Chapter II (5)

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 competitions, 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 masses 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 class 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 extérieure de la chaîne est _primordiale_: c'est du _granit_ à _Hereld_ et au commencement de la route; puis quand on passe dans d'autres vallées, on trouve les _schistes_ et la _roche grise_ dans tout le pied des montagnes: mais des qu'on est arrivé à une certain hauteur, on voit de la _pierre à chaux_ par couches étendue sur ces matières; et c'est elle qui forme le sommet de ces mêmes montagnes; tellement que la plaine élevée, qui conduit à _Elbingerode_, est entièrement de _pierre à chaux_, excepté dans sa partie la plus haute ou cette pierre est recouverte des mêmes _grès_ et sables _vitrescibles_ qui sont sur le schiste du Bruchberg et sur la _pierre à chaux_ dans la _Hesse_ et le pays de Gottingue.

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

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

"Ainsi au milieu de ces matières _calcaires_ qui forment le sol montueux des environs _d'Elbingerode_, paroît encore le _schiste_ sur lequel elles ont été déposées: Et en montant à la partie la plus élevée de ces mêmes environs, on trouve que la _pierre à chaux_ est recouverte elle-même d'une _pierre sableuse_ grise par couches, dans laquelle on voit quantité de petits fragmens de _schiste_ posés de plat. C'est la que se trouve une des mines de _fer_ dont le minerai va en partie à la _Koningshutte_, mais en plus grande partie à la _Rothechutte_, qui n'est qu'à une lieue de distance. On perce d'abord la couche sableuse; sous elle se trouve de la _pierre à chaux_ grise; puis une couche de _pierre à chaux ferrugineuse_, remplie de _corps marins_, et surtout _d'entroques_: C'est cette _couche_ qui est ici le _minerai_; et elle appartient à la formation de cette éminence comme toutes les autres _couches_. Cette mine se nomme _bomshey_: elle n'est pas riche; mais elle sert de _fondant_ aux matières ferrugineuses tirées des filons des montagnes primordiales en même tems qu'elle leur ajoute son _fer_ dans la fonte. A quelque distance de là on a percé un autre puits; qui a transversé d'abord une sorte de pierre, que je ne saurois nommer, mais qui ressemble fort à une _lave_ poreuse. Au dessous de cette couche on a retrouvé la _pierre à chaux_ ordinaire; puis la _couche ferrugineuse_ y continue; mais elle diffère un peu de ce qu'elle est dans l'autre mine, une partie de sa substance étant convertie en _jaspe_.

"Mais ce qui est digne de la plus grande attention dans cette contrée, est un filon peu distant nomme _Buchenberg_, qui appartient en partie au Roi, et en partie à Mr. le Comte de _Wernigerode_. La montagne en cette endroit montre une vallée artificielle de 70 à 80 pieds de profondeur, de 20 à 30 de largeur dans le haut, et de 400 toises en étendue. C'est le creusement qu'on a déjà fait en suivant ce _filon_ de _fer_, que l'on continue à exploiter de la même manière sur les terres de Mr. le Comte de _Wernigerode_. La matière propre de la montagne _est_ de _schiste_; et la vallée qui se forme de nouveau à mesure qu'on enlève la _gangue_ du _filon_, a sûrement déjà existé dans la mer sous la forme d'une _fente_, qui a été remplie, et en particulier des ingrédiens dont on fait aujourd'hui le _fer_."

Here is a supposition of our author that corresponds to nothing which has yet been observed any where else, so far as I know. It is concerning a mineral vein, one which does not appear to differ in any respect from other mineral veins, except in being worked in that open manner which has given our author an idea of its being a valley. He then supposes that valley (or rather empty vein) to have been in this mountain when at the bottom of the sea, and that this mineral vein had then been filled with those materials which now are found in that space between the two sides of the separated rock. This is a very different operation from that of infiltration, which is commonly supposed to be the method of filling mineral veins; but, we shall soon see the reason why our author has here deserted the common hypothesis, and has adopted another to serve the occasion, without appearing to have considered how perfectly inconsistent those two suppositions are to each other. That mineral veins have been filled with matter in a fluid state, is acknowledged by every body who has either looked at a mineral vein in the earth, or in a cabinet specimen; mineralists and geologists, in general, suppose this to have been done by means of solutions and concretions, a supposition by no means warranted by appearances, which, on the contrary, in general demonstrate that the materials of those veins had been introduced in the fluid state of fusion. But here is a new idea with regard to the filling of those veins; and, I would now beg the reader's attention to the facts which follow in this interesting description, and which have suggested that idea to our author.

"Quand cette matière accidentelle est enlevée, on voit la coupe du _schiste_ des deux côtes de la _fente_, faisant un _toit_ et un _mur_, parce que la _fente_ n'est pas absolument verticale: des qu'il y a un peu d'inclinaison, on distingue un _toit_ et un mur, comme j'ai l'honneur de l'expliquer à V.M. On ne connoît point encore l'étendue de ce filon, ni dans sa profondeur, où l'on ne peut pas s'enfoncer beaucoup de cette manière, ni dans la longueur, selon laquelle on continue à l'exploiter.

