XVIII THE CRATERS OF THE RIFT VALLEY 231 
plateaus fall abruptly to the lake : some of the cliffs 
are several thousand feet high. The lake is 2,700 feet 
above sea-level and forms an abrupt termination to the 
southern end of the western arm of the Rift Valley. 
Gregory has drawn attention to a point of some 
interest in regard to Tanganyika : the natives of 
Ujiji have a folk-lore that goes back to the time when 
the lake was formed by the flooding of a fertile 
valley. 
In regard to the Red Sea some curious folk-lore is 
available, for the Somalis believe that when their 
ancestors crossed from Arabia, to Africa, there was a 
land connection across the Straits of Bab-el-mandeb. 
Fischer demonstrated the existence of the Rift 
Valley in Equatorial Africa (1883). Joseph Thomson 
explored the parts of the valley around Lake Baringo 
(1883), and Count Teleki, accompanied by Lieutenant 
von Hohnel, travelling along the eastern extension of 
the Rift in 1887-8, discovered Lakes Rudolf and 
Stefanie (the latter has since dried up), as well as an 
active volcano at the south end of Lake Rudolf. 
Gregory investigated the portion of the valley which 
traverses the British East Africa Protectorate in 
1892-3, especially from the geological point of view, 
and ascended Mount Kenia. He admirably sums up 
the matter:—From the Lebanons almost to the Cape 
there runs a valley, unique, on account of the per¬ 
sistence with which it maintains its trough-like form 
throughout the whole of its course of 4,000 miles, and 
on account of the fact that scattered’ along its floor is a 
series of over thirty lakes, of which only one has an out¬ 
let to the sea. 
The section of the Rift valley bordered by the Kikuyu 
and the Mau escarpments has a width of about twenty 
miles. The floor of the valley in the neighbourhood of 
Lake Naivasha is 6,300 feet above sea-level. The edge 
of the Kikuyu escarpment is 1,400 feet above the floor 
of the valley and that of Mau is 8,300 feet above sea- 
