Vol. 62.] 



IN THE SOUTH-WEST OE CAPE COLONY. 



71 



to the sea. The same thing is noticed in travelling : for the road 

 that has to be followed, in order to get from one place to another, 

 usually describes an immense circuit, but all on the level ; whereas 

 to go straight would necessitate climbing up and down a succession 

 of very steep hills. 



The plain, or the tops of the ridges which now represent the plain, 

 in the western part, is in places covered with surface-deposits. 

 Near the mountains there are heaps of great, rounded, water- 

 worn boulders, often cemented together in a siliceous matrix ; 

 farther away we find gravels with pebbles of all sizes, either loose, 

 or cemented by silica or compounds of iron ; still farther away 

 there are sandy clays, which, according to circumstances, harden on 

 the surface to an ironstone, or to a siliceous rock — burrstone, or 

 freshwater quartzite. 



Fig. 1. — Ironstone-gravel forming beneath the sour soil of the 

 Uplands plateau, seen in a railway -cutting south of George Town. 



D 



^^Mi^mMMS 



A = Quartz-vein traversing the rotten granite, Gr ; B flayer of subangular 

 fragments of vein-quartz; C=sand, cemented into a granular mass by 

 hydrated oxides of iron; D=grey sandy soil ; E= humus. 



[Compare the description of ironstone found beneath the sandy soil of 

 Wolmer Forest, in Gilbert White's ' Natural History of Selborne ' letter iv, 

 1st series.] 



To the east — or, to be precise, from George Town to Port Elizabeth 

 — the* plateau-form becomes much more prominent ; the rock out of 



