Theory of the Earth Volume I Part 14

It must not be alleged, that the heights of the Oural mountains, or the hardness of their rocks, make an essential distinction between them and the argillaceous or arenaceous strata of the plains; solidity and hardness, as well as changes in their height and natural position, has been superinduced in operations posterior to the collection of those ma.s.ses,--operations which may be formed in various degrees, even in the different parts of the same ma.s.s. If this is the case, there can be no difficulty in conceiving a stratum, which appears to be argillaceous or marly in the plains, to be found jasper in the Oural mountains. But there is nothing in the Oural mountains, that may not be found some where or other in the plains, although the soft and easily decomposing argillaceous strata be not found upon the Oural mountains, or the Alps, for this reason, that had those mountains been formed of such materials, there had not been a mountain there at this day.

But surely the greatest possible error, with regard to the philosophy of this earth, would be to confound the sediment of a river with the strata of the globe; bodies deposited upon the surface of the earth, with those sunk at the bottom of the sea; and things which only form the travelled or transported soil, with those which const.i.tute the substratum or the solid earth. How far M. Pallas has committed this oversight, I leave others to determine. After mentioning those strata in which wood is found petrified, and metallic minerals formed, he thus proceeds, (page 69).

"Dans ces memes depots sableux et souvent limoneux, gisent les restes des grands animaux de l'Inde: ces oss.e.m.e.ns d'elephans, de rhinoceros, de buffles monstrueux, dont on deterre tous les jours un si grand nombre, et qui font l'admiration des curieux. En Siberie, ou l'on a decouvert le long de presque toutes les rivieres ces restes d'animaux etrangers, et l'ivoire meme bien conserve en si grande abondance, qu'il forme un article de commerce, en Siberie, dis je, c'est aussi la couche la plus moderne de limon sablonneux qui leur sert de sepulture, et nulle part ces monumens etrangers sont si frequens, qu'aux endroits ou la grande chaine, qui domine surtout la frontiere meridionale de la Siberie, offre quelque depression, quelque ouverture considerable.

"Ces grands oss.e.m.e.ns, tantot epars tantot enta.s.ses par squelettes, et meme par hecatombes, consideree dans leurs sites naturels, m'ont sur-tout convaincu de la realite d'un deluge arrive sur notre terre, d'une catastrophe, dont j'avoue n'avoir pu concevoir la vraisemblance avant d'avoir parcouru ces places, et vu, par moi-meme, tout ce qui peut y servir de preuve a cet evenement memorable[24]. Une infinite de ces oss.e.m.e.ns couches dans des lits meles de pet.i.tes tellines calcinees, d'os de poissons, de glossopetres, de bois charges d'ocre, etc. prouve deja qu'ils ont ete transportes par des inondations. Mais la carca.s.se d'un rhinoceros, trouve avec sa peau entiere, des restes de tendons, de ligamens, et de cartilages, dans les terres glacees des bords du Viloui, dont j'ai depose les parties les mieux conservees au cabinet de l'Academie, forme encore une preuve convaincante que ce devait etre un mouvement d'inondation des plus violens et des plus rapides, qui entraina jadis ces cadavres vers nos climats glaces, avant que la corruption eut le tems, d'en detruire les parties molles. Il seroit a souhaiter qu'un observateur parvint aux montagnes qui occupent l'es.p.a.ce entre les fleuves Indighirka et Koylma ou selon le rapport des cha.s.seurs, de semblables carca.s.ses d'elephans et d'autres animaux gigantesques encore revetues de leurs peaux, ont ete remarquees a plusieurs reprises."

[Note 24: Voyez le Memoire, imprime dans le XVII. volume des nouveaux Commentaires de l'Academie Imperiale de Petersbourgh.]

