Copyright
Thomas B. (Thomas Brackett) Reed.

Modern eloquence; (Volume 5) online

. (page 20 of 38)
Online LibraryThomas B. (Thomas Brackett) ReedModern eloquence; (Volume 5) → online text (page 20 of 38)
Font size
QR-code for this ebook


of the American Navy, some years ago invented a most
ingenious machine, by which a considerable portion of the
superficial layer of the sea-bottom can be scooped out and
brought up from any depth to which the lead descends.
In 1853, Lieutenant Brooke obtained mud from the bot-
tom of the North Atlantic, between Newfoundland and
the Azores, at a depth of more than 10,000 feet, or two
miles, by the help of this sounding apparatus. The speci-
mens were sent for examination to Ehrenberg of Berlin,
and to Bailey of West Point, and those able microscopists
found that this deep-sea mud was almost entirely com-
posed of the skeletons of living organisms the greater
proportion of these being just like the Globigerince already
known to occur in the chalk.

Thus far, the work had been carried on simply in the
interests of science, but Lieutenant Brooke's method of
sounding acquired a high commercial value, when the en-
terprise of laying down the telegraph-cable between this
country and the United States was undertaken. For it
became a matter of immense importance to know, not only
the depth of the sea over the whole line along which the
cable was to be laid, but the exact nature of -the bottom,
so as to guard against chances of cutting or fraying the
strands of that costly rope. The Admiralty consequently
ordered Captain Dayman, an old friend and shipmate of
mine, to ascertain the depth over the whole line of the
cable, and to bring back specimens of the bottom. In
former days, such a command as this might have sounded
very much like one of the impossible things which the
young Prince in the Fairy Tales is ordered to do before
he can obtain the hand of the Princess. However, in the
months of June and July, 1857, my friend performed the
task assigned to him with great expedition and precision,



6iO THOMAS HENRY HUXLEY

without, so far as I know, having met with any reward
of that kind. The specimens of Atlantic mud which he
procured were sent to me to be examined and reported
upon.

The result of all these operations is, that we know the
contours and the nature of the surface-soil covered by the
North Atlantic for a distance of 1,700 miles from east to
west, as well as we know that of any part of the dry land.
It is a prodigious plain one of the widest and most even
plains in the world. If the sea were drained off, you
might drive a wagon all the way from Valentia, on the
west coast of Ireland, to Trinity Bay, in Newfoundland.
And, except upon one sharp incline about 200 miles from
Valentia, I am not quite sure that it would even be neces-
sary to put the skid on, so gentle are the ascents and de-
scents upon that long route. From Valentia the road
would lie down-hill for about 200 miles to the point at
which the bottom is now covered by 1,700 fathoms of sea-
water. Then would come the central plain, more than a
thousand miles wide, the inequalities of the surface of
which would be hardly perceptible, though the depth of
water upon it now varies from 10,000 to 15,000 feet; and
there are places in which Mont Blanc might be sunk with-
out showing its peak above water. Beyond this, the
ascent on the American side commences, and gradually
leads, for about 300 miles, to the Newfoundland shore.

Almost the whole of the bottom of this central plain
(which extends for many hundred miles in a north and
south direction) is covered by a fine mud, which, when
brought to the surface, dries into a grayish white friable
substance. You can write with this on a blackboard, if
you are so inclined; and, to the eye, it is quite like very
soft, grayish chalk. Examined chemically, it proves to be
composed almost wholly of carbonate of lime ; and if you
make a section of it, in the same way as that of the piece
of chalk was made, and view it with the microscope, it
presents innumerable Globigerince embedded in a granular
matrix. Thus this deep-sea mud is substantially chalk.
I say substantially, because there are a good many minor
differences ; but as these have no bearing on the question
immediately before us, which is the nature of the Globi-
gerince of the chalk, it is unnecessary to speak of them.



