Vol. 65.] KARROO SYSTEM IN NORTHERN RHODESIA. 



431 



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Archaean inliers or anticlinal^domes, and are probably due to the 



fracturing of the folds, by which the strata are thrown down in steps. 



The tracing of the lines of the basal conglomerate leads to the 



recognition of certain important folds that 



uj j ^ / materially affect the structure of the country, 



11 and offer an explanation of the deep Luano 



5 Mk Valley. 



The Muchinda syncline has already been 

 mentioned, and its northern limb described. 

 On the other side, the conglomerates of the 

 southern limb occur at the Umbelangwe, and 

 along this range the beds dip northwards. 

 Viewed from the front, both walls (the Lupo- 

 poshwe and the Changala) seem to tower up 

 into the sky ; but, if we stand on the strike of 

 the basal beds, it is to find that the foothills 

 slope I7g°, and that the conglomerate dips at 

 10°, while a slope of 13° would carry the bed 

 right up to the summit of the anticline towards 

 the Gyuni. The last-named angle would climb 

 any other part of the plateau- walls, if taken 

 \\ % If/ from the outcrop or contact — which is generally 



now some distance from the range proper, owing 

 to the erosion of the transverse strike-valleys 

 that were commenced while the lower parts of 

 the mountains, at present bare, were protected 

 by the conglomerate. On the Gyuni side of 

 the Lupoposhwe dome 8|° would be all that 

 is necessary. It is easy to forget that these 

 mountains are really of small measurement in 

 comparison with the distance of their summits, 

 and it is of great importance that the explorer's 

 sections should be drawn to the same vertical 

 and horizontal scale if we are to appreciate the 

 mountain-building effects of low dips. 



The Muchinda syncline is gradually ' rolled 

 out ' towards the west, where the undulations 

 ] 1 ili die out on the Hat plateau-level. This has the 



effect of bringing the Archaean floor up to the 

 level of its limbs, and, conversely, deepens 

 the deposits on it, towards the east. The 

 Muchinda River follows the middle of the 

 trough ; its source is in the faintest depression 

 on the plateau, 3700 feet, gradually deepening 

 its valley until, at 12 miles, it is turned at 

 right angles by the hill of Ohilikutulu (altitude 

 3470 feet). On the summit of this are typical blocks, boulders 

 measuring 18 inches in longest diameter, and shingle in profusion. 

 The polish is gone, but they are cupped and dimpled, and consist 



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