Chapter I (4)

«Cette chaîne extérieure des _Alpes_ évidemment d'origine _marine_, a cependant des caractères qui la distinguent de la plupart des autres montagnes de la même classe; et ces caractères semblent annoncer plus d'antiquité. Je crois d'abord pouvoir les regarder comme les montagnes _secondaires_ les plus hautes de notre continent. (Je ne parle ici que des montagnes marines.) Ensuite leur destruction est beaucoup plus grande que celle d'aucune autre montagne de ce genre qui me soit connue: car elles sont presque aussi couronnées de pics que les _Alpes primordiales_; et ces _pics_, étant par _couches_, montrent des restes d'anciens sommets qui devoient avoir une grande étendue. Ce qui, joint à quelques dérangemens dans leurs couches, paroît indiquer que ces montagnes ont été exposées plus longtemps que la plupart des autres montagnes _secondaires_, aux revolutions qu'essuyoit le fond de la _mer_; et qu'elles en sont sorties déjà fort altérées.»

There is at present no question concerning the particular shape in which the mountains of the earth had come out of the waters of the sea. We are considering the wasting of those mountains, in being exposed to the atmosphere and waters of the earth; and the operation that the sea may have had upon their surface, is a subject for judging of which we have not the smallest data, unless by taking the thing for granted, or supposing that the present state of things is that former shape after which we inquire. Now, this is a species of reasoning that M. de Luc would certainly explode; for he admits, as we shall afterwards find, great changes among the mountains of the Alps, from the influences of the atmosphere, perhaps more rapid changes than we are disposed to allow. Therefore, to call in the aid of the ocean, for the degradation of these secondary calcareous mountains, holds of no reason that I can see, unless it be that of diminishing the time which otherwise would have been required in bringing about those changes by the atmosphere alone.

To conclude: Whether we examine the mountain or the plain; whether we consider the degradation of the rocks, or the softer strata of the earth; whether we contemplate nature, and the operations of time, upon the shores of the sea, or in the middle of the continent, in fertile countries, or in barren deserts, we shall find the evidence of a general dissolution on the surface of the earth, and of decay among the hard and solid bodies of the globe; and we shall be convinced, by a careful examination, that there is a gradual destruction of every thing which comes to the view of man, and of every thing that might serve as a resting place for animals above the surface of the sea.

CHAP. V.

_Facts in confirmation of the Theory respecting the Operations of the Earth employed in forming Soil for Plants._

I have distinguished the mineral operations of the earth, by which solid bodies are formed of loose materials, as well as the resolving or decomposing operations which are proper to the surface exposed to the sun and atmosphere. I have also pointed out the end or intention of those several operations, and likewise the means by which they have been brought about. We may now turn our view to that part of the system in which an indefinite variety of soils, for the growth of plants and life of animals, is to be provided upon the face of the earth, corresponding to that diversity which, in the wisdom of nature, has been made of climates.

In this last view, now to be considered, some confirmation should be given to the Theory, in finding the soil, or travelled materials upon the surface of the land, composed of earth, that is, of sand and clay, of stones and gravel; the earth and stones as arising from the resolution and separation of the solids in the neighbourhood of the place; the gravel, again, as having often travelled from more distant parts.

It would be very improper to adduce any example of a particular, where the force of the argument lies in the generality alone. It is enough to have mentioned the facts which are to be examined: Every person of inquiry and observation will judge for himself how far those facts are true.

But there is one general remark that may be made on this occasion, where the operations of the surface are concerned, and which may assist the investigation of this subject; it is with regard to the gravel or stones worn by attrition, which may have come from a distance. In proportion as hard and insoluble stones are near to their natural beds, they will be found with the sharp angles of their fracture, unless there may have been a cause of agitation and attrition on the spot; they will also be in greater quantity, _cet. par._ in this place; whereas the farther they may have travelled, they will naturally incline to be more rounded, and, in equal circumstances, will always be more scarce.

We have thus principles by which to judge of every appearance in relation to the travelled materials of our soil. When, for example, we find an immense quantity of the hardest stones worn round by attrition, and collected not far distant from their native place, we cannot suppose that they have acquired their shape by the attrition in the distance they have travelled, but in an agitation which they must have received nearly in the place from whence they came. Such is the gravel in the chalk country of England. Around London, in all directions, immense quantities of gravel are round, which consists almost entirely of flint worn or rounded by attrition; but this is the very centre of the chalk country, at least of England; and no doubt the same appearances will be found in France. We must therefore conclude, that the south of England was under water when that gravel was formed; and that immense quantities of the chalk above had been destroyed by the agitation of the sea in preparing such quantities of gravel which still remain upon the land; besides the immense quantities which must have been dispersed all around during the operation, as well as carried into the sea by the rivers since the elevation of our land. It is not uncommon to find this gravel twenty or thirty feet deep; and masses are found of much greater thickness. Were these masses of gravel formed in a deep hollow place, they would draw to no conclusion beyond the appearance itself; but they are, on the contrary, in form of hills; and therefore they serve as a kind of measure or indication of what had been carried away when these were left remaining.

