Abstract:

The Kalk Bay Mountains of the southern Cape Peninsula, South Africa, show marked development of pseudokarstic features such as caverns, dolines and grikes. These features have formed over at least 100 million years on supposed inert quartzitic sandstones of the Peninsula Formation of the Table Mountain Group. Pseudokarst on sandstone is relatively rare world-wide and various aspects of cave genesis are highlighted in the Cape Peninsula. Cape Peninsula pseudokarst is relict, occurs at high altitudes above the present water table and could provide clues to palaeoenvironmental conditions during the African erosion period.
The cave systems in the Kalk Bay Mountains occur in at least three levels in the thickly-bedded sandstone. These different levels are the result of differential uplift during the Miocene and Pliocene. The Cape Peninsula Mountains are tabular and blocky, as opposed to the fold mountains of the rest of the South Western Cape. Much more of the overlying sedimentary layers in the Cape Peninsula have also been removed by weathering and erosive processes. The caves can be compared to similar pseudokarst features on sandstone in areas such as Gran Sabana, Venezuela. The acidic water chemistry in Venezuela contributes to a very intensive weathering environment. Present day humid tropical conditions in Venezuela are likely to be similar to palaeoclimatic conditions in the Kalk Bay Mountains, contributing to sandstone cave genesis.