Transcriber Note
Text emphasis is denoted as _Italics_ and =Bold=. Whole and fractional
parts of numbers as 123-4/5.
THOUGHTS ON A PEBBLE.
[Illustration]
REEVE, BENHAM, AND REEVE, PRINTERS AND PUBLISHERS OF SCIENTIFIC WORKS,
KING WILLIAM STREET, STRAND.
[Illustration: GIDEON ALGERNON MANTELL, L.L.D. F.R.S
_Vice-President of the Geological Society &c. &c._]
THOUGHTS
ON A
PEBBLE,
OR,
A FIRST LESSON IN GEOLOGY.
BY THE AUTHOR OF "THE WONDERS OF GEOLOGY."
[Illustration: _The Nautilus and the Ammonite._ _Vide_, p. 57.]
"There is no picking up a pebble by the brook-side, without finding all
nature in connexion with it."
_Contemplations of Nature._
EIGHTH EDITION; WITH THIRTY-TWO ILLUSTRATIONS.
LONDON:
REEVE, BENHAM, AND REEVE, KING WILLIAM STREET, STRAND.
1849.
TO
MY SON,
=Reginald Nebille Mantell, C.E.,=
THESE
"THOUGHTS ON A PEBBLE"
ARE MOST AFFECTIONATELY
INSCRIBED.
LONDON,
19, CHESTER SQUARE, PIMLICO.
1849.
"Every grain of sand is an immensity--every leaf a world--every insect
an assemblage of incomprehensible effects in which reflection is lost."
Lavater.
"To the natural philosopher there is no natural object that is
unimportant or trifling. From the least of Nature's works he may learn
the greatest lessons. The fall of an apple to the ground may raise his
thoughts to the laws which govern the revolutions of the planets in
their orbits; or the situation of a _pebble_ may afford him evidence of
the state of the globe he inhabits, myriads of ages before his species
became its denizens."
Sir J. F. W. Herschel.
TO THE READER.
Deeply impressed with the conviction that it is of the highest
importance the young and inquiring mind should have a correct idea
of natural phenomena--that it should not be left to its own unaided
efforts to unravel the mysteries of the beautiful world in which this
first state of being is destined to be passed--or have its curiosity
stifled or misled by unsatisfactory or erroneous conjectures--I have
endeavoured in this little work to explain in a simple and attractive
guise, some of the grand truths relating to the ancient physical
history of our planet, which modern geology has established.
The favourable reception of these desultory "_Thoughts_" which
were originally penned for the amusement and instruction of an
intelligent boy, is a gratifying proof that the attempt has not been
unsuccessful; and I would fain indulge the hope, that this "_First
Lesson in Geology_" may still be productive of good, by exciting in
some youthful minds a desire for the acquisition of natural knowledge;
and inculcating the important truth, that He who formed the Universe
has created nothing in vain; that His works all harmonize to blessings
unbounded by the mightiest or most minute of His creatures; and that
the more our knowledge is increased, and our powers of observation are
enlarged, the more exalted will be our conception of His wondrous works.
Chester Square,
Pimlico.
CONTENTS.
Page.
Thoughts on a Pebble: Part I. 5
More Thoughts on a Pebble: Part II. 33
"The Nautilus and the Ammonite" 57
Supplementary Notes 61
Note I. _Shells in Chalk_ 61
---- II. _Wood in Flint_ 66
---- III. _Whitby Ammonites_ 69
---- IV. _Fossil Nautili_ 72
---- V. _Brighton Cliffs_ 75
---- VI. _Rotaliæ in Chalk and Flint_ 79
---- VII. _Isle of Wight Pebbles_ 82
---- VIII. _Zoophytes of the Chalk_ 87
---- IX. _Minute Corals from the Chalk_ 92
---- X. _Infusorial Earths_ 97
LIGNOGRAPHS.
Page.
