GLACIAL EROSION AND TRANSPORTATION. 235 



weighed. In most of the text-books the formation of ice- 

 bergs is represented to be by the pushing out of the ice into 

 the water until the depth is such as to overcome its specific 

 gravity, and lift a mass of ice up bodily and float it away. 

 An inference from imperfect data by Dr. Kane has doubt- 

 less done much to foster this idea. 



Regarded upon a large scale, I am satisfied that the iceberg 

 is not disengaged by debacle, as I once supposed. So far from 

 falling into the sea, broken by its weight from the parent- 

 glacier, it rises from the sea. The process is at once gradual 

 and comparatively quiet. The idea of icebergs being dis- 

 charged, so universal among systematic writers and so recently 

 admitted by myself, seems to me now at variance with the 

 regulated and progressive action of Nature. Developed by 

 such a process, the thousands of bergs which throng these seas 

 should keep the air and w r ater in perpetual commotion, one 

 fearful succession of explosive detonations and propagated 

 waves. But it is only the lesser masses falling into deep 

 waters which could justify the popular opinion. The enor- 

 mous masses of the great glacier are propelled, step by step 

 and year by year, until, reaching water capable of supporting 

 them, they are floated off, to be lost in the temperature of 

 other regions.* 



Doubtless some icebergs are thus formed. But any tour- 

 ist to Alaska may now satisfy himself that the ordinary 

 method of the formation of an iceberg is by the breaking off 

 of masses from the top as that portion of the ice is pushed 

 on in advance of the lower strata. Still, as the fractures 

 vvould not always reach to the bottom of a deep inlet, masses 

 thus left below the water would eventually rise to the sur- 

 face in case the front of the ice were retreating, so as to 

 remove the superincumbent weight from them. 



Coming now to consider the direct action of glacial ice 

 in the transportation of solid material, we speak first of that 

 carried upon the surface. Apparently there is scarcely any 



* " Arctic Explorations," vol. ii, p. 148. 