"Voilà donc un _filon_, à la rigueur de la définition que j'en ai donné à V.M. c'est à dire, une _fente_ dans la montagne naturelle, _comblée_ de _matière_ étrangère. Mais ce qu'il y a d'extraordinaire ici, c'est que cette _matière_ vient de la _mer_: ce sont différentes _couches aquiformes_, dont quelques unes sont remplies de _corps marins_. Il y a des _couches_ d'une _terre martiale_ fort brune et sans liaison: d'autres, au contraire toujours _martiales_, sont très dures et renferment de très beau jaspe sanguin: d'autres enfin sont de vrai _marbre_ gris veinées de rouge. C'est dans ce marbre que font les _corps marins_, savoir des coquillages et des spongites; et il est lui-même martial comme tout le reste: les mineurs le nomment _Kubrimen_, et ne l'employent que comme un _fondant_ pour d'autres _minéraux de fer_.

"A ce _filon_, s'en joignent d'autres plus embarrassans. Ils viennent du _toit_, qu'ils divisent par de larges _fentes_ comblées, aboutissantes au _filon_ principale. Ils font de même _calcaires_ et marins faits par _couches_; mais ces _couches_ ont une si grande inclinaison, que je ne puis les comprendre: il faut qu'il y ait eu d'étranges bouleversemens dans ces endroits-là[27].

[Note 27: Here, no doubt, are appearances which it is impossible to explain by the theory of infiltration; it is the filling of mineral veins, and their branches or ramifications, with marble containing marks of marine objects. But, if we shall suppose this marble to have been in the fluid state of fusion, as well as the iron-ore and jasper, we may easily conceive it introduced into the principal vein and its branches. The description here given of those appearances is by no means such as to enable us to judge particularly of this case, which surely merits the most accurate investigation, and which, I doubt not, will give physical demonstration of the fusion of those mineral substances. I know that shells have been found within the body of veins in Germany; but, a stratification of those materials in a vein was never heard of before, so far as I know.]

"Ces _fentes_ se sont faites, et ont été remplies, dans la _mer_; puisque les matières qui les remplissent sont de la classe de ses dépôts très connoissables, et qu'il contiennent des _dépouilles marines_. Mais ce qui embarrasse alors c'est que les autres _filons_ ne soyent pas dans le même cas. N'est ce point là encore un indice, que ces _fentes_ out été d'abord et principalement remplies de matières, poussées du fond par la même force qui secouoit les montagnes[28].

[Note 28: But what is this power by which matter is to be forced from the bottom of the sea to the top of the mountains? For, unless we can form some idea of that power which, as a cause, we ascribe to the perceived effect, we either say nothing to the purpose, or we employ a preternatural cause. It is not sufficient to imagine a power capable of raising from the bottom of the sea the materials deposited in the abyss; it is also necessary to find a power capable of softening bodies which are hard, and of thus consolidating those masses which are formed of loose or unconnected materials. Such a power, indeed, the present theory assumes; and, so far as this shall be implied in the supposition of our author, it will thus have received a certain conformation.]

"Ce _filon_ n'est pas le seul dans le _Hartz_ qui donne des signes _marins_. Il y en a un autre, qui même se rapproche davantage de la nature du commun des _filons_, et où l'on trouve aussi des _coquillages_. C'est celui de _Haus-Hartzbergerzug_, pres de _Clausthal_, où, dans les _Halles_ de quelques mines de plomb abandonnées, et dans une forte _d'ardoise_, on trouve de petites _moules_ ou _tellines_ striées, d'une espèce particulière que j'ai vue dans des _ardoises secondaires d'Arotzen_ en _Waldek_ et de _Sombernon_ en _Bourgogne_. Il y a donc certainement quelques _filons_ faits par les dépôts de la _mer_ dans les _fentes_ de montagnes _primordiales_; comme au contraire il y a des _filons_ métalliques sans indices _marins_, dans des montagnes évidemment _secondaires_, telles que celles de _Derbyshire_, ou les _filons_ de _plomb_ traversent des couches de _pierre à chaux_."

Here again our author seems to me to refute his own supposition, That a chasm in the schistus rock may have existed at the bottom of the sea, and been then filled from above with such materials as were transported by the moving water to that place, is not impossible; but nobody, who knows the nature of a common metallic vein, can ever suppose it to have been filled in that manner. Our author then adds, "On ne fait réellement que commencer dans ce genre d'observations, considérées quant à la Cosmologie; ainsi il ne faut point désespérer que tout cela ne se dévoile un jour, et que nous n'acquerrions ainsi un peu plus de connoissance sur ce qui se passoit dans la _mer ancienne_.

"En revenant vers _Elbingerode_, nous retrouvâmes ces _schistes_, qui paroissent au travers des _marbres:_ ils sont donc la continuation de la masse _schisteuse_ à laquelle appartient le _filon_, dont je viens de parler. Ce _filon_ à été formé dans une _fente_, restée ouverte et vide: les dépôts de la _mer_ l'ont comblée, en même tems qu'ils formoient les couches de _marbre_, qui sont à l'extérieur. En effet, ce _filon_ contient des _couches marines ferrugineuses_, de la même nature que celles des collines calcaires voisines formées sur le schiste.