1. Vignette of Title-page.
2. Fossil Turban-echinus (_Cidaris_), with spines. 9
3. Bivalve with spines (_Plagiostoma spinosum_) in
chalk; from Lewes. 11
4. Teeth of several species of the Shark tribe, in
chalk; from Lewes. 12
5. Chalk-dust highly magnified, consisting of minute
shells. 13
6. Shells (_Rotaliæ_) from the chalk, highly magnified. 14
7. Ammonite (_A. communis_) from the Lias, at Whitby. 20
8. Nautilus (_N. elegans_) from the chalk-marl, Lewes. 22
9. View of the Cliffs east of Brighton. 27
10. Fossil animalcules (_Xanthidia_) in flint. 35
11. _Xanthidium palmatum_, in flint. 37
12. Rotalia in flint. 39
13. Minute scales of fishes in flint. 40
14. Choanites from the chalk; near Lewes. 44
15. A branch of fossil coral attached to the pebble 46
16. Coral-polype in flint. 47
17. Minute Corals from chalk. 50
18. Fossil cases or shields of animalcules from
Richmond, Virginia; highly magnified. 53
19. Several species of Lamp-shells (_Terebratulæ_) from
the chalk, near Brighton. 63
20. Silicified Oyster from the chalk. 65
21. Coniferous wood in flint, from Lewes Priory. 68
22. Several species of Ammonite. 69
23. The body of a recent microscopic animalcule
(_Nonionina_), the shell having been removed by
immersion in acid. 81
24. A branch of Sponge in flint; a minute Coral from
chalk; and a section of a pebble enclosing a
zoophyte (_Siphonia Morrisiana_). 85
25. Flints deriving their shapes from Zoophytes
(_Ventriculites_). 89
26. Ventriculites in chalk; from Lewes. 90
27. Portions of three kinds of recent corals. 94
LITHOGRAPHS.
Page.
Plate I. A rolled flint pebble, having a Choanite as a
nucleus, and the remains of an echinus and spine,
shell, and coral, apparent on the surface. 5
Plate II. A longitudinal section of the pebble, showing
the structure of the enclosed _Choanite_. 42
Plate III. A polished section of an Ammonite, having
the septa or chambers filled with variously coloured
spar, &c. 70
Plate IV. Polished sections of two pebbles from the
Isle of Wight; in the upper specimen, the transition
from opaque flint to cloudy chalcedony and
transparent quartz crystals, is beautifully shown;
the lower specimen is richly tinted; the dark
appearance is derived from manganese. 86
[Illustration: _Plate I._
"THE PEBBLE"
_Page 5_]
THOUGHTS
ON A
PEBBLE.
"Honoured, therefore, be thou, thou small pebble, lying in the lane;
and whenever any one looks at thee, may he think of the beautiful and
noble world he lives in, and all of which it is capable."
Leigh Hunt's _London Journal_, p. 10.
PART I.
Well might our immortal Shakspeare talk of "_Sermons in stones_;" and
Lavater exclaim, that "_Every grain of sand is an immensity_" and the
author of 'Contemplations of Nature' remark, that "_there is no picking
up a pebble by the brook-side without finding all nature in connexion
with it._"
I shall confine my remarks to a _flint_ pebble, as being the kind of
stone familiar to every one. The pebble I hold in my hand was picked
up in the bed of the torrent which is dashing down the side of yonder
hill, and winding its way through that beautiful valley, and over those
Huge rocks and mounds confus'dly hurl'd.
The fragments of an earlier world,
which partially filling up the chasm, and obstructing the course of
the rushing waters, give rise to those gentle murmurings that are so
inexpressibly soothing and delightful to the soul.
[Sidenote: ORIGIN OF THE PEBBLE.]
Upon examining this stone I discover that it is but the fragment of a
much larger mass, and has evidently been transported from a distance,
for its surface is smooth and rounded, the angles having been worn
away by friction against other pebbles, produced by the agency of
running water. I trace the stream to its source, half way up the hill,
and find that it gushes out from a bed of gravel lying on a stratum of
clay, which forms the eminence where I am standing, and is nearly 300
feet above the level of the British Channel. From this accumulation of
water-worn materials the pebble must have been removed by the torrent,
and carried down to the spot where it first attracted our notice; but
we are still very far from having ascertained its origin. The bed of
stones on the summit of this hill is clearly but a heap of transported
gravel--an ancient sea-beach or shingle--formed of chalk-flints, that
at some remote period were detached from their parent rock, and
broken, rolled, and thrown together, by the action of the waves. We are
certain of this because we know that flints cannot grow;[A] that they
were originally formed in the hollows or fissures of other stones; and
upon inspecting the pebble more attentively, we perceive, not only that
such was the case, but also that it has been moulded in _Chalk_, for it
contains the remains of certain species of extinct shells and corals,
which are found exclusively in that rock. Here then a remarkable
phenomenon presents itself for our consideration; this flint, now so
hard and unyielding, must once have been in a soft or fluid state,
for the delicate markings of the case and spine of an _Echinus_, or
Sea-Urchin, are deeply impressed on its surface;[B] and a fragile shell
with its spines, is partially imbedded in its substance.[C] Nay more,
upon breaking off one end of the pebble,[D] we find that a sponge, or
some analogous marine zoophyte, is entirely enveloped by the flint;
and also that there are here and there portions of minute corals, and
scales of fishes. What a "_Medal of Creation_" is here--what a page of
nature's volume to interpret--what interesting reflections crowd upon
the mind!
