Investigation of the Natural Operations employed in the Production of
Land above the Surface of the Sea.
We seek to know that operation by means of which masses of loose
materials, collected at the bottom of the sea, were raised above its
surface, and transformed into solid land.
We have found, that there is not in this globe (as a planet revolving
in the solar system) any power or motion adapted to the purpose now in
view; nor, were there such a power, could a mass of simply collected
materials have continued any considerable time to resist the waves and
currents natural to the sea, but must have been quickly carried away,
and again deposited at the bottom of the ocean. But we have found, that
there had been operations, natural to the bowels of this earth; by which
those loose and unconnected materials have been cemented together, and
consolidated into masses of great strength and hardness; those bodies
are thus enabled to resist the force of waves and currents, and to
preserve themselves, for a sufficient time, in their proper shape and
place, as land above the general surface of the ocean.
We now desire to know, how far those internal operations of the globe,
by which solidity and stability are procured to the beds of loose
materials, may have been also employed in raising up a continent of
land, to remain above the surface of the sea.
There is nothing so proper for the erection of land above the level of
the ocean, as an expansive power of sufficient force, applied directly
under materials in the bottom of the sea, under a mass that is proper
for the formation of land when thus erected. The question is not, how
such a power may be procured; such a power has probably been employed.
If, therefore, such a power should be consistent with that which we
found had actually been employed in preparing the erected mass; or,
if such a power is to be reasonably concluded as accompanying those
operations which we have found natural to the globe, and situated in the
very place where this expansive power appears to be required, we should
thus be led to perceive, in the natural operations of the globe, a power
as efficacious for the elevation of what had been at the bottom of the
sea into the place of land, as it is perfect for the preparation of
those materials to serve the purpose of their elevation.
In opposition to this conclusion, it will not be allowed to allege; that
we are ignorant how such a power might be exerted under the bottom of
the ocean; for, the present question is not, what had been the cause of
heat, which has appeared to have been produced in that place, but if
this power of heat, which has certainly been exerted at the bottom of
the ocean for consolidating strata, had been employed also for another
purpose, that is, for raising those strata into the place of land.
We may, perhaps, account for the elevation of land, by the same cause
with that of the consolidation of strata, already investigated, without
explaining the means employed by nature in procuring the power of heat,
or showing from what general source of action this particular power had
been derived; but, by finding in subterranean heat a cause for any other
change, besides the consolidation of porous or incoherent bodies, we
shall generalise a fact, or extend our knowledge in the explanation of
natural appearances.
The power of heat for the expansion of bodies, is, so far as we know,
unlimited; but, by the expansion of bodies placed under the strata at
the bottom of the sea, the elevation of those strata may be effected;
and the question now to be resolved regards the actual exertion of
this power of expansion. How far it is to be concluded as having been
employed in the production of this earth above the level of the sea.
Before attempting to resolve that question, it may be proper to observe,
there has been exerted an extreme degree of heat below the strata formed
at the bottom of the sea; and this is precisely the action of a power
required for the elevation of those heated bodies into a higher place.
Therefore, if there is no other way in which we may conceive this event
to have been brought about, consistent with the present state of things,
or what actually appears, we shall have a right to conclude, that such
had been the order of procedure in natural things, and that the
strata formed at the bottom of the sea had been elevated, as well as
consolidated, by means of subterraneous heat.
The consolidation of strata by means of fusion or the power of heat, has
been concluded from the examination of nature, and from finding, that
the present state of things is inconsistent with any other supposition.
Now, again, we are considering the only power that may be conceived as
capable of elevating strata from the bottom of the sea, and placing such
a mass above the surface of the water. It is a truth unquestionable,
that what had been originally at the bottom of the sea, is at present
the highest of our land. In explaining this appearance, therefore, no
other alternative is left, but either to suppose strata elevated by the
power of heat above the level of the present sea, or the surface of the
ocean reduced many miles below the height at which it had subsisted
during the collection and induration of the land which we inhabit.
Now, if, on the one hand, we are to suppose no general power of
subterraneous fire or heat, we leave to our theory no means for the
retreat of the sea, or the lowering of its surface; if, on the other
hand, we are to allow the general power of subterraneous heat, we cannot
have much difficulty in supposing, either the surface of the sea to have
subsided, or the bottom of the ocean, in certain parts, to have been
raised by a subterranean power above the level of its surface, according
as appearances shall be found to require the one or other of those
conclusions. Here, therefore, we are again remitted to the history of
nature, in order to find matter of fact by which this question may be
properly decided.
If the present land had been discovered by the subsiding of the waters,
there has not been a former land, from whence materials had been
procured for the construction of the present, when at the bottom of the
sea; for, there is no vestige remaining of that land, the whole land of
the present earth having been formed evidently at the bottom of the sea.
Neither could the natural productions of the sea have been accumulated,
in the shape in which we now find them, on the surface of this earth;
for, How should the Alps and Andes have been formed within the sea
from the natural productions of the water? Consequently, this is a
supposition inconsistent with every natural appearance.
