up the Witness on whose veracity they have been wont to rely; but they
are unable to answer the arguments brought against him.
Counsel for the Brachy-chronology speaks. "We respectfully ask the Court
for another hearing. Will our learned brother permit his witness briefly
to recapitulate his testimony, and we will endeavour to examine it once
more; for we think we shall be able to detect some flaw in it?" Rule
granted.
WITNESS FOR THE MACRO-CHRONOLOGY.
The following, then, is the substance of what the witness deposes. He is
not a living witness; his testimony, therefore, is not oral, but
written--lithographed, in fact. It consists of a number of documents,
which are couched in a language and character not to be understood
without some previous study, but yet very capable of translation--very
clear and unmistakeable. The following, I say, is a condensed summary of
the leading points.
If a curious person had watched the process of making the excavations
that were preliminary to the boring of the Thames Tunnel, he would have
observed that the labourers exposed successive layers of earth,
differing much in colour, consistency, and general character. First, an
accumulation of soil, consisting of decayed vegetable and animal matter,
mingled with broken pottery, and other rubbish of man's production, was
removed; then a layer of sand, gravel, and river mud; then a bed of
reddish clay; then a layer of clay, mixed with silt or fine sandy mud;
then a thin layer of silt, much filled with shells; then a stratum of
stiff blue clay; then a layer of clay of more mottled character,
containing a portion of silt, and some shells; then a stratum of very
firm clay, so solid that it required to be broken with wedges; then a
bed of gravel and sand of a green colour; and finally, a similar layer,
but of a coarser texture.
In the course of the hundred feet or so of perpendicular depth thus
exposed, he would have seen a succession of layers, apparently deposited
upon one another. But as yet he would have formed a very inadequate
notion of the stratification of the earth's crust.
With the knowledge thus gained, however, let him now make a little
excursion into Hertfordshire; we will suppose at the time when the
cuttings for the Great Northern Railway were being made. When he came
near Cheshunt, he would see that the London clay, which he found
underlying the Thames, crops out, or disappears by the stratum coming
obliquely to the surface. He would see, however, another bed of
clay--the plastic clay--beneath this, which now forms the superficial
stratum, and continues to do so, till he gets beyond Hertford. There
this stratum crops out; and the chalk, which for some time he has seen
to underlie the plastic clay, now comes to the surface.
Business or pleasure calls him to Bridlington on the Yorkshire coast;
and he determines to make a pedestrian tour across the diameter of
England to Whitehaven. He soon recognises the chalk, which constitutes
the Wolds, and rises to about 800 feet above the sea level. Below its
escarpment he traces the Kimmeridge clay, the uppermost of a series of
strata more than 2,000 feet in thickness, that constitute the Oolitic
system--including, among others, the coralline oolite, the calcareous
grit, the cornbrash, thin, but rich in fossils; the lower sandstone and
coal of the Cleveland hills, the alum shale, the marlstone, and the
lower lias shale.
Then comes a stratum of the saliferous system or the new red sandstone,
with the red marls, perhaps not much short of a thousand feet deep.
Below them the observer finds the strata of the magnesian limestone
formation, for nearly 400 feet, resting on the great coal formations of
vast depth. Of these the coal field of the West Riding is not less than
4,000 feet in depth, and beneath it lie the millstone grit, and the
mountain limestone, 2,500 feet more, the latter displayed in noble
grandeur on the faces of those wall-like precipices that inclose the
romantic dales of the Swale and the Ure, and that subsequently tower in
magnificent altitude on the sides of Pennygant and Ingleborough.
[Illustration: GEOLOGICAL SECTION OF YORKSHIRE.]
On the western escarpment of the Pennine ridge, just as the traveller is
entering Westmoreland, he would detect the bottom of the limestone; and
here he would have an opportunity of seeing, what is rare in these
parts, a stratum of the old red sandstone, lying between the former and
the slaty rocks of the Cumbrian formations. And here at length, in the
wild and magnificent scenery of these mountains, he sees the primitive
and transition series, the greenstone, the sienite, and the granite,
each of which is discernible in succession on the face of one or other
of the lofty Fells of Cumberland.
