394 SAND 



Gordonia and in Bechuanaland the surface of the sandy 

 country is often flat or very gently undulating over 

 large areas. At Pepani, a few miles south of Morokwen, 

 a well sunk on flat sandy ground penetrated 130 feet of 

 loosely consolidated sand with a few hard lumps formed 

 by the cementation of the sand by opaline silica, and 

 two other wells on the same farm passed through 50 

 and 130 feet of sand respectively. Even if the moder- 

 ate figure of 20 feet be taken as the average depth of 

 the sand in Gordonia and the west of Bechuanaland the 

 whole amount is very great. The chief source of the 

 sand is undoubtedly to be found in the hills which 

 formerly existed there and which are now in part re- 

 presented by the isolated ranges in the South-Eastern 

 Kalahari, such as the Scheurbergen, Korannaberg, 

 Langebergen and the Heuning Vlei Range. The 

 amount brought down by rivers from outside the region, 

 the Molopo, Nossob and Kuruman Eivers, was probably 

 small compared with that produced in the district it- 

 self. At the present time the products of denudation 

 in this region are not removed by rivers, the wind is the 

 only agent of transport, and probably the amount blown 

 away is counterbalanced by that brought in. At some 

 former period the sand seems to have been freer to move 

 about than now, for it seems unlikely that the great 

 dunes which are now covered with vegetation could 

 have been formed under conditions in all respects like 

 those of to-day. 



In Prieska the granite, gneiss and mica-schist areas 

 are usually covered with sand. A well-defined and 

 narrow belt of red sand dunes extends up the Olifant's 



