ANOTHER POSSIBLE CAUSE OF THE GLACIAL EPOCH. 159 



The author carefully refers to the sources of information in the 

 different parts of the subject of his paper. 



Mr. Waeeen Upham, A.m., F.G.S.A., writes : — 



St. Paul, Minnesota. 



January 8/tZ, 1898. 



The explanation of the climatic changes and ice acciimulations 

 of the Glacial epoch presented in Professor Hull's paper, with its 

 accompanying map, seems to me a most valuable addition to our 

 understanding of this very exceptional and unique geological 

 epoch. There can be no doubt that the epeirogenic uplifting of 

 the lands on each side of the North Atlantic Ocean produced 

 important changes of the Gulf Stream and of its influence on the 

 climate of Europe. The lowering of the temperature of that great 

 sea current may well have been a chief element in the causation of 

 the Ice Age in the British Isles and Northern Europe, supple- 

 menting the effect due to the greatly increased altitude of the 

 land, of which the fjords bear testimony. 



In North America, howevei', where our storms and waves of 

 varying bai'ometric pressure and temperature sweep from west to 

 east and north-east across the country, thence passing over the 

 North Atlantic, we must, I think, ascribe the chief part in the 

 production of the Glacial epoch to the high elevation of the land, 

 probably 3,000 to 5,000 feet above its preglacial and its present 

 height. 



Professor Hull's map might indeed well be coloui'ed farther into 

 the present sea ai-ea between Europe and Greenland, to the sub- 

 marine contour of 450 or 500 fathoms, as for the Blake plateau of 

 America. If the preglacial uplift of the sea bed between the 

 Atlantic and Arctic oceans was so great, which is very probable 

 these oceans were completely separated by land, and the Gulf 

 Stream and warm superficial oceanic drift from it were wholly 

 excluded from contact with Scandinavia. That condition, in 

 combination with the high land uplift, gives an ample explanation 

 of the origin of the Ice Age in Europe, which seems to have been 

 essentially contemporaneous with that of North America. 



The Rev. R. Ashington Bulled, B.A., F.G.S., writes: — 



There can be but one opinion about the interest and importance 



N 2 



