CHAP. IX.] 



MILD AECTIC CLIMATES. 



191 



transfer a large proportion of their heat into the northern and 

 Arctic seas. The heat that they gave out during the passage, 

 instead of being widely dispersed by winds and much of it lost 

 in the higher atmosphere, would directly ameliorate the climate 

 of the continents they passed through, and prevent all accumu- 

 lation of snow except on the loftiest mountains. The formation 

 of ice in the Arctic seas would then be impossible ; and the 

 mild winter climate of the latitude of North Carolina, which 

 by the Gulf Stream is transferred 20° northwards to our islands, 

 might certainly, under the favourable conditions which prevailed 

 during the Cretaceous, 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-accumulation 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 Excmtricity 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 



1 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 

 alteration 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 

 prejudicial 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. 



