But to whatever combination of causes we attribute the great Alpine lakes one thing is clear, namely, that they are, geologically speaking, of modern origin. Every one must admit that the upper valley of the Rhone has been chiefly caused by fluviatile denudation, and it is obvious that the quantity of matter removed from that valley previous to the glacial period would have been amply sufficient to fill up with sediment the basin of the Lake of Geneva, supposing it to have been in existence, even if its capacity had been many times greater than it is now.[[8]]
On the whole, it appears to me, in accordance with the views of Professor Ramsay, M. Mortillet, Mr. Geikie, and others, that the abrading action of ice has formed some mountain tarns and many morainic lakes; but when it is a question of the origin of larger and deeper lakes, like those of Switzerland or the north of Italy, or inland fresh-water seas, like those of Canada, it will probably be found that ice has played a subordinate part in comparison with those movements by which changes of level in the earth’s crust are gradually brought about.
[1] Jamieson, Quart. Geol. Journ., 1860, vol. xvi, p. 370.
[2] Bryce, Quart. Geol. Journ., vol. xxi, p. 217, 1865.
[3] Geikie, Trans. Geol. Soc. Glasgow, vol. i, part ii, p. 68, 1863.
[4] Milne Home, Trans. Royal Soc. Edinburgh, vol. xxv, 1868-9.
[5] Quart. Geol. Journ., 1852, vol. viii, p. 372.
[6] Antiquity of Man, p. 313.
[7] Travels in Central Caucasus, 1869, p. 452.
[8] See Principles, vol. i, p. 420, 10th ed., 1867.