Theory of the Earth Volume Ii Part 19

CHAP. XIV.

_Summary of the Doctrine which has been now Ill.u.s.trated._

The system of this earth appears to comprehend many different operations; and it exhibits various powers co-operating for the production of those effects which we perceive. Of this we are informed by studying natural appearances; and in this manner we are led to understand the nature of things, in knowing causes.

That our land, which is now above the level of the sea, had been formerly under water, is a fact for which there is every where the testimony of a mult.i.tude of observations. This indeed is a fact which is admitted upon all hands; it is a fact upon which the speculations of philosophers have been already much employed; but it is a fact still more important, in my opinion, than it has been ever yet considered.

It is not, however, as a solitary fact that any rational system may be founded upon this truth, That the earth had been formerly at the bottom of the sea; we must also see the nature and const.i.tution of this earth as necessarily subsisting in continual change; and we must see the means employed by nature for constructing a continent of solid land in the fluid bosom of the deep. It is then that we may judge of that design, by finding ends and means contrived in wisdom, that is to say, properly adapted to each other.

We have now given a theory founded upon the actual state of this earth, and the appearances of things, so far as they are changing; and we have, in support of that theory, adduced the observations of scientific men, who have carefully examined nature and described things in a manner that is clear and intelligible. We are now to take a review of the principle points on which this theory hangs; and to endeavour to point out the importance of the subject, and the proper manner of judging with regard to a theory of the earth, how far it is conform to the general system of nature, which has for object a world.

If it should be admitted, that this earth had been formed by the collection of materials deposited within the sea, there will then appear to be certain things which ought to be explained by a theory, before that theory be received as belonging to this earth. These are as follows:

_First_, We ought to show how it came about that this whole earth, or by far the greatest part in all the quarters of the globe, had been formed of transported materials collected together in the sea. It must be here remembered, that the highest of our mountainous countries are equally formed of those travelled materials as are the lowest of our plains; we are not therefore to have recourse to any thing that we see at present for the origin of those materials which actually compose the earth; and we must show from whence had come those travelled materials, manufactured by water, which were employed in composing the highest places of our land.

_Secondly_, We must explain how those loose and incoherent materials had been consolidated, as we find they are at present. We are not here to allow ourselves the liberty, which naturalists have a.s.sumed without the least foundation, of explaining every thing of this sort by _infiltration_, a term in this case expressing nothing but our ignorance.

_Thirdly_, The strata are not always equally consolidated. We often find contiguous strata in very different states with respect to solidity; and sometimes the most solid ma.s.ses are found involved in the most porous substance. Some explanation surely would be expected for this appearance, which is of a nature so conclusive as ought to attract the attention of a theorist.

_Fourthly_, It is not sufficient to show how the earth in general had been consolidated; we must also explain, how it comes to pa.s.s that the consolidated bodies are always broken and intersected by veins and fissures. In this case, the reason commonly given, that the earth exposed to the atmosphere had shrunk like moist clay, or contracted by the operation of drying, can only show that such naturalists have thought but little upon the subject. The effect in no shape or degree corresponds to that cause; and veins and fissures, in the solid bodies, are no less frequent under the level of the sea, than on the summits of our mountains.

_Fifthly_, Having found a cause for the fracture and separation of the solid ma.s.ses, we must also tell from whence the matter with which those chasms are filled, matter which is foreign both to the earth and sea, had been introduced into the veins that intersect the strata. If we fail in this particular, What credit could be given to such hypotheses as are contrived for the explanation of more ambiguous appearances, even when those suppositions should appear most probable?

_Sixthly_, Supposing that hitherto every thing had been explained in the most satisfactory manner, the most important appearances of our earth still remain to be considered. We find those strata that were originally formed continuous in their substance, and horizontal in their position, now broken, bended, and inclined, in every manner and degree; we must give some reason in our theory for such a general changed state and disposition of things; and we must tell by what power this event, whether accidental or intended, had been brought about.

