Yol. 65.] KARROO SYSTEM IN NORTHERN RHODESIA. 409 



valleys are but faulted-down areas, one might expect to find un- 

 faulted remnants on the uplands. If the reverse be the case, and 

 the coal-measures occur in pre-Karroo valleys as parts of an ancient 

 landscape, search for coal-deposits may be confined to these, or to 

 other valleys of corresponding features. 



Geographically also, the demarcation of deposits so far north 

 that are undoubtedly correlated with the Karroo System of South 

 Africa is of deep interest, for, together with regions in East Africa, 

 they form the link with the Indian provinces of Suess's ancient 

 continent of Gondvvanaland— as the Permo-Carboniferous age of the 

 fossils (many belong to the Glossopteris Flora) conclusively shows. 



It will be seen, then, that an investigation into the distribution 

 of the Karroo strata in trans-Zambesia will involve us in their 

 relationship to surface-features, and require more than passing 

 reference to the folding movements that have influenced so much 

 the geology and topography of these regions. 



II. Physical Features. 



As this paper deals with the relationship of the Karroo strata 

 to the structure, it becomes necessary to describe some of the 

 features of the country. At the outset, however, as I have not 

 visited the Luang wa Valley, and it has so much in common with 

 the parts included in my travels, I must, in introducing my subject, 

 abstract the references of Mr. L. A. Wallace 1 to that locality. 



The Luangwa Valley. 



The Luangwa River rises near Fort Hill, some 40 miles west of 

 the northern end of Lake Nyasa, and runs for a distance of 400 miles 

 in a nearly straight line south-westwards to join the Lukasashi, 

 between high mountain-walls that are really but the incised edges 

 of the plateau. Near its source is the JS"yika plateau of 6000 to 

 7000 feet, where the succession of Archaean rocks, the Mount- 

 Waller Sandstones, and ' Drummond's beds ' has been dealt with by 

 Mr. J. E. S. Moore. 2 The left rampart of the Luangwa is the Nyasa 

 plateau of 4000 feet — the western, known as the Machinga, 3 

 here reaching 5000 feet, being thus higher than its opposite wall. 

 It is notable that Mr. Wallace states that the parts of the valley 

 nearest the source are much more precipitous than those bordering 

 the Lower Luangwa, although the western escarpments are again 

 steeper than the Nyasa side. 



The valley, from 20 to 35 miles in width, has a fiat appearance, 

 with alluvial deposits, and a floor of sandstones and limestones of 



1 ' North-Eastern Khodesia ' Geogr. Journ. vol. xxix (1907) p. 369. 



2 ' The Tanganyika Problem ' London, 1903. 



3 The native meaning of this word is ' fence.' 



