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Darwin Correspondence Project

To T. H. Huxley   27 January [1875]1

Down, | Beckenham, Kent. Railway Station | Orpington. S.E.R.

Jan 27

My dear Huxley

I have no suggestions to offer except about glacial phenomena, to which, if I were on the expedition, I should particularly attend.2 It would I think be important to choose a naturalist who has studied this subject.3 I have given my reasons for attending to certain points, as a better guide to any observer; but whether this is desirable I know not. The fact about the pebbles standing vertically rests on my own observations; & as far as I know has not been observed by others

I would suggest your instructing the Naturalist carefully to observe what organisms are found in any hot springs, and to ascertain carefully its temperature: I was astonished to find that the thermometer was forgotten by the Challenger Expedition at the Azores.4

Ever yours sincerely | Ch. Darwin

I hope that my suggestions are intelligible, but I cannot say much for their style—


(1) As a standard of comparison with the beds of detritus which are supposed to have been formed in England during the glacial period, it seems desirable that the deposits on Arctic shores, which would be exposed to the constant action of an open sea, were it not for the frequent presence of ice, should be carefully studied. It should be observed how large a proportion of the stones are angular or sub-angular, & whether they are approximately of equal size or very unequal. It might even be worth while to collect illustrative specimens. If there is reason to believe from lines of erosion or other evidence, that the land has been recently upraised, beds of detritus adjoining the shores should be studied with equal care under the same point of view.

(2) As no one has hitherto succeeded in pointing out clear distinctive marks by which it can be told whether a rocky surface has been ground & scored by glaciers or by floating coast-ice or by icebergs, the shores & any low promontory projecting into the sea ought to be examined during low water. If the land has been recently elevated, such observations would be particularly valuable if made on a hilly & rocky promontory. The size & depth of the scores should be noted & their direction; for instance whether in the case of a promontory, they extend almost horizontally & parallel to the present coast, or rise up its sloping flanks & cross in its straight lines its summit. Do icebergs or coast-ice wear the rocks into rounded bosses like those so commonly formed by glaciers? Does coast-ice ever leave erratic boulders perched in the summits of the rocks in sitû, or on narrow ledges along their sides?

(3). If almost level & thick fields of perpetual snow should be met with abutting against steep land, from which during the short summer streams of water descend, it would be desirable to observe whether small fragments of stone are thus carried to some distance over the frozen surface. In this case the general character, that is the depth, width & extension or length of the channels cut by the streams in the snow should be observed & the nature of any detritus in their beds. From the drifting of the snow during the winter it seems improbable that such streams would during the next summer deposit their detritus in the same channels as before; so that in the course of time detritus would tend to accumulate over a wide extent of the frozen surface and at different levels. Observations on this head would perhaps throw light on the origin of the interstratified beds of ice & of gravel containing the bones of mammals, which have been observed in Eschscholtz Bay & in N. Siberia.5 Light also would perhaps thus be thrown on the extensive beds of angular shingle which in some parts of England cover the surface of the land irrespective of its present outline, & which there is reason to believe was accumulated during the Glacial Period. In the beds of shingle just referred to, many elongated pebbles & angular fragments of rock are embedded in an almost vertical position; & this fact apparently indicates that the whole bed has sunk down in a slow & irregular manner. Such sinking would follow during the slow melting of buried snow at the close of the Glacial Period if the shingle had originally been deposited on its surface.


The year is established by the relationship between this letter and the letter from T. H. Huxley, 22 January 1875.
Huxley had asked CD for suggestions for the scientific manual for a planned polar expedition (letter from T. H. Huxley, 22 January 1875). The part on glacial observations was Thomas Rupert Jones ed. 1875, pp. 74–7, written by Andrew Crombie Ramsay and John Evans.
The naturalists appointed to the expedition were Henry Chichester Hart and Henry Wemyss Feilden.
See Thomas Rupert Jones ed. 1875, p. 66; this section was written by Joseph Dalton Hooker. The HMS Challenger expedition was an oceanic survey that took place between 1873 and 1876; since one of its main purposes was to measure ocean temperatures, it was well supplied with thermometers. The naturalists on the expedition visited the hot springs at San Miguel in the Azores in July 1873. See Tizard et al. 1885, pp. 176–7. No other reference has been found to their not having a thermometer; however, the visit to the hot springs was acknowledged to be ‘totally unscientific’ and ‘a few days of complete relaxation’, given the lack of time available (Thomson 1873, p. 402).
Eschscholtz Bay is in Alaska. On the finds of large animal carcases in Siberia and bones, horns, and hair in Eschscholtz Bay, see J. Richardson 1854, pp. 1–8.


Richardson, John. 1854. Vertebrals, including fossil mammals. In The zoology of the voyage of H.M.S. Herald, under the command of Captain Henry Kellett during the years 1845–51, edited by Edward Forbes. London: Lovell Reeve.


Sends suggestions for observations on glacial phenomena that might be made on the [Polar] expedition [of H. M. S. Alert and Discovery, 1875–6].

Letter details

Letter no.
Charles Robert Darwin
Thomas Henry Huxley
Sent from
Source of text
DAR 92: A48–53
Physical description
3pp, encl 4pp

Please cite as

Darwin Correspondence Project, “Letter no. 9831,” accessed on 4 June 2020,

Also published in The Correspondence of Charles Darwin, vol. 23