Our traveller now comes home, and, musing on what he has seen, counts up
some thirty or more distinct strata lying in regular succession one on
another. But he has not seen all the world, nor even all England; but he
reads the results of many independent observations, and finds that
while, for the most part, the strata which he has seen are common to the
whole surface of the globe, and while the order of their superposition
is invariable everywhere, others are in some parts added, while perhaps
some of those which he has observed are locally absent. Thus he is able
to form a more distinct idea of the stratification of the earth's crust
as a whole. It is composed of about forty distinct formations, generally
increasing in thickness as we go downwards, so that the whole cannot be
much less than ten miles in depth, supposing them in any locality to be
all present, and to be lying in the horizontal plane.
Mathematicians have satisfactorily determined that the mean density of
the globe is about five-and-a-half times that of water, or about twice
that of granite, a fact inconsistent with any other supposition than
that the interior is occupied by substances maintained in a fluid state
by intense heat. The lowest point that has yet been patent to human
observation is occupied by the granite, a compound rock, which bears
evident marks of having been once in a state of fusion, and of having
cooled slowly, and that under immense pressure, contracting and
crystallizing as it parted with its heat. There is every reason to
believe that the granite is not defined at its inferior surface, but
that it merges into the molten mass, probably still solidifying.
After the outer portion of the granite had cooled sufficiently to become
solid, there is evidence that it was covered by water, agitated by
powerful currents, and probably in a heated state. The action of these
currents disintegrated the rock, and deposited the constituent
substances at the bottom of the sea--on the surface, and in the hollows,
of the granite. For there is reason to think that the contraction of the
primitive rock in the process of cooling, produced irregular undulations
or crumplings of the surface, and frequent fractures and dislocations,
elevating some parts and depressing others. The gneiss, the mica-schist,
and the clay-slate, which are found immediately overlying the granitic
rock in strata of vast thickness, are but the components of granite,
separated and rearranged. "If we imagine common granite coarsely
pounded, and thrown into a vessel of water, it will arrange itself at
the bottom of the vessel in a condition very much like that of gneiss,
which is indeed nothing else than stratified granite. If the water in
which the pounded rock is thrown is moving along at a slow rate, and the
clayey portion of the granite, called _felspar_, happens to be somewhat
decomposed, as it often is, then the felspar (which is so truly _clay_
that it makes the best possible material for the use of the potteries)
and the thin shining plates of mica, will be carried further by the
water than the lumps of white quartz or flint sand, which, with the
other two ingredients, made up the granite; and the two former will be
deposited in layers, which, by passing a galvanic current through them,
would in time become mica-schist. If the mica were absent, or if the
clay were deposited without it, owing to any cause, then a similar
galvanic current would turn the deposit into something like
clay-slate."[25]
The deposition of these strata, being formed out of granite, supposes
the pre-existence of that rock; and as they occur in vast thicknesses,
even of many thousand feet, then separation, deposition, and
reconsolidation must have occupied, however rapidly we may suppose the
processes to have been accomplished, considerable periods of time.
In these lower rocks, no trace of organic remains has been found. The
shoreless ocean that covered the cooling surface of the earth's crust,
harboured no polype or sponge, no rhizopod or infusorium, and the angles
and clefts of the granite were fringed by no fucus, or conferva: all was
waste and void. And if certain parts were elevated above the waters, the
bleak and barren points were not clothed with grass, or moss, or even a
lichen, and no animal wandered over their ridges. Or, if such did exist,
either in land or water, all vestiges of their presence have been
destroyed by the agency of the intense heat that subsequently prevailed.
