280 to 4 220 years BP and probably indicate drier periods, whereas a reddish, weakly structured soils probably represent more humid weathering conditions. On the other hand, two dark coloured, vertic clay soils (one at a depth of 2 m and the other at 9 m) are evidence of ecosystems conducive to smectite formation. All the data are used to construct a tentative framework in which paleosols and possible associated environmental conditions of the past are equated.
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