ABSTRACT
Each of the five major African rivers for some part of its course flows through, and receives drainage from, one or more of the great structural basins of the continent. Five main river systems will be discussed: those of the Nile, Niger, Congo, Zambezi and Orange. The evolution of the Niger’s course also involves the formation of a temporary inland lake. In the mid-Tertiary the upper Niger was a headstream of the Senegal river, until increasing accumulations of sand and gravel in the region north of Bamako forced the river to flow north-eastward into the centre of the Timbuktu Basin. The story of the Zambezi and Orange river systems is less well known, though it seems that their evolution is inseparably linked together. The early drainage of southern Africa appears to have been directed into the Kalahari Basin, including the upper Zambezi, the present Okovango, the Vaal and upper Orange rivers.
