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Letter 4143

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

6 May 1863

    Summary Add

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    Glad CD likes his Presidential Address to Geological Society [1863].

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    Will continue the practice [of discussing the break in succession of strata].

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    Has devised a diagram showing number of genera and species in each geological formation and the number that pass from formation to formation.

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    Describes the glaciated terrain of S. Wales.

Transcription

DolauCothy, Llandielo

6 May 1863

My dear Sir

Having nothing to do I am so lazy that I have neglected for some days to answer your welcome letter. In truth I have been here now 4 weeks trying to coax myself by idleness into my usual health. I have I hope partially succeeded but not thoroughly as yet. The prescription is however pleasant, viz a lovely place, old & well beloved friends a good library including plenty of novels, some pretty girls, my wife & one of my daughters, good trout streams and a horse to ride on when I want it.

I am very glad that you approve of my address. I supposed that if properly treated the subject would be sure to interest you both as a geologist & a Zoologist. Sir Charles Lyell writes me that he hopes I will continue the subject precisely as I began it if I continue President. Such was my intention with possible additions in the summing up. Sir Charles wishes that experienced Surveyors all over the Continent would each do the same for their own Countries, but from what I have seen of Continental Surveys the mapping has not been done in sufficient detail to admit of it. Sella who reported to the Italian government on the Subject said to me that all the Continental surveys were done too rapidly. For years I have had a diagram which I used in my lectures, something like one that you suggest, but with a considerable difference, & I thought of using it in my next address if I can find time to correct it up to date.

It is like this

[DIAG HERE]

It shows the number of species in each formation, the number of genera, & also the number of genera & species that pass from one formation to another, & is very instructive.

Logan has a splendid Case in Canada of a cliff overlapped in the way you mention. All the rocks concerned in the question are Old Silurian &c. I have no doubt he will send you a copy of the book when published. I know of no positive case in England, but we have something like it too. ``Creeps'' are certainly often over the land.

You do me too much honour in supposing that I can give a satisfactory philosophical discussion on these & the other points you mention, but it must be done some day, & if I live & thrive perhaps I may try my hand at it.

Have you seen Geikie's new book on the Drift of Scotland? It seems excellent.

This South Welsh land is full of Scratched stones & boulders. When I mapped it 20 years ago I knew the erratics when I saw them but I had then never seen a glacier & was not up to the Scratched stones. There is a good field here still remaining for any one to work out in that way. For want of clear sections I cannot say whether the detritus is all or mostly iceberg work, or whether land ice did a deal of it. There are no mountains here, but all the country is hilly.

Ever sincly | Andrew C Ramsay

    Footnotes Add

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    f1 4143.f1
    Letter to A. C. Ramsay, 29 April [1863].
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    f2 4143.f2
    The references are to Ramsay's friends John and Elizabeth Johnes of Dolaucothy, Llandilo, Carmarthenshire, Wales, and their two daughters, Charlotte Anna Maria and Elizabeth (County families 1860--76; Geikie 1895, pp. 76, 278, 340). Ramsay and his wife Louisa had four daughters and one son (DNB).
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    f3 4143.f3
    See letter to A. C. Ramsay, 29 April [1863]. Ramsay gave his presidential address to the Geological Society of London on 20 February 1863, taking as his theme breaks in succession in the British Palaeozoic strata (Ramsay 1863). Ramsay concurred with CD's argument that the imperfection of the geological record explained the absence of transitional links between many species in successive geological formations (see Correspondence vol. 8, letter from A. C. Ramsay, 21 February 1860). In his address, Ramsay introduced the idea that the periods of time for which there was no stratigraphical evidence might be longer than the geological periods that were represented by stratified formations (see Geikie 1895, pp. 357--8).
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    f4 4143.f4
    Ramsay was president of the Geological Society from 1862 to 1864 (DNB). CD had also encouraged Ramsay to continue his discussion with reference to breaks in succession in other strata (see letter to A. C. Ramsay, 29 April [1863]). See also n. 7, below. Ramsay's presidential address for 1864 discussed breaks in succession in the British Mesozoic strata (Ramsay 1864).
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    f5 4143.f5
    Ramsay refers to the Italian geologist Quintino Sella (Sarjeant 1980--96).
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    f6 4143.f6
    Ramsay probably refers to the annual series of lectures that he delivered at the Royal School of Mines, where he was professor of geology.
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    f7 4143.f7
    In his letter to Ramsay of 29 April [1863], CD suggested that Ramsay publish a diagram of the physical breaks in the British geological record, indicating the percentage of fossils that continued to appear in the stratum above a break. Ramsay included tables showing the numbers and percentages of fossil species that passed from one formation to another in Mesozoic strata in his presidential address to the Geological Society in 1864 (Ramsay 1864).
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    f8 4143.f8
    The lines on the graph represent the number of genera and species found in each geological formation and (on the intersections with the vertical lines) the respective number surviving from each formation to the next. For clarity, the genera line has been depicted here as a grey line to distinguish it from the species line. The annotation of the graph is only complete with reference to the Devonian and Carboniferous formations. In the Devonian formation, for example, the number of species rises to a peak of 600 and the number of genera rises to a peak of 100. In passing from the Devonian to the Carboniferous, 50 genera and 10 species are common to both formations. The number of species common to two formations is invariably smaller than the number of genera because in the intervening period many species have become extinct, while different species of the same genera have arisen. Ramsay eventually chose a tabular rather than a diagrammatic format to represent changes in the occurrence of fossil genera and species between geological formations (Ramsay 1864).
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    f9 4143.f9
    The reference is to the Canadian geologist William Edmond Logan; the case referred to is described in [Logan] 1863, pp. 295--7. In his letter of 29 April [1863], CD suggested that Ramsay might discuss creeps (slow, more or less continuous movements of rocks under gravitational stresses), and asked: `why do we not often find, old sea-cliff overlapped?'
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    f10 4143.f10
    Ramsay refers to a report of the Geological Survey of Canada ([Logan] 1863) summarising the work of the survey since 1843. CD does not appear to have received a copy of this publication.
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    f11 4143.f11
    Geikie 1863. Archibald Geikie was a colleague of Ramsay's on the Geological Survey of Great Britain.
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    f12 4143.f12
    After joining the staff of the Geological Survey of Great Britain in 1841, Ramsay spent the first four years mapping the geology of South Wales (DNB). In the 1840s, the role of glaciation in shaping the landscape of Britain was only just beginning to be appreciated (see Davies 1969, pp. 266--316). Ramsay subsequently conducted fieldwork that used scratched stones and boulders as evidence of past glaciation (Ramsay 1855).
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