122 SCIENCE IN SHORT CHAPTERS. 



from the ridge separating the Handspikjen Fjelde from the 

 head of the Jostedal, where a view of the great neve or 

 sneefond is obtained. This side of the neve terminates in 

 precipitous rock- walls; at the foot of one of these is a dreary 

 lake, the Styggevand. The overflow of the neve here forms 

 great bending sheets that reach a short way down, and then 

 break off and drop as small icebergs into the lake.* 



The ordinary course of glaciers affords abundant illustra- 

 tions of the plasticity of such masses of ice. They spread 

 out where the valley widens, contract where the valley 

 narrows, and follow all the convexities or concavities of the 

 axial line of its bed. If the bending thus enforced exceeds 

 a certain degree of abruptness crevasses are formed, but a 

 considerable bending occurs before the rupture is effected, 

 and crevasses of considerable magnitude are commonly 

 formed without severing one part of a glacier from another. 

 They are usually V-shaped, in vertical section, and in many 

 the rupture does not reach the bottom of the glacier. Very 

 rarely indeed does a crevasse cross the whole breadth of a 

 glacier in such a manner as to completely separate, even 

 temporarily, the lower from the upper part of the glacier. 



If a glacier can thus bend downwards without "sunder- 

 ing its connection with the frozen mass behind," surely it 

 may bend upwards in a corresponding degree, either with 

 or without the f oraiation of crevasses, accoring to the thick- 

 ness of the ice and the degree of curvature. 



A glacier reaching the sea by a very steep incline would 

 probably break off, in accordance with Mr. Geikie's descrip- 

 tion, just as an Alpine glacier is ruptured fairly across when 

 it makes a cascade over a suddely precipitous bend of its 

 path. One entering the sea at an inclination somewhat 

 less precipitous than the minor limit of the effective rupture 

 gradient would be crevassed in a contrary manner to the 

 crevassing of Alpine glaciers. Its crevasses would gape 

 downwards instead of upwards have A-shaped instead of 

 a V-shaped section. 



With a still more moderate slope, the up-floating of the 



* See " Through Norway with a Knapsack," chapters xi. and xii., 

 for further descriptions of these. 



