de cet ordre secondaire d'anciennes roches, par tous les systèmes de
montagnes qui appartiennent à l'Empire Russe. La chaîne Ouralique, par
exemple, a du côté de l'Orient sur tout sa longueur, une très-grande
abondance de schistes cornés, serpentins et talceux, riches en filons
de cuivre, qui forment le principal accompagnement du granite, et en
jaspres de diverses couleurs plus extérieurs et souvent comme entrelacés
avec les premiers, mais formant des suites de montagnes entières, et
occupant de très-grands espaces. De ce même côté, il y paraît beaucoup
de quartz en grandes roches toutes pures, tant dans la principale chaîne
que dans le noyau des montagnes de jaspre, et jusques dans la plaine.
Les marbres spateux et veinés, percent en beaucoup d'endroits. La
plupart de ces espèces ne paraissent point du tout à la lisière
occidentale de la chaîne, qui n'est presque que de roche mélangée de
schistes argileux, alumineux, phlogistique, etc. Les filons des mines
d'or mêlées, les riches mines de cuivre en veines et chambrées, les
mines de fer et d'aimant par amas et montagnes entières, sont l'apanage
de la bande schisteuse orientale; tandis que l'occidentale n'a pour elle
que des mines de fer de dépôts, et se montre généralement très-pauvre en
métaux. Le granit de la chaîne qui borde la Sibérie, est recouvert du
côté que nous connaissons de roches cornées de la nature des pierres à
fusil, quelquefois tendant à la nature d'un grais fin et de schistes
très-métallières de différente composition. Le jaspre n'y est qu'en
filons, ou plans obliques, ce qui est très-rare pour la chaîne
Ouralique, et s'observe dans la plus grande partie de la Sibérie, à
l'exception de cette partie de sa chaîne qui passe près de la mer
d'Okhotsk, ou le jaspre forme derechef des suites de montagnes, ainsi
que nous venons de le dire des monts Ourals; mais comme cette roche
tient ici le côté méridionale de la chaîne Sibérienne, et que nous
ne lui connaissons point ce côté sur le reste de sa longueur, il se
pourrait que le jaspre y fût aussi abondant. Il faudrait, au reste, bien
plus de fouilles et d observations pour établir quelque chose de certain
sur l'ordre respectif qu'observent ces roches."
I would now ask, if in all this account of the gradation of rock from
the Oural mountains to the sandy coast of the Baltic, there is to be
observed any clear and distinctive mark of primitive, secondary, and
tertiary, mountains, farther than as one stratum may be considered as
either prior or posterior to another stratum, according to the order of
superposition in which they are found. We have every where evident marks
of the formation of strata by materials deposited originally in water;
for the most part, there is sufficient proof that this water in which
those materials had been deposited was the sea; we are likewise assured
that the operations of this living world producing animals, must
have, for a course of time, altogether inconceivably been exerted,
in preparing materials for this mass; and, lastly, from the changed
constitution of those masses, we may infer certain mineral operations
that melt the substance and alter the position of those horizontal
bodies. Such is the information which we may collect from this mineral
description of the Russian Dominions.
If we compare some of the Oural mountains with the general strata of
the Russian plains, then, as to the contained minerals, we may find a
certain diversity in those two places; at the same time, no greater
perhaps than may be found betwixt two different bodies in those same
plains, for example, chalk and flint. But when we consider those bodies
of the earth, or solid strata of the globe, in relation to their proper
structure and formation, we surely can find in this description nothing
on which may be founded any solid opinion with regard to a different
original, however important conclusions may perhaps be formed with
regard to the operations of the globe, from the peculiar appearances
found in alpine.
From this detail of what is found in the Oural mountains, and in the
gradation of country from those mountains to the plains of Russia, we
have several facts that are worthy of observation. First extensive
mountains of jasper. I have a specimen of this stone; it is striped red
and green like some of our marly strata. It has evidently been formed of
such argillaceous and siliceous materials, not only indurated, so as to
lose its character, as an argillaceous stone, but to have been brought
into that degree of fusion which produces perfect solidity. Of the same
kind are those hornstein rocks of the nature of flint, sometimes tending
to the nature of a fine sandstone. Here is the same induration of
sandstone by means of fusion, that in the argillaceous strata has
produced jasper. But oblique veins of jasper are represented as
traversing these last strata; now this is a fact which is not
conceivable in any other way, than by the injection or transfusion of
the fluid jasper among those masses of indurated strata.
