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III.—On the Origin of the Stone-Rivers of the Falkland Islands

Published online by Cambridge University Press:  01 May 2009

Charles Davison
Charles Davison
Affiliation:
Mathematical Master at King Edward's High School, Birmingham.
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Extract

The stone-rivers of the Falkland Islands have been described by Mr. Darwin, Sir Wyville Thomson, Dr. Coppinger, and other naturalists who have visited those regions. The accounts given by the two first-named are well-known and easily accessible, and render a full description here unnecessary. But it may not be out of place to summarise the principal features of the stone-rivers, which must find an explanation in any satisfactory theory of their origin.

They consist of angular blocks of quartzite, “arranged,” according to Pernéty, “as if they had been accumulated carelessly to fill the ravines.” The blocks are from two to twenty feet long, and rest “irregularly one upon the other, supported in all positions by the angles and edges of those beneath” (Thomson).

Type
Original Articles
Information
Geological Magazine , Volume 6 , Issue 9 , September 1889 , pp. 390 - 393
Copyright
Copyright © Cambridge University Press 1889

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References

page 390 note 1 Pernéty, A. J., Histoire d'un Voyage aux Isles Malouires, etc. (nouv. éd., 1770, Paris), vol. ii. pp. 1–6;Google Scholar Darwin, C., Journal of Researches, etc. (1879), pp. 196–199;Google Scholar SirThomson, C. Wyv., The Movement of the Soilcap; Nature (02. 22, 1877), vol. xv. pp. 359–360;Google Scholar also, Voyage of the ‘Challenger,’ vol. ii. pp. 245–249;Google Scholar and the Enc. Brit., art. on the Falkland Islands; DrCoppinger, R. W., Cruise of the “Alert” (1885), pp. 32 33.Google Scholar

page 391 note 1 The Movement of the Soilcap: Nature (03 8, 1877), vol. xv. pp. 397–398.Google Scholar

page 391 note 2 Himalayan Journals (1854), vol. ii. p. 179 (footnote).Google Scholar

page 391 note 3 Agassiz, Louis: His Life and Correspondence, edited by Agassiz, E. C., vol. ii. pp. 694–695.Google Scholar Extract from a letter to Prof. B. Peirce, dated Feb 20, 1871. It should be noted that Agassiz's intention of visiting the Falkland Islands was never carried out.

page 391 note 4 Note on the Movement of Scree-material: Quart. Journ. Geol. Soc. (1888) vol. xliv. pp. 232–237.Google Scholar

page 392 note 1 “ The temperature is very equable, the average of the two midsummer months being about 47° Fahr., and that of the two winter months 37° Fahr. The sky is almost constantly overcast, and rain falls, mostly in a drizzle and in frequent showers, on about 250 days in the year. The rainfall is not great, only about 20 inches.” Enc. Brit., art on the Falkland Islands.

page 392 note 2 It should be noted that the quartzite bands are often much crumpled and distorted, but the surface of the stone-rivers would be fairly smooth in any part, if the total thickness of the quartzite bands formerly above that part were approximately the same all over it. Sir Wyville Thomson states, however, that “the general colouring [of the islands] is dark brownish-green, relieved along the strike of the hills by veins of white quartzite denuded by the wearing away of softer rocks on both sides, and left projecting on the mountain-slopes like dilapidated stone dykes” (Enc. Brit.).

page 393 note 1 “Why,” asks Dr. Coppinger, “do they [the stone-rivers] exhibit a margin so sharp and well-defined, yet without the elevated rounded appearance of a riverbank?”