which was covered with a deposit of mud, on which an irregular layer of
sparry stalagmite had formed by the dripping of water from the low roof,
carrying lime in solution. Beneath this crust the remains were found.
Of the animals to which the bones belonged, six were _Carnivora_, viz.
_hyaena_, _felis_, bear, wolf, fox, weasel; four _Pachydermata_, viz.
elephant, rhinoceros, hippopotamus, horse; four _Ruminantia_, viz. ox,
and three species of deer; four _Rodentia_, viz. hare, rabbit,
water-rat, mouse; five Birds, viz. raven, pigeon, lark, duck, snipe.
The bones were almost universally broken; the fragments exhibited no
marks of rolling in the water, but a few were corroded; some were worn
and polished on the convex surface; many indented, as by the canine
teeth of carnivorous animals. In the cave the peculiar excrement of
hyaenas (_album graecum_) was common; the remains of these predacious
beasts were the most abundant of all the bones; their teeth were found
in every condition, from the milk-tooth to the old worn stump; and from
the whole evidence Dr. Buckland adopted the conclusion, in which almost
every subsequent writer has acquiesced, that Kirkdale Cave was a den of
hyaenas during the period when elephants and hippopotami (not of existing
species) lived in the northern regions of the globe, and that they
dragged into it for food the bodies of animals which frequented the
vicinity.[36]
Thus in these spots we find, observes Professor Ansted, "written in no
obscure language, a portion of the early history of our island after it
had acquired its present form, while it was clothed with vegetation, and
when its plains and forests were peopled by many of the species which
still exist there; but when there also dwelt upon it large carnivorous
animals, prowling about the forests by night, and retiring by day to
these natural dens."
In our own country, and in many other parts of the world, we find
fragments of stone distributed over the surface, sometimes in the form
of enormous blocks, bearing in their fresh angles evidence that they
have been little disturbed since their disruption, but sometimes much
rubbed and worn, and broken into smaller pieces, till they form what is
known as gravel. In many cases the original rock from which these
masses have been separated does not exist in the vicinity of their
locality; and it is not till we reach a distance, often of hundreds of
miles, that we find the formation of which they are a component part.
Various causes have been suggested for the transport of these erratic
blocks, of which the most satisfactory is the agency of ice, either as
slow-moving glaciers, or as oceanic icebergs.
"The common form of a glacier," says Professor J. Forbes, "is a river of
ice filling a valley, and pouring down its mass into other valleys yet
lower. It is not a frozen ocean, but a frozen torrent. Its origin or
fountain is in the ramifications of the higher valleys and gorges, which
descend amongst the mountains perpetually snow-clad. But what gives to a
glacier its most peculiar and characteristic feature is, that it does
not belong exclusively or necessarily to the snowy region already
mentioned. The snow disappears from its surface in summer as regularly
as from that of the rocks which sustain its mass. It is the prolongation
or outlet of the winter-world above; its gelid mass is protruded into
the midst of warm and pine-clad slopes and green-sward, and sometimes
reaches even to the borders of cultivation."[37]
The glacier moves onward with a slow but steady march towards the mouth
of its valley. Its lowest stratum carries with it numerous fragments of
rock, which, pressed by the weight of the mighty mass, scratch and
indent the surfaces over which they move, and sometimes polish them.
These marks are seen on many rock-surfaces now exposed, and they are
difficult to explain on any other hypothesis than that of glacial
action.
But the alternate influence of summer and winter--the percolation of
rain into the mountain fissures, and the expansion of freezing--dislodge
great angular fragments of rock, which fall on the glacier beneath.
Slowly but surely these then ride away towards the mouth of the valley,
till they reach a point where the warmth of the climate does not permit
the ice to proceed; the blocks then are deposited as the mass melts. But
if the climate itself were elevated, or if the surface were lowered so
as to immerse the glacier in the sea, it would melt throughout its
course, and then the blocks would be found arranged in long lines or
_moraines_, such as we see now in many places.