_Lastly_, Whatever powers had been employed in preparing land, while situated under water, or at the bottom of the sea, the most powerful operation yet remains to be explained; this is the means by which the lowest surface of the solid globe was made to be the highest upon the earth. Unless we can show a power of sufficient force, and placed in a proper situation for that purpose, our theory would go for nothing, among people who investigate the nature of things, and who, founding on experience, reason by induction from effect to cause.

Nothing can be admitted as a theory of the earth which does not, in a satisfactory manner, give the efficient causes for all these effects already enumerated. For, as things are universally to be acknowledged in the earth, it is essential in a theory to explain those natural appearances.

But this is not all. We live in a world where order every where prevails; and where final causes are as well known, at least, as those which are efficient. The muscles, for example, by which I move my fingers when I write, are no more the efficient cause of that motion, than this motion is the final cause for which the muscles had been made.

Thus, the circulation of the blood is the efficient cause of life; but, life is the final cause, not only for the circulation of the blood, but for the revolution of the globe: Without a central luminary, and a revolution of the planetary body, there could not have been a living creature upon the face of this earth; and, while we see a living system on this earth, we must acknowledge, that in the solar system we see a final cause.

Now, in a theory which considers this earth as placed in a system of things where ends are at least attained, if not contrived in wisdom, final causes must appear to be an object of consideration, as well as those which are efficient. A living world is evidently an object in the design of things, by whatever Being those things had been designed, and however either wisdom or folly may appear in that design. Therefore the explanation, which is given of the different phenomena of the earth, must be consistent with the actual const.i.tution of this earth as a living world, that is, a world maintaining a system of living animals and plants.

Not only are no powers to be employed that are not natural to the globe, no action to be admitted of except those of which we know the principle, and no extraordinary events to be alledged in order to explain a common appearance, the powers of nature are not to be employed in order to destroy the very object of those powers; we are not to make nature act in violation to that order which we actually observe, and in subversion of that end which is to be perceived in the system of created things. In whatever manner, therefore, we are to employ the great agents, fire and water, for producing those things which appear, it ought to be in such a way as is consistent with the propagation of plants and life of animals upon the surface of the earth. Chaos and confusion are not to be introduced into the order of nature, because certain things appear to our partial views as being in some disorder. Nor are we to proceed in feigning causes, when those seem insufficient which occur in our experience.

Animal life being thus considered as an object in the view of nature, we are to consider this earth as being the means appointed for that end; and then the question is suggested, How far wisdom may appear in the const.i.tution of this earth, as being _means_ properly adapted to the system of animal life, which is evidently the end. This is taking for granted, that there is a known system of the earth which is to be tried--how far properly adapted to the end intended in nature. But, it is this very system of the earth which is here the subject of investigation; and, it is in order to discover the _true system_ that we are to examine, by means of final causes, every theory which pretends to show the nature of that system, or to a.s.sign efficient causes to physical events.

Here then we have a rule to try the propriety of every operation which should be acknowledged as in the system of nature, or as belonging to the theory of this earth. It is not necessary that we should see the propriety of every natural operation; our natural ignorance precludes us from any t.i.tle to form a judgment in things of which we are not properly informed; but, no suppositions of events, or explanations of natural appearances, are to be admitted into our Theory, if the propriety of those alledged operations is not made to appear. We are now to make an application.

This earth, which is now dry land, was under water, and was formed in the sea. Here is a matter of fact, and not of theory, so far as it can be made as evident as any thing of which we have not seen the immediate act or execution. But the propriety of this matter of fact is only to be perceived in making the following acknowledgment, That the origin of this earth is necessarily placed in the bottom of the sea. In supposing any other origin to this habitable earth, we would see the impropriety of having it covered with water, or drowned in the sea. But, being formed originally at the bottom of the sea, if we can explain the phenomena of this earth by natural causes, we will acknowledge the wisdom of those means, by which the earth, thus formed at the bottom of the sea, had been perfected in its nature, and made to fulfil the purpose of its intention, by being placed in the atmosphere.

