WCP3693

Letter (WCP3693.3598)

[1]1

Waldron Edge, Duppas Hill, Croydon

July 2nd. 1879

Dear Sir2

Thanks for your papers which I have read with great interest. I have arrived at the conclusion that geological time may be much shorter than usually supposed. I think your estimate (& all estimates) of the average thickness of the sedimentary crust of the earth far too great. The maximum thickness of any formation now, may be often the total max. thickness deposited, because denudation is so unequal and some part of the area of greatest thickness will almost always remain protected by covering rocks. But this max. thickness is very great in proportion to average thickness, because the great mass of stratified rocks are shore deposits in bands or belts, and of constantly decreasing thickness as the belt is wider. I am glad [2] to see any view on this point (which I have already in MSS) entirely confirmed by Mr Geikies3lecture on "Geol[ogical]. Evolution" this day to hand. He also agrees in my often expressed view that the present continents & great oceans are (generally speaking) as old as the sedimentary rocks. Your view as to Limestone formation is opposed to this, but I think you overlook the enormous preponderance of limestone forming going on near shores— All corals are necessarily shore dwellers & they are the greatest of all limestone-formers, and thus keep up the supply of limestone notwithstanding that some is permanently stored up in the ocean abysses.

The calculations as to the quantity & rate of formation of limestone are I think too vague and doubful[sic] & have [3] much value.

Believe me | Yours very faithfully | Alfred R. Wallace [signature]

P.S. Your remarks on the doubtful value of Sir W. Thompsons’4 are very interesting & to some extent agree with my own. I had noted as an objection to "increase of heat" calculations that, as we know there are local causes sources of heat in the earth’s crust but do not know that there are any local sources of cold, we ought to take, not the mean but the minimum [one word crossed out, illegible] increase of temperature as that due to the general heat of the earth’s mass.

A.R.W. [signature]

1
"TMRI.W.2.2", while handwritten, is printed instead of in ARW’s usual cursive script, indicating that this was likely a later annotation.
2
This particular letter is, as we shall see, appears to be addressed to Thomas Mellard Reade, CE, FGS (1832 — 1909). A geologist, architect, and civil engineer, Reade worked in Liverpool, presided over the Liverpool Geological Society for three separate sessions and published many works, making extensive study of the geology of Lancashire. Wallace had also written to Reade on June 22nd, 1879 (whom he also addressed then as "Dear Sir") regarding Reade’s work on "Geological Time", discussed in this letter as well. Thus, the initials (see endnote 1) and content of the letter all suggest Reade as the most likely recipient.
3
Scottish geologist James Geikie, FRS (1839 — 1915). In 1882, Geikie became the Murchison professor of geology and mineralogy at the University of Edinburgh.
4
Irish mathematical physicist and engineer William Thomson, 1st Baron Kelvin OM, GCVO, PC, PRS, PRSE. Perhaps better known by his title, Lord Kelvin, he famously realised that there must be a lower limit to temperature, absolute zero. The units of absolute temperature, "Kelvins", bear his name still today.

Editorial information

Status: Draft transcription [Letter (WCP3693.3598)]

For more information about the transcriptions and metadata, see https://wallaceletters.myspecies.info/content/epsilon

Revision history

Transcribed by Clerx, William [2012-08-16] Transcription checked by Catchpole, Caroline [2013-01-15]

Please cite as “WCP3693,” in Beccaloni, G. W. (ed.), Ɛpsilon: The Alfred Russel Wallace Collection accessed on 29 April 2024, https://epsilon.ac.uk/view/wallace/letters/WCP3693