THE DESICCATION OF AFRICA. 1 43 



On the east, from the Zambesi to Abyssinia, there is a 

 great stretch of very high ground traversed by rift-faults of 

 such recent date that they cut across and interrupt the rivers, 

 the courses of which had already been laid down. Here there 

 is a portion of the country to which the ordinary laws of 

 erosion and river development cannot be applied, and we must 

 leave this area out of consideration. Many of the lakes m 

 this area, indeed, have no outlet and all the drainage from 

 the country adjoining is absorbed in the basins lying in the 

 rift valleys. Lakes Tanganyika and Kivu have been tapped 

 by the Congo and Victoria, Albert, and Albert Edward 

 Nyanzas by the Nile. Lakes Rudolf and Stephanie are 

 drainless, and in the south. Lake Nyasa is drained by the 

 Shire. In Cape Colony, the volcanic lavas of the Drakensberg 

 have been thrown across the drainage from the main watershed 

 of the country and the upper courses have been turned and 

 the waters forced across this watershed as the Orange River. 

 The original lower courses of these rivers, the Bashee, 

 Umzimvubu, Umzimkulu and so on, run impetuously down 

 the steep slopes of the Drakensberg and straight to the sea. 

 So great is the velocity of the water flowing on such a steep 

 and so short an incline, that the erosion is very intense, and 

 these rivers on the coast side of the Drakensberg are eating 

 back into the mountains and are in reality trying to restore 

 the original water-parting. In Abyssina similar features are 

 exhibited ; the short coastal rivers are pitted against the inland 

 system, which, whether flowing into the Nile or Congo, have 

 to traverse the whole length and breadth of the continent, or 

 whether draining into basins without outlet, have far less 

 precipitous courses and consequently erode or wear down their 

 beds far less rapidly. In far future ages the original water- 

 parting will be restored, but the faulted mass is so broad that 

 at present we cannot recognise the plan as we can in the 

 Drakensberg. Africa is a great fault-block which has risen 

 recently, speaking in a geological sense, from the sea, much 

 as an iceberg rises when the top burden melts. The continent 

 of Africa is different entirely from the other continents, which 

 have as predominant features folded mountains. The folds, 

 contemporary with the African faults, form, as it were, two 

 concentric ripples round the fault block of Africa, the nearest 

 ripple being the Alps-Himalayan chain of folds of Europe 

 and Asia and the further ripple being the Aleutian Islands- 

 Rocky. Mountains-Andean chain of America. All the waters, 

 then, run from high tablelands, which, owing to the limited 

 time of exposure to the effects of river erosion, have not been 

 carved into the hills and valleys of the more familiar scenery 

 of Europe; the topography is said to be immature. The 

 rivers run in deep gorges separated by wide tablelands, and 

 they flow rapidly to the sea with water- falls or cataracts in 



