198 T. F. Jamieson — Inland Seas of the Glacial Period. 



A submarine ridge extends across from Cape Spartel to Cape 

 Trafalgar,' over which the deepest soundings do not exceed 167 

 fathoms. Now it is computed that the amount of evaporation over 

 the whole drainage area of the Mediterranean basin is fully double 

 that of the precipitation — the average rainfall being about 30 inches 

 in the year, while the evaporation is considered to exceed 60 inches ; ^ 

 so that, were it not for the strong current which sets into it from the 

 Atlantic, the level of this inland sea could not be maintained at its 

 present height. The excess of evaporation is further shown by the 

 fact that the waters of the Mediterranean are Salter than those of 

 the Atlantic. 



If therefore the communication between the two seas were cut off 

 by a barrier of dry land extending across the Straits, then the 

 Mediterranean would sink gradually in level until an equilibrium 

 was established between the loss and the supply. 



We have seen that in the history of the salt lakes of North 

 America the two periods of high-water were separated by one of 

 great dryness, during which the Utah lake was dried up altogether ; 

 and there is much evidence to prove that in Europe the Glacial 

 period was broken up by at least one long interval of warmer 

 temperature, during which the Hippopotamus and other African 

 animals found their way north as far as England. In Germany 

 also they have recently got further evidence that a dry climate 

 supervened in Central Europe after the first stage of the Glacial 

 period, the remains of several 'steppe' animals having been dis- 

 covered by Dr. Nehring^ in an intermediate part of the drift beds, 

 while many of the Loess deposits have been shown by Kichthofen 

 to be accumulations formed by dry winds, such as occur only under 

 climatic conditions of great aridity.^ 



Supposing, then, the Atlantic to be shut out by the conversion of 

 the Straits of Gibraltar into dry land, and the climate to be such as 

 to induce a strong evaporation from the surface of the Mediter- 

 ranean, its waters would of necessity sink in level, and it would be 

 converted into a chain of lakes. The submarine ridge which exists 

 between Sicily and Tunis would be laid dry, and another path 

 would thus be opened up for the passage of the African animals 

 into Europe. And here it is interesting to note that remains of the 

 African Elephant have been found in the caves of Sicily along with 

 those of the Hygena and Hippopotamus. In Malta also the relics of 

 a mammalian fauna are got which can be accounted for only on the 

 supposition that this small island was formerly of much greater 

 extent and connected probably with the mainland. 



Admiral Spratt says the abundance of the remains of Hippo- 

 potamus that have accumulated in the caves of Malta lying over 

 the bold coast-line of that island, as also in the caverns over the 

 north shore of Sicily, seems to point to the necessary existence of 



1 Lyell's Principles, llth ed. vol. i. p. 497. 



^ Encycl. Britannica, 9th ed. art. " Mediterranean." 



^ See Geological Magazine for 1879, p. 176, and Ibid, for Feb. 1883, p. 51. 



^ Credner, Elemente der Geologie, 5th ed. p. 272. 



