414 ORIGIN OF PANS 



and Belmont. On the clay floors coarse sand cannot 

 obtain a lodgment ; this is proved by the breaking of the 

 continuity of a long belt of north-westerly trending 

 sand dunes by the Verkeerde Vlei pan near Van Wyk's 

 Vlei. On the leeward side of the pan the width of the 

 belt of dunes is more than twice that on the windward 

 side. Another peculiar feature in connection with these 

 pans is the fact that inblown red sand rapidly loses its 

 colour, the bleaching being due to the removal of the 

 ferric oxide forming a film round the sand grains or fill- 

 ing minute crevices in them. 



The amount of the depression below the surrounding 

 country is often very slight, but sometimes it may be as 

 much as 200 feet. Several pans in Hopetown, namely 

 Krantz Pan, Vogelstruis Pan and Koode Pan, are sunk 

 abruptly, and the north-western rim in each case is 

 a cliff capped with the calcareous tufa which covers the 

 surrounding country. The origin of these escarpments, 

 rising as much as 150 feet above the floors of the pans, 

 is due to the weathering of the shales below the hard 

 tufa and the transport of the disintegrated material by 

 the prevailing wind to the opposite side of the pan. 



Pans are found on practically every formation in the 

 north, but they are most numerous in the Dwyka, and 

 are abundant on the Ecca. In a large number of cases 

 pans are due to the complete or more usually to the 

 partial removal of the Dwyka shales and tillite from 

 basin-shaped hollows in the Pre-Karroo surface, e.g., 

 Swingel's Pan (Hopetown) ; more frequently a ridge of 

 hard rock is exposed on one side only, e.g., the salt 

 pan at Biverton. Pans may form on the junction of 



