On the Origin of Salt and Salt Lakes. 131} 



contain. The geological revolutions shifting at successive 

 times the waters of the ocean from their bed, have laid dry €^, 

 portion of the sediments, leaving behind a part of the se$^j-. 

 water to be evaporated, thus impregnating the strata with it€}, 

 saline ingredients. Thus we find, that all the marine deposits, 

 however far removed at present from any ocean, contain an 

 appreciable quantity of sea-salt. The amount of salt in th|9» 

 ocean, if spread over the dry land, would form a si^aituia 

 several feet thick over the whole surface. 



Professor Rogers considers, that all salt basins must have 

 been Caspians, seas without outlets, where the dissolved salts 

 have been stored up ; all such seas are more or less saline. 

 As the Caspian Sea is eighty-three feet below the level of 

 the Atlantic, it may be said of this that it is the salt of the 

 Atlantic, shut off in this basin by some surface change, and 

 gradually having become very salt from concentration in a 

 contracting basin. But this cannot explain the occurrence 

 of salt lakes several thousand feet above the sea level. He 

 thinks the formation of these salt lakes depends on the laws 

 of climatology. In those zones of the earth's surface, where 

 the evaporation is greater than the fall of rain, and in those 

 only, we find such saline lakes. In the west of Europe, the 

 fall of rain is greater than the evaporation ; in the east the 

 opposite is true ; in the latter we find salt lakes and basins. 

 In South America, there is a prevailing wind from east to 

 west, the moisture of which is stopped by the Andes, on 

 whose western side, in Peru and Chili, hardly any rain falls ; 

 amid this excessive evaporation we find salt lakes. In the 

 southern region of South America, the prevailing wind is 

 from west to east; its moisture is also stopped by the Andes, 

 but by the western slope ; hence, on the east, we have the 

 arid plains of Southern Patagonia, where are also found salt 

 lakes. The same may be noticed in California. The con- 

 stant drainage of circumjacent districts has been bringing 

 into insulated basins fresh accessions of saline matter dis- 

 solved or leached away from the strata over which they flow, 

 while the evaporation under an arid climate, carrying off* the 

 surplus water, and preventing its flowing on into the general 

 ocean, has been the means of accumulating in these recep- 



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