The supposition, therefore, of the subsidence of the former ocean,
for the purpose of discovering the present land, is beset with more
difficulty than the simple erection of the bottom of the former ocean;
for, _first_, There is a place to provide for the retirement of the
waters of the ocean; and, _2dly_, There is required a work of equal
magnitude; this is, the swallowing up of that former continent, which
had procured the materials of the present land.
On the one hand, the subsiding of the surface of the ocean would but
make the former land appear the higher; and, on the other, the sinking
the body of the former land into the solid globe, so as to swallow up
the greater part of the ocean after it, if not a natural impossibility,
would be at least a superfluous exertion of the power of nature. Such an
operation as this would discover as little wisdom in the end elected, as
in the means appropriated to that end; for, if the land be not wasted
and worn away in the natural operations of the globe, Why make such a
convulsion in the world in order to renew the land? If, again, the land
naturally decays, Why employ so extraordinary a power, in order to hide
a former continent of land, and puzzle man?
Let us now consider how far the other proposition, of strata being
elevated by the power of heat above the level of the sea, may be
confirmed from the examination of natural appearances.
The strata formed at the bottom of the ocean are necessarily horizontal
in their position, or nearly so, and continuous in their horizontal
direction or extent. They may change, and gradually assume the nature of
each other, so far as concerns the materials of which they are formed;
but there cannot be any sudden change, fracture, or displacement,
naturally in the body of a stratum. But, if these strata are cemented by
the heat of fusion, and erected with an expansive power acting below,
we may expect to find every species of fracture, dislocation, and
contortion, in those bodies, and every degree of departure from a
horizontal towards a vertical position.
The strata of the globe are actually found in every possible position:
For, from horizontal, they are frequently found vertical; from
continuous, they are broken and separated in every possible direction;
and, from a plane, they are bent and doubled. It is impossible that they
could have originally been formed, by the known laws of nature, in their
present state and position; and the power that has been necessarily
required for their change, has not been inferior to that which might
have been required for their elevation from the place in which they had
been formed.
In this cafe, natural appearances are not anomalous. They are, indeed,
infinitely various, as they ought to be, according to the rule; but all
those varieties in appearances conspire to prove one general truth, viz.
That all which we see had been originally composed according to certain
principles, established in the constitution of the terraqueous globe;
and that those regular compositions had been afterwards greatly changed
by the operations of another power, which had introduced apparent
confusion among things first formed in order and by rule.
It is concerning the operation of this second power that we are now
inquiring; and here the apparent irregularity and disorder of the
mineral regions are as instructive, with regard to what had been
transacted in a former period of time, as the order and regularity of
those same regions are conclusive, in relation to the place in which a
former state of things had produced that which, in its changed state, we
now perceive.
We are now to conclude, that the land on which we dwell had been
elevated from a lower situation by the same agent which had been
employed in consolidating the strata, in giving them stability, and
preparing them for the purpose of the living world. This agent is matter
actuated by extreme heat, and expanded with amazing force.
If this has been the case, it will be reasonable to expect, that some of
the expanded matter might be found condensed in the bodies which have
been heated by that igneous vapour; and that matter, foreign to the
strata, may have been thus introduced into the fractures and separations
of those indurated masses.
We have but to open our eyes to be convinced of this truth. Look into
the sources of our mineral treasures; ask the miner, from whence has
come the metal into his vein? Not from the earth or air above,--not from
the strata which the vein traverses; these do not contain one atom of
the minerals now considered. There is but one place from whence these
minerals may have come; this is the bowels of the earth, the place of
power and expansion, the place from whence must have proceeded that
intense heat by which loose materials have been consolidated into rocks,
as well as that enormous force by which the regular strata have been
broken and displaced.
Our attention is here peculiarly called upon, where we have the
opportunity of examining those mineral bodies, which have immediately
proceeded from the unknown region, that place of power and energy which
we want to explore; for, if such is the system of the earth, that
materials are first deposited at the bottom of the ocean, there to be
prepared in a certain manner, in order to acquire solidity, and then to
be elevated into the proper place of land, these mineral veins, which
contain matter absolutely foreign to the surface of the earth, afford
the most authentic information with regard to the operations which we
want to understand. It is these veins which we are to consider as,
in some measure, the continuation of that mineral region, which lies
necessarily out of all possible reach of our examination. It is,
therefore, peculiarly interesting to know the state in which things
are to be found in this place, which may be considered as intermediate
between the solid land, upon the one hand, and the unknown regions of
the earth, upon the other.
We are now to examine those mineral veins; and these may be considered,
first, in relation to their form, independent of their substance or
particular contents; and, secondly, in relation to the contained bodies,
independent of their form.