The question here turns upon this, Are the sea sh.e.l.ls and glossopetrae, which are thus found deposited along with those skeletons, in their natural state, or are they petrified and mineralised. If the productions of the sea shall here be found collected along with bodies belonging to the surface of the earth, and which had never been within the limits of the sea, this would surely announce to us some strange catastrophe, of which it would be difficult, perhaps, to form a notion; if, on the contrary, those marine productions belong to the solid strata of the earth, in the resolution or decay of which they had been set at liberty, and were transported in the floods, our author would have no reason from those appearances to conclude, there had existed any other deluge than those produced by the waters of the land[25].

[Note 25: Since writing this, I find my doubts in a great measure resolved, in reading M. Pallas's Journal, translated from the German by M. Gauthier de la Peyronie. What I had suspected is, I think, confirmed in the distinct account which M. Pallas has given of those occasions in which the bones of land animals and marine objects are found buried together. The marine objects are mineralised; consequently, they have proceeded from the decomposition of the solid strata; and, having been travelled in the running water of the surface of the earth, they must have been deposited in those beds of rivers, which now are dry, alongst with the bones, or the entire bodies of terrestrial animals, the remains of which are now found there. This argument, from the state of those marine bodies will not be allowed, perhaps by the generality of mineralists, who attribute to the operations of water every species of petrifaction or mineralisation; but, until some species of proof be given with regard to the truth of that theory, which vulgar error first suggested, I must reason from a theory, in proof of which I have given clear examples, and, I think, irrefragable arguments, which shall be more and more ill.u.s.trated. Thus may be removed the necessity of a general deluge, or any great catastrophe, in order to bring together things so foreign to each other; but at the same time we would ascertain this fact, That formerly the Elephant and Rhinoceros had lived in Siberia. (See Voyage de Pallas, Tom. II. p. 377 and 403.)]

Having thus endeavoured to remove this prevailing prejudice, of there being primitive parts in this earth, parts of which the composition and const.i.tution are not to be explained upon the principles of natural philosophy, it will be proper to inquire, how far there may be in the theory, which has now been given, principles by which may be explained those appearances that have led natural philosophers to form conclusions, of there being in this earth parts whose origin may not be traced; and of there being parts whose origin may not be explained upon the same principles which apply so well to all the rest.

CHAP. V.

Concerning that which may be termed the Primary Part of the Present Earth.

In the present theory, it is maintained, that there is no part of the earth which has not had the same origin, so far as this consists in that earth being collected at the bottom of the sea, and afterwards produced, as land, along with ma.s.ses of melted substances, by the operation of mineral causes. But, though all those things be similar, or equal, as to the manner of their production, they are far from being so with regard to the periods of their original composition, or to the subsequent operations which they may have undergone.

There is a certain order established for the progress of nature, for the succession of things, and for the circulation of matter upon the surface of this globe; and, the order of time is a.s.sociated with this change of things. But it is not in equal portions that time is thus combined with dissimilar things, nor always found, in our estimation, as equally accompanying those which we reckon similar. The succession of light and darkness is that which, in those operations, appears to us most steady; the alternation of heat and cold comes next, but not with equal regularity in its periods. The succession of wet and dry upon the surface of the earth, though equally the work of nature and the effect of regular causes, is often to us irregular, when we look for equal periods in the course of things which are unequal. It is by equalities that we find order in things, and we wish to find order every where.

The present object of our contemplation is the alternation of land and water upon the surface of this globe. It is only in knowing this succession of things, that natural appearances can be explained; and it is only from the examination of those appearances, that any certain knowledge of this operation is to be obtained. But how shall we acquire the knowledge of a system calculated for millions, not of years only, nor of the ages of man, but of the races of men, and the successions of empires? There is no question here with regard to the memory of man, of any human record, which continues the memory of man from age to age; we must read the transactions of time past, in the present state of natural bodies; and, for the reading of this character, we have nothing but the laws of nature, established in the science of man by his inductive reasoning.

It has been in reasoning after this manner, that I have endeavoured to prove, that every thing which we now behold, of the solid parts of this earth, had been formerly at the bottom of the sea; and that there is, in the const.i.tution of this globe, a power for interchanging sea and land.