[A] "_Flints cannot grow._"--Here I would digress for a moment to
notice an opinion so generally prevalent, that perhaps some of my
young readers will not be prepared at once to answer the question--_Do
stones grow?_ The farmer who annually ploughs the same land, and
observes a fresh crop of stones every season, will probably reply in
the affirmative; and the general observer who has for successive years
noticed his gardens and plantations strewn with stones, notwithstanding
their frequent removal, may possibly entertain the same opinion; but
a little reflection will show that stones cannot be said to grow or
increase, in the proper acceptation of the term. Animals and plants
grow, because they are provided with vessels and organs by winch they
are capable of taking up particles of matter and converting them
into their own substance; but an inorganic body can only increase in
bulk by the addition of some extraneous material; hence stones may
become incrusted, or they may be cemented together and form a solid
conglomerate, but they possess no inherent power by which they can
increase either in size or number--_they cannot grow_.
[B] Plate I, _a_.
[C] Plate I, _b_.
[D] Plate I, _c_.
[Sidenote: FOSSIL ECHINUS WITH SPINES.]
[Illustration: Lign. 2:--Fossil Turban Echinus, with its
spines; in limestone.
(See '_Medals of Creation_', p. 340.)]
[Sidenote: FOSSIL SHELLS IN CHALK.]
[Illustration: Lign. 3:--Shell with spines, imbedded in Chalk;
from Lewes. (See '_Medals of Creation_,' 1 p. 390.)]
To avoid confusion, we will reverse the order of our inquiry, and first
contemplate the formation of the flint in its native rock. The Chalk,
that beautiful white stone, which (as an American friend, who saw it
for the first time, observed), is so like an artificial production,
abounds in marine shells and corals, and in the remains of fishes,
crabs, lobsters, and reptiles, all of which differ essentially from
living species; although a few of the corals and shells resemble, in
some particulars, certain kinds that inhabit the seas of hot climates.
These remains are found in so perfect a state--the shells with all
their spines and delicate processes (_Lign. 3_), and the fishes with
their teeth (_Lign, 4_), scales, and fins, entire--that no doubt can be
entertained of the animals having been surrounded by the chalk while
living in their native sea, and that many of them were entombed in
their stony sepulchres suddenly, when the rock was in the state of mud,
or like liquid plaster of Paris.[E]
[E] See Note I. _Shells in the Chalk._
[Illustration: Lign. 4:--Fossil teeth of Fishes of the Shark
family, in Chalk; from Lewes. (See '_Medals of Creation_.' p. 625.)]
[Sidenote: SHELLS AND FISHES IN CHALK.]
But besides the fossils which are obvious to the unassisted eye, the
Chalk teems with myriads of minute forms that may readily be detected
with a lens of moderate power; and even when these have been extracted,
the residue, which appears to be merely white calcareous earth, is
found, when examined under the microscope, to consist almost wholly of
bodies yet more infinitesimal--of perfect shells and corals, so minute,
that a cubic inch of chalk may contain upwards of a million of these
organic remains (see _Lign. 5_)!
[Illustration: Lign. 5:--A few grains of Chalk-dust highly
magnified, and shown to consist of shells, &c.
_a, a_, Shells called Rotalia.
_b_, ------------- Textularia.
(See '_Medals of Creation_,' p. 232.)
]
The Chalk is stratified--that is, divided into _strata_ or layers--as
if a certain quantity of mud had sunk to the bottom of the sea, and
enveloped the shells, corals, &c., which fell in its way, and had
become somewhat solid before another layer was deposited upon it.
[Sidenote: FLINT NODULES AND VEINS.]
The mineral substance termed _silex_ or _flint_, is variously
distributed in the chalk. It most commonly occurs in the state of
nodules of an irregular or spheroidal, globular figure, which are
arranged in rows parallel and alternating with, the cretaceous strata;
it is likewise disposed in continuous thin layers, which are spread
over considerable areas; and it often forms horizontal, vertical, and
oblique veins, that fill up the fissures and interstices of the chalk.
