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Darwin Correspondence Project

From A. C. Ramsay   6 January 1859

St Andrews

6 Jany 1859

My dear Sir

I am glad my notes were of real use to you.1 I shall get the list of thicknesses finished as soon as the press of present work is over with me.

You will receive as soon as or immediately after this some section I made across Anglesey in one of which near the middle of the sheet there is a fault affecting the Carboniferous and Permian rocks somewhat of the kind you want. It is not however planed straight across. Nevertheless to a geological mind at all events it is equally good for the purpose. The scale is true vertically & horizontally. Some letterpress accompanies it in part of which there is a brief notice of the fault. I know another fault far more astounding in Merionethshire.2

It is thus

NW SE f f 3 2 1 2 3 2 1

1 Llandeilo flags 2 Bedded felspathic trap, 3 Lingula flags. There is no mistake about the identity of the beds. The fault marked f is a down throw on the N.W. of about 12000 feet! I have been over the ground often. It is Selwyns work & I believe it. Selwyn was long with us & is now Director of the Geological Survey of Victoria3

Ever siny | Andw C Ramsay

There are scores of minor faults in the Oolites shaved quite flat across, many of them of several 100 feet. Ditto in the New Red Sandstone, and though unproved in the Miners sense of the term, they are equally satisfactory to you or I. The South Staffordshire coal field would scarcely be exposed at the surface but for faults

W N Red & Permian f Coal Measures E N Red & Permian f

f faults. downthrows to E. & W. But for them the Coal Measures would probably still be under New Red. There has been a denudation on a kind of average level & hence they are exposed.

Ever Siny | Andw C Ramsay

CD annotations

Top of first page: ‘Faults’ brown crayon, circled brown crayon; ‘22’4 brown crayon

Footnotes

See letter from A. C. Ramsay, 29 December 1858.
CD cited Ramsay’s findings on faults in the strata of Anglesey and Merionethshire in Origin, p. 285, noting that as a result of denudation, thousands of feet of sedimentary formations had been removed. CD sought such instances as evidence of the long span of time that must have elapsed since the formations were laid down and the present geological features of the earth were produced.
Alfred Richard Cecil Selwyn had worked on the Geological Survey with Ramsay in Wales before becoming director of the Geological Survey of Victoria, Australia, in 1852.
The number of CD’s portfolio of notes on palaeontology and extinction.

Summary

Responds to CD’s queries concerning faults; is sending sections of the kind he wants. The Merionethshire fault with a downthrow of 12000ft. [See Origin, p. 285.]

Letter details

Letter no.
DCP-LETT-2398
From
Andrew Crombie Ramsay
To
Charles Robert Darwin
Sent from
St Andrews
Source of text
DAR 205.9: 399
Physical description
4pp †

Please cite as

Darwin Correspondence Project, “Letter no. 2398,” accessed on 18 July 2019, https://www.darwinproject.ac.uk/letter/DCP-LETT-2398.xml

Also published in The Correspondence of Charles Darwin, vol. 7

letter