SOUTHERN AFRICA. 77 
be less tlian five or six thousand feet. The soil too on all 
sides of tiie Zwart-Kop's salt pan was deep vegetable earth, 
in some places red and in others black, resting upon a bed of 
clay, and without having the smallest vestige of salt in its 
composition. That salt in a soil was inimical to and destruc- 
tive of vegetation was well known to the ancients. In the 
metaphorical manner of the eastern nations in treating things 
as well as ideas, it was usually ordained, after the destruc- 
tion of a city, to " throw salt upon it that nothing afterwards 
might grow there." The shrubbery, however, upon the 
banks of this salt lake was beautifully luxuriant to the very 
water's edge. 
A cause, then, less remote remains to be adopted ; and 
the only conclusion seems to be that either salt-water springs 
must exist towards the center of the lake, or the Avater that 
rests in it must come in contact with a stratum of sal gem or 
rock salt. The latter supposition is perhaps the only satis- 
factory way of accounting for the saltness of the sea ; and if 
the subterranean strata of this substance be among the num- 
ber of those that are most commonly met with in the bowels 
of the earth, as has been supposed, the effects that exist 
may easily be conceived to arise from it. The salt of Poland 
alone would probably be more than sufficient to salify the 
Northern Atlantic. 
We happened to visit the lake at a very unfavorable season, 
when it was full of water. About the middle it was three 
feet deep, but sufficiently clear to perceive several veins of a 
dark ferruginous color intersecting in various directions the 
