GEOLOGY LIES AT THE BOTTOM OF EARTHLY THINGS.
There seems to be no strong reason for doubting that every elementary
substance of which we have any knowledge was _separated_ at the first
from that crude mass called “the earth,” and which, along with “the
heaven,” God created in the beginning.
For, after that first assertion, we read of continued acts of
“separation” by an Almighty _fiat_. Thus light is separated from
darkness; waters from waters; water from earth. And by a like analogy we
may suppose that the “firmament” or atmosphere, the lower part of which
we breathe, was also eliminated in its component gases from the primitive
shapeless bulk of matter.
If we take forty-five miles as the average height of this atmosphere
above the surface of our globe, it is proportionately, like the thin rind
upon an apple, or the bloom upon a peach; and may very well have come
forth without any violence done to nature, or any waste of her resources,
from the womb of the earth.
OXYGEN is a gas universally diffused, for without a large supply of it
human beings and all the mammals, birds, and reptiles, would die. But
oxygen is not a more _simple_ element than CARBON or SILICON; and silicon
is almost as universal, for it enters largely into the composition of all
known rocks, excepting coal, limestone, and rock-salt.
Then, beside silicon and carbon, there is BORON, and many others, all of
which will combine permanently with the principal gases, and which we
may, therefore, fairly suppose did so in the beginning.
The oxygen which we breathe enters into composition with almost all known
substances. It constitutes about one-fifth of the atmosphere, perhaps
eight-ninths of the water, and helps chemically to compound all forms of
earth and rock, and all the metals save five. Now this proclaims at once
a _kindred_ element, and does not look like a substance made independent
of all the others at the first. Even _potash_ and _soda_, which were long
called “fixed alkalis,” having resisted all attempts to decompose them,
yielded at last to a galvanic process, and were found to be compound;
oxygen, in both cases, having united itself intimately with a metallic
base.
It is probable, therefore, that every substance which we can handle, or
of which we can recognize the presence by a chemical test, was as truly
a part of the chaotic Earth as was the clay or the granite. The gaseous
atmosphere or “firmament” was eliminated by an act of creation from
the torpid mass, the waters were drawn off and gathered together, the
rocks consolidated, the metals precipitated, most of the crystals were
probably perfected by galvanic operations. But there is nothing, from
the crystallized blocks of the mountains to the salt held in solution in
the sea, from the heavy rain-cloud which darkens the sky to the gossamer
films of vapour which fringe the outermost edge of our atmosphere,
which was not actually present as an existing particle when the Earth,
“_Mother_-Earth,” was made. And the EARTH, as we see, could very well
furnish all these concomitant and subsidiary elements, without being
impoverished at all. Indeed, as far as experiments and investigations
proper have gone, we have as yet only touched the _surface_ of our
globe. The deepest mine which men have ever sunk into the bowels of the
earth bears in its depth the same proportion to the earth’s radius, as
a _line_, or one-eighth of an inch, bears to the height of the monument
at London Bridge. Some of the exposed strata of rock, allowing for the
_tilting-up_ of their edges, certainly reveal a deeper sample than this;
but still, it is like the prick of a pin on the hide of a rhinoceros;
it does not even penetrate the creature’s folded hide; but of what lies
_within_ it tells us nothing.
Mr. Baily’s successful attempt at “weighing the Earth,” which, with
consummate patience and skill, he brought to a termination in his house
in Tavistock Square, has established the physical fact that this planet
is not “a hollow sphere,” as some persons had supposed, but _solid_,
probably to its very centre, and of considerable specific gravity. Here
is a mighty mass of Matter; it may be, as Dr. Whewell has argued, the
_greatest mass_ (in solid contents) in our Solar system. What do we
know of its interior construction, economy, and arrangement? Nothing,
except that all obey the _laws_ established by the Creator, whether
those of gravitation, cohesive attraction, or chemical combination. The
“statistical report” is wanting, especially in such departments as those
of the Trap and Volcanic lavas.
The amount of SALT in the ocean is a circumstance which geologists have
not, I think, sufficiently considered. This salt, if precipitated,
would, it is believed, yield a solid range of mountains equal to that
of the entire Himalaya. Now, mighty rivers run into the sea, as those
of La Plata, Amazons, Mississippi, St. Lawrence, Orinoko, and many
others; but _none of these rivers are salt_; they are enormous bodies of
fresh water. How, then, does the ocean maintain everywhere its saline
character unimpaired? not to ask, whence did so much salt come? There
is, indeed, a hill of salt in Spain, and there are mines of rock-salt
in Poland and Hungary; but the _effort_ which was made, so to speak,
when the proportion now existing in the ocean was squeezed out of the
huge terrestrial sponge, must far have exceeded that of any subsequent
addition or contribution.
