332 



ANTARCTIC CRUISE. 



and some appear to be formed of a soft and porous ice ; others are 

 quite blue ; others again show a green tint, and are of hard flinty ice. 



"\ 



mm % mum 



Large ice-islands are seen that retain their tabular tops nearly entire 

 until they reach a low latitude, when their dissolution rapidly ensues ; 

 whilst some have lost all resemblance to their original formation, and 

 had evidently been overturned. The process of actually rending 

 asunder was not witnessed by any of the vessels, although in the 

 Flying-Fish, when during fogs they were in close proximity to large 

 ice-islands, they inferred from the loud crashing, and the sudden 

 splashing of the sea on her, that such occurrences had taken place. 

 As the bergs gradually become worn by the abrasion of the sea, they 

 in many cases form large overhanging shelves, about two or three feet 

 above the water, extending out ten or twelve feet ; the under part of 

 this projecting mass exhibits the appearance of a collection of icicles 

 hanging from it. The temperature of the water when among the 

 icebergs, was found below or about the freezing point. 



I have before spoken of the boulders embedded in the icebergs. All 

 those that I had an opportunity of observing, apparently formed a part 

 of the nucleus, and were surrounded by extremely compact ice, so 

 that they appear to be connected with that portion of the ice that 

 would be the last to dissolve, and these boulders would therefore in all 

 probability, be carried to the farthest extent of their range before they 

 were let loose or deposited. 



The ice-islands, on being detached from their original place oi 

 formation by some violent storm, are conveyed to the westward by 

 the southeast winds which are prevalent here, and are found, the first 

 season after their separation, about seventy miles north of the barrier. 

 This was inferred from the observations of both the Vincennes and 

 Porpoise, the greatest number having been found about that distance 

 from the barrier. That these were recently detached is proven by 

 their stratified appearance ; while those at a greater distance had lost 