In examining consolidated strata, we remarked veins and cutters as a
proof of the means by which those bodies had been consolidated. In that
case, the formation of these veins is a regulated process, determined
by the degree of fusion, and the circumstances of condensation or
refrigeration. In respect of these, the mineral veins now to be examined
are anomalous. They are; but we know not why or how. We see the effect;
but, in that effect, we do not see the cause. We can say, negatively,
that the cause of mineral veins is not that by which the veins and
fissures of consolidated strata have been formed; consequently, that
it is not the measured contraction and regulated condensation of the
consolidated land which has formed those general mineral veins; however,
veins, similar in many respects, have been formed by the cooperation of
this cause.
Having thus taken a view of the evident distinction between the veins or
contractions that are particular to the consolidated body in which they
are found, and those more general veins which are not limited to that
cause, we may now consider what is general in the subject, or what is
universal in these effects of which we wish to investigate the cause.
The event of highest generalization or universality, in the form of
those mineral veins, is fracture and dislocation. It is not, like that
of the veins of strata, simple separation and measured contraction; it
is violent fracture and unlimited dislocation. In the one case, the
forming cause is in the body which is separated; for, after the body had
been actuated by heat, it is by the reaction of the proper matter of the
body, that the chasm which constitutes the vein is formed. In the other
case, again, the cause is extrinsic in relation to the body in which the
chasm is formed. There has been the most violent fracture and divulsion;
but the cause is still to seek; and it appears not in the vein; for it
is not every fracture and dislocation of the solid body of our earth, in
which minerals, or the proper substances of mineral veins, are found.
We are now examining matter of fact, real effects, from whence we would
investigate the nature of certain events which do not now appear. Of
these, two kinds occur; one which has relation to the hardness and
solidity, or the natural constitution of the body; the other, to its
shape or local situation. The first has been already considered; the
last is now the subject of inquiry.
But, in examining those natural appearances, we find two different kinds
of veins; the one necessarily connected with the consolidating cause;
the other with that cause of which we now particularly inquire. For,
in those great mineral veins, violent fracture and dislocation is the
principle; but there is no other principle upon which strata, or masses
formed at the bottom of the sea, can be placed at a height above its
surface. Hence, in those two different operations, of forming mineral
veins, and erecting strata from a lower to a higher place, the principle
is the same; for, neither can be done without violent fracture and
dislocation.
We now only want to know, how far it is by the same power, as well as
upon the same principle, that these two operations have been made.
An expansive force, acting from below, is the power most proper for
erecting masses; but whether it is a power of the same nature with that
which has been employed in forming mineral veins, will best appear in
knowing the nature of their contents. These, therefore, may be now
considered.
Every species of fracture, and every degree of dislocation and
contortion, may be perceived in the form of mineral veins; and there is
no other general principle to be observed in examining their form. But,
in examining their contents, some other principle may appear, so far as,
to the dislocating power or force, there may be superadded matter, by
which something in relation to the nature of the power may be known.
If, for example, a tree or a rock shall be found simply split asunder,
although there be no doubt with regard to some power having been applied
in order to produce the effect, yet we are left merely to conjecture at
the power. But when wedges of wood or iron, or frozen water, should be
found lodged in the cleft, we might be enabled, from this appearance, to
form a certain judgment with regard to the nature of the power which
had been applied. This is the case with mineral veins. We find them
containing matter, which indicates a cause; and every information in
this case is interesting to the theory.
The substances contained in mineral veins are precisely the same with
those which, in the former section, we have considered as being made
instrumental in the consolidation of strata; and they are found mixed
and concreted in every manner possible.
But, besides this evidence for the exertion of extreme heat, in that
process by which those veins were filled, there is another important
observation to be gathered from the inspection of this subject. There
appears to have been a great mechanical power employed in the filling of
these veins, as well as that necessarily required in making the first
fracture and divulsion.
This appears from the order of the contents, or filling of these veins,
which is a thing often observed to be various and successive. But what
it is chiefly now in view to illustrate, is that immense force which is
manifested in the fracture and dispersion of the solid contents which
had formerly filled those veins. Here we find fragments of rock and spar
floating in the body of a vein filled with metallic substances; there,
again, we see the various fragments of metallic masses floating in the
sparry and siliceous contents.
One thing is demonstrable from the inspection of the veins and their
contents; this is, the successive irruptions of those fluid substances
breaking the solid bodies which they meet, and floating those fragments
of the broken bodies in the vein. It is very common to see three
successive series of those operations; and all this may be perceived in
a small fragment of stone, which a man of science may examine in his
closet, often better than descending to the mine, where all the examples
are found on an enlarged scale.
Let us now consider what power would be required to force up, from the
most unfathomable depth of the ocean, to the Andes or the Alps, a column
of fluid metal and of stone. This power cannot be much less than that
required to elevate the highest land upon the globe. Whether, therefore,
we shall consider the general veins as having been filled by mineral
steams, or by fluid minerals, an elevating power of immense force is
still required, in order to form as well as fill those veins. But such a
power acting under the consolidated masses at the bottom of the sea, is
the only natural means for making those masses land.
If such have been the operations that are necessary for the production
of this land; and if these operations are natural to the globe of this
earth, as being the effect of wisdom in its contrivance, we shall
have reason to look for the actual manifestation of this truth in the
phaenomena of nature, or those appearances which more immediately
discover the actual cause in the perceived effect.
