CAUSE OF MILD POLAR CLIMATES. 171 



may not have seen in those strata boulders larger than 

 a child's head may be perfectly true, but that there 

 actually are none is a thing utterly incredible. Still 

 more incredible, however, is the conclusion which he 

 draws from this absence of boulders — viz., that from 

 the Silurian down to the termination of the Miocene 

 period no glacial condition of things existed either in 

 Greenland or in Spitzbergen. Both these places are at 

 present in a state of glaciation ; and were it not, as we 

 have seen, for the enormous quantity of heat which is 

 being transferred from the equatorial regions by the 

 Gulf Stream, not only Greenland and Spitzbergen, but 

 the whole of the Arctic regions would be far more 

 under ice than they are. A glacial state of things is 

 the normal condition of polar regions ; and if at any 

 time, as during the Tertiary age, the Arctic regions 

 were free from snow and ice, it could only be in 

 consequence of some peculiar distribution of land and 

 water and other exceptional conditions. That this 

 peculiar combination of circumstances should have 

 existed during the whole of that immense lapse of 

 time between the Silurian and the close of the Tertiary 

 period is certainly improbable in the highest degree. 

 In short, that Greenland during the whole of that time 

 should have been free from snow and ice is as 

 improbable, although perhaps not so physically 

 impossible, as that the interior of that continent 

 should at the present day be free from ice and covered 

 with luxuriant vegetation. Perhaps the same skill 

 and indomitable perseverance which proved the one 

 conclusion to be erroneous may yet one day prove the 

 other to be also equally mistaken. 



Professor Xordenskjold does not appear to believe 

 in alternations of climate even in temperate regions 

 for he says, " from palaeontological science no support, 