ON A PIECE OF CHALK 6ll

Globigerincv of every size, from the smallest to the
largest, are associated together in the Atlantic mud, and
the chambers of many are filled by a soft animal matter.
This soft substance is, in fact, the remains of the creature
to which the Globigcrince shell, or rather skeleton, owes its
existence and which is an animal of the simplest imagin-
able description. It is, in fact, a mere particle of living
jelly, without defined parts of any kind without a mouth,
nerves, muscles, or distinct organs, and only manifesting
its vitality to ordinary observation by thrusting out and
retracting from all parts of its surface, long filamentous
processes, which serve for arms and legs. Yet this amor-
phous particle, devoid of everything which, in the higher
animals, we call organs, is capable of feeding, growing,
and multiplying; of separating from the ocean the small
proportion of carbonate of lime which is dissolved in sea-
water; and of building up that substance into a skeleton
for itself, according to a pattern which can be imitated
by no other known agency.

The notion that animals can live and flourish in the sea,
at the vast depths from which apparently living Globi-
gerince have been brought up, does not agree very well
with our usual conceptions respecting the conditions of
animal life ; and it is not so absolutely impossible as it
might at first sight appear to be, that the Globigerintz of
the Atlantic sea-bottom do not live and die where they
are found.

As I have mentioned, the soundings from the great
Atlantic plain are almost entirely made up of Globigerina,
with the granules which have been mentioned, and some
few other calcareous shells; but a small percentage of
the chalky mud perhaps at most some five per cent, of
it is of a different nature, and consists of shells and
skeletons composed of silex, or pure flint. These silicious
bodies belong partly to the lowly vegetable organisms
which are called Diatomacea, and partly to the minute, and
extremely simple, animals, termed Radiolaria. It is quite
certain that these creatures do not live at the bottom of
the ocean, but at its surface where they may be obtained
in prodigious numbers by the use of a properly con-
structed net. Hence it follows that these silicious organ-
isms, though they are not heavier than the lightest dust,



612 THOMAS HENRY HUXLEY '

must have fallen, in some cases, through fifteen thousand
feet of water, before they reached their final resting-place
on the ocean floor. And considering how large a surface
these bodies expose in proportion to their weight, it is
probable that they occupy a great length of time in mak-
ing their burial journey from the surface of the Atlantic
to the bottom.

But if the Radiolaria and Diatoms are thus rained upon
the bottom of the sea, from the superficial layer of its
waters in which they pass their lives, it is obviously pos-
sible that the Globigerincc may be similarly derived ; and if
they were so, it would be much more easy to understand
how they obtain their supply of food than it is at present.
Nevertheless, the positive and negative evidence all points
the other way. The skeletons of the full-grown, deep-
sea Globigerincz are so remarkably solid and heavy in pro-
portion to their surface as to seem little fitted for float-
ing; and, as a matter of fact, they are not to be found
along with the Diatoms and Radiolaria in the uppermost
stratum of the open ocean. It has been observed, again,
that the abundance of Globigerince, in proportion to other
organisms, of like kind, increases with the depth of the
sea ; and that deep-water Globigerincc are larger than those
which live in shallower parts of the sea; and such facts
negative the supposition that these organisms have been
swept by currents from the shallows into the deeps of the
Atlantic. It therefore seems to be hardly doubtful that
these wonderful creatures live and die at the depths in
which they are found.

However, the important points for us are, that the liv-
ing Globigerincc are exclusively marine animals, the skele-
tons of which abound at the bottom of deep seas; and
that there is not a shadow of reason for believing that the
habits of the Globigerincc of the chalk differed from those
of the existing species. But if this be true, there is no
escaping the conclusion that the chalk itself is the dried
mud of an ancient deep sea.

In working over the soundings collected by Captain
Dayman, I was surprised to find that many of what I have
called the " granules " of that mud were not, as one might
have been tempted to think at first, the mere powder and
waste of Globigcrincc, but that they had a definite form and



ON A PIECE OF CHALK 613

size. I termed these bodies " coccoliths," and doubted
their organic nature. Dr. Wallich verified my observa-
tion, and added the interesting discovery that, not unfre-
quently, bodies similar to these " coccoliths " were aggre-
gated together into spheroids, which he termed " cocco-
spheres." So far as we knew, these bodies, the nature of
which is extremely puzzling and problematical, were pecu-
liar to the Atlantic soundings. But, a few years ago, Mr.
Sorby, in making a careful examination of the chalk by
means of thin sections and otherwise, observed, as Ehren-
berg had done before him, that much of its granular basis
possesses a definite form. Comparing these formed par-
ticles with those in the Atlantic soundings, he found the
two to be identical; and thus proved that the chalk, like
the surroundings, contains these mysterious coccoliths
and coccospheres. Here was a further and most inter-
esting confirmation, from internal evidence, of the essen-
tial identity of the chalk with modern deep-sea mud.
Globigerince, coccoliths, and coccospheres are found as the
chief constituents of both, and testify to the general simi-
larity of the conditions under which both have been
formed.

