126 
SCENERY OF SWITZERLAND. 
the melting. That on the Aar glacier rises 20, 40, 
and even 60 metres above the general surface, and 
from the summit of the Sidelhorn it gives the im- 
pression of a wide black wall separating two white 
rivers. In Greenland such ice-walls have been known 
to attain a height of 125 metres. 
We can hardly have a better introduction to 
the study of glaciers than a visit to the Rhone 
glacier. The upper part, which is not shown 
in the figure, is a magnificent and comparatively 
smooth ice-field. Then comes a sharp descent, where 
in a river we should have a cascade or series of 
cascades, and where the ice breaks into a series of 
solid waves. The crests gradually melt, and as dust 
and stones collect in the hollows, and the centre of 
the glacier moves more rapidly than the sides, we 
have a succession of dirt bands which curve across 
the glacier. 
Below the fall, the bed of the glacier becomes 
again comparatively flat; the glacier is squeezed out 
so as to become considerably wider, and as the ice 
cannot expand it splits into a number of diverging 
crevasses. This was much more marked when I 
first visited the glacier in 1861, and when it was 
much larger than at present. 
If we start from the hotel, after crossing the river, 
