ICE AND GLACIEKS. 121 



Fig. 17 represents one of the more level parts of the 

 Mer de Glace at the Montanvert, the little house of 

 which is seen in the background. The Gries Glacier, 

 where it forms the height of the pass from the Upper 

 Ehone valley to the Tosa valley, may even be crossed on 



FIG. 17. 



horseback. We find the greatest disturbance of the 

 surface of the glacier in those places where it passes 

 from a slightly inclined part of its bed to one where the 

 slope is steeper. The ice is there torn in all directions 

 into a quantity of detached blocks, which by melting 