The evidence furnished by the hewing, facing, and
superposition of the stones of the Pyramids, that these
structures were built by men, has no greater weight than
the evidence that the chalk was built by Globigerina ; and
the belief that those ancient pyramid-builders were ter-
restrial and air-breathing creatures like ourselves, is not
better based than the conviction that the chalk-makers
lived in the sea. But as our belief in the building of the
Pyramids by men is not only grounded on the internal
evidence afforded by these structures, but gathers
strength from multitudinous collateral proofs, and is
clinched by the total absence of any reason for a contrary
belief; so the evidence drawn from the Globigerina that
the chalk is an ancient sea-bottom, is fortified by innum-
erable independent lines of evidence; and our belief in
the truth of the conclusion to which all positive testimony
tends, receives the like negative justification from the fact
that no other hypothesis has a shadow of foundation.

It may be worth while briefly to consider a few of these
collateral proofs that the chalk was deposited at the bot-



614 THOMAS HENRY HUXLEY

torn of the sea. The great mass of the chalk is composed,
as we have seen, of the skeletons of Globigcrincu, and other
simple organisms, embedded in granular matter. Here
and there, however, this hardened mud of the ancient sea
reveals the remains of higher animals which have lived
and died, and left their hard parts in the mud, just as the
oysters die and leave their shells behind them, in the mud
of the present seas.

There are, at the present day, certain groups of animals
which are never found in fresh waters, being unable to
live anywhere but in the sea. Such are the corals ; those
corallines which are called Polyzoa; those creatures which
fabricate the lamp-shells, and are called Brachiopoda; the
pearly Nautilus, and all animals allied to it; and all the
forms of sea-urchins and star-fishes. Not only are all
these creatures confined to salt water at the present day ;
but, so far as our records of the past go, the conditions
of their existence have been the same : hence, their occur-
rence in any deposit is as strong evidence as can be ob-
tained, that that deposit was formed in the sea. Now
the remains of animals of all kinds which have been
enumerated, occur in the chalk, in greater or less abun-
dance ; while not one of those forms of shell-fish which
are characteristic of fresh water has yet been observed
in it.

When we consider that the remains of more than three
thousand distinct species of aquatic animals have been
discovered among the fossils of the chalk, that the great
majority of them are of such forms as are now met with
only in the sea, and that there is no reason to believe
that any one of them inhabited fresh water the collateral
evidence that the chalk represents an ancient sea-bottom
acquires as great force as the proof derived from the
nature of the chalk itself. I think you will now allow
that I did not overstate my case when I asserted that we
have as strong grounds for believing that all the vast area
of dry land, at present occupied by the chalk, was once at
the bottom of the sea, as we have for any matter of his-
tory whatever ; while there is no justification for any other
belief.

No less certain it is that the time during which the
countries we now call south-east England, France, Ger-



ON A PIECE OF CHALK



615



many, Poland, Russia, Egypt, Arabia, Syria, were more
or less completely covered by a deep sea, was of consider-
able duration. We have already seen that the chalk is, in
places, more than a thousand feet thick. I think you will
agree with me, that it must have taken some time for the
skeletons of animalcules of a hundredth of an inch in
diameter to heap up such a mass as that. I have said
that throughout the thickness of the chalk the remains of
other animals are scattered. These remains are often in
the most exquisite state of preservation. The valves of
the shell-fishes are commonly adherent; the long spines
of some of the sea-urchins, which would be detached by
the smallest jar, often remain in their places. In a word,
it is certain that these animals have lived and died when
the place which they now occupy was the surface of as
much of the chalk as had then been deposited; and that
each has been covered up by the layer of Globigerina mud,
upon which the creatures embedded a little higher up
have, in like manner, lived and died. But some of these
remains prove the existence of reptiles of vast size in the
chalk sea. These lived their time, and had their ances-
tors and descendants, which assuredly implies time, rep-
tiles being of slow growth.