To see the evidence of marble, a body that is solid, having been formed
of loose materials collected at the bottom of the sea, is not always
easy, although it may be made abundantly plain; and to be convinced that
this calcareous stone, which calcines so easily in our fires, should
have been brought into fusion by subterraneous heat, without suffering
calcination, must require a chain of reasoning which every one is not
able to attain[13]. But when fire bursts forth from the bottom of the
sea, and when the land is heaved up and down, so as to demolish cities
in an instant, and split asunder rocks and solid mountains, there
is nobody but must see in this a power, which may be sufficient to
accomplish every view of nature in erecting land, as it is situated in
the place most advantageous for that purpose.
[Note 13: Mr le Chevalier de Dolomieu, in considering the different
effects of heat, has made the following observation; Journal de
Physique, Mai 1792.
"Je dis _le feu tel que nous l'employons_ pour distinguer le feu naturel
des volcans, du feu de nos fourneaux et de celui de nos chalumeaux. Nous
sommes obligés de donner une grande activité à son action pour suppléer
et au volume qui ne seroit pas à notre disposition et au tems que nous
sommes forcés de ménager, et cette manière d'appliquer une chaleur
très-active, communique le mouvement et le désordre jusques dans les
molécules constituantes. Agrégation et composition, tout est troublé.
Dans les volcans la grand masse du feu supplée à son intensité, le
tems remplace son activité, de manière qu'il tourmente moins les corps
fournis à son action; il ménage leur composition en relâchant leur
agrégation, et les pierres qui eut été rendues fluides par l'embrasement
volcanique peuvent reprendre leur état primitif; la plupart des
substances qu'un feu plus actif auroit expulsées y restent encore. Voilà
pourquoi les laves ressemblent tellement aux pierres naturelles des
espèces analogues, qu'elles ne peuvent en être distinguées; voilà
également pourquoi les verres volcaniques eux-même renferment encore des
substances élastiques qui les font boursoufler lorsque nous les fondons
de nouveau, et pourquoi ces verres blanchissent aussi, pour lors, par
la dissipation, d'une substance grasse qui a résisté à la chaleur des
volcans, et que volatilise la chaleur par laquelle nous obtenons leur
second fusion."
No doubt, the long application of heat may produce changes in bodies
very different from those which are occasioned by the sudden application
of a more intense heat; but still there must be sufficient intensity in
that power, so as to cause fluidity, without which no chemical change
can be produced in bodies. The essential difference, however, between
the natural heat of the mineral regions, and that which we excite upon
the surface of the earth, consists in this; that nature applies heat
under circumstances which we are not able to imitate, that is, under
such compression as shall prevent the decomposition of the constituent
substances, by the separation of the more volatile from the more fixed
parts. This is a circumstance which, so far as I know, no chemist
or naturalist has hitherto considered; and it is that by which the
operations of the mineral regions must certainly be explained. Without
attending to this great principle in the mineralizing operations
of subterraneous fire, it is impossible to conceive the fusion and
concretion of those various bodies, which we examine when brought up to
the surface of the earth.]
The only question, therefore, which it concerns us to decide at present,
is, Whether those operations of extreme heat, and violent mechanic
force, be only in the system as a matter of accident; or if, on the
contrary, they are operations natural to the globe, and necessary in the
production of such land as this which we inhabit? The answer to this is
plain: These operations of the globe remain at present with undiminished
activity, or in the fullness of their power.
A stream of melted lava flows from the sides of Mount Aetna. Here is a
column of weighty matter raised from a great depth below, to an immense
height above, the level of the sea, and rocks of an enormous size
are projected from its orifice some miles into the air. Every one
acknowledges that here is the liquefying power and expansive force of
subterranean fire, or violent heat. But, that Sicily itself had been
raised from the bottom of the ocean, and that the marble called Sicilian
Jasper, had its solidity upon the same principle with the lava, would
stumble many a naturalist to acknowledge. Nevertheless, I have in my
possession a table of this marble, from which it is demonstrable, that
this calcareous stone had flowed, and been in such a state of fusion and
fluidity as lava.
Here is a comparison formed of two mineral substances, to which it is of
the highest importance to attend. The solidity and present state of the
one of these is commonly thought to be the operation of fire; of the
other, again, it is thought to be that of water. This, however, is not
the case. The immediate state and condition of both these bodies is now
to be considered as equally the effect of fire or heat. The reason of
our forming such a different judgment with regard to these two subjects
is this; we see, in the one case, the more immediate connection of the
cause and the effect, while, in the other, we have only the effects from
whence we are in science to investigate the cause.
But, if it were necessary always to see this immediate connection, in
order to acknowledge the operation of a power which, at present, is
extinguished in the effect, we should lose the benefit of science, or
general principles, from whence particulars may be deduced, and we
should be able to reason no better than the brute. Man is made for
science; he reasons from effects to causes, and from causes to effects;
but he does not always reason without error. In reasoning, therefore,
from appearances which are particular, care must be taken how we
generalise; we should be cautious not to attribute to nature, laws which
may perhaps be only of our own invention.
