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Darwin Correspondence Project

To Charles Lyell   [18 November 1849]

Down

Sunday

My dear Lyell

I remembered the passage in E. de B.1 & have now reread it— I have always & do still entirely disbelieve it: in such a wonderful case he ought to have hammered every inch of rock up to actual junction; he describes no details of of junction & if I were in your place I would absolutely dispute the fact of junction (or articulation as he oddly calls it) on such evidence. I go further than you; I do not believe in the world there is or has been a junction between a dike & stream of lava of exact shape of either (1) or (2)—2 [DIAGRAMS HERE] stream (1) dike (2)

If dikes gave immediate origin to volcanic vents, we shd have craters of this elliptic shape.— [DIAGRAM HERE]

I believe that when the molten rock in a dike comes near to the surface, some one two or three points will always certainly chance to afford an easier passage upwards to the actual surface, than along the whole line, & therefore that the dike will be connected, (if the whole were to be bared & dissected) with the vent by a column or cone (see my elegant drawing) of lava. I do not doubt that dikes are thus indirectly connected with eruptive vents.— E. de B. seems to have observed many of his [DIAG HERE]; now without he supposes the whole line of fissure or dike to have poured out lava (which implies as above remarked craters of an elliptic or almost linear shape) on both sides, how extraordinary improbable it is, that there should have been in a single line of section so many intersections of points of eruption; he must, I think, make his orifice of eruption almost linear or if not so, astonishingly numerous.—

One must refer to what one has seen oneself; do pray, when you go home, look at the section of a minute cone of eruption at the Galapagos p. 1093 —which is the most perfect natural dissection of a crater which I have ever heard of, & of the drawing of which you may, I assure you, trust;—here the arching over of the streams as they were poured out over the lip of the crater was evident & are now thus seen united to the central irregular column .— Again at St. Jago, I saw some horizontal sections of the bases of small craters, & the sources or feeder were circular.

I really cannot entertain a doubt that E. de B is grossly wrong, & that you are right in your view.— but without most distinct evidence I will never admit that a dike joins on rectangularly to a stream of lava.— Your argument about the perpendicularity of the dikes strikes me as good.—

The map of Etna, which I have been just looking at, looks like a sudden falling in, does it not?— I am not much surprised at the linear vent in Santorin. (this linear tendency ought to be difficult to a circular=crater=of=elevation believer); I think Abich describes having seen same actual thing forming within crater of Vesuvius.—4 In such cases, what outline do you give to upper surface of the lava in the dike connecting them; surely it wd. be very irregular & would send up irregular cones or columns, as in my above splendid drawing.—

At the Royal on Friday, after more doubt & misgiving, than I almost ever felt, I voted to recommend Forbes for Royal Medal,5 & that view was carried, Sedgwick taking the lead.—

I am glad to hear that all your party are pretty well— I know from experience what you must have gone through— From old age with suffering, death must be to all a happy release.6 I hope Mrs. H. Lyell is pretty well—7

With our kind remembrances. | Ever yours | C. Darwin

I saw Dan. Sharpe the other day & he told me he had been working at the Mica schist (ie not gneiss) in Scotland & that he was quite convinced that my view was right—8 you are wrong & a heretic on this point I know well.— [DIAGRAM HERE] small orifice of eruption volcanic strata volcanic strata strata Dike Dike Dyke supposed to be seen laterally ie not in section X upper surface of dike.—

Footnotes

Jean Baptiste Armand Louis Léonce élie de Beaumont’s researches on Mount Etna (1838). The particular passage referred to is élie de Beaumont 1838, pp. 148–50. CD’s copy of this volume, with notes on this and other passages, is in the Darwin Library–CUL. CD evidently had discussed élie de Beaumont’s views with Lyell in the interval between this letter and letter to Charles Lyell, [1 November 1849].
Lyell did dispute the nature of the junction as described by élie de Beaumont, taking up CD’s point about the need to have hammered the rock, in C. Lyell 1850a, pp. 230–1. CD retreated from this position in his next letter to Charles Lyell, 4 December [1849].
The award created difficulties between the council and the sectional committee for geology, since the latter voted to recommend James David Forbes in the face of opposition from the council. The council ignored the recommendation and directed the committee to reconsider their nominations on 26 November. On that day the committee decided to nominate Gideon Algernon Mantell, a recommendation which the council accepted (M. B. Hall 1984, p. 88, in which J. D. Forbes is mistakenly identified as Edward Forbes). Mantell described part of the debate in his journal (Curwen ed. 1940, pp. 245–7).
Lyell’s father had died on 8 November 1849.
Katharine Murray Lyell, Mrs Henry Lyell.
CD’s view was that foliation and cleavage were consequences of the same process and entirely different from stratification. Daniel Sharpe’s paper was read at the Royal Society, 1 November 1851.

Bibliography

Abich, Otto Hermann Wilhelm. 1841. Geologische Betrachtungen über die vulkanischen Erscheinungen und Bildungen in Unter- und Mittel-Italien. Braunschweig.

Hall, Marie Boas. 1984. All scientists now: the Royal Society in the nineteenth century. Cambridge: Cambridge University Press.

Volcanic islands: Geological observations on the volcanic islands, visited during the voyage of HMS Beagle, together with some brief notices on the geology of Australia and the Cape of Good Hope. Being the second part of the geology of the voyage of the Beagle, under the command of Capt. FitzRoy RN, during the years 1832 to 1836. By Charles Darwin. London: Smith, Elder & Co. 1844.

Summary

Criticises Élie de Beaumont’s view of a right angle junction of a stream of lava and a dike.

Mentions his misgivings in voting to recommend J. D. Forbes for Royal Medal.

Notes Daniel Sharpe’s work on mica schist.

Letter details

Letter no.
DCP-LETT-1271
From
Charles Robert Darwin
To
Charles Lyell, 1st baronet
Sent from
Down
Source of text
American Philosophical Society (Mss.B.D25.84)
Physical description
6pp sketch

Please cite as

Darwin Correspondence Project, “Letter no. 1271,” accessed on 21 January 2020, https://www.darwinproject.ac.uk/letter/DCP-LETT-1271.xml

Also published in The Correspondence of Charles Darwin, vol. 4

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