XIX THE RIFT VALLEY AND ITS LAKES 251 
increases the specific gravity of the water. Thus, the 
water of the Dead Sea which lies 1300 feet below the 
level of the Mediterranean Sea, contains 25 per cent, of 
solids. The water of Salt Lake, Utah, has about the 
same proportion of solids. Lake Nakuru is in a similar 
condition. Lake Rudolf is probably undergoing a like 
change, due to the prolonged drought which has afiected 
the northern section of the Rift Valley. 
Suda Lakes. There is a deposit of natural soda 
covering an area of thirty square miles, known as Lake 
Magadi, at the southern end of the eastern arm of the 
Rift Valley. The deposit is estimated to contain 
200,000,000 tons of soda ; whenever a portion of the 
surface soda is removed, it is quickly replaced, as though 
it were pushed up from below. Further south in 
German territory there exists another soda lake, known 
as Lake Natron, discovered by Fischer (1883). 
References. 
Moore, J. E. S. ... The'Tanganyika Problem. London, 1903. 
Gregory, J. AV. ... The Great Rift Valley. London, 1896. 
Huxle}^, T. H. ... Hasisadra’s Adventure. Essays on Contro¬ 
verted Questions. London, .1892. 
Hohnel, L. von ... Discovery of Lakes Rudolf and Stefanie. 
Translated by Nancy Bell. 1894. 
Powell-Cotton, P. H. G. In Unknown Africa. London, 1904. 
Smith, A. Donaldson... Through Unknown African Countries. 
London, 1897. 
Neumann, A. H. ... Elephant Hunting in East Equatorial 
Africa. 
