78 SPRINGS— BUSHMEN. Chap. IV. 



some are covered thickly with shells. These shells are identical 

 with those of the mollusca of Lake Ngami and the Zouga. There 

 are three varieties — spiral, univalve, and bivalve. 



In every salt-pan in the country there is a spring of water on 

 one side. I can remember no exception to this rule. The water 

 of these springs is brackish, and contains the nitrate of soda. In 

 one instance there are two springs, and one more saltish than the 

 other. If this supply came from beds of rock salt the water would 

 not be drinkable, as it generally is, and in some instances, where 

 the salt contained in the pan in winch these springs appear has 

 been removed by human agency, no fresh deposit occurs. It is 

 therefore probable that these deposits of salt are the remains of 

 the very slightly brackish lakes of antiquity, large portions of 

 which must have been dried out in the general desiccation. We 

 see an instance in Lake Ngami, which when low becomes brackish, 

 and this view seems supported by the fact that the largest quan- 

 tities of salt have been found in the deepest hollows or lowest 

 valleys, winch have no outlet or outgoing gorge ; and a fountain, 

 about tliirty miles south of the Bamangwato — the temperature of 

 winch is upwards of 100° — while strongly impregnated with pure 

 salt, being on a ilat part of the country, is accompanied by no 

 deposit. 



When these deposits occur hi a flat tufaceous country like the 

 present, a large space is devoid of vegetation, on account of the 

 nitrates dissolving the tufa, and keeping it in a state unfavourable 

 to the growth of plants. 



We found a great number of wells in tins tufa. A place called 

 Matlomagan-yana, or the " Links," is quite a chain of these never- 

 failing springs. As they occasionally become full in seasons when 

 no rain falls, and resemble somewhat in this respect the rivers we 

 have already mentioned, it is probable they receive some water 

 by percolation from the river system in the country beyond. 

 Among these links we found many families of Bushmen ; and, 

 unlike those on the plains of the Kalahari, who are generally of 

 short stature and light-yellow colour, these were tall strapping 

 fellows, of dark complexion. Heat alone does not produce black- 

 ness of skin, but heat with moisture seems to insure the deepest 

 hue. 



One of these Bushmen, named Shobo, consented to be our 



