1921. No. 1 1. 



THE STRANDFLAT AND ISOSTASY. 



^D 



Fig. 8. Inner Nor\va\- Island, north coast ot" Spitsbergen [from Nansen, 1920]. 



Any profile of the Norwegian strandfiat gives the impression that the 

 land, rising between the sounds and submerged channels, has been truncated 

 and i)laned after the latter had been formed, and that there have been 

 relatively slight modifications of the relief after this happened. 



The Erosion of Local Glaciers. 



Another form of erosion is due to the activity of small "botten"- 

 glaciers or cirque-glaciers, and of snow and ice accumulated in depressions 

 and hollows of the rock surface, and remaining during the summer, or 

 at least a greater part of it. Along the edges of these glaciers and snow- 

 accumulations, the frost will have a strong disintegrating effect on the 

 rocks during the season when the snow is melting, and when there are 

 perpetual oscillations of temperature between frost and thaw. All joints 

 and fissures in the rocks are here kept full of melting wtaer, ready to burst 

 the rocks at each frost, that may even occur several times during the day 

 and night. The rocks are therefore rapidly eaten away and thumbling 

 flown on to the glaciers or snow-heaps w^hich carry them off. 



This erosion is thus a combination of glacial erosion and atmospheric 

 weathering (mainly by frost) which is especially powerful in glacial cli- 

 mates, and may be studied now at full work in Spitsbergen [cf. Nansen, 

 1920, 1921, Chap. VIII]. 



Fig. 6 represents cirque-glaciers now at work on the west coast of 

 Cross Bay, Spitsbergen. Fig. 7 illustrates the probable future effect of 

 this erosion when the cirque-glaciers have got time to cut through the 

 mountain walls beliind them. 



As was already pointed out by Amund Hellanrl and Lorange, there 

 must also be a very active vertical erosion under the cirque-glaciers 



