FORMER GLACIATION OF SCANDINAVIA DISCUSSED. 371 



reached to Scotland on the west, covered Fudand on the east, and extended 

 to Dresden on the south, woidd be not less than half a million square miles. 

 But this is so large as to entii-ely dwaif the glaciated region of the Alps, so 

 that the latter must be admitted to hold a quite subordinate position as com- 

 pared with the part played by the Scandinavian Ranges during the time of 

 the greatest ice extension. In fact, the most reasonable view to take of the 

 glaciation of Western Europe is that it was one phenomenon, all the higher 

 portions being more or less glaciated in sympathy with the existence of a 

 mass of ice on the exti'eme northwest of the continent covering an area of 

 half a million square miles. 



Many of the interesting topics which are suggested by the brief descrip- 

 tion of the areas of past and present glaciation given in the preceding pages 

 must be left unconsidered. All that concerns us particularly at present, 

 or, at least, all for which space can here be found, is the answering of the 

 question whether the facts presented oblige us to admit that the mean tem- 

 perature of the earth must have been lower than it now is at the time when 

 an ice sheet covered Scandinavia and extended for an indefinite distance 

 over the adjacent continental mass of Europe. 



The first point which may be made in this connection is, that the cause of 

 the phenomena in question must be sought for in changed local conditions, 

 and not general ones or such as must necessarily affect the entire surface of 

 tlie earth, or of one hemisphere even. The fact that the Ural Mountains 

 were not covered with ice, or even glaciated in the slightest degree, while 

 the Scandinavian Range was the centre from which an immense ice sheet 

 extended itself, has an important bearing on the question before us. The 

 absence of traces of a former glaciation in the Ural seems more remarkable, 

 as contrasted with the condition of the Scandinavian Mountains, when we 

 consider that these two chains are at no great distance from each other, that 

 they have about the same position in latitude, nearly the same direction, and 

 that they do not differ very greatly in altitude. In connection with the ab- 

 sence of any marks of a Glacial epoch in the Ural, we have also to take into 

 consideration the fact that the Altai Range presents ns with conditions of 

 an analogous kind, although the last-named chain lies in a somewhat more 

 southern latitude. 



We are furnished with a good opportunity for comparing the conditions 

 requisite for more or less extensive glaciation in three regions which in 

 several important respects closely resemble each other, but which are, and 