We may observe a series or a progress in those forming and destroying operations, by which, on the one hand, the flinty bodies, already formed in the mineral region, were again destroyed, in being diminished by their mutual attrition; and, on the other hand, those diminished bodies were again consolidated into one mass of flinty stone, without the smallest pore or interstice. This example is to be found in the puddingstone of England. It consists of flint pebbles, precisely like Kensington gravel, penetrated or perfectly consolidated by a flinty substance. Here are the two opposite processes of the globe carried on at the same time and nearly in the same place. But it must be considered, that our land was then in the state of emerging from the sea, and those operations of subterranean fire fit for elevating land was then no doubt exerted with great energy; at present, no such thing appears in this place. But, from the momentary views we have of things, it would be most unphilosophical to draw such absolute conclusions.

The argument now employed rests upon the identity of the substance of the gravel with that of the entire flint, which is found in the chalk country; and it goes to prove that the sea had worn away a great deal of that chalk country above the place upon which this body of gravel is now resting; consequently that the sea had formerly flowed over that country covered with gravel, and had dispersed much of that gravel in transporting it to other regions, where that species of flint was not naturally produced. By a parity of reasoning, the gravel produced in the neighbouring regions, and which would be proper to those places, as consisting of their peculiar productions, must have been likewise dispersed and mixed with the surrounding bodies of gravel. But as in the country of which we are now treating, there are considerable regions, the different productions of which are perfectly distinct, we have a proper opportunity of bringing those conclusions of the theory to the test of observation.

For this purpose, let us examine the different countries which surround the chalk regions of England, France, and Flanders; if the gravel upon those neighbouring countries contain flint which the country does not naturally produce; and if the mixture of this flint among the gravel, which is proper to the country itself, be with regard to quantity in proportion to the vicinity of the flint country, the Theory will then be confirmed; and there is no doubt that this is so. On the other hand, let us examine the gravel about London, which is far distant from any place that produces quartz; if we shall find a very small proportion of quartz gravel in this flinty soil, we may be assured that the quartz has travelled from a distance, and that the Theory is thus approved. This is actually the case, and I have seen puddingstone containing quartz gravel among the flint.

In confirmation of this view of the travelled soil, it may be observed, that in lower Saxony about Hamburgh, and for a great way to the south-west, the gravel is mostly of broken flint, such as is around the chalk countries: Yet it is at a distance from the chalk of Flanders; there is however at Luxemburgh chalk with flint, the same as in England and France. Therefore the flinty soil of that country, in like manner, demonstrates the great destruction of the solid parts, and illustrates the formation of soil by the remainder of the hard parts below, and the alluvion of other parts.

There is most undoubted evidence that the solid body of our land had been formed at the bottom of the sea, and afterwards raised above the surface of the water; but, in the case which has now been described, it appears that the travelled soil of the surface of our land had been lately under the surface of the sea. We have thus therefore traced the different steps in the operations of nature, of which the last step may be considered as thus exposed to our view almost as much as the operations of man in building the Pyramids of Egypt. But surely there are other documents to be found in examining the different coasts of this island with attention; and there must be a consistency in the general appearance which never fails to attend on truth.

From the south to the north of this island, there are, in many places, the most evident marks of the sea having been upon a higher level on the land; this height seems to me to amount to about 40 or 50 feet perpendicular at least, which the land must have been raised. Some of those facts may now be mentioned.

Upon the banks of the Thames, I have found sea shells in the travelled soil a considerable height above the level of the sea. In low Suffolk there are great bodies of sea shells found in the soil which the farmers call _crag,_ and with it manure their land. I do not know precisely the height above the sea; but I suppose it cannot exceed 100 feet. In the Frith of Forth there are, in certain places, particularly about Newhaven, the most perfect evidence of a sea bank, where the washing of the sea had worn the land, upon a higher level than the present. The same appearance is to be found at Ely upon the Fife coast, where the sea had washed out grottos in the rocks; and above Kinneel, there is a bed of oyster shells some feet deep appearing in the side of the bank, about 20 or 30 feet above the level of the sea, which corresponds with the old sea banks. I have seen the same evidence in the Frith of Cromarty, where a body of sea shells, in a similar situation, was found, and employed in manuring the land. There are many other marks of a sea beach upon a higher level than the present, but I mention only those which I can give with certainty.

We have been considering an extensive country more or less covered with gravel; such is England south of Yorkshire; both upon the east and west sides of the island. This country having no high mountainous part in the middle, so as to give it a considerable declivity towards the shores and rivers, the gravel has remained in many places, and in some parts of a considerable thickness. But in other parts of the island, where the declivity of the surface favours the transportation of gravel by the currents of water, there is less of the gravel to be found in the soil, and more of the fragments of stone not formed into gravel. Still, however, the same rule holds with regard to tracing the gravel from its source, and finding particular substances among the gravel of every region, in proportion to the quantity of country yielding that substance, and the vicinity to the place from whence it came.

Here are principles established, for the judging of a country, in some respects, from a specimen of its gravel or travelled stones. In this manner, I think, I can undertake to tell from whence had come a specimen of gravel taken up any where, at least upon the east side of this island. Nor will this appear any way difficult, when it is considered, that, from Portland to Caithness or the Orkneys, there are at least ten different productions of hard stone in the solid land which are placed at proper distances, are perfectly distinguishable in the gravel which is formed of them, and with all of which I am well acquainted. Let us suppose the distance to be 600 miles, and this to be divided equally into 10 different regions of 60 miles each, it must be evident that we could not only tell the region, which is knowing within 60 miles of the place, but we could also tell the intermediate space, by seeing an equal mixture of the gravel of two contiguous regions; and this is knowing within 30 miles of the place. If this be allowed, it will not seem difficult to estimate an intermediate distance from the different proportions of the mixed gravel. This is supposing the different regions to be in all respects equal, which is far from being in reality the case; nevertheless, a person well acquainted with the different extent and various natures of those regions, may make allowances for the different known circumstances that must have influenced in those operations, although it is most probable there will be others which must be unknown, and for which he can make no allowance.

