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58 A DESCRIPTION OF THE [Ch. V. CHAPTER V. DESCRIPTION OF THE SCHISTOSE ROCKS ASSOCIATED WITH GRANITE IN VARIOUS COUNTRIES. Mica-slate and clay-slate of the eastern part of Ireland. — Their alternations with quartz-rock and hornblende-rock, — their associations with granite. — The composition of this granite, and its modes of arrangement. — The gneiss formation of the Western Isles of Scotland. — Its beds of mica-slate, green stone, compact felspar, clay-slate, talc-schist, serpentine, limestone, and quartz- rock. — The nature of their connection with each other and with the gneiss.— Abounds in bunches and veins of granite. — Description of the primary schistose rocks of Norway, — gneiss, mica-slate, clay-slate, — with their sub ordinate beds. — They contain immense beds of granite, and are inter- stratified with smaller ones. — The primary schistose group of Saxony, — gneiss, mica-slate, clay-slate, and shorl-schist. — The talcose formations. — Of the Alps, — including talcose granite or protogine, talc-schist, serpentine, and other magnesian rocks. — Of the island of Corsica, composed of granite, curite, protogine, hornblende-rock, cuphotide, talc-schist, serpentine, and analogous rocks. In attempting to show that the primary or crystalline schists of different countries are the equivalents of those of Cornwall, it is not intended to assert that they are all of the same nature, and referrible to precisely the same geological epoch: on the contrary, it is wished, for the present, to avoid all conjectures concerning the nature of their origin, and only to express that these slates do, as in Cornwall, bear a certain relation to the granite with which they are associated; and consequently all slates, both foreign and Cornish, which have the same relative connection and position with the granite, may be regarded as parallel or equivalent rocks. These equivalent schists are commonly of a very different nature, which might have been expected a priori; for even in Cornwall the suites of slates vary when connected with different masses of granite; still, however, although their composition is not identical, they undergo analogous mutations, resulting from the proportions of the constituent parts, and the manner