26 



THE OCEAN. 



sheets of water, urged by the billows or the tide into the same basin- 

 of evaporation, disappear likewise, forming new layers of cr3^stals ; 

 it is thus that real banks of a considerable thickness are gradually 

 formed on the borders of the sea, as well as on the shores of inland 

 seas and salt lakes.* 



Even the Black Sea, where the proportion of salt is relatively very 



Fig. 10. — Salt Marshes of Bessarabia. 



inconsiderable, is, on the greater part of its shores, bordered with 

 these natural salt marshes. In Bessarabia, to the south of Odessa, 

 three " limans " of a total area of many square miles, cease 

 in summer to receive their affluents of fresh water, and all the 

 water which has been brought there in winter, evaporates, leav- 

 ing an incrustation of salt; towards the centre of the basins of 

 crystallization the solid mass attains nearly an inch in thickness. 

 In 1826, these natural deposits, worked by the natives, produced 

 about 120 thousand tons of pure salt.f In most of the popul- 

 ous countries of Western Europe, man has converted these casual 



* See in Vol. I. the section .entitle(J,.Z«>?:^s. 

 t Bischof, Lehrhmh der chemischen und physikalischen Geohgie. 