But, in the numerous strata that overlie the rocks of granitic origin,
there are found, in varying abundance, proofs that, when they were
deposited, the surface of our earth had become the abode of organic
life. Zoophytes lived in the ocean, some of which were engaged in
secreting lime from the water, and depositing it in coral-reefs; stalked
and jointed Star-fishes waved like lilies of stone from the submerged
rocks; Sea-worms twined over the mud; mailed Crustaceans swam to and
fro; and Mollusks, both bivalve and univalve, crawled over the ledges or
reposed in the crevices. The remains of these occur in the Silurian
rocks that lie immediately on the primitive granitic formations of
Cumberland and North Wales. The construction of the coral-reefs of that
deposit, in particular, must have occupied a lengthened period,
continuing to go on, "month after month, year after year, century after
century, until at length the depth changed, in which they could most
conveniently live, or, owing to some other cause, their labours were
brought to a close, and they disappeared from amongst existing
species."[26]
[Illustration: A TRILOBITE.
(_Calymene Blumenbachii._)
_a._ extended; back view. _b._ rolled up; side view. _c._ rolled up;
front view.]
Not a single species, or even a single genus of those early strata, is
identical with any that exists now. The Coral-polypes, for instance,
while allied to ours, are quite distinct from them, though endowed with
similar powers and habits, so that we may reason from analogy on the
laws of their deposits. The Trilobites were allied to the tiny
water-fleas (_Entomostraca_) of the present day: like the _Oniscidae_
(wood-lice, buttons, &c.) of our gardens, they had the habit of rolling
their plated bodies into a ball. These are found in great numbers, their
remains often heaped on one another. The Mollusca of those seas were
chiefly of the class _Cephalopoda_--one of the least populous
now-a-days, but then existing in vast number and variety; the
Brachiopoda, Conchifera, and Gastropoda, were, however, well represented
also.
Such were the inhabitants of the sea during the Silurian period, in
which a series of solid deposits were made, the aggregate, probably,
exceeding 50,000 feet in thickness. Each deposit, though not more than a
few inches in depth, "is provided with its own written story, its sacred
memoranda, assuring us of the regularity and order that prevailed, and
of the perfect uniformity of plan."
Over all these, however, we see laid the strata of the Devonian system,
especially the old red sandstone, which in some places attains a
thickness of 10,000 feet. It is composed of a coarse agglomeration of
broken fragments of the old granitic rocks, rolled and tossed about,
apparently by the ever-breaking waves of shingle-beaches, until the
hardest stones are worn into rounded pebbles by long and constant
attrition.
An examination of the old red sandstone, as is seen in Herefordshire,
will aid us in forming a notion of the time required for its production.
It is composed of fragments obtained by the disintegration of more
ancient rocks, which, by a long process of rolling together in a
breaking sea, or in the bed of a rapid current, have lost all their
angles. The pebbles, thus worn, have at length settled,--the heaviest
lowest,--and the whole has been consolidated into firm rock. "In many
places," says Dr. Pye Smith, "the upper part of this vast formation is
of a closer grain, showing that it was produced by the last and finest
deposits of clayey and sandy mud, tinged, as the whole is, with oxides
and carbonates of iron, usually red, but often of other hues. But,
frequently, the lower portions, sometimes dispersed heaps, and,
sometimes, the entire formation, consist of vast masses of conglomerate,
the pebbles being composed of quartz, granite, or some other of the
earliest kinds; and thus showing the previous rocks, from whose
destruction they have been composed. Let any person first acquire a
conception of the extent of this formation, and of its depth, often many
hundreds, and, sometimes, two or three thousand feet; (but such a
conception can scarcely be formed without actual inspection;) then let
him attempt to follow out the processes which the clearest evidence of
our senses shows to have taken place; and let him be reluctant and
sceptical to the utmost that he can, he cannot avoid the impression that
ages innumerable must have rolled over the world, in the making of this
single formation."[27]
Here, Fishes are added to the Invertebrate Animals. A sort of Shark with
the mouth terminal, instead of beneath the head, was the earliest
representative of this class. But closely following on this, were some
curious species, enveloped in plate mail, and remarkable for the
singularity of their forms, as the _Cephalaspis_ and the _Pterichthys_.
[Illustration: CEPHALASPIS.]
This great period passed away, and was succeeded by that of the
Carboniferous deposits, indicative of a vast change in the physical
character of the earth's surface and atmosphere. This change of
character may be briefly summed up as consisting of an immense abundance
of lime in the ocean, and of an equally vast charge of carbonic acid in
the atmosphere.
