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VI.—The Chawfordjohn Essexite and Associated Rocks

Published online by Cambridge University Press:  01 May 2009

Alexander Scott
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Extract

Although the so-called Crawfordjohn essexite has been mentioned several times in petrographic literature, no detailed description of the occurrence has been given. In 1888 Teall described the main rock of the intrusion as an abnormal variety ofthe N. W.-S.E. Kainozoic dykes and noted the porphyritic augite andthe abundance of felspar, olivine, and apatite. Lacroix, in a generalpaper on the teschenites, mentioned the occurrence of nephelite in the same rock, which he described as an “olivine-teschenite, passing instructure to a tephrite”. Bailey, in the Glasgow memoir, remarked on the close similarity between the Crawfordjohn and Lennoxtown rocks and classed them with the essexites on account of their chemical similarity to the Brandberget rocks, while Tyrrell, on account ofthis similarity and also of the resemblance to the Carclout essexite, included them in the late Palaeozoic alkaline group.

Type
Original Articles
Information
Geological Magazine , Volume 2 , Issue 10 , October 1915 , pp. 455 - 461
Copyright
Copyright © Cambridge University Press 1915

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References

page 455 note 1 No mention of it is made in the Explanation of Surv. Scotland), 1871.Google Scholar

page 455 note 2 British Petrography, 1888, p. 197.Google Scholar

page 455 note 3 Compt. Rend., cxxx, p. 1273, 1900.Google Scholar

page 455 note 4 Geology of Glasgow District(Mem. Geol. Surv.), 1911, pp. 113, 130.Google Scholar

page 455 note 5 Brögger, W. C.,Quart. Journ. Geol. Soc., 1, pp. 15–38, 1894.CrossRefGoogle Scholar

page 455 note 6 Geol. Mag. [5], IX, p. 121, 1912.Google Scholar

page 455 note 7 The Craighead Hill, mentioned in The Silurian Rocks of Britain(Mem. Geol. Surv.), i, 1899, pp. 462–3, 501, lies in the Girvan Valley, Ayrshire.Google Scholar

page 456 note 1 British Petrography, 1888, p. 197.Google Scholar

page 456 note 2 Bemrose, H. H., Quart. Journ. Geol. Soc., 1, pp. 603–34, 1894.CrossRefGoogle Scholar

page 457 note 1 H. W. Monckton, ibid., I, pp. 40–1, 1894; H. H. Bemrose, loc. cit.;Flett, J. S. in Geology of East Fife(Mem. Geol. Surv.), 1902, p. 392Google Scholar; Young, R. B.,Trans. Edin. Geol. Soc., viii, p. 327, 1903Google Scholar; Reynolds, S. H., Quart. Journ. Geol. Soc., lxiv, p. 508, 1908.Google Scholar

page 457 note 2 Scott, A., Min. Mag., xvii, pp. 100–10, 1914.Google Scholar

page 458 note 1 Cf. Campbell, R. & Stenhouse, A. G., Trans. Edin. Geol. Soc., ix, p. 126, 1907.Google Scholar

page 458 note 2 Includes some turbid unidentified matter.

page 458 note 3 Includes a little hornblende.

page 458 note 4 Cf. Tyrrell, G. W., Geol. Mag. [5], IX, p. 121, 1912. The writer is indebted to Mr. Tyrrell for the loan of slides of this rock.Google Scholar

page 458 note 5 Ibid., p. 77.

page 458 note 6 Ibid., p. 123.

page 459 note 1 Cf.Flett, J. S.in Geology of Edinburgh(Mem. Geol. Surv.), 1910, p. 295.Google Scholar

page 459 note 2 Summary of Progress of Geological Survey for 1907, 1908, p. 55; E. B. Bailey, loc. cit., p. 130.

page 459 note 3 Brögger, W. C., loc. cit., p.19.Google Scholar

page 459 note 4 Adams, F. D.,Geological Congress, Canada, 1913, Guide-book No. 3, p.39.Google Scholar

page 459 note 5 Bailey, E. B., loc. cit., p. 134.Google Scholar

page 459 note 6 Another analysis of more impure material is given byTyrrell, G. W., Geol. Mag. [6], II, p. 363, 1915.Google Scholar

page 459 note 7 Loc. cit.

page 460 note 1 Bull, . Essex Inst., xxiii, p. 146,1891.Google Scholar

page 460 note 2 Mikroskopische Physiographie, 4th ed., 1908, ii, i, p. 404.Google Scholar

page 460 note 3 Loc. cit.

page 460 note 4 Adams, F. D., loc. cit.; also Journ. Geol., xi, pp.239–98, 1903CrossRefGoogle Scholar; Dresser, J. A., Geol. Surv. Canada, Mem. No. 7, pp.14–18, 1910Google Scholar; J. J. O'Neill, ibid., Mem. No.43, pp.28–84, 1914, etc.