Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/167

 nessed 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, together 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 still 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 line 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. Everywhere, 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 hollowed 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.

Richard Thornton and others in old raised beaches at Natal, near Inanda, and at the mouth of the Zambesi River.
 * The writer has seen implements of early man which were obtained by