THE TANGANYIKA PROBLEM. 61 



characters which its surrounding mountain masses now pre- 

 sent were first acquired. Half way up Nyassa at Mount 

 Waller, however, we encounter the complete change in the 

 geological character of the country to which I alluded in 

 the preceding chapter, thick sandstone deposits appearing 

 sandwiched in between granitoid hills to the north and 

 south. We in fact here encounter a stratified neck composed 

 of sandstone, quartz ites, conglomerates, and yellow and grey 

 shales which are between two and three thousand feet thick, 

 and stretch completely across the lake from east to west. 

 They have been cut by two chief lines of faulting, which are 

 coincident with the opposing shores of the lake, so that faces 

 of the sandstone and conglomerates, etc., have been raised 

 up into imposing lines of cliffs more than two thousand feet 

 above the lake shore on either side. They extend to the 

 east of Nyassa, but how far in this direction has not, I 

 believe, been hitherto ascertained.* To the west they cer- 

 tainly pass into the Loangwa valley, where similar faulting 

 has been observed, they reappear among the mountains 

 flanking the north of the lake, and they extend along the 

 track of the old Stevenson Road as far as the hills which 

 flank to the north the depression which exists about 

 Fort Hill. These sandstones are often much distorted, 

 often metamorphosed ; and at the north end of Nyassa, 

 between Karonga and Fort Hill, they are greatly tilted 

 and broken, sloping at a high angle out of the bed of 

 the lake. 



The massive sandstones and conglomerates just 



* It appears, however, from Bornhardt's map of the German territory about the 

 north of Lake Nyassa that these deposits actually extend into the great depression 

 of the Rovuma valley ; which in turn stretches directly to the Indian Ocean. Still 

 later, observations have come to hand, which show that similar deposits cover a con- 

 siderable area to the east of Nyassa and extend probably as far south as Pemba on the 

 coast of the Mozambique. 