There is more curious evidence, again, that the process
of covering up, or, in other words, the deposit of Globi-
gerina skeletons, did not go on very fast. It is demon-
strable that an animal of the cretaceous sea might die,
that its skeleton might lie uncovered upon the sea-bottom
long enough to lose all its outward coverings and append-
ages by putrefaction; and that, after this had happened,
another animal might attach itself to the dead and naked
skeleton, might grow to maturity, and might itself die be-
fore the calcareous mud had buried the whole.

Cases of this kind are admirably described by Sir
Charles Lyell. He speaks of the frequency with which
geologists find in the chalk a fossilized sea-urchin, to
which is attached the lower valve of a Crania. This is a
kind of shell-fish, with a shell composed of two pieces, of
which, as in the oyster, one is fixed and the other free.
"The upper valve is almost invariably wanting, though
occasionally found in a perfect state of preservation in the
white chalk at some distance. In this case, we see clearly



6l6 THOMAS HENRY HUXLEY

that the sea-urchin first lived from youth to age, then
died and lost its spines, which were carried away. Then
the young Crania adhered to the bared shell, grew and
perished in its turn ; after which, the upper valve was sepa-
rated from the lower, before the Echinus became en-
veloped in chalky mud."

A specimen in the Museum of Practical Geology in
London, still further prolongs the period which must have
elapsed between the death of the sea-urchin, and its
burial by the Globigerinc?. For the outward face of the
valve of a Crania, which is attached to a sea-urchin, (Mi-
cr aster), is itself overrun by an incrusting coralline, which
spreads thence over more or less of the surface of the sea-
urchin. It follows that, after the upper valve of the Crania
fell off, the surface of the attached valve must have re-
mained exposed long enough to allow of the growth of
the whole coralline, since corallines do not live embedded
in mud.

The progress of knowledge may, one day, enable us to
deduce from such facts as these the maximum rate at
which the chalk can have accumulated, and thus to arrive
at the minimum duration of the chalk period. Suppose
that the valve of the Crania upon which a coralline has
fixed itself in the way just described, is so attached to the
sea-urchin that no part of it is more than an inch above
the face upon which the sea-urchin rests. Then, as the
coralline could not have fixed itself, if the Crania had been
covered up with chalk mud, and could not have lived had
itself been so covered, it follows, that an inch of chalk
mud could not have accumulated within the time between
the death and decay of the soft parts of the sea-urchin
and the growth of the coralline to the full size which it
has attained. If the decay of the soft parts of the sea-
urchin; the attachment, growth to maturity, and decay
of the Crania; and the subsequent attachment and growth
of the coralline, took a year (which is a low estimate
enough), the accumulation of the inch of chalk must have
taken more than a year; and the deposit of a thousand
feet of chalk must, consequently, have taken more than
twelve thousand years.

The foundation of all this calculation is, of course, a
knowledge of the length of time the Crania and the coral-



ON A PIECE OF CHALK

line needed to attain their full size ; and, on this head, pre-
cise knowledge is at present wanting. But there are circum-
stances which tend to show, that nothing like an inch of
chalk has accumulated during the life of a Crania; and, on
any probable estimate of the length of that life, the chalk
period must have had a much longer duration than that
thus roughly assigned to it.

Thus, not only is it certain that the chalk is the mud
of an ancient sea-bottom; but it is no less certain, that
the chalk sea existed during an extremely long period,
though we may not be prepared to give a precise estimate
of the length of that period in years. The relative dura-
tion is clear, though the absolute duration may not be de-
finable. The attempt to affix any precise date to the
period at which the chalk sea began, or ended, its exist-
ence, is baffled by difficulties of the same kind. But the
relative age of the cretaceous epoch may be determined
with as great ease and certainty as the long duration of
that epoch.

You will have heard of the interesting discoveries re-
cently made, in various parts of Western Europe, of flint
implements, obviously worked into shape by human
hands, under circumstances which show conclusively that
man is a very ancient denizen of these regions. It has
been proved that the whole populations of Europe, whose
existence has been revealed to us in this way, consisted
of savages, such as the Esquimaux are now; that, in the
country which is now France, they hunted the reindeer,
and were familiar with the ways of the mammoth and
the bison. The physical geography of France was in
those days different from what it is now the River
Somme, for instance, having cut its bed a hundred feet
deeper between that time and this; and, it is probable,
that the climate was more like that of Canada or Siberia,
than that of Western Europe.