If this shall be admitted as a just view of the system of this globe, we may next examine, how far there are to be found any marks of certain parts of our earth having more than once undergone that change of posture, or vicissitude of things, and of having had reiterated operations of the mineral kingdom changing their substance, as well as altering their positions in relation to the atmosphere and sea.

Besides the gradual decay of solid land, exposed to the silent influences of the atmosphere, and to the violent operations of the waters moving upon the surface of the earth, there is a more sudden destruction that may be supposed to happen sometimes to our continents of land. In order to see this, it must be considered, that the continents of our earth are only raised above the level of the sea by the expansion of matter, placed below that land, and rarified in that place: We may thus consider our land as placed upon pillars, which may break, and thus restore the ancient situation of things when this land had been originally collected at the bottom of the ocean. It is not here inquired by what mechanism this operation is to be performed; it is certainly by the exertion of a subterranean power that the land is elevated from the place in which it had been formed; and nothing is more natural than to suppose the supports of the land in time to fail, or be destroyed in the course of mineral operations which are to us unknown.

In that case, whatever were remaining of that land, which had for millions of ages past sustained plants and animals, would again be placed at the bottom of the sea; and strata of every different species might be deposited again upon that ma.s.s, which, from an atmospheric situation, is now supposed to be lower than the surface of the sea.

Such a compound ma.s.s might be again resuscitated, or restored with the new superinc.u.mbent strata, consolidated in their texture and inclined in their position. In that case, the inferior ma.s.s must have undergone a double course of mineral changes and displacement; consequently, the effect of subterranean heat or fusion must be more apparent in this ma.s.s, and the marks of its original formation more and more obliterated.

If, in examining our land, we shall find a ma.s.s of matter which had been evidently formed originally in the ordinary manner of stratification, but which is now extremely distorted in its structure, and displaced in its position,--which is also extremely consolidated in its ma.s.s, and variously changed in its composition,--which therefore has the marks of its original or marine composition extremely obliterated, and many subsequent veins of melted mineral matter interjected; we should then reason to suppose that here were ma.s.ses of matter which, though not different in their origin from those that are gradually deposited at the bottom of the ocean, have been more acted upon by subterranean heat and the expanding power, that is to say, have been changed in a greater degree by the operations of the mineral region. If this conclusion shall be thought reasonable, then here is an explanation of all the peculiar appearances of the alpine schistus ma.s.ses of our land, those parts which have been erroneously considered as primitive in the const.i.tution of the earth.

We are thus led to suppose, that some parts of our earth may have undergone the vicissitudes of sea and land more than once, having been changed from the summit of a continent to the bottom of the sea, and again erected, with the rest of that bottom, into the place of land. In that case, appearances might be found to induce natural philosophers to conclude that there were in our land primary parts, which had not the marine origin which is generally to be acknowledged in the structure of this earth; and, by finding other ma.s.ses, of marine origin, superinc.u.mbent upon those primary mountains, they might make strange suppositions in order to explain those natural appearances.

Let us now see what has been advanced by those philosophers who, though they term these parts of the earth _primordial_, and not _primitive_, at the same time appear to deny to those parts an origin a.n.a.logous to that of their secondary mountains, or strata that are aquiform in their construction.

M. de Luc, after having long believed that the strata of the Alps had been formed like those of the low countries, at the bottom of the sea, gives an account of the occasion by which he was first confirmed in the opposite opinion.[26] Like a true philosopher, he gives us the reason of this change.

[Note 26: Lettres Physique et Morales sur l'Histoire de la Terre, tom.

2. pag. 206.]

