THE GREAT ICE AGE 361 



from farther north. One or other supposition is required to 

 account for the appearances, which may be explained on either 

 view. The European hills may have been higher and colder, 

 and changes of level elsewhere may have combined with this to 

 give a cold climate with moisture; or a great submergence 

 may have left the hills as islands, and may have so reduced the 

 temperature by the influx of arctic currents and ice, as to 

 enable the Alpine glaciers to descend to the level of the sea. 

 Now, we have evidence of such submergence in the beds of 

 sea-shells and travelled boulders scattered over Europe, while 

 we also have evidence of contemporaneous glaciers, in their 

 traces on the hills of Wales and Scotland and elsewhere, where 

 they do not now occur. 



I have long maintained that in America all the observed 

 facts imply a climate no colder than that which would have 

 resulted from the subsidence which we know to have occurred 

 in the temperate latitudes in the Pleistocene period, and 

 though I would not desire to speak so positively about Europe, 

 I confess to a strong impression that the same is the case there, 

 and that the casing of glacier ice imagined by many geologists, 

 as well as the various hypotheses which have been devised to 

 account for it, and to avoid the mechanical, meteorological, and 

 astronomical difficulties attending it, are alike gratuitous and 

 chimerical, as not being at all required to account for observed 

 facts, and being contradictory, when carefully considered, to 

 known physical laws as well as geological phenomena.^ 



Carrying with me a knowledge of the phenomena of the 

 glacial drift as they exist in North America, and of the modern 

 ice drift on its shores, I was continually asking myself the 

 question — To what extent do the phenomena of glacier drift 

 and erosion resemble these ? and standing on the moraine of 

 the Bosson glacier, which struck me as more like boulder clay 



^ Canadian Naturalist^ vols. viii. and ix. Geological Magazine, Decern 

 ber, 1865. 