If the glacier-valley debouch on the sea, the ice gradually projects
more and more, until the motions of the waves break off a great mass,
which floats away, carrying on its surface the accumulation of
boulders, gravel, and other _debris_ which it had acquired during its
formation. It is now an iceberg, which, carried by the southern
currents, approaches a warmer climate, melts, and deposits its cargo,
perhaps hundreds of leagues from the valley where it was shipped, and as
fresh as when its component _frusta_ were detached from the primitive
rock.
If the abundance of such erratic blocks and foreign gravel seem to
require a greater amount of glacial action than is now extant, it has
been suggested that the volcanic energy which elevated Europe may have
been succeeded by a measure of subsidence before the land attained its
present permanent condition. Hence there may have been, during the
Tertiary epoch, mountain chains of great elevation, sufficient to supply
the glaciers, which, on their subsidence, melted on the spot where they
were submerged, or floated away as icebergs on the pelagic currents,
till they grounded on the bays and inlets of other shores, which were
subsequently elevated again.
Thus a large portion of the animals which then inhabited these islands
(up to that time, perhaps, united to the continent) would be drowned,
and many species quite obliterated, a few alone remaining to connect our
present fauna with that of the submerged area, when the land rose again
to its existent state.
It would not materially augment the force of the evidence already
adduced on the question of chronology, to examine in detail the fossil
remains of South America, Australia, and New Zealand. The gigantic
Sloths[38] of the first, the gigantic Marsupials of the second, and the
gigantic Birds of the third, however interesting individually, and
especially as showing that a prevailing type governed the fauna in each
locality then as now--are all formations of the Tertiary period, and
some of them, at least, seem to have run on even into the present epoch.
Indeed, it is not quite certain that the enormous birds of New Zealand
and Madagascar are even yet extinct.
The phenomenon of raised sea-beaches is one of great interest, and seems
to be connected with the alternate elevations and depressions of the
Tertiary epoch, perhaps marking the successive steps of the upheaval of
the land. In several parts of England the coast-line exhibits one or
more shelves parallel with the existing sea-beach, and covered with
similar shingle, sand, and sea-shells. And the same phenomenon is
exhibited on a still more gigantic scale in South America. Mr.
Darwin[39] found that for a distance of at least 1,200 miles from the
Rio de la Plata to the Straits of Magellan on the eastern side, and for
a still longer distance on the west, the coast-line and the interior
have been raised to a height of not less than 100 feet in the northern
part, but as much as 400 feet in Patagonia. All this change has taken
place within a comparatively short period; for in Valparaiso, where the
effect is most considerable, modern marine deposits, with human remains,
are seen at the height of 1,300 feet above the sea.
At what exact point, geologically, the period of human history begins,
it is impossible to say. No evidence of Man's presence has occurred
older than the latest Tertiary deposits, which insensibly merge into
the Alluvial. It seems certain that human remains have been found in
chronological association with those of animals long extinct, and there
appears no reason to doubt that some species of animals, as the Irish
Deer, the Moa of New Zealand, and the Dodo of the Mauritius, have
disappeared from creation within a period of a few centuries.[40] It is
not improbable that the last of the Moho race may have lived only long
enough to grace the pages of the "Birds of Australia."
[Illustration: THE MOHO.]
It is as important as it is interesting, to observe that the same kinds
of physical operations have been, within the present epoch, and are
still, going on, as those whose results are chronicled in the rocks.
Strata of alluvium are constantly being formed on a scale which, though
it does not _suddenly_ affect the outline of coasts, and therefore
appears small, yet is great in reality.
The Ganges is estimated to pour into the Indian Ocean nearly 6,400
millions of tons of mud every year; and its delta is a triangle whose
sides are two hundred miles long. The delta of the Mississippi is of
about the same size, and it advances steadily into the Gulf of Mexico at
the rate of a mile in a century.
The accumulation of river-mud is gradually filling up the Adriatic Sea.
