Ɛpsilon

From T. M. Reade   18 February 1878

Park Corner, | Blundellsands, | Liverpool.

Feby 18th 1878

My dear Sir

In pursuing the line of thought commenced in my address on Geological Time I have been led to compose a paper Entitled “Limestone as a function of Geological Time”. In which I attempt to show that the argument against calculations of the age of the Earth from the rate of denudation taking place now, founded upon presumably greater denudation in early ages, loses much of its force when we investigate the rate of formation of limestone deposits— It is impossible here to give you an outline of my line of reasoning but one question arises out of it in which perhaps you can aid me if your time is not too much occupied. It is this— If the rate of formation of limestone beds was greater in early ages it would involve a greater abundance of life in the ocean either Forameniferal Coral or Molluscan.1 This again involves an additional supply of food suitable to such life— Can you imagine any conditions in which this extra food supply would be provided? If so what?

Although I am led by other considerations to the conclusion that this carbonate of lime producing life was not more abundant in nature in former periods than now I should very much like to hear if you have any suggestion to make on the food question—

My paper controverting Sir Wm. Thomsons views—ie calculations of the age of the Earth from the increase of heat downwards—will I expect shortly appear in the Geological Magazine as I have just corrected the proof for that Journal.2

I remain dear Sir | Yours faithfully | T. Mellard Reade

Chas Darwin Es LLD.

1
In Reade’s 1876 presidential address to the Liverpool Geological Society, ‘On geological time’ (Reade 1876), Reade had estimated the age of the earth at 526 million years based on an analysis of the rates of erosion and sedimentation of the earth’s crust. CD’s copy is in the Darwin Pamphlet Collection–CUL; see also Correspondence vol. 25, letter to T. M. Reade, 9 February 1877. Reade’s paper ‘Limestone as an index of geological time’ was communicated to the Royal Society of London in January 1879; it concluded, ‘the elimination of the calcareous matter contained in the sedimentary crust of the earth must have occupied at least 600 millions of years’ (Reade 1879, p. 282). Limestone is any crystalline form of calcium carbonate (carbonate of lime) and is composed of the skeletal remains of forams (Foraminifera, a class of unicellular marine protozoans), corals, and molluscs.
2
Reade’s paper ‘The age of the world as viewed by the geologist and the mathematician’ (Reade 1878) examined objections to the estimate of William Thomson (later Lord Kelvin), based on the cooling of the earth’s surface, that it was improbable that the earth was habitable more than 100 million years ago. For more on Reade’s calculations, see Burchfield 1990, pp. 98–100.

Please cite as “DCP-LETT-11365,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-11365