Deposition of Salt in the Mediterranean, 225 



Art. VII. Remarks on the Deposition of Salt in the Mediterranean 

 Sea. By the Rev. W. B. Clarke, A.M. F.G.S. &c. 



The question respecting the saltness of the Mediterranean 

 has received an illustration from the introduction of steam- 

 vessels into that sea. It is well known that a constant current 

 sets eastward through the Straits of Gibraltar ; and that a 

 northerly current descends from the Black Sea; and that 

 numerous rivers of great volume, as the Nile, Po, Rhine, 

 &c, flow into the Mediterranean, bringing down various 

 mineral products in a state of chemical solution. Of these, 

 the calcareous and some other detritus are deposited at 

 no great distance from the embouchures of the respective 

 streams, forming banks of stone and sand. The particles of 

 salt, however, cannot be disposed of, by deposition, in exactly 

 the same manner; yet, inasmuch as evaporation on an immense 

 scale goes, on in the Mediterranean from the action of the hot 

 and dry winds of Africa, Asia, &c, unless the current which 

 sets in from the Atlantic be counterbalanced by currents in an 

 opposite direction, large deposits of salt must necessarily take 

 place in the deepest portions of the sea. Experiments have 

 certainly led to the conclusion that there are under currents, 

 as well as lateral currents, westward. But, as a bar stretches 

 across the straits between Capes Trafalgar and Spartel, and 

 the deepest part of the water over it is but 220 fathoms; 

 while, between Gibraltar and Ceuta, the soundings are 950 

 fathoms, Mr. Lyell, in whose Principles of Geology (i. 298.) 

 the reasonings on this subject may be seen, has concluded 

 that there are, probably, basins at the bottom of the Medi- 

 terranean of incalculable depth ; and that precipitations of 

 salt take place " on the grandest scale, continuous masses of 

 fine rock salt extending, perhaps, hundreds of miles," &c. 

 Mr. De la Beche [Geological Manual, p. 98.) doubts this 

 inference ; and says that the theory, " though very ingenious, 

 can scarcely be true," since the bottom of the sea, at the 

 deepest places measured, is not salt, but mud, sand, and 

 shells. Mr. Lyell has, however, mentioned the probability 

 of central abysses unfathomable; and it is there he has placed 

 the deposit he mentions. The objection, therefore, loses much 

 of its force. Analysis proves that the water of the Mediter- 

 ranean, at great depths, does contain more salt than at the 

 surface, by the ratio of 4 to 1. The following table gives 

 the examination of three bottles of water by Dr. Wollas- 

 ton, as given in the Philosophical Transactions, 1829, parti. 

 29.: — 

 Vol. VIII. — No. 48. q 