Strata of limestone, 2,500 feet in thickness, were accumulated in the
ocean by the labours of Coral-polypes, allied to, but totally distinct
from, those which had previously existed in the primary system. On the
floor of a shallow sea, which then occupied the middle of what is now
England, the coral reefs rose perpetually towards the day, atom by atom,
the strata on which they were founded slowly and steadily sinking ever
to a lower level, while successive generations of the industrious
zoophytes wrought upwards, to maintain their position within reach of
the light and warmth. What period of time was requisite for the
aggregation of coral structure to the perpendicular thickness of 2,500
feet?
While this was going on, other Invertebrata were living in the shallow
seas, mostly differing from the older species, which had become by this
time extinct. Encrinites and Sea-urchins existed; some _Foraminifera_
were astonishingly abundant; the _Cephalopoda_ and the _Brachiopoda_
presented a vast variety of species; and about seventy sorts of Fishes,
mostly Sharks, characterised the age.
On the coral limestone lies a sort of conglomerate, known as the
millstone grit; and on this is laid that source of Britain's eminence,
the _coal_. The coal measures of South Wales are estimated at 12,000
feet in thickness. The profusion of vegetable life that must have
combined to make the coal in these, has no parallel in this age; no, not
in the teeming forests of South America, or the great isles of the
Oriental Archipelago. The circumstances which favoured this enormous
development of plants, seem never to have been repeated in subsequent
ages, since the coal measures which are found in the later strata are
thin and inconsiderable, compared with those we are considering.
M. Adolphe Brogniart suggests that in this period, from some source or
other, carbonic acid was generated in vast abundance; or, at least, that
it existed in the air, in a far greater proportion than it does now; and
it is singularly confirmatory of his view, that terrestrial animals, to
which this gas is fatal, have left almost no traces of their existence,
during the age of these vast forests--a circumstance otherwise strange
and unaccountable.
"Those parts," says Mr. Ansted, "of the great carboniferous series which
generally include the beds of coral, consist of muddy and sandy beds,
alternating with one another, and with the coal itself. Some of them
would appear to be of fresh-water, and some of marine origin; and they
abound, for the most part, with remains of the leaves of Ferns and
fern-like trees, together with the crushed trunks of these and other
trees, whose substance may have contributed to form the great
accumulations of bituminised and other vegetable carbon obtained from
these strata.
"It is not easy to communicate such an idea of beds of coal as shall
enable the reader to understand clearly the nature of the circumstances
under which they may have been deposited, and the time required for this
purpose. The actual total thickness of the different beds in England
varies considerably in different districts, but appears to amount, in
the Lancashire coal-field, to as much as 150 feet. In North America
there is a coal-field of vast extent, in which there appears at least as
great a thickness of workable coal as in any part of England; while in
Belgium and France the thickness is often much less considerable,
although the beds thicken again still further to the east.
"But this account of the thickness of the beds gives a very imperfect
notion of the quantity of vegetable matter required to form them; and,
on the other hand, the rate of increase of vegetables, and the quantity
annually brought down by some great rivers, both of the eastern and
western continents, is beyond all measure greater than is the case in
our drier and colder climate. Certain kinds of trees which contributed
largely to the formation of the coal, seem to have been almost entirely
succulent, and capable of being squeezed into a small compass during
partial decomposition. This squeezing process must have been conducted
on a grand scale, both during and after the formation of separate beds;
and each bed in succession was probably soon covered up by muddy and
sandy accumulations, now alternating with the coal in the form of shale
and grit-stone. Sometimes, trunks of trees caught in the mud would be
retained in a slanting or nearly vertical position, while the sands were
accumulating round them; sometimes the whole would be quietly buried,
and soon cease to exhibit any external marks of vegetable origin.[28]
"To relate the various steps in the formation of a bed of coal, and the
gradual superposition of one bed upon another, by which at length the
whole group of the coal-measures was completed, would involve an amount
of detail little adapted to these pages; and when it is remembered that
the woody fibres, after being deposited, had to be completely changed,
and the whole character of the vegetable modified, before it could be
reduced to the bituminous, brittle, almost crystalline mineral now dug
out of the earth for fuel, it will rather seem questionable whether the
origin of coal was certainly and necessarily vegetable, than reasonable
to doubt the importance of the change that has taken place, and the
existence of extraordinary means to produce that change. Nothing,
however, is more certain than that all coal was once vegetable; for in
most cases woody structure may be detected under the microscope; and
this, if not in the coal in its ordinary state, at least in the burnt
ashes which remain after it has been exposed to the action of heat, and
has lost its bituminous and semi-crystalline character. This has been
too well and too frequently proved by actual experiment, to require more
than the mere statement of the fact."[29]
An eminent practical geologist thus essays to guess the age of the
coal-fields, and of the sandstone that underlies it.