All this belongs to the east side of the mountains. On the west, again,
we find the same species of strata; only these are not changed to such a
degree as to lose their original character or construction, and thus to
be termed differently in mineralogy.
Our author then proceeds. (p. 53.)
"Nous pourrons parler plus décisivement sur les _montagnes secondaires
et tertiaires_ de l'Empire, et c'est de celles-là, de la nature, de
l'arrangement et du contenu de leurs couches, des grandes inégalités et
de la forme du continent d'Europe et d'Asie, que l'on peut tirer avec
plus de confiance quelques lumières sur les changemens arrivés aux
terres habitables. Ces deux ordres de montagnes présentent la chronique
de notre globe la plus ancienne, la moins sujette aux falsifications, et
en même-tems plus lisible que le caractère des chaînes primitives;
ce font les archives de la nature, antérieures aux lettres et aux
traditions les plus reculées, qu'il étoit réservé à notre siècle
observateur de feuiller, de commenter, et de mettre au jour, mais que
plusieurs siècles après le nôtre n'épuiseront pas.
"Dans toute l'étendue de vastes dominations Russes, aussi bien que
dans l'Europe entière, les observateurs attentifs ont remarqué
que généralement la band schisteuse des grandes chaînes se trouve
immédiatement recouverte ou cottée par la _bande calcaire_. Celle-ci
forme deux ordres de montagnes, très-différentes par la hauteur, la
situation de leurs couches, et la composition de la pierre calcaire qui
les compose; différence qui est très-évidente dans cette bande calcaire
qui forme la lisière occidentale de toute la chaîne Ouralique, et dont
le plan s'étend par tout le plat pays de la Russie. L'on observerait
la même chose à l'orient de la chaîne, et dans toute l'étendue de la
Sibérie, si les couches calcaires horizontales n'y étaient recouvertes
par les dépôts postérieures, de façon qu'il ne paraît à la surface que
les parties les plus faillantes de la bande, et si ce pays n'étoit trop
nouvellement cultivé et trop peu exploité par des fouilles et autres
opérations, que des hommes industrieux ont pratiqué dans les pays
anciennement habités. Ce que je vais exposer sur les deux ordres de
montagnes calcaires, se rapportera donc principalement à celles qui sont
à l'occident de la chaîne Ouralique.
"Ce côté de la dite chaîne consiste sur cinquante à cent verstes de
largeur, de roche calcaire solide, d'un grain uni, qui tantôt ne
contient aucune trace de productions marines, tantôt n'en conserve
que des empreintes aussi légères qu'éparses. Cette roche s'élève en
montagnes d'une hauteur très-considérable, irrégulières, rapides, et
coupées de vallons escarpés. Ses couches, généralement épaisses, ne sont
point de niveau, mais très-inclinées à l'horizon, paralleles, pour la
plupart, à la direction de la chaîne, qui est aussi ordinairement celle
de la bande schisteuse;--au lieu que du côté de l'orient les couches
calcaires sont au sens de la chaîne en direction plus ou moins
approchante de l'angle droite. L'on trouve dans ces hautes montagnes
calcaires de fréquentes grottes et cavernes très-remarquables, tant
par leur grandeur que par les belles congélations et crystallizations
stalactiques dont elles s'ornent. Quelques-unes de ces grottes ne
peuvent être attribuées qu'à quelque bouleversement des couches;
d'autres semblent devoir leur origine à l'écoulement des sources
souterraines qui ont amolli, rongé et charrié une partie de la roche qui
en étoit susceptible.
