II.] GEOGRAPHY. CO 



and at those of Gonye : the immense salt-pans here and there 

 occurring being like residua. He says that when the Zambesi 

 flowed along its ancient bed, the whole country between the 

 lower portion of the Lekone, " and the ridge beyond Libebe 

 westwards; Lake Ngami and the Zonga southwards; and 

 eastwards beyond Nchokotsa, was one large fresh-water lake. 

 There is abundant evidence of the existence and extent of this 

 vast lake in the longitudes indicated, and stretching from 17° 

 to 2.1° south latitude. 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. Wherever ant- 

 eaters make deep holes in this ancient bottom, fresh-water 

 shells are thrown out, identical with those now existing, in the 

 Lake Ngami and the Zambesi. The Barotse valley was another 

 lake of a similar nature, and one existed beyond Masiko, and 

 a fourth near the Orange River. The whole of these lakes 

 were let out by means of cracks or fissures made in the subtend- 

 ing sides, by the upheaval of the country. The fissure made 

 at the Victoria Falls let out the water of this great valley, and 

 left a small patch in what w T as probably its deepest portion, 

 and is now called Lake Ngami. The Falls of Gonye furnished 

 an outlet to the lake of the Barotse valley, and so of the other 

 great lakes of remote times. The Congo also finds its way to 

 the sea through a narrow fissure, and so does the Orange River 

 in the west ; while other rents made in the eastern ridge, as the 

 Victoria Falls and those to the east of Tanganyenka, allowed 

 the central waters to drain eastward. All the African lakes 

 hitherto discovered are shallow, in consequence of being the 

 mere residua of very much larger ancient bodies of water."' 



The form which the rivers have taken in the great valley 

 imparts the idea of a lake slowly drained out; their beds and 

 sides helping to the same conclusion. 



The lakes laid down on the maps are as follows: Taganyika, 

 in the north; Maravi, in the east; Ruena, Lukutu, and Shuia, in 

 the centre; Dilolo towards the west, and Ngami in the south- 

 west- These latter two only have been visited by Europeans. 