The author of the Tableaux de la Suisse has entered very much into this view of things; he has given us some valuable observations in relation to this subject, which I would here beg leave to transcribe[7].

[Footnote 7: Discours sur l'Histoire Naturelle de la Suisse, p. 27.]

«Nous avons dit précédemment que c'étoit entre Orfière et Liddes que nous avions vu les derniers granites roulés, on n'en rencontre plus dans tout le reste de la route jusqu'au haut du Mont St. Bernard. Les rochers qui dominent ce sommet ne sont pas composés de granites, et quoiqu'on ne puisse aborder jusqu'à leur plus grande élévation, on peut juger de leurs espèces, par les masses qui s'en précipitent. D'où peuvent donc provenir ces masses roulées de granites qui se trouvent jetés et répandus sur le penchant et au bas de ce mont? Il y a peut-être quelque montagne ou rocher de granite que nous n'avons pas été à portée de voir: il faudroit plus d'un mois pour faire un pareil examen et parcourir les montagnes environnantes, et faute de pouvoir parvenir à certains sommets, examiner scrupuleusement les fonds pour juger des hauts. De pareilles recherches sont plus difficiles et plus longues qu'on ne le croit communement quand on veut réellement voir et observer. Beaucoup de vallons sont comblés à des hauteurs prodigieuses, par les amas et les débris provenant des montagnes supérieures: ils cessent d'être des vallons, pour former ou faire partie de montagnes. Ces déplacement et des bouleversemens, changeant la direction et le courant des torrens, entraînent dans des parties bien opposées des débris qu'on croiroit devoir chercher et trouver ailleurs. On seroit induit en erreur, en voulant suivre toujours le cours actuel des eaux qui descendent des montagnes. Ce n'est pas dans cette occasion seul mais l'Allemagne, la Corse, la Sardaigne, et beaucoup de pays de hautes montagnes, nous out fourni également des exemples de masses de rochers roulés de différentes espèces dont il n'existoit pas de rochers pareils, dans toutes les parties élevées environnantes, à plusieurs lieues, à plusieurs journées de chemin, et souvent totalement inconnus dans les pays d'alentour. Si nous avons remarqué les même espèces de rochers faisant corps, et attachés au sol, à une ou plusieurs lieues de distance; nous avons vu souvent que des montagnes plus hautes étoient entre ces masses roulées et les rochers, d'ou on auroit pu supposer qu'elles ont été arrachées: il repugne à croire que des masses, d'un poids prodigieux, ayent été transportées et roulées en travers d'un vallon profond, pour remonter et passer de l'autre côté d'une montagne. Nous abandonnons, a ceux qui travaillent dans le cabinet, à l'arrangement du globe, la recherche des moyens que la nature a employé pour produire de pareils effets. Nous nous contenterons, ainsi que nous avons promis, de rendre compte de ce que nous avons vu et observé, et d'engager ceux qui auront la facilité de faire des remarques analogues de constater leurs observations en indiquant toujours les lieux fidèlement, ainsi que nous le faisions pour la Suisse.»

Here the experience of our naturalist amounts to this, that, in those operations by which the solid land is wasted, and the hard materials worn by attrition and transported, it is not always evident from whence had come every particular body of stone or mineral which had travelled by means of water; nor the particular route which, in descending from a higher to a lower place, the protruded body had been made to take, although, in general, these facts may be discovered without much difficulty. Now, this state of things is no other than the natural consequence of the great wasting of the surface and solid parts of our land, and the unequal degradation of this surface, by which means the shape of the earth is so changed, that it would often be impossible, from the present state, to judge of the course in which many bodies had been travelled by water.

M. de Saussure has described a very curious appearance of this kind: It is the finding the travelled materials of Mont Blanc, or fragments detached from the summit and centre of the Alps, in such places as give reason to conclude that they had passed through certain openings between the mountains of the Jura. This is a thing which he thinks could not happen according to the ordinary course of nature; he therefore ascribes this appearance to some vast _debacle_, or general flood, which had with great impetuosity transported all at once those heavy bodies, in the direction of that great current, through the defiles of the Alps, or the openings of those mountains.

In giving this beautiful example of the wasting and transporting operations of this earth, this naturalist overlooks the principles which I would wish to inculcate; and he considers the surface of the earth, in its present state, as being the same with that which had subsisted while those stones had been transported. Now, upon that supposition, the appearances are inexplicable; for, How transport those materials, for example, across the lake of Geneva? But there is no occasion to have recourse to any extraordinary cause for this explanation; it must appear that all the intervening hollows, plains, and valleys, had been worn away by means of the natural operations of the surface; consequently, that, in a former period of time, there had been a practicable course in a gradual declivity from the Alps to the place where those granite masses are found deposited. In that case, it will be allowed that there are natural means for the transportation of those granite masses from the top of the Alps, by means of water and ice adhering to those masses of stone, at the same time perhaps that there were certain summits of mountains which interrupted this communication, such as the Jura, etc. through the openings of which ridges they had passed.

