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Darwin Correspondence Project

To Archibald Geikie   30 December 1871

Down, | Beckenham, Kent.

Dec 30. 1871

My dear Sir

I am very much obliged for your valuable letter.1 I have been sending the enclosed paper to various parts of England, & I hope to get information.

If you could visit the old ploughed surfaces near Edinburgh, to which you allude, & make some observations they wd be of the greatest interest.

This case alone makes me doubt whether the worm-castings can be washed down a gentle slope, yet I cannot see how my observations on the slight downward flowing of recent castings can be incorrect. The plan which I am adopting & shall continue with old castings is to remove the earth below & above the hole through which the casting has been ejected; then to weigh the two halves & measure the angle of the slope; & ultimately to strike an average of the weights & angles.

With very sincere thanks for your letter, believe me | yours very truly | Ch. Darwin

Your case of the fort with the ridges running obliquely across the hill, with the lower parts most filled up, if you had been fully convinced of the generality of the case, wd. have been good evidence for me; though of course other agencies may have come into play besides the earth-worms.—

By odd chance I happened to notice the passage in Playfair about vegetable soil not long ago, & Ramsay likewise called my attention to it in your Edit. of Jukes—2

[Enclosure]

I have seen (some 45 years ago!) in North Wales land, showing by ridges & furrows that it had been ploughed apparently centuries ago.3 Do such exist in your neighbourhood; or can you find a field with ridges & furrows which has been laid down in grass for about half a century or more. In all such cases if the surface slopes I want much to learn whether the ridges & furrows run straight or obliquely down the slope, or transversely across it. In the former case it wd. be of the greatest service to me if you wd. observe whether the ridges & furrows are as distinct near the base of the slope as at its top. By far the best way to observe wd. be to stretch a string in 2 or 3 places from ridge to ridge & measure the depths of the furrow in the upper & in the lower part of the slope. If the ridges & furrows runs transversely across the slope, the only point to observe wd. be whether the two slopes of the ridges have become different to what they are in a recent stubble field.— In any field observed please to notice whether there are many worm-castings about.—

My object is to trace the manner of gradual obliteration of ridge & furrow in old pasture-land, as far as such obliteration is ever effected | C. Darwin

Footnotes

See letter from Archibald Geikie, 29 December 1871 and nn. 4 and 5. No letter has been found from Andrew Crombie Ramsay mentioning Geikie’s reference to John Playfair in his edition of Joseph Beete Jukes’s Student’s manual of geology (Jukes 1872).

Bibliography

Jukes, Joseph Beete. 1872. The student’s manual of geology. 3d edition. Edited by Archibald Geikie. Edinburgh: A. and C. Black.

Summary

Is obliged for valuable letter [see 8123] and encloses queries about the manner of gradual obliteration of ridges or furrows in old pasture lands in various parts of England.

Gives details of his experiment to test his observations of the downward flow of worm-casts.

Refers to [Lyon] Playfair, [A. C.] Ramsay, and AG’s edition of [J. B.] Jukes, [A student’s manual of geology, 3d ed., 1872].

Letter details

Letter no.
DCP-LETT-8125F
From
Charles Robert Darwin
To
Archibald Geikie
Sent from
Down
Source of text
DAR 185: 133
Physical description
4pp, encl LS(A) 1p

Please cite as

Darwin Correspondence Project, “Letter no. 8125F,” accessed on 17 June 2021, https://www.darwinproject.ac.uk/letter/DCP-LETT-8125F.xml

Also published in The Correspondence of Charles Darwin, vol. 19

letter