XXXI. The Origin of Granite

Abstract

The author in the first instance contested the generally-accepted theory that granite is of plutonic origin, or, in other words, part of the molten or plastic magma which occupies the interior of the Earth. After referring to the evidences offered in support of this theory, such as the alteration on neighbouring rocks and the arms of granite which penetrate surrounding strata, he pointed out that the great mass of granite in Arran must have reached at one time such an altitude, that had it either been molten or plastic it would have spread itself over the whole island, and filled up Kilbrannau Sound. Its elevation can still be approximately estimated from the rising tangents of the sides of the existing mass. The angle of dip is well seen at several points where it rises not far from the perpendicular, and, prolonging that rise afterwards at a gradually lessening angle, a cone nearly as high as the whole length of Arran would be the result. Without assuming that a perfect cone was ever formed, it is certain that the granite formed an immense mountain before denudation began to wear it down, and that it would not have held together if it had been plastic in the slightest degree. To arrive at a reasonable view of the origin of granite, it is necessary to begin at a very early stage of the Earth's history. Sir Robert Ball in his latest work, “The Earth's Beginning,” attributes the origin of our planet to a This 250-word extract was created in the absence of an abstract