"En s'éloignant de la chaîne, on voit les couches calcaires s'aplanir
assez rapidement, prendre une position horizontale, et devenir
abondantes en toute forte de coquillages, de madrépores, et d'autres
dépouilles marines. Telles on les voit par-tout dans les vallées les
plus basses qui se trouvent aux pieds des montagnes (comme aux environs
de la rivière d'Oufa); telles aussi, elles occupent tout l'étendue de la
grande Russie, tant en collines qu'en plat pays; solides tantôt et comme
semées de productions marines; tantôt toutes composées de coquilles et
madrépores brisées, et de ce gravier calcaire qui se trouve toujours sur
les parages ou la mer abonde en pareilles productions; tantôt, enfin,
dissoutes en craie et en marines, et souvent entremêlées de couches de
gravier et de cailloux roulés."
How valuable for science to have naturalists who can distinguish
properly what they see, and describe intelligibly that which they
distinguish. In this description of the strata, from the chain of
mountains here considered as primitive, to the plains of Russia, which
are supposed to be of a tertiary formation, our naturalist presents us
with another species of strata, which he has distinguished, on the one
hand, in relation to the mountains at present in question, and on the
other, with regard to the strata in the plains, concerning which there
is at present no question at all. Now, let us see how these three things
are so connected in their nature, as to form properly the contiguous
links of the same chain.
The primary and tertiary masses are bodies perfectly disconnected;
and, without a medium by which they might be approached, they would be
considered as things differing in all respects, consequently as having
their origins of as opposite a nature as are their appearances. But the
nature and formation of those bodies are not left in this obscurity;
for, the secondary masses, which are interposed, participate so
precisely of what is truly opposite and characteristic in the primary
and tertiary masses, that it requires nothing more than to see this
distinction of things in its true light, to be persuaded, that in those
three different things we may perceive a certain gradation, which
here takes place among the works of nature, and forms three steps
distinguishable by a naturalist, although in reality nothing but the
variable measure of similar operations.
We are now to assimilate the primary and tertiary masses, which are so
extremely different, by means of the secondary masses, which is the
mean. The primary and tertiary differ in the following respects: The one
of these contains the relicts of organised bodies which are not observed
in the other. But in the species containing these distinguishable
bodies, the natural structure and position of the mass is little
affected, or not so much as to be called into doubt. This, however, is
not the case with the other; the species in which organised bodies do
not appear, is in general so indurated or consolidated in its structure,
and changed in its position, that this common origin of those masses is
by good naturalists, who have also carefully examined them, actually
denied. Now, the secondary masses may be considered, not only as
intermediate with respect to its actual place, as M. Pallas has
represented it, but as uniting together the primary and tertiary, or as
participating of the distinguishing characters of the other two. It
is homologated with the primitive mountains, in the solidity of its
substance and in the position of its strata; with the tertiary species,
again, in its containing marks of organised bodies. How far this view
of things is consistent with the theory of the earth now given, is
submitted to the consideration of the unprejudiced.
Let us see what our learned author has said farther on this subject,
(page 65).
"Je dois parler d'un ordre de montagnes très-certainement postérieur aux
couches marines, puisque celles-ci, généralement lui servent de base.
On n'a point jusqu'ici observé une suite de ces _montagnes tertiaires_,
effet des catastrophes les plus modernes de notre globe, si marquée
et si puissante, que celle qui accompagne la chaine Ouralique ou côté
occidentale fur tout la longueur. Cette suite de montagnes, pour la
plupart composées de grais, de marnes rougeâtres, entremêlées de couches
diversement mixtes, forme une chaîne par-tout séparée par une vallée
plus ou moins large de la bande de roche calcaire, dont nous avons
parlé. Sillonnée et entrecoupée de fréquens vallons, elles s'élève
souvent à plus de cent toises perpendiculaires, se répand vers les
plaines de la Russie en traînées de collines, qui séparent les rivières,
en accompagnant généralement la rive boréale ou occidentale, et dégénère
enfin en déserts sableux qui occupent de grands espaces, et s'étendent
surtout par longues bandes parallèles aux principales traces qui suivent
les cours des rivieres. La principale force de ces montagnes tertiaires
est plus près de la chaîne primitive par-tout le gouvernement
d'Orenbourg et la Permie, ou elle consiste principalement en grais, et
contient un fond inépuisable de mines de cuivre sableuses, argileuses,
et autres qui se voient ordinairement dans les couches horizontales.
