Professor Schtvarz — Earth-movements, S. Africa. 547 



Beds begins. This system stretches certainly from the mouth of the 

 Bushman's River to Worcester, a distance of 400 miles, in an east and 

 west direction, although the direction of the faults in the various fault- 

 pits varies owing to the original grain of the country which was deter- 

 mined when the mountains were folded; thus the Bushman's River fault 

 along which the lower course of the river is cut is W.N.W.-E.S.E. 

 The general arrangements of the series of fault-pits and their dominant 

 marginal faults is east and west. The interruptions of the fault- 

 troughs, which convert what are in all characteristics rift-valleys 

 into a series of isolated pits, are always in a N.E.-S.W. direction, 

 that is, in the direction of the faulted coastline of the eastern corner of 

 South Africa and its accompanying trough in the sea close inshore. 

 The E.-AV. direction is that of the second and larger trough (Fig. 2, B) 

 which also tails out here, but proceeds a little further west than the 

 other, so it is to this fault-trough that the truncated end of South 

 Africa owes its origin. The fault-pits in which the Uitenhage strata 

 lie are due, therefore, to the crossing of two systems of faults, or rather 

 are marginal shearing fractures of two great fault-troughs whicli are 

 directed respectively E.-W. andJS". E.-S.W. It is necessary, however, 

 to establish that the E.-W. trough in the sea is a rift-valley. If we 

 admit that the trough A is a fault-trough, which does not seem to 

 admit of doubt, as we see one side of it actually above sea-level in 

 Pondoland with Upper Cretaceous rocks against it, then the N.E.-S. W. 

 fractures of the fault-pits with the Lower Cretaceous rocks against 

 them are connected with it in the same way as the smaller trough- 

 faults of Egypt are connected with the larger one of the Red Sea. 

 The E.-W. fractures, which form the other two sides of the fault- 

 pits, parallel to the E.-W. trough B, would also be connected with 

 a fault-trough, and thus from their association with the other fractures 

 make it highly probable that this second trough is a rift-valley beneath 

 the sea. 



I have said that Madagascar is a horst of the Colorado plateau type 

 with strike a little east of north. If there are E.-W. rift-valleys, 

 there ought to be horsts of the same nature as Madagascar with this 

 strike. In Schott's map of the Indian Ocean accompanying Chun's 

 Aus den Tiefen des Welt-Meeres, Jena, 1900, these E.-W. horsts are 

 very clearly demarcated. From the south northwards, there is, first, 

 two blocks extended east and west with straight sides, on Avhich the 

 Prince Edward and Crozet Islands lie, then the Rodriquez bank, and 

 then the Seychelles bank. Corresponding to these there are straight- 

 edged banks running IST.-S. : first, that on which the Laccadive, 

 Maldive, and Chagos Archipelago stand, then the banks of Say a de 

 Malha and Albatros Island, north of Mauritius, and far to the south 

 the bank on which Kerguelen and Heard Island stand ; the last, 

 however, trends west of north at about the same angle as Madagascar 

 does east of north. All these submerged plateaux from their nature 

 appear to claim to be parts of the fi'agmented Indo-African continent, 

 and faults that left them standing while the rest of this part of the 

 earth's crust sank were probably contemporaneous with those that 

 affected the southern portions of Cape Colony. The only doubt that 

 can be thrown upon this contemporaneity is due to the fact that the 



