Referee's report on paper by Daniel Sharpe ["On foliation and cleavage", Philos. Trans. R. Soc. Lond. 142 (1852): 445–62].
In my opinion M
With regard to M
Notwithstanding the foregoing objections, from the novelty &, as it appears to
me, importance of the subject, I am of decided opinion that M
Apologising for the length of this Report | I remain, Sir, Your obedient
servant | Charles Darwin
To the Chairman of | the Committee of Papers.
P.S. | The author ought to state whether his bearings have been corrected for variation; & a scale of colours should appear on the map, together with an explanation of the several lines used.
- f1 840.f1Sharpe 1852, which Daniel Sharpe had told CD he was writing for the Royal Society (letter to Daniel Sharpe, 16 October ). The paper had been read at meetings of the Royal Society on 12 and 19 February 1852 (Abstracts of the papers communicated to the Royal Society of London 6 (1850–4): 152).
- f2 840.f2John MacCulloch, physician and geologist, had been commissioned in 1826 to prepare a geological map of Scotland.
- f3 840.f3CD cited Gardner 1840, Schomburgk 1842, and Humboldt 1814–29 in South America, p. 141. No location is given for Alexander von Humboldt's observation, but see Humboldt 1814–29, 4: 384–5, and 5: 394–8. CD's copy of this work is in the Darwin Library–CUL.
- f4 840.f4In his explanation of the map (Sharpe 1852, pp. 460–1), Sharpe stated that: ‘The strike or direction of the foliation and cleavage across the surface is indicated by black lines … The dotted lines show the direction supposed to be followed, in unexamined districts, by the lines just explained. All the lines are laid down on the Map with more continuity and regularity than really exist; this error can only be fully corrected by a minute examination of the whole country.’
- f5 840.f5The term ‘arches’ appears in the published version, but ‘lines of elevation’ has been omitted. Theoretical reconstructions are illustrated on Plate XXIII.
- f6 840.f6Another report recommending that Sharpe's paper be published, dated 4 March 1852, was written by Adam Sedgwick. Sedgwick observed: ‘If the cleavage planes of the unequivocably stratified slates be parallel to the foliations of the crystalline slates, it seems to follow, of absolute necessity, that the foliations must themselves be due, not to planes of original & mechanical deposition, but to a subsequent crystalline action. This is the fundamental point of the paper; & the conclusion agrees with the views published by M
rDarwin’ (Royal Society (RR2: 224)).
- f7 840.f7In his explanation of the map, Sharpe included a note detailing how the variation in the measurements of strike was corrected. He also explained the various lines used on the map. The map itself bears a key relating colour to rock type and this is also spelled out in the explanatory text (Sharpe 1852, pp. 460–1).