"Nous partîmes _d'Elbingerode_ dans l'après midi pour nous rapprocher de Clausthal. Notre chemin fut encore quelque tems sur des sommités _calcaires_; et avant que d'en sortir, nous trouvâmes une autre mine singulière à _Arenfeld_. C'est encore un vrai _filon_; mais dans une montagne de _pierre à chaux:_ C'est à-dire, que cette montagne a aussi été _fendue_, et que la _fente_ a été remplie d'une _gangue_. La matière de ce _filon_ est encore _calcaire_ en plus grande partie; mais cette _pierre à chaux_ distincte est _ferrugineuse_, et parsemée de concrétions de _jaspe_ comme celles _d'Elbingerode:_ on y trouve aussi une matière verdâtre, qui, comme le _jaspe_, ne fait pas effervescence avec l'eau forte."

Here is a phenomenon which is altogether incompatible with the theory that this author has given us for the explanation of those appearances. He supposes empty crevices in the schistus mountains at the bottom of the sea; these crevices he supposes filled by the deposits of the sea, at the same time, and with the same materials with which the lime-stone strata were formed above the schistus mountains; but we find one of those same veins in these secondary calcareous strata. Now, tho' we should be disposed to allow, that, in the primordial mountain, of which we are supposed not to know the origin, there might have been empty crevices which were afterwards filled with materials transported by the sea, this cannot be admitted as taking place in the loose or incoherent materials deposited above the schistus. Consequently, this theory of our author, which is evidently erroneous with regard to the veins in the lime-stone, must, in the other case, be at least examined with a jealous eye.

"Le haut de cette partie des montagnes _calcaires_ étoit encore recouvert de _sable_ et de grès _vitrescibles_: et continuant à marcher, sans aucune inflexion sensible, nous nous trouvâmes subitement sur les _schistes_; d'où nous montâmes plus rapidement. Puis traversant quelques petites vallées nous arrivâmes sur les montagnes qui appartiennent au prolongement du _Brocken_ ou _Blocksberg_. La matière dominante est alors le _granit_; mais il est tout en blocs le long de cette route, et ces blocs se trouvent à une telle distance de tout sommité intacte de cette pierre, qui est aisé de juger non seulement qu'ils ne sont pas dans leur place originaire, mais encore qu'il ne sont arrivés là par aucune des causes naturelles qui agissent dans les montagnes; savoir, la pesanteur, la pente, et le cours des eaux. Ce sont donc de violentes explosions qui ont dispersé ces blocs; et alors ils deviennent un nouveau trait cosmologique de quelque importance: car rien ne se meut, ni ne paroît s'être mu depuis bien des siècles, dans ces lieux qui montrent tant de désordre: un tapis de verdure couvre tout, en conservant les contours baroques du sol. Le bétail ne sauroit pâturer dans de telles prairies; mais l'industrieux montagnard fait y faucher[29].

[Note 29: M. de Saussure endeavours to explain those appearances of transported blocks of granite by another cause; this is a certain _debacle_ of the waters of the earth, which I do not understand. M. de Luc again attempts to explain it by violent explosions; I suppose he means those of a volcano. But he has not given us the evidence upon which such an opinion may be founded, farther than by saying that those blocks could not have come there by the natural operations of the surface. By this must be meant, that, from the nearest summit of granite, there is not, at present, any natural means by which these blocks might be transported to that place. But it is not with the present state of things that we are concerned, in explaining the operations of a distant period. If the natural operations of the surface change the shape of things, as is clearly proved by every natural appearance, Why form an argument against a former transaction, upon the circumstances of the present state of things? Our author does not seem to perceive, that, from this mode of reasoning, there is is an insuperable objection to his violent explosions having been employed in producing those effects. For, had there been such a cause, the evidence of this must have remained; if the surface of the earth does not undergo great changes: If, again, this surface be in time much changed, How can we judge from the present shape, what might have been the former posture of things?

This author, indeed, does not allow much time for the natural operations of the globe to change its surface; but, if things be not greatly removed from the state in which the violent operations of the globe had placed them, Why does he not point out to us the source of this great disorder which he there perceives? From what explosion will be explained the blocks of granite which are found upon the Jura, and which must have come from the mass of _Mont Blanc_? If these dispersed blocks of stone are to be explained by explosion, there must: have been similar explosions in other countries where there is not the smallest appearance of volcanic eruptions; for, around all our granite mountains, and I believe all others, there are found many blocks of granite, traveled at a great distance, and in all directions.]

"_Oberbruck_, ou nous avions été la précédente fois, se trouva sur notre route, et nous y passames aussi la nuit, dans l'espérance de pouvoir monter le lendemain sur le _Brocken_; mais il fut encore enveloppé de nuages; ainsi nous continuâmes à marcher vers _Clausthal_, passant de nouveau par le _Bruchberg_, où le _sable_ et ses gres recouvrent le _schiste_; puis arrivant à une autre sommité, nous y trouvâmes la même pierre _sableuse_ par couches, mêlée de parcelles de _schiste_, que nous avions vue sur les montagnes _calcaires d'Elbingerode_. Il est donc toujours plus certain que le sol primordial de toutes ces montagnes existoit sous les eaux de l'ancienne mer; puisqu'il est recouvert de diverses fortes de dépôts, connus pour appartenir à la _mer_; et que les _fentes_ des _filons_ existoient dans cette _mer ancienne_; puisqu'elle en a rempli elle-même quelques unes, et qu'elle a recouvert de ses dépôts quelques autres _filons_ tout formés. Quant à celles des matières de ces _filons_, qui ne paroissent pas être _marines_ (et c'est de beaucoup la plus grande quantité), j'ai toujours plus de penchant d'en attribuer une partie à l'opération des _feux souterreins_, à mesure que je vois diminuer la probabilité de les assigner entièrement à _l'eau_. Mais quoi-qu'il en soit, ces gangues ne font pas de même date que les montagnes[30].

