FORMATION OF ICEBERGS. 143 



steady course, it finally reaches many miles beyond 

 the original shore-line. 



And now it has attained the climax of its progress. 



When, long ages ago, after pouring over the sloping 

 land, it finally reached the coast and looked down the 

 bay which it was nltimately to fill up, its fiice was 

 many hundreds of feet high. Gradually it sank below 

 the line of waters as it moved outward, and finally its 

 front has almost wholly disappeared. 



In a former chapter I have mentioned that a block 

 of fresh-water ice floating in sea water rises above the 

 surflice to the extent of one eighth of its Aveight and 

 bulk, while seven eighths of it are below the surface. 

 The cause of this is too well known to need more than 

 a passing explanation. Every school-boy is aware 

 that water, in the act of freezing, expands, and that in 

 the crystal condition fresh water occupies about one 

 tenth more space than when in a fluid state ; and 

 hence, when ice floats in the fresh water from which it 

 was formed, one tenth of it is exposed above, while the 

 remainino; nine tenths are beneath the surface. When 

 this same fresh-water ice (which it will be remembered 

 is the composition of the glacier) is thrown into the 

 sea, the proportion of that above to that below being 

 chano-ed from one and nine to one and seven, is due to 

 the greater density of the sea-water, caused by the 

 salt which it holds in solution. 



Now it will be obvious that, as the glacier continues 

 to press further and further into the sea, the natural 

 equilibrium of the ice must ultimately become dis- 

 turbed, — that is, the end of the glacier is forced fur- 

 ther down into the water than it would be were it 

 free from restraint, and at liberty to float according to 

 the properties acquired by congelation. The moment 



