To Adolf von Morlot 28 November 
Down near Bromley | Kent
I received your letter of the 29th of October a week since. It would be presumptuous in me to give you credit for the spirit in which that letter is written; but I may say, that I think, that if you yourself were to see it in ten years hence, you would be pleased with it.— I am obliged for your German letter, which I must slowly spell out, for I am a miserable German scholar, & feel a difficulty in acquiring language, which I presume is unknown to yourself & many of your countrymen.—
Your news about the passage of trachyte is very interesting to me; & I shall be very curious to read, when published, Haidingers views on plutonic Geology:1 seeing that the earth gets hotter with an increasing depth & seeing from how many points, liquefied volcanic rocks have or do come to the surface, I cannot, (not knowing the full reasons) give up yet the old plutonic view.— With respect to the Löess, have you read what Lyell says in his later Editions of the Principles,2 & in his Paper in the Edin: New Phil: Journal, July 1834, & in the Proceedings of the Geolog: Soc: No. 36 & No 43.—3
With respect to the contemporaneousness of the now extinct great animals, with the ice Period, are you aware that in N. America, it can be clearly shown that they lived quite subsequently to the boulder-period. (V. Lyell in some late numbers of the Geolog. Proc:)4 & this is the case with one of the monsters of S. America.5 Dr Falconer is, also, sure, that when the great quadrupeds of India were alive, the country was much cooler.6
As you attend to volcanic rocks, let me call your attention to the probability of the zoned-glacier-structure of Forbes (to whom I have lately sent some specimens) throwing light on certain streams of lava of the obsidian & trachytic streams: I have given some facts in my small volume on Volcanic Islds on this subject.—7
Should you at any time come to England, I shall be happy to see you here, at my quiet country house; but if you expect any information from me, you will be disappointed, for I find myself falling far astern in the geological race of knowledge,—to an extent, which when I was strong, I had hoped, would not have happened for some years.—
With respect to passages in my letters, I feel almost certain that they contain nothing new or worth publishing; & they were written without care & with personal allusions to myself, which are not fit for any eye, but a correspondent’s: Pray, therefore, if you do publish any passage, be cautious, for I repeat, I am almost sure, there can be nothing worthy of anyone’s seeing.
Believe me | Yours very truly | C. Darwin
Mentions his Plutonic view of earth history.
Cites Lyell’s opinions on loess.
CD doubts contemporaneousness of extinct great animals with ice period.
Cites applicability of Forbes’s theory of glacier structure to structure of volcanic obsidian.
CD is falling astern in the geological race for knowledge.
Please cite as
Darwin Correspondence Project, “Letter no. 794,” accessed on 26 March 2017, http://www.darwinproject.ac.uk/DCP-LETT-794