1870.] GKIESBACH— GEOLOGr OF NATAL. 69 



Bessed so very few changes during the deposition of at least 5000 

 feet thickness of strata, must have lasted through the Triassic age 

 right up to the Upper Jurassic ; as in India the highest of these 

 beds seem to belong to the Jurassic formation. The greater portion 

 of the Indian Ocean must, at this period, have been depressed, to- 

 gether with a large part of India and Southern Africa, which were 

 covered with the shallow Cretaceous sea, having a peculiar fauna of its 

 own. The Cretaceous deposits of Southern India and Africa were all 

 shallow-water and coast-deposits, as is proved by the species of fossils 

 they contain and also by the quantities of wood imbedded in them, which 

 give evidence of a formation on a shallow coast, where the wood was 

 soon covered with sand and mud and in this way preserved. Since 

 that period the coast has been gradually rising, or the sea retiring. The 

 portions of the Cretaceous sea nearest the old coast-line had become 

 dry land; and we see the remains of these deposits in Southern India 

 and Africa. There cannot be the slightest doubt that the upheaval 

 of the country is still going on ; for along the whole coast of South 

 Africa, from the Cape to Durban Bluff, and stiU further north, 

 even as far as Zanzibar, modern raised beaches *, coral-reefs, and 

 oyster-banks may everywhere be seen. At the Izinhluzabalungu 

 Caves is such a point, where the rising of the coast is plainly visible ; 

 recent oyster-banks are now 12 feet and more above high -water 

 mark. The same can be observed on the whole hne of the Natal 

 coast. Vander Decken has observed the same thing at Zanzibar, 

 and is of the same opinion as myself, viz. that the eastern coast is 

 rising. Early in the present year I had the opportunity of observing 

 at the Bazaruto Islands, about 90 miles to the north of Inhambane, 

 on the east coast of Africa, a series of raised coral-reefs round the 

 island of Marsha, containing many living shells and quite recent 

 oyster-banks. In fact, I believe that the Bazaruto Islands only owe 

 their existence to the circumstance that the coral-reefs have been 

 upheaved, and that their surface was naturally covered with loose 

 sea-sand, which is the only soil of these desolate islands. Every- 

 where, at about 12-14 feet depth, water is to be obtained at Marsha ; 

 wherever the sand is removed the coral-rock is reached. 



"What with this constant rising of the land and the consequent 

 shallowing of the river, I do not believe that the Port of Durban 

 has much hope for the future, as some day the entrance to the 

 harbour, which is not very deep at present, must be blocked by a 

 bar across it like most of the African ports. The only exception to 

 this rule is the large Port of Delagoa Bay ; the port is cleared of 

 sand and mud by nature itself. It was evidently formed by the 

 north and south current of Mozambique, which has gradually hol- 

 lowed out this fine bay. Between Elephant Island and the terra 

 firma the current enters the bay, and, turning round in it, returns to 

 the sea between Elephant and Inyack Islands, in this way always 

 keeping the entrance open by its scouring-out action. 



* The writer has seen implements of early man which were obtained by 

 Eiehard Thornton and others in old raised beaches at Natal, near Inanda, and 

 at the mouth of the Zambesi Eiver. 