Plus loin, vers la plaine, sont des suites de collines toutes marneuses,
qui abondent autant en pierres gypseuses, que les autres en minerais
cuivreux. Je n'entre pas dans le détail de celles-ci, qui indiquent
sur-tout les sources salines; mais je dois dire des premières, qui
abondent le plus et dont les plus hautes élévations des plaines, même
celle de Moscou, sont formées, qu'elles contiennent très-peu de traces
de productions marines, et jamais des amas entiers de ces corps, tels
qu'une mer reposée pendant des siècles de suite a pu les accumuler dans
les bancs calcaires. Rien, au contraire, de plus abondant dans ces
montagnes de grais stratifié sur l'ancien plan calcaire, que des troncs
d'arbres entières et des fragmens de bois pétrifié, souvent minéralisé
par le cuivre ou le fer; des impressions de troncs de palmires, de
tiges de plantes, de roseau, et de quelques fruits étrangers; enfin des
ossemens d'animaux terrestres, si rares dans les couches calcaires. Les
bois pétrifiés se trouvent jusques dans les collines de sable de la
plaine; l'on en tire, entr'autres, des hauteurs sablonneuses aux
environs de Sysran sur la Volga, changés en queux très-fin, qui a
conservé jusqu'à la texture organique du bois, et remarquables sur-tout
par les traces très-évidentes de ces vers rongeurs qui attaquent les
vaisseaux, les pilotis et autres bois trempés dans la mer, et qui sont
proprement originaires de la mer des Indes."
This philosopher has now given us a view of what, according to the
present fashion of mineral philosophy, he has termed _montagnes
primitives, secondaires, et tertiaires_. The first consists in masses
and strata, much indurated and consolidated, and greatly displaced in
their position; but the character of which is chiefly taken from this,
that they contain not any visible mark of animal or vegetable bodies.
The second are formed in a great measure of marine productions, are
often no less consolidated than those of the first class, and frequently
no less changed in their natural shape and situation.
The third again have for character, according to this learned theorist,
the containing of those organised bodies which are proper to the earth,
instead of those which in the second class had belonged to the sea;
in other respects, surely there is no essential difference. It is not
pretended that these tertiary strata had any other origin, than that of
having been deposited in water; it is not so much as suspected, that
this water had been any other than that of the sea; the few marine
bodies which M. Pallas here acknowledges, goes at least to prove this
fact: and with regard to the mineral operations which had been employed
in consolidating those water formed strata, it is impossible not to be
convinced that every effect visible in the other two are here also to be
perceived.
From this view of mineral bodies, taken from the extensive observations
of the Russian dominions, and from the suppositions of geologists in
relation to those appearances, we should be led to conclude that the
globe of this earth had been originally nothing but an ocean, a world
containing neither plant nor animal to live, to grow and propagate its
species. In following a system founded on those appearances, we must
next suppose, that to the sterile unorganised world there had succeeded
an ocean stored with fish of every species. Here it would be proper to
inquire what sustained those aquatic animals; for, in such a system as
this, there is no provision made for continuing the life even of the
individuals, far less of feeding the species while, in an almost
infinite succession of individuals, they should form a continent of land
almost composed of their _exuviae_.
If fish can be fed upon water and stone; if siliceous bodies can, by
the digesting powers of animals, be converted into argillaceous and
calcareous earths; and if inflammable matter can be prepared without the
intervention of vegetable bodies, we might erect a system in which this
should be the natural order of things. But to form a system in direct
opposition to every order of nature that we know, merely because we may
suppose another order of things different from the laws of nature which
we observe, would be as inconsistent with the rules of reasoning in
science, by which the speculations of philosophy are directed, as it
would be contrary to common sense, by which the affairs of mankind are
conducted.
