iS. ON THE COKKELATION OF THE KAKHOO SY.STEI\r 



TN RHODESIA. 



I;y A. J. C. MoLVNKix, E.G.S. 



Strata tliat can now clefinitely be correlated with tlie Karroo 

 system of move southern Africa have an extensive and important 

 development in Rhodesia. (»enerally speaking, they occupy the low- 

 lying areas of the 8abi and I^impopo rivers in the south, and of the 

 Zanil)esi in the north. In the formei- direction they ha\e not been 

 found at a greater altitude than I'OOO feet. In the Zambesi basin, on 

 the other hand, they not oidy form the bed of that river from the 

 Gonye Falls (about two hundred miles west of the Victoria Falls) to 

 Tete, but rise up the southern slopes of the basin until they cap the 

 watershed or main axis of the RlK)desian plateau near Bulawayo. 

 There, at Taba'sinduna, is a typical basalt covered table mountain—a 

 landmark for miles around. 



Tills occurrence is made up of the highest members of the Karroo 

 .system, namely, the Forest Sandstone and volcanic beds, and takes the 

 position of an overlap on the eroded surface of the fundamental schists. 

 Bet\\een this escarpment and the margin of the Limpopo area of 

 Karroo beds to the south there is an unco\ered stretch of granites and 

 schist> of some 150 miles broad, sloping at first rapidly, but from 

 Geelong the surface is flat, broken by occasional granite stumps, as at 

 Setoutsi, from some of which the distant Transvaal mountain ranges 

 can be seen across tlie Limpopo plains. 



So far, no outliers of Karroo lieds ha\e been found that could 

 dentite a ctintinuity of the formation from the Zambesi to the Limpopo, 

 or that the intermediate plateau was at any time masked by the 

 Ft>rest Sandstone and Volcanic series. It should be said, ho\ve^•er, 

 that the southern slopes of tlie plateau are much more denuded than 

 the northern, and tiiat while the former are deeply incised and present 

 rugged features, the Zambesi slopes are still protected by tiie porous 

 sands and forest belts that extend continuously over them, and the 

 contours in that direction are, for 150 miles, soft and undulating. 



Evidence is therefore wanting in respect of a general submergence 

 under Karroo sediments, but the broken-oft" dip escarpments of the 

 Taba'sinduna and Pasij^as line, arrested just short of the apex of the 

 country, denotes a further southern extension than now exists. 



Q'he area of Southern Rhodesia is 192,000 square miles, of which 

 about one-fourth is covered by rocks of the Karroo system. The extent 

 of the sedimentary formation is therefore important in the tectonic 

 geology of the country. It covers up a great area of schists which,, 

 where they emerge from their sandy mask, as at Bembesi and Lower 

 Gwelo, contain auriferous veins, but this is more than compensated by 

 the valuable and immeasurable stoiesof coal which the Kairtio beds in 

 Rhodesia contain. 



