The southern frontier is formed by the escarpments which separate the Niger basin from those of the coast rivers of Liberia.
From the valleys their rugged, deeply indented escarpments, stretching away to the horizon, have the appearance of a continuous chain of mountains.
The most extensive Scottish escarpments are found among the igneous rocks.
The rocks at the base of the slopes are granite, the upper escarpments are of sedimentary rocks.
On the east the limit of the Uganda Protectorate in 1901 was the thalweg of Lake Rudolf and a line drawn from the south-eastern coast of that lake south along the edge of the Laikipia and Kikuyu escarpments to the frontier of German East Africa.