208 



ISLAND LIFE 



PAET 1 



about the same time Scandinavia, the Alps, and the 

 Pyrenees received a similar increase of altitude ; and that, 

 almost simultaneously, Eastern North America, the Sierra 

 Nevada of California, the Caucasus, Lebanon, the southern 

 mountains of Spain, the Atlas range, and the Himalayas, 

 were each some thousands of feet higher than they are 

 now ; for all these mountains present us with indications 

 of a recent extension of their glaciers, in superficial phe- 

 nomena so similar to those which occur in our own country 

 and in Western Europe, that we cannot suppose them to 

 belong to a different epoch. Such a supposition is 

 rendered more difficult by the general concurrence of 

 scientific testimony to a partial submergence during the 

 glacial epoch, not only in all parts of Britain, but in North 

 America, Scandinavia, and, as shown by the wide extension 

 of the drift, in Northern Europe ; and when to this we add 

 the difficulty of understanding how any probable addition 

 to the altitude of our islands could have brought about 

 the extreme amount of glaciation which they certainly 

 underwent, and when, further, we know that a phase of 

 very high excentricity did occur at a period which is 

 generally admitted to agree well with physical evidence of 

 the time elapsed since the cold passed away, there seems 

 no sufficient reason why such an agency should be 

 ignored. 



No doubt a prejudice has been excited against it in the 

 minds of many geologists, by its being thought to lead 

 necessarily to frequently recurring glacial epochs through- 

 out all geological time. But I have here endeavoured to 

 show that this is not a necessary consequence of the theory, 

 because a concurrence of favourable geographical con- 

 ditions is essential to the initiation of a glaciation, which 

 when once initiated has a tendency to maintain itself 

 throughout the varying phases of precession occurring 

 during a period of high excentricity. When, however, 

 geographical conditions favour warm Arctic climates — as 

 it has been shown they have done throughout the larger 

 portion of geological time — then changes of excentricity, to 

 however great an extent, have no tendency to bring about 

 a state of glaciation, because warm oceanic currents have a 



