Vol. 65.] THE KARROO SYSTEM IN NORTHERN RHODESIA. 433 



of quartzite, Chasonsa quartzites, and schorlaceous quartz. These 

 contrast sharply with the dolomite upon which they rest. 



This suggests some explanation of the course of other rivers 

 from the southern plateau in valleys that are rocky defiles near the 

 source, but afterwards descend in wide and open Karroo valleys. 

 Compare the Lukasashi, Mwapula, Formoshi, and Kalobi, and the 

 Losito and Intanga. 



Parallel with the strike of the Muchinda are other folds, but of 

 anticlines, such as the Formoshi divide ; a small dome appearing 

 in the flat, called Impala Ridge ; and a low ridge near TJmkwemba's 

 village that extends for 5 miles, until it joins the big Kalilingoma 

 Mountain. 



At Chisalisali the beds dip away from the Archaean inlier, and 

 also on the south-western spur of the Kalilingoma range; in 

 the Mpupa Creek the shales dip north-westwards off the schists ; 

 and off the north-western side of Kalilingoma the sandstones 

 dip tangentially away. The folds run in the same direction as the 

 axis of the Luano Valley. 



For another region of palpable folding — but, in this case, nearly 

 at right angles to the strike of the gneiss — we can go to the 

 Lufua Eiver where it enters the Karroo area (fig. 3, p. 416 ; fig. 6, 

 p. 431 ; & PI. XXII). Here are three parallel but small trough- 

 valleys of Karroo beds, separated by two ridges of Archaean rock 

 through both of which the river passeis by ' poorts ' or gorges 

 200 feet deep. The first basin, the Malembi Valley, is about a 

 mile and a quarter long by 800 yards wide, and the Karroo beds 

 comprise a basal conglomerate on the north-western hill-slope, 

 and a succession of coal-seams up to Upper Matobola Beds. 

 The second basin, or Katonda, is wider and longer. The north- 

 western limb shows coal-seams lying directly upon the pre-Karroo 

 complex, followed by the Upper Matobola Beds, dipping 32° south- 

 eastwards — a total thickness of 2000 feet. Across this flat the 

 Lufua meanders, and passes through another anticlinal dome to 

 the great Bonda plains of the Zambesi. 



In this vicinity the pre-Karroo movements that gave a direction 

 to the cleavage of the schists, and the axes of certain folds and 

 cleavage, resulted in a north-west and south-east strike ; and this 

 direction is followed by all the rivers and by the Inyanga range 

 (see fig. 3, p. 416). 



The general arrangement of the Karroo strata is that they lie 

 in synclinal basins. South of the Kafue is the wide mid-Zambesi 

 basin : on its northern shores the beds are involved in the minor 

 folds described, and then have a general southerly dip. But in 

 that direction, and before the opposite limb rises up the Matabeleland 

 plateau, there is evidence of other anticlinal arches at Wankie, 

 the Sijarira Hills, the Lubu Gorge, etc., and the downthrow to the 

 north by the Deka Fault. It may, therefore, be said that the mid- 

 Zambesi area of Karroo is made up of a series of folds — the whole 

 forming a great synclinal depression. 



