The Kalahari Desert

The modern Kalahari Desert lies within the Kalahari sand beds - a massive expanse of sand that covers 1 630 000 sq km from just north of the equator to the banks of the Orange River in South Africa. The sand originated from rocks, lying in a shallow basin, that were eroded by wind over millions of years. The red colour of the dunes is caused by iron oxide, which covers each sand grain. The rainfall of the area is too low to reduce this iron oxide, and a wonderful variety of colours can be found in the desert sand.

The dunes of the Kalahari hide the ancient sedimentary rocks which are believed to be rich in fossil deposits. These dunes are fixed and are no longer moved by the wind. They do, however, owe their characteristic shape to the wind, which exposes the moist sand beneath . The moist sand is then eroded further. The sand that is removed, is deposited on the southwest side of the dune, which results in a more gentle gradient. These longitudinal dunes are called "seif dunes," an Arab word meaning ‘sword’.

The Ancient Nossob and Auob Rivers only flow for a short period during a very good rain season. A portion of the Auob River is said to flow approximately once every 11 years, the Nossob perhaps twice every 100 years. The Nossob River last flooded in the Kalahari desert in 1963 and the Auob in 1973, 1974 and 2000. They do, however, carry rainwater in the wet season and there is moisture beneath their beds, a precious resource that is tapped to sustain life in the area. The Nossob meanders a lot. In the north the riverbed is wide with slightly raised alluvial plains and widely flanking dunes. Further downstream between the Nossob and Twee Rivieren rescamps, the number of trees seem to dwindle and the course suddenly cuts through calcrete deposits turning south-westward. The Auob is charaterised by the beautiful stands of large grey camelthorn trees.

Temperatures in the desert vary greatly from -11 degrees Celsius on cold winter nights to 42 degrees Celsius in the shade on summer days when the ground surface temperature reaches a sizzling 70 degrees Celsius. Winter in the Kalahari is a cool, dry season from May to August, followed by a warm, dry season from September to October and then a hot, wet season from November to April.

My favourite time in the Kalahari desert is March.

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