Published online by Cambridge University Press: 14 March 2018
In the Mineralogical Magazine for September, 1930, Dr. Frederick Walker describes 'A tholeiitic phase of the quartz-dolerite magma of central Scotland'. Several pages of the article are devoted to a consideration of the phenomena he has observed in these rocks in their bearing upon certain views which I have expressed. In most respects Dr. Walker has clearly grasped the essential features of my thesis, and his efforts to obtain further information on the various points have been well directed. I am glad to welcome such a discussion as he has given, even though his conclusions are somewhat opposed to mine. In one respect, however, he has apparently overlooked an essential feature of my argument. On this matter, and on some points of evidence given, I should like to present some discussion. I desire also to examine certain other recent papers by Daly and Barth and by Bowen, Schairer, and Willems, in which the views expressed in my article have met with some criticism.
page 539 note 1 Fenner, C. N., The crystallization of basalts. Amer. Journ. Sci., 1929, ser. 5, vol. 18, pp. 225–253 CrossRefGoogle Scholar [Min. Abstr., vol. 4, p. 507].
page 542 note 1 Detailed descriptions will be published later, after the necessary laboratory work has been done.
page 544 note 1 Daly, R. A. and Barth, T. F. W., Geol. Mag. London, 1930, vol. 67, p. 109, footnote 2.Google Scholar
page 545 note 1 Daly, R. A. and Barth, T. Y. W., Geol. Mag. London, 1930, vol. 67, p. 481.CrossRefGoogle Scholar
page 545 note 2 N. L. Bowen, J. Y. Schairer, and H. W. V. Willems, The ternary system: Na2SiO3−Fe2O3−SiO2. Amer. Journ. Sci., 1930, ser. 5, vol. 20, pp. 405-455.
page 548 note 1 E. G. Zies, The fumarolic incrustations in the Valley of Ten Thousand Smokes. National Geogr. Soc. Washington, Contrib. Tech. Papers, 1924, Katmai ser., vol. 1, no. 3, p. 166 [Min. Abstr., vol. 2, p. 439].
page 548 note 2 L. V. Pirsson and C. Schuchert, A textbook of geology. 3rd edition, 1929, part 1, p. 267.
page 548 note 3 The secondary minerals occur chiefly in the interstices among the boulder-like masses of an extrusive pillow-lava. The conditions of occurrence show that the minerals are due to the action of thermal waters of ultimately meteoric derivation. The possibility that they represent in any sense residues from orthomagmatic crystallization is eliminated.
page 553 note 1 F. C. Phillips, Some mineralogical and chemical changes induced by progressive metamorphism in the Green Bed group of the Scottish Dalradian. Min. Mag., 1930, vol. 22, p. 247.
page 553 note 2 J. J. Sederholm, On synantetic minerals and related phenomena. Bull. Comm. Géol. Finlande, 1916, no. 48.
page 553 note 3 A. Knopf and C. A. Anderson, The Engels copper deposits, California. Econ. Geol., 1930, vol. 25, p. 33.
page 554 note 1 W. Lindgren, Mineral Deposits, 3rd edition, 1928, p. 204.
page 555 note 1 Holmes, A. and Harwood, H. F., The tholeiite dikes of the north of England. Min. Mag., 1929, vol. 22, pp. 1–52.CrossRefGoogle Scholar
page 557 note 1 Walker, F., The geology of the Shiant Isles. Quart. Journ. Geol. Soc. London, 1930, vol. 86, p. 374.CrossRefGoogle Scholar