The Upper Quaternary of the Cape Flats Area (Cape Province, South Africa)

Palynological data and other evidence suggest that the Upper Quaternary of the Cape Flats area can be subdivided chronostratigraphically into units that may be correlated with those of the Northern Hemisphere. Five intervals have been identified in the Middle Pleniglacial and formal names are introduced for these intervals. During three of them, the MILNERTON, KILLARNEY and BLOUBERG intervals, the vegetation had a xerophytic character and is comparable with that of the Holocene. During the intermediate periods, the SALTRIVER and DIEPRIVER intervals, an extension of the mixed Podocarpus (Knysna) forest to the Cape Flats area took place. These changes in vegetation can be explained by differences of effective precipitation. Two periods of sedimentation, corresponding with periods of marine transgression, can be distinguished, viz., a Middle Pleniglacial and a Holocene one. During the Middle Pleniglacial the relative sea-level lay between 24 and 18 m below the present one; a later rise of the continent probably influenced the sea-level, so that the real position of the sea-level was even lower. During the Upper Pleniglacial, when the sea-level was very low, erosion was active in the Rietvlei basin. However, there are indications that inland dunes were formed on the Cape Flats area during that period. Sea-level fluctuations and sedimentation changed the drainage pattern of the Diepriver basin and evidence of two former outlets have been found. The paralic sediments that have now been dated as Last Glacial and Holocene, are named herein the CAPE FLATS FORMATION. This formation lies unconformably on the Praecambrian and Palaeozoic basement.