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Darwin Correspondence Project

To Andrew Crombie Ramsay   9 April [1853]

Down Farnborough Kent

Ap. 9th.

Dear Ramsay

I feel so much interest on the subject of foliation & cleavage, & I was so much interested & pleased at your few remarks on the Duke of Argyle’s paper,1 that you must let me send you a few lines. As I was compelled to leave, I do not know whether you read your own paper;2 but before you do so or publish, will you oblige me by running your eye again (if ever read) over my remarks p. 162–168 in my Geological volume on S. America & especially p. 167, in which I say that as in some case the foliation supervenes on cleavage “so, perhaps, in some instances, the foliation of a rock may have been determined by the original planes of deposition or of oblique current laminæ”. It now seems you have found such instances:3 indeed I once saw one but so wretched & doubtful an example that I did not think it worth notice.

Please observe that I have shown some (probably not enough) caution in other places in speaking of foliation (as not resulting from the planes of deposition) as confined to the cases of the large areas examined by me. That foliation can supervene without preexisting cleavage or stratification, I must still think (p. 167 of my volume) from the “grain” of some certainly plutonic rocks, which are passing into gneiss.— I remember being on the point of coming to your conclusion as far as I heard it, (always perhaps giving too much importance to cleavage over stratification), when I thought of the facts of the “grain” &c in plutonic rocks.

I have fought so many battles vivâ voce, with Sir C. Lyell,4 that I have my pluck up on the subject, so do read over the above passages in my volume, & forgive me for troubling you.

Very sincerely your’s | Charles Darwin

Footnotes

Ramsay’s remarks were made at the Geological Society meeting of 6 April 1853, at which George Douglas Campbell, Duke of Argyll, had read a paper on ‘The granite district of Inverary, Argyllshire’ (Campbell 1853).
Ramsay’s paper on the lower Palaeozoic rocks of North Wales and Shropshire was not read until the meeting of 20 April. A footnote, probably added because of this letter, reads as follows: ‘In 1846 Mr. Darwin, in his “Geology of South America,” takes notice of the probability of foliation being found in the general direction of the planes of bedding and oblique lamination, and minutely and ably describes the passage of cleavage into foliation. His remarks on this subject form a perfect model of the true mode of investigating the subject.’ (Ramsay 1853, p. 172 n.).
Ramsay 1853, pp. 171–2. Ramsay concluded (p. 172) that: It is not intended to be implied … that foliation in all cases generally follows the planes of bedding, but only that, if the rocks be uncleaved when metamorphism takes place, the foliation planes will be apt to coincide with those of bedding; but, if intense cleavage has occurred, then it may be expected that the planes of foliation will lie in the planes of cleavage.
Charles Lyell was not convinced by CD’s views on foliation. See Correspondence vol. 4, letter to Charles Lyell, [on or before 20 January 1847], n. 2, and, in this volume, letters to Charles Lyell, [November–December 1851], and to Daniel Sharpe, 16 October [1851], n. 5.

Summary

Discusses geological foliation and cleavage. Urges ACR to read CD’s remarks on subject in his South America before ACR publishes his paper ["On the lower Palaeozoic rocks", Q. J. Geol. Soc. Lond. 9 (1853): 161–79].

Letter details

Letter no.
DCP-LETT-1512
From
Charles Robert Darwin
To
Andrew Crombie Ramsay
Sent from
Down
Source of text
American Philosophical Society (106)
Physical description
5pp

Please cite as

Darwin Correspondence Project, “Letter no. 1512,” accessed on 17 January 2019, http://www.darwinproject.ac.uk/DCP-LETT-1512

Also published in The Correspondence of Charles Darwin, vol. 5

letter