48 Correspondence — Professor E. Hull. 



AlSrOTHEE, POSSIBLE CAUSE OF THE GLACIAL PERIOD. 



Sir. — In the discussion which took place on my paper on 

 " Another Possible Cause of the Glacial Period," read before the 

 Geological Society on December 2, 1896, the only serious objection 

 to it, as it seemed to me, was one by Dr. Blanford, in which he 

 maintained, that the explanation I gave on the basis of Professor 

 Spencer's hypothesis did not account for the extension of the 

 Himalayan glaciers, which extension has been pointed out by 

 Sir J. D. Hooker, and which is, in all probability, referable to 

 the Glacial Epoch. Not having previously considered this point, 

 I was unable at the moment to meet the objection urged by 

 Dr. Blanford ; but I suggested greater elevation of this mountain 

 chain, which would have not only increased the cold, but would 

 have caused greater precipitation of snow at levels on the flanks 

 relatively lower than at present. Further consideration induces 

 me to believe that this is a sufficient explanation, as there are 

 good grounds for believing that such elevation actually took place 

 in the Pliocene Period, continuing into that of the post-Pliocene. 

 It has been made abundantly clear that at this epoch the whole 

 region of the Mediterranean basin underwent considerable elevation, 

 "when this great inland sea was closed against the ocean by the rise 

 of the Straits of Gibraltar into land, and when a chain of lakes 

 connected by rivers was established from the Black Sea throughout. 

 This was the epoch of the great migration of the Mammalia from 

 the Europe-Asian Continent into Africa, and the formation of the 

 causeway, now submerged, between Italy and Tunis. The epoch 

 was one of increasing cold, and affected in the direction of extension 

 downwards the glaciers of the Pyrenees, the Alps, and the Caucasus ; 

 and also gave rise to those of the Lebanon, first determined by the 

 same distinguished traveller to whom I have referred above. Is 

 it not probable — nay, is it not certain, that this great upward move- 

 ment of the crust, in an easterly direction, was continued into the 

 Himalayas, which lie almost in the same general line of upheaval ? 

 What reason have we for supposing that it stopped short anywhere 

 between Syria and the region north of the Ganges? I know of 

 none ; and if this be admitted, Di'. Blan ford's objection falls to the 

 ground ; at least, I wait for reasons to show that this is not the case. 

 I am glad to find that my views are gaining acceptance amongst 

 geologists who were not present at the meeting of the Societ3^ 

 Professor Spencer wrote some time since that he had arrived at 

 similar conclusions (though not published), as the necessary outcome 

 of his own views regarding the uprising of the " Antillean Con- 

 tinent" ; and a few days since I received a letter from Colonel 

 Feilden, F.G.S., in which he says: "I am quite satisfied that your 

 view is correct, that the so-called Glacial Epoch was due to some 

 deflection of the warm current from the Polar Basin. If Professor 

 Spencer is correct (and I have read his papers), the elimination of 

 the Gulf of Mexico would deprive the northern half of the Atlantic 

 of its chief heating apparatus." Edward Hull. 



