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2. On the Microscopic Characters of Volcanic Ashes and Cosmic Dust, and their Distribution in the Deep Sea Deposits

Published online by Cambridge University Press:  15 September 2014

John Murray ,
Mons. A. Renard  and
John Murray
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Extract

In the Session of 1876, Mr John Murray communicated to this Society a paper on the distribution of volcanic debris over the floor of the ocean, and in it announced the discovery of cosmic dust in deep sea deposits. It was shown that at points, where neither the action of waves, rivers, or currents can transport the debris of continents, volcanic materials play the most important role in the formation of the mineral constituents of the deep sea deposits. It was pointed out that pumice, on account of its structure, was able-to float to great distances, but in time became waterlogged and sank to the bottom, there to decompose. On the other hand, incoherent volcanic matters, ejected in the form of lapilli, sand, and ashes, into the higher regions of the atmosphere, may, ceteris paribus, be conveyed, in consequence of their small dimensions and structure, to greater distances than other mineral particles derived from the continents. The possibility was also admitted that submarine volcanic eruptions might also contribute to the accumulation of those silicates and pyrogenous minerals and rocks, whose microscopic characters and distribution at the bottom of the sea we shall presently point out.

Type
Proceedings 1882-83
Information
Proceedings of the Royal Society of Edinburgh , Volume 12 , 1884 , pp. 474 - 495
Copyright
Copyright © Royal Society of Edinburgh 1884

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References

note * page 474 Proc. Moy. Soc. Edin., 1876–1877.Google Scholar

note * page 475 “Les cendres volcaniques de l'éruption du Krakatau” (Bull. Acad. Roy. de Belgique, sér. 3, t. vi. No. 11 Séance du 3 Nov. 1883).Google Scholar

note * page 477 Comptes rendus de l'Académie des Sciences, 19 Nov. 1883, p. 1101.Google Scholar

note * page 480 Just as we can divide pumice microscopically according as it is acid or basic, so the products of its trituration may be recognised under the microscope, inasmuch as the former often give colourless and more elongated particles, while the fragments of basic pumice have a more pronounced tint and more rounded pores.

note * page 481 Lately the works on these same ashes have made known as accidental elements pyrites, apatite, and perhaps biotite (?). It is to be remarked, however, that these minerals must be extremely rare in comparison with the vitreous matters and mineral species above-mentioned.

note * page 482 Penck, , “Studien über lockere vulkanische Auswürflinge,” Zeitschr. d. deutsch. geol. Gesellsch., 1878.Google Scholar

note † page 482 Schuster, , “Bemerkungen zu E. Mallard's Abhandlung sur l'isomorphisme des feldspaths tricliniques, &c,” Min. petr. Mitth., v. 1882, p. 194.Google Scholar

note † page 484 A recent determination of titanic acid has given 0.62 per cent. TiO2

note * page 489 Proc. Eoy. Soc. Edin.