In this case of blocks of alpine stones upon the Jura, the question is concerning the transportation of those stones; but, in other cases, the question may be how those blocks were formed.

That many such blocks of stone are formed by the decay of the rock around them, is clearly proved by the observations of M. Hassenfratz, published in the _Annales de Chimie_, October 1791. He has particularly mentioned a place on the road from Saint-Flour to Montpellier, where an amazing collection of these blocks of granite is to be seen. It is here particularly that he observes these blocks to be the more durable parts which remain after the rock around them is decayed and washed away. The proof is satisfactory; the operation is important to the present theory; and therefore I shall give it in his own words.

«Tous les blocs de granit dur dégagés et sortis entièrement des masses qui forment les montagnes, posent immédiatement sur le granit friable ou sur d'autres blocs durs qui eux-mêmes sont sur le granit friable.

«Quoique la plupart des blocs de granit dur, que l'on observe sur toute l'étendue de ce terrain granitique, soient entièrement sortis et dégagés de la masse de pierre qui forme la montagne, on en rencontre cependant qui ne sont pas encore tout-à-fait dégagés. Et c'est ici l'observation essentielle qui conduit directement à l'explication du phénomène de l'arrangement, de l'entassement, et de _l'amoncellement_ des blocs d'une manière simple et absolue.

«On voit sur la surface du terrain des portions de blocs durs qui semblent sortir peu à peu, et se dégager de la masse de granit friable; celui-ci se décompose et se réduit en poussière tout autour de cette masse dure que les causes de décomposition du granit friable semblent respecter.

«Quelques-uns de ces blocs durs, sortans de la montagne granitique, sont déjà considérable; on distingue qu'ils n'y tiennent plus que par une très-petite partie; d'autres commencent à paroître se dégager, ils ne _saillent_, ils ne sortent encore que de quelque pieds, et même de quelques pouces. Enfin, en examinant soigneusement et attentivement toute la surface de ce terrain granitique, on apperçoit tous les intermédiaires entre un bloc de granit dur contenu et enchassé dans la masse totale du granit friable et un bloc entièrement dégagé.

«Ces observations, suivies avec attention, ne laissent aucun doute que les blocs de granit que l'on observe sur toute l'étendue de ce terrain granitique, n'aient fait autrefois partie d'une couche considérable de granit décomposable qui couvroit ces montagnes et exhaussoit leur sol; que cette couche, dont il semble impossible d'apprécier la hauteur, malgré les blocs considérable qui restent et qui attestent son existence, a été décomposée par l'air et l'intempérie des saisons; que la poussière, le sable résultans de cette décomposition, ont été entraînés par les eaux, et déposés à divers points de la surface de la globe; et que ces blocs ont été peu-à-peu dégagés de la couche, ainsi qu'il s'en dégage encore tous les jours.»

To enable the reader to form a notion of what these blocks are, I shall farther give what our author has said in describing this place where they are found.

«C'est après avoir quitté le terrain volcanique, c'est dans le terrain granitique que j'ai trouvé des blocs énormes de granit, qui ont fixé mon attention.

«Toute l'étendue du terrain granitique que j'ai traversée, se trouve presque couverte de ces masses; les uns sur les sommets des montagnes les plus élevées, les autres sur la pente et dans les vallées. Plusieurs de ces masses sont arrangées les uns sur les autres avec un art inimitable, les autres sont isolées et éparses.

«Peu de ces masses m'ont présenté un spectacle plus beau et plus imposant que celles que l'on rencontre à 6 heures de marche de S. Flour, à une petite demi heure avant d'arriver à la Garde.

«Là, sur le sommet d'une montagne, est un amas considérable de blocs de granit, étonnans par leur volume et leur nombre. La grande route passe à travers, et circule autour de ces masses que les constructeurs des chemins n'ont pas osé attaquer.

«Le voyageur est pénétré d'admiration en voyant l'ordre et l'arrangement symétrique de ces blocs monstrueux par leur masse, et qu'il ne cesse d'observer en suivant la trace tortueuse du chemin qui les contourne.

«Quelques-uns de ces blocs sont posés purement et simplement les uns sur les autres, et forment une colonne isolée; le plus gros sert de base, et les autres, graduellement plus petits, son posés dessus. On voit jusqu'à trois de ces blocs immédiatement l'un sur l'autre.

«D'autres fois, le bloc qui sert de base est beaucoup plus petit que celui qui le couvre immédiatement; et s'arrangement de ces deux blocs présente l'aspect d'un champignon.

«Plus souvent plusieurs blocs séparés les uns des autres, forment la base, et un ou plusieurs blocs sont posés immédiatement dessus, sans ordre constant, tantôt inclinés, mais toujours d'une manière stable et fixe, propre à resister aux plus grands efforts.

«Enfin, par fois, des masses plus petites placées entre les grosses, semblent assurer la situation fixe de l'ensemble des blocs; mais ces rencontres sont fort rares.»

Here is a distinct view of this part of nature; a view in which the present state of things plainly indicates what has passed, without our being obliged to raise our imagination to so high a pitch as is sometimes required, when we take the mountains themselves, instead of these blocks, as steps of the investigation. Here is a view, therefore, that must convince the most scrupulous, or jealous with regard to the admitting of theory, first, that those mountains had been much higher; secondly, that they had been degraded in their present place; thirdly, that this continent has subsisted in its present place for a very long space of time, during the slow progress of those imperceptible operations; and, lastly, that much of the solid parts of this earth has been thus travelled by the waters to the sea, after serving the purpose of soil upon the surface of the land.