"Ce fut une espece de _montagne_ tres commune, et que j'avois souvent examinee qui dessilla mes yeux. La pierre qui la compose est de la cla.s.se appellee _schiste_; son caractere generique est d'etre _feuilletee_; elle renferme _l'ardoise_ dont on couvre les toits. Ces _feuillets_ minces, qu'on peut prendre pour des _couches_, et qui le font en effet dans quelques pierres de ce genre, rappelloient toujours l'idee vague de depots des eaux. Mais il y a des ma.s.ses dont la composition est plutot par fibres que par feuillets, et dont le moellon ressemble aux copeaux de bois d'un chantier. Le plus souvent aussi les feuillets sont situes en toute suite de sens dans une meme _montagne_, et quelquefois meme verticalement, Enfin il s'en trouve de si tortilles, qu'il est impossible de les regarder comme des depots de l'eau.

"Ce fut donc cette espece de montagne qui me persuada la premiere que toutes les montagnes n'avoient pas une meme origine. Le lieu ou j'abjurai mon erreur, etoit un de ces grands _chantiers_ petrifies, qui, par la variete du tortillement, et des zig-zags des fibres du moellon qui le composoit, attira singulierement mon attention. C'etoit un sort grand talus qui venoit d'une face escarpee; j'y montai pour m'approcher du rocher, et je remarquai, avec etonnement, des mult.i.tudes de paquets enchevetres les uns dans les autres, sans ordre ni direction fixe; les uns presqu'en rouleaux; les autres en zig-zag; et meme ce qui, separe de la montagne, eut peu etre pris pour des _couches_, le trouvoit incline de toute maniere dans cette meme face de rocher. _Non_, me dis-je alors a moi-meme; _non, l'eau n'a pu faire cette montagne.... Ni celle-la donc_, ajoutai-je en regardant ailleurs.... _Et pourquoi mieux celle-la?

Pourquoi toutes les montagnes devroient-elles etre le produit des eaux, seulement parce qu'il y en a quelques-unes qui annoncent cette origine_?

En effet, puis qu'on n'a songe aux eaux, comme cause des montagnes, que par les preuves evidentes que quelques-unes offroient de cette formation; pourquoi etendre cette consequence a toutes, s'il y en a beaucoup qui manquent de ces caracteres? C'est comme le dit Mr.

d'Alembert, qu'on generalise ses premieres remarques l'instant d'apres qu'on ne remarquoit rien."

Science is indebted to this author for giving us so clear a picture of natural appearances, and of his own reasoning upon those facts, in forming his opinion; he thus leads astray no person of sound judgment, although he may be in error. The disposition of things in the present case are such, that, reasoning from his principles, this author could not see the truth; because he had not been persuaded, that aquiform strata could have been so changed by the chemical power of fusion, and the mechanical force of bending while in a certain state of softness.

But though, in this case, the reasoning of this philosopher is to be justified, so far as he proceeded upon principles which could not lead him to the truth, his conduct is not so irreproachable in applying them to cases by which their fallacy might have been detected. This author acknowledges calcareous strata to be aquiform in their original; but, in those mountains which he has so much examined, he will find those aquiform bodies have undergone the same species of changes, which made him conclude that those schistus mountains had not been truly aquiform, as he at first had thought them. This would have led him to reason back upon his principles, and to say, _If one species of strata may be thus changed in its texture, and its shape, may not another be equally so?

Therefore, may not the origin of both be similar_?

But least I should do injustice to this author, to whom we are indebted for many valuable observations in natural history, I shall transcribe what he has said upon the subject, being persuaded that my readers will not think this improper in me, or impertinent to the argument.

"Quand nous fumes une fois persuades que la mer n'avoit pas fait toutes les _montagnes_, nous entreprimes de decouvrir les caracteres distinctifs de celles qui lui devoient leur origine; et s'il etoit, par exemple, des matieres qui leur fussent propres. Mais nous y trouvames les memes difficultes qu'on rencontre dans tout ce qu'on veut cla.s.ser dans la nature. On peut bien distinguer entr'elles les choses qui ont fortement l'empreinte de leur cla.s.se; mais les confins echappent toujours.

