THE GREAT ICE AGE 347 



course of its extension, he has now, like those primitive men 

 who are imagined in the post-glacial age to have followed up 

 the retreat of the ice, the pleasure of seeing the once formid- 

 able continental glacier broken up into great local glaciers 

 on the mountain ranges separated by intervening areas of 

 submergence. 



The questions relating to this subject are too numerous and 

 varied for treatment here. The question of the causes of the 

 great lowering of temperature in the glacial age I shall leave 

 for consideration in the next chapter, and merely state here 

 that I believe changes of distribution of sea and land and of 

 ocean currents are sufficient to account for all the refrigeration 

 of which there is good evidence. I content myself with a 

 comparison of the glacial phenomena of Mont Blanc and of 

 the Gulf of St. Lawrence from my own observation, 1 and some 

 general deductions as to glacier possibilities. 



A scientific voyager carries with him a species of question- 

 ing peculiar to himself. Not content with vacantly gazing 

 at the sea, scrutinizing his fellow passengers, noting the 

 changes of the weather and the length of the day's run, he 

 recognises in the sea one of the great features of the earth, 

 and questions it daily as to its present and its past The 

 present features of the sea include much of surpassing interest, 

 but the questions which relate to its origin and early history 

 are still more attractive. Some of these questions are likely 

 to interest a voyager from Canada entering the Atlantic by 

 one of its greatest tributaries, the St. Lawrence. 



In doing so, we approach the ocean not at a right angle, 

 but along a line only slightly inclined to its western side, and 

 we find ourselves in a broad estuary or trough, having on its 

 north-western side rugged hills of old crystalline rocks, the 

 Laurentian, ridged up in great folds or earth waves parallel 

 to the river. On the south-east or right-hand side we have 

 1 Published in 1867. 



