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Letter 1162

Darwin, C. R. to Phillips, John

7 Mar [1848]

    Summary Add

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    JP's reference was clear, but seems to be different from the case cited by W. Hopkins about erratic conglomerate boulders. Asks for more details on the latter. CD does not think much of Hopkins' paper ["Elevation and denudation of the district of the lakes of Cumberland and Westmorland", Q. J. Geol. Soc. Lond. 4 (1848): 70–98].

Transcription

Down Farnborough Kent

March 7th

My dear Phillips

Will you forgive me troubling you once again. Your reference guided me to the exact case in point; but the fact referred to by Mr Hopkins in last Geolog. Journal seems different. He speaks of a very peculiar conglomerate (p. 98) from near Kirkby Stephen carried from the “depths of the vale of Eden over the heights of Stainmoor”. Where have you described this case, & will you be so very kind as to give me a few explanations. About what height is Stainmoor? Does he mean, that the conglomerate=boulders have been carried over Stainmoor, without remaining on it, & if so are they now deposited at a level above the vale of Eden.— Is Stainmoor a very long chain, (how long?) & is that the reason he concludes that these boulders have crossed it, instead of having gone round either end.—

I cannot find Stainmoor in such maps as I have, & as you will perceive, I am in a complete jumble on the subject. Are the conglomerate boulders rounded or quite angular? Hopkins throws from some reflected quarter some doubt about the identification of the conglomerate; if you have no doubt, I shd have none.—

I cannot say that I think much of this paper of Hopkins'

Believe me | Very sincerely Yours | C. Darwin

Can you remember whether the highest Slate-boulders were more worn, than those transported to a lesser height?

    Footnotes Add

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    f1 1162.f1
    Phillips had apparently sent CD a reference to Phillips 1835. See letter to John Phillips, [12? March 1848], in which CD stated he had found the reference he wanted in Phillips 1837–9.
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    f2 1162.f2
    Hopkins 1848, originally read in 1842, was published as a postponed paper in the Quarterly Journal of the Geological Society of London.
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    f3 1162.f3
    In ‘On the transportal of erratic boulders’ (Collected papers 1: 218), CD stated the case as follows: The conglomerate alluded to by Mr. Hopkins has been transported from the bottom of the valley of the Eden, where the rock lies in situ at the height of 500 feet above the level of the sea, to and over the pass of Stainmoor at the height of 1400 feet: therefore the boulders now lie 900 feet above their original position.
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    f4 1162.f4
    Boulders transported by icebergs would be angular, whereas if they were transported by coast-ice, as CD believed, they would be worn from repeated exposure to shore-line sea action (Collected papers 1: 221).
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    f5 1162.f5
    CD's question evidently was not answered by Phillips, because it reappeared unaltered in his paper (Collected papers 1: 223): It would be interesting to ascertain whether those [slate] boulders which now stand highest above the parent rock are more worn than those at a lower level, which latter I believe to have been dropped during the long-continued buoying-up process.
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