ORIGIN OF ICEBERGS 123 



no such strong currents as those which sweep down the shores 

 of Labrador to convey these packs of ice to the parts of the 

 sea which are most traversed by shipping ; they are rarely 

 encountered except by the whalers or the rare explorers who 

 have attained to these lonely waters of the far southern seas. 

 We have now completed our general account of the simpler 

 and least important of the groups of floating ice-fields. We 

 have next to examine into the processes which lead to the 

 formation of the far grander masses, the true icebergs. 



We have already noted the fact that icebergs differ from 

 floes in that they are far greater in depth ; it is also character- 

 istic of them that they are composed of a dark blue variety of 

 ice, which is generally much more solid than that of the floes. 

 The berg-ice has also the peculiar feature that it tends to rift 

 in a vertical direction, which gives their crests the striking and 

 beautiful outlines so characteristic of them where they have 

 been much decayed by long exposure to the warm air of the 

 region of the sea to which they attain near the end of their 

 journeys. To understand these peculiar features it is again 

 necessary for us to consider the regions where these ice- 

 masses are formed. It is now well known that all true bergs 

 — and in this class are included all the floating masses which 

 find their way down to the line now followed by the trans- 

 atlantic steamers— have their origin in the glaciers of high 

 latitudes. Those which beset the pathway of ships moving 

 from Europe to America are all cradled in Greenland. All 

 the lands north and west of Spitzbergen are more or less 

 occupied by fields of perpetual snow, which, slowh' descend- 

 ing tlie valleys, is by pressure and by its forward movement 

 converted into pure translucent ice; all the little cavities con- 

 taining vesicles of air, which gives to snow or powdered ice 



