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Darwin Correspondence Project

To William Benjamin Carpenter   6 December [1844]

Down near Bromley Kent

Dec 6th.


I hope you will excuse the liberty I take in addressing you, but I trust that our several common acquaintances may be some excuse & Mr Lyell1 has been so good as to say that I might use his name as an introduction to you. My object in writing is to ask you to confer a favour on me by examining a specimen of calcareous rock. The great deposit of the Pampas, in which so many strange mammiferous remains are embedded, in its southern parts, passes into an indurated, calcareous, tuff-like stone. Comparing a specimen of this, with a specimen from a post-pleiocene calcareous bed from the coast of Chile, which has resulted from the attrition of recent shells, of which many are embedded in it, I was struck with the general resemblance between them, and especially in some minute, rounded, included fragments.—2

I am most anxious to know, whether these minute fragments, which are very indistinct, are really pieces of shells, like those in the Chilian stone, because the origin of the Pampæan formation has been lately disputed & attributed to a debacle, & is in many points of view of considerable interest.—3 Having seen some of your curious researches on the microscopical structure of shells,4 it has occurred to me, that perhaps you would be willing to confer this great favour on me;5 and would be so kind, if you think the little fragments in their matrix would stand cutting & polishing, to have it done at my expence.— Should you have time to spare to look at my specimen, I would send it (carriage free) either to anywhere in London, or perhaps better, direct to Ripley, if you would tell me by what conveyance is best—

Hoping that you will excuse the liberty which I am taking Pray | Believe me, dear Sir | Yours faithfully | Charles Darwin


Charles Lyell.
CD had been working on South America, the third part of the geology of the Beagle voyage, since 27 July 1844 (see Correspondence vol. 3, Appendix II). He described the Pampean formations in chapter 4, giving Carpenter’s conclusions on pp. 76–7. As a result of Carpenter’s examination of the specimens, CD concluded that it would be hazardous to conjecture that the Pampas rocks were, like those from Coquimbo, Chile, the result of attrition and decay of shell fragments. See also n. 5, below.
Alcide Charles Victor Dessalines d’Orbigny, in volume 3, part 3, of his Voyage dans l’Amérique Méridionale, had argued that the Pampas was formed as the result of the sudden deposition of a large quantity of mud (Orbigny 1835–47, 3 (pt 3): 82–4). Part 3 of volume 3 was published in 1842. CD, who followed Lyell’s uniformitarian theory of changes by ‘causes now in action’ (C. Lyell 1830–3, 1: 311), would have been interested in evidence of formations laid down by slow sedimentation, attested by the presence of sea-shells or their calcareous remains. See South America, p. 98.
Carpenter had read a paper ‘On the microscopic structure of shells’ at the York meeting of the British Association for the Advancement of Science, 26 September to 2 October 1844 (Report of the fourteenth meeting of the British Association for the Advancement of Science, held at York in September 1844, pp. 1–24).
See Correspondence vol. 3, letter to W. B. Carpenter, [11 or 18 December 1844], and letters from W. B. Carpenter, 21 December 1844, 2 January [1845], and 5 May 1845, and Correspondence vol. 7, Supplement, letter to W. B. Carpenter, 25 December [1844].


Asks WBC if he will examine a specimen of calcareous rock.

Letter details

Letter no.
Charles Robert Darwin
William Benjamin Carpenter
DE 7 1844
Source of text
DAR 185: 114

Please cite as

Darwin Correspondence Project, “Letter no. 797F,” accessed on 16 September 2021,

Also published in The Correspondence of Charles Darwin, vol. 13 (Supplement)