The Philosophical magazine; a journal of theoretical, experimental and applied physics . der the influence of opposing pressures, must be subject to agreat amount of mutual friction or disturbance, by which theirfinal arrangeuient when wholly consolidated will be determined. Thus, suppose a mass of granite, of which A B (fig. 4) repre-sents the section, consisting of crystals of felspar and mica irre-gularly disposed in a basis of more or less liquefied or gelatinoussilex, exposed to movement in the direction A B, while undervast pressure both from above and below, that is, in the oppo-site di
The Philosophical magazine; a journal of theoretical, experimental and applied physics . der the influence of opposing pressures, must be subject to agreat amount of mutual friction or disturbance, by which theirfinal arrangeuient when wholly consolidated will be determined. Thus, suppose a mass of granite, of which A B (fig. 4) repre-sents the section, consisting of crystals of felspar and mica irre-gularly disposed in a basis of more or less liquefied or gelatinoussilex, exposed to movement in the direction A B, while undervast pressure both from above and below, that is, in the oppo-site directions C and I). Whether the surface C or D, or both,remained fixed, or merely moved, owing to resistances, at aslower rate than the other parts, the crystals in the latter wouldbe turned round by internal friction, and rearranged and drawnout in stripes or planes in the direction of the motion, while the and the Nature of the Liquidity of Lavas. 197 proportionate dimensions of the mass would be equally varied soas to produce a section something like E^ F, G, H (tig. 5); in Fig. fact, a rock which, if no further change occurred in it exceptconsolidation in place, would have all the characteristics ofgneiss. The same movement, if still further continued, might,it appeared to me, be expected to disintegrate the angular cry-stals of felspar altogether, so as to cause them to disappear,perhaps to force their elementary molecules to melt into the in-tensely heated silicate, to which they would impart their the resulting rock, supposing the laminae of the mica-crystals to slide readily past each other, when lubricated by thesilicate, and not therefore to be so far disintegrated as those offelspar (as from their peculiar form might be expected), would puton a lamellar structure, and very much resemble mica-schist,—especially since the great flexibility of the mica would render itslaminae extremely liable to yield to the irregularities of pressurepervading the mass
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