[Note 30: I most willingly admit the justness of our author's view, if he thus perceives the operation of fire in the solids of our earth; but it is not for the reasons he has given us for discovering it here more than in other places; for there is not a mineral vein, (so far at least as I have seen), in which the appearances may be explained by any thing else besides the operation of fire or fusion. It is not easy to conceive in what manner our author had conceived the opinions which he has displayed in these letters. He had no opinion of this kind, or rather he was persuaded that subterraneous fire had no hand in the formation of this earth before he came to this place of the Hartz; here he finds certain appearances, by which he is confirmed in his former opinion, that water had operated in forming mineral veins; and then he forms the idea that subterraneous fire may have operated also. But, before the discovery of the chasms in the schistus mountains having been filled with the stratified materials of the sea, How had he supposed veins to be filled? If this philosopher had before no opinion of subterraneous fire, as instrumental in that operation, How comes he now to change that former opinion? For, unless it be the extraordinary manner of filling these open crevices in the mountains by matter deposited immediately from the sea, there is certainly no other appearance in this mineral country of the Hartz, that may not be found in any other, only perhaps upon a smaller scale.]

"Le lendemain de notre arrivée a _Clausthal_, qui étoit le 13e, nous allâmes visiter d'autres mines de _fer_ en montagnes secondaires, situées au côté opposé du Hartz. Elles sont auprès de _Grund_ l'une des _villes de mines_, et près du lieu ou sortira la nouvelle _galerie d'écoulement_ à laquelle on travaille, etc.

"Arrivés à _Grund_ les officiers mineurs vinrent, comme à l'ordinaire, accompagner Mons. de _Reden_ aux _mines_ de leur département. Celles-ci, sans être plus extraordinaires que celles qui nous avions vues à _Elbingerod_, ou sans aider mieux jusqu'ici à expliquer ce qu'elles ont toutes d'extraordinaire, nous donnent au moins des indices probables de grands accidens. Ces montagnes de _Grund_ sont encore de l'espèce remarquable, dont la base est de _schiste_, et le haut de _pierre à chaux_. Les mines qu'on y exploit sont de _fer_, et se trouvent dans cette matière _calcaire_; mais elles y sont sous des apparences tout-à-fait étranges. La montagne où nous les vîmes principalement le nomme _Iberg_. On y poursuit des masses de _pierre à fer_, de l'ensemble desquelles les mineurs ne peuvent encore se rendre compte d'une manière claire. Ils ont trouvé dans cette montagne des _ca__vernes_, qui ressemblent à l'encaissement de _sillons_ déjà exploités, ou non formés; c'est-à-dire, que ce sont des _fentes_ presque verticales, et vides, Le _minerai_ qu'ils poursuivent est en _Rognons_; c'est à dire, en grandes masses sans continuité décidée. Cependant ces masses semblent se succéder dans la montagne suivant une certaine direction; tellement que les mineurs savent déjà les chercher, par des indices d'habitude. La substance de cette _pierre à fer_ particulière renferme des crystallizations de diverses espèces. Il y a des _druses de quartz_, ou de petits cristaux de quartz qui tapissent des cavités; il y a aussi du _spath_ commun, et de celui qu'on nomme pesant; on y trouve enfin une forte de crystallization nommée _Eisenman_ (_homme de fer_) par les mineurs; se sont des amas de cristaux noir-âtres, qui ressemblent à des groupes de grandes lentilles plattes, et ces cristaux sont _ferrugineux_.

"Entre les signes de bouleversement que renferme ce lieu, est un rocher nommé _Gebichensten_, qui est en _pierre à chaux_, ce que _l'Ebrenbreitstein_ de _Coblentz_ est en pierre sableuse: c'est-à-dire, que ses _couches_, remplies de _corps marins_, sont presque verticales; ceux de ces corps qu'on y trouve en plus grande quantité, sont des _madrépores_. Ce rocher s'élève comme un grand obélisque, au-dessus des _cavernes_, dont j'ai parlé; montrant par le côté ses _couches_, qui se trouvent, comme je l'ai dit, dans une situation presque verticale. Sa base est déjà bien minée, tant par les _cavernes_, que par la _pierre à fer_ qu'on en tire; et je ne me hasardai dessus, que parce que je me dis, qu'il y a des millions contre un à parier, que ce n'est pas le moment où il s'enfoncerait. Mais je n'en dirois pas autant, s'il s'agissoit de m'y loger à demeure.

"Quoique tout ce lieu là soit fort remarquable, il se pourrait que ce ne fut qu'un phénomène particulier. Les _cavernes_ peuvent devoir leur origine à la même cause que celle de Schartzfeld; et le dérangement des rochers supérieurs à des enfoncemens occasionnés par ces _cavernes_. Rien n'est si difficile que de retracer aujourd'hui ces fortes d'accidens à cause des changemens que le tems y a opérés. S'ils sont arrivés sous les eaux de la _mer_, on conçoit aisément les altérations qui ont dû succéder; et si c'est depuis que nos continens sont à sec, les eaux encore, tant intérieures qu'extérieures, et la végétation, en ont beaucoup changé l'aspect."

