48 THE TANGANYIKA PROBLEM. 



eastern faces of these islands are steep, precipitous cliffs, com- 

 posed of somewhat metamorphosed sandstones, which have 

 been worn out at their bases into caves by the great ocean- 

 like surf of the lake. On the western side these islands 

 slope less steeply into the lake, and from their crests can 

 be seen, over an expanse of deep blue water, 25 miles 

 away, the gigantic scarps of the main western coast- 

 line of Tanganyika. Soundings in the open water, between 

 the islands of Kinyamkolo and the great western scarps, 

 showed great depths, 200 fathoms and upwards being 

 encountered ; but not far from the abrupt west coast, 

 some distance north of Mbeti, there is a submerged plat- 

 form, which rises slightly, like the islands, from west to 

 east, and terminates in that direction in a submerged cliff, 

 its relation to the main western scarps being shown in 

 Diagram facing p. 44. 



Passing still westward over the western scarps, we find 

 them to be composed of massive quartzites, sandstones, 

 conglomerate and shales, 2,000 feet and more being 

 exposed along the main western coast-line of the lake, 

 and, finally, having ascended the magnificent red and 

 yellow precipices which these exposures form, we reach a 

 table-land, but one which has everywhere a slight dip to 

 the west, and we are now, as a matter of fact, on the long 

 main western slope of the whole continental mass. Through 

 the contemplation of the above facts relating to the structure 

 of the Great Central Range in the region of the south end 

 of Lake Tanganyika, it will have become apparent that 

 the phenomena presented by the crest of the ridge are here 

 more complex than in the region of Nyassa, although it 

 will, at the same time, have also become obvious that these 

 phenomena are precisely similar in kind. The complexity 

 in this region is due, in fact,' simply to the existence of a 



