154 GLACIERS THEIR AGE : 



said, puzzled mankind for many years. Their 

 existence has long been known : for, even before 

 men dared to venture their lives in the polar 

 regions, navigators, in crossing the Atlantic Ocean, 

 frequently met with these marble-like mountains ; 

 and, what is worse, sometimes ran at full speed 

 against them, and were sunk with all on board. 

 Bergs _ are frequently enveloped in dense fogs, 

 caused by the cold atmosphere by which they are 

 surrounded condensing the moisture of the warmer 

 atmosphere which they encounter on their voyage 

 southward; hence they are exceedingly dangerous 

 to navigation. But now to speak of their 

 formation. 



Many of the great valleys of the far north are 

 completely filled up with solid ice. Observe, we do 

 not say that they are merely covered over with ice ; 

 they are absolutely filled up with it from top to 

 bottom. Those ice-masses are known by the name of 

 glaciers ; and they are found in most of the elevated 

 regions of the Earth, on the Alps and the moun- 

 tains of Norway, for instance, but they exist in 

 greater abundance about the poles than elsewhere. 



Glaciers never melt. They have existed for un- 

 known ages, probably since the world began ; and 

 they will, in all likelihood, continue to exist until 

 the world comes to an end, at least until the 

 present economy of the world terminates. They 

 began with the first fall of snow, and as falls of 

 snow during the long winters of the polar regions 