This author has a theory by which he explains to himself the former residence of the sea, above the summits of our mountains; this, however, is not the theory by which we are now endeavouring to explain appearances; we must therefore be allowed to reason from our own principles, in considering the facts here set forth by our author.

Nothing, I think, is more evident, than that in this mineral country of the Hartz, we may find the clearest marks of fracture, elevation, and dislocation of the strata, and of the introduction of foreign matter among those separated bodies. All those appearances, our author would have to be nothing but some particular accident, which is not to enter into the physiology of the earth. I wish again to generalise these facts, by finding them universal in relation to the globe, and necessarily to be found in all the consolidated parts of our land.

It was not to refute our author's reasoning that I have here introduced so much of his observations, but to give an extensive view of the mineral structure of this interesting country. This therefore being done, we now proceed to what is more peculiarly our business in this place, or the immediate subject of investigation, viz. the distinction of primary and secondary strata.

"Dans le voisinage de cette montagne, il y a une autre fort intéressante, que je vis le jour suivant. Quoiqu'en traitant des volcans, j'aie démontré que la formation des montagnes, par soulèvement, étoit sans exemple dans les faits, et sans fondement dans la théorie, je ne laisseroi pas de m'arrêter au phénomène que présente cette montagne; parce qu'il prouvera directement que les _couches calcaires_ au moins, ont été formées _à la hauteur ou elles sont_; c'est-a-dire qu'elles n'ont pas été soulevées.

"Voulant prendre l'occasion de mon retour à _Hanovre_, pour traverser les avant-corps du _Hartz_, dans quelque nouvelle direction; je résolus de faire ce voyage à cheval, et de prendre ma route droite vers _Hanovre_, au-travers des collines; ce qui me conduisit encore à _Grund_ puis à _Münchehof Brunshausen, Engelade, Winsenburg_ et _Alfeld_, où enfin, traversant la _Leine_ j'entrai dans la grande route.

"Je quittai donc _Clausthal_ (et avec bien du regret) le 14 au matin; et revenant d'abord à _Grund_, je le laissai sur ma droite, ainsi que _l'Iberg_; et plus loin, du même côté, une autre montagne nommée _Winterberg_ dont la base est _schiste_, et le sommet plus haut que Clausthal, entièrement composé de _couches calcaires_. De _Grund_ je montai vers une montagne nommée _Ost Kamp_; et je commençai là à donner une attention particulière au sol. Le long de mon chemin, je ne trouvai longtemps que des schistes, qui montroient leurs points en haut, comme à l'ordinaire, et avec tous leurs tortillemens de feuillets. Mais arrivé au haut de la montagne, j'y vis des carrières de _pierre à chaux_, où les couches absolument régulières, et qui ont peu d'épaisseur sur le _schiste_ suivent parfaitement les contours du _sommet_. Ces lits de _pierre à chaux_ n'ont certainement pas été soulevés du fond de la _mer_ sur le dos des schistes; lors même qu'à cause de la grande inclinaison des feuillets de ceux-ci on voudroit le attribuer à quelque révolution telle que le _soulèvement_; (ce que je n'admettrois point). Car si ces lits _calcaires_, ayant été faits au fond de la _mer_, avoyent été soulevés avec les schistes, ne feroient-ils pas brisés et bouleversés comme eux? Il est donc evident, que quoiqu'il soi arrivé au schiste qui les porte, ces lits, et tous les autres de même genre qui sont au haut de ces montagnes, ont été déposées au niveau où ils sont; et que par conséquent la _mer_ les surpassoit alors. Ainsi le système de soulèvement perd son but, s'il tend à expliquer pourquoi nous avons des _couches_, formées par la mer, qui se trouvent maintenant si fort au dessus de son niveau. Il est évident que ces _couches_ n'ont pas été soulevées; mais que la _mer_ s'est _abaissée_. Or c'est là le grand point cosmologique à expliquer: tous les autres, qui tiennent à la structure de certaines montagnes inintelligibles, n'appartiendront qu'à _l'histoire naturelle_, tant qu'ils ne se lieront pas avec celui-la."

Here are two things to be considered; the interesting facts described by our author, and the inference that he would have us draw from those facts. It would appear from the facts, that the body of schistus below, and that of lime-stone above, had not undergone the same disordering operations, or by no means in the same degree. But our author has formed another conclusion; he says, that these lime-stone strata must have been formed precisely in the place and order in which they lie at present; and the reason for this is, because these strata appeared to him to follow perfectly the contour of the summit of this mountain. Now, had there been in the top of this mountain a deep hollow encompassed about with the schistus rock; and had this cavity been now found filled with horizontal strata, there might have been some shadow of reason for supposing those strata to have been deposited upon the top of the mountain. But to suppose, _first_, that shells and corals should be deposited upon the convex summit of a mountain which was then covered by the sea; _secondly_, that these moveable materials should remain upon the summit, while the sea had changed its place; and, _lastly_, that those shells and corals left by the sea upon the top of a mountain should become strata of solid limestone, and have also metallic veins in it, certainly holds of no principle of natural philosophy that I am acquainted with. If, therefore, such an appearance as this were to be employed either in illustration or confirmation of a theory, it would itself require to be explained; but this is a task that this cosmologists does not seem willing to undertake.

