456 OSCILLATION OF THE COAST LINE 



of the periods of plain-cutting ; there is as yet insuffi- 

 cient evidence to correlate these phenomena definitely, 

 but it may well be that the higher shore terraces, such 

 as that covered by the marine gravels of the Zwartkops 

 Heights, and the old beach underlying the limestone of 

 Cape Infanta, were removed out of reach of the waves 

 when the inland plateaux, 1,000 feet above the modern 

 river beds, were elevated. 



The numerous S-curves of the southern river valleys 

 with precipitous sides, often several hundred feet high, 

 are relics of the time when the streams meandered slowly 

 across nearly flat plains ; on the fall of the streams being 

 increased by the rise of the land their downward cutting 

 power was renewed and they deepened the valleys in 

 which they flowed, so that in many cases the S-bends 

 were retained and deepened to the extent we now see. 

 One of the most remarkable of these is the S-shaped 

 gorge in the Klein Zwartberg occupied by the Buffel's 

 River ; another has been cut Jby the Gamka between 

 the Roode Berg and the Pogha Hills ; from the Eastern 

 Province the extremely sinuous and deep valleys of the 

 Great Fish, Kei and Bashee Rivers are analogous 

 examples. 



Hitherto we have only given the evidence for eleva- 

 tion of the land relatively to the water in connection 

 with the superficial deposits. There is, however, evi- 

 dence of a contrary movement ; the great depths of the 

 estuarine shelly sands and muds near the mouths of 

 some of the rivers, especially the Zwartkops and Buffalo 

 Rivers, which are the only ones that have been explored 

 in this sense, may be due to depression. On the west 