From the northernmost point of the Gulf of Trieste to the south of
Ravenna, there is an uninterrupted series of recent accessions of land,
more than a hundred miles in length, which, within the last twenty
centuries, have increased from two to twenty miles in breadth.
The coral-polypes are working still with great energy. Mr. Darwin
mentions two or three examples of the rate of increase, one of which
only I shall cite. In the lagoon of Keeling Atoll, a channel was dug for
the passage of a schooner built upon the island, through the reef into
the sea; in ten years afterward, when it was examined, it was found
almost choked up with living coral.
Volcanic action is busy in many parts of the earth, pouring forth clouds
of ashes and torrents of molten rock; and instances are not wanting in
which new islands have been raised from the bed of the ocean by this
means, within the sphere of history.
Slow and permanent changes of level are still being produced on the
earth's crust. The bottom of the Baltic has been, for several centuries
at least, in process of continuous elevation, the effects of which are
palpable. Many rocks formerly covered are now permanently exposed;
channels between islets, formerly used, are now closed up, and beds of
marine shells have become bare. On the other hand, the whole area of the
Pacific Polynesia seems subsiding.
Deposits are being made by waters which hold earthy substances in
solution. The principal of these is _lime_. Several remarkable examples
of this kind are quoted by Sir Charles Lyell, in one of which there is a
thickness of 200 or 300 feet of travertine of recent deposit, while in
another a solid mass thirty feet thick was deposited in about twenty
years. He also states that there are other countless places in Italy
where the constant formation of limestone may be seen, while the same
may be said of Auvergne and other volcanic districts. In the Azores,
Iceland, and elsewhere, _silica_ is deposited often to a considerable
extent. Deposits of _asphalt_ and other bituminous products occur in
other places.[41]
The floors of limestone caverns are frequently strewn with fossil bones,
which are imbedded in stalagmite, and this incrustation is still in
progress of formation. It is remarkable that in this deposit alone we
obtain the bones of Man in a fossil condition. The two creations,--the
extinct and the extant,--or rather the prochronic and the
diachronic--here unite. But there is no line of demarcation between
them; they merge insensibly into each other. The bones of Man, and even
his implements and fragments of pottery, are found mingled with the
skeletons of extinct animals in the caves of Devonshire, in those of
Brazil,[42] and in those of Franconia. In Peru, some scores of human
skeletons have been found in a bed of travertine, associated with marine
shells; the stratum itself being covered by a deep layer of vegetable
soil, forming the face of a hill crowned with large trees.
From a very interesting paper by M. Marcel de Serres, it appears
indubitable that the existing shells of the Mediterranean are even now
passing in numbers into the fossil state, and that not in quiet spots
only, but where the sea is subject to violent agitations. Specimens of
common species, "completely petrified, have been converted into
carbonate of lime at the same time that they have lost the animal matter
which they originally contained. Their hardness and solidity are greater
than those of some petrified species from tertiary formations."
"In the collection of M. Doumet, Mayor of Cette, there exists an anchor
which exhibits the same circumstances, and which is also covered with a
layer of solid calcareous matter. This contains specimens of _Pecten_,
_Cardium_, and _Ostrea_, completely petrified, and the hardness of which
is equal to that of fossil species from secondary formations. On the
surface of the deposit in which the anchor is imbedded, there are
_Anomiae_ and _Serpulae_, which were living when the anchor was got out of
the sea; these present no trace of alteration."[43]
Thus we have brought down the record to an era embraced by human
history, and even to individual experience; and we confidently ask, Is
it possible, is it imaginable, that the whole of the phenomena which
occur below the diluvial deposits can have been produced within six
days, or seventeen centuries? Let us recapitulate the principal facts.
1. The crust of the earth is composed of many layers, placed one on
another in regular order. All of these are solid, and most are of great
density and hardness. Most of them are of vast thickness, the aggregate
not being less than from seven to ten miles.
