John Tyndall to Faraday   25 July 1864

Pontresina. | 25th, July, 1864.

My dear Mr Faraday

Thus far this year has been a bad year for Switzerland; the weather has been so capricious that even the few clear days which have been interspersed among the shaded and rainy ones could not, for want of faith in their continuance, be turned to proper account. I came here more than a fortnight ago. Immediately after my arrival I began a series of measurements on the two accessible glaciers -- the Morteratsch and the Rosegg glaciers -- which have yielded instructive results. I quitted London much worn down; I am now strong, -- but in passing from weakness to strength I had to go through an illness of four days, which seemed to produce a revolution in my system. In fact, I got wet upon the glacier before I was able to bear a wetting, and suffered in consequence. This is a very beautiful portion of Switzerland, and were the weather favourable this village would be a capital headquarters for a month. There are many delightful excursions in the neighbourhood; the mountains are noble and finely formed; the distant snow fields beautiful, and the valleys, clothed with pines and enlivened by musical rivers, have an air of comfort about them which I have not seen elsewhere in Switzerland. The people also are frank and civil. This year I have been interested to a greater extent than ever in the question as to how the Alps have assumed their present forms. Two rival opinions now divide geologists:- one is that the valleys of the Alps and the lakes of Switzerland and Italy are open fissions, produced by the cracking of the earth’s crust; the other is that the valleys have been produced in the main by erosion, and that even the lakes themselves have been scooped out by the long continued action of the ancient glaciers. There are difficulties in the way of each of these hypotheses; but I cannot help thinking that the theory of erosion stands upon the most solid basis. It appeals to agencies which are known to exist or to have existed, and which, if granted sufficient time, are certainly competent to produce the effect ascribed to them. Whereas the crack and fissure hypothesis labours under the disadvantage of being a creature of the imagination; it invokes agencies which we have never seen in action, and, even granting the hypothesis, there are various phenomena in the Alps which cannot without the most artificial assumptions be reconciled with it. My own notion is that the swelling from which the Alps have been sculptured has been produced during those slow changes of form which a mass like the earth may be expected to undergo. That from the moment the first portion of this protuberance emerged from the sea, erosion agents have been acting upon it. Water courses cut their way into the mass, and formed the first ravines; then in process of time came the stupendous glaciers of the so called glacial epoch, ploughing out the valleys with irresistable [sic] might. The shapes of the mountains, and the forms of the valleys suggest immediately, in nine cases out of ten, an origin of this kind. You may take your stand upon a commanding peak and see before you valleys which the most thorough going plutonist must ascribe to erosion. You may pass from these smaller valleys by insensible gradations to the largest valleys of the Alps, and the plutonist shall not be able to point out the place where erosion ceases to be the principal agent and where cracks and fissions begin. It is by thus acquiring the key among the smaller phenomena that we proceed with from [sic] steps to the larger ones. And what a hoary antiquity does this process of erosion indicate! This antiquity may appear trivial in comparison with the other epochs conceived in the consolidation of our planet; those other epochs, however, cease to impress us because they so much surpass the range of our conceptions. But the sculpturing of the Alps by ice and water comes in some measure within this range; the mind can rise to the level of the problem, and realize the might of Time without being crushed by the sense of its incompetence to seize upon the Infinite to which all those changes must ultimately be referred. Kindest regards to Mrs Faraday and Miss Barnard.

Yours ever sincerely | John Tyndall

I leave this place the day after tomorrow but hope to return to it in about 10 days. Would you kindly ask Smith to direct my letters here as before?