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THE DESICCATION OF AFRICA. l8l 



whilst it is not so definitely stated in the paper before us, it is 

 clear from Professor Schwarz's prelim,inary remarks in the 

 newspapers that he claims that in the Karroo, within 

 historic times — that is, within the period of the last few 

 generations — climatic agricultural conditions were vastly more 

 favourable in the past than they are now, and he claims 

 that his scheme will restore to the Karroo those favour- 

 able conditions, and it is mainly on the question of the beneficial 

 results to be derived from the scheme that the greatest exception 

 was taken to Professor Schwarz's proposal. It is, in the first 

 place, denied that, within what could possibly be described as 

 recent times, the Karroo, or any other portion of arid South 

 Africa south of the Molopo, was anything but a pronouncedly 

 arid stretch oi country. The very name " Karroo " is, it is 

 understood, the Bushman or Hottentot word implying aridity. 

 It is true that, during the past few generations, the Karroo, to a 

 large extent, has suffered greatly as a result of erosion, which is 

 due entirely to artificial causes ; but, wliilst this erosion or slooting 

 has been responsible for the most widespread drying up of 

 vleis, etc., and whilst the destruction of mountain vegetation by 

 fires and overgrazing has given rise to destructive floods, which 

 'have eroded large areas of land, and rendered other large areas 

 useless by covering them with sand, boulders and detritus, and 

 in many cases the rate of run-off of the rainfall has been 

 increased to an extent wholly prejudicial to the country, there is 

 no evidence whatever, during the whole of this period, that the 

 rainfall over the Union or its intensity has been decreased, or 

 that meteorological conditions, in general, have altered to a 

 greater extent than is shown by possible periodic variations due 

 to causes at present impenfectly understood, and which cannot 

 be properly analysed with the comparatively short record at our 

 disposal. All the evidence at our disposal goes to show that arid 

 South Africa has been arid for ages which can only be measured 

 in geological time. 



Taking, in the first place, the botanical evidence, we have, 

 in arid South Africa, what I believe to be an unique flora 

 composed largely of succulent and other species which have been 

 adapted by nature to be extremely drought-resisting. It is well 

 known to any observer of such things that this peculiar vegeta- 

 tion, which may be called Karroo vegetation, is unable to exist 

 under more humid climatic conditions. Along the edges of the 

 arid belt, where the rainfall begins to be more regular and 

 greater in amount, but where these better conditions are not fully 

 established, the Karoo vegetation has to put up a very severe 

 struggle for existence, and two or three favourable rainfall 

 years are sufficient to drive it out altogether. 



If Karroo veld is irrigated, the Karoo vegetation is almost 

 immediately killed, and, if such irrigation is stopped, the re- 

 establishment of Karroo vegetation takes place very slowly from 

 the margin. It is obvious that a vegetation so unique in the 

 world and with such pronounced characteristics, has not come 



