ARCTIC SEA ICE 



119 



Arctic Pack under the influence of wind, decreasing when it blows 

 toward and increasing when it blows away from the fast-ice. 



Further details about this polynya may here be waived as its ex- 

 istence and the causes therefore are well known; also, it is dealt with 

 by Kolchak in the chapter from his report that constitutes the next 



Fig. 17 — The Arctic Pack north of Cape Hecla, Grant Land, in April, 1902, showing the effect 

 of the shock and pressure characteristic of this region. (Photograph by R. E. Peary.) 



article. With regard to the other polynya it may not be amiss to 

 present a more detailed analysis, as the reasons for its existence have 

 so far been less fully discussed. 



Peary's Big Lead 



The polynya off Grant Land and northern Greenland might, to 

 employ the two words used to describe it by him to whom we owe 

 our sole knowledge of it, be termed Peary's Big Lead. Based on 

 Peary's repeated observations the following data about this lead are 

 available: (i) Most of it seems to be situated out beyond the conti- 

 nental shelf where the depth of the sea exceeds looo meters; (2) its 

 location is between latitudes 84° and 84>^° N., and it has been met 

 with on the meridians of 40° and 69° W. ; (3) its maximum observed 

 width is about 2 miles, i. e. much less than that of the Great Siberian 

 Polynya. 



Besides that there are the following known physico-geographical 

 factors which are inherent in this locality: (i) the great shock and 

 pressure of ice masses upon the northern shores of Greenland and 

 Grant Land; (2) the eastward direction of the drift of the Arctic Pack 



