I had some talk with Murchison, who has been on a flying visit into Wales, and he can see no traces of glaciers, but only of the trickling of water and of the roots of the heath. It is enough to make an extraneous man think Geology from beginning to end a work of imagination, and not founded on observation. Lonsdale, I observe, pays Buckland and myself the compliment of thinking Murchison not seeing as worth nothing; but I confess I am astonished, so glaringly clear after two or three days did the evidence appear to me. Have you seen last "New Edin. Phil. Journ.", it is ice and glaciers almost from beginning to end. (500/1. "The Edinburgh New Philosophical Journal," Volume XXXIII. (April-October), 1842, contains papers by Sir G.S. Mackenzie, Prof. H.G. Brown, Jean de Charpentier, Roderick Murchison, Louis Agassiz, all dealing with glaciers or ice; also letters to the Editor relating to Prof. Forbes' account of his recent observations on Glaciers, and a paper by Charles Darwin entitled "Notes on the Effects produced by the Ancient Glaciers of Carnarvonshire, and on the Boulders transported by Floating Ice.") Agassiz says he saw (and has laid down) the two lowest terraces of Glen Roy in the valley of the Spean, opposite mouth of Glen Roy itself, where no one else has seen them. (500/2. "The Glacial Theory and its Recent Progress," by Louis Agassiz, loc. cit., page 216. Agassiz describes the parallel terraces on the flanks of Glen Roy and Glen Spean (page 236), and expresses himself convinced "that the Glacial theory alone satisfies all the exigencies of the phenomenon" of the parallel roads.) I carefully examined that spot, owing to the sheep tracks [being] nearly but not quite parallel to the terrace. So much, again, for difference of observation. I do not pretend to say who is right. LETTER 501. TO J.D. HOOKER. Down, October 12th, 1849.