s of which are
dry for a large portion of the year. Right and left of the larger
gorges such secondary chasms are often found. The idea of time must,
I think, be more and more included in our reasonings on these
phenomena. Happily, the marks which the rivers have, in most cases,
left behind them, and which refer, geologically considered, to actions
of yesterday, give us ground and courage to conceive what may be
effected in geologic periods. Thus the modern portion of the Via Mala
throws light upon the whole. Near Berguen, in the valley of the
Albula, there is also a little Via Mala, which is not less significant
than the great one. The river flows here through a profound limestone
gorge, and to the very edges of the gorge we have the evidences of
erosion. But the most striking illustration of water-action upon
limestone rock that I have ever seen is the gorge at Pfaeffers. Here
the traveller passes along the side of the chasm midway between top
and bottom. Whichever way he looks, backwards or forwards, upwards or
downwards, towards the sky or towards the river, he meets everywhere
the irresistible and impressive evidence that this wonderful fissure
has been sawn through the mountain by the waters of the Tamina.

I have thus far confined myself to the consideration of the gorges
formed by the cutting through of the rock-barriers which frequently
cross the valleys of the Alps; as far as they have been examined by me
they are the work of erosion. But the larger question still remains,
To what action are we to ascribe the formation of the valleys
themselves? This question includes that of the formation of the
mountain-ridges, for were the valleys wholly filled, the ridges would
disappear. Possibly no answer can be given to this question which is
not beset with more or less of difficulty. Special localities might
be found which would seem to contradict every solution which, refers
the conformation of the Alps to the operation of a single cause.

Still the Alps present features of a character sufficiently definite
to bring the question of their origin within the sphere of close
reasoning. That they were in whole or in part once beneath the sea
will not be disputed; for they are in great part composed of
sedimentary rocks which required a sea to form them. Their present
elevation above the sea is due to one of those local changes in the
shape of the earth which have been of frequent occurrence throughout
geol