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IV.—On the So-called Spilites of Jersey

Published online by Cambridge University Press:  01 May 2009

T. G. Bonney  and
Catherine A. Raisin
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Extract

About one quarter of the Island of Jersey is occupied by argillites or fine grits, often of a greenish grey colour referred by French geologists to the “Phyllades de St. Lo.” They are, therefore, if not equivalent to the Lower Cambrian beds of Britain, slightly more ancient.inclose association with these, but according to Prof, de Lapparent, belonging rather to the upper part of the group, occur certain more or less porphyritic rocks, as to the origin of which different opinions have been entertained. M. Nouryinhis useful “Geologie de Jersey ” describes them under the name of “spilites.” While admitting that in many respects they exhibit the characters of an eruptive rock, he concludes, after an elaborate discussion, that they are metamorphosed argillite, the change being primarily due to the “poiphyres pétrosiliceux;” the felspar crystals, however, he thinks, may be attributed to the action of the diorite.

Type
Original Articles
Information
Geological Magazine , Volume 10 , Issue 2 , February 1893 , pp. 59 - 64
Copyright
Copyright © Cambridge University Press 1893

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References

Page 59 note 1 Bull. Soc. Géol. de France, vol. xvi. p. 412, A. Bigot; and Bull, du Lab. de Géol. de la Faculté des Sciences de Caen., A. Bigot, 12, 1890, p. 11.Google Scholar

Page 59 note 2 de Jersey, Geologie, 1886, M. Noury, pp. 59, 61, 63.Google Scholar

Page 59 note 3 Bull. Soc. Géol de France, 1884, tome xii. p. 288Google Scholar; Q.J.G.S., 1891, vol. xlvii. p. 36Google Scholar; Comptes fiendus, 1890, vol. III, p. 543. After the completion of the manuscript of this paper, We received a copy from Prof. de Lapparent of his newly Published “ Note sur les Roches Eruptives de I'Ile de Jersey’ (ann. de la Soc. scientif. de Bruxelles, tome xvi. 2e partie)inwhich these “spilites” are described. But as he refers chiefly to other quarries and eDters on the whole into fewer details than we have done, the results of our work may be still of some little interest, at any rate to English readers.Google Scholar

Page 59 note 4 Q.J.G.S. 1884 vol. xl. p. 404Google Scholar; Q.J.G.S. 1887 vol. xliii. p. 322Google Scholar; Q.J.G.S. 1889 vol. xlv. p. 380Google Scholar; Q.J.G.S. 1892 vol. xlviii. p. 122.Google Scholar

Page 60 note 1 or “Gallows Hill,” as it is named on some maps.

Page 63 note 1 In it at the time of our visit,in1888, stood the building of an athletic club. —T.G.B.

Page 63 note 2 It is cut by two or three “greenstone” dykes.

Page 63 note 3 It is impossible to obtain any definite results.

Page 63 note 4 Many of the rocks here are greenish to purplish argillites, sometimes rather flinty, which recall certain parts of the Longmynd group.

page 64 note 1 de Jersey, Géologie, pp. 53, 126.Google Scholar