# To Andrew Crombie Ramsay   29 April [1863]1

at Revd. C. Langton’s | Hartfield | Tonbridge Wells2

April 29th

Dear Ramsay

I am extremely much obliged to you for sending me your Address.3 I shd. think it would interest geologists; to me, as you may suppose, it is deeply interesting. Such discussions are the real method of discussing the modification of Species.4 It is a great problem for the future how the geological record is so imperfect.—5 I hope that you may be induced to go on with the series of Breaks.—6 If you do, at the end, could you not give a table or diagram with names of Formations; & the Physical Breaks shown by thicker or thinner black lines—or interrupted lines.—or longer or shorter lines to show extent or degree of break & creeps. How grand it would be, if you could add to each physical Break, the percentage of Fossils which pass upwards; thus7

Wenlock $\frac{13}{60}$ = Upper Llandovery $\frac{20}{28}$ = Lower Llandover $\frac{16}{500}$ = .32 Caradoc

(Thickness of formation?)

I wish there were data to say how many thousand feet of fine sediment may be deposited with no change of species from top to bottom; or better still if we could say that after so many thousand feet, without a Break, some few, (some 2 or 3 per cent) of the species at base were represented by analogous species at top. But migration &c render this hope or wish Utopian.— I was glad to see you snub our good friend Huxley’s geology: I was horrified at his view; it might to certain extent be tenable for strictly land productions.—8

I wish you would take opportunity & discuss “creeps” or overlappings of Formations.9 Are the “creeps” over the land; & if so, why do we not often find, old sea-cliff overlapped?

[DIAG HERE]

Why not old river-beds &c overlapped? Are our sections not perfect enough to show these cases? Or have our chief great formations been all formed at mouths of great rivers, where estuary land is low? Or do large spaces of bottom of sea remain for ages uncovered, & are these sea-beds crept over? How with our Coal measures, & new Red Sandstone with Foot-prints; does a fault separate the sinking area from the stationary or rising land whence sediment is derived? Do give us a philosophical discussion on this whole subject.—

With sincere thanks for the great interest derived from your address, believe me Dear Ramsay | Your’s very sincerely | Ch. Darwin

Excuse untidy paper.—

## Footnotes

The year is established by the reference to Ramsay 1863 (see n. 3, below).
Charles Langton, widower of Emma Darwin’s sister Charlotte, lived at Hartfield Grove, Hartfield, Sussex. According to Emma Darwin’s diary (DAR 242), the Darwins stayed at Hartfield between 27 April and 6 May 1863.
Ramsay delivered his presidential address to the Geological Society of London on 20 February 1863; it was printed in the Quarterly Journal of the Geological Society (Ramsay 1863).
In Ramsay 1863, the author related British palaeozoic stratigraphy to the fossils contained in the strata, mentioning several times CD’s views on modified descent (ibid., pp. xlviii, l, lii). Ramsay speculated (ibid., p. l): Supposing, therefore, Mr. Darwin’s hypothesis to be correct, it may be asked whether, under the changing conditions coincident with disturbance of strata, there may not have been influences at work that entailed a more rapid development of new species out of old, and of old species into new genera, than those that existed during an epoch when the conditions in a given area remained completely unchanged.
In his address, Ramsay discussed the incompleteness of the geological record (see, for example, Ramsay 1863, pp. l and lii). In his conclusion (ibid., p. lii), he stated: Furthermore, many considerations, partly stated, lead me to suspect that we must look to the lapse of time unrepresented by strata, as the chief cause, or, rather, as the necessary accompaniment, of the influences that produced the great difference in species between any two formations one of which lies unconformably on the other, whether we adopt the old view of gradual extinction and replacement by special creation, or Mr. Darwin’s more philosophical argument of descent with modification.
Ramsay’s address was entitled ‘Breaks in succession of the British Palæozoic strata’ (Ramsay 1863). He defined ‘breaks in succession’ (ibid., p. xxxvi) as: physical interruptions in stratification marked by the unconformity of an upper formation to one immediately underlying it, or, when such visible unconformity is wanting, by a sudden change in the fossils characteristic of the underlying and overlying formations. At the end of his address, Ramsay noted that he had intended to apply similar evidence to breaks in succession in the ‘Secondary and Tertiary formations’ (Ramsay 1863, p. lii).
CD’s fractions in the diagram demonstrate the number of species that still survived in the overlying bed. For instance, of the approximately 500 species contained in the Caradoc sandstone, 16 were also found in the Lower Llandovery rocks; 3.2 per cent, therefore, ‘pass upwards’. See Ramsay 1863, pp. xxxix–xlii, for a discussion of the South Wales strata that CD depicted and their fossils. Ramsay did not provide a diagram, but did include a table listing the principal species. In the text he stressed the significance of the ‘doctrine of per-centages common to two or more formations’, noting that it had destroyed the notions of catastrophism, and of life in any given period being suddenly extinguished ‘by a distinct act of omnipotence’ to be replaced by a ‘universal new creation when the succeeding deposits began’ (Ramsay 1863, p. xlix).
In his address (Ramsay 1863, pp. li–lii), Ramsay criticised Thomas Henry Huxley’s hypothesis that different fossil formations lying at great distances from one another might have existed at the same time owing to prolonged migration of species between continents: ‘the process of transmission of a group from one area to another might be prolonged indefinitely, so that … a Silurian, a Devonian, and a Carboniferous fauna might all exist in different areas at the same time’. Huxley made his comments in his anniversary address to the Geological Society on 21 February 1862 (T. H. Huxley 1862a, p. xlvi). See also Correspondence vol. 10, letters to T. H. Huxley, 10 May [1862], 7 December [1862], and 18 December [1862].
Ramsay referred to ‘creeps’ on one occasion during his address, noting that in ‘Pembrokeshire the limestone does creep across the Old Red Sandstone in a manner suggestive of overlap rather than of break and unconformity’ (Ramsay 1863, p. xliii).

## Summary

Interested in ACR’s Presidential Address [Q. J. Geol. Soc. Lond. 19 (1863): xxix–lii] on the breaks in succession (of formations). Hopes ACR will provide a diagram of breaks, with the percentage of fossils that "pass upwards", i.e., continue to appear.

Horrified at Huxley’s geology.

Wishes ACR would discuss "creeps".

## Letter details

Letter no.
DCP-LETT-4131
From
Charles Robert Darwin
To
Andrew Crombie Ramsay
Sent from
Charles Langton, Hartfield
Source of text
DAR 261 (DH/MS 9: 1)
Physical description
5pp