and, on suffering it to cool under circumstances similar to those in which the rock has been placed, it resumes its rock-like aspect. Marks of heat are all about these granites and their trappean associates. Wherever they have come in contact with rocks of sedimentary origin, the latter are scorched and reddened. In many cases they have been actually fused. A sandstone has been converted into quartz; a shale into a micaceous, semi-crystalline bed; a limestone into statuary marble; and all the vestiges of living forms which these strata inclosed have been withered up and dissipated by the touch of fire.

These underlying crystalline masses are not confined to the deep-seated regions of the earth's crust. We find them. thrusting their heads up through the ruptured strata which repose upon their flanks. Higher even than the highest summits formed by the stratified rocks, these foundation masses rear their bold granite heads. From these cold, serene altitudes they look down with dignified complacence upon the fury of the tempest which brings consternation to the landscape below, but fails to ascend to those frigid, breathless summits which every living thing has equally failed to scale.

Some of these venerable domes were reared before ever a particle of sediment had been produced, or even the world-embracing sea had descended from the regions of space around the earth. From their high stations they have watched the procession of all subsequent events; and, while race after race has appeared and disappeared, they have stood calm spectators, unchanged by the myriad vicissitudes of eternity. Others were still the level floor of the ocean when the oldest sediments began to accumulate upon them. In some subsequent age a mighty force has raised them with their load of sediments above the level of the sea. The tempests of succeeding ages have partially

stripped them of their sedimentary coverings, and they stand revealed to the light of day. In other cases the tension of the upheaved strata has caused them to break along the crest of a new-formed ridge. A chasm, miles in depth, has opened down to the molten rock below. The fiery sea has risen to the lips of the fissure, and even escaped in a consuming and terrific overflow. In other cases such an eruption has occurred beneath the waters of the sea, and an entire oceanic basin has been converted into a seething cauldron, in which fish and oysters, sea-urchins and lobsters, corallines and sea-weeds, have been cooked together in a Titanian dish of soup. Entire races have thus been exterminated; and, when the elements subsided again to a quiet condition, the waters have been repeopled with count-less multitudes of beings exactly adapted to the changed circumstances of the earth-not repetitions of the forms just exterminated, but original conceptions, new ideas from the infinite resources of Nature; and yet not fundamentally different, but united to the old by such an identity of fundamental plan as to convince us that the Intelligence which presided in the former epoch survived the catastrophes which brought death to all terrestrial existence, and continued to prosecute his unchanged purposes through succeeding epochs.

Fig. 10. Fingal's Cave in Staffa, composed of basaltic rocks of igneous origin.

Thus fire and water, in their ever-varying operations, have been the principal agencies by which Nature has wrought out the great physical results upon which we gaze with a familiarity which causes us to forget that these safe and solid foundations on which we build cities, and to which we gain a title with hard-earned gold, are but the ruins of pre-existing hills, and valleys, and plains, in which are entombed the long-forgotten relics of the brute nations which preceded us in the possession of the earth.

H

CHAPTER IV.

THE SOLAR SYSTEM IN A BLAZE.

AVING made a reconnoissance of the vast field which lies before the geological observer, let us ascertain what degree of interest may be derived from a more attentive survey. The ordeal by fire stands first in the order of time. We go back, then, to the molten period of the earth. We plunge into the depths of the past eternity, and behold the terrestial globe glowing with a fervent. heat. What a history to trace from that point of time to this! Continents clothed with verdure, and diversified with mountain, hill, and dale-continents spread out upon a thousand courses of solid masonry-are to be derived from this germinal, incandescent mass. It requires an unusual effort of the imagination to leap from the scenes of a modern landscape to an adequate conception of a naked, tenantless, and molten orb, enveloped in an atmosphere of deadly elements, and totally unlike the present earth save in its spherical form and its yearly journey round the sun. To the eye of imagination, the forests must vanish in smoke; the "cloud-capped towers and gorgeous palaces" of man must crumble to clay, and sand, and loam; man and all living things must desert the earth, and leave it in the motionless and stagnant silence of death; the rivers must dry up in their channels; the ocean must change to vapor, and flee to the upper limits of the air; the rockribbed mountains must yield to the melting touch of fire; and the rigid crust of the earth must dissolve into a yielding and obedient fluid.

Can we place ourselves in view of the scenes which then existed? Creation is in its incipient stages. The long line of events, which is to end in the installation of man in possession of the earth, lies before us. Methods and plans are now to be adopted whose carrying out is to be extended into the distant future, and which shall comprehend and provide for the endless variety of exigencies which are to grow out of the gradual development of the destined order of things. How inadequate would be a human intelligence to an occasion like this! But to the mind of the Infinite Intelligence the whole creation already existed, and not a feature of the original plan has been abandoned in the long process of its actualization.

But whence the state of things which we are proposing to picture? Was this the "beginning?" In truth, we are forced to admit that science authorizes us to predicate a molten condition of the globe as the consequent of a vaporous one. What are the states of matter but the product of temperature and pressure? We style the liquid the natural state of water, because that is its ordinary condition under our own eyes. But where the mean temperature is below the freezing-point, the solid is its ordinary state; and where the mean temperature rises above the boiling-point, the gaseous is its ordinary state. To men who exist (if such there are) where the climatic temperature never rises to the thawing-point, water is known only as ice; it is quarried as a rock; it may be built into temples, or fortifications, or used for sidewalks. Could man exist, on the contrary, where the climatic temperature never falls below the boiling-point of water, this substance would only be known as a gas, like hydrogen or carbonic acid. There are regions where water, and even mercury, maintain the permanent condition of solids. gions where they can exist only as vapor.

There are re

The pressure