The immediate question now before us is not, If the subterraneous fire,
or elevating power, which we perceive sometimes as operating with such
energy, be the consolidating cause of strata formed at the bottom of the
sea; nor, if that power be the means of making land appear above the
general surface of the water? for, though this be the end we want to
arrive at ultimately, the question at present in agitation respects the
laws of nature, or the generality of particular appearances.
Has the globe within it such an active power as fits it for the
renovation of that part of its constitution which may be subject to
decay? Are those powerful operations of fire, or subterraneous heat,
which so often have filled us with terror and astonishment, to be
considered as having always been? Are they to be concluded as proper to
every part upon the globe, and as continual in the system of this earth?
If these points in question shall be decided in the affirmative, we can
be at no loss in ascertaining the power which has consolidated strata,
nor in explaining the present situation of those bodies, which had their
origin at the bottom of the sea. This, therefore, should be the object
of our pursuit; and in order to have demonstration in a case of physical
inquiry, we must again have recourse to the book of nature.
The general tendency of heat is to produce fluidity and softness; as
that of cold is, on the contrary, to harden soft and fluid bodies. But
this softening power of heat is not uniform in its nature; it is made to
act with very different effect, according to the nature of the substance
to which it is applied. We are but limited in the art of increasing the
heat or the cold of bodies; we find, however, extreme difference in
their substances with respect to fusibility.
A fusible substance, or mineral composition in a fluid state, is emitted
from those places of the earth at which subterraneous fire and expansive
force are manifested in those eruptive operations. In examining these
emitted bodies, men of science find a character for such productions, in
generalising the substance, and understanding the natural constitution
of those bodies. It is in this manner that such a person, finding a
piece of lava in any place of the earth, says with certainty, Here is a
stone which had congealed from a melted state.
Having thus found a distinguishing character for those fused substances
called, in general, Lavas, and having the most visible marks for that
which had been actually a volcano, naturalists, in examining different
countries, have discovered the most undoubted proofs of many ancient
volcanos, which had not been before suspected. Thus, volcanos will
appear to be not a matter of accident, or as only happening in a
particular place, they are general to the globe, so far as there is
no place upon the earth that may not have an eruption of this kind;
although it is by no means necessary for every place to have had those
eruptions.
Volcanos are natural to the globe, as general operations; but we are
not to consider nature as having a burning mountain for an end in her
intention, or as a principal purpose in the general system of this
world. The end of nature in placing an internal fire or power of heat,
and a force of irresistible expansion, in the body of this earth, is to
consolidate the sediment collected at the bottom of the sea, and to form
thereof a mass of permanent land above the level of the ocean, for the
purpose of maintaining plants and animals. The power appointed for this
purpose is, as on all other occasions, where the operation is important,
and where there is any danger of a shortcoming, wisely provided
in abundance; and there are contrived means for disposing of the
redundancy. These, in the present case, are our volcanos.
A volcano is not made on purpose to frighten superstitious people
into fits of piety and devotion, nor to overwhelm devoted cities with
destruction; a volcano should be considered as a spiracle to the
subterranean furnace, in order to prevent the unnecessary elevation of
land, and fatal effects of earthquakes; and we may rest assured, that
they, in general, wisely answer the end of their intention, without
being in themselves an end, for which nature had exerted such amazing
power and excellent contrivance.
Let us take a view of the most elevated places of the earth; if the
present theory is just, it is there that we should find volcanos. But is
not this the case? There are volcanos in the Andes; and round the Alps
we find many volcanos, which are in France upon the one side, and in
Germany upon the other, as well as upon the Italian side, where Vesuvius
still continues to exhibit violent eruptions.
It is not meant to allege, that it is only upon the summit of a
continent volcanos should appear. Subterraneous fire has sometimes made
its appearance in bursting from the bottom of the sea. But, even in
this last case, land was raised from the bottom of the sea, before the
eruption made its exit into the atmosphere. It must also be evident,
that, in this case of the new island near Santorini, had the expansive
power been retained, instead of being discharged, much more land might
have been raised above the level of the ocean.
Now, the eruption of that elastic force through the bottom of the sea,
may be considered as a waste of power in the operations of the globe,
where the elevation of indurated strata is an object in the exertion of
that power; whereas, in the centre of a continent sufficiently elevated
above the level of the sea, the eruption of that fiery vapour calculated
to elevate the land, while it may occasionally destroy the habitations
of a few, provides for the security and quiet possession of the many.
In order to see the wisdom of this contrivance, let us consider the
two extreme places at which this eruption of ignited matter may be
performed. These are, on the one hand, within a continent of land, and,
on the other, at the bottom of the ocean. In the one case, the free
eruption of the expanding power should be permitted; because the purpose
for which it had been calculated to exist has been accomplished. In
the other, again, the free eruption of that powerful matter should be
repressed; because there is reserved for that power much of another
operation in that place. But, according to the wise constitution of
things, this must necessarily happen. The eruption of the fiery
vapour from volcanos on the continent or land, is interrupted only
occasionally, by the melted bodies flowing in the subterraneous
chimney; whereas, at the bottom of the ocean, the contact of the water
necessarily tends to close the orifice, by accumulating condensed matter
upon the weakest place.