But though M. Hassenfratz has thus given us a most satisfactory view of the natural history of those blocks of stone which are now upon or near their native place, this will not explain other appearances of the same kind, where such blocks are found at great distances from their native places, in situations where the means of their transportation is not to be immediately perceived, such as those resting upon the Jura and Saleve, and where blocks of different kinds of stone are collected together. These last examples are the records of something still more distant in the natural history of this earth; and they give us a more extensive view of those operations by which the surface of this earth is continually changing. It is, however, extremely interesting to this Theory of the Earth, to have so distinctly ascertained some of those first steps by which we are to ascend in taking the more distant prospect; and these observations of M. Hassenfratz answer this end most completely.

Thus all the appearances upon the surface of this earth tend to show that there is no part of that surface to be acknowledged as in its original state, that is to say, the state in which it had come immediately from the mineral operations of the globe; but that, every where, the effects of other operations are to be perceived in the present state of things. The reason of this will be evident, when we consider, that the operations of the mineral kingdom have properly in view to consolidate the loose materials which had been deposited and amassed at the bottom of the sea, as well as to raise above the level of the ocean the solid land thus formed. But the fertility of the earth, for which those operations were performed, and the growth of plants, for which the surface of the earth is widely adapted, require a soil; now the natural, the proper soil for plants, is formed from the destruction of the solid parts. Accordingly, we find the surface of this earth, below the travelled soil, to consist of the hard and solid parts, always broken and imperfect where they are contiguous with the soil; and we find the soil always composed of materials arising from the ruin and destruction of the solid parts.

CHAP. VI.

_A View of the Economy of Nature, and necessity of Wasting the Surface of the Earth, in serving the purposes of this World_.

There is not perhaps one circumstance, in the constitution of this terraqueous globe, more necessary to the present theory, than to see clearly that the solid land must be destroyed, in undergoing the operations which are natural to the surface of the earth, and in serving the purposes which are necessary in the system of this living world. For, all the land of the present earth being a certain composition of materials, perfectly similar to such as would result from the gradual destruction of a continent in the operations of the inhabited world, this composition of our land could not be explained without having recourse to preternatural means, were there not in the constitution of this earth an active cause necessarily, in the course of time, destroying continents.

It is therefore of great importance to this Theory, to show, that the land is naturally wasted, though with the utmost economy; and that the continents of this earth must be in time destroyed. It is of importance to the happiness of man, to find consummate wisdom in the constitution of this earth, by which things are so contrived that nothing is wanting, in the bountiful provision of nature, for the pleasure and propagation of created beings; more particularly of those who live in order to know their happiness, and who know their happiness on purpose to see the bountiful source from whence it flows.

We are to conceive the continent of the earth, when first produced above the surface of the ocean, to be in general consolidated, with regard to its structure, by the same mineral operations which are necessarily employed in raising it from its primary situation at the bottom of the sea, to that in which we now inhabit it.

We are now to consider the purpose of this mineral body, exposed to the influences of the atmosphere, that so we may see the intention of its solid composition, as well as that of its resolution, or natural solubility when thus exposed; and we are to trace the ultimate effects of this order of action in the economy of the globe, that so we may perceive the wisdom of nature perpetuating the system of a living world in an endless succession, of changing perishable forms.

The purpose of the land of this earth, in being placed above the sea and immersed in the atmosphere, is to sustain a system of plants and animals. But; for the purpose of plants; there is required a soil; and, as there is in the vegetable system a vast variety of plants with different habits or natural constitutions, there is also required a diversity of soils, in which those vegetable bodies are to be made to live and prosper. From the bare rock exposed to the sun and wind, to the tender mud immersed in water, there is a series to be observed; and in every stage or step of this gradation, there are plants adapted to those various soils or situations. Therefore nothing short of that diversity of soils and situations, which we find upon the surface of the earth, could fulfill the purpose of nature, in producing a system of vegetables endued with such a diversity of forms and habits.

The soil or surface of this earth is no more properly contrived for the life and sustenance of plants, than are those plants for that diversity of animals, which will thus appear to be the peculiar care of nature in forming a world. Scarce a plant perhaps that has not its peculiar animal which feeds upon its various productions; scarce an animal that has not its peculiar tribe of plants on which the economy of its life, its pleasure, or its prosperity must depend.

If we shall suppose the continent of our earth to be a solid rock, on which the rain might fall, and the wind and waves might dash perpetually, without impairing its mass or changing its constitution, what an imperfect world would we have! how ill adapted to the preservation of animal and vegetable life! But the opposite extreme would equally frustrate the intention of nature, in producing bounteously for the various demands of that multiplicity of species which the author of this world has thought proper to produce.

For if, instead of a solid rock, we shall suppose a continent composed of either dry sand or watery mud, without solidity or stability, how imperfect still would be that world for the purpose of sustaining lofty trees and affording fruitful soils!

We have now mentioned the two extreme states of things; but the constitution of this earth is no other than an indefinite number of soils and situations, placed between those two extremes, and graduating from the one extreme, in which some species of animals and plants delight in finding their prosperity, to the other, in which another species, which would perish in the first, are made to grow luxuriantly. That is to say, the surface of this earth, which is so widely adapted to the purpose of an extensive system of vegetating bodies and breathing animals, must consist of a gradation from solid rock to tender earth, from watery soil to dry situations; all this is requisite, and nothing short of this can fulfil the purpose of that world which we actually see.