If the habitable earth does not take its origin in the waters of the sea, the was.h.i.+ng away of the matter of this earth into the sea would put a period to the existence of that system which forms the admirable const.i.tution of this living world. But, if the origin of this earth is founded in the sea, the matter which is washed from our land is only proceeding in the order of the system; and thus no change would be made in the general system of this world, although this particular earth, which we possess at present, should in the course of nature disappear.

It has already been our business to show that the land is actually wasted universally, and carried away into the sea. Now, What is the final cause of this event?--Is it in order to destroy the system of this living world, that the operations of nature are thus disposed upon the surface of this earth? Or, Is it to perpetuate the progress of that system, which, in other respects, appears to be contrived with so much wisdom? Here are questions which a Theory of the Earth must solve; and here indeed, must be found the most material part by far of any Theory of the Earth. For, as we are more immediately concerned with the operations of the surface, it is the revolutions of that surface which forms, for us, the most interesting subject of inquiry.

Thus we are led to inquire into the final cause of things, while we investigate an operation of such magnitude and importance, as is that of forming land of sea, and sea of land, of apparently reversing nature, and of destroying that which is so admirably adapted to its purpose. Was it the work of accident, or effect of an occasional transaction, that by which the sea had covered our land? Or, Was it the intention of that Mind which formed the matter of this globe, which endued that matter with its active and its pa.s.sive powers, and which placed it with so much wisdom among a numberless collection of bodies, all moving in a system?

If we admit the first, the consequence of such a supposition would be to attribute to chance the const.i.tution of this world, in which the systems of life and sense, of reason and intellect, are necessarily maintained.

If again we shall admit, that there is intention in the cause by which the present earth had been removed from the bottom of the sea, we may then inquire into the nature of that system in which a habitable earth, possessed of beauty, arranged in order, and preserved with economy, had been formed by the mixture and combination of the different elements, and made to rise out of the wreck of a former world.

In examining the structure of our earth, we find it no less evidently formed of loose and incoherent materials, than that those materials had been collected from different parts, and gathered together at the bottom of the sea. Consequently, if this continent of land, first collected in the sea, and then raised above its surface, is to remain a habitable earth, and to resist the moving waters of the globe, certain degrees of solidity or consolidation must be given to that collection of loose materials; and certain degrees of hardness must be given to bodies which were soft or incoherent, and consequently so extremely perishable in the situation where they now are placed.

But, at the same time that this earth must have solidity and hardness to resist the sudden changes which its moving fluids would occasion, it must be made subject to decay and, waste upon the surface exposed to the atmosphere; for, such an earth as were made incapable of change, or not subject to decay, could not afford that fertile soil which is required in the system of this world, a soil on which depends the growth of plants and life of animals,--the end of its intention.

Now, we find this earth endued precisely with that degree of hardness and consolidation, as qualifies it at the same time to be a fruitful earth, and to maintain its station with all the permanency compatible with the nature of things, which are not formed to remain unchangeable.

Thus we have a view of the most perfect wisdom, in the contrivance of that const.i.tution by which the earth is made to answer, in the best manner possible, the purpose of its intention, that is, to maintain and perpetuate a system of vegetation, or the various race of useful plants, and a system of living animals, which are in their turn subservient to a system still infinitely more important, I mean, a system of intellect.

Without fertility in the earth, many races of plants and animals would soon perish, or be extinct; and, without permanency in our land, it were impossible for the various tribes of plants and animals to be dispersed over all the surface of a changing earth. The fact is, that fertility, adequate to the various ends in view, is found in all the quarters of the world, or in every country of the earth; and, the permanency of our land is such, as to make it appear unalterable to mankind in general, and even to impose upon men of science, who have endeavoured to persuade us that this earth is not to change. Nothing but supreme power and wisdom could have reconciled those two opposite ends of intention, so as both to be equally pursued in the system of nature, and both so equally attained as to be imperceptible to common observation, and at the same time a proper object for the human understanding.

We thus are led to inquire into the efficient causes of this const.i.tution of things, by which solidity and stability had been bestowed upon a ma.s.s of loose materials, and by which this solid earth, formed first at the bottom of the sea, had been placed in the atmosphere, where plants and animals find the necessary conditions of their life.

