198 ISLAND LIFE 



Carolina, which by the Gulf Stream is transferred 20° 

 northwards to our islands, might certainly, under the 

 favourable conditions which prevailed during the Creta- 

 ceous, Eocene, and Miocene periods, have been carried 

 another 20° north to Greenland and Spitzbergen ; and this 

 would bring about exactly the climate indicated by the 

 fossil Arctic vegetation. For it must be remembered that 

 the Arctic summers are, even now, really hotter than ours, 

 and if the winter's cold were abolished and all ice-accumu- 

 lation prevented, the high northern lands would be able to 

 support a far more luxuriant summer vegetation than is 

 possible in our unequal and cloudy climate.^ 



Effect of High Excento^icity on the Warm Polar Climates. — 

 If the explanation of the cause of the glacial epoch given 

 in the last chapter is a correct one, it will, I believe, follow 

 that changes in the amount of excentricity will produce no 

 important alteration of the climates of the temperate and 

 Arctic zones so long as favourable geographical conditions, 

 such as have been now sketched out, render the accumu- 

 lation of ice impossible. The effect of a high excentricity 

 in producing a glacial epoch was shown to be due to the 

 capacity of snow and ice for storing up cold, and its 

 singular power (when in large masses) of preserving itself 

 unmelted under a hot sun by itself causing the inter- 

 position of a protective covering of cloud and vapour. 

 But mobile currents of water have no such power of 



^ The objection has been made, that the long polar night would of itself 

 be fatal to the existence of such a luxuriant vegetation as we know to have 

 existed as far as 80° N. Lat., and that there must have been some altera- 

 tion of the position of the pole, or diminution of the obliquity of the 

 ecliptic, to permit such plants as magnolias and large-leaved maples to 

 flourish. But there appears to be really no valid grounds for such an 

 objection. Not only are numbers of Alpine and Arctic evergreens deeply 

 buried in the snow for many months without injury, but a variety of 

 tropical and sub-tropical plants are preserved in the hot-houses of St. 

 Petersburg and other northern cities, which are closely matted during 

 winter, and are thus exposed to as much darkness as the night of the 

 Arctic regions. We have besides no proof that any of the Arctic trees or 

 large shrubs were evergreens, and the darkness would certainly not be 

 prejudical to deciduous plants. With a suitable temperature there is 

 nothing to prevent a luxuriant vegetation up to the pole, and the long con- 

 tinued day is known to be highly favourable to the development of foliage, 

 which in the same species is larger and better developed in Norway than in 

 the south of England. 



