172 THE DESICCATION OF AFRICA. 



wounding several others which escaped. With man helping 

 to clear away the obstructions, the draining of Ngami by the 

 Zambesi became accelerated. Hundreds of similar examples 

 might be quoted from Cape Colony, many of which I have 

 seen myself; a swamp, either of reeds or palmiet, is burnt 

 in the dry season and in a very few years there is produced 

 a dry valley, down which the flood waters rush during the 

 rains, leaving no portion held in reserve in the swamp, that, 

 like a sponge, had previously retained it. 



The Chobe Swamp has been driven away from the 

 eastern side of the Ngami depression here, but a portion of 

 the Chobe water, together with some from the Okavango, 

 reaches the far side to form the Mababe Swamp. The 

 north-eastern continuation of this is the Komane River, which 

 apparently no longer connects with the Zambesi, if it exists 

 at all at the present day as a river bed. It was crossed by 

 Chapman in 1852 and has not been seen since. 



The Zambesi enters the Ngami depression by the 

 Mpandwe Falls and leaves it at Kasungula, where the Chobe 

 joins the Zambesi, some 50 miles above the Victoria Falls. 

 Between these two points the river follows the north-eastern 

 border of the depression. When the lip of the Victoria Falls 

 was a few feet higher, the whole of the Ngami depression 

 was a vast lake, 300 miles long, from south-west to north- 

 east, and 100 miles broad, having the appearance of a 

 rift-valley lake, like Nyaso and Tanganyika, which are 350 

 and 235 miles long respectively. At a still earlier stage, the 

 Victoria Falls formed an unsurmountable barrier for the 

 Zambesi and its waters went into and filled up the entire 

 Ngami depression. This lake was tapped by the Zambesi 

 below the Falls, eating back by head-stream erosion, just as 

 Tanganyika has been tapped by the Lukuga in quite recent 

 times; in a few centuries Tanganyika will be drained dry by 

 the Lukuga and its basin will present the same appearance 

 as the Ngami depression now does. 



Livingstone's description of the country is as follows 

 t" Missionary Travels," p. 527): — 



The level of the lower portion of the Lekone is about 

 200 feet above the Zambesi at the Falls and considerably 

 more than the altitude of Linyanti ; consequently, when 

 the river flowed along this ancient bed, instead of through 

 the rent, the whole country between this and the ridge, 

 beyond Andara westwards. Lake Ngami and the Zouga 

 (Botletle) southwards, and eastwards beyond Nchokotsa, 

 was one large fresh water lake. The whole of this space 

 is paved with a bed of tufa, more or less soft according 

 as it is covered with soil or left exposed to atmospheric 

 influences. Whenever ant-eaters make deep holes in this 



