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 glaciers.  But this subject is so intricate, and has already given rise to so many controversies which could not be overlooked in this connection, that I prefer to pass it over altogether in silence.  Suffice it to say that not only are most of the lakes of Switzerland hemmed in by transverse moraines at their lower extremity, but the lakes of Upper Italy, at the foot of the Alps, are barred in the same way, as are also the lakes of Norway and Sweden, and some of our own ponds and lakes.  Strange as it may seem to the traveller who sails under an Italian sky over the lovely waters of Como, Maggiore, and Lugano, it is, nevertheless, true, that these depressions were once filled by solid masses of ice, and that the walls built by the old glaciers still block their southern outlets.  Indeed, were it not for these moraines, there would be comparatively few lakes either in Northern Italy or in Switzerland.  The greater part of them have such a wall built across one end; and but for this masonry of the glacier, there would have been nothing to prevent their waters from flowing out into the plain at the breaking up of the ice-period.  We should then have had open valleys in place of all these sheets of water which give such diversity and beauty to the scenery of Northern Italy and Switzerland, or, at least, the lakes would be much fewer and occupy only the deeper depressions in the hard rocks.