THE CONTINENTAL GLACIERS OF POLAR REGIONS 291 



which its coast is so deeply indented. Into the heads of these fjords 

 the tongues from the inland ice descend generally to the sea level 

 and below. The glacier ice is thus directly attacked by the waves 

 as well as melted in the water, so that it terminates in the fjords 

 in great cliffs of ice (Fig. 317). It is also believed to extend 

 beneath the water surface as 

 a long toe resting upon the 

 bottom (Fig. 319). 



The exposed cliff is notched 

 and undercut by the waves in 

 the same manner as a rock cliff, 

 and the upper portions override 

 the lower so that at frequent in- 

 tervals small masses of ice from 



this front separate on crevasses, and toppling over, fall into the 

 water with picturesque splashes. Such small bergs, whose birth 

 may be often seen at the cliff front of both the Greenland and 

 Alaskan glaciers, have little in common with those great floating 

 islands of ice that are drifted by the winds until, wasted to a frac- 

 tion only of their former proportions, they reach the lanes of trans- 

 atlantic travel and become a serious menace to navigation (Fig. 318). 



Northern icebergs of large dimensions are born either by the lifting 

 of a separated portion of the extended glacier toe lying upon the 

 bottom of the fjord, or else they separate bodily from the cliff 



FIG. 318. A Greenlandic iceberg after a 

 long journey in warm latitudes. 



FIG. 319. Diagram showing one way in which northern icebergs may be born 

 from the glacier tongue (after Russell). 



itself, apparently where it reaches water sufficiently deep to float it. 

 In either case the buoyancy of the sea water plays a large role in its 

 separation. 



If derived from the submerged glacier toe (Fig. 319), a loud noise 

 is heard before any change is visible, and an instant later the great 



