he valley of the
Rhone, while the moraines on the southern shore of the lake consist of
rocks belonging to its southern side. Indeed, rivers, so far from
building up moraines, have often partially destroyed them. We find
various instances of moraines through which a river runs, having worn
for itself a passage, on either side of which the form of the moraine
remains unbroken. In the valley of the Rhone there are villages built on
such moraines, as, for instance, Viesch, with the river running through
their centre.

But if we need further confirmation of the fact that these accumulations
on either side of this and other Swiss lakes are ancient lateral
moraines, we have it in their connection with walls of a like nature at
their lower end, where we find again transverse moraines barring their
outlet, and also in the continuity of long trains of fragments of
similar rocks extending side by side across wide plains for great
distances without mixture. From the beginning of my investigations upon
the glaciers, I have urged these two points as most directly proving
their greater extension in former times, and more recent researches
constantly recur to this kind of evidence. All our lakes would be filled
with loose materials, had their basins not been sheltered by ice against
the encroachments of river-deposits during the transportation of the
erratic boulders to the farthest limits of their respective areas; and
all the continuous trails of rocks derived from the same locality would
have been scattered over wide areas, had they not been carried along, in
unyielding tracks, like moraines. On a small scale the waters of the
Rhone and of the Arve recall to this day such a picture. There are few
travellers in Switzerland who have not seen these two rivers, where they
flow side by side, meeting, but not mingling, at the southern extremity
of the lake, the different color of their water marking the two parallel
currents. In old times, when the glaciers filled all the valleys at the
base of Mont Blanc, and to the east of it, uniting in the valley through
which now runs the River Rhone, the glacier of the Arve came down to
meet the ice from the valley of the Rhone, in the same manner as the
River Arve now comes to meet the waters of the Rhone where they rush out
from the southern end of the lake.

This would be the proper place to consider the formation of the lakes of
Switzerland, as well as their preservation by the agency of glaci