133 
of Edinburgh, Session 1869 - 70 . 
Between these two northern depressions lies the deeper and 
narrower valley of the Nile, which contains the Tanganyika and 
Albert Lakes. The beginning of this depression may he said to 
be at Lake Liemba, which lies sunk 2000 feet down in the edge of 
the plateau north of Lake Nyassa; then it opens out into a wider 
valley to the east of Southern Tanganyika, but again closes in the 
northern part of that lake, and is only a little wider where the 
Albert Lake is sunk between the edge called the Blue Mountains 
and the part of the plateau which separates this depression from 
the higher one of the Victoria Nyanza. To south-west of Tan¬ 
ganyika the narrow valley of the Upper Nile appears to have an 
opening into that one which contains the Chambeze and its lakes, 
made known by Livingstone, in the low-lying country of the 
Cazembe. 
This valley of Bangweolo and Moero Lakes seems to be most com¬ 
pletely surrounded on all other sides; by the high plateau of Usango 
eastward, by a narrower portion of it called the Muchinga Moun¬ 
tains southward, and again by the Kone Mountains, and a broader 
part of the plateau, the copper country of Katanga, on the west. 
The only other opening or outlet into this valley is apparently the 
rent in the mountains of Rua, through which the river makes its 
escape to join Ulenge. Westward is another and wider depression 
—the wide high plain which forms the kingdom of the great 
Muata Yanvo, watered by the Kassabi River, and stretching out 
between the Mossamba Mountains where the river rises, and the 
plateau of Katanga, which separates the Yanvo’s from the Cazembe’s 
valley. 
The Zambezi valley closes the Lake Region southward. The 
Zambezi is the exceptional river of Africa, since it breaks through 
the higher side of the plateau to reach the Indian Ocean. Its 
sources, however, seem to be on the inner side of the plateau, 
springing on the western slopes of the Kone Mountains, and flow¬ 
ing first to the south-westward. The vast basin of this river 
(about 568,000 square miles) is comparable to that of the Volga, 
and would make more than one hundred river basins such as that 
of the Thames. 
On the west, the waterparting of the Zambezi valley at Lake 
Diiolo is apparently but little elevated above the plain of the Muata 
VOL. VII. 
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