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  • Print publication year: 2016
  • Online publication date: June 2016

6 - Quaternary environmental change on the southern African coastal plain

Summary

Abstract

The low-lying South African coastal plain, bounded by the sea and by high-relief terrain of the continental interior, forms an important habitat for many animals, including humans. The present-day coastal plain is generally narrow, but expanded in width when sea level was lowered by between 75 and 130 m during Quaternary glacial periods. During these periods there was moderate expansion of the western and eastern coastal plains, whereas the southern coastal plain expanded by up to a factor of five onto the adjacent Agulhas Bank to form a continuous coastal plain. The offshore marine geology in this region allows for extrapolation of modern vegetation biomes onto comparable substrates exposed on the glacial-age coastal plain. With the exception of cemented dunes (aeolianite), Quaternary deposits on the exposed shelf are generally highly reworked and condensed. However, meandering rivers, wetlands and lakes on the low-lying southern coastal plain can be inferred, and may have provided a refuge from the dry interior during glacial periods. The southern coastal plain possibly served as a geographical region of origin by periodically isolating populations over glacial to interglacial cycles, promoting human evolution.

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