Still, however, to pursue our visionary system, after a continent had
been formed from the relicts of those animals, living, growing, and
propagating, during an indefinite series of ages, plants at last are
formed; and, what is no less wonderful, those animals which had formed
the earth then disappear; but, in compensation, we are to suppose, I
presume, that terrestrial animals began. Let us now reason from those
facts, without either constraining nature, which we know, or forming
visionary systems, with regard to things which are unknown. It would
appear, that at one period of time, or in one place, the matter of the
globe may be deposited, in strata, without containing any organised
bodies; at another time, or in another place, much animal matter may be
deposited in strata, without any vegetable substance there appearing;
but at another period, or at another time, strata may be formed with
much vegetable matter, while there is hardly to be observed any animal
body. What then are we to conclude upon the whole? That nature, forming
strata, is subject to vicissitudes; and that it is not always the same
regular operation with respect to the materials, although always forming
strata upon the same principles. Consequently, upon the same spot in
the sea, different materials may be accumulated at different periods of
time, and, conversely, the same or similar materials may be collected in
different places at the same time. Nothing more follows strictly from
the facts on which we now are reasoning; and this is a conclusion which
will be verified by every appearance, so far as I know.
Of this I am certain, that in a very little space of this country, in
many places, such a course of things is to be perceived. Nothing so
common as to find alternated, over and over again, beds of sand-stone
without animal bodies, beds of coal and schistus abounding with
vegetable bodies, beds of lime-stone formed of shells and corals, and
beds or particular strata of iron-stone containing sometimes vegetable
sometimes animal bodies, or both. Here, indeed, the strata are most
commonly inclined; it is seldom they are horizontal; consequently, as
across the whole country, all the strata come up to the day, and may be
seen in the beds of our rivers, we have an opportunity of observing that
great variety which is in nature, and which we are not able to explain.
This only is certain, from what we see, that there is nothing formed
in one epoch of nature, but what has been repeated in another, however
dissimilar may be the operations which had intervened between those
several epochs.
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
masses,--operations which may be formed in various degrees, even in the
different parts of the same mass. 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 constitute 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 mêmes dépôts sableux et souvent limoneux, gisent les restes
des grands animaux de l'Inde: ces ossemens d'éléphans, de rhinocéros, de
buffles monstrueux, dont on déterre tous les jours un si grand nombre,
et qui font l'admiration des curieux. En Sibérie, où l'on à découvert le
long de presque toutes les rivières ces restes d'animaux étrangers,
et l'ivoire même bien conservé en si grande abondance, qu'il forme un
article de commerce, en Sibérie, dis je, c'est aussi la couche la plus
moderne de limon sablonneux qui leur sert de sépulture, et nulle part
ces monumens étrangers sont si frequens, qu'aux endroits où la grande
chaine, qui domine surtout la frontière méridionale de la Sibérie, offre
quelque dépression, quelque ouverture considérable.
"Ces grands ossemens, tantôt épars tantôt entassés par squelettes,
et même par hécatombes, considérée dans leurs sites naturels, m'ont
sur-tout convaincu de la réalité d'un déluge arrivé 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-même, tout ce qui peut
y servir de preuve à cet évènement mémorable[24]. Une infinité de ces
ossemens couchés dans des lits mêlés de petites tellines calcinées, d'os
de poissons, de glossopètres, de bois chargés d'ocre, etc. prouve déjà
qu'ils ont été transportés par des inondations. Mais la carcasse d'un
rhinocéros, trouvé avec sa peau entière, des restes de tendons, de
ligamens, et de cartilages, dans les terres glacées des bords du
Viloûi, dont j'ai déposé les parties les mieux conservées au cabinet de
l'Académie, forme encore une preuve convaincante que ce devait être
un mouvement d'inondation des plus violens et des plus rapides, qui
entraîna jadis ces cadavres vers nos climats glacés, avant que la
corruption eût le tems, d'en détruire les parties molles. Il seroit à
souhaiter qu'un observateur parvint aux montagnes qui occupent l'espace
entre les fleuves Indighirka et Koylma où selon le rapport des
chasseurs, de semblables carcasses d'éléphans et d'autres animaux
gigantesques encore revêtues de leurs peaux, ont été remarquées à
plusieurs reprises."
[Note 24: Voyez le Mémoire, imprimé dans le XVII. volume des nouveaux
Commentaires de l'Académie Imperiale de Petersbourgh.]
