ProfefiHor Sclncm'z — Earth-movements, 8. Africa. 545 



escarpment of the Karroo. The beds laid down are richly fossiliferons, 

 and from them Plesiosaurs, Ammonites, Trigonias, and other Lower 

 Cretaceous marine forms have been obtained. These are the Sunday 

 liiver Marine Beds. JN^ow comes a gap in our knowledge. From the 

 Neocomian to the Mio-Pliocene nothing is known in the midlands of 

 South Africa. In the east, in Pondoland, there is a patch of Upper 

 Cretaceous deposits and in Zululand beds of a slightly lower horizon. 

 In both these cases the strata lie against a fault-scarp of much older 

 beds and have therefore been dropped down just as the Uitenhage 

 Beds have been ; in fact, there can be little doubt that the faults in 

 both cases belong to the same system and are very little, if at all, 

 separated in age. This consideration leads one to the conclusion that 

 Lower Cretaceous beds occur beneath the Upper in Pondoland and 

 Zululand, and that consequently the Lower Cretaceous strata in the 

 midlands and west of Cape Colony were followed originally by Upper 

 Cretaceous deposits, which have now, however, been\ entirely removed 

 by denudation. In Madagascar on the west there is a complete 

 conformable series through the Juras and Cretaceous to the Tertiary, 

 and the tilting of these beds westwards connects the beds so tilted 

 with the faulted strata in Cape Colony. 



It should be noted that at this time Madagascar was in all 

 probability joined to the mainland by a land bridge through the 

 Comoro Islands, and in the bay between the island and the mainland 

 the complete conformable series of rocks above-mentioned were laid 

 down. Traces of the upper part of the series is found in Zululand, 

 but the faulting to be described below intervened and cut up the 

 mainland side of the bay. In Madagascar the eastern side is a sharp 

 fault-scarp as shown by the almost straight coastline, but on the 

 w^estern side the beds have been mei'ely tilted. We know from 

 the fault-troughs in Baviaan's Kloof that as a rule the slices of 

 the earth's crust let down in this region are faulted on the side 

 towards the land and bent downwards on the side towards the sea, so 

 on this evidence the deep channel between Madagascar and the 

 mainland is a normal interrupted ti'ough fault or pit of the Baviaan's 

 Kloof type. 



At any rate, we may suppose that after the Sunday River Marine 

 Beds of Uitenhage were laid down, the whole of the southern portion 

 of South Africa was beneath the sea, and beds of sand, mud, and 

 limestone, :iow entirely removed, covered all the country even as far 

 west as Cape Town, and that this deposition went on into the 

 Eocene period. 



At the close of th.e Eocene period, or at least before the Miocene, 

 the old Madagascar ridge became faulted down. The crack or faxilt 

 sliced off the eastern corner of South Africa and spread north w^ards 

 along the Lebombo Mountains, separating the Eastern Transvaal from 

 Portuguese East Africa, then upwards along the Shire Biver to the 

 great western and eastern rift valleys to the Red Sea. On the 

 landward side of the fault the country rose in compensation. 

 Denudation started to work at a rapid rate, removing all the loosely 

 compacted rocks but recently laid down, and would have swept them 

 entirely away but for the fact that there was developed a system 



DECADE V. — VOL. IX. — NO. XH. 35 



