Glacial Erosion in Norway. 223 
soon as the resistance due to friction between the stones and the 
rock equals that due to viscosity, which, as observations show, is 
soon reached. Consequently, we should not expect to find great 
troughs or grooves scooped out of solid rock by the actual glacier. 
These I have not seen about the existing glaciers of Norway, which 
are not dependent upon atmospheric and aqueous erosion and the 
texture of the rock, although their surfaces may have been subse- 
quently polished. Generally speaking—as seen in the valley 
behind Fondalen Gaard, where the glacier is nearly free from sand, 
and contains comparatively few stones, as well as at many other 
places—the surfaces of the subjacent crystalline rocks, although of 
the form of roches moutonnées, with angles mostly removed, are not 
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l ower ey oction at Fondalsbreen, hh, zone along which ice (b) is flowing upon its 
, Smooth, but are as rough and as much weather-worn as similar 
rocks in warmer countries where no glaciers have been. U 
these surfaces, it is often difficult to discover scratches—even when 
Present—for they are often so faint as to be only rendered apparent 
by moistening the rock. Even the face of the hummocks are com- 
monly imperfectly polished. In other places, particularly at Tuns- 
bergdalbreen which contains much sand along the margin, the 
rocks are highly polished, and but little scratched. One is every- 
where surprised to find beneath the glaciers the great paucity of 
glaciated stones, and in many terminal moraines they are scarcely, 
if at all, to be found. * : 
The insufficiency of glaciers to act as great erosive agents is 
