ITHACA, October 26, 1868.
. . .I am passing some weeks here, and am studying the erratic phenomena, and especially the formation of the many small lakes which literally swarm in this region, and are connected in various ways with the glacial epoch. The journey which I have just completed has furnished me with a multitude of new facts concerning the glacial period, the long continuance of which, and its importance with reference to the physical history of the globe, become daily more clear to me. The origin and mode of formation of the vast system of our American rivers have especially occupied me, and I think I have found the solution of the problem which they present. This system reproduces the lines followed by the water over the surface of the ground moraines, which covered the whole continent, when the great sheet of ice which modeled the drift broke up and melted away. This conclusion will, no doubt, be as slow of acceptance as was the theory of the ancient extension of glaciers. But that does not trouble me. For my own part I am confident of its truth, and after having seen the idea of a glacial epoch finally adopted by all except those who are interested in opposing it on account of certain old and artificial theories, I can wait a little till the changes which succeeded that epoch are also understood. I have obtained direct proof that the prairies of the West rest upon polished rock. It has happened in the course of recent building on the prairie, that the native rock has been laid bare here and there, and this rock is as distinctly furrowed by the action of the glacier and by its engraving process, as the Handeck, or the slopes of the Jura. I have seen magnificent slabs in Nebraska in the basin of the river Platte. Do not the physicists begin to think of explaining to us the probable cause of changes so remarkable and so well established? We can no longer evade the question by supposing these phenomena to be due to the action of great currents. We have to do first with sheets of ice, five or six thousand feet in thickness (an estimate which can be tested by indirect measurements in the Northern States), covering the whole continent, and then with the great currents which ensued upon the breaking up of that mass of ice. He who does not distinguish between these two series of facts, and perceive their connection, does not understand the geology of the Quaternary epoch. . .
Of about this date is the following pleasant letter from Longfellow to Agassiz. Although it has no special bearing upon what precedes, it is inserted here, because their near neighborhood and constant personal intercourse, both at Cambridge and Nahant, made letters rare between them. Friends who see each other so often are infrequent correspondents.
ROME, December 31, 1868.
MY DEAR AGASSIZ,
I fully intended to write you from Switzerland, that my letter might come to you like a waft of cool air from a glacier in the heat of summer. But alas! I did not find cool air enough for myself, much less to send across the sea. Switzerland was as hot as Cambridge, and all life was taken out of me; and the letter remained in the inkstand. I draw it forth as follows.
One of the things I most wished to say, and which I say first, is the delight with which I found your memory so beloved in England. At Cambridge, Professor Sedgwick said, "Give my love to Agassiz. Give him the blessing of an old man." In London, Sir Roderick Murchison said, "I have known a great many men that I liked; but I LOVE Agassiz." In the Isle of Wight, Darwin said, "What a set of men you have in Cambridge! Both our universities put together cannot furnish the like. Why, there is Agassiz,—he counts for three."
One of my pleasantest days in Switzerland was that passed at Yverdon. In the morning I drove out to see the Gasparins. In their abundant hospitality they insisted upon my staying to dinner, and proposed a drive up the valley of the Orbe. I could not resist; so up the lovely valley we drove, and passed the old chateau of the Reine Berthe, one of my favorite heroines, but, what was far more to me, passed the little town of Orbe. There it stands, with its old church tower and the trees on the terrace, just as when you played under them as a boy. It was very, very pleasant to behold . . .Thanks for your letter from the far West. I see by the papers that you have been lecturing at the Cornell University.
With kindest greetings and remembrances, always affectionately yours,