If this be a just theory of the natural operations of the globe, we
shall have reason to expect, that great quantities of this melted
matter, or fusible substance, may be found in form of lava, among the
strata of the earth, where there are no visible marks of any volcano, or
burning mountain, having existed. Here, therefore, is an important point
to be determined; for, if it shall appear that much of this melted
matter, analogous to lava, has been forced to flow among the strata
which had been formed at the bottom of the sea, and now are found
forming dry land above its surface, it will be allowed, that we have
discovered the secret operations of nature concocting future land, as
well as those by which the present habitable earth had been produced
from the bottom of the abyss. Here, therefore, we shall at present rest
the argument, with endeavouring to show that such is actually the case.
It appears from Cronstedt's Mineralogy, that the rock-stone, called trap
by the Swedes, the amygdaloides and the schwarts-stein of the Germans,
are the same with the whin-stone of this country. This is also fully
confirmed by specimens from Sweden, sent me by my friend Dr Gahn.
Whatever, therefore, shall be ascertained with regard to our whin-stone,
may be so far generalized or extended to the countries of Norway,
Sweden, and Germany.
The whin-stone of Scotland is also the same with the toad-stone of
Derbyshire, which is of the amygdaloides species; it is also the same
with the flagstone of the south of Staffordshire, which is a simple
whin-stone, or perfect trap. England, therefore, must be included in
this great space of land, the mineral operations of which we explore;
and also Ireland, of which the Giant's Causeway, and many others, are
sufficient proof.
In the south of Scotland, there is a ridge of hills, which extends
from the west side of the island in Galloway to the east side in
Berwickshire, composed of granite, of schistus, and of siliceous strata.
The Grampians on the north, again, form another range of mountains of
the same kind; and between these two great fields of broken, tumbled,
and distorted strata, there lies a field of lesser hardness and
consolidation, in general; but a field in which there is a great
manifestation of subterraneous fire, and of exerted force.
The strata in this space consist, in general, of sand-stone, coal,
lime-stone or marble, iron-stone, and marl or argillaceous strata, with
strata of analogous bodies, and the various compositions of these. But
what is to the present purpose is this, that, through all this space,
there are interspersed immense quantities of whinstone; a body which is
to be distinguished as very different from lava; and now the disposition
of this whin-stone is to be considered.
Sometimes it is found in an irregular mass or mountain, as Mr Cronstedt
has properly observed; but he has also said, that this is not the case
in general. His words are: "It is oftener found in form of veins in
mountains of another kind, running commonly in a serpentine manner,
contrary or across to the direction of the rock itself."
The origin of this form, in which the trap or whin-stone appears, is
most evident to inspection, when we consider that this solid body had
been in a fluid state, and introduced, in that state, among strata,
which preserved their proper form. The strata appear to have been
broken, and the two correspondent parts of those strata are separated to
admit the flowing mass of whin-stone.
A fine example of this kind may be seen upon the south side of the
Earn, on the road to Crief. It is twenty-four yards wide, stands
perpendicular, and appears many feet above the surface of the ground. It
runs from that eastward, and would seem to be the same with that which
crosses the river Tay, in forming Campsy-lin above Stanley, as a lesser
one of the same kind does below it. I have seen it at Lednoc upon the
Ammon, where it forms a cascade in that river, about five or six
miles west of Campsy-lin. It appears to run from the Tay east through
Strathmore, so that it may be considered as having been traced for
twenty or thirty miles, and westwards to Drummond castle, perhaps much
farther.
Two small veins of the same kind, only two or three feet wide, may be
seen in the bed of the Water of Leith, traversing the horizontal strata,
the one is above St Bernard's well, the other immediately below it. But,
more particularly, in the shire of Ayr, to the north of Irvine, there
are to be seen upon the coast, between that and Scarmorly, in the space
of about twenty miles, more than twenty or thirty such dykes (as they
are called) of whin-stone. Some of them are of a great thickness; and,
in some places, there is perceived a short one, running at right angles,
and communicating with other two that run parallel.
There is in this country, and in Derbyshire[14], another regular
appearance of this stone, which Cronstedt has not mentioned. In this
case, the strata are not broken in order to have the whin-stone
introduced, they are separated, and the whin-stone is interjected in
form of strata, having various degrees of regularity, and being of
different thickness. On the south side of Edinburgh, I have seen, in
little more than the space of a mile from east to west, nine or ten
masses of whin-stone interjected among the strata. These masses of
whin-stone are from three or four to an hundred feet thick, running
parallel in planes inclined to the horizon, and forming with it an angle
of about twenty or thirty degrees, as may be seen at all times in the
hill of Salisbury Craggs.
