﻿232 MESSES. A. R. ANDREW AND T. E. G. BAILEY [May IQIO, 



plateau-regions lying round the Victoria Falls of the Zambezi. 1 

 The other plateaux are far more uneven in character, and more 

 closely resemble the elevated tracts of the South-West of England, 

 such, for instance, as the granite platform of Dartmoor. 



The Nyika and Vipya Plateaux. 



The Nyika is a small but lofty platform of gneiss and granite 

 covered with weathered soil. It rises in its central portions to 

 7000 aod 8000 feet above sea-level. At its best, the plateau is 

 distinctly undulating, and granite hills or tors are numerous towards 

 the centre. The drainage is more or less radial, but the main rivers 

 run southwards. These rivers have reached maturity on the central 

 highlands, but become rejuvenated along the plateau-edge and cut 

 back into it for a considerable distance in deep V-shaped valleys. 

 The source of the Northern Iiukuru lies on the top of the plateau. 

 The Nyika portion is of senile character, and flows in a south- 

 westerly direction. On reaching the plateau-edge it drops in a 

 fine fall and cascades to a depth of 100 feet or so, and then turns 

 sharply round and flows for some miles northwards in a deep V- 

 shaped valley. It affords an excellent example of a hanging valley. 

 Hanging valleys of this type are not uncommon in Nyasaland, but 

 no instance of a typical hanging corrie has been noticed. This, of 

 course, is due to the fact that even the highest plateaux have escaped 

 glaciation. The hanging valley of the Upper llukuru has evidently 

 been formed by the rapid cutting-back of the main river, probably 

 along a north-and-south line of fault, beheading as it went an old 

 plateau-river flowing southwards. 



The plateau-edges, both on the north and on the south, have been 

 carved out into mountain -peaks and ranges; but portions of the 

 western and eastern margins are sharply defined, and drop steeply 

 and for some thousands of feet into the valleys of the Northern and 

 Southern Rukuru respectively. These sharply-defined edges coincide, 

 as we have seen, with long lines of fault, separating the Karroo 

 sediments from the older crystalline rocks. 



The Vipya plateau lies to the east and south of the Nyika, and 

 forms a long narrow strip, perhaps 80 miles long and some 10 to 30 

 miles broad. Its northern portion is divided off from the Nyika 

 by the wide trough of the Henga Valley, floored on the north with 

 rocks of Karroo age. The eastern edge of the plateau is usually 

 steep, and drops in vaguely defined steps right down to the lake- 

 shore. The lake lies at a height of 1645 feet above sea-level, 

 while the Vipya plateau reaches a heigh*- of over 7000 feet in places, 

 so that the drop is considerable. The Vipya is somewhat lower than 

 the Nyika, and less of the old plateau scenery is preserved. On the 

 whole, however, the two plateaux are closely comparable, and were 

 doubtless at one time continuous. It is obvious that the flattening 

 of these platforms must have preceded the formation of the deep 



1 G-. W. Lamplugh, ' Greology of the Zambezi Basin round the Batoka Gorge * 

 Quart. Journ. Geol. Soc. vol. lxiii (1907) p. 162. 