The siliceous nodules frequently enclose corals, shells, sponges,
and other organic remains, as in the pebble before us; and in many
instances these fossils are found partly imbedded in the chalk and
partly invested with flint. But though flints contain in abundance
relics of the same species of marine animals as the chalk, they are not
like that rock composed of an aggregation of fossil remains; on the
contrary, the siliceous earth, which is their constituent substance,
was evidently once in a state of complete solution in water, and
precipitated into the chalk before the latter was consolidated, the
organic bodies serving as nuclei or centres around which the silex
concreted; for the deposition of the flint, like that of the chalk,
appears to have taken place periodically.[F]
[F] Note II. _Wood in flint._
[Illustration: Lign. 6:--Minute fossil shells from Flint and
Chalk, very highly magnified, and seen by transmitted light.
1, 2, 3, 6, Rotaliæ;
4, Portion of a Nautilus;
5, Rotalia composed of flint.
(See '_Medals of Creation_,' p. 232.)
]
[Sidenote: ANIMALCULES IN CHALK.]
The composition of the Chalk, and the prevalence throughout that rock
of the relics of animals that can only live in salt-water, prove
incontestably that the chalk and flint were deposited in the sea;
and that our beautiful South Downs, now so smooth and verdant, and
supporting thousands of flocks and herds, and the rich plains and
fertile valleys spread around their flanks, were once the bed of an
ocean. It is also evident not only that such must have been the case,
but also that the Chalk was deposited in the basin of a very _deep_
sea--in the profound abyss of an ocean as vast as the Atlantic.
[Sidenote: AMMONITES AND NAUTILI.]
From the absence of gravel, shingle, and sea-beach, it is certain that
the white chalk-strata were formed at a great distance from sea-shores
and cliffs; and this inference is confirmed by the swarms of shells
termed _Ammonites_ and _Nautili_, which we know from their peculiar
structure were, like the recent pearly Nautilus, inhabitants of deep
waters only. For these are chambered shells; that is, are divided
internally by thin transverse shelly septa or plates, into numerous
cells; the body of the animal occupied only the outer compartment,
but was connected with the entire series of chambers by a tube or
siphuncle, which passed through each partition. This mechanism
constituted an apparatus which contributed to the buoyancy of these
animals when afloat on the waves; for the Ammonites and Nautili were
able to swim on the surface, or sink to the depths of the ocean at
pleasure.
The fragile Nautilus that steers his prow,
The sea-born sailor of his shell canoe,
The Ocean Mab, the fairy of the sea,
O'er the blue waves at will to roam is free.
He, when the lightning-winged tornadoes sweep
The surf, is safe, his home is in the deep;
And triumphs o'er the Armadas of mankind,
Which shake the world, yet crumble in the wind.
Byron, _The Island_.
[Sidenote: WHITBY SNAKE-STONES.]
[Illustration: Lign. 7:--Ammonite from Whitby.]
The Ammonites, so called from the supposed resemblance of their shells
to the fabled horn of Jupiter Ammon, are only known in a fossil state;
but they must have swarmed in the ancient seas, for several hundred
species have been discovered in the Chalk and antecedent strata, though
none have been found in any deposits of more recent formation; at the
termination of the chalk epoch the whole race, therefore, appears to
have perished. The Ammonites are commonly termed _snake-stones_, from
the origin ascribed to them by local legends; those of Whitby are well
known (see _Lign. 7_).[G]
[G] Note III. _Whitby Ammonites._
Thus Whitby's nuns exulting told--
How that of thousand snakes, each one
Was changed into a coil of stone,
When holy Hilda prayed:
Themselves, within their sacred bound,
Their stony folds had often found.
Scott's _Marmion_.
[Illustration: Lign. 8:--Nautilus from the Chalk, near Lewes,
(one-eighth the natural size.)]
The Nautili were the contemporaries of the Ammonites, and many kinds
are found associated with those shells, in strata far more ancient than
the Chalk; and several species of both genera, as we have previously
shown, were inhabitants of the cretaceous ocean. When the Ammonites
became extinct, the Nautili continued to flourish, and numerous
examples occur in the strata that were deposited during the vast period
which intervened between the close of the Chalk formation, and the
dawn of the existing condition of the earth's surface. At the present
time two or three kinds only are known in a living state, and these are
restricted to the seas of tropical climes, and so seldom approach the
shores, that but few specimens of the animals that inhabit the shells
have been obtained.
The