[Note 14: See Mr Whitehurst's Theory of the Earth.]
Having thus described these masses, which have flowed by means of
heat among the strata of the globe, strata which had been formed by
subsidence at the bottom of the sea, it will now be proper to examine
the difference that subsists between these subterraneous lavas, as they
may be termed, and the analogous bodies which are proper lavas, in
having issued out of a volcano.[15]
[Note 15: The Chevalier de Dolomieu, in his accurate examination of
Aetna and the Lipari islands, has very well observed the distinction of
these two different species of lavas; but without seeming to know the
principle upon which this essential difference depends. No bias of
system, therefore, can here be supposed as perverting the Chevalier's
view, in taking those observations; and these are interesting to the
present theory, as corresponding perfectly with the facts from whence it
has been formed. It will be proper to give the account of these in his
own words.
La zéolite est très-commune dans certains laves de l'Ethna; il seroit
peut-être possible d'y en rencontrer des morceaux aussi gros que ceux
que fournit l'isle de Ferroé. Quoique cette substance semble ici
appartenir aux laves, je ne dirai cependant point que toutes les
zéolites soient volcaniques, ou unies à des matières volcaniques; celles
que l'on trouve en Allemagne sont, dit-on, dans des circonstances
différentes; mais je doit annoncer que je n'ai trouvé cette substance en
Sicile, que dans les seules laves qui évidemment ont coulé dans la mer,
et qui out été recouvertes par ses eaux. La zéolite des laves n'est
point une déjection volcanique, ni une production du feu, ni même un
matière que les laves aient enveloppée lorsqu'elles étoient fluides;
elle est le résultat d'une opération et d'une combinaison postérieure,
auxquelles les eaux de la mer ont concouru. Les laves qui n'ont pas été
submergées, n'en contiennent jamais. J'ai trouvé ces observations si
constantes, que par-tout où je rencontrois de la zéolite, j'étois sûr
de trouver d'autres preuves de submersion, et partout où je voyois des
laves recouvertes des dépôts de l'eau, j'étois sûr de trouver de la
zéolite, et un de ces faits m'a toujours indiqué l'autre. Je me suis
servi avec succès de cette observation pour diriger mes recherches, et
pour connoître l'antiquité des laves. _Minéralogie de Volcans, par
M. Faujas de Saint-Fond_. Here would appear to be the distinction of
subterraneous lava, in which zeolite and calcareous spar may be found,
and that which has flowed from a volcano, in which neither of these are
ever observed.]
There can be no doubt that these two different species of bodies have
had the same origin, and that they are composed of the same materials
nearly; but from the different circumstances Of their production, there
is formed a character to these bodies, by which, they may be perfectly
distinguished. The difference of those circumstances consists in this;
the one has been emitted to the atmosphere in its fluid state the other
only came to be exposed to the light in a long course of time, after it
had congealed under the compression of an immense load of earth, and
after certain operations, proper to the mineral regions, had been
exercised upon the indurated mass. This is the cause of the difference
between those erupted lavas, and our whin-stone, toad-stone, and the
Swedish trap, which may be termed subterraneous lava. The visible
effects of those different operations may now be mentioned.
In the erupted lavas, those substances which are subject to calcine and
vitrify in our fires, suffer similar changes, when delivered from a
compression which had rendered them fixed, though in an extremely heated
state. Thus, a lava in which there is much calcareous spar, when it
comes to be exposed to the atmosphere, or delivered from the compressing
force of its confinement, effervesces by the explosion of its fixed
air; the calcareous earth, at the same time, vitrifies with the other
substances. Hence such violent ebullition in volcanos, and hence the
emission of so much pumice-stone and ashes, which are of the same
nature.
In the body of our whin-stone, on the contrary, there is no mark of
calcination or vitrification. We frequently find in it much calcareous
spar, or the _terra calcarea aerata_, which had been in a melted state
by heat, and had been crystallized by congelation into a sparry form.
Such is the _lapis amygdaloides_, and many of our whin-stone rocks,
which contain pebbles crystallized and variously figured, both
calcareous, siliceous, and of a mixture in which both these substances
form distinct parts. The specimens of this kind, which I have from the
whin-stone or porphyry rock of the Calton-hill, exhibit every species
of mineral operation, in forming jasper, figured agate, and marble; and
they demonstrate, that this had been performed by heat or fusion.
I do not mean to say, that this demonstration is direct; it is
conditional, and proceeds upon the supposition, that the basaltic or
porphyry rock, in which those specimens are found, is a body which had
been in a melted state. Now, this is a supposition for which I have
abundance of evidence, were it required; but naturalists are now
sufficiently disposed to admit that proposition; they even draw
conclusions from this fact, which, I think, they are not sufficiently
warranted in doing; that is, from this appearance, they infer the former
existence of volcanos in those places. For my part, though I have made
the most strict examination, I never saw any vestige of such an event.
