The red notebook of Charles Darwin / edited, with an introduction and notes by Sandra Herbert.

  • Charles Darwin
Date:
1980
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Licence: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

Credit: The red notebook of Charles Darwin / edited, with an introduction and notes by Sandra Herbert. Source: Wellcome Collection.

    113/184 (page 99)
    NOTES 99 so as to form a tuff. ... Although the pumiceous conglomerate, as I shall venture to call this rock, is seen in every part of the island, yet at Monte Vico. .. we observe intermixed with it huge blocks of trachyte...In a footnote on this page, which Darwin heavily scored in his own copy of the work, Daubeny stated that other geologists had identified the predominate rock at Ischia as an earthy variety of trachyte. Sir George Steuart Mackenzie, F.R.S. (1780-1848), mineralogist, as quoted in Daubeny, Volcanos, p. 221 : In many places [in Iceland], [Sir G. Mackenzie] says, an extensive stratum of volcanic matter has been heaved up into large bubbles or blisters, varying from a few feet to forty or fifty in diameter. The original reference is to George Steuart Mackenzie, Travels in the Island of Iceland. . .1810 (Edinburgh 1811), pp. 389-390. As quoted in Daubeny, Voléanos^ p. 313: In Sumatra, Marsden has described four [volcanos] as existing, but the following are all the particulars known concerning them: Lava has been seen to ñow from a considerable volcano near Priamang, but the only volcano this observer had an opportunity of visiting, opened on the side of a mountain about 20 miles inland of Bencoolen, one fourth way from the top, so far as he could judge.. . . He never observed any connexion between the state of the mountain and the earthquake, but it was stated to him, that a few years before his arrival it was remarked to send forth flame during an earthquake, which it does not usually do. The inhabitants are however alarmed, when these vents all remain tranquil for a considerable time together, as they find by experience, that they then become more liable to earthquakes. The original reference is to William Marsden, The History of Sumatra (3rd ed.; London, 1811), pp. 29-30. Alexandre Moreau de Jonnès (1778-1870), French economist and natural historian as cited in Daubeny, Volcanos, p. 334: The process, by which these islands, according to Moreau de Jonnes, are in many instances formed, is sufficiently curious; first a submarine eruption raises from the bottom of the sea masses of volcanic products, which, as they do not rise above the surface of the water, but form a shoal a short way below its surface, serve as a foundation on which the Madreporites and other marine animals can commence their superstructure. Hence those beds of recent coralline limestone, seen covering the volcanic matter in many of the islands. The original reference in this case is to Alexander von Humboldt who had communicated directly with Moreau de Jonnès on the subject. See Humboldt, Personal Narrative, vol. 4, pp. 42-43; also M. Cortés and Alexandre Moreau de Jonnès, 'Mémoire sur la géologie des Antilles', Journal de physique, de chimie, d'histoire naturelle et des arts, vol. 70 (1810), pp. 130-131. Roussin, Le Pilote du Brésil, p. 47 states that on approaching the banks of Cape S. Roque: . . .nous croyons avoir observé que le sable est d'autant plus rare et les graviers d'autant plus communs, que les sondes sont plus petites et plus voisines des bancs.