The ocean itself, as _girding_ this globe, is a prodigious mass of water,
indeed. But, if we remember the size of the globe itself, as given by
its diameter, Ocean appears like a rain-pond. For, if we call its average
depth five miles—and it cannot be more than this, may be much less—such
a watery envelope would be represented in its proportion to the solid
sphere which it surrounds, by a coating of varnish of the thickness of
this paper lying on a globe which is twenty feet in diameter.
The COAL-MEASURES are also a remarkable item in the list of substances
met with in beds and ranges, and claiming to be considered as rocks—for
the coal is a _petrifaction_, perhaps a partial _crystallization_—but due
to the deposition of vegetable matter, subjected afterwards to enormous
hydrostatic pressure. We have no true estimate of their amount as yet,
for fresh mines are being continually discovered; but here seems to
consist the chief proportion of CARBON, as developed in this part of the
visible creation.
CHALK constitutes one-eighth part of the crust of this globe. The mass
of this must have been thrown up _at once_, when the atmosphere was
eliminated, and the waters separated, and the sphere became condensed
and solid. It is a “carbonate of lime” in its chemical description, and
there is abundance of the limestone-rock all over the world; but it is
very difficult to extract from this, in any quantity, the soft, friable,
slightly unctuous mineral which goes by the name of chalk (Latin, “calx”).
The METALS exist in the rocks, generally some distance down in the
earth’s interior. Their amount, in some instances, is very great indeed.
The only one which is rarely met with on our globe, and then in small
grains, is the NATIVE IRON, _i.e._ iron in its _pure_ state. This want,
however, could not have been recognized if we had not happened to find
the substance in question in those blocks of meteoric iron, and in the
small meteoric stones which have, from time to time, fallen to the
surface of the earth during atmospheric storms, and, probably, owing to
astronomical disturbances. For, of the iron, in its mixed conditions
of different ores, we have an abundant supply. It is a singular fact,
that the _native gold_, both in pure grains or flakes, and in solid
“nuggets,” appears now to be the more prevalent form of that ponderous
and imperishable substance. The ranges of quartz-rock in many chains of
mountains are certainly thickly sown with seeds and nodules of fine gold.
I may mention here, as an interesting circumstance to mineralogists and
collectors of fossil pebbles, that the “native iron,” which is so scarce
on the surface of the ground, is met with, from time to time, along with
_manganese_, in the heart of siliceous pebbles. But I have never seen it
where there is not the presence of some animal organism.
Now all these _solids_, gold, iron, chalk, coal, salt—and I select
incongruous items on purpose—are as truly portions of the earth’s mass
as are the granite and slate, the sandstones and clays. And _so are
also_ the flowing waters and the suspended clouds; and _so are also_ the
component elements of these—oxygen, hydrogen, and the rest. It is, all
of it, MATTER; it all obeys the law of gravitation, and it needs just as
much to be taken into account, in a geological scheme or system, as the
upheaving of granite rocks, the flux of lavas, or the icthyolite beds
amidst the semi-crystalline ranges of the Old Red Sandstone formation.
Consequently I have found, as has partly I trust been shown in the
preceding pages, that even to handle and pronounce upon a pebble, such
an one as we can pick up on the sea-shore any summer’s day, _all these
elements_ must be taken into the account.
In a “moss-agate,” for instance, I discover—
_First._ A sandy cuticle, which we will rub off, as it is like the dust
on your drawing-room table, a real thing, but out of place.
_Secondly._ Siliceous matter.
_Thirdly._ A purer form of this in chalcedony.
_Fourthly._ The “moss,” which is a metal proper, tinged by _oxidation_.
[N.B. Here is oxygen inside a pebble!]
_Fifthly._ The whole or a part of some extinct animal’s petrified
structure.
_Sixthly._ One thing more, _sometimes_ a drop of water.
_Seventhly and lastly._ Air, permeating the stone in fine pores and
channels, one of the largest of which was in some cases a breathing-hole
used by the zoophyte before he drew his last gasp.
Who shall therefore say that a PEBBLE from the sea-shore has nothing
remarkable in it or about it, merely because the passing schoolboy can
pick it up if he pleases, and, without looking at it for a moment, can
fling it at the head of a gull, or dash it to atoms against a larger
stone? It is a microcosm in itself; and if it lead us on to further
inquiry and patient thought, it will amply repay our trouble, though we
_have_ loitered away a summer morn or an autumn evening among the Pebbles
of the Beach.