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From J. W. Judd   15 November 1876

Royal School of Mines. | Jermyn Street | S.W.

15th. Novr. 1876.

Dear Sir,

I write to thank you for your kind consideration in sending me copies of the new editions of your “Coral Reefs” and “Geological Observations”—which I assure you that I shall very greatly prize as coming from yourself.1

Greatly as I value—in common with all students of Geology—the revised memoir containing the exposition of your beautiful Theory of Coral Reefs, yet (considering that this theory is now so universally accepted) I attach even higher importance to the republication of your “Geological Observations”. The latter work has, in my own case, proved to be so full of instruction and suggestiveness, that it has been a source of frequent regret with me to find certain of its teachings treated with so much neglect,—a result which I can only attribute to the work being, on account of its scarcity, so little known to many writers on geology at the present day.

In travelling in the Lipari and Ponza Islands and in Hungary, I have felt my conviction strengthened at almost every step, in the truth of your explanation as to the origin of the banded structure of lavas, and the important bearing these have upon the theory of the cause of foliations.2

I may add that I am engaged at present in a careful study of thin sections of these banded lavas from all parts of the globe, by the aid of the microscope, & I can fully confirm your conclusion, as to the separation of minerals of distinct species into well-marked folia, in the lavas of Ascension and of many other volcanic districts.3

I am sure you will pardon me for entering at such length into this question, and will permit me to express my gratitude for the instruction which these and your other works have afforded me

I am, Yours very faithfully, | John W. Judd

C. Darwin Esq.

1
Judd was an admirer of the first edition of Volcanic islands (Geological observations on the volcanic islands, visited during the voyage of HMS Beagle; see Correspondence vol. 22, letter from Charles Lyell, 25 September 1874). Second editions of Coral reefs and Geological observations were published in 1874 and 1876 respectively. Geological observations 2d ed. comprised new editions of Volcanic islands and South America in a single volume.
2
See Geological observations 2d ed., pp. 464–9. CD argued that foliation in crystalline schists (a metamorphic rock) was caused not by different types of mineral being deposited separately over time, but by minerals separating out when rock crystallised under pressure. (See also Judd’s critical introduction in Geological observations 3d ed., pp. 164, 275–6.) Judd discussed his geological investigation of Lipari and the Ponza Islands (Isole Ponziane) in Judd 1875; of Hungary in Judd 1876.
3
See Geological observations 2d ed., p. 469. Judd published generally on volcanoes, including images of sections of lavas, in Volcanoes: what they are and what they teach (Judd 1881).

Please cite as “DCP-LETT-10674,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-10674