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XVIII.—The Trachytic and Allied Rocks of the Clyde Carboniferous Lava-Plateaus

Published online by Cambridge University Press:  15 September 2014

G. W. Tyrrell
G. W. Tyrrell
Affiliation:
University of Glasgow
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Extract

The lavas of the Scottish Carboniferous are predominantly basaltic. True andesites and rhyolites are conspicuous by their absence, whilst trachytes and allied rocks are present in quite subordinate quantity. This association of basalt and trachyte is in accordance with the fact that the basalts have a slight alkaline cast, which is evidenced by an alkali content greater than that of the average basalt, and by the occasional presence of nepheline and analcite amongst their constituents. The transition from basalts to more acid types is accomplished, not by way of the andesites, but through the mugearites, volcanic rocks with chemical affinities to the essexites. All transitions from the more felspathic types of basalts, the Jedburgh and Markle types, can be traced through mugearites to trachytes or allied rocks.

Type
Proceedings
Information
Proceedings of the Royal Society of Edinburgh , Volume 36 , Issue 3-4 , 1917 , pp. 288 - 299
Copyright
Copyright © Royal Society of Edinburgh 1917

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References

page 288 note * Hatch, F. H., Trans. Roy. Soc. Edinburgh, vol. xxxvii, 1892, pp. 115–126Google Scholar.

page 288 note † Geol. Surv. Mem.: Geology of East Lothian, 1910, pp. 127–133.

page 288 note ‡ Barron, T., Geol. Mag. (iv), iii, 1896, pp. 371–378CrossRefGoogle Scholar.

page 288 note § Lady MacRobert, , Quart. Jour. Geol. Soc., vol. lxx, 1914, pp. 303–315.CrossRefGoogle Scholar

page 292 note * Mem. Geol. Surv.: North Arran, South Bute, and the Cumbraes, 1903, p. 177.

page 292 note † Mem. Geol. Surv.: Geol. of Glasgow District, 1911, p. 110.

page 292 note ‡ Mem. Geol. Surv.: Geol. of Glasgow District, 1911, p. 104, 109.

page 292 note § Summ. Prog. Geol. Surv. for 1913 (1914), p. 58. Since the above was written, Mr G. V. Wilson, of the Scottish Geological Survey, has read a paper to the Glasgow Geological Society (March 9, 1916) on the vents of North Ayrshire, in which some of these trachytic rocks are described in detail. See “Preliminary Notes on Volcanic Necks in N.W. Ayrshire,” Trans. Geol. Soc. Glasgow, vol. xvi, pt. I (1915–16), 1916, pp. 86–99.

page 293 note * Mem. Geol. Surv.: North Arran, South Bute, and the Cumbraes, 1903, p. 62.

page 293 note † Mem. Geol. Surv.: Geol. of Glasgow District, 1911, p. 145.

page 293 note ‡ Mem. Geol. Surv.: Geol. of East Lothian, 1910, p. 132.

page 293 note § Lady MacRobert, , Q.J.G.S., vol. lxx, 1914, p. 305.Google Scholar

page 295 note * Op. cit., p. 309.