380 



ICEBERGS. 



[Ch. XVI. 



C* 



thickness, that the weight was conjectured to be from 50,000 

 to 100,000 tons. S] 



ecimens 



among them were granite, gneiss 



mica-schist, clay-slate 

 granular felspar, and greenstone. Such bergs must be of 

 great magnitude ; because the mass of ice below the level of 

 the water is about eight times greater than that above. 

 Wherever thev are dissolved, it is evident that the ' moraine ' 



mar 



to the bottom of th< 

 valleys, mountains, 



platforms 



may 



over with gravel, sand, mud, and scattered blocks of foreign 

 rock, of a nature perfectly dissimilar from all in the vicinity, 

 and which may have been transported across unfathomable 

 abysses. If the bergs happen to melt in still water, so that the 

 earthy and stony materials may fall tranquilly to the bottom, 

 the deposit will probably be unstratified, like the terminal 

 moraine of a glacier ; but whenever the materials are under 

 the influence of a current of water as they fall, they will be 

 sorted and arranged according to their relative weight and 

 size, and therefore more or less perfectly stratified. 



We have already stated that some ice-islands have been 

 known to drift from Baffin's Bay to the latitude of the 

 Azores, and from the South Pole to the immediate neighbour- 

 hood of the Cape of Good Hope, so that the area over which 

 the effects of moving ice may be experienced, comprehends 



a large portion of the globe. 



We learn from Yon Buch that the most southern point on 

 the continent of Europe at which a glacier comes down to the 



Norway, in lat. 67° N 



Mr 



that they extend to the sea, in South America, in latitudes more 

 than 20° nearer the equator than in Europe. Thus in Chili, for 

 example, they occur, as before stated, in the Gulf of Penas, 

 in the latitude of central France ; and in Sir George Eyre's 

 Sound, in the latitude of Paris, they give origin to icebergs, 

 which were seen in 1834 carrying angular pieces of granite, 

 and stranding them in fiords, where the shores were composed 

 of clay-slate. f A certain proportion, however, of the ice- 

 islands seen floating both in the northern and southern hemi- 

 spheres, are probably not generated by glaciers, but rather by 

 the accumulation of coast-ice. When the sea freezes at the 



* Travels in Norway. 



f Darwin's Journal, p. 283 



dl 



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 ice 



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