Some geologists (especially H. T. De la Beche) doubt boulders have really been carried above their parent rock, but rather thought they were left behind as a result of denudation. Asks JP's view of this, which he can quote. Supposes he will be well abused for his paper, but is resolved "not to show a white feather".
Down Farnborough Kent
My dear Phillips
It is in honest truth, a piece of impudence on my part to trouble you, I believe now for the fourth time on the same subject, but I do want your help much.—
Talking with some of our geologists & especially Sir H. Delabeche, I see that they are inclined to doubt whether in any cases the boulders have really been carried above their parent rocks, for they think that the strata whence they were derived, may have been within the erratic period prolonged to some other distant place up to the level of the blocks, & subsequently entirely denuded, thus.
This strikes me as a very bold view: can you give me any opinion on it, which I could quote on your authority. Are the strata of the red Conglomerate, (whence the boulders on Stainmoor have been derived) only gently inclined, for if so, an immense horizontal extension would be necessary to bring them up the 900 feet..—
When the parent rock is a hypogene formation, the whole solid mass on this view must have been denuded to that exact number of feet, which expresses the difference in height between the boulders & such parent rock. I think almost any theory would be more probable than such a view.—
I really shd be extremely obliged for one sentence to give on your authority, if you think as I am inclined to do on this head.—
I confess that I thought the notion here given viz of denudation so improbable, that I shd not have noticed it, had I not found that others looked at it differently.— I believe I shall get well abused for my paper & not make single convert to my own view, but I am resolved not to show a white feather & bring it out.
Ever yours most truly | C. Darwin
Will you send me a line soon, as my Paper is to be read at the next meeting, for which do you thank Heaven, as it must save you more notes.
- f1 1170.f1Dated from the reference to CD's paper, ‘On the transportal of erratic boulders’ (Collected papers 1: 218–27), which was read to the Geological Society of London on 19 April 1848. The dates are those of the two Fridays falling between the meetings of 5 April and 19 April.
- f2 1170.f2Henry Thomas De la Beche's view is discussed in CD's paper. Phillips is cited as having given CD conclusive reasons why De la Beche's view was ‘quite inadmissible’ as an explanation of the erratic boulders at Stainmoor (Collected papers 1: 219).