6o THE HISTORY OF THE NORTH ATLANTIC 



unexampled elsewhere in the world, throwing every spring an 

 immense quantity of ice into the North Adantic, and more 

 especially into its western part. On the other hand, he might 

 learn from the driftage of weed and the colour of the water, 

 that the -present great continuous extension and form of the . 

 American continent tend to throw northward a powerful branch 

 of the equatorial current, which, revolving around the North 

 Atlantic, counteracts the great flow of ice which otherwise 

 would condemn it to a perpetual winter. 



Further, such an observer would not fail to notice that the 

 ridges which lie along the edges of the oceans and the ebul- 

 litions of igneous matter which proceed, or have proceeded 

 from them, are consequences of the settling downward of the 

 great oceanic depressions, a settling ever intensified by their 

 receiving more and more of deposit on their surfaces ; and 

 that this squeezing upward of the borders of these depressions 

 into folds has been followed or alternated with elevations and 

 depressions without any such folding, and proceeding from 

 other causes. On the whole, it would be apparent that these 

 actions are more vigorous now at the margins of the Pacific 

 area, while the Atlantic is backed by very old foldings, or by 

 plains and slopes from which it has, so to speak, dried away 

 without any internal movement. Thus it would appear that 

 the Pacific is the great centre of earth-movement, while the 

 Atlantic trench is the more potent regulator of temperature, 

 and the ocean most likely to be severely affected in this respect 

 by small changes of its neighbouring land. Last of all, an 

 observer, such as I have supposed, would see that the oceans 

 are the producers of moisture and the conveyors of heat to the 

 northern regions of the world, and that in this respect and in 

 the immense condensation and delivery of ice at its north end, 

 the Atlantic is by far the more active, though the smaller of 

 the two. 



So much could be learned by an extra-mundane observer ; 





