From formula (2) it follows that the correlation between the above-ice and the under-ice parts 

 of the hummocks with one and the same angle of flow does not depend on the angle of slope. Putting 

 the proper meanings in formula (2) and namely, 



6 =1.02 and 6- = 0.90, we get 



W 1' 



s = 2.75 h. 



In figure 97 the scheme of the hummock was shown according to Makarov (reckoned for an 

 angle of slope of 45°, which it is necessary to regard as exaggerated). From the figure, as well as 

 from the form of formula (2), it is clear that in the case of an equal angle of slope, the basis of the 

 over- ice part and the under-ice part of the hummock are not equal. Consequently, the ice field, 

 especially the above-ice part of the ice hummock, will undergo a stress downward in the center of 

 the pileup and upward along the sides . 



"Therefore, " states Makarov, "the surface of the ice assumes a convex form, which Nansen 

 also observed. 



"When the thaw begins, water collects in the cavities of the hummock. The ice hummock 

 reaches, at the moment of its formation, its greatest depth, but then the ice begins to be leveled. 

 Weyprecht attests that sometimes shift at the bottom is audible, with the complete repose of the ice 

 at the top. This occurs probably as a result of the movement of water under the ice field. The 

 difference of the movements of the ice fields and of the water on which it lies, that is, the current 

 of the water, is that power which levels the lower depth of the ice. " 



/'' ? ? ■■-.. 



■••-, i 



i y 



\ t 



i / 



*-.. 



Figure 97. Scheme of a polar hummock according to Makarov. 



271 