That there are, in other countries, evident marks of volcanos which
have been long extinguished, is unquestionably true; but naturalists,
imagining that there are no other marks of subterraneous fire and
fusion, except in the production of a lava, attribute to a volcano, as
a cause, these effects, which only indicate the exertion of that power
which might have been the cause of a volcano.
If the theory now given be just, a rock of marble is no less a mark
of subterraneous fire and fusion, than that of the basaltes; and the
flowing of basaltic streams among strata broken and displaced, affords
the most satisfactory evidence of those operations by which the body of
our land had been elevated above the surface of the sea; but it gives no
proof that the eruptive force of mineral vapours had been discharged in
a burning mountain. Now, this discharge is essential in the proper idea
of a volcano.
Besides this internal mark of an unerupted lava in the substance of the
stone or body of the flowing mass, there are others which belong to it
in common with all other mineral strata, consolidated by subterraneous
fire, and changed from the place of their original formation; this is,
the being broken and dislocated, and having veins of foreign matter
formed in their separations and contractions.
If these are mineral operations, proper to the lower regions of the
earth, and exerted upon bodies under immense compression, such things
will be sometimes found in the unerupted lavas, as well as in the
contiguous bodies with which they are associated. If, on the contrary,
these are operations proper to the surface of the earth, where the
dissolving power of water and air take place, and where certain
stalactical and ferruginous concretions are produced by these means;
then, in erupted lavas, we should find mineral concretions, which
concretions should be denied to bodies which had been consolidated at
the bottom of the sea; that is to say, where, without the operation of
subterraneous fire, no changes of that kind could have taken place, as
has already been observed. But in the unerupted species of lava, that
is to say, in our whin-stone, every species of mineral appearance is
occasionally to be found. Let those who have the opportunity to examine,
say, what arc to be found in proper lavas, that is, those of the erupted
kind. Sir William Hamilton informed me, when I showed him those mineral
veins and spars in our whin-stone, that he had never observed the like,
in lavas We have now formed some conclusions with regard to the nature
and production of those parts of the land of this globe which we
have had the means of examining perfectly; but; from the accounts of
travellers, and from, the specimens which are brought to us from distant
parts, we have reason to believe, that all the rest of the earth is
of the same nature with that which has been now considered. The great
masses of the earth are the same every where; and all the different
species of earths, of rocks or stone, which have as yet appeared, are to
be found in the little space of this our island.
It is true, that there are peculiar productions in the mineral kingdom
which are rare, as being found only in few places; but these things are
merely accidental in relation to the land, for they belong in property
to those parts of the mineral region which we never see. Such are, the
diamond of the east, the platina of the west, and the tin of Cornwall,
Germany, and Sumatra. Gold and silver, though found in many countries,
do not appear to be immediately necessary in the production of a
habitable country. Iron, again, is universal in the operations of the
globe, and is found often in that profusion which equals its utility.
Between these two extremes, we find all other minerals, that is to say,
here and there in moderate quantity, and apparently in some proportion
to their use. But all these substances are to be considered as the
vapours of the mineral regions, condensed occasionally in the crevices
of the land; and it is only the rocks and strata (in which those mineral
veins are found) that are now examined with regard to their original
composition, at the bottom of the sea, as well as to that, operation by
which those bodies had been indurated in their substance, and elevated
from the place in which they had been formed.
Thus, we have sufficient reason to believe, that, in knowing the
construction of the land in Europe, we know the constitution of the land
in every part of the globe. Therefore, we may proceed to form general
conclusions, from the knowledge of the mineral region, thus acquired in
studying those parts which are seen.
Having thus found, _first_, That the consolidated and indurated masses
of our strata had suffered the effects of violent heat and fusion;
_2dly_, That those strata, which had been formed in a regular manner at
the bottom of the sea, have been violently bended, broken, and removed
from their original place and situation; and, _lastly_, Having now found
the most indubitable proof, that the melting, breaking, and removing
power of subterraneous fire, has been actually exerted upon this land
which we examine, we cannot hesitate in ascribing these operations as a
cause to those effects which are exposed to our view. Now, these may be
considered as consisting in the solid state and present situation of
those stratified bodies, originally formed by subsidence in the ocean;
appearances which cannot, in reason, be ascribed to any other cause, and
which, upon this principle, are perfectly explained.
It is not meant to specify every particular in the means employed by
nature for the elevation of our land. It is sufficient to have shown,
that there is, in nature, means employed for the consolidating of
strata, formed originally of loose and incoherent materials; and that
those same means have also been employed in changing the place and
situation of those strata. But how describe an operation which man
cannot have any opportunity of perceiving? Or how imagine that, for
which, perhaps, there are not proper data to be found? We only know,
that the land is raised by a power which has for principle subterraneous
heat; but, how that land is preserved in its elevated station, is a
subject in which we have not even the means to form conjecture; at
least, we ought to be cautious how we indulge conjecture in a subject
where no means occur for trying that which is but supposition.
We now proceed, from the facts which have been properly established, to
reason with regard to the duration of this globe, or the general view of
its operations, as a living world, maintaining plants and animals.