He has formed a hypothesis for explaining the general appearance of that which was once the bottom of the sea being now found forming the summits of our mountains; but surely this philosopher will acknowledge, that those natural appearances, in any particular place, will be the same, whether we suppose the bottom of the sea to have been raised, as in the present theory, or the surface of the sea to have sunk according to his hypothesis. For, it is equally easy to suppose a portion of the earth to have been raised all this height, as to suppose all the rest of the surface of the globe to have sunk an equal space, while a small portion of the bottom of the sea, remaining here and there fixed in its place, became the highest portion of the globe. Consequently, whatever evidence this philosopher shall find in support of his theory of the present earth, (a subject which it is not our purpose to examine) it cannot be allowed that he has here brought any argument capable of disproving the elevation of the bottom of the sea; a supposition which other theories may require.

I would now observe, in relation to the present theory, that so far as this author has reasoned justly from natural appearances, his conclusions will be found to confirm the present supposition, that there is to be perceived the distinction of primordial, and that of secondary, in the masses of this earth, without altering the general theory either with respect to the original formation of those masses, or to their posterior production.

Here one of two things must be allowed; either that those strata of schistus had been broken and distorted under a mass of other superincumbent strata; or that those superincumbent strata had been deposited upon the broken and distorted strata at the bottom of the sea. Our author, who has examined the subject, inclines to think, that this last has been the case. If, therefore, strata had been deposited upon broken and bare rocks of schistus, it is probable that these had been sunk in the sea after having been exposed to the atmosphere, and served the purpose of land upon the globe.[31]

[Note 31: This is also supported by another very interesting observation contained in this letter. M. de Luc observes, that in this country the schistus is generally covered by strata of lime-stone, and that these lime-stone strata are again covered with those of sand-stone, in which are found a great many fragments of schistus lying flat. Therefore, while those sand-stone strata were collecting at the bottom of the sea, there had been rocks of schistus in some other place, from whence those fragments bad been detached.]

An example of the same kind also occurs in the _Discours sur l'Histoire Naturelle de la Suisse_; and this author of the _Tableaux de la Suisse_ has given a very distinct description of that appearance, which is perhaps the more to be valued as a piece of natural history, as this intelligent author does not pretend to any geological theory, but simply narrates what he has seen, with such pertinent observations on the subject as naturally must occur to a thinking person on the spot.--(Discours, etc. page 228. Entrée au pays de Grisons).

"Du village d'Elen on continue à monter le reste du petit vallon pendant une lieue et demie parmi les mêmes espèces de pierres qu'on vient de décrire; en passant au travers de bois et de forêts de sapins et de quelques pâturages dont ce haut est couvert, on parvient au pied du Bundnerberg, montagne des grisons, qui forme la tête du vallon. On laisse à droite un fond ou espèce d'entonnoir, entouré de très-hautes montagnes inaccessibles, pour s'enfourrer à gauche entre des rochers qui font fort resserrés, où coule un torrent. Ce lieu seroit horreur si on ne se trouvoit accoutumé, par degrés, à voir de ces positions effrayantes: tout y est aride, il n'y a plus d'arbres ni de végétaux ce sont des rochers entassés les un sur les autres; ce lieu paroit d'autant plus affreux que le passage a été subit, et qu'en sortant de bois et des forêts, on se trouve tout-à-coup parmi ces rochers qui s'élèvent comme des murailles, et dont on ne voit pas la cime; cette gorge ou cette entrée qui se nomme Jetz, est la communication du Canton du Glaris aux Gritons; on a dit précédemment qu'il y en avoit une plus aisée par le Gros-Thal ou le grand vallon. Ce passage est très-curieux pour la Lithogeognosie, il est rare de trouver autant de phénomènes intéressans rassemblés, et des substances aussi variées par rapport à leurs positions; c'est le local qui mérite le plus d'être examiné en Suisse, et la plus difficile que nous ayons parcouru. On se souviendra que nous avons continuellement monté depuis Glaris, et que nous nous trouvons au pied de ces montagnes ou de ces pics étonnans qui dominent les hautes Alpes; on trouve ici la facilité peu commune de pouvoir examiner, et voir le pied ou les fondemens de ces colosses qui couronnent le globe, parce qu'ils sont ordinairement entourés de leurs débris et de leurs éboulemens qui en cachent le pied. Ici c'est une roche de schiste bleuâtre, dure et compact, traversée de filons de quartz blanc, et quelquefois jaunâtre, dans laquelle on a taillé un sentier pour pouvoir en franchir le pied. Cette roche s'élève à une hauteur prodigieuse, est presque verticale, et ces couches sont à quatre-vingt degrés d'inclinaison. L'imagination est effrayée de voir que de pareilles masses ayent pu être ébranlées et déplacées au point d'avoir fait presque un quart de conversion. Après avoir monté et suivi cette roche parmi les pierres et les décombres, une heure et demie, on trouve cette roche de schiste surmontée d'autres rochers fort hauts qui sont calcaires, et dont les lits sont fort horizontaux. Les schistes, qui sont directement sous les roches calcaires, conservent la même inclinaison qu'elles ont à leur pied."

