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Darwin Correspondence Project

To A. C. Ramsay   7 April [1848]

Down Farnborough Kent

April 7th

Dear Ramsay

Would you be so kind as to inform me, as you will probably know, or perhaps would be so good as to look at the Ordnance Maps, what is the height of Moel Tryfan in Carenarvonshire situated in a line nearly between Snowdon & Caernarvon.1 This hill has been repeatedly mentioned, since Mr Trimmers important discovery2 & no two authors give the same height: in my notice on this hill, I give a very much less height than others & I cannot for the life of me remember on what authority, though I know I took some pains to ascertain.3 I shd be very much obliged for an answer pretty soon, if you can so far oblige me.

Yours sincerely | C. Darwin


CD sought this information for use in his paper, ‘On the transportal of erratic boulders’, read on 19 April 1848 (Collected papers 1: 218–27).
Joshua Trimmer discovered broken fragments of marine shells in diluvial sand and gravel ‘1000 ft above the level of the sea on the summit of Moel Tryfan’ (Trimmer 1831, p. 331). Referring to Trimmer’s discovery, CD stated that the beds which included the shells were undoubtedly ‘deposited in the ordinary manner under the sea’ (Collected papers 1: 223).
Trimmer had originally given the height as 1000 ft (see n. 2, above). In ‘Notes on the effects produced by the ancient glaciers of Caernarvonshire’ (Collected papers 1: 167), CD gave the height as 1192 ft, but he cited as his source Murchison 1839, 2: 528, where the height is given as 1692 ft. In ‘On the transportal of erratic boulders’, the height is recorded as 1392 ft (Collected papers 1: 219).


‘Ancient glaciers of Caernarvonshire’: Notes on the effects produced by the ancient glaciers of Caernarvonshire, and on the boulders transported by floating ice. By Charles Darwin. Philosophical Magazine 3d ser. 21 (1842): 180–8. [Shorter publications, pp. 140–7.]

Collected papers: The collected papers of Charles Darwin. Edited by Paul H. Barrett. 2 vols. Chicago and London: University of Chicago Press. 1977.

Murchison, Roderick Impey. 1839. The Silurian system, founded on geological researches in the counties of Salop, Hereford, Radnor, Montgomery, Caermarthen, Brecon, Pembroke, Monmouth, Gloucester, Worcester, and Stafford; with descriptions of the coal-fields and overlying formations. 2 pts. London. [Vols. 4,7]

Trimmer, Joshua. 1831. On the diluvial deposits of Caernarvonshire, between the Snowdon chain of hills and the Menai strait, and on the discovery of marine shells in diluvial sand and gravel on the summit of Moel Tryfane, near Caernarvon, 1000 ft above the level of the sea. [Read 8 June 1831.] Proceedings of the Geological Society of London 1 (1826–33): 331–2. [Vols. 4,9,11]


Asks ACR to establish height of Moel Tryfan in Caernarvonshire; "in my notice on this hill [""Ancient glaciers of Caernarvonshire"" (1842), Collected papers 1: 163–71] I give a very much less height than others". [See also another mention of the elevation of Moel Tryfan in "On the transportal of erratic boulders" (1848), Collected papers 1: 218–27.]

Letter details

Letter no.
Charles Robert Darwin
Andrew Crombie Ramsay
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Source of text
Imperial College of Science, Technology, and Medicine Archives
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 1168,” accessed on 1 December 2021,

Also published in The Correspondence of Charles Darwin, vol. 4