Vol. 54.] ON- THE GLACIAL GEOLOGY OE SPITSBEEGEN. 213 



lY. Maeine Ice and its Action. 



Spitsbergen offers exceptional opportunities for the study of the 

 geological action of marine ice, owing to its extensive shore-lines, 

 its deep fiords, its numerous exposed islets, the powerful currents 

 in the surrounding seas, and the rapid elevation which the land has 

 recently undergone. jS'evertheless, the results of tlie undoubted 

 agency of marine ice are not very conspicuous. 



The direct geological action of sea-ice is, so far as we could 

 learn, of four kinds : — 



(1) The transportation of material. 



(2) The contortion of shore-deposits. 



(3) The formation of small ridges and boulder-terraces above 



sea-level. 



(4) The striation, rounding, and furrowing of rocks. 



(1) The Transportation of Material. 



The three main types of sea-ice may all act as transporting 

 agents. Many of the blocks that floated down Ice Fiord were black 

 with moraine-matter, with which they had been charged when part 

 of a glacier. The ice-floes formed by the freezing of sea-water, 

 though at first quite pure, are driven ashore by wind or tide, and 

 there pick up a load of beach-material. In the case of the ice-foot 

 the base is charged with fragments of the beach, while its upper 

 surface is covered by the talus that falls upon it from the cliffs. 



Ice of all three kinds is sometimes stranded, and when it melts 

 away it deposits its load upon the shore. That this method of trans- 

 portation of material must take place is obvious, and it has been 

 repeatedly recorded. We need only remark that we saw many 

 patches of boulders and pebbles, which were far distant from their 

 place of origin. Along the shore of Ice Piord, between Advent Bay 

 and the head of Sassen Bay, there are boulders of gneiss from the 

 north-west of Spitsbergen, and heaps of Old Red Sandstone from 

 the head of North Piord and Klaas Billen Bay. 



(2) The Contortion of Shore-deposits. 



Ever since the boat-voyage of Dease & Simpson in 1837, along 

 the northern shores of British North America ^ it has been weE 

 known that the stranding of pack-ice has a very powerful action on 

 shore-deposits. 



The first result of this disturbance is the contortion of the layers 

 of beach-material, though this cannot be seen clearly until streams 

 have cut sections through the deposits. As one example, we may 

 cite a case observed at Pox Point on Cape Lyell, on the southern 

 shore of Bell Sound. 



The disturbances produced by stranding floes are not limited to 

 the spot actually struck by the ice, but frequently extend for some 



^ P. W. Dease & T. Simpson, ' An Account of [their] recent Arctic Dis- 

 coveries,' Journ. E. Geogr. Soc. vol. viii (1838) p. 221. 



Q. J. G. S. No. 214. Q 



