E. H. L. Sch'ioarz — Plains in Cape Colony. 187 



for building purposes. I am busy collecting material from 

 these sea-beaches, but the process is a slow one, as in most 

 cases the shells themselves have been dissolved out leaving 

 only imperfect casts behind, but the evidence so far is that 

 the forms represented belong to living species, though these 

 are now confined to the warmer waters farther north. These 

 sea-beaches extend from 10 feet above sea-level, or actually at 

 sea-level, at Port Elizabeth, and can be followed on the ledges 

 up to 1,300 feet on the Addo Hills ; on the higher ones the 

 calcareous material has all disappeared.* 



Fig. 2. The mouth of the Groot River, Zitzikamrna, Cape Colony, a little 

 east of the spot shown in fig. 1. The coast ledge is revealed at low water; 

 the ledge behind belongs to the 700-foot shelf. The rock is quartzite of the 

 Table Mountain Series : the abrupt change of strike is seen. 



Besides these exposed shelves, there is a submerged one like- 

 wise divided into subsidiary ledges which range from 20 to 

 60 fathoms, the outermost deepest one lying 90 fathoms below 

 the ocean surface. The edge of this plain is called the Agul- 

 has Bank, beyond which is very deep water ; it is a zone of 

 danger to the shipping, as the waves from the Antarctic are 

 broken here and boil and swirl before sending their crests 

 towards the land over the shallower sea-bottom. The edge of 

 the Agulhas plateau continues the southwesterly coast-line -of 

 the eastern side of South Africa to the longitude of Cape 

 Town, and the submerged plain must always be considered as 

 part and parcel of the present continent. Dr. Gilchrist has 

 reported bowlders on this plateau 40 miles from land and this 

 in itself is sufficient evidence of the surface having once been 

 above the sea ; besides this I am unable to conceive of any 

 * Rogers, A. W., Ann. Rept. Geol. Comm., p. 43. Capetown, 1906. 



