186 E. H. L. Schwarz — Plains in Gape Colony. 



These shelves cannot be other than surf cut : we see them 

 forming now along the shores by the action of the waves (figs. 

 1 and 2), the cliffs crumbling with the attack of the breakers, 

 and the fallen debris washed to and fro with the perpetual 

 surge that desolates this treacherous coast-line ; the ledge thus 

 cut is sometimes washed bare, at others covered with what is 

 really a coral reef, but in which the lime-secreting organisms 

 are the red algae, shells and worms. Behind the actual coast 

 the individual ledges may attain a width of 30 miles as at 

 Caledon, but near Port Elizabeth they are much narrower, 

 seldom reaching five miles in width, while the subsidiary 

 smaller ledges are much less. It is this narrowness that struck 



Fig. 1. Arch and cave along the Knysna coast, near Seal Point, Cape 

 Colony. The rock is quartzite belonging to the Table Mountain Series. The 

 undermining of the cliffs by the battery of the waves is shown, but the 

 coast ledge cut by the dragging to and fro of the debris is covered at high 

 tide. The top of the cliffs belongs to the 700-foot ledge and is here about 

 600 feet above sea-level. 



me while examining the country in the Zitzikamma, a coast 

 district east of Port Elizabeth, and induced me to revert to 

 my original idea of their being surf cut, after having tempo- 

 rarily thought them to be plains of river erosion, for it is 

 impossible for a shelf to be cut by a river when the fall from 

 the mountains behind is so great and the course so short. 

 Besides this indirect evidence there are undoubted sea-beaches 

 left on these ledges to attest to their having been cut by the 

 surf. Over the flats one finds great beach bowlders between 

 which are wedged the broken shells of Pectunculus and other 

 marine forms, mostly of a sub-tropical aspect, foreign to the 

 shells now living along the coast ; elsewhere, as at Sandflats, 

 foraminiferal sand had collected in large masses and is used 



