The sedimentary fill of the structural Karoo Basin consists of a valley facies association, deposition of which was controlled by a highland topography, and a shelf facies association. The latter, locally overlying glaciotectonized bedrock, consists of four diamictite and two mudrock facies. Their distribution is attributed to glacial sediment input from the eastern highlands, from the south along the basin axis, and from a tectonic arc in the west, and changes in climatic setting.

The predepositional phase in the glacial history of the basin comprises expansion of the ice sheet onto the continental shelves. No sedimentary deposits are preserved in...