"C'est la, pour le dire en pa.s.sant, ce qui a pu conduire quelques philosophes a imaginer cette _chaine des etres_ ou ils supposent, que, de la pierre a l'homme et plus haut, les nuances sont reellement imperceptibles. Comme si, quoique les limites soyent cachees a nos sens, notre intelligence ne nous disoit pas, qu'il y a un _saut_, une distance meme infinie, entre le plus pet.i.t degre d'organization _propageante_, et la matiere unie par la simple cohesion: entre le plus pet.i.t degre de _sensibilite_, et la matiere insensible: entre la plus pet.i.te capacite d'observer et de transmettre ses observations, et l'instinct constamment le meme dans l'espece. Toutes ces differences tranchees existent dans la nature; mais notre incapacite de rien connoitre a fond, et la necessite ou nous sommes de juger de tout sur des apparences, nous fait perdre presque toutes les limites, parce que sur ces bords, la plupart des phenomenes sont equivoques. Ainsi la plante nous paroit se rapprocher de la pierre, mais n'en approche jamais reellement.

"On eprouve la meme difficulte a cla.s.ser les montagnes; et quoique depuis quelque tems plusieurs naturalistes ayent aussi observe qu'elles n'ont pas toutes la meme origine, je ne vois pas qu'on soit parvenu a fixer des caracteres infaillibles, pour les placer surement toutes dans leurs cla.s.ses particulieres.

"Apres avoir examine attentivement cet objet, d'apres les phenomenes que j'ai moi-meme observes, et ce que j'ai appris par les observations des autres; j'ai vu que c'etoit la un champ tres vaste, quand on vouloit l'embra.s.ser en entier, et trop vaste pour moi, qui n'etoit pas libre d'y consacrer tout le tems qu'il exige. Je me suis donc replie sur mon objet princ.i.p.al, savoir _la cause qui a laisse des depouilles marines dans nos continens_, et l'examen des hypotheses sur cette matiere.

"Les phenomenes ainsi limites, se reduisent a ceci: qu'il y a dans nos continens des montagnes visiblement formees par des _depots successifs de la mer_ et a l'egard des quelles il n'y a besoin de rien imaginer, si ce n'est la maniere dont elles en sont sorties: qu'il y en a d'autres au contraire, qui ne portent aucun des caracteres de cette cause, et qui, si elles ont ete produites dans la _mer_, doivent etre l'effet de toute autre cause que de simples depots successifs, et avoir meme precede l'existence des animaux marins. J'abandonne donc les cla.s.ses confuses ou ces caracteres sont equivoques, jusqu'a ce qu'elles servent a fonder quelque hypothese; ayant a.s.sez de ces deux cla.s.ses tres distinctes pour examiner d'apres elles tous les systemes qui me sont connus.

"La ou ces deux cla.s.ses de montagnes sont melees, on remarque que celles qui sont formees par _couches_, et qui renferment des _corps marins_, recouvrent souvent celles de l'autre cla.s.se, mais n'en sont jamais recouvertes. On a donc naturellement conclu, que lors meme que la _mer_ auroit en quelque part a la formation des montagnes ou l'on ne reconnoit pas son caractere, celles auxquelles elle a travaille seule, en enlevant des matieres dans certaines parties de son fond et les deposant dans d'autres, font au moins les dernieres formees. On les a donc nommees _secondaires_, et les autres _primitives_.

