THEIR FORMATION. 153 



liigli. But in stating this, we have not given the 

 reader any idea of its vast proportions ; for it is 

 well known that all icebergs, or masses of ice, have 

 a much greater proportion of their bulk under than 

 above water in other words, they sink very deep. 

 The relative proportion that sinks depends on the 

 nature of the ice. Of some kinds, there is usually 

 ten times as much below as there is above water ; of 

 other kinds, there may be eight or five parts below. 

 In all cases there is much more below than above ; 

 so that a mountain of a hundred feet high if 

 afloat may be safely calculated to be a mass of ice 

 not far short of a thousand feet thick. 



As these bergs float southward with the currents, 

 they melt very rapidly. The heat of the sun and 

 the action of the waves gradually round off the 

 sharp angles and topple down the spires that char- 

 acterized them in the land of their birth. The 

 process of dissolution, too, is carried on internally ; 

 for rain and melted water on the surface percolates 

 through the mass, rendering it porous. As the 

 waves cut away the base, the centre of gravity is 

 thrown out, and the whole berg turns over with a 

 terrible crash. Sometimes loud reports like cannon- 

 shots are heard, and the huge mountain splits 

 asunder; while, not unfrequently, the whole berg 

 Mis into a heap of chaotic ruins, and floats away 

 in a mass of smaller pieces which disappear gradually 

 in their parent sea. 



The formation of icebergs has, as we have 