We have been representing this continent of our earth as coming out of the ocean a solid mass, which surely it is in general, or in a great degree; but we find the surface of this body at present in a very different state; and now it will be proper to take a view of this change from solid rock to fertile soil.

Upon this occasion I shall give the description of nature from the writings of a philosopher who has particularly studied this subject. It is true that M. de Luc, who furnishes the description, draws, from this process of nature, an argument for the perpetual duration or stability of mountains; and this is the very opposite of that view which I have taken of the subject; but as, in this operation of nature producing plants on stones, he allows the surface of the solid stone to be changed into earth and vegetables, it is indifferent to the present theory how he shall employ this earth and vegetable substance, provided it be acknowledged that there is a change from the solid state of rock to the loose or tender nature of an earth, from the state of a body immovable by the floods and impenetrable to the roots of plants, to one in which some part of the body may be penetrated and removed.

[8]«Les pluies et les rosées forment partout où elles séjournent, des dépôts qui sont la première source de toute _végétation_. Ces dépôts sont toujours mêlés des semences des _mousses_, que l'air charie continuellement, et auxquelles se joignent bientôt les semences presque aussi abondantes des _gramens_, qui sont l'herbe dominante de nos prairies. Ainsi partout où la pluie a formé quelque petit dépôt, il croît de la mousse ou des _gramens_. Ceux-ci demandent un peu plus de _terre végétale_ pour croître, ils germent, et se conservent principalement dans les intervalles et les creux des pierres: mais la _mousse_ croît bientôt sur la surface la plus unie. Il n'est aucune pierre long-temps exposée à l'air, qui soit parfaitement polie; l'action de l'air, du soleil, des eaux, des gelées, detruiroit ce poli quand il existeroit. Le moindre creux alors reçoit un dépôt de la pluie, et nourrit un brin de _mousse,_ ces brins poussent des racines; et de nouveaux jets autour d'eux, qui contribuent à arrêter l'eau de la pluie et de la rosée, et par ce moyen à arrêter les dépôts Nourriciers.»

[Footnote 8: Histoire de la Terre, Tom. 2. page 26.]

«Quand la mousse a multiplié ses filets, les dépôts s'augmentent plus rapidement encore; les brins de la _mousse,_ en séchant et pourrissant, en forment eux-mêmes; car leur substance n'étoit que ces mêmes dépôts façonnés: d'autres semences charriées par l'air, qui au-paravant glissaient sur les pierres, parce que rien ne les retenoit, tombent dans le fond de la _mousse_, et y trouvent l'humidité nécessaire pour produire leurs premières racines: celles-ci s'entrelassent dans la _mousse_, où elles se conservent à l'abri du soleil, et sont alors autant de petites bouches qui pompent les sucs, que l'air, les pluies, et les rosées y déposent. Ces premières plantes sont foibles, quelque fois même elles ne parviennent pas à leur perfection: mais elles ont contribué à fixer la _terre végétable_. En séchant et se décomposant, elles se transforment en cette _terre_, qui tombe au fond de la _mousse_, et qui prépare ainsi de la nourriture pour de nouvelles plantes qui alors prospèrent et fructifient.

«Nous connoissons peu encore ce que c'est que cette _terre végétable_, ce dépôt des pluies ou en général de l'air. Cependant, en rassemblant les phénomènes, on peut conjecturer, que la plupart des corps terrestres sont susceptibles d'être changés en cette substance, et qu'il ne s'agit pour cette transformation que de les décomposer. J'entends par là une telle division de leurs parties, que devenant presque des élémens, elles puissent être intimement mêlées à l'eau, et pompées avec elle par les tuyaux capillaires des plantes. En un mot, il semble suffisant qu'une matière puisse entrer en circulation dans les végétaux, pour qu'elle serve à en développer le tissu, et qu'elle y prenne la figure et les qualités que chacun de ces laboratoires est propres à produire.

«Nous pouvons accélérer de bien des manières la transformation des matières terrestres en _terre végétable_. La fermentation, la calcination, une plus grande exposition à l'air, différens mélanges, rendent propres à la végétation, des matières qui ne l'étoient par elles-mêmes: voila ce que peuvent nos soins. Mais l'air travaille sans cesse et en mille manières. Son simple frottement sur tous les corps, en enlève des particules si atténuées que nous ne les reconnoissons plus. La _poussière_ de nos appartemens en est peut-être un exemple. De quelque nature que soient les corps dont elle se détache, c'est une poudre grisâtre qui semble être partout la même. La formation de la _terre végétable_ a probablement quelque rapport à celle-là. Toute la surface de la terre, les rocs les plus durs, les sables et les graviers les plus arides, les métaux même, éprouvent l'action _rongeante_ de l'air et leurs particules atténuées, décomposées, recomposées de mille manières, sont probablement la source principal de la végétation. _L'air_ lui-même ainsi que _l'eau_, s'y combinent: beaucoup d'observations et d'expériences nous prouvent que ces deux fluides fournissent leur propre substance aux parties solides des végétaux, et par conséquent à la _terre végétable_ qui les produit et qu'ils déposent. Quantité de plantes se nourrissent de _l'eau_ seule, et nous laissant cependant en se séchant, un résidu de matière solide permanente. _L'air_ aussi se _fixe_ dans les corps terrestres, il fait partie de leur substance solide; les chimistes savent de plus en plus, et le _fixer_, et lui redonner son élasticité primitive, par divers procédés: et avant la multitude d'expériences qui se sont de nos jours sur cet objet intéressant de la physique, le Dr. Hales avoit montré, que les végétaux renferment une très-grande quantité _d'air_, qui s'y trouve sans ressort et comme matière constituante.