The existence of these people is forgotten even in the
traditions of the oldest historical nations. The name
and fame of them had utterly vanished until a few years
back ; and the amount of physical change which has been
effected since their day renders it more than probable
that, venerable as are some of the historical nations, the
workers of the chipped flints of Hoxne or of Amiens are



618 THOMAS HENRY HUXLEY

to them, as they are to us, in point of antiquity. Bift, if
we assign to these hoar relics of long-vanished genera-
tions of men the greatest age that can possibly be claimed
for them, they are not older than the drift, or boulder
clay, which, in comparison with the chalk, is but a very
juvenile deposit. You need go no further than your own
sea-board for evidence of this fact. At one of the most
charming spots on the coast of Norfolk, Cromer, you will
see the boulder clay forming a vast mass, which lies upon
the chalk, and must consequently have come into exist-
ence after it. Huge boulders of chalk are, in fact, in-
cluded in the clay, and have evidently been brought to
the position they now occupy by the same agency as that
which has planted blocks of syenite from Norway side by
side with them.

The chalk, then, is certainly older than the boulder
clay. If you ask how much, I will again take you no
further than the same spot upon your own coasts for
evidence. I have spoken of the boulder clay and drift as
resting upon the chalk. That is not strictly true. Inter-
posed between the chalk and the drift is a comparatively
insignificant layer, containing vegetable matter. But
that layer tells a wonderful history. It is full of stumps
of trees standing as they grew. Fir-trees are there with
their cones, and hazel-bushes with their nuts ; there stand
the stools of oak and yew-trees, beeches, and alders.
Hence this stratum is appropriately called the " forest-
bed."

It is obvious that the chalk must have been upheaved
and converted into dry land, before the timber trees could
grow upon it. As the bolls of some of these trees are
from two to three feet in diameter, it is no less clear that
the dry land thus formed remained in the same condition
for long ages. And not only do the remains of stately
oaks and well-grown firs testify to the duration of this
condition of things, but additional evidence to the same
effect is afforded by the abundant remains of elephants,
rhinoceroses, hippopotamuses, and other great wild
beasts, which it has yielded to the zealous search of such
men as the Rev. Mr. Gunn. When you look at such a
collection as he has formed, and bethink you that these
elephantine bones did veritably carry their owners about,



ON A PIECE OF CHALK 619

and these great grinders crunch, in the dark woods of
which the forest-bed is now the only trace, it is impossible
not to feel that they are as good evidence of the elapse
of time as the annual rings of the tree-stumps.

Thus there is a writing upon the wall of cliffs at Cro-
mer, and whoso runs may read it. It tells us, with an
authority which cannot be impeached, that the ancient
sea-bed of the chalk sea was raised up, and remained dry
land, until it was covered with forest, stocked with the
great game the spoils of which have rejoiced your geolo-
gists. How long it remained in that condition cannot
be said ; but " the whirligig of time brought its revenges "
in those days as in these. That dry land, with the bones
and teeth of generations of long-livecl elephants, hidden
away among the gnarled roots and dry leaves of its
ancient trees, sank gradually to the bottom of the icy
sea, which covered it with huge masses of drift and
boulder clay. Sea-beasts, such as the walrus, now re-
stricted to the extreme north, paddled about where birds
had twittered among the topmost twigs of the fir-trees.
How long this state of things endured we know not, but
at length it came to an end. The upheaved glacial mud
hardened into the soil of modern Norfolk. Forests grew
once more, the wolf and the beaver replaced the reindeer
and the elephant ; and at length what we call the history
of England dawned.

Thus you have, within the limits of your own country,
proof that the chalk can justly claim a very much greater
antiquity than even the oldest physical traces of mankind.
But we may go further and demonstrate, by evidence of
the same authority as that which testifies to the exist-
ence of the father of men, that the chalk is vastly older
than Adam himself. The Book of Genesis informs us



Online LibraryThomas B. (Thomas Brackett) ReedModern eloquence; (Volume 5) → online text (page 20 of 38)