Here is an observation which certainly agrees with that given by M. de Luc, and would seem to confirm this conclusion, that strata had been deposited upon those _schisti_ after they had been changed from their natural or horizontal position, and become vertical; at the same time, this conclusion is not of necessary consequence, without examining concomitant appearances, and finding particular marks by which this operation might be traced; for the simply finding horizontal strata, placed above vertical or much inclined schiste, is not sufficient, of itself, to constitute that fact, while it is acknowledged that every species of fracture, dislocation, and contortion, is to be found among the displaced strata of the globe.

Since writing this chapter, I am enabled to speak more decisively upon that point, having acquired more light upon the subject, as will appear in the next chapter.

CHAP. VI.

The Theory of interchanging Sea and Land illustrated by an Investigation of the Primary and Secondary Strata.

SECT. I.--A distinct View of the Primary and Secondary Strata.

Having given a view of what seems to be the primary and secondary strata, from the observations of authors, and having given what was my opinion when I first wrote that chapter, I am now to treat of this subject from observations of my own, which I made since forming that opinion.

From Portpatrick, on the west coast, to St Abb's Head, on the east, there is a tract of schistus mountains, in which the strata are generally much inclined, or approaching to the vertical situation; and it is in these inclined strata that geologists allege that there is not to be found any vestige of organised body. This opinion, however, I have now proved to be erroneous.

There cannot be any doubt with regard to the original formation of those stratified bodies, as having been formed of the materials that are natural to this earth, viz. the detritus of former bodies; and as having been deposited in water, like the horizontal strata: For the substances and bodies of which they are visibly composed are no other than those which form the most regular horizontal strata, and which are continually traveling, or transported at the bottom of the sea, such as gravel, and sand, argillaceous and micaceous bodies.

On each side of this ridge of mountains, which towards the east end is but narrow, there is a lower country composed of strata in general more horizontal; and among which strata, besides coal, there are also found the relics of organised bodies.

Abstracting at present from any consideration of organised bodies among the materials of those strata, it may be affirmed, that the materials which form the strata in the mountains and in the low country, are similar, or of the same nature; that they have, in both places, been consolidated by the same means, viz. heat and fusion; and that the same or similar accidents have happened to them, such as change from their original position, and mineral veins traversing them in various shapes. Yet still there is a distinctive character for those two bodies, the alpine and the horizontal strata; for, while the horizontal position appears natural to the one, and the changes from that particular state to be only an accident, the vertical position appears to be more natural to the other, which is seldom found horizontal.

Therefore, altho' it is unquestionable that the strata in the alpine and low countries had the same or a similar original, yet, as the vertical position, which is the greatest possible change in that respect, is more natural to the alpine strata, or only necessary in the natural order of those bodies, we are to consider this great disorder or change from the natural state of their original formation, as the proper character of those alpine strata. But then it is also necessary to include in this character a general hardness and solidity in those vertical strata, otherwise they would not have been properly alpine, or have resisted the wearing and washing powers of the globe, so as to have remained higher than the others; for, the vertical position, or great inclination of those strata, should rather have disposed them the more to dissolution and decay. Let us now see how far we shall be justified in that general conclusion, by the examination of those bodies.

The fact is certain, that those alpine bodies are much harder, or less subject to dissolution and decay, than the horizontal strata. But this must be taken in the general, and will by no means apply to particular cases which might be compared. Nothing, for example, more solid than the lime-stones, or marbles, and iron-stones; nothing more hard or solid than the chirt or flint; and all these are found among the horizontal strata. But, while some strata among those horizontal beds are thus perfectly solid, others are found with so slight degrees of consolidation, that we should not be able to ascribe it to the proper cause, without that gradation of the effect, which leads us to impute the slightest degree of consolidation to the same operations that have produced the complete solidity. While, therefore, the most perfect solidity is found in certain strata, or occasionally among the horizontal bodies, this forms no part of their character in general, or cannot be considered as a distinctive mark, as it truly is with regard to the alpine strata. These last have a general character of consolidation and indissolubility, which is in a manner universal. We are, therefore, now to inquire into the cause of this distinction, and to form some hypothesis that may be tried by the actual state of things, in being compared with natural appearances.

As the general cause of consolidation among mineral bodies, formed originally of loose materials, has been found to consist in certain degrees of fusion or cementation of those materials by means of heat; and as, in the examination of the horizontal strata we actually find very different degrees of consolidation in the several strata, independent of their positions in relation to height or depth, we have reason to believe that the heat, or consolidating operation, has not been equally employed in relation to them all.

We are not now inquiring how an inferior stratum should have been heated in a lesser degree, or not consolidated, while a superior stratum had been consolidated in the most perfect manner; we are to reason upon a fact, which is, that the horizontal strata in general appear not to have been equally or universally consolidated; and this we must attribute to an insufficient exertion of the consolidating cause. But, so far as the erecting cause is considered as the same with that by which the elevated bodies were consolidated, and so far as the vertical situation is a proof of the great exertion of that subterraneous power, the strata which are most erected, should in general be found most consolidated.

Nothing more certain than that there have been several repeated operations of the mineralising power exerted upon the strata in particular places; and all those mineral operations tend to consolidation: Therefore, the more the operations have been repeated in any place, the more we should find the strata consolidated, or changed from their natural state. Vertical strata have every appearance from whence we should be led to conclude, that much of the mineral power had been exerted upon them, in changing their original constitution or appearance. But the question now to be considered is this, How far it may appear that these masses of matter, which now seem to be so different from the ordinary strata of the globe, had been twice subjected to the mineral operations, in having been first consolidated and erected into the place of land, and afterwards sunk below the bottom of the sea, in order a second time to undergo the process of subterraneous heat, and again be elevated into the place where they now are found.