The question here turns upon this, Are the sea shells 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 illustrated. 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
constitution 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 masses 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 associated 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 constitution 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 mass, which, from an atmospheric
situation, is now supposed to be lower than the surface of the sea.
Such a compound mass might be again resuscitated, or restored with the
new superincumbent strata, consolidated in their texture and inclined in
their position. In that case, the inferior mass 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
mass, and the marks of its original formation more and more obliterated.
If, in examining our land, we shall find a mass 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 mass, 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 masses 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 masses of our land, those parts which
have been erroneously considered as primitive in the constitution 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 masses, of marine origin,
superincumbent 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 analogous 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 espèce de _montagne_ très commune, et que j'avois souvent
examinée qui dessilla mes yeux. La pierre qui la compose est de
la classe appellée _schiste_; son caractère générique est d'être
_feuilletée_; 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'idée vague de dépôts des eaux. Mais il y a des masses dont la
composition est plutôt par fibres que par feuillets, et dont le moëllon
ressemble aux copeaux de bois d'un chantier. Le plus souvent aussi les
feuillets sont situés en toute suite de sens dans une même _montagne_,
et quelquefois même verticalement, Enfin il s'en trouve de si tortillés,
qu'il est impossible de les regarder comme des dépôts de l'eau.
"Ce fut donc cette espèce de montagne qui me persuada la première
que toutes les montagnes n'avoient pas une même origine. Le lieu où
j'abjurai mon erreur, étoit un de ces grands _chantiers_ pétrifiés, qui,
par la variété du tortillement, et des zig-zags des fibres du moëllon
qui le composoit, attira singulièrement mon attention. C'étoit un sort
grand talus qui venoit d'une face escarpée; j'y montai pour m'approcher
du rocher, et je remarquai, avec étonnement, des multitudes de paquets
enchevêtrés les uns dans les autres, sans ordre ni direction fixe; les
uns presqu'en rouleaux; les autres en zig-zag; et même ce qui, séparé de
la montagne, eût peu être pris pour des _couches_, le trouvoit incliné
de toute manière dans cette même face de rocher. _Non_, me dis-je alors
à moi-même; _non, l'eau n'a pu faire cette montagne.... Ni celle-là
donc_, ajoutai-je en regardant ailleurs.... _Et pourquoi mieux celle-là?
Pourquoi toutes les montagnes devroient-elles être le produit des eaux,
seulement parce qu'il y en a quelques-unes qui annoncent cette origine_?
En effet, puis qu'on n'a songé aux eaux, comme cause des montagnes,
que par les preuves évidentes que quelques-unes offroient de cette
formation; pourquoi étendre cette conséquence à toutes, s'il y en
a beaucoup qui manquent de ces caractères? C'est comme le dit Mr.
d'Alembert, qu'on généralise ses premières 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 persuadés que la mer n'avoit pas fait
toutes les _montagnes_, nous entreprîmes de découvrir les caractères
distinctifs de celles qui lui devoient leur origine; et s'il étoit, par
exemple, des matières qui leur fussent propres. Mais nous y trouvâmes
les mêmes difficultés qu'on rencontre dans tout ce qu'on veut classer
dans la nature. On peut bien distinguer entr'elles les choses qui
ont fortement l'empreinte de leur classe; mais les confins échappent
toujours.
"C'est là, pour le dire en passant, ce qui a pu conduire quelques
philosophes à imaginer cette _chaîne des êtres_ où ils supposent,
que, de la pierre à l'homme et plus haut, les nuances sont réellement
imperceptibles. Comme si, quoique les limites soyent cachées à nos sens,
notre intelligence ne nous disoit pas, qu'il y a un _saut_, une distance
même infinie, entre le plus petit degré d'organization _propageante_,
et la matière unie par la simple cohésion: entre le plus petit degré de
_sensibilité_, et la matière insensible: entre la plus petite capacité
d'observer et de transmettre ses observations, et l'instinct constamment
le même dans l'espèce. Toutes ces différences tranchées existent dans la
nature; mais notre incapacité de rien connoître à fond, et la necessité
où nous sommes de juger de tout sur des apparences, nous fait perdre
presque toutes les limites, parce que sur ces bords, la plupart des
phénomènes sont équivoques. Ainsi la plante nous paroît se rapprocher de
la pierre, mais n'en approche jamais réellement.
