In the same figure 97, it is shown, according to Makarov, the plan of a hummock which is 

 leveled from below. It is clear that this leveling increases by the fact that the low temperatures of 

 the blocks of ice which were packed under the ice at the time of the hummocking gradually increase 

 under the influence of the temperature of the adjacent layers of water and due to this, the under-ice 

 part of any ice hummock represents a uniform formation. 



Very few determinations of the internal structure of hummocks have been made. Conse- 

 quently, the observations which were carried out by Makarov at the time of the Ermak in 1899 in 

 the region to the north of Svalbard represent a great profit. 



The ice in this region was made up chiefly of ice blocks of two sizes, with regard to thick- 

 ness, 2 m and 1.4 m. The first occupies a water area of about 70 per cent; the second, about 25 

 per cent. The air holes and fissures were about 5 per cent. The ice heaps were made up of ice 

 blocks of the same dimensions. Thus, the largest of the hummocks was composed of 2 m ice 

 blocks, and its height over the ice surface was about 4-1/4 m. It was immutably shown in the 

 measuring of the thickness of the ice by boring with the help of a steam bore, that the ice consisted 

 of several layers which were separated from one another by layers of water. The results of one of 

 these measurings is cited below, which was made on 7 August 1899 at 80°44' north, 90°05' east. 



Makarov emphasizes that it is impossible to distinguish layer from layer when working with 

 the steam bore if they lie close, and therefore it is impossible that the upper layer of ice consisted 

 of two layers . The height of the above- water part of the measured himimock constituted 5 . 8 per 

 cent of the total thickness. 



When boring the ice in the gulf of Finland, which was carried out on 10 April 1899, Makarov 

 discovered that this hummock consisted of 7 layers, the most powerful of which was a little more 

 than a meter thick. 



Otto Sverdrup (the Captain of the From ) told Makarov that if one begins to make a hole in 

 polar ice, water would appear in the hole at the place of solder in two adjacent ice blocks. Sverdrup 

 cited as an example when even a 2 m thick ice block crept at the time of the hummocking on another 

 ice block of the same type for a distance of 200 m, but the ice blocks did not entirely freeze 

 together. 



Nordenskjold also told Makarov that the lumps which form a hummock are badly welded to- 

 gether and the underwater parts are almost completely unsoldered. 



*The spaces in the hummocks which were filled with water are called "water pockets. " Some- 

 times these pockets are completely isolated. 



272 



