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Letter 559

Malcolmson, J. G. to Darwin, C. R.

[after 7 Oct 1839]

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    Comments on the discussion of erratic blocks in Journal of researches [pp. 619, 621–2].


of which a copy is in the Geol. Society Library is not quite expressed by what is said at the bottom of this page; and certainly Jameson's notice is imperfect.— P. 619 The shores of the Tertiary sea of the Jura is shown in beautiful models of these mountains made by one of Agassiz' pupils, of which one was made (Qy sent?) for the Geol. Society. This young man showed me fossiliferous rocks bored by pholades that skirt its edge such as you see in coral islands, &c. He had traced in great detail the shores of this ancient sea, but I think had not published This would be of importance to your theory.

P 621 Agassiz describes most correctly the phenomena near Neuchatel, but they did not seem to me sufficient to prove the arrangement in the order of sand, pebbles and blocks to be a general fact. I would explain them by the familiar fact, of small bodies when agitated with larger ones finding the bottom. They do not correspond to the facts everywhere to be observed in the diluvial Hills of the north of Scotland—there, pebbles, boulders and sand are mixed, or partially interstratified with each other, and often exhibit the laminated appearance of the older sandstones or the sand of the shore; and they sometimes contain large blocks which have come from the west.— gravel with sand.—

P 622. I found a little north of Pettycur in Fifeshire, the sandstones having grooved and polished surfaces exactly like the limestone of Neuchatel, except that there the smooth way in which the Neritinæ are cut across makes it more striking. The grooves are in the same direction as on Corstorphine Hill, and the corners of the strata are rounded off, and part of the upper has been removed, and the inferior is polished. This I believe was not discovered previous to my visit in Feby, as Dr Anderson told me that he doubted the facts mentioned by Hall, nothing of the kind having been met with in Fife regarding the geology of which he had just finished a detailed account.—

The passage of the blocks in Scotland from the west; and the drift extending into all the valleys can hardly be explained by the theory of glaciers—or rather I do not see how it is to be applied to the cases with which I am most familiar.

    Footnotes Add

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    f1 559.f1
    Dated on the assumption that Malcolmson received and read the Journal of researches soon after he wrote his letter of 7 October 1839, in which he said that he was expecting it daily.
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    f2 559.f2
    The notes refer to the pages in the Journal of researches in which CD states his theory of erratic boulders and discusses Agassiz's views of the glaciers and erratic boulders of Switzerland. The subject of Malcolmson's comment is CD's footnote on p. 617, in which he refers to p. 215 of an article by Jean de Charpentier in the Edinburgh New Philosophical Journal 21 (1836): 210–20. Robert Jameson was the editor of the Edinburgh New Philosophical Journal.
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    f3 559.f3
    CD's explanation of the Jura blocks was based on the assumption that an arm of the sea once extended between the Jura and the Alps.
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    f4 559.f4
    J. Anderson 1841.
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