ICE SCRATCHING AND ICE POLISHING 49 



rock is smoothed and polished, and the projecting harder 

 parts are not sharp and angular, but have the form of 

 rounded humps, compared to a sheep's back, and hence 

 called " roches vioutonneesr When we come within three 

 or four feet of such rocks we see that they are marked in a 

 peculiar way by straight scratches of all lengths from half 

 an inch upwards, and crossing one another at various angles, 

 though one direction that parallel to the valley predomi- 

 nates. These scratches are caused by bits of harder stone 

 which stick in the under surface' of the ice, like emery 

 powder on a lapidary's metal plate. They move slowly 

 along with the ice, and so scratch the rock. Separate 

 stones of hand-size may be picked up which have been 

 scratched in this way, and their appearance is very dis- 

 tinctive. We know of no agency except that of moving 

 ice by which loose stones and rocks can be made to scratch 

 one another so as to give this special appearance. And 

 accordingly, when we find such rocks in Wales and Scotland, 

 and such stones in the " drift " and even below the Red 

 Crag of Suffolk, we are led to the guess, which is con- 

 firmed by a great mass of additional evidence, that glaciers 

 or great masses of moving ice existed formerly on the 

 mountains of Wales and the plains of East Anglia. 



Whilst the rocks which are covered, or were at one 

 time covered, by the ice of a glacier are rounded, smoothed 

 and scratched, the higher rocks which have never been 

 submerged by the moving ice-mass stand out sharp and 

 angular. They are continually broken and shattered by 

 the action of frost, and shower down on to the glaciers 

 their fragments, and sometimes immense masses of rock, 

 which accumulate like a huge railway embankment at the 

 sides of the glacier, or are slowly carried along by it as 

 they rest on its surface (like a passenger on one of the 

 new moving platforms or inclines), and so are deposited 

 at the end when the glacier melts away. These heaps of 



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