AND CIRQUES IN NORWAY AND GREENLAND. 165 



bursting, not a scooping out, of the rocks has taken place. The high 

 mountains of Xorway often consist only of loose blocks and stones 

 split by the freezing water. There is some difference between the 

 exposed surface of the mountains and that beneath the glaciers ; for 

 on the latter water at 0° C. is constantly dropping down, easily frozen 

 by every draught of colder air under the glacier, and the glacier 

 itself is always present to remove the blocks. 



In the cirques, however, there are often little lakes, and it is more 

 difficult to account for the manner in which the glaciers have ex- 

 cavated these. They are not formed by moraines damming the 

 water, but are true rock-basins ; it does not seem likely that they 

 were mainly scooped out like the great lakes, along the sides of 

 which we see groovings and roches moutonnees one beside the other ; 

 for in the little lakes one often sees sharp-edged blocks covering the 

 bottom. "When the glaciers of the cirques filled these small lakes, so 

 as to leave but little water, it seems probable that the water thus left 

 would freeze in winter, so that the whole tarn would be frozen to 

 the bottom, and the rocks in that way be broken loose. Whatever 

 may be the manner in which these blocks are broken out, we see 

 from their situation and form that a bursting has taken place in 

 these tarns, which are the last works of the glaciers in the cirques. 



The cirques which occur isolated in the mountains are not essen- 

 tially different from the valleys which end in a cirque, as often they 

 differ only in size. Thus five valleys ending in cirques and three cirques 

 debouch into the main valley of Yeitestrand, in Sogn; all these are at 

 a much higher level than the main valley and along the same side 

 of it. They both occur in the same way, except that the valleys 

 are longer, their area being as much as twenty -five times as great 

 as that of the cirques. In many cirques at the heads of valleys, 

 both in Xorway and in Greenland, there are lakes with a moraine 

 in front, as in the mountain cirques. These moraines seem to indi- 

 cate that the glaciers remained longest here ; and the excavation of 

 a cirque with a lake in it at the head of the valley was perhaps ac- 

 complished at a later time by an isolated glacier, the upper end of 

 the valley being very well adapted for sheltering a glacier. 



Perhaps it may be said that the mountain cirques were most fre- 

 quently formed in the modern period, while the valleys terminated 

 by cirques are older, dating from the close of the Glacial epoch, 

 though some even of these are modern and still in process of forma- 

 tion. It is very difficult, if not impossible, to draw the line between 

 the work of rivers before and of glaciers during the Glacial epoch ; 

 but the valleys terminated by cirques show that the present form of 

 the valleys is due to glaciers. 



The relation between the occurrence of Lakes in Norway and the 

 different extents of Glaciers during the Glacial epoch. — In many fjord- 

 valleys of Western Xorway, and in still more flat valleys of Southern 

 Xorway, there is an intimate connexion between the extent of gla- 

 ciers and the occurrence of lakes. A traveller in the districts of 

 Hardanger, Sogn, and Xordfjord, in going from the heads of the 



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