112 POLAR PROBLEMS 



floating hummocks 



stranded hummocks (Russian, stamukhi), 

 d) State • j whose height is often 1 8 to 20 meters 



above sea level in the Siberian and 

 I Kara Seas (Figs. 14-15) 

 summer hummock 

 autumn hummock 

 winter hummock 

 spring hummock 

 pressure ridges 

 pressure areas 



e) Season 



f) Extent 



"The formation of the hummocks due to marginal crushing is a 

 primary process at which the hummocking can stop, after the kinetic 

 energy of the colliding ice masses has been spent, or the process may 

 pass into a further form of breaking up and piling up the broken 

 material" (Kolchak). 



"Winter and spring hummocks occur in those parts of the sea 

 where the ice is in motion during all the year, and they are not dis- 

 tinguished from the autumn forms except by their greater strength; 

 as for the summer hummock, which forms after the breaking up of 

 the immovable ice of winter, it is distinguished from the autumn 

 hummock not only by its greater strength but also by a difference in 

 its physical properties due to the influence of other temperature 

 conditions, other modes of melting, etc." (Kolchak). 



Stranded hummocks (stamukhi) are a very important type of 

 hummock, especially in the Russian sector of the Arctic, where the 

 width of the fast-ice depends, among other factors, mainly on the num- 

 ber of stamukhi present. In this respect as well as in the initial process 

 of ice formation they play the same role as grounded icebergs or 

 groups of small islands. 



When the process of hummocking takes place along the outskirts 

 of the pack ice (in the "frontier region of the Arctic Pack," to use 

 Kolchak's expression) the ice masses of the Arctic Pack participate 

 in the formation of pressure areas and pressure ridges. These massive, 

 compact ice masses, or hummocks of the pack ice and Arctic Pack 

 pressed and cemented together, are called floebergs. 



Small glagons of hummock origin are called growlers. 



Subdivisions of Derivatives of the Pack Ice 



As to fields, floes, and glagons, they may be divided as follows ac- 

 cording to: 



one year old 



Age^ 



many years old 



1° Strictly speaking, floes and glagons many years old occur mainly in the pack ice, while, on the 

 contrary, fields occur mainly in the Arctic Pack. 



