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IV.—The Penmaenmawr Intrusions

Published online by Cambridge University Press:  01 May 2009

H.C. Sargent
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Extract

The subject of this paper is a group of three intrusive masses of igneous rock, possibly laccolitic in their origin, whose outcrops are situated within a radius of a mile from the village of Llanfairfechan, on the north coast of Carnarvonshire.

Type
Original Articles
Information
Geological Magazine , Volume 2 , Issue 1 , January 1915 , pp. 15 - 27
Copyright
Copyright © Cambridge University Press 1915

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References

page 15 note 1 Brydone, , The Stratigraphy of the Chalk of Hants, p. 88; London, Dulan & Co., Ltd., 1912.Google Scholar

page 15 note 2 Op. cit., p. 86 and (under erroneous number 859) p. 92.

page 15 note 3 “On the Chemical and Mineralogical Changes which have taken place in certain Eruptive Rocks of North Wales”: Q.J.G.S., vol. xxxiii, pp. 423–9, 1877.Google Scholar

page 15 note 4 British Petrography, 1888, p. 273.Google Scholar

page 15 note 5 The Bala Volcanic Series of Caernarvonshire, 1889, p. 64.Google Scholar

page 15 note 6 The Petrology of the Igneous Rocks, 7th ed., 1914, p. 369.Google Scholar

page 16 note 1 Mikr. Phys. d. mass. Gest., 2nd ed., 1887, p. 204.Google Scholar

page 16 note 2 Lehrbuch der Petrographie, 2nd ed., vol. ii, p. 641, 1894.Google Scholar

page 16 note 3 “Ueber den Quarznorit von Penmaenmawr in Wales und seine Schlieren-bildungen”: Neues Jahrbuch für Mineralogie, etc., Abh., pp. 93–121, 1905.Google Scholar

page 16 note 4 Op. cit., p. 62.

page 16 note 5 A misprint on the Geological Survey Map for Ty'n-rhedyn.

page 18 note 1 The Bala Volcanic Series of Caernarvonshire, 1889, p. 113.Google Scholar

page 18 note 2 The Geology of North Wales (Mem. Geol. Surv. England and Wales), vol. iii, 2nd ed., p. 326, 1881Google Scholar. See also Harker, , “Notes on the Geology of Mynydd Mawr”: Geol. Mag., Dec. III, Vol. V, pp. 221–6, 1888.CrossRefGoogle Scholar

page 18 note 3 Op. cit., p. 94.

page 19 note1 Twenty-seven thin sections of Penmaenmawr, two of Carregfawr, and five of Dinas have been examined.

page 19 note 2 Op. cit., p. 96.

page 20 note 1 “Ueber den Quarznorit von Penmaenmawr in Wales und seine Schlieren-bildungen”: Neues Jahrbuch für Mineralogie, etc., Abh., p. 100, 1905.Google Scholar

page 20 note 2 Midland Naturalist, 1885, p. 5.Google Scholar

page 21 note 1 “Ueber den Quarznorit von Penmaenmawr in Wales und seine Schlieren-bildungen”: Neues Jahrbuch für Mineralogie, etc., Abh., pp. 111 et seq., 1905.Google Scholar

page 21 note 2 Op. cit., p. 115.

page 21 note 3 Op. cit., p. 275.

page 22 note 1 “Die von Schaub mitgeteilten Analysen dieser Schlieren lassen sich kaum als Differentiationsprodukte verstehen, sondern deuten eher auf Zersetzungserscheinungen”: Mikr. Phys., 4th ed., vol. ii, p. 1258, 1908Google Scholar. [The analyses of the veins, communicated by Schaub, can scarcely be considered differentiation products, but rather suggest that they are the effects of decomposition.—Ed.]

page 25 note 1 Text-book of Petrology, 5th ed., p. 219, 1909.Google Scholar

page 25 note 2 Since the above was written the writer finds that Rosenbusch was latterly inclined to take the same view. “Doch kann man es wegen seiner ausgesprochen porphyrischen Struktur nicht wohl zu den Noriten stellen. Ob man es nicht besser seiner chemischen Konstitution nach, zumal wegen seines hohen Gehaltes au Kieselsäure zu den Enstatit-porphyriten stellen sollte, darüber liesse sich streiten” (Mikr. Phys., 4th ed., vol. ii, p. 1258, 1908)Google Scholar. [One cannot, in consequence of its pronounced perphyritic structure, very well class it with norites. It is an open question if it would not be better, having regard to its chemical composition, and particularly considering the amount of silica it contains, to class it with the enstatite-porphyrites.—Ed.]

page 26 note 1 The Bala Volcanic Series of Caernarvonshire, 1889, p. 120.Google Scholar

page 26 note 2 The writer hopes to describe this series of lavas in detail in a future paper.

page 26 note 3 Harker, op. cit., p. 124.