136 SCIENCE IN SHORT CHAPTERS. 



I am quite at a loss to understand the reasoning upon 

 which. Mr. Geikie bases his firm conviction respecting the 

 depth of the ice-sheet on the low grounds of Scotland and 

 Scandinavia. He seems to assume that the glaciers of the 

 great ice age had little or no superficial down slope corre- 

 sponding to the inclination of the base on which they rested. 

 I have considerable hesitation in attributing this assump- 

 tion to Mr. Geikie, and would rather suppose that I have 

 misunderstood him, as it is a conclusion so completely re- 

 futed by all we know of glacier phenomena and the physi- 

 cal laws concerned in their production; but the passages I 

 have quoted, and several others, are explicit and decided. 



Those geologists who contend for the former existence 

 of a great polar ice-cap radiating outwards and spreading 

 into the temperate zones, might adopt this mode of measur- 

 ing its thickness, but Mr. Geikie rejects this hypothesis, 

 and shows by his map of " The Principal Lines of Glacial 

 Erosion in Sweden, Norway, and Finland," that the glacia- 

 tiou of the extreme north of Europe proceeded from south 

 to north; that the ice was formed on land, and proceeded 

 seawards in all directions. 



I may add to this testimony that presented by the North 

 Cape, Sverholt, Nordkyn, and the rest of the magnificent 

 precipitous headlands that constitute the characteristic fea- 

 ture of the arctic-face of Europe. They stand forth de- 

 fiantly as a phalanx of giant heralds proclaiming aloud the 

 fallacy of this idea of southward glacial radiation; and in 

 concurrence with the structure and striation of the great 

 glacier troughs that lie between them, and the planed table- 

 land at their summits, they establish the fact that during 

 the greatest glaciation of the glacial epoch the ice-streams 

 were formed on land and flowed out to sea, just as they 

 now do at Greenland, or other parts of the world where the 

 snow line touches or nearly approaches the level of the sea. 



All such streams must have followed the slope of the 

 hill-sides upon which they rested and down which they 

 flowed, and thus the upper limits of glaciation afford no 

 measure whatever of the thickness of "the ice upon "the 

 low grounds of Scotland," or of any other glaciated country. 

 As an example, I may refer to Mont Blanc. In climbing 



