TERTIARY AND RECENT DEPOSITS 395 



Vlei Kiver (near Van Wyk's Vlei) in a south-easterly 

 direction becoming wider and spreading out in Victoria 

 West. Patches of heavy red sand are common in Brits- 

 town, Hopetown and Kimberley. 



In Bushmanland (parts of Namaqualand, Calvinia 

 and Kenhardt) the sand is derived from the minerals 

 composing the gneissose granite that occupies such 

 wide areas there. Quartz and felspar are the chief con- 

 stituents, and by the breaking up of the granite under 

 the influence of the great diurnal change of temperature, 

 one of the climatic features of that region, the minerals 

 are set free to be carried about by the wind and rain. 

 The sand is pink owing to the abundance of red 

 felspar, and also to the iron oxide derived from the fer- 

 ruginous constituents of the igneous rocks, biotite, 

 hornblende, hypersthene and magnetite. 



In the district between the Olifant's Biver mouth and 

 the Berg Biver, as far inland as Piquetberg and the 

 Olifant's Biver Mountains, there is a great quantity of 

 sand. The country is known locally as the Sand Veld. 

 The underlying rock is chiefly Table Mountain sand- 

 stone, although the southern part of the area is prob- 

 ably underlain by the Malmesbury beds. The whole 

 area is characterised by a remarkable scarcity of run- 

 ning water and even of definite stream beds, although 

 the southern part at least has a fairly heavy rainfall ; 

 the northern portion is much drier, but the absence 

 of stream beds is due to the rapidity of absorption of 

 the water by the ground and not to the lack of rain. 

 From the Berg Biver to the Olifant's, a distance 

 of some seventy-five miles in a straight line, there are 



