26 



IKIDTJOK NANSKN. 



M.-N. Kl. 







YWs. 9 & lo. The Buchanan and Murray Glaciers along tlic est 



Tilis may, to some great extent, be due to the alternating melting and 

 freezing of the ice and water, at the under side (^f the glaciers, caused by 

 sudden changes in pressure, as was mentioned on a preceding page. 

 It may also be caused by melting water coming from above in the summer, 

 and again freezing under the ice. As Werner Werenskiold has first 

 pointed out to me, the pressure under water filling holes in the ice, will b2 

 greater than under the ice at the same level, owing to the considerably 

 higher density of the liquid water. If the temperature is at melting point, 

 the ice may thus melt under the water, and this may continue down to the 

 bottom of the glacier, provided that the holes remain full of water. But 

 as soon as the pressure is reduced, the water will again freeze under the 

 glacier. Such holes, more or less filled with melting water, may often be 

 formed along the edges of the glaciers, between the ice and the rock, and 

 in this manner the disintegration of the rock may be increased. 



At the bottom of crevasses often formed near the inner edge of the 

 cirque-glaciers there may also be frequent changes of temperature above 

 and below freezing point, causing rapid disintegration of the rocks 

 [cf. W. D. Johnson, 1904]. 



It is, however, obvious that the cirque-glacxrs also erode the ground 

 by their movement. Although in most cases the movement of these small 

 glaciers mav not be considerable, we find that they have scoured and 

 polished the rocks on the floor of their cirques, they have smoothed the 

 edges and have plucked stones. Moreover their motion is of importance 

 by carrving away débris and detritus formed by the erosion. 



The whole process described above, may have a general denuding 

 effect upon the land surface where it works, which is considerably greater 

 than the average erosion of the inland ice. There is also this difference, 

 that it will be mainly limited to the land surface which is above the sea. 

 Given sufficient time, it might therefore be able to denude the coast land 

 towards sea-level and m'ght transform it into a fairly low, though uneven 

 plain, provided that the climatic conditions allow the cirque-glaciers to 

 descend to the sea. In Lofoten the cirques have actually been eroded to 

 some depth below present sea-level [cf. Heiland, Thorolf \'ogt, 1912. Ah!- 



