Note 411 — Chapter XLVII · THE ACID BOSSES OF MULL, SMALL ISLES, ST. KILDA, ARRAN AND THE NORTH-EAST OF IRELAND

In his paper, Proceed. Inverness Field Club, vol. iii. (1884), p. 78, Mr. Ross quotes a letter from Prof. Judd, who there states that the rock supposed to be granite "is seen under the microscope to be a quite different rock—a quartz-diorite." Some of the specimens from St. Kilda collected by Mr. Ross were exhibited at a meeting of the Geological Society on 25th January 1893. With regard to these Prof. Judd, in the course of the discussion on his paper on "Inclusions of Tertiary Granite in the Gabbro of the Cuillin Hills," remarked:—"They show a dark rock traversed by veins of a light one, but the dark rock is not a gabbro and the light one is not a granite" (Quart. Journ. Geol. Soc. vol. xlix. (1893), p. 198).