The Ancient River System of the Kalahari and the Possibility of its Renewal

Abstract

MANY arid countries contain wide mud-floored depressions which mark the sites of former lakes. This origin is so obvious that, as in western Australia, they are called lakes, although waterless. In South Africa they are known as vleis or pans. In a paper on the dry-lake system of West Australia in 1914, I pointed out that the steady descent in level from one of these mud-flats to the next and their arrangement on converging lines indicates that the lakes are isolated sections of an ancient river system, which was broken up as the dwindling streams failed to keep open their channels. The same explanation gives the clue to the distribution of corresponding basins in Libya. Prof. E. H. L. Schwarz has adopted the same idea for the great pans and vleis in the interior of southern Africa. He represents the Atosha Pan, the basins of Lake Ngami and Makarikari, and two lines of depression across the Kalahari desert, as remnants of one great river system which had its sources in the highlands of southern Angola. Its headstreams, including the Chobi and the Okavango, flowed south-eastward, parallel to the present course of the Upper Zambezi. The river was diverted southward by the highlands of southern Rhodesia and the Transvaal, and discharged to the Atlantic through the Orange River.