Yol. 54.] ON THE GLACIAL GEOLOGY OF SPITSBEKGBN. 219 



(2) The UpMU Flow of Glaciers. 



With regard to the cause of glacier-movements we have no fresh 

 information. We found nothing inconsistent with the view that 

 the flow is due to the action of gravity alone. The one apparent 

 case of uphill advance with which we met may be as easily explained 

 by local subsidence of the upper part of the glacier, owing to 

 diminished snowfall, as by assigning climbing powers to the ice. 



We do not deny that ice may sometimes surge upward when meet- 

 ing obstacles in its path, a fact which probably explains such local 

 variations in the level of a glacier as those described by Bonney ^ 

 and Kendall^ on the Gorner Glacier, by Chamberlin ^ and Wright* 

 in Greenland, or the slight upbending of a thin glacier-snout over 

 a moraine as recorded in the case of the Glacier de Zigiore Nuove 

 by Sherwood.^ 



In the case of Greenland a great upward movement of ice is 

 often assumed, on the ground that ice formed in the interior has to 

 climb over a marginal mountain-chain. Thus Prof. Crosby ^ tells 

 us that ' it is the general belief of geologists that if Greenland were 

 divested of its ice -cap it would exhibit continental relief — elevated 

 margins and a depressed interior.' This view of the geographical 

 structure of Greenland appears improbable. Geologically Greenland 

 is very similar to Spitsbergen. It very likely consists of a high 

 plateau of sedimentary deposits supported on a great block of 

 Archaean rocks, which are exposed round the margins. The hypo- 

 thesis that there is a great depression in Central Greenland is not 

 one upon which it is safe to base an argument. 



(4) The Uplift of Material and. Land-ice. 



Nevertheless we found evidence, which we regard as conclusive, 

 of the upraising of materials in glaciers. We can see no other 

 satisfactory explanation of the occurrence of shells, whalebone- 

 fragments, and driftwood in the Ivory Glacier moraines at an 

 elevation greater than that of any raised beach known in the 

 district. The bearing of this fact on the origin of the British high- 

 level, shell-bearing drifts is obvious ; but that question is also 

 affected by the character of the earth-movements now taking place 

 in Spitsbergen. The archipelago is now undergoing elevation, part 

 of which at least must be positive, since the rate of movement 

 varies horizontally. Thus the highest terraces we saw were those 

 at Cape Starashchin, which slope downward towards the east. The 



1 T. G. Bonney, ' Ice-blocks on a Moraine,' Nature, vol. xl (1889) p. 391. 



^ P. F, Kendall, ' Geological Observations upon some Alpine Glaciers,' Glac. 

 Mag. vol. ii (1894) p. 121. 



3 T. 0. Chamberlin, ' Glac. Stud. Greenland,' Jom-n. Geol. vol. v (1897) 

 p. 231. 



* G. F. Wright & W. Upham, ' Greenland Icefields,' 1896, p. 95. 



5 W. Sherwood, ' Glaciers of Val d'Herens,' Nature, vol. xlvii (1892) p. 174. 



6 W. O. Crosby, ' Englacial Drift,' Amer. Geol. vol. xvii (1896) p. 225. 



