oa Annals of the Natal Museum - Pleistocene shorelines in the southern and south-eastern Cape Province (Part 1)

Volume 21, Issue 1
  • ISSN : 0304-0798



This paper will descriptionbe the quaternary shorelines where exposed along the southern Cape coast, from the Natal border to Cape Town. In the first part all the shorelines in the Transkei and Ciskei are discussed, and the higher ones, at 30 m or over, from the Great Fish River to Cape Agulhas. Most of the sites mentioned are marine or estuarine; reference is made to riverine gravels where there has been a careful study of their relation to contemporary sea-levels. In order to establish chronological correlation with sites in the interior and with other parts of the world, stress is laid on artefacts included in marine gravels. The quaternary molluscan sequence in Southern Africa is poorly known, and little fauna has been found in the high-level beaches here discussed. It is assumed that the Cape shorelines have been eustatically controlled, and were formed during (usually northern) interglacials; but this pattern is superimposed on a continuous emergence which may be due to local epeirogenesis or to sinking of the ocean-floor or both. The more recent shorelines would be separated by eustatic low sea-levels, for which at present there is little evidence in South Africa. Before the 60-metre shoreline (= perhaps the Cromer interglacial) eustatic marine regression was small and there was continued emergence with little fluctuation. The gravels of the 6O-metre shoreline occasionally yield rolled primitive hand-axes. It appears that this shoreline has undergone practically no local warping between the Natal border and St. Francis Bay and west of Mossel Bay; but the Tzitzikama, Outeniqua and Robberg ridges have been uplifted by 40-60 m. Along this stretch it is uncertain if even the 30-metre shoreline can be recognized at its regular altitude; but the 18-metre shoreline can be traced all along the coast, which since that time has been stable. In the 30-metre gravels are occasionally found Acheulian tools. There are probably traces of a 48-50 metre shoreline, less clearly marked than those at 30 m and 60 m. Above 60 m there are occasional occurrences of marine gravels, rarely containing rolled pebble-tools; but they make no pattern, and in the Early Pleistocene there may have been regional warping and uplift on stretches other than the Tzitzikama and Outeniqua ranges. It has been claimed in Algoa Bay. The con­tained pebble-tools are adiagnostic and cannot be used as zone-fossils to separate one shoreline from another. Near Riversdale are at least five shorelines, for which are suggested correlations on altitude alone with the four recognized in Natal. Shorelines above 150 m are probably tertiary.

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