1. OF THE FORMATIVE PROCESS. How long the earth existed before being brought into a habitable condition for either vegetable or animal bodies, geology has no means of determining. The primary crystalline beds are the oldest rocks of which we have any knowledge: we can penetrate at least to no antecedent matter, bearing the record of its own age, out of which these rocks were produced. We are warranted, therefore, in accounting for their origin, to remount at once to the initial creative act which called them into being, and the presumption is, that no great length of time was occupied in this arrangement. The Divine will commanded, every particle obeyed, and all took their places. The eruptive rocks are of comparatively sudden growth: they are not the result of a gradual deposition, but of igneous fusion in the interior of the earth, and elevated to the surface through the operation of forces of rapid activity. How long our planet was in thus assuming form, and the dry land appearing, we have no certain means of judging, except by looking to the end of its creation, and assuming that the “void” was not permitted indefinitely to continue. The occupancy of life at once exalts the work and illustrates its purpose. The fossiliferous strata were formed in different circumstances and under different conditions, when the course of nature, if we may so speak, was fully established, and the train of events under the operation of physical law commenced its onward march. The oldest of the fossiliferous deposits is the Silurian. It likewise constitutes one of the greatest depth, as well as of extent, on the surface of the globe. The position, generally, of the silurian beds, is along the line of the great mountain-chains, except in Russia, where they spread over the interior, and thin out into smaller dimensions, and where, from the absence of the intrusive rocks, they are only semi-indurated. This system of rocks was, therefore, formed in circumstances the most favorable for rapid accumulation, amidst such primal operations of nature as have never been repeated upon the same scale of magnitude. The first shaping-out, if we may so speak, of the earth’s surface, in the elevation of its mountain-ranges and corresponding depressions of the sea-bottom, bears all the marks of a single cotemporaneous act, not completed in a moment of time indeed, but continued through a period of unparalleled spasmodic agency. Every region shared in the convulsive movements, and the whole earth, in one and the same age, was begirt with mountains. These violent throes were accompanied everywhere with violent action upon the already consolidated masses. Disintegration would keep pace upon them with the rate of uprise. And as the bare jagged rocks unprotected with herbage, friable and just rending from the fire, were lifted suddenly above the waters, the waters in turn would dash violently upon their sides and broken serrated crests, and so become as rapidly filled again with all