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 CHAPTER II 



CLASSIFICATION AND DESCRIPTION OF ICE 



Ice met at sea consists for the most part either of icebergs originat- 

 ing from glacier and continental ice sheets, or of sea ice formed by the 

 freezing of the top layers of the sea itself. Sea ice proper accounts 

 for probably 95 percent of the area of ice encountered at sea, but bergs 

 are important because of the manner in which they drift far from 

 their place of origin, constituting grave menaces to navigation. A 

 certain amount of ice may also originate in rivei*s or estuaries as fresh- 

 water ice, but it is already in a state of decay by the time it reaches 

 the open sea and its importance is no more than local. 



With some risk of over-simplification, figure 5 outlines the re- 

 lationships between the chief categories of ice, and gives an indication 

 of the cycles of formation and disintegration. 



Land ;cf 



WATER VAPOR 



1 



SNOW 



I 



hfEVE 



1 



ICE CAP 



GLACIERS SHELF ICE 



( Ani arc t ,c only) 



FAST ICE- 



Sca let 



SEA WATER 



I 



SLUSH 



\ 



PANCAKES 



i 



/YOUNG ICE 



I 



-►PACK ICE^ 



/ 



^ARCTIC PACK 



I ( Arc tic on ly 1 



PALEOCRYSTIC ICE 



/ (Arct ic only ) 



■ ICEBERGS HUMMOCKS< 



i 1 



BERGY BITS 



1 



FIELDS 



FLOEBERGS FLOES 

 ^ORIS 



GLACONS 



GROWLERS 



BRASH 



: i 



7 SEA WATER 



WATER VAPOR 



Figure 5. — Synoptic diagram showing the general relationships between the various kinds 



of ice occurring in the sea. 



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