252 
TRANSPORTING POWER OF RIVERS. 
I do not mean to assert tliat all the rocky valleys of the 
Alps have been produced by the action of torrents resulting 
from the destruction of the forests. All the greater, and many 
of the smaller channels, by which that chain is drained, owe 
their origin to higher causes. They are primitive fissures, 
ascribable to disruption in upheaval or other geological con¬ 
vulsion, widened and scarped, and often even polished, so to 
speak, by the action of glaciers during the ice period, and but 
little changed in form by running water in later eras.* 
In these valleys of ancient formation, which extend into 
the very heart of the mountains, the streams, though rapid, 
have lost the true torrential character, if, indeed, they ever 
possessed it. Their beds have become approximately constant, 
and their walls no longer crumble and fall into the waters that 
wash their bases. The torrent-worn ravines, of which I have 
spoken, are of later date, and belong more properly to what 
may be called the crust of the Alps, consisting of loose rocks, 
of gravel, and of earth, strewed along the surface of the great de¬ 
clivities of the central ridge, and accumulated thickly between 
their solid buttresses. But it is on this crust that the moun¬ 
taineer dwells. Here are his forests, here his pastures, and the 
ravages of the torrent both destroy his world, and convert it 
into a source of overwhelming desolation to the plains below. 
Transporting Power of Rivers. 
An instance that fell under my own observation in 1857, 
will serve to show something of the eroding and transporting 
* The precipitous walls of the Yal de Lys, and more especially of the 
Val Doveria, though here and there shattered, show in many places a 
smoothness of face over a large vertical plane, at the height of hundreds 
of feet above the bottom of the valley, which no known agency but glacier 
ice is capable of producing, and of course they can have undergone no sen¬ 
sible change at those points for a vast length of time. The beds of the 
rivers which flow through those valleys suffer lateral displacement occa¬ 
sionally, where there is room for the shifting of the channel; but if any ele¬ 
vation or depression takes place in them, it is too slow to be perceptible 
except in case of some merely temporary obstruction. 
