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Darwin Correspondence Project

From William Hopkins   5 May 1846


May 5— 46

My dear Sir

The additional datum you sent to me yesterday is of no material service in your problem.1 If your observations were sufficient to establish a general regularity in the lamination over a sufficiently wide area, (and such I think appears to be your conviction) we can scarcely resist the conclusion that the local irregularities in the laminated beds in the immediate neighbourhood of the granitic ridge (where alone I presume you found them) are due to the upheaval of that ridge. Allowing the validity of the conclusion, I should be disposed to attribute at least a considerable portion of the discordance between observed & calculated results to irregularities in the elevation of the ridge such as might arise for instance from violent lateral thrusts, the effects of which might be resisted by the flanks of the mass in an uncertain and irregular manner, and which might thus produce effects which it would be impossible to bring under the dominion of calculation. A good deal may safely be allowed to irregular action of this kind.

Let me again assure you that your problem has been no trouble to me. In a subject like Geology where it is impossible for any one to be equally acquainted with every branch of it, I hold it to be a duty to assist each other, and on that principle you will always find me ready to act.

Your’s very truly | W Hopkins


CD evidently responded promptly to the letter from William Hopkins, 27 April 1846. As South America, p. 159, makes clear, CD still hoped his alternative hypothesis had some basis.


South America: Geological observations on South America. Being the third part of the geology of the voyage of the Beagle, under the command of Capt. FitzRoy RN, during the years 1832 to 1836. By Charles Darwin. London: Smith, Elder & Co. 1846.


Discussion of CD’s geological problem, relating to elevation of laminated beds around a rising granitic ridge.

Letter details

Letter no.
William Hopkins
Charles Robert Darwin
Sent from
Source of text
DAR 39: 57–8
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 978,” accessed on 26 January 2020,

Also published in The Correspondence of Charles Darwin, vol. 3