"On éprouve la même difficulté à classer les montagnes; et quoique
depuis quelque tems plusieurs naturalistes ayent aussi observé qu'elles
n'ont pas toutes la même origine, je ne vois pas qu'on soit parvenu à
fixer des caractères infaillibles, pour les placer sûrement toutes dans
leurs classes particulières.
"Après avoir examiné attentivement cet objet, d'après les phénomènes que
j'ai moi-même observés, et ce que j'ai appris par les observations des
autres; j'ai vu que c'étoit là un champ très vaste, quand on vouloit
l'embrasser en entier, et trop vaste pour moi, qui n'étoit pas libre d'y
consacrer tout le tems qu'il exige. Je me suis donc replié sur mon objet
principal, savoir _la cause qui a laissé des dépouilles marines dans nos
continens_, et l'examen des hypothèses sur cette matière.
"Les phénomènes ainsi limités, se réduisent à ceci: qu'il y a dans nos
continens des montagnes visiblement formées par des _dépôts successifs
de la mer_ et a l'égard des quelles il n'y a besoin de rien imaginer, si
ce n'est la manière dont elles en sont sorties: qu'il y en a d'autres au
contraire, qui ne portent aucun des caractères de cette cause, et qui,
si elles ont été produites dans la _mer_, doivent être l'effet de toute
autre cause que de simples dépôts successifs, et avoir même précédé
l'existence des animaux marins. J'abandonne donc les classes confuses
où ces caractères sont équivoques, jusqu'à ce qu'elles servent à fonder
quelque hypothèse; ayant assez de ces deux classes très distinctes pour
examiner d'apres elles tous les systèmes qui me sont connus.
"Là où ces deux classes de montagnes sont mêlées, on remarque que celles
qui sont formées par _couches_, et qui renferment des _corps marins_,
recouvrent souvent celles de l'autre classe, mais n'en sont jamais
recouvertes. On a donc naturellement conclu, que lors même que la _mer_
auroit en quelque part à la formation des montagnes où l'on ne reconnoît
pas son caractère, celles auxquelles elle a travaillé seule, en enlevant
des matières dans certaines parties de son fond et les déposant dans
d'autres, font au moins les dernières formées. On les a donc nommées
_secondaires_, et les autres _primitives_.
"J'adopterai la première de ces expressions; car c'est la même qui nous
étoit venu à l'esprit à mon frère, et à moi longtemps avant que nous
l'eussions vue employer; mais je substituerai celle de _primordiales à_
_primitives_ pour l'autre classe de _montagnes_, afin de ne rien décider
sur leur origine. Il est des _montagnes_, dont jusqu'à present on n'a pu
démêler la cause: voila le fait. Je ne dirai donc pas qu'elles ont
été créées 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 à
croire que notre globe ait existé de toute éternité; et lorsqu'il prit
naissance, il fallut bien que la matière qui le composa fut de quelque
nature, ou sous quelque première forme intégrante. Rien donc jusqu'ici
n'empêche d'admettre que ces _montagnes_ que je nommerai _primordiales_,
ne soient réellement _primitives_; je penche même pour cette opinion
à l'égard de quelques unes. Mais il y a une très grande variété
entr'elles; et quoiqu'elles soyent toutes également exclues de la classe
_secondaire_, elles ne sont pas toutes semblables: il y en a même un
grand nombre dont les matières ont une certaine configuration qui semble
annoncer qu'elles ayent été 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 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.
