130 WALKS AND TALKS. 



XXIII. THK CRYSTALS OK THE SKA. 



SALT AND GYPSUM. 



LOOK over a map of the Caspian Sea and notice on the 

 eastern side a roundish bay nearly cut off from the main 

 body. This is the Karaboghaz or Black Gulf. Though ap- 

 pearing so small, this bay is about ninety miles across. The 

 channel which connects it with the Caspian is only one hun- 

 dred and fifty yards broad and five feet in depth. The water 

 is shallow, though that in the central part of the Caspian 

 attains a depth of twenty-four hundred feet. Through 

 the strait connecting the Karaboghaz with the sea, a current 

 of water sets out from the Caspian at the rate of three miles 

 an hour. The inhabitants of the region fancy that an under- 

 ground passage exists from the Karaboghaz to the Persian 

 Gulf or the Aral Sea. This, however, is impossible, since the 

 Caspian is eighty-four feet lower than the ocean, and one 

 hundred and seventeen (some assert 250) feet lower than the 

 Aral. The vast volume of water discharged into the Kara- 

 boghaz is lost by evaporation from its surface. No large 

 rivers empty into it, while the climate is dry, and the summer 

 intensely hot. 



The water of the Caspian, as you know, is salt. It has 

 been calculated that three hundred and fifty thousand tons of 

 salt are carried by the current into the Karaboghaz daily. 

 The process of evaporation must consequently increase the 

 saltness of the water in the bay ; and the great drain from the 

 sea must tend to diminish its saltness. Now, as a fact, the 

 Caspian possesses only about half the saltness of the open 

 ocean, while the Karaboghaz has become so intensely salt that 

 the animals which once inhabited its waters have disappeared. 

 In fact, the concentration has gone so far that layers of salt 

 are being deposited on the mud at the bottom. In all prob- 

 ability these processes will continue in the future, and it must 

 be anticipated that the salt deposit will increase in thickness 

 as long as this gulf exists. Should there be an elevation of 

 the strait connecting the gulf with the sea, the gulf would 