Now, we have shown, that subterraneous fire and heat had been employed in the consolidation of our earth, and in the erection of that consolidated body into the place of land. The prejudices of mankind, who cannot see the steps by which we come at this conclusion, are against the doctrine; but, prejudice must give way to evidence. No other Theory will in any degree explain appearances, while almost every appearance is easily explained by this Theory.

We do not dispute the chymical action and efficacy of water, or any other substance which is found among the materials collected at the bottom of the sea; we only mean to affirm, that every action of this kind is incapable of producing perfect solidity in the body of earth in that situation of things, whatever time should be allowed for that operation, and that whatever may have been the operations of water, aided by fire, and evaporated by heat, the various appearances of mineralization, (every where presented to us in the solid earth, and the most perfect objects of examination), are plainly inexplicable upon the principle of aqueous solution. On the other hand, the operation of heat, melting incoherent bodies, and introducing softness into rigid substances which are to be united, is not only a cause which is proper to explain the effects in question, but also appears, from a mult.i.tude of different circ.u.mstances, to have been actually exerted among the consolidated bodies of our earth, and in the mineral veins with which the solid bodies of the earth abound.

The doctrine, therefore, of our Theory is briefly this, That, whatever may have been the operation of dissolving water, and the chymical action of it upon the materials acc.u.mulated at the bottom of the sea, the general solidity of that ma.s.s of earth, and the placing of it in the atmosphere above the surface of the sea, has been the immediate operation of fire or heat melting and expanding bodies. Here is a proposition which may be tried, in applying it to all the phenomena of the mineral region; so far as I have seen, it is perfectly verified in that application.

We have another proposition in our Theory; one which is still more interesting to consider. It is this, That as, in the mineral regions, the loose or incoherent materials of our land had been consolidated by the action of heat; so, upon the surface of this earth exposed to the fluid elements of air and water, there is a necessary principle of dissolution and decay, for that consolidated earth which from the mineral region is exposed to the day. The solid body being thus gradually impaired, there are moving powers continually employed, by which the summits of our land are constantly degraded, and the materials of this decaying surface travelled towards the coast. There are other powers which act upon the sh.o.r.e, by which the coast is necessarily impaired, and our land subjected to the perpetual incroachment of the ocean.

Here is a part of the Theory with which every appearance of the surface may be compared. I am confident that it will stand the test of the most rigid examination; and that nothing but the most inconsiderate judgment may mistake a few appearances, which, when properly understood, instead of forming any subject of objection to the Theory, will be found to afford it every reasonable support or confirmation.

We have now seen, that in every quarter of the globe, and in every climate of the earth, there is formed, by means of the decay of solid rocks, and by the transportation of those moveable materials, that beautiful system of mountains and valleys, of hills and plains, covered with growing plants, and inhabited by animals. We have seen, that, with this system of animal and vegetable economy, which depends on soil and climate, there is also a system of moving water, poured upon the surface of the earth[30], in the most beneficial manner possible for the use of vegetation, and the preservation of our soil; and that this water is gathered together again by running to the lowest place, in order to avoid acc.u.mulation of water upon the surface, which would be noxious.

[Footnote 30: See Dissertations upon Subjects of Natural Philosophy, Part I.]

It is in this manner that we first have streams or torrents, which only run in times of rain. But the rain-water absorbed into the earth is made to issue out in springs, which run perpetually, and which, gathering together as they run, form rivulets, watering valleys, and delighting the various inhabitants of this earth. The rivulets again are united in their turn, and form those rivers which overflow our plains, and which alternately bring permanent fertility and casual devastation to our land. Those rivers, augmenting in their volume as they unite, pour at last their mighty waters into the ocean; and thus is completed that circulation of wholesome fluids, which the earth requires in order to be a habitable world.

Our Theory farther shows, that in the ocean there is a system of animals which have contributed so materially to the formation of our land. These animals are necessarily maintained by the vegetable provision, which is returned in the rivers to the sea, and which the land alone or princ.i.p.ally produces. Thus we may perceive the mutual dependence upon each other of those two habitable worlds,--the fluid ocean and the fertile earth.

The land is formed in the sea, and in great part by inhabitants of that fluid world. But those animals, which form with their _exuviae_ such a portion of the land, are maintained, like those upon the surface of the earth, by the produce of that land to which they formerly had contributed. Thus the vegetable matter, which is produced upon the surface of the earth in such abundance for the use of animals, and which, in such various shapes, is carried by the rivers into the sea, there sustains that living system which is daily employed to make materials for a future land.

Here is a compound system of things, forming together one whole living world; a world maintaining an almost endless diversity of plants and animals, by the disposition of its various parrs, and by the circulation of its different kinds of matter. Now, we are to examine into the necessary consequence of this disposition of things, where the matter of this active world is perpetually moved, in that salutary circulation by which provision is so wisely made for the growth and prosperity of plants, and for the life and comfort of its various animals.

If, in examining this subject, we shall find that there is nothing in the system but what is necessary, that is, nothing in the means employed but what the importance of the end requires; if we shall find that the end is steadily pursued, and that there is no deficiency in the means which are employed; and if it shall be acknowledged that the end which is attained is not idle or insignificant, we then may draw this conclusion, That such a system is in perfect wisdom; and therefore that this system, so far as it is found corresponding properly with natural appearances, is the system of nature, and not the creature of imagination.

Let us then take a cursory view of this system of things, upon which we have proceeded in our theory, and upon which the const.i.tution of this world seems to depend.

Our solid earth is every where wasted, where exposed to the day. The summits of the mountains are necessarily degraded. The solid and weighty materials of those mountains are every where urged through the valleys, by the force of running water. The soil, which is produced in the destruction of the solid earth, is gradually travelled by the moving water, but is constantly supplying vegetation with its necessary aid.

This travelled soil is at last deposited upon the coast, where it forms most fertile countries. But the billows of the ocean agitate the loose materials upon the sh.o.r.e, and wear away the coast, with the endless repet.i.tions of this act of power, or this imparted force. Thus the continent of our earth, sapped in its foundation, is carried away into the deep, and sunk again at the bottom of the sea, from whence it had originated.

We are thus led to see a circulation in the matter of this globe, and a system of beautiful economy in the works of nature. This earth, like the body of an animal, is wasted at the same time that it is repaired. It has a state of growth and augmentation; it has another state, which is that of diminution and decay. This world is thus destroyed in one part, but it is renewed in another; and the operations by which this world is thus constantly renewed, are as evident to the scientific eye, as are those in which it is necessarily destroyed. The marks of the internal fire, by which the rocks, beneath the sea are hardened, and by which the land is produced above the surface of the sea, have nothing in them which is doubtful or ambiguous. The destroying operations again, though placed within the reach of our examination, and evident almost to every observer, are no more acknowledged by mankind, than is that system of renovation which philosophy alone discovers.

It is only in science that any question concerning the origin and end of things is formed; and it is in science only that the resolution of those questions is to be attained. The natural operations of this globe, by which the size and shape of our land are changed, are so slow as to be altogether imperceptible to men who are employed in pursuing the various occupations of life and literature. We must not ask the industrious inhabitant, for the end or origin of this earth: he sees the present, and he looks no farther into the works of time than his experience can supply his reason. We must not ask the statesman, who looks into the history of time past, for the rise and fall of empires; he proceeds upon the idea of a stationary earth, and most justly has respect to nothing but the influence of moral causes.

It is in the philosophy of nature that the natural history of this earth is to be studied; and we must not allow ourselves ever to reason without proper data, or to fabricate a system of apparent wisdom in the folly of a hypothetical delusion.

When, to a scientific view of the subject, we join the proof which has been given, that in all the quarters of the globe, in every place upon the surface of the earth, there are the most undoubted marks of the continued progress of those operations which wear away and waste the land, both in its height and width, its elevation and extention, and that for a s.p.a.ce of duration in which our measures of time are lost, we must sit down contented with this limitation of our retrospect, as well as prospect, and acknowledge, that it is in vain to seek for any computation of the time, during which the materials of this earth had been prepared in a preceding world, and collected at the bottom of a former sea.