submerged part of the ice cannot exceed 0. 1. Consequently the value 



cannot be greater than 2 cm, and we have the right to disregard it for further references. 

 Therefore, from formula (15), we derive 



A/i = fc J^ . 



Sh (16) 



Substituting the values 6;^ = 1. 02, ^^ = . 80, and it = 36 cm (the rise of the hull 36 cm above 

 the ice sea level, as observed by the Sedov ) we get 



A ft = 46 cm. 



It is clear that a 46 cm thaw cannot refer to some individual point of the ice field, but it is 

 necessary to observe it as the average for the entire surface of the ice field. In even parts of the 

 ice field, the value of melting will be less; in the raised parts (hummocks and ropaki) it will be 

 more. It will be minimum under the snezhnitsa (snow puddles) where the water, being a foreign 

 absorber of the heat of solar radiation, will protect it from melting. 



That very same thing is related also to the change in the general thickness of ice. There, 

 where ropaki, hummocks and snow drifts are on the ice fields, the decrease in the thickness was 

 more significant. On the level places (on such where, for example, the measurements of thickness 

 of the ice cover were carried out at the time of the drift of the Sedov ) the changes of the ice thick- 

 ness was the smallest. 



The dimensions of the ice field in which the Sedov was frozen, are not known. If its area 

 was only about 1 square km in all, 46 cm of melted ice had to give about 400, 000 m of water, which 

 filled the snezhitsa (melt pools). While this water remained in the snezhitsa (melt pools), vertical 

 movements were caused only by a result of the summer freezing from below, due to the low temper- 

 atures of the ice itself, and this raising, as we have seen, would not exceed 2 cm (that is, it was 

 completely imperceptible). Moreover, such a rise could only be completed very slowly. 



From that moment, when large masses of water had begun quickly to leave the snezhitsa 

 (melt pools) and run under the ice, the ice began to rise above the level of the sea and together with 

 it the Sedov . 



It is possible that this circumstance contributed to this rise, in that ice was packed during the 

 winter under the Sedov with an overall thickness of 10 m, and "directly under" the Sedov , the 

 isostatic line was somewhat lower than the level of the sea, but the influence of the rise of the iso- 

 static surface cannot be determined in view of the lack of data. 



LITERATURE: 74, 77, 133. 



Section 104. Average Ice Thickness 



Ice fields, as we have seen, according to origin, may be accumulations of ice or cakes of ice. 

 The thickness of the first are more or less equal in their entire extent; the thickness of the second 

 changes from point to point within extremely wide limits. 



282 



