86 A TEXTBOOK OF OCEANOGRAPHY 



The pack-ice, when it breaks up on the approach of summer, 

 spreads out in two main currents into the open ocean, where it 

 speedily melts. Of these two, the East Greenland Current is 

 the more important ; it is estimated to distribute two and a half 

 times the amount of pack-ice to that of the current from Baffin 

 Bay, the West Greenland Current. The area between Spits- 

 bergen and Greenland is always, both summer and winter 

 alike, more or less filled with pack-ice. It is not a continuous 

 layer. The reflection of the sea's surface seen in the sky pro- 

 duces two impressions ; an effulgence near the horizon 

 indicating ice is the so-called ice-blink; open water reflects 

 a dark water-sky. 



The White Sea is filled in winter with a land-floe; east 

 of this the pack-ice boundary runs in winter towards Nova 

 Zembla, most of Barents Sea being fairly open water. The 

 pack-ice boundary in May runs in a curve roughly south-west 

 from Prince Charles's Foreland in Spitsbergen to the north- 

 east coast of Iceland, Jan Mayen Island being within the 

 pack-ice. 



No pack-ice comes out through Bering Strait. In Bering- 

 Sea the pack-ice renews itself every winter, so that in May it 

 practically fills up Bristol Bay, and thence its boundary runs 

 across via St. Matthew Island (Pribilofifs) to the Asiatic coast, 

 which it cuts at about 60 N. Lat. and 170 E. Long. By 

 August the ice has shrunk considerably, and in particular there 

 is a run of more or less open water right round the continental 

 land. 



The west coasts of Spitsbergen and Nova Zembla are almost 

 entirely free from pack-ice in the height of summer, and the 

 lane of water up the west coast of Greenland has considerably 

 extended. 



ICEBERGS. 



Icebergs are floating masses of ice which have been split off 

 from land glaciers. They are formed in both Arctic and Ant- 

 arctic regions, though under somewhat dissimilar conditions, 



