Prof. Tyndall on the Conformation of the Alps. 269 



Comparing the three lines together, it will be observed that 

 the velocity diminishes as we descend the glacier. In 100 hours 

 the maximum motion of the three lines respectively is as follows: — 



Maximum Motion in 100 hours. 



Line A 56 inches. 



» B 45 „ 



„ C 30 „ 



This deportment explains an appearance which must strike 

 every observer who looks upon this glacier from the Pitz Lan- 

 guard, or from the new Bernina Road. A medial moraine runs 

 along the glacier, commencing as a narrow streak high up ; but 

 towards the end the moraine extends in width, and finally 

 quite covers the terminal portion of the glacier. The cause of 

 this is revealed by the foregoing measurements, which prove that 

 a stone on the moraine where it is crossed by the line A, ap- 

 proaches a second stone on the moraine where it is crossed by 

 the line C with a velocity of 26 inches in 100 hours. The 

 moraine is in a state of longitudinal compression. Its materials 

 are more and more crowded together, and must consequently 

 move laterally and render the moraine at the terminal portion 

 of the glacier wider than above. 



The motion of the Morteratsch glacier, then, diminishes as we 

 descend. The maximum motion of the third line is 30 inches 

 in 100 hours, or 7 inches a day — a very slow motion ; and had 

 we run our lines nearer to the end of the glacier, the motion 

 would have been slower still. At the end itself it is nearly 

 insensible. Now I submit that this is not the place to seek for 

 the scooping power of a glacier. The opinion appears to be pre- 

 valent that it is the snout of a glacier that must act the part 

 of ploughshare ; and it is certainly an erroneous opinion. The 

 scooping power will exert itself most where the weight, and con- 

 sequently, other things being equal, the motion is greatest. A 

 glacier's snout often rests upon matter which has been scooped 

 from the glacier's bed higher up. I therefore do not think that 

 the inspection of what the end of a glacier does or does not 

 accomplish can decide this question. 



The snout of a glacier is potent to remove anything against 

 which it can fairly abut ; and this power, notwithstanding the 

 slowness of the motion, manifests itself at the end of the Mor- 

 teratsch glacier. A hillock, bearing pine trees, was in front of 

 the glacier when Mr. Hirst and myself inspected its end ; and this 

 hillock is being bodily removed by the thrust of the ice. Several 

 of the trees are overturned ; and in a few years, if the glacier 

 continues its reputed advance, the mound will certainly be 

 ploughed away. 