2. The earlier of these were made and consolidated before the newer were
formed; for in several cases, it is demonstrable that the latter were
made out of the _debris_ of the former. Thus the compact and hard
granite was disintegrated grain by grain; the component granules were
rolled awhile in the sea till their angles were rubbed down; they were
slowly deposited, and then consolidated in layers.
3. A similar process goes on again and again to form other strata, all
occupying long time, and all presupposing the earlier ones.[44]
4. After some strata have been formed and solidified, convulsions force
them upward, contort them, break them, split them asunder. Melted matter
is driven through the outlets, fills the veins, spreads over the
surface, settles into the hollows, cools and solidifies.
5. After the outflowing and consolidation of these volcanic streams, the
action of running water cuts them down, cleaving beds of immense depth
through their substance. Mr. Poulett Scrope, speaking of the solidified
streams of basalt, in the volcanic district of Southern France,
observes:--
"These ancient currents have since been corroded by rivers,
which have worn through a mass of 150 feet in height, and
formed a channel even in the granite rocks beneath, since
the lava first flowed into the valley. In another spot, a
bed of basalt, 160 feet high, has been cut through by a
mountain stream. The vast excavations effected by the
erosive power of currents along the valleys which feed the
Ardeche, since their invasion by lava-currents, prove that
even the most recent of these volcanic eruptions belong to
an era incalculably remote."[45]
6. A series of organic beings appears, lives, generates, dies; lives,
generates, dies; for thousands and thousands of successive generations.
Tiny polypes gradually build up gigantic masses of coral,--mountains and
reefs--microscopic foraminifera accumulate strata of calcareous sand;
still more minute infusoria--forty millions to the inch--make slates,
many yards thick, of their shells alone.
7. The species at length die out--a process which we have no data to
measure,[46] though we may reasonably conclude it very long. Sometimes
the whole existing fauna seems to have come to a sudden violent end; at
others, the species die out one by one. In the former case suddenly, in
the latter progressively, new creatures supply the place of the old. Not
only do species change; the very genera change, and change again. Forms
of beings, strange beings, beings of uncouth shape, of mighty ferocity
and power, of gigantic dimensions, come in, run their specific race,
propagate their kinds generation after generation,--and at length die
out and disappear; to be replaced by other species, each approaching
nearer and nearer to familiar forms.
8. Though these early creatures were unparalleled by anything existing
now, yet they were animals of like structure and economy essentially. We
can determine their analogies and affinities; appoint them their proper
places in the orderly plan of nature, and show how beautifully they
fill hiatuses therein. They had shells, crusts, plates, bones, horns,
teeth, exactly corresponding in structure and function to those of
recent animals. In some cases we find the young with its milk-teeth by
the side of its dam with well-worn grinders. The fossil excrement is
seen not only dropped, but even in the alimentary canal. Bones bear the
marks of gnawing teeth that dragged them and cracked them, and fed upon
them. The foot-prints of birds and frogs, of crabs and worms, are
imprinted in the soil, like the faithful impression of a seal.[47]
9. Millions of forest-trees sprang up, towered to heaven, and fell, to
be crushed into the coal strata which make our winter fires. Hundreds
of feet measure the thickness of what were once succulent plants, but
pressed together like paper-pulp, and consolidated under a weight
absolutely immensurable. Yet there remain the scales of their stems, the
elegant reticulated patterns of their bark, the delicate tracery of
their leaf-nerves, indelibly depicted by an unpatented process of
"nature-printing." And when we examine the record,--the forms of the
leaves, the structure of the tissues, we get the same result as before,
that the plants belonged to a flora which had no species in common with
that which adorns the modern earth. Very gradually, and only after many
successions, not of individual generations, but of the cycles of
species, genera, and even families, did the vegetable creation conform
itself to ours.[48]
10. At length the species both of plants and animals grew,--not by
alteration of their specific characters, but by replacement of species
by species--more and more like what we have now on the earth, and
finally merged into our present flora and fauna, about the time when we
find the first geological traces of MAN.
