The World Before the Deluge

• Report of the Royal Cornwall Polytechnic Society for 1S37. Robert Hunt, in "Memoirs of the Geological Survey of Great Britain," vol. i., p. 433.

THE BEGINNING.

The theory which has been developed, and which considers the earth as an extinct sun, as a star cooled down from its original heated condition, as a nebula, or luminous cloud, which has passed from the gaseous to the solid state — this fine conception, which unites so brilliantly the kindred sciences of astronomy and geology, belongs to the French mathematician, Laplace, the immortal author of the " Me'canique Celeste." The hypothesis of Laplace assigns to the sun, and to all bodies which gravitate in -what Descartes calls his toiirbillon, a common origin. " In the primitive state in which we must suppose the sun to be," he says, " it resembles one of those nebulae which the telescope reveals to us, consisting of a more or less brilliant central nnde2is, surrounded by luminous clouds, which clouds, condensing at the surface, become transformed into a star."

It has been calculated that the centre of the earth has a

temperature of about 195,000^ Cent, a degree of heat which surpasses all that the imagination can conceive. We can have no difficulty in admitting that, at a heat so excessive, all the substances which now enter into the composition of the globe would be reduced to the state of gas or vapour. Our planet, then, must have been originally an aggregation of aeriform fluids — a mass of matter entirely gaseous; and if we reflect that substances in their gaseous state occupy a volume eighteen hundred times larger than when solid, we shall have some conception of the enormous volume of this gaseous mass. It would be 53 large as the sun, which is fourteen hundred thousand times larger than the terrestrial sphere. In Fig. 12 we have attempted to give an idea of the vast difference of volume between the earth in its present solid state and in its primitive gaseous condition. One of the globes. A, represents the former, B the latter. It is simply a comparison of size, which is made the more strikingly apparent by means of these geometrical figures —

G

VI.—The Earth circulating in space in the state of a gaseous star.

THE BEGINNING.

one the twentieth part of an inch in diameter, the other two inches and three quarters. At this excessive temperature the gaseous mass, which we have described, would shine in space as the sun does at the present day; and with the same briUiancy as that with which, to our eyes, the fixed stars and planets shine in the serenity of night, as represented on the

Fig. 12. — Comparative volume of the earth in the gaseous and solid state.

opposite page (Plate VI). Circulating round the sun in obedience to the laws of universal gravitation, this incandescent gaseous mass was necessarily regulated by the laws which govern other material substances. As it got cooler it gradually transferred part of its warmth to the glacial regions of the inter-planetary spaces, in the midst of which it traced the line of its flaming orbit. Consequent on its continual cooling (but at the end of a period of time of which it

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would be impossible, even approximately, to fix the duration), the star, originally gaseous, would attain a liquid state. It would then be considerably diminished in volume.

The laws of mechanics teach us that liquid bodies, when in a state of rotation, assume a spherical form; it is one of the laws of their being, emanating from the Creator, and is due to the force o^ attraction. Thus the Earth takes the spheroidal form, belonging to it, in common with the greater number of the celestial bodies.

The Earth is subject to two distinct movements; namely, a movement of translation round the sun, and a movement of rotation on its own axis — the latter a uniform movement, which produces the regular alternations of days and nights. Mechanics have also established the fact, which is confirmed by experiment, that a fluid mass in motion produces (as the result of the variation of the centrifugal force on its different diameters), a swelling towards the equatorial diameter of the sphere, and a flattening at the poles or extremities of its axis. It is in consequence of this law, that the Earth, when it was in a liquid state, became swollen at the equator, and depressed at its two poles; and that it has passed from its primitive spherical form to the spheroidal — that is, has become flattened at each of its polar extremities, and has assumed its present shape of an oblate spheroid.

This bulging at the equator and flattening towards the poles afford the most direct proofs, that can be adduced, of the original liquid state of our planet. A solid and non-elastic sphere — a stone ball, for example — might turn for ages upon its axis, and its form would sustain no change; but a fluid ball, or one of a pasty consistence, would swell out towards the middle, and, in the same proportion, become flattened at the extremities of its axis. It was upon this principle, namely, by admitting the primitive fluidity of the globe, that Newton announced d, priori the bulging of the globe at the equator and its flattening at the poles; and he even calculated the amount of this depression. The actual measurement, both of this expansion and flattening, by Maupertuis, Clairaut, Camus, and Lemonnier, in 1736, proved how exact the calculations of the great geometrican were. Those gentlemen, together with the Abbe Outhier, were sent into Lapland by the Academy of Sciences; the Swedish astronomer, Celsius, accompanied them, and furnished them with the best instruments for measuring and surveying. At the same time the Academy sent Bouguer and Condamine to the equatorial regions of South America. The measurements taken in both these regions established the existence of the equatorial expansion and the polar depression, as Newton had estimated it to be in his calculations.

