THE ARCTIC PACK 137 



Up of large areas are frequent, whereas the forms due to crushing are 

 found relatively less often than in the Siberian Sea. The difference 

 in the character of ice between the Kara and Siberian Seas is very 

 noticeable near Cape Chelyuskin. Approaching this cape from the 

 west one can observe a sharp change in the floating ice: namely east 

 of the cape one meets more and more frequently thick many-years- 

 old masses of ice that indicate their northern origin and the greater 

 pressure to which they have been subjected. High grounded frag- 

 ments of various forms alternate with broken fields 18 to 20 feet 

 thick with a very irregular surface covered by hillocks and depressions 

 often filled with clear fresh water. As one approaches the edge of the 

 Arctic Pack, the ice becomes thicker and thicker, until finally one 

 sees extending beyond the horizon compact fields covered with ridges 

 and hills of hummocks and along their margins with piles of fresh 

 broken ice. 



The nearness of the edge of the Arctic Pack, which sometimes de- 

 scends to the northern coast of the New Siberian Islands and detaches 

 masses of its many-years-old heaped-up ice into more southern parts 

 of the Siberian Sea, gives to the ice of this sea an appearance sharply 

 distinct from the ice of the Kara Sea. Many-years-old ice of oceanic 

 origin, taking part in the motion of the ice of local formation, increases 

 its mass and produces greater effects of shock and pressure; this cir- 

 cumstance, in connection with the shallowness of the sea, is mainly 

 expressed in the form of grounded hummocks and prevents the develop- 

 ment of large areas of smooth ice, and this in turn produces heaped-up 

 formations that are readily changed into many -years-old forms. 



In general one may consider the mass of ice of the Kara Sea that 

 forms the pack of that sea as consisting of the fields of old ice of local 

 origin, whereas the pack of the Siberian Sea is of mixed formation, 

 namely local, almost exclusively heaped-up ice combined with ice 

 brought from the nearest region of the Arctic Pack. 



The Phenomenon of Polynya^^ 



Beyond the limits of the ice cover, immovable in winter, that 

 forms the fully developed coastal fast-ice, about which we spoke above 

 in Chapter 5^^, the ice is in motion during the whole year. This mo- 

 tion, depending as it does on winds and currents, may be directed 

 either towards the coastal fast-ice or away from it toward the sea. 

 According to which of these two takes place one will meet, at the 



IS Possibly the first presentation in a Western European language of the deductions outlined by 

 Kolchak in this section (without specifically ascribing them to him, however) will be found in J. Scho- 

 kalsky: La circulation dans les couches superficielles de la Mer Polaire du Nord, Ann. de Geogr., Vol. 

 33, 1924, pp. 96-104; reference on pp. 102-103 and map. — Transi.. Note. 



19 Chapter 5: The Coastal Fast-Ice and Its Development in Its Dependence on the Configuration 

 of the Coast, the Relief of the Bottom, and the Formation of Stranded Hummocks, or Stamukhi, 

 pp. 64-77. 



