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Letter 1008

Darwin, C. R. to Ramsay, A. C.

10 Oct [1846]

    Summary Add

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    Thanks ACR for paper and comments on it ["On the denudation of South Wales", Mem. Geol. Surv. G. B. 1 (1846): 297–335].

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    Sends copy of South America.

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    Discusses action of the sea.

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    Criticises ACR's views on sudden elevation of mountain chains.

Transcription

Down Farnborough Kent

Oct. 10th

Dear Sir

Having just read your excellent memoir on Denudation, I have taken the liberty to send you a copy of my volume on S. America, finding that we have discussed some related questions.— I wish I had profited by your memoir before publishing my volume.— I see that we entirely agree on the sea's great power compared with ordinary alluvial action, & likewise on the frequency of grand oscillations of level & on several other points. If you had time to read parts of my volume, I should much like to discuss with you many cases, such as my notion of subsidence being necessary for the formation of high sea-cliffs, as inferred from the nature of the sea's bottom off them, likewise the horizontal elevation of the Cordillera, as inferred from the sloping gravel fringes in the valleys —on the non-horizontality of lines of escarpments round old bays, &c &c—

I grieve to see how diametrically opposite our views are (I being a follower of Lyell) on the probability of great & sudden elevations of mountain-chains: I cannot but think, that you would have estimated existing forces, as more than “petty” & entertained some doubt about their being “conflicting” had you inspected with your own eyes the wide area of recently elevated & similarly affected districts in S. America. There is much which I could say on this head, but I will not intrude on you. May I ask, whether you do not admit Mr Hopkin's views of mountain-chains being the subordinate effects of fractures consequent on changes of level in the surrounding areas; & does not all the evidence, which we possess, tend to show that widely-extended elevations are slow, & may we not infer from this that the formation of mountain-chains is likewise probably slow.— I cannot see any difficulty, after a line of fracture has been once formed, in fluidifyed rock being pumped in by as many strokes, as it is pumped out in a common volcano, & yet producing a symmetrical effect.—

But I much fear that I have cause to apologise for having written at such unreasonable length: the interest excited in me by your Memoir, must plead my excuse, & trusting that you will forgive the liberty I have taken | I remain, dear Sir | Yours faithfully | C. Darwin

    Footnotes Add

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    f1 1008.f1
    Ramsay 1846.
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    f2 1008.f2
    See South America, pp. 25–6, and letter to Charles Lyell, [3 October 1846], n. 3.
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    f3 1008.f3
    CD believed that gravel terraces along the valleys of the Cordillera were marine deposits laid down as the land was gradually elevated (South America, pp. 62–7).
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    f4 1008.f4
    CD believed that the non-horizontal inclination of step-like terraces along the valleys of Coquimbo and Guasco was due to the elevation of land around bays (South America, pp. 41–6).
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    f5 1008.f5
    See letter to Charles Lyell, [3 October 1846], especially n. 6.
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    f6 1008.f6
    Hopkins 1838. See letter to Charles Lyell, [3 October 1846], n. 7.
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