Let us now suppose that the under strata had been disordered at the
bottom of the sea, before the superincumbent bodies were deposited; it
is not to be well conceived, that the vertical strata should in that
case appear to be cut off abruptly, and present their regular edges
immediately under the uniformly deposited substances above. But, in the
case now under consideration, there appears the most uniform section
of the vertical strata, their ends go up regularly to the horizontal
deposited bodies. Now, in whatever state the vertical strata had been in
at the time of this event, we can hardly suppose that they could have
been so perfectly cut off, without any relict being left to trace that
operation. It is much more probable to suppose, that the sea had washed
away the relics of the broken and disordered strata, before those that
are now superincumbent had been begun to be deposited. But we cannot
suppose two such contrary operations in the same place, as that of
carrying away the relics of those broken strata, and the depositing of
sand and subtile earth in such a regular order. We are therefore led
to conclude, that the bottom of the sea, or surface of those erected
strata, had been in very different situations at those two periods, when
the relics of the disordered strata had been carried away, and when the
new materials had been deposited.
If this shall be admitted as a just view of the subject, it will be fair
to suppose, that the disordered strata had been raised more or less
above the surface of the ocean; that, by the effects of either rivers,
winds, or tides, the surface of the vertical strata had been washed
bare; and that this surface had been afterwards sunk below the influence
of those destructive operations, and thus placed in a situation proper
for the opposite effect, the accumulation of matter prepared and put in
motion by the destroying causes.
I will not pretend to say that this has all the evidence that should be
required, in order to constitute a physical truth, or principle from
whence we were to reason farther in our theory; but, as a simple fact,
there is more probability for the thing having happened in that manner
than in any other; and perhaps this is all that may be attained, though
not all that were to be wished on the occasion. Let us now see how
far any confirmation may be obtained from the examination of all the
attending circumstances in those operations.
I have already mentioned, that I had long observed great masses of
_debris_, or an extremely coarse species of pudding-stone, situated on
the south as well as north sides of those schistus mountains, where the
alpine strata terminate in our view, and where I had been looking for
the connection of those with the softer strata of the low country.
It has surely been such appearances as these which have often led
naturalists to see the formation of secondary and tertiary strata formed
by the simple congestion of _debris_ from the mountains, and to suppose
those masses consolidated by the operation of that very element by which
they had been torn off from one place and deposited in another. I never
before had data from whence to reason with regard to the natural history
of those masses of gravel and sand which always appeared to me in an
irregular shape, and not attended with such circumstances as might give
light into their natural history; but now I have found what I think
sufficient to explain those obscure appearances, and which at the same
time will in some respect illustrate or confirm the conjecture which
has now been formed with regard to the operations of the globe in those
regions.
In describing the vertical and horizontal strata of the Jed, no mention
has been made of a certain pudding-stone, which is interposed between
the two, lying immediately upon the one and under the other. This
puddingstone corresponds entirely to that which I had found along
the skirt of the schistus mountains upon the south side, in different
places, almost from one end to the other. It is a confused mass of
stones, gravel, and sand, with red marly earth; these are consolidated
or cemented in a considerable degree, and thus form a stratum extremely
unlike any thing which is to be found either above or below.
When we examine the stones and gravel of which it is composed, these
appear to have belonged to the vertical strata or schistus mountains.
They are in general the hard and solid parts of those indurated
strata, worn and rounded by attrition; particularly sand or marl-stone
consolidated and veined with quartz, and many fragments of quartz, all
rounded by attrition. In this pudding-stone of the Jed, I find also
rounded lumps of porphyry, but have not perceived any of granite.[32]
This however is not the case in the pudding-stone of the schistus
mountains, for, where there is granite in the neighbourhood, there is
also granite in the pudding-stone.
[Note 32: A view of this object is seen in plate 3d. It is from a
drawing taken by Mr Clerk of Eldin.]
From this it will appear, that the schistus mountains or the vertical
strata of indurated bodies had been formed, and had been wasted and worn
in the natural operations of the globe, before the horizontal strata
were begun to be deposited in those places; the gravel formed of those
indurated broken bodies worn round by attrition evince that fact. But
it also appears that the mineral operations of the globe, melting and
consolidating bodies, had been exerted upon those deposited strata above
the vertical bodies.
This appears evidently from the examination of our pudding-stone. The
vertical strata under it are much broken and injected with ferruginous
spar; and this same spar has greatly penetrated the pudding-stone above,
in which are found the various mineral appearances of that spar and iron
ore.