615. It may be said that gneiss and mica-schist originated only because there were fathomless valleys in the granite, in which the dissevering actions were inclosed, and extended themselves from one mountain-wall to another, while the light could be reflected in them and heat the earth.
616. So long as the granite was devoid of valleys, so long also did no other formation originate. This is proved by the fact that upon the highest mountains the granite is bare and uncovered, while this is not the case upon its lateral walls. It is therefore the second and third earth-rain that first originated, after the earth was heated. Gneiss and mica-schist are, so to speak, precipitated by reflected light.
617. The principal valleys of gneiss and mica-schist have not originated by themselves, but have been modelled according to the form of the granitic valleys. The valleys of those earth-precipitates are properly only subsequent valleys.
618. The lamination is not everywhere a mechanical phenomenon, but without doubt also a polar. It is exactly the same law, which determines the lamination of crystals, that does that of the strata of the earth, and operates also in producing their lamination.
PRIMARY LIMESTONE.
619. The earths must be viewed as one mass, the component parts of which observe a mutual relation. Now, after the silex, clay and talc had been precipitated, a proportionate abundance of lime became free, which was then thrown down at the end of this period of precipitation, as Primary limestone.
620. The calcareous mass may be viewed as corrosive earth, from which a certain quantity of carbon has been set free. As such, and combined with the oxygen developed out of the water by the influence of light to form carbonic acid, the lime was insoluble and was precipitated.
621. The primary limestone has also not been mechanically deposited. It has a crystalline texture, is a calcareous granite, and generally succeeds the mica-schist formation.
b. Water-Formation—Transition-Rocks.
METAMORPHOSIS OF THE PRIMARY PRECIPITATIONS.