POLAR IGK' FIELDS. 101 



Every year tlie cold currents flowing from Baffin's 

 Bay (which in strictness should be called a sea) visit 

 Newfoundland with their imposing freight of ice- 

 fields and frozen mountains. On approaching that 

 isLiud they encounter the Gulf Stream, and the 

 frozen masses gradually disappear, being eaten away 

 by the waters, the heat of which undermines them. 

 The earth and fragments of rock which they carry fall 

 to the bottom of the sea. 



Every year the warmer current of the Gulf Stream 

 arrests these masses of ice at the same point of their 

 track, and causes them to break up and disappear. 

 A simple current of water opposes to them an im- 

 passable barrier. The debris accumulates year after 

 year in the neighbourhood of Newfoundland with(jut 

 ever entering into the Mexican current. What ages 

 must it have required for this submarine deposit to 

 have filled up an abyss to a height of from 20,000 to 

 30,000 feet! 



Thus the influence of the polar ice-fields is so 

 great as to modify, in course of time, the form of the 

 earth's surface. This too occurs over a large ex- 

 tent of the globe, seeing that the ice in the northern 

 hemisphere actually attains to the 40th degree of 

 latitude, and in the southern hemisphere to the 

 30th degree. 



