Hundreds of thousands of years ago, the earth, now so busy and full of life, rolled on its ceaseless course, a vast, desolate, and sterile globe. Day and night succeeded one another, and season followed season, while yet no living form existed, and still the sun rose upon arid, verdureless continents, and hot, caldron-like seas, on which the steaming vapor and heavy fogs sat like an incubus. This is the earliest period of which we glean any positive record, and it is probable that previous to this era the universe was in a state of incandescence, or intense heat, and that by the gradual cooling of the globe, the external surface became hard, and formed a firm crust, in the same manner that molten lead, when exposed to the cold air, hardens on the surface. The vapors which previously floated around this heated mass, in like manner became partially condensed, and gradually accumulating in the hollows, formed the boiling seas which in after ages were destined to be vast receptacles teeming with life. How long such a period continued it is impossible to say, and were we even able to number its years, we should in all probability obtain a total of such magnitude as would render us unable to form any accurate idea of its extent. Our ideas of time, like those of space, are comparative, and so immense was this single period in geological history, that any interval taken from human records would fail to present an adequate idea of it. As might be expected, this era was marked by vast and violent convulsions; volcanoes raged and threw up molten granite, earthquakes heaved and uplifted continents, seas were displaced and inundated the land, and still the earth was enveloped in vapor and mist, arising from the high temperature, and the light most probably penetrated only sufficiently to produce a sickly twilight, while the sun shot lurid rays through the dense and foggy atmosphere. Such a world must have been incompatible with either animal or vegetable life, and we accordingly find no remains of either in the rocks which belong to this early period; their principal characteristic is a highly crystalline appearance, giving strong presumptive evidence of the presence of great heat.