It must be evident, here is a question that may not be easy to decide. It is not to the degree of any change to which bodies may be subject, that we are to appeal, in order to clear up the point in question, but to a regular course of operations, which must appear to have been successively transacted, and by which the different circumstances or situations of those masses are to be discovered in their present state. Now, though it does not concern the present theory that this question be decided, as it is nothing but a repetition of the same operations that we look for; nevertheless, it would be an interesting fact in the natural history of this earth; and it would add great lustre to a theory by which so great, so many operations were to be explained. I am far from being sanguine in my expectations of giving all the satisfaction in relation to this subject that I could wish; but it will be proper to state what I have lately learned with regard to so curious a question, that others, who shall have the opportunity, may be led to inquire, and that thus the natural history of the earth may be enlarged, by a proper investigation of its mineral operations.

With this view I have often considered our schistus mountains, both in the north and south; but I never found any satisfactory appearance from whence conclusions could be formed, whether for the question or against it. The places I examined were those between the alpine countries and the horizontal strata; here, indeed, I have frequently found a confused mass, formed of the fragments of those alpine strata mixed with the materials of the horizontal bodies; but not having seen the proper shape and connection of those several deposits, I always suspended my judgment with regard to the particular operations which might have been employed in producing those appearances.

I had long looked for the immediate junction of the secondary or low country strata with the alpine schistus, without finding it; the first place in which I observed it was at the north end of the island of Arran, at the mouth of Loch Ranza; it was upon the shore, where the inclined strata appeared bare, being; washed by the sea. It was but a very small part that I could see; but what appeared was most distinct. Here the schistus and the sandstone strata both rise inclined at an angle of about 45°; but these primary and secondary strata were inclined in almost opposite directions; and thus they met together like the two sides of a _lambda_, or the rigging of a house, being a little in disorder at the angle of their junction. From this situation of those two different masses of strata, it is evidently impossible that either of them could have been formed originally in that position; therefore, I could not here learn in what state the schistus strata had been in when those of the sand-stone, &c, had been superinduced.

Such was the state of my mind, in relation to that subject:, when at Jedburgh upon a visit to a friend, after I had returned from Arran, and wrote the history of that journey; I there considered myself as among the horizontal strata which had first appeared after passing the Tweed, and before arriving at the Tiviot. The strata there, as in Berwickshire, which is their continuation to the east, are remarkably horizontal for Scotland; and they consist of alternated beds of sand-stone and marl, or argillaceous and micaceous strata. These horizontal strata are traversed in places with small veins of whin-stone, as well as greater masses forming rocks and hills of that material; but, except it be these, (of which there are some curious examples), I thought there could be nothing more of an interesting nature to observe. Chance, however, discovered to me what I could not have expected or foreseen.

The river Tweed, below Melrose, discovers in its bed the vertical strata of the schistus mountains, and though here these indurated bodies are not veined with quartz as in many places of the mountains, I did not hesitate to consider them as the same species, that is to say, the marly materials indurated and consolidated in those operations by which they had been so much changed in their place and natural position. Afterwards in travelling south, and seeing the horizontal softer strata, I concluded that I had got out of the alpine country, and supposed that no more of the vertical strata were to be observed.

The river Tiviot has made a wide valley as might have been expected, in running over thole horizontal strata of marly or decaying substances; and the banks of this river declining gradually are covered with gravel and soil, and show little of the solid strata of the country. This, however, is not the case with the Jed, which is to the southward of the Tiviot; that river, in many places, runs upon the horizontal strata, and undermines steep banks, which falling shows high and beautiful sections of the regular horizontal strata. The little rivulets also which fall into the Jed have hollowed out deep gullies in the land, and show the uniformity of the horizontal strata.

In this manner I was disposed to look for nothing more than what I had seen among those mineral bodies, when one day, walking in the beautiful valley above the town of Jedburgh, I was surprised with the appearance of vertical strata in the bed of the river, where I was certain that the banks were composed of horizontal strata. I was soon satisfied with regard to this phenomenon, and rejoiced at my good fortune in stumbling upon an object so interesting to the natural history of the earth, and which I had been long looking for in vain.

Here the vertical strata, similar to those that are in the bed of the Tweed, appear; and above those vertical strata, are placed the horizontal beds, which extend along the whole country.

The question which we would wish to have solved is this; if the vertical strata had been broken and erected under the superincumbent horizontal strata; or if, after the vertical strata had been broken and erected, the horizontal strata had been deposited upon the vertical strata, then forming the bottom of the sea. That strata, which are regular and horizontal in one place, should be found bended, broken, or disordered at another, is not uncommon; it is always found more or less in all our horizontal strata. Now, to what length this disordering operation might have been carried, among strata under others, without disturbing the order and continuity of those above, may perhaps be difficult to determine; but here, in this present case, is the greatest disturbance of the under strata, and a very great regularity among those above. Here at least is the most difficult case of this kind to conceive, if we are to suppose that the upper strata had been deposited before those below had been broken and erected.