^{page 166 note 1} The term “composite intrusion” is here used in the sense given to it by Bailey, and Thomas, in “The Tertiary and Post-Tertiary Geology of Mull, etc.” Mem. Geol. Surv., 1924, 32. See also p. 178 of this paper.Google Scholar

^{page 166 note 2} For a general and historical account with references to the older literature, see Harker, A., “The Tertiary Igneous Rocks of Skye” Mem. Geol. Surv., 1904. 197–201.Google Scholar

^{page 166 note 3} Richey, J. E., Trans. Geol. Soc. Glasgow, xvii, 1927–1928, 247–58.Google Scholar Richey, J. E. and others in “The Geology of North Ayrshire” Mem. Geol. Surv., 1930, 69.Google Scholar

^{page 166 note 4} Tyrrell, G. W., Trans. Geol. Soc. Glasgow, xiv, 1912, 219–57.Google Scholar

^{page 166 note 5} Bailey, E. B. and others in “The Geology of the Glasgow District” Mem. Geol. Surv., 1925, 137–40.Google Scholar

^{page 167 note 1} In the Markle type of basalt, macro-phenocrysts of labradorite-bytownite up to 1·5 cms. long are set in a groundmass of acid labradorite, augite, subordinate olivine, and magnetite. For definitions and a general discussion of the Carboniferous olivine-basalts and mugearites, see MacGregor, A. G., Trans. Geol. Soc. Glasgow, xviii, 1928, 324–60.Google Scholar

^{page 172 note 1} Harker, A., “Geology of the Small Isles, etc.”: Mem. Geol. Surv., 1908, 131.Google Scholar

^{page 172 note 2} Washington, H. S., “Petrology of the Hawaiian Islands”: I. Kohala and Mauna Kea: Am. Jour. Sci., v, 1923.Google Scholar

^{page 172 note 3} This rock being a transitional type does not fit readily into the classification. It is, strictly speaking, a basaltic mugearite with the addition of large phenocysts of basic plagioclase but has been named basalt, as it seemed inadvisable to extend the term “mugearite” to include a rock so rich in phenocrysts of basic plagioclase. It might, however, be termed labradoritephyric basaltic mugearite.

^{page 173 note 1} Buch, Leopold von, Physicalische Beschreibung der Canarischen Inseln, Berlin, 1825, 229.Google Scholar

^{page 173 note 2} Darwin, Charles, Geological Observations, 2nd ed., 1875, 132.Google Scholar

^{page 174 note 1} Op. cit., 132–3.Google Scholar

^{page 174 note 2} Bailey, E. B. and Thomas, H. H., “The Tertiary and Post-Tertiary Geology of Mull, etc.” Mem. Geol. Surv., 1924, 33.Google Scholar

^{page 174 note 3} Harker, A., “The Tertiary Igneous Rocks of Skye” Mem. Geol. Surv., 1904, 298.Google Scholar

^{page 175 note 1} Unfortunately there exists at present on suitable term for a magma containing suspended crystals which under conditions of rapid cooling would give rise to a coarsely porphyritic rock. The term “porphyritic magma” is here used to designate such a type.

^{page 175 note 2} Tyrrell, G. W., “Geology of the Cumbrae Islands”: Trans. Geol. Soc. Glasgow, xvi, 253.Google Scholar

^{page 176 note 1} Tyrrell, G. W., Trans. Geol. Soc. Glasgow, xiv, 1912, 226.Google Scholar

^{page 176 note 2} Harker, A., “The Tertiary Igneous Rocks of Skye”: Mem. Geol. Surv., 1904, 256–70.Google Scholar

^{page 176 note 3} This was found to be the case at Druim na Criche as well as at Roineval, and the phenomenon is not confined to the latter locality, as stated by Harker. See Harker, A., op. cit., 256.Google Scholar

^{page 177 note 1} Harker, A., “The Tertiary Igneous Rocks of Skye”: Mem. Geol. Surv., 1904, 259 and 263.Google Scholar

^{page 178 note 1} Harker, A., “The Tertiary Igneous Rocks of Skye”: Mem. Geol. Surv., 1904, 269.Google Scholar Harker, A., “The Geology of the Small Isles, etc.”: Mem. Geol. Surv., 1908, 129.Google Scholar

^{page 178 note 2} Bailey, E. B., “The Sgù'r of Eigg”: Geol. Mag., 1914, 303.Google Scholar Bailey, E. B. and others, “The Tertiary and Post-Tertiary Geology of Mull, etc.”: Mem. Geol. Surv., 1924, 95–6.Google Scholar

^{page 179 note 1} There are three conditions attached to the new definition: (1) Composite intrusions are composed of parts of recognizably different composition; (2) As a complex they chill exteriorly against country-rock; (3) The component parts do not chill against one another—if they do the intrusion is multiple, not composite. See Bailey, E. B. and Thomas, H. H.. in “The Tertiary and Post-Tertiary Geology of Mull, etc.”: Mem. Geol. Surv., 1924, 32.Google Scholar

^{page 179 note 2} This asymmetry resulting from composite extrusion must not be confused with that produced in an intrusive sheet by gravitative differentiation in situ such as in the peculiar differentiated sill described by Iddings from Electric Peak, Montana. See Iddings, J. P. and others in “The Geology of the Yellowstone National Park”: Monograph 32, U.S.G.S., 2, 1899, 82–4.Google Scholar

^{page 180 note 1} Washington, H. S., Aurousscau, M., and Mary, G. Keyes, “The Lavas of Etna”: Am. Jour. Sci., xii, 1926, 371–408.CrossRefGoogle Scholar

^{page 180 note 2} Op. cit., 398.Google Scholar

^{page 180 note 3} Op. cit., 401.Google Scholar