68 
THE TANGANYIKA PROBLEM. 
very large part of the interior, most of the region between 
Tanganyika and Nyassa, many districts east of this line to 
the north and to the south, together with huge areas to the 
west, were all portions of a great depression which in many 
places extended across the axis of the Great Central Range. 
At some time or other there w r ere wide, deep waters in 
these regions, so wide and so deep that more than 
three thousand feet of sandstones were quietly laid 
down in them, and, consequently, there was a time 
when the present Central African region was vastly 
different from what it is now.* It may very probably have 
been that portions of this area, the Shiri highlands, some of 
the high granitoid ridges of the Great Central Range, and 
portions of British and German East Africa, were even then 
dry land, but there must unquestionably have been wide 
stretches of open, deep water between whatever land-masses 
existed, and these land-masses in all probability formed a 
group of islands occupying the position of the equatorial 
portion of the continent of to-day. The changes which 
followed were produced by the initial stages in the forma- 
tion of the great central chain. The areas of ancient 
depression in which the Old African sandstones had been 
deposited became disturbed and gradually more and more 
involved with the extension of the folding and the crinkling 
of the earth’s crust alonof axes running north and south, until 
in time their floors were raised up, as we have seen, into part 
of the hog’s back of the modern African peninsula ; the sand- 
stones and conglomerates being, finally, in places folded up 
and broken into the high crests and scarps of the Great 
Central Range as we find it now. 
* It would seem indeed to be indicated that there was at some time an cast and west 
depression of considerable breadth which very possibly separated the northern and 
southern portions of the continent, and connected up the oceans on its east and west 
coasts (see map facing p. 75). 
