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floebergs, and floating masses of old ice. Though then subjected to 

 repeated fracturing, with the fall in temperature of the air, it spreads 

 farther and farther into the sea, increasing in thickness and offering 

 more and more resistance to breaking up. Finally in the first months 

 of winter it reaches its maximum offshore extension, beyond which 

 the region of the pack is found. 



The development of the width of the fast ice belt depends upon the 

 configuration of the shore, since the more rugged the coast line and 

 the greater the number of islands in its vicinity, the greater is the 

 width of the fast ice ; it also depends upon the relief of the bottom, since 

 the shoaler the sea, the less prevalent are strong currents and wave 

 motion. Stranded hummocks in shoal water also assist fast ice 

 development. 



Assuming the height above water of floebergs to be 10 feet and their 

 draft to be 70 feet, the average depth for their free motion is about 

 12 fathoms. The floebergs ground in shoaler water, and thus the 

 whole area of fast ice is confined between the shore and the rampart of 

 ice heaps which lie approximately along the 12-f athom contour. 



The seats of fast ice are the broad continental shelves and their 

 spacious embay ments. The most striking example is the Siberian 

 Shelf, which has a mean width of -100 miles and a depth of 12 to 50 

 fathoms, its outer edge falling abruptly to the greater depths of the 

 Arctic Ocean. These regions produce a vast amount of fast ice, be- 

 cause the shallow depths favor early chilling, and the salinity of the 

 sea has been lessened by the discharge of numerous large rivers. The 

 Arctic coast of Eurasia, especially the shore of the East Siberian Sea, 

 has more extensive shallow water than is found elsewhere in the 

 Arctic Ocean. Here fast ice attains its greatest width, amounting 

 to 270 miles at its widest place off the mouth of the Yana. It has an 

 average thickness of 61^ feet and at times reaches a maximum thickness 

 of 9 feet. 



Another large area of fast ice, second only to that off Siberia, is 

 the sheet covering the labyrinth-like waterways of the Canadian 

 Arctic Achipelago. While small openings in some of the narrower 

 channels and straits may be kept unfrozen in winter by strong cur- 

 rents for long or short periods, the stabilizing effect of the large 

 number of islands promotes a maximum amount of stationary ice. 

 This is held fast in the archipelago region longer than in many other 

 localities because of the intricate channels and sounds. There are 

 other types of ice present as well, since the 12-f athom curve is generally 

 near shore. 



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