Geomorphological Evolution of the Pilanesberg

Abstract

The geomorphological evolution of the Pilanesberg Complex, an alkaline igneous body emplaced around 1,250 million years ago and subsequently exhumed by erosion, reflects the interplay of tectonic and climatic factors over very long time periods that have given rise to regional-scale patterns of geomorphological processes and resultant landforms. The topography and river patterns of the Pilanesberg region have evolved by progressive denudation of Karoo sedimentary rocks (<30 Ma), revealing evidence for a much older, relict land surface that may have been formed during the Dwyka glaciation around 300 million years ago. The absence of significant placer deposits of gold, platinum and chromium is explained by this proposed model.