224 



The Mediterranean Sea 



A similar phenomenon is witnessed at the other end of the 

 sea. Here the fresher waters of the Black Sea rush in through 

 the narrow channel of the Dardanelles, causing a surface 

 flow of comparatively fresh water, while there is an outflow 

 below of denser Mediterranean water. The dimensions of the 

 Straits are too small to make the phenomenon of any importance 

 for the supply of the Mediterranean. The conditions both in 

 the Dardanelles and in the Bosphorus were examined very 



carefully in the year 1872 by Captain Wharton, R.N., of 

 H.M.S. "Shearwater," and his results are published in an 

 interesting report to the Admiralty of that date. It is remark- 

 able that the comparatively fresh water of the Black Sea 

 persists without sensible mixture through the Sea of Marmora 

 and into the Dardanelles, while there is constantly a current 

 of Mediterranean water running underneath, and the depth 

 in the two channels is only from 30 to 50 fathoms. There can 

 be little doubt that the saltness of the Black Sea is due wholly 

 to the return current of Mediterranean water entering through 

 the Bosphorus. Were the exit of the Black Sea a channel with 

 sufficient fall to bring the surface of the Sea of Marmora below 

 the level of the highest part of its bottom, so that no return 

 current could take place, the waters of the Black Sea would 

 be fresh. 