THE BEGINNING, 8$

It does not follow, as a consequence of the partial cooling down of the terrestrial mass, that all the gaseous substances composing it should pass into a liquid state; some of these might remain in the state of gas or vapour, and form round the terrestrial spheroid an outer envelope or atmosphere (from the Greek words ^t/i^s, vapour^ and c(parLpa, sphere). But we should form a very inexact idea of the atmosphere which surrounded the globe, at this remote period, if we compared it with that which surrounds it now. The extent of the gaseous matter which enveloped the primitive earth must have been immense; it doubtless extended to the moon. It included, in short, in the state of vapour, the enormous body of water which, as such, now constitutes our existing seas, added to all the other substances which preserve their gaseous state at the temperature then exhibited by the incandescent earth; and it is certainly no exaggeration to place this temperature at 2,000° Centigrade. The atmosphere would participate in this temperature; and acted on by such excessive heat, the pressure that it would exert on the Earth would be infinitely greater than that which it exercises at the present time. To the gases which form the component parts of the present atmospheric air — namely, nitrogen, oxygen, and carbonic acid — to enormous masses of watery vapour, must be added vast quantities of mineral substances, metallic or earthy, reduced to a gaseous state, and maintained in that state by the temperature of this gigantic furnace. The metals, the chlorides — metallic, alkaline, and earthy — sulphur, the sulphides, and even the silicates of alumina and lime; all, at this temperature, would exist in a vaporous form in the atmosphere surrounding the primitive globe.

It is to be inferred that, under these circumstances, the different substances composing this atmosphere would be ranged round the globe in the order of their respective densities; the first layer — that nearest to the surface of the globe — being formed of the heavier vapours, such as those of the metals, of iron, platinum, and copper, mixed doubtless with clouds of fine metallic dust produced by the partial condensation of their vapours. This first and heaviest zone, and the thickest also, would be quite opaque, although the surface of the earth was still at a red heat. Above it would come the more vaporisable substances, such as the metallic and alkaline chlorides, particularly the chloride of sodium or common salt, sulphur and phosphorus, with all the volatile combinations of these substances. The upper zone would contain matter still more easily converted into vapour, such as water (steam), together with others naturally gaseous, as oxygen, nitrogen, and carbonic acid. This order of superposition.

S6 THE WORLD BEFORE THE DELUGE.

however, would not always be preserved. In spite of their differences of density, these three atmospheric layers would often become mixed, producing formidable storms and violent ebullitions; frequently throwing down, rending, upheaving, and confounding these incandescent zones.

As to the globe itself, without being so much agitated as its hot and shifting atmosphere, it would be no less subject to perpetual tempests, occasioned by the thousand chemical actions which took place in its molten mass. On the other hand, the electricity resulting from these powerful chemical actions, operating on such a vast scale, would induce frightful electric detonations, thunder adding to the horror of this primitive scene, which no imagination, no human pencil could trace, and which constitutes that gloomy and disastrous chaos of which the legendary history of every ancient race has transmitted the tradition. In this manner would our globe circulate in space, carrying in its train the flaming streaks of its multiple atmosphere, unfitted, as yet, for living beings, and impenetrable to the rays of the sun, around which it described its vast orbit. The temperature of the. planetary regions is infinitely low; according to Laplace it cannot be estimated at less than loo^ below zero. The glacial regions traversed in its course by the incandescent globe would necessarily cool it, at first superficially, when it would assume a pasty consistence. It must not be forgotten that the earth, on account of its liquid state, would be obedient in all its mass to the action of flux and reflux, which proceeds from the attraction of the sun and moon, but to which the sea alone is now subject. This action, to which all its liquid and movable particles were subject, would singularly accelerate the commencement of the solidification of the terrestrial mass. It would thus gradually assume that sort of consistence which iron attains, when it is first withdrawn from the furnace, in the process of puddHng.

As the earth cooled, beds of concrete substances would necessarily be formed, which, floating at first in isolated masses on the surface of the semi-fluid matter, would in course of time come together, consolidate, and form continuous banks; just as we see with the ice of the present Polar Seas, which, when brought in contact by the agitation of the waves, coalesces and forms icebergs, more or less movable. By extending this phenomenon to the whole surface of the globe, the solidification of its entire surface would be produced. A solid, but still thin and fragile crust, would thus envelop the whole earth, enclosing entirely its still fluid interior.

THE BEGINNING.

The entire consolidation would necessarily be a much slower process — one which, according to the received hypothesis, isvery far from being completed at the present time; for it is estimated that the actual thickness of the earth's crust does not exceed thirty miles, while the mean radius or distance from the centre of the terrestrial sphere, approaches 4,000 miles, the mean diameter