Vol. 65.] THE KARROO SYSTEM IN NORTHERN RHODESIA. 413 



a red pathway through the green verdure of the slopes until they 

 come to rest, broken into fragments, on the foothills. After the 

 opening rains of the wet season rock-slides are numerous, and 

 remain as noticeable landmarks from a great distance. 



The southern wall of the Luano plain presents a great contrast 

 with that just described. While the Machinga keeps to the one 

 line, and, as will be shown later, is due to a far-extending fault 

 that brings the Karroo beds into contact with the complex, the 

 enclosing mountains on the south side are much worn and bear 

 evidence of submission to prolonged erosion. The main Luano is 

 joined by a number of tributary valleys such as the Formoshi, 

 Mwapula, etc., that run back in broad tongues with Karroo floors, 

 divided one from the other by spurs or promontories reaching out 

 from the plateau-level, and dying away into and under the Karroo 

 plain. Further, the slopes on this side are less steep : they follow 

 no set type as the Machinga does, but roll back in waves, foothills, 

 and creeks, before the uplands are reached, 2 or 3 miles away. 



The apex of the Luano wedge is bifurcated, as it were, by the 

 Lupoposhwe promontory. On its north is the Kalobi Valley (which 

 is also penetrated by a minor promontory, or narrow sloping hog's- 

 back, known as the Matakula Pass) lying along the foot of the 

 Machinga escarpment, while on the south is the beautiful Muchinda 

 Valley. The promontory is the dome of an eastward-pitching 

 anticline of Archaean rocks, which has been covered by Karroo beds, 

 since removed ; while the Muchinda Valley is a syncline rolled 

 out towards the west, containing sediments of Karroo age. It is 

 probable that the other valleys along the southern side of the Luano 

 are of the same structure, gradually rising up to nearly plateau- 

 level, as the folds died out westwards. The evidence regarding 

 the Muchinda will be dealt with later (p. 431) ; it may be here said 

 that masses of the basal conglomerate of the Karroo System occur 

 high up the mountain-limbs on either side, while vestigial pebbles 

 ■of the same beds exist nearly at the head of the valley. 



Archaean inliers of considerable area arise from the clastic floors. 

 Although the Lupoposhwe range dies down into the flat, it continues 

 as an anticlinal dome of gneiss in the centre of the Luano Valley, 

 with Karroo beds on each side, and connects with Kalilingoma 

 Mountain. This is an inlier of Archaean rocks, covering an area 

 of 25 square miles, and rising to about 3000 feet ; that is, not 

 quite to plateau-level. It is much incised, and is completely 

 surrounded by the later sediments, which are tilted round it. 

 Another inlier is Kasafa, connecting with the Lucheri range, 

 forming a chain of metamorphic rocks parallel with the axis of 

 the valley, and extending for some 15 miles. Its summit rises to 

 1286 feet above the valley, or 2540 feet above sea-level — but still 

 ■considerably less than the valley-walls, from which both Kasafa 

 and Kalilingoma are easily overlooked. 



Kasafa also rises from a sea of Karroo sediments. It is opposite 

 the gorge of the Lusenfwa from the northern scarp, which river, 



