cools into a cloud of visible mist. An intelligence located upon our earth at this epoch would have seen the dusky atmosphere begin to thicken. In the far-off regions, wisps of vapor crept along the sky, as cirrhi in our day foretoken the gathering storm. They grew, and thickened, and darkened till a pall of impending clouds enwrapped the earth, and the light of sun, and moon, and star was shut out for a geological age. Particle drew particle to itself, and rain-drops began to precipitate themselves through the lower strata of the fervid atmosphere. In their descent they were scorched to evaporation, as the meteor's light vanishes in mid-heaven. The vapors, hurrying back to the bosom of the cloud, were again sent forth, again to be consumed. At length they reached the fervid crust, but only to be exploded into vapor and driven back to the overburdened cloud, which had an ocean to transfer to the earth. The clouds poured the ocean continually forth, and the seething crust continually rejected the offering. The field between the cloud and the earth was one stupendous scene of ebullition.* But the descent of rains and the ascent of vapors disturbed the electricities of the elements. In the midst of this cosmical contest between fire and water, the voices of heaven's artillery were heard. Lightnings darted through the Cimmerian gloom, and world-convulsing thunders echoed through the universe. 66 The sky is changed! and such a change! Oh, night, * Those who are acquainted with Figuier's interesting works will note a remarkable correspondence between his treatment of this subject and my own. It is but justice, therefore, to state that these chapters were drawn up long before the work of Figuier appeared. This, indeed, has been my conception of these primeval scenes since 1856; and it was in print in 1857. ᏟᎻᎪᏢᎢᎬᎡ ᏙᏞ OLD OCEAN COMMENCES WORK. ATHOUSAND years of storm and lightning have passed, and the primeval tempest is drawing to a close. The waters are now permitted to rest upon the surface. By degrees the clouds are exhausted, and sunlight filters through the thinned envelope. As the morning of another geological epoch dawns, it reveals the change of scene. The surface which, in the preceding age, was scorched and arid, is now a universal sea of tepid waters. The earliest ocean enveloped the earth on every hand. A few isolated granite summits perhaps protruded above the watery waste. Around their bases careered the surges which gnawed at their foundations. Geology is unable to aver that any of them survived the denudations of this first detrital period. The demands of nature for material from which to lay the thick and massive foundations of the stratified pile of rocks were enormous, and it is probable that whole mountains were quarried level by the energies of this young, fresh, and all-embracing ocean. Probably, however, the nuclei of some of our oldest mountain masses, though subsequently elevated to their present altitudes, may be regarded as the remnants of the granite knobs that reared their frowning and angular visages above the primordial deep. If so, the erosion of the waves and the battering of the tempests have given to their sides and heads a smooth and bald rotundity. But most, if not all of the original pinnacles of the earth's crust have been leveled to the water's surface and spread over the floor of the sea. To-day we may gather up the fragments, not from the bottom of the sea, but raised again mountain high, or incorporated into the fabric of new-built continents! Sublime ruins! What are the marbles of Nineveh, or the columns of the Parthenon, in comparison with these hoary relics of Nature's primeval structures? I said that the fury of the waves strewed the ocean's bed with the ruins of these ancient islands. This is no fancy. The demonstration is before our eyes. The floor of the sea was first formed of rocks that had cooled from a state of fusion. The few islands that existed were but exposed portions of this floor. The débris scattered over this foundation would be arranged in layers, as water always ar ranges its sediments. The coarser materials would be transported by the more powerful action and deposited in one place; the finer materials would be carried beyond by Fig. 15. Shore Erosion and Distribution of Sediments. C. a, a. The primordial igneous crust. b. A sea-side cliff gnawed by the waves. The ordinary sea-level. d. The ruins of the cliff-the coarser deposited near the shore, and the finer floated to greater depths. the feebler agency, and deposited in a remoter region. Thus some of the first-formed strata would be finer and others would be coarser; but all must be composed of materials derived from the pre-existing rocks. This deduction is again corroborated by well-known facts. Every where do we find reposing upon the ancient igneous floor a bed of stratified materials composed of the same constituent minerals as the rocks they rest upon. For instance, granite is very commonly the foundation rock; but immediately upon this repose thick beds of gneissoid rocks. Now gneiss, like granite, is composed of quartz, feldspar, and mica, and differs only in this-that the constituents have been broken up, assorted by water, and redeposited in regular layers. As we have different varieties of granitoid rocks, so we have corresponding varieties of gneissoid rocks, differing from the former only in being stratified. So general and so well recognized is this phenomenon, that Sir Roderick I. Murchison, an eminent geological authority, designates these lower strata beds of "fundamental gneiss." This occurrence of gneiss, every where reposing upon granite, is a most interesting and instructive. fact, and confirms all that I have said of the denudation of the primitive islands, and the universality of the primitive sea. But, though gneiss is generally the foundation stratum, we find abundance of other rocks either reposing upon the gneiss, or interstratified with it in the lower portions of the sedimentary series. Undoubtedly some of these have resulted from the impalpable powder to which long-continued attrition reduced some portions of the primitive granite, transported to the remotest and quietest portions of the ocean, and there allowed to subside. But we know also that others of the oldest strata associated with the gneisses have been the results of chemical agencies. This is one of the revelations of modern chemical geology, which no name has more adorned than that of Dr. T. Sterry Hunt, of the Geological Commission of the Dominion of Canada. According to Hunt and Logan, the limestones of this early period could have had no other than a chemical origin. Common limestone is composed, as every one knows, of carbonic acid and lime. Heat, as the manufacturer of lime |