as we now witness in some of the granites, which are mixtures of quartz, feldspar, and mica; or the syenites, which are mixtures of quartz, feldspar, and hornblende; or the diorites, which are mostly mixtures of feldspar and hornblende. Or, perchance, the solidification took place under such circumstances that the crystallization was more obscure, as in the various dolerites, which every one admits to have been born of fire. We say that the process of refrigeration must have resulted in such rocks as these; and it is a curious and instructive fact, that when we turn our attention to an examination of the oldest rocks, we find granites, and syenites, and diorites, and dolerites resting where we expected them, underneath the rocks that came into being after water existed upon the earth, spreading out their bases in every direction, and constituting the very abutment which supports the lithological pile. We thus trace a certain succession of events which must occur in accordance with the established laws of physics, and find the series of sequents confirmed by the facts of the rocks themselves. Though this mode of reasoning is not in the spirit of modern natural science, it must always lead us to the truth if we reason correctly. Nevertheless, it is seldom the case that we are justified in the attempt to predicate the phenomena from the laws which involve them, ast long as it is our privilege to confirm the laws by a study of the phenomena. In the present instance, the history of science shows that the laws were first arrived at by a careful induction from facts; and the little deductive reasoning in which we have indulged is but tracing the thread a little farther back, with the phenomenon it hangs upon all the time in full view.

In the process of refrigeration the stiffening crust would become too large for the nucleus within. This would necessarily result from the more rapid contraction of the more

highly heated portions. If the solid and the molten portions suffered equal losses of heat, the molten, by shrinking the most, became too small for the enveloping crust. The crust, therefore, must wrinkle, to fit the shrinking nucleus. Thus incipient inequalities of the surface began to appear. These were the germs of mountains and of continents. From a new-born wrinkle grew the lofty Cordillera.

a

a

a

Fig. 13. Ideal Section of the Earth in primeval times.
a, a, a. The surface when solidification first commenced.
b, b, b. Wrinkles developed in the crust by the shrink-

age of the nucleus.

A scene of terrific sublimity approaches. As yet no water existed upon the earth. No rain had fallen upon the parched and blackened crust. All the water which now fills the oceans, and the rivers, and the lakes-all which saturates the atmosphere, and the soil, and the rocks-rested then upon the earth as an arid, elastic, invisible vapor, extending an unknown distance into surrounding space. This vapor was not cloudlike, but intensely hot and transparent. It was a gas, like the steam just issuing from the escape-pipe of a steam-boiler. The time had now arrived, however, when the remoter regions. to which this aqueous gas extended began to be so far reduced in temperature as to cause condensation to begin— as the heated steam, rushing from the locomotive, soon.

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 carth. 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.

"The sky is changed! and such a change! Oh, night,
And storm and darkness!"

*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.

CHAPTER VI.

OLD OCEAN COMMENCES WORK.

THOUSAND 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