The distribution and environmental implications of coversand deposits in the Southern Cape, South Africa.

Abstract

Aeolian coversands in the hinterland of the Swartvlei and Knysna estuaries in the southern Cape, South Africa, are differentiated from the aeolianite dune ridges of the Wilderness embayment and from the early Tertiary lignites and sands of the Knysna Formation sensu stricto . These medium- to fine-grained coversands have a maximum depth of ~ 6m on the remnant African Surface of the coastal platform. They thin over a distance of 6 to 8km inland to a depth of less than 0.5m. They also extend into headwater catchments and occur as a component of flood plain and estuary deposits. At least three phases of sand deposition can be recognised. In situ older sands are coherent where a lateritic palaeosol remains intact beneath a vegetation cover. After disturbance, the sands pose an environmental hazard in that they become highly mobile. Examples from recent excavations for construction purposes are provided.