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Letter 2902

Lyell, Charles to Darwin, C. R.

[before 20 Nov 1860]

    Summary Add

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    Discusses the possibility of a land-bridge connecting Biscay with Ireland and the consequent occurrence in southern Ireland of Asturian plants which are absent from England.

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    Asks if Hooker or anyone has criticised Edward Forbes' botanical migration of five floras in the British Isles ["On the connexion between the distribution of existing fauna and flora of the British Isles, and the geological changes which have affected their area", Mem. Geol. Surv. G. B. 1 (1846): 336–432].

Transcription

was ever returned.

I suspect that the Scandinavian flora was the first, then the Germanic & that the other subfloras got in by various geographical opportunities after the era of submergence or floating ice & when the larger part or the whole area within the 100 fathom line was land dry—

If you refer to DelaBeche's map Geological Researches p. 190 or Trimmer Quart. Journ. G. S. p. 293 vol. 9. see maps you will see that a low plain of land skirting the bay of Biscay & France & joining Ireland would when all within the 100 fathom line was dry land allow the Asturian plants to reach Ireland & if this happened when the emeral isle was nearly or quite separated from England it might explain why said southern species never got into England.

Have you read Jamieson of Ellon in our last Quarterly Journal. 1860 p 349 &c. His 5 periods at p 370 can be made to square pretty well with Trimmers sketch maps above referred to. I shall give I think DelaBeches 100 fathom map, & Trimmer's submergence map—   But I am not prepared to give a third map but shall say that things were nearly restored to the status quo ante glacier after which came minor oscillations of level. What immense periods these within the glacial episode so brief a portion of the pleiocene!

Has Hooker or any one ever criticized E. Forbes' Botanical migrations of his 5 floras in British Isles? I have not heard whether J. Hooker is returned from Syria.

Phillips does not appear to me in glancing at his chapters to have taken hold strongly of any subject such as the age of the Amiens man or Natural Selection. He gives Sedgwick & others as authorities. In regard to progressive development he seems more cautious than formerly. Has he discovered that that theory tends in favour of transmutation!

    Footnotes Add

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    f1 2902.f1
    Dated by the relationship to the letter to Charles Lyell, 20 November [1860].
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    f2 2902.f2
    De la Beche 1834, p. 190. The map indicates the position of the 100-fathom line in the seas surrounding Britain. CD's annotated copy of the work is in the Darwin Library--CUL.
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    f3 2902.f3
    Trimmer 1853. The plate facing p. 293 includes sketch maps `illustrating the changes in the distribution of land and sea during the Pleistocene epoch'.
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    f4 2902.f4
    Lyell refers to the plants of the ancient province of Asturias in northern Spain. The presence of a few Spanish plants, chiefly heaths and saxifrages, in Ireland was an anomaly in the explanation of geographical distribution. See nn. 6 and 7, below.
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    f5 2902.f5
    Jamieson 1860.
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    f6 2902.f6
    Jamieson 1860, pp. 370--1. The text gives a synopsis of five possible stages in the `Pleistocene history of Scotland', accounting for the accumulation of drift and gravel deposits.
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    f7 2902.f7
    Lyell was studying the relationship between changes in the flora and fauna of Britain and geological changes in the level of the land during the Pleistocene period for his work on the antiquity of man. The maps and the possible configuration of Europe since the Pliocene were subsequently discussed in C. Lyell 1863, pp. 273--80. Lyell also published a map of his own illustrating the effects of `a downward movement of a hundred fathoms, or 600 English feet, supposed to have been uniform over the whole of the British Isles' (C. Lyell 1863, pp. 275, 278). Lyell was attempting to explain the non-uniform distribution of European species across the British Isles: he accepted the validity of Edward Forbes's hypothesis that organisms had migrated from Spain to Ireland over former land-bridges (C. Lyell 1863, pp. 283--4).
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    f8 2902.f8
    CD had often discussed Forbes's proposal of successive waves of plants and animals spreading throughout the British Isles from other parts of Europe during the Pleistocene period (see E. Forbes 1846) with Lyell, Joseph Dalton Hooker, and Hewett Cottrell Watson. See Correspondence vols. 4, 5, and 6. For CD's reply, see the following letter.
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    f9 2902.f9
    See letter to J. D. Hooker, 21 November [1860].
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    f10 2902.f10
    Phillips 1860, in which John Phillips addressed the question of the origin of life on earth. Phillips discussed the human artefacts found at Amiens, France, on pp. 48--50, and natural selection on pp. 200--4. CD's copy of the book is in the Darwin Library--CUL.
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    f11 2902.f11
    Phillips cites Adam Sedgwick in Phillips 1860, pp. 191 and 203 n. 1.
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