150 THE DESICCATION OF LATER GEOLOGICAL TIMES. 



to have been profoundly impressed ^vith the appearances which presented 

 themselves in various localities of a former much greater expansion of the 

 Inke system, both of Central and Southern Central Africa, as the following 

 quotations from his principal volume prove :".... consequently, when the 

 river [Lekone] flowed along this ancient bed, instead of through the rent, 

 the whole country between this, and the ridge beyond Libebe westwards ; 

 Lake Ngami and the Zouga southwards ; and eastwards beyond Nchokotsa, 

 was one large fresh-water lake. There is abundant evidence of the exist- 

 ence and extent of this vast lake in the longitudes indicated, and stretching 



from 17° to 21° S. latitude All the African lakes hitherto di.'^covered 



are shallow, in consequence of being the mere residua of very much larger 

 ancient bodies of water. There can be no doubt that this continent was, 

 in former times, very much more copiously supplied with water than at 



present, but a natural process of drainage has been going on for ages 



Whether this process of desiccation is as rapid throughout the continent, as 

 in a letter to the late Dean Buckland, in 1843, I showed to have been the 

 case in the Bechuana country, it is not for me to say." * 



Livingstone's ideas in regard to the diminution of some of these lakes and 

 the disappearance of others need not here be dwelt upon. Naturally, they 

 are highly catastrophic in character, the idea of a possible diminution of the 

 rain-fall not having occurred to him, although the facts which he furnishes 

 seem very clearly to point in that direction, rather than towards drainage by 

 earthquake fissures and the like events. 



The entire aspect of Southern Africa, as described by recent travellers, is 

 that of a region which has undergone great changes of climate within a 

 recent period. Dryness is pre-eminently its characteristic at the present 

 time; but in tlie whole appearance of the country there is proof — as it 

 appears to the writer — that this dryness has been on the increase since 

 the southern part of the continent acquired its present topography. There 

 has certainly been a great diminution of the water-surface since the Tertiary 

 epoch began. 



A considerable portion of Europe belongs in the same category as North- 

 eastern North America in its relations to the question now before us. The 

 phenomena of desiccation are complicated with those of former glaciation, so 

 that it is not so easy to separate the two classes of facts from each other : 



* Missionary Travels in South Africa. London, 1857, Chapter XXVI., under the heading of " Ancient 

 Lakes." 



