The fables of the creation of nature and man by various fantastic and
ridiculous means, which have, for thousands of years, found favour with
the unthinking multitudes inhabiting the earth, and which even now
are, one or other, firmly believed by the large majority of both the
Eastern and Western populations, must, ere long, gradually give way to
the truer and grander theory of Evolution, resulting from the study
of the natural sciences. Priests, monks, and other interested people,
backed up by the enormous wealth which has accumulated to the various
religious creeds during the past centuries of darkness, ignorance, and
gross credulity, will, no doubt, oppose all their tremendous forces
against the new philosophy, thus, for a while, delaying the inevitable
result. But this condition of things cannot last long. Education is
doing, and will continue to do, its work, until, at length, falsehood
and slavery will give place to truth and liberty.
In order to discover the origin of man, it is necessary to carry the
mind back to a very remote period, and observe the mode of development
of our planetary system; for, according to the theory of Evolution,
there were no starting points for particular forms in nature, the whole
universe consisting of one continuous unfolding of phenomena.
The modern theory of the mode of development of our earth, as also
of all other planets and suns, is the one known as the “Nebular
Hypothesis,” which is the prelude to the great theory of Evolution, and
which teaches us that the earth, the sun, the moon, the planets, and
all the heavenly host are the effects or results of the condensation of
a nebulous vapour, which took place many millions of years ago, after
having been diffused for an incalculable period of time throughout
the illimitable expanse of space. The cause of this nebulous vapour,
or attenuated matter, is unknown to us, and will probably ever remain
enshrouded in the profound mystery which at present envelopes it.
Beyond this limit all is mere speculation or hypothesis; and the
Agnostic philosopher and the man of science, humbly acknowledging
their complete inability to solve this mighty problem of ultimate
causation, are content to leave further speculation in this direction
to metaphysicians and poets.
During many long ages this process of condensation of the nebulous
vapour steadily continued, being controlled by the laws of gravitation
and transformation, until, at length, a number of rotating spherical
nebular masses were formed, in a state of high heat from the shock
of their recently-united atoms, which spheres gradually cooled by
radiation, consequently contracting and becoming possessed of a more
rapid rotary motion, giving off from their equatorial regions large
rings of vapour, which, in their turn, condensed and, under the
influence of the same two laws, formed separate spheres for themselves.
This is the mode by which our planetary system was formed, as taught by
Laplace and accepted by the scientists of to-day.
The earth, then, in common with other planets, may be said to have
passed from the condition of a gaseous to a highly-heated fluid mass,
and to have gradually become plastic, and moulded by revolution on its
own axis to its present shape—_i.e._, an oblate spheroid, or globe,
flatter at the poles than at the equator, with a polar diameter about
twenty-six miles shorter than the equatorial diameter. This is the
shape that all plastic bodies which rotate on their axes must assume,
as we are clearly taught by mathematics.
Assuming, then, that the earth was in a state of incandescence when it
began to take a definite form, we shall at once see that the denser
materials composing it would gravitate towards the centre, forming
a semi-plastic mass surrounded by an envelope of gases and watery
vapour. The gases would be quickly disposed of in various chemical
combinations, and the watery vapour would be condensed and deposited in
depressions on the surface of the central mass as soon as it had become
cooled sufficiently. The outer crust of this central, semi-solid mass
was soon converted, under the intense heat, into a hard, granite-like
rock, which was continually subject to sudden upheavals, resulting
partly from the violent escape of gases, and partly from water passing
through fissures on the surface to the heated interior and giving rise
to steam of great expansive power. In this manner great inequalities
of the surface were, no doubt, produced, whose rugged edges, after
the lapse of a vast period of time, were gradually softened down by
the subsequent action upon them of air and water. This first rock
formation is termed by geologists the Plutonic (from Pluto, monarch of
hell), on account of its being the result of intense heat, and not,
as is the case with all other rock formations, laid down in layers by
water. Whether the Plutonic rock forms a solid centre to our earth is
matter of uncertainty; but all are agreed that the internal heat of
our planet, whether caused by the friction of the particles of a solid
substance or by a molten fluid, is still, even in these later times,
intense. In boring through the earth’s crust, the average increase in
temperature for every fifty feet of descent, after the first hundred
feet from the surface, is one degree Fahr., which would give us, at a
depth of 125 miles, sufficient heat to melt most of the rocks. This
intense internal heat has generated, in times long gone by, enormous
forces, by which rocks of all ages have been raised and depressed,
twisted and distorted, broken and forced out of position, and forcibly
compressed, so as to eventually cause most important changes of surface
level.
