The air is unusually dry, owing to the proximity of the Kalahari Desert on the west and to the interception on the east by the Drakensberg of the moisture bearing clouds from the Indian Ocean.
The western region, the Kalahari Desert, is mainly arid, with a sandy soil, and is covered in part by dense bush.
The greater part of Bechuanaland is covered with superficial deposits consisting of the sands of the desert regions of the Kalahari and the alluvium and saliferous marls of the Okavango basin.
A deposit of sinter and a calcareous sandstone, known as the Kalahari Kalk, considered by Dr Passarge to be of Miocene age, overlies a sandstone and curious breccia (Botletle Schnichten).
The chief centre in the western Kalahari is Lehututu.