Some investigators have been inclined to explain the presence of boulders, moraines, drift, and the like phenomena, by the action of water. But even if we could believe that rivers had brought along with them such masses of rock, and deposited them where they are now found, the regularity in the distribution of the materials disproves any such theory. In the lateral moraines of the Lake of Geneva we have a striking illustration of this apparently systematic division of the loose materials; for the northeastern moraines of that glacial basin contain rocks belonging exclusively to the northern side of the 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.