From Charles Lyell   7 May 1860

53, Harley St. London. W.

May 7. 1860

My dear Darwin

I saw Salters spirifers, a very good proof of the fructifying nature of your indefinite modifiability principle.1 I also asked him if he did not think that Barrandes “primordial” (the Cambrian of Manual 5th. Edn. ) was getting more & more separated from Lower Silurian—2 He replied certainly— I am beginning to think the gap was enormous between them. And then there are the Huronian & Laurentian each with rippled sands 1000ds. of feet thick unconformable to the Potsdam or “primordial”.3 The latter I hear has just been found by Cassiano del Prado in some part of Spain.4

Suppose the gap as I begin to suspect to be as great as between Cretaceous & Eocene what a grand discovery the Cambrian type is—

On Wednesday May 16th. we expect a large meeting of the Geol. Socy in the hall in Burlington House when Lartet’s paper5 on contemporaneity of

AL incomplete

CD annotations

3.1 On … contemporaneity of 3.2] crossed brown crayon
Top of first page: ‘22’6 brown crayon
2
Joachim Barrande believed that the lower Silurian formations around Prague constituted a new system, which he named the ‘Primordial’. Comparable rocks in Britain were the subject of heated debate between Adam Sedgwick and Roderick Impey Murchison. Sedgwick insisted, like Barrande, that the formations were sufficiently distinct to merit a separate name (the ‘Cambrian’); Murchison, on the other hand, maintained that they were merely part of the lower Silurian. In his Manual of geology (C. Lyell 1855, pp. 452–5), Lyell had given his support to Sedgwick’s view. For a study of the debate, see Secord 1986.
3
Huronian and Laurentian formations, which were being actively studied by members of the Geological Survey of Canada at the time, were later identified as pre-Cambrian. See Zaslow 1975.
4
Casiano de Prado began a geological survey of Spain in 1848.
5
Édouard Amant Isidore Hippolyte Lartet’s excavations of flint-bearing sites helped to establish the contemporaneity of man and extinct animals (DSB). His paper ‘On the coexistence of man with certain extinct quadrupeds’ (Lartet 1860) was read at a meeting of the Geological Society on 16 May 1860. Leonard Horner, president of the society, contributed remarks that were printed with the paper.
6
The number of CD’s portfolio of notes on palaeontology and extinction.

Please cite as “DCP-LETT-2787,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-2787