DRAKENBERG 241 



is concerned, by an exaggerated evaporation, and woods of 

 a marked deciduous and temperate type are confined to 

 the bottom of the valleys. The landscape of the Draken- 

 berg is thus one of grassy dales and gorges varied with 

 shrubs and perennial herbs, typical pastoral scenery. 



Kalahari. The strength and moisture of the south- 

 eastern trade winds are exhausted before the central 

 and western portions of South Africa are reached : the 

 westerly winter storms, on the other hand, exercise but 

 little influence over these portions. Thus the vast regions 

 lying to the south of the subtropical boschveld depend 

 for their life-stirring moisture mostty on local winds 

 and storms, or again on north winds and sea-breezes 

 which cool in winter on reaching the high plateau. 

 Hence the extension of broad, arid lands, the dry char- 

 acter of which goes on increasing from east to west, so 

 as to reach a truly desert condition on the Atlantic 

 coast. The average rainfall oscillates about four inches, 

 but is very irregular from year to year. The Kalahari 

 is the largest of those regions and occupies the centre 

 of the high tableland. West of the boschveld of 

 Rhodesia and Transvaal the trees are gradually more 

 scattered and lower, and the grass is thinner and shorter. 

 Now table-like tops and vast plains may be seen bare 

 and rocky or with a ragged mat of poa grass. Thorn- 

 bushes, especially the acacia with its tusk-shaped thorns, 

 form loose thickets in the dry beds of the streams, amid 

 wiry tufts of dry andropogon and aristida grasses. In 

 similar situations the tree euphorbia and the aloe, with 

 a small number of low, heath-like, woody trees and 

 short sage-bushes are thinly spread over the whole 

 area of the Kalahari ; the only portions which are 

 really plantless are the valleys or level depressions and 

 dry salt pans, for scattered succulents speckle the stony 



1169.1 B, 



