THE ORIGIN OF SOUTHERN AFRICAN COASTAL LAKES

Summary

There are two groups of southern African lakes, a southern group made up of the Wilderness lakes and a north-eastern group comprising lakes on the Natal, Zululand and southern Moçambique coastal plain. Bathymetric maps are presented for representative lakes of these two series. There appear to be three types of lakes with respect to origin. Most of the lakes represent drowned valleys associated with river systems. Evidence is presented to show that St Lucia, although 1 to 2 m deep at present, was originally much deeper. The narrow coastal lakes of southern Moçambique are interpreted as low-lying land inundated as a result of rise in sea-level. The third type of lake is typified by Rondevlei at Wilderness; this lake apparently originated as a deflation basin.