194 MR. G. W. LAMPLTJGH ON THE [May I907, 



or Linyanti River with the Zambezi, 50 miles west of the Victoria 

 Falls, where Livingstone records the occurrence of amygdaloidal 

 trap * ; while Aurel Schultz notes the presence of ' volcanic rocks ' 

 along the Chobe above the junction. 2 Above the Linyanti flats the 

 Zambezi in its long and tortuous south-easterly course, for a distance 

 of 75 miles, flows in many places over a rocky bed and is broken 

 by numerous rapids ; and, according to Livingstone, 



' the rapids are caused by rocks of dark-brown trap, or of hardened sandstone, 

 stretching across the stream.' 3 



The river is then confined within a shallow rocky gorge for several 

 miles, at the head of which are the Gonye Falls, 20 to 50 feet 

 high, according to the season. Livingstone's account of the geology 

 of this place is as follows : — 



' The rocks of Gonye are reddish grey sandstone, nearly horizontal, and 

 perforated by madrepores, the holes showing the course of the insect in 

 different directions. The rock itself has been impregnated with iron, and 

 that hardened, forms a glaze on the surface — an appearance common to many 

 of the rocks of this country.' 4 



Serpa Pinto, however, describes the rocks of this locality (near 

 Sioma) as ' basaltic strata .... forming natural ramparts, ever 

 running east and west ' ; and he found similar rocks above the Gonye 

 up to the edge of the Lialui flats 5 ; beyond which, for an interminable 

 distance, the solid rocks are entirely concealed beneath the sands 

 and loams of the plateau. The apparent discrepancy between the 

 two accounts may, I think, be that Livingstone's description refers 

 to a capping of the * surface-quartzite ' (see p. 198), beneath which 

 the rock is probably basalt. At any rate, there can be no doubt 

 that the Batoka Basalts extend westward across the Zambezi in 

 some portion, if not in the whole, of its course between the Lialui 

 Flats and the Linyanti Flats. Beyond the river, there is no hope 

 of tracing the basalts, as the whole country for some hundreds of 

 miles — right up to the western edge of the plateau — is a sandy 

 plain over which several travellers have passed without seeing a 

 single stone. 



Southward, as I have previously shown, the basalts may be 

 followed along the outer margin of the Zambezi basin until they 

 disappear under the sands of the Kalahari Desert, where the 

 conditions are analogous to those on the western plains. Somewhere 

 in the northern part of the desert, Chapman during his earlier 

 hunting trips reached two solitary conical hills of * ironstone,' — the 



1 ' Missionary Travels & Eesearches in South Africa ' 1857, chap, xiii, p. 233. 



2 * The New Africa ' 1897, map. 



3 ' Missionary Travels & Researches in South Africa' 1857, chap, xiii, p. 238. 



4 Ibid. chap, xxv, p. 498. 



5 ' How I crossed Africa ' English transl. vol. ii (1881) p. 83. Serpa Pinto's 

 descriptions of the trench of the main river below the Glonye Falls, and of the 

 minor trenches of its rejuvenated tributaries, are interesting, as showing a 

 repetition of some of the characteristics of the Batoka Gorge on a small scale. 

 The physiographical problems raised by the presence of this gorge so far within 

 the plateau-country are too wide to be discussed in this paper. 