"J'adopterai la premiere de ces expressions; car c'est la meme qui nous etoit venu a l'esprit a mon frere, et a moi longtemps avant que nous l'eussions vue employer; mais je subst.i.tuerai celle de _primordiales a_ _primitives_ pour l'autre cla.s.se de _montagnes_, afin de ne rien decider sur leur origine. Il est des _montagnes_, dont jusqu'a present on n'a pu demeler la cause: voila le fait. Je ne dirai donc pas qu'elles ont ete creees ainsi, parce qu'en physique je ne dois pas employer des expressions sur lesquelles on ne s'entend pas. Sans doute cependant, que l'histoire naturelle ni la physique ne nous conduisent nullement a croire que notre globe ait existe de toute eternite; et lorsqu'il prit naissance, il fallut bien que la matiere qui le composa fut de quelque nature, ou sous quelque premiere forme integrante. Rien donc jusqu'ici n'empeche d'admettre que ces _montagnes_ que je nommerai _primordiales_, ne soient reellement _primitives_; je penche meme pour cette opinion a l'egard de quelques unes. Mais il y a une tres grande variete entr'elles; et quoiqu'elles soyent toutes egalement exclues de la cla.s.se _secondaire_, elles ne sont pas toutes semblables: il y en a meme un grand nombre dont les matieres ont une certaine configuration qui semble annoncer qu'elles ayent ete molles et durcies ensuite, quoique par une toute autre cause que celle qui a agi pour former les montagnes secondaires."

Here I would beg leave to call the attention of philosophers to this observation of a naturalist who explains all petrification, and the consolidation of strata by aqueous infiltration. If he has here found reason to conclude that, in those primordial parts of the earth, there are a great number which, from their present configuration, must have been in a soft state and then hardened, and this by a quite different cause from that which he supposes had produced the consolidation and hardness of the secondary parts; this is entering precisely into my views of the subject, in ascribing all the consolidation of the earth, whether primary or secondary, to one general cause, and in tracing this cause, from its effects, to be no other than the fusion of those bodies.

It must be evident, that if this philosopher has seen good reason for concluding such a softening cause, which had operated upon the primary parts, to be quite different from that which he ascribes to the consolidation of the secondary, which is the effect of water, it must then, I say, be evident that the softening cause of the primary parts, if not heat, by which every degree of fusion may be produced, must be an occult cause, one which cannot be admitted into natural philosophy.

By thus choosing to consider mountains as of two distinct kinds, one aquiform which is understood, and the other primordial which is not to be known, we supersede the necessity of reconciling a theory with many appearances in nature which otherwise might be extremely inconvenient to our explanation, if not inconsistent with our system. Our author no doubt has thus relieved himself from a considerable difficulty in the philosophy of this earth, by saying here is a great part which is not to be explained. But I would beg leave to observe, that this form of discussion, with regard to a physical subject, is but a mere confession of our ignorance, and has no tendency to clear up another part of the subject of which one treats, however it may impress us with a favourable opinion of the theorist, in allowing him all the candour of the acknowledgement.

The general result of the reasoning which we now have quoted, and what follows in his examination, seems to terminate in this; that there are various different compositions of mountains which this author cannot allow to be the production of the sea; but it is not upon account of the matter of which they are formed, or of the particular mixture and composition of those species of matter, of which the variety is almost indefinite. According to this philosopher, the distinction that we are to make of those primordial and secondary compet.i.tions, consists in this, that the first are in such a shape and structure as cannot be conceived to be formed by subsidence in water.

M. de Saussure has carefully examined those same objects; and he seems inclined to think that they must have been the operation of the ocean; not in the common manner of depositing strata, but in some other way by crystallization. The present theory supposes all those ma.s.ses formed originally in the ordinary manner, by the deposits or subsidence of materials transported in the waters, and that those strata were afterwards changed by operations proper to the mineral regions.

But the subject of the present investigation goes farther, by inquiring if, in the operations of the globe, a primary and secondary cla.s.s of bodies may be distinguished, so far as the one may have undergone the operations of the globe, or the vicissitudes of sea and land, oftener than the other, consequently must be anterior to the later productions both in time and operation, although the original of all those bodies be the same, and the operations of the earth, so far as we see in the effects, always proceed upon the same principles. This is an extensive view of nature to which few have turned their thoughts. But this is a subject to which the observations described by this author have evidently a reference.

In his 113th letter, he has given us a view of one of those parts of the earth that are proper to be examined in determining this question so important in the genealogy of land, although no ways concerned in altering the principles upon which nature in forming continents must proceed.

