8 (No. 99 GEOGRAPHY 1 between the Welle - Kibali and the Bomokandi rivers, the country is hilly and even mountainous, rising to 3,600 ft. or more at the head -waters of the former river. To the west of the districts just described the country becomes lower and forms a series of broad plateaus more or less uniform in character. North of Niangara the surface is level or gently undulating, with an average elevation of about 2,500 ft. Here there fore the Congo -Nile divide is not a well-defined crest, although the actual water-parting is clearly marked.

To the south and west of Niangara the country retains the same general character but is somewhat lower. Among the hills which rise above the average level of the land are Mount Angba on the Welle near | Amadi, Mount Madjema near Poko, and Mount Tena on the Bomokandi .

In the broad level plains which are characteristic of the greater part of this region the surface features are generally monotonous . The Welle and most of its tributaries wind their way between high banks of clayey alluvium, but the broad basins in which they flow are much too shallow to be termed valleys in the ordinary sense. Numerous rapids prevent continuous naviga tion, and in the intervening reaches, where the fall of the land is slight, the rivers frequently expand during the rainy season into enormous swamps. As a general rule the country north of the Welle is a savanna region, and its open character is therefore in marked contrast to the densely wooded lands in the central basin of the Congo.

Eastern Highlands. — These form the eastern border of the central basin and rise from it to the inner escarp ment of the Western Rift valley. To the north of the Lukuga the mountains of Ugoma run along the northern part of the west coast of Lake Tanganyika. Farther to the north , where they border the Rusizi and Lake Kivu,