74 PK0F. E. H. L. SCHWAKZ ON THE COAST-LEDGES [Feb. I906, 



nature of the deposits, are found on the ledge from east to west, 

 and an explanation of its formation in one part must hold good for 

 the whole. As I think that we have evidence for ruling out the 

 possibility of river-erosion as a cause for the cutting of the ledge in 

 the Zitzikamma, so must we abandon the theory of the ruggens- 

 plateau being a peneplain. 



Another plateau, commencing on the east of Port Elizabeth, and 

 beginning at the sea- front with an elevation of some 150 to 200 feet, 

 is covered with undoubted marine shingle : it rises to 400 feet, 

 and at the base of the next plateau it is 460 feet above tide- 

 level. All over the plain there are these coarse boulder-beds, 

 sometimes associated with shell-deposits characterized by a large 

 Pectunculus. Most of the shells are of species living on the coast 

 at the present day, but the larger forms are now found only 

 along the Natal coast. On the top of the plateau and in the 

 surface-gravels, is a circular depression called the Groot Pan or 

 Zwartkop's Saltpan ; it annually fills with rain-water, which on 

 evaporation throws down salt of great purity, 100,000 bushels 

 being extracted yearly. I do not think we can say that this salt- 

 pan, by itself, is an argument in favour of the marine origin of 

 the plateau; though the simplest explanation of the occurrence 

 would be that the salt results from the leaching-out of the eva- 

 porated sea-water that was held up in between the boulders as the 

 beach rose above sea-level. The enormous amount held up in the 

 pan is the puzzling feature ; for the apparently-inexhaustible supply 

 would seem to necessitate a soil impregnated with salt in the 

 neighbourhood, yet the dense bush of prickly plants, aloes, 

 euphorbias, mimosas, scutias, etc., grows up almost to the water's 

 edge. The saltpans in Bredasdorp and at Bethelsdorp, nearly at 

 sea-level, seem also to receive an adequate explanation on the 

 theory that they are the result of sea-water evaporated and 

 impregnating the neighbouring soil ; but one can hardly so explain 

 the saltpans, at Prieska, for instance, which are hundreds of miles 

 away from the coast. 



In stating that there was no break from east to west in the 

 Uplands plateau, I spoke of the land as we have reconstructed it ; for 

 nowadays there are many gaps, caused by the inclusion of immense 

 deposits of loose Cretaceous rocks, which have readily yielded to the 

 impetuous torrents that coursed over the plateau. These deposits, 

 which we term Uitenhage Beds, are made up of a basement- 

 series of gravels known as the Enon Conglomerate, and of 

 sands, clays, and marls, characterized by Tceniopteris and Olado- 

 jpliltbis denticulata. They once covered a very much greater extent 

 than they do at present, but after their deposition some extraordinary 

 cross-folding took place, which let them down in hollows in the older 

 rocks upon which they had been lying ; the basins in which they are 

 now found are bounded by steep walls, sometimes a buried fault- 

 face, sometimes a very steep fold, and are entirely closed. During 



