304. An argument, directed at once against the igneous origin and unstratified nature of all granite, is given in a work already mentioned. "If granite had flowed from below, how does it happen, that, after it had burst through the strata of micaceous schistus, &c. it did not overflow the neighbouring country? If this hypothesis were true, Mont Blanc could never have existed."[156] [Footnote 156: Mineralogy of the Scottish Isles, vol. ii. p. 166.] A theory is never more unfairly dealt with, than when those parts are separated which were meant to support one another, and each left to stand or fall by itself. This, however, is precisely what is done in the present instance; for Dr Hutton's theory of granite would not deserve a moment's consideration, if it were so inartificially constructed, as to suppose that granite was originally fluid, and yet to point out no means of hindering this fluid from diffusing itself over the strata, and settling in a horizontal plane. The truth is, that his theory, at the same time that it conceives this stone to have been in fusion, supposes it to have been, in that state, injected among the strata already consolidated; to have heaved them up, and to have been formed in the concavity so produced, as in a mould. Thus Mont Blanc, supposing that it is unstratified, is understood to consist of a mass that was melted by subterraneous heat under the strata, and being impelled upwards by a force, that may stand in some comparison with that which projected the planets in their orbits, heaved up the strata by which it was covered, and in which it remained included on all sides. 305. The covering of strata, thus raised up, may have been burst asunder at the summit, where the curvature and elevation were the greatest; but the melted mass underneath may have already acquired solidity, or may have been sustained by the beds of schistus incumbent on its sides. This schistus, forming the exterior crust, was immediately acted on by the causes of waste and decomposition, which have long since stripped the granite of a great part of its covering, and are now exercising their power on the central mass. That even Mont Blanc itself, as well as other unstratified mountains, was once covered with schistus, will appear to have in it nothing incongruous, when we consider the height to which the schistus still rises on its sides, or in the adjacent mountains; and when we reflect, that, from the appearances of waste and degradation which these mountains exhibit, it is certain, that the schistus must have reached much higher than it does at present.