Geomorphic evidence for late Quaternary environmental change from the eastern Great Karoo margin, South Africa

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The eastern margins of the Great Karoo, South Africa, represent a transition zone between the semi-arid shrublands of the Karoo to the west and the moister grasslands of the east. For this reason, the surficial sediments and younger geomorphic features of the area might reliably be expected to record evidence for environmental change, particularly with regard to the precipitation record and phases of greater aridity as the boundary of the Karoo migrated in response to climate change during the Late Quaternary. The high altitude catchment on which we report here is situated on the inland flank of the upwarped South African Great Escarpment, which here forms the Stormberg range. The catchment is unique in that a number of geomorphic features have, within their structure, preserved evidence of aeolian, fluvial and colluvial processes, which were active in the past. We present evidence from a variety of depositional landforms and sedimentary deposits that suggests that Late Quaternary climates in the eastern Karoo have been both moister and significantly more arid than at present, as well as displaying a greater seasonality in rainfall.