184 PROCEEDINGS OF THE ACADEMY OF [1888. 



resulting from storms and other disturbances, naturally affects the 

 precipitations about to take place, by accelerating or retarding them, 

 or even redissolviug some of the layers already in situ. In some 

 cases where the Anhydrithut was never formed, the bar not having 

 retained its original height long enough, the salt- clay plays the 

 part of protecting covering ; however, even under these circumstances 

 the resulting series of deposits are so characterised as to point clearly 

 to their mode of origin. 



Salt beds deposited from aqueous solutions under the above-named 

 conditions, are found in all geological epochs as far back as the 

 Archaean rocks ; this is shown by the super-position of Silurian strata 

 to the salt in Salt Range in India. The existence of primitive salt 

 beds points conclusively to the presence of shores, i. e., terra firman 

 at the time of formation. At the present day the first of the above 

 stated agents is found in operation in several localities on the East 

 coast of the Caspian, especially in the great bay of Adschi Darja, 

 whose narrow mouth, Karaboghaz (" black abyss "), is partially cut 

 off from the Caspian by a bar. The bay is one of the saltiest of this 

 inland sea, and receives no supplies of water at all from the land, 

 only its evaporation being balanced by a corresponding influx of 

 sea-water. Under these circumstances no animal can live in the 

 Adschi Darja Avaters, and the bottom is covered with a layer of salt 

 of unknown thickness ; in a specimen of this dej5osit dredged up by 

 Abich, the latter found gypsum intermixed with rock-salt. C. 

 Schmidt* in 1876, found no trace of potassium in the salt bed of 

 Karaboghaz. On the other hand the Avater contained in 100 parts : — 

 8"33 sodium chloride 

 I'OO potassium chloride 

 12"94 magnesium chloride 

 •02 magnesium bromide 

 6'19 magnesium sulphate, etc., 

 in all 28*50 per cent, of salts ; this composition is nearly identical 

 with that found by Usiglio in mother-liquors, when they give off no 

 more water at the ordinary temperature. Similar conditions have 

 been noticed at Tjuk-Karagan, Mertwy-Kultuk and Karassee, Kras- 

 norvodosk, etc. The Caspian then gives up its chloride of sodium 

 to the salt-pans on its east coast and in return receives only mother- 

 liquors, accounting for the character of the water in the principal ba- 

 sin, which contains less salt than the ocean, but much more magne- 



* J. Roth, Chem. Geol. I, 467. 



