364 THE GREAT ICE AGE 



be capped with perpetual snow, and through a great part of the 

 year surrounded with heavy field and barrier ice, and that in 

 those hills there might be glaciers of greater or less extent. 

 Further, it should be understood that I regard the boulder 

 clays of the St. Lawrence valley as of different ages, ranging^ 

 from those of the early Pleistocene to that now forming in the 

 Gulf of St. Lawrence; and that during these periods great 

 changes of level occurred. Further, that this boulder clay 

 shows in every place where I have been able to examine it, 

 evidence of subaqueous accumulation, in the presence of 

 -marine shells or in the un weathered state of the rocks and 

 minerals enclosed in it; conditions which, in my view, preclude 

 any reference of it to glacier action, "except possibly in some 

 cases to that of glaciers stretching from the land over the mar- 

 gin of the sea, and forming under water a deposit equivalent 

 in character to the boue glaciare of the bottom of the Swiss 

 glaciers. But such a deposit must have been local, and would 

 not be easily distinguishable from the marine boulder clay. It 

 is of some interest to compare Canadian deposits with those of 

 Scotland,^ which in character and relations so closely resemble 

 those of Canada ; but I confess several of the facts lead me to 

 infer that much of what has been regarded as of subaerial 

 origin in that country must really be marine, though whether 

 deposited by icebergs or by the fronts of glaciers terminating 

 in the sea, I do not pretend to determine.^ It must, however, 

 be observed that the antecedent probability of a glaciated con- 

 dition is much greater in the case of Scotland than in that of 

 Canada, from the high northern latitude of the former, its 

 hilly and maritime character, and the fact that its present 



^ Journal of Geological Society. Papers by Jamieson, Bryce, Crosskey, 

 and Geikie. 



'■^ Geikie, Trans. Royal Society of Edin. Geikie assigns a more compli- 

 cated structure than appears to be present in Canada ; but there are Cana- 

 dian equivalents of the principal glacial periods which he assumes. 