"The great tract of peat near Stirling has demanded [for its formation]
two thousand years; for its registry is preserved by the Roman works
below it. It is but a single bed of coal. Shall we multiply it by 100?
We shall not exceed,--far from it,--did we allow 200,000 years for the
production of the coal-series of Newcastle, with all its rocky strata. A
Scottish lake does not shoal at the rate of half a foot in a century;
and that country presents a vertical depth of far more than 3,000 feet
in the single series of the oldest sandstone. No sound geologist will
accuse a computer of exceeding, if he allow 600,000 years for the
production of _this series alone_. And yet what are the coal deposits,
and what the oldest sandstone, compared to the entire mass of the
strata?"[30]
The conjecture, that the whole of the vegetable material now
constituting the coal, was the growth of the antediluvian centuries, and
that it was floated away and deposited by the flood, is untenable. In
not a few instances trunks are found broken, and worn by water-action;
but the great mass warrants the conclusion that trees of vast dimensions
and of close array--dense, majestic forests, such as now occur only in
the most humid regions of the tropics--were submerged in their native
abodes, lying where they fell, and where they have left the impressions,
side by side, on the upper and under surfaces of the shale, of their
delicate peculiarities of structure, which would have been totally
obliterated, if the trees had been sea-borne and shore-rolled, as
pretended. The result of a careful and minute examination of the
phenomena of coal, by Mr. Binney, is, that the vegetable matter now
forming coal had grown in vast _marine_ swamps, subjected to a series of
_subsidences_ with long intervals of repose; that the trees, and perhaps
smaller plants, were submerged under _tranquil_ water, in the places of
their growth; and that very inconsiderable portions, if any, of the
beds, are owing to drifting.[31]
While the coal was in process of deposition, the sea was occupied with
Invertebrata, not widely differing from those which had marked the
previous eras.
Fishes, however, were advancing in development; and several new and
strange forms, some of them of gigantic dimensions and formidable
armature, were introduced. These were chiefly remarkable for their
affinities with Reptiles (whence they are often called _Sauroid_
Fishes); and one of them--_Megalichthys_--was famished with jaws of
serried teeth, surpassing those of the crocodile. With these were
associated other and more ordinary Fishes; and swarms of Sharks of many
species, and varying much in size, roved through the sea, maintaining
the same pirate character as their representatives of our modern
seas--fierce, subtle, voracious, and powerful.
At this time, too, appeared the earliest Reptiles, chiefly of the
Amphibia sub-class. Some of these are known only by their foot-prints;
and the late Hugh Miller has graphically described the appearance of
some of these, which, he met with marking the roof of a coal-mine, four
hundred feet below the surface. These must have been _Batrachia_ of
large size, as the fore feet were thirteen inches apart across the
breast.[32] They will be alluded to again.
With these exceptions, remains of terrestrial animals are, as has
already been observed, rare in this formation.
III.
THE WITNESS FOR THE MACRO-CHRONOLOGY.
(CONTINUED.)
"Always distrust very plain cases: beware lest a snake
suddenly start out upon you, in the shape of some concealed
and utterly unexpected difficulty."--WARREN: _Law Studies_.