160 ISLAND LIFE 



PART I 



almost amounting to demonstration, that for all known 

 geological periods our continents and oceans have occupied 

 the same general position they do now, and that no such 

 radical changes in the distribution of sea and land as 

 imagined by way of hypothesis by Sir Charles Lyell, have 

 ever occurred. Such an hypothesis, however, is not with- 

 out its use in our present inquiry, for if we obtain thereby 

 a clear conception of the influence of such great changes 

 on climate, we are the better able to appreciate the tendency 

 of lesser changes such as have undoubtedly often occurred. 



Land as a Barrier to Ocean Currents. — We have seen 

 already the great importance of elevated land to serve as 

 condensers and ice-accumulators ; but there is another and 

 hardly less important effect that may be produced by an 

 extension of land in high latitudes, which is, to act as a 

 barrier to the flow of ocean currents. In the region with 

 which we are more immediately interested it is easy to see 

 how a comparatively slight alteration of land and sea, such 

 as has undoubtedly occurred, would produce an enormous 

 effect on climate. Let us suppose, for instance, that the 

 British Isles again became continental, and that this con- 

 tinental land extended across the Faroe Islands and Iceland 

 to Greenland. The whole of the warm waters of the 

 Atlantic, with the Gulf Stream, would then be shut out 

 from Northern Europe, and the result would almost cer- 

 tainly be that snow would accumulate on the high moun- 

 tains of Scandinavia till they became glaciated to as great 

 an extent as Greenland, and the cold thus produced would 

 react on our own country and cover the Grampians with 

 perpetual snow, like mountains of the same height at even 

 a lower latitude in South America. 



If a similar change were to occur on the opposite side of 

 the Atlantic very different effects would be produced. 

 Suppose, for instance, the east side of Greenland were to 

 sink considerably, while on the west the sea bottom were 

 to rise in Davis' Strait so as to unite Greenland with 

 Baffin's Land, thus stopping altogether the cold Arctic 

 current with its enormous stream of icebergs from the west 

 coast of Greenland. Such a change might cause a great 

 accumulation of ice in the higher polar latitudes, but it 