11. During the course of these successive cycles of organic life, the
map of the world has changed many times. Up to a late period the ocean
washed over Mont Blanc and Mount Ararat; the continent of Europe was a
wide sea; then it was a Polynesia, then an Archipelago of great islands,
then a Continent much larger than it is now, with England united to it,
and the solid land stretching far away into the Atlantic;--then it sank
again, and was again raised, not all at once, but by several stages,
each of which has left its coast line, and its shingle beach. All these
changes must have been the work of vast periods of time.
"Excepting possibly, but not certainly, the higher parts of some
mountains, which at widely different epochs have been upheaved, and made
to elevate and pierce the stratified masses which once lay over them,
there is scarcely a spot on the earth's surface which has not been many
times in succession the bottom of the sea, and a portion of dry land.
In the majority of cases, it is shown, by physical evidences of the most
decisive kind, that each of those successive conditions was of extremely
long duration; a duration which it would be presumptuous to put into any
estimate of years or centuries; for any alteration, of which vestiges
occur in the zoological state and the mineral constitution of the
earth's present surface, furnishes no analogy (with regard to the nature
and continuance of causes), that approaches in greatness of character to
those changes whose evidences are discernible in almost any two
continuous strata. It is an inevitable inference, unless we are disposed
to abandon the principles of fair reasoning, that each one of such
changes in organic life did not take place till after the next preceding
condition of the earth had continued through a duration, compared with
which six thousand years appear an inconsiderable fraction of time."[49]
12. The climate of our atmosphere has undergone corresponding mutations.
At one time the Palms, the Treeferns, the Cycads of the tropical jungles
found their congenial home here: the Elephant, the Rhinoceros, and the
Tiger roamed over England; nay, dwelt in countless hosts on the
northern shores of Siberia: then the climate gradually cooled to a
temperate condition: then it became cold, and glaciers and icebergs were
its characteristic features: finally it became temperate again.
13. The icebergs and the glaciers were the ships and railways of past
epochs; they were freighted with their heavy but worthless cargoes of
rock-boulders and gravel, and set out on their long voyages and travels,
over sea and land, sometimes writing their log-books in ineffaceable
scratches on the rocky tables over which they passed, and at length
discharging their freights in harbours and bays, on inland plains, on
mountain sides and summits, where they remain unclaimed, free for any
trader in such commodities, without the ceremony of producing the
original bill of lading.
Let the remainder be told in the words of one of our most eloquent and
able geologists, Professor Sedgwick.
"The fossils demonstrate the time to have been _long_, though we cannot
say _how_ long. Thus we have generation after generation of shell-fish,
that have lived and died on the spots where we find them; very often
_demonstrating_ the lapse of _many years_ for a few perpendicular inches
of deposit. In some beds we have large, cold-blooded reptiles,
creatures of long life. In others, we have traces of ancient forests,
and enormous fossil trees, with concentric rings of structure, marking
the years of growth. Phenomena of this kind are repeated again and
again; so that we have three or four distinct systems of deposit, each
formed at a distinct period of time, and each, characterised by its
peculiar fossils. Coeval with the Tertiary masses, we have enormous
lacustrine deposits; sometimes made up of very fine thin laminae, marking
slow tranquil deposits. Among these laminae, we can find sometimes the
leaf-sheddings and the insects of successive seasons. Among them also we
find almost mountain-masses of the _Indusioe tubulatoe_ [the cases
of _Phryganeoe_], and other sheddings of insects, year after year.
Again, streams of ancient lava alternate with some of these lacustrine
tertiary deposits.
"In central France, a great stream of lava caps the lacustrine
limestone. At a _subsequent period_ the waters have excavated deep
valleys, cutting down into the lacustrine rock-marble many hundred feet;
and, at a newer epoch, anterior to the authentic history of Europe, new
craters have opened, and fresh streams of lava have run down the
existing valleys. Even in the Tertiary period we have thus a series of
demonstrative proofs of a long succession of physical events, each of
which required a long lapse of ages for its elaboration.