It is in describing the nature of the mountains about _Elbingerode_; and he begins in ascending from Hefeld.

"Cette partie exterieure de la chaine est _primordiale_: c'est du _granit_ a _Hereld_ et au commencement de la route; puis quand on pa.s.se dans d'autres vallees, on trouve les _schistes_ et la _roche grise_ dans tout le pied des montagnes: mais des qu'on est arrive a une certain hauteur, on voit de la _pierre a chaux_ par couches etendue sur ces matieres; et c'est elle qui forme le sommet de ces memes montagnes; tellement que la plaine elevee, qui conduit a _Elbingerode_, est entierement de _pierre a chaux_, excepte dans sa partie la plus haute ou cette pierre est recouverte des memes _gres_ et sables _vitrescibles_ qui sont sur le schiste du Bruchberg et sur la _pierre a chaux_ dans la _Hesse_ et le pays de Gottingue.

"Les environs d'Elbingerode etant plus bas que ces parties recouvertes de matieres vitrescibles, montrent la _pierre a chaux_ a nud; et l'on y trouve de tres beaux marbres, dont les nuances jaunes, rouges et vertes sont souvent tres vives, et embellies par les coupes des _corps marins_.

"Cependant le schiste n'est pas enseveli partout sous ces depots de la mer; on le retrouve en quelques endroits, et meme avec de _filons_.

"Ainsi au milieu de ces matieres _calcaires_ qui forment le sol montueux des environs _d'Elbingerode_, paroit encore le _schiste_ sur lequel elles ont ete deposees: Et en montant a la partie la plus elevee de ces memes environs, on trouve que la _pierre a chaux_ est recouverte elle-meme d'une _pierre sableuse_ grise par couches, dans laquelle on voit quant.i.te de pet.i.ts fragmens de _schiste_ poses de plat. C'est la que se trouve une des mines de _fer_ dont le minerai va en partie a la _Koningshutte_, mais en plus grande partie a la _Rothechutte_, qui n'est qu'a une lieue de distance. On perce d'abord la couche sableuse; sous elle se trouve de la _pierre a chaux_ grise; puis une couche de _pierre a chaux ferrugineuse_, remplie de _corps marins_, et surtout _d'entroques_: C'est cette _couche_ qui est ici le _minerai_; et elle appartient a la formation de cette eminence comme toutes les autres _couches_. Cette mine se nomme _bomshey_: elle n'est pas riche; mais elle sert de _fondant_ aux matieres ferrugineuses tirees des filons des montagnes primordiales en meme tems qu'elle leur ajoute son _fer_ dans la fonte. A quelque distance de la on a perce un autre puits; qui a transverse d'abord une sorte de pierre, que je ne saurois nommer, mais qui ressemble fort a une _lave_ poreuse. Au dessous de cette couche on a retrouve la _pierre a chaux_ ordinaire; puis la _couche ferrugineuse_ y continue; mais elle differe un peu de ce qu'elle est dans l'autre mine, une partie de sa substance etant convertie en _jaspe_.

"Mais ce qui est digne de la plus grande attention dans cette contree, est un filon peu distant nomme _Buchenberg_, qui appartient en partie au Roi, et en partie a Mr. le Comte de _Wernigerode_. La montagne en cette endroit montre une vallee artificielle de 70 a 80 pieds de profondeur, de 20 a 30 de largeur dans le haut, et de 400 toises en etendue. C'est le creus.e.m.e.nt qu'on a deja fait en suivant ce _filon_ de _fer_, que l'on continue a exploiter de la meme maniere sur les terres de Mr. le Comte de _Wernigerode_. La matiere propre de la montagne _est_ de _schiste_; et la vallee qui se forme de nouveau a mesure qu'on enleve la _gangue_ du _filon_, a surement deja existe dans la mer sous la forme d'une _fente_, qui a ete remplie, et en particulier des ingrediens dont on fait aujourd'hui le _fer_."