The next class of rock-formation is totally different from the
Plutonic, or unstratified series, in that it is the result of the
wear and tear of the surface when acted upon by air and water, and is
laid down, in the first instance, by water, as sediment. Water, in
the forms of seas, rivers, rain, and ice, has been the chief agent
in the arrangement of all the stratified rocks, the determination
of the earth’s contour, the direction of valleys, and, in fact, the
regulation of the whole physical geography of the visible portion of
the earth. With the help of this mighty agent, so soon as the earth
had become sufficiently cool to permit condensation to take place in
its vapoury envelope, the ceaseless wear and tear of the Plutonic—and,
subsequently, of all other—rocks, which has accumulated so vast a
mass of material, commenced. Large volumes of water were gradually
deposited, without intermission, until permanent seas and rivers had
become established, and the new process of stratification, which was
henceforth destined to shape the crust of the earth and to provide the
conditions of life, commenced to operate. This action is taking place
daily in rivers and seas, as we may observe at any time. On the tops
of mountains the same action is in operation, though under different
conditions, snow and ice splitting fragments from the rocks to be borne
away as grit into the valleys by impetuous torrents and deposited
in other places. Within the Polar circles ice on a grander scale is
levelling down the land; glaciers, covering thousands of square miles,
are slowly sliding down the valleys, grinding their surfaces still
deeper—forming sands, clays, and gravels, and forcing these down to the
sea-shore; and icebergs, many miles in circumference, are carried by
currents along coasts and against cliffs like huge ploughs, completely
altering the face of the rocks beneath. This wear and tear results in
the formation of immense quantities of detritus, which is deposited in
layers at the bottom of seas and rivers, and consolidated by pressure,
being frequently assisted by lime, iron, or silica as a cement. The
coarser-textured rock has been laid down in rapidly-moving, shallow
water; and the finer-textured in still, deep water. Thus, through many
long ages—probably millions of years—the surface of the earth underwent
continual change from the constant deposition of stratified rock, each
layer of which completely buried beneath it the various life forms
of the previous period, which circumstance enables us to ascribe to
the various members of the animal and vegetable kingdoms particular
geological periods; for fossilised remains of animals and vegetables
have been unearthed in the different layers of the stratified rocks,
conclusively proving their existence on the earth at those periods.
In the Plutonic or unstratified rock-formation period there was,
of course, no life upon the earth, the conditions necessary for
such development not being present; but in the very earliest of the
stratified formations we find evidence of the dawn of marine life,
both vegetable and animal. Geologists have divided the stratified rock
into three chief divisions, the Palæozoic (ancient life), or Primary;
the Mesozoic (middle life), or Secondary; and the Kainozoic (latest
life), or Tertiary. Each of these, again, has been subdivided into
smaller sections, according to the particular kind of deposit met with,
the particular places where the best examples are to be found, or the
particular life-forms existing. The Primary, the depth of which is
unknown, is subdivided into seven periods—viz.:—
Laurentian, consisting of highly metamorphosed (that is, changed in
appearance from the original stratified rock character, owing to its
proximity to the molten Plutonic rock) limestone, containing fossil
remains of the Foraminifera, some of the first living organisms.
Huronian, consisting of less highly metamorphosed sandstone, limestone,
etc., and containing fossil remains of lowly-organised molluscs
(soft-bodied organisms).
Cambrian, consisting of slates, sandstones, and conglomerates,
and containing fossil remains of sponges, sea-weeds, star-fishes,
sea-lilies, lowly shell-fish, marine worms, and the first land plants.
Silurian, consisting of slates, limestones, etc., and containing fossil
remains of corals, chambered spiral shell-fish, crabs, sea-worms, and
bony plates and scales of a low form of fish.
Devonian, consisting of old red sandstone, shales, and coralline
limestone, and containing fossil land plants, fishes, belonging to
shark, ray, and sturgeon families, and first fossil insect.
Carboniferous, consisting of mountain limestone, coal, sandstone,
ironstone, clays, etc., and containing fossil scorpions, beetles, and
amphibians.
Permian, consisting of new red sandstone, marls, magnesian limestones,
etc., and containing fossils of true reptiles.