«Voila donc probablement les sources où la nature puise peu à peu la _terre végétable_ dont elle recouvre la surface de nos continens. Ce sont les particules, peut-être, de tous les corps tant solides que fluides, extraites ou fixées par des procédés qui les rapprochent de leurs premiers élémens, et leur font prendre à nos yeux une même apparence. Ces particules sont ainsi rendues propres à circuler dans les semences des plantes, à en étendre le tissu à y prendre toutes les propriétés qui caractérisent chaque espéce, et à les conserver tant que la plante existe. Ces mêmes particules, après la destruction des plantes, prennent le caractère général de _terre végétable_, c'est-à-dire de provision toute faite pour la végétation.

«Les plus petits recoins des montagnes, qui peuvent arrêter l'eau de la pluie, sont certainement fertilisés; ce ne sont pas seulement les grandes surfaces plates, ni les pentes; ce sont même les faces escarpées des rochers les plus durs. S'il s'y fait quelque crevasse, un arbre s'y établit bientôt; et souvent il contribue, par l'accroissement de ses racines, à accélérer la chute du lambeau de rocher qui l'avoit reçu. S'il y a quelque petite terrasse, ou seulement quelque partie saillante grande comme la main, elle est bientôt gazonnée. Les plus petites sinuosités se peuplent de plantes; et les surfaces les plus unies, celles mêmes qui sont tournées vers la bas, reçoivent au moins quelqu'une de ces _mousses_ plates, nommés _lichen_ par les botanistes, qui ne font en apparence que passer une couleur sur la pierre. Mais cette couche est écaillée, et elle loge bientôt de petites plantes dans ses replis; de celles qui veulent l'ardeur du soleil, si le rocher est au midi, ou la fraîcheur de l'ombre, s'il est au nord: c'est sur ces rochers en un mot, qui paroissent nues aux spectateurs ordinaires, que se trouve la plus grande variété de ces petites plantes, qui font les délices des botanistes, et l'une des sources les plus abondantes où la médicine puise les secours réels qu'elle fournit à l'humanité.

«Quelle richesse dans les ressources de la nature! La pesanteur n'est pas plus prête à entraîner les pierres qui se détachent des montagnes, que l'air à fournir de semences celles qui se fixent: et dès qu'une fois elles sont recouvertes de plantes, elles sont certainement fixées pour toujours, du moins contre les injures de l'air. Le fait même nous l'annonce. Si ces ravins ou ces terreins quelconques, tendoient encore à rouler ou à se dégrader, en un mot à se detruire de quelque manière que ce fut, ils ne le recouvriroient, ni de _mousses_ ni d'aucune autre plante. La première végétation est due à quelque dépôt de _terre végétable_; et les pluies ou l'air n'en forment que lentement; le moindre mouvement la détruite. Le terrein est donc bien certainement fixe quand il se recouvre de plantes; et s'il s'y accumule de la _terre végétable_, c'est un signe bien evident que rien ne l'attaque plus: car elle seroit la première emportée si quelque cause extérieure tendoit a detruire le sol qui la porte.»

The doctrine here laid down by our author consists in this; first, That there is a genus of plants calculated to grow upon rocks or stones; those hard bodies then decay, in decomposing themselves, and affording sustenance to the plants which they sustain. Secondly, That by this dissolution of those rocks, and the accumulation of those vegetable bodies, there is soil prepared for the nurture and propagation of another genus of plants, by which the surface of the earth, naturally barren, is to be fertilised. It is also in this natural progress of things that the solid parts of the globe come to be wasted in the operations of the surface, and that lofty rocks are levelled, in always tending to bring the uneven surface of the earth to a slope of vegetating or fertile soil.

Here we are to distinguish carefully between the facts described by this author, who has seen so much of nature, and the conclusion which he would draw from his principles. The surface of most stones are dissolved, or corroded by the air and moisture. This gives lodgement to the roots of plants, which grow, die, and decay; and these are carried away with the earthy parts of the solid stone, in order to form a vegetable soil for larger plants, growing upon some bottom or resting place to which that earth is carried. Here is so far the purpose of rocks, to sustain a genus of plants which are contrived to live upon that soil; and here is so far a purpose for certain plants, in decomposing rocks to form a soil for other plants which have been made upon a larger scale, and are adapted to the use of man, the ultimate in the view of nature.

Our author concludes thus: (p. 37.) «Le tems ne fera qu'augmenter l'épaisseur de la couche de _terre végétable_ qui couvre les montagnes, et qui les garantit ainsi de plus en plus de cette destruction à laquelle on les croit exposés: les pluies en un mot, au lieu de les dégrader comme on se l'imagine y accumuleront leurs dépôts. Tel est l'agent simple qu'employe si admirablement le Createur pour la conservation de son ouvrage.»

Such, indeed, is the admirable contrivance of the system, that, in the works of nature, nothing shall be destroyed more than is necessary for the preservation of the whole. But, that the whole is preserved by the necessary destruction of every individual body, and the change of every part which comes within the examination of our senses, is sufficiently evident to require no farther illustration in this place, where we are contemplating the destruction of the strongest things, by means the most effectual, though really slow, and apparently most feeble.

In his 30th letter, this author describes the progress of nature, in bringing precipitous rocks to that slope and covering of soil which is to maintain plants of every kind, and to establish woods. (P. 40.) «J'ai l'honneur d'exposer à V.M. les causes qui garantissent de destruction extérieure les terreins sur lesquels la _pesanteur_ ne peut plus agir que pour les consolider. Mais ce n'est pas ainsi que sont actuellement la plupart de nos montagnes; il en est peu qui soyent déjà parvenus à cet état permanent. Tout roc nud est attaqué par l'air et les météores, et il tend à se détruire quelle que soit sa dureté. Mais ce seroit peu que cette destruction extérieure; elle pourroit même cesser enfin totalement par l'effet seul des _mousses_, s'il n'y avoit pas des causes plus puissantes qui pendant quelque tems agissent dans l'intérieur.

«Il n'est presque point de rocher qui offre à l'air une seule masse compacte; ils sont ou crevassés, ou formés par couches; et l'eau s'insinue toujours dans ces fentes. Quand cette eau vient à se geler, elle agit comme un coin pour écarter les pièces entre lesquelles elle se trouve. V.M. seroit étonnée de la grandeur des masses que cette cause peut mouvoir: elle agit exactement comme la poudre à canon dans les mines; détachant toutes les pièces extérieures qui commencent à se séparer, et en découvrant ainsi de nouvelles. Chaque hiver renouvelle donc la surface de certains rochers, ou facilite l'ouvrage pour les hivers suivans.

Plusieurs autres causes agissent encore pour séparer les rochers déjà crevassés, qui se trouvent à l'extérieur des faces escarpées. Le petit moellon qui s'y accumule, les dépôts des pluies, les plantes qui y croissent, les alternatives de l'humidité et de la sécheresse, les vicissitudes de la chaleur, les vents même, sont autant de causes continuellement agissantes quand la _pesanteur_ les seconde. Les rochers escarpés se détruisent donc par de continuels éboulemens.

«Mais toutes ces matières qui tombent, ne sont pas perdues pour les montagnes; il s'en perd même bien peu. Elles s'arrêtent au pied des rochers dont elles sont successivement détachées; et là elles s'entassent, s'élevant en forme de _talus_ contre ces rochers eux-mêmes.»

If the solid body of the Alps, the most consolidated masses of our land, is thus reduced to the state of soil upon the surface of the earth contrived for the use of plants, _a fortiori_, softer bodies, less elevated and less consolidated masses, will be considered as easily arriving at the purpose for which the surface of the earth has been intended. We only wish now to see the ultimate effect that necessarily follows from this progress of things; and how, in this course of nature, the land must end, however long protracted shall be the duration of this body, and however much economy may be perceived in this gradual waste of land;--a waste which by no means is so slow as not to be perceived by men reasoning in science; although scientific men, either reasoning for the purpose of a system which they had devised, or, deceived by the apparent state of things which truly change, may not acknowledge the necessary consequence of what they had perceived.

Let us now suppose all the solid mass of land, contained in our continent, to be transformed into soil and vegetable earth, it must be evident that no covering of plants, or interlacing of vegetable fibres, could protect this mass of loose or incoherent materials from the ravages of floods, so long as rivers flowed, nor from being swallowed by the ocean, so long as there were winds and tides. From the border of the land upon the shore, to the middle of the ocean, there is either at present an equable declivity at the bottom of the sea, or every thing tends to form this declivity, in gradually moving bodies along this bottom. But, however gradual the declivity of the bottom, or however slow the progress of loose materials from the shore towards the deepest bottom of the sea, so long as there are moving powers for those materials, they must have a progress to that end; the law of gravitation, always active, must prevail, and sooner or later the moving sea must swallow up the land.

But, along the borders of our continent, and in the courses of our rivers, there are rocks; these must be surmounted or destroyed, before the parts which they protect can be delivered up to the influence of those moving powers which tend to form a level; and we may be assured that those bulwarks waste. The bare inspection of our rocky coasts and rivers will satisfy the enlightened observator of this truth; and to endeavour to prove this to a person who has not principles by which to reason upon the subject, or to one who has false principles, by which he would create perpetual stability to decaying things, would be but labour lost.

In proportion as the solid bulwark is destroyed, so is the soil which had been protected by it; and, in proportion as the solid parts of the mass of land are exposed to the influences of the atmosphere and water, by the ablution of the soil, more soil is prepared for the growth of plants, and more earth is detached from the solid rock, to form deep soils upon the surface of the earth, and to establish fertile countries at the mouths of rivers, even in making encroachment on the space allotted for the sea. But this production of land, in augmentation of our coasts, is only made by the destruction of the higher country. While, therefore, we allow that there is any augmentation made to the coast, or any earthy matter travelling in our rivers, the land above the coast cannot be stable, nor the constitution of our earth fixed in a state which has no tendency to be removed.

M. de Luc, in his Histoire de la Terre, would make the mountains last for ever, after they have come to a certain slope. He sums up his reasoning upon this subject in these words: «L'adoucissement des pentes arrête d'abord l'effet de ces deux grandes causes causes de destruction de montagnes, la _pesanteur_ et les _eaux_: la végétation ensuite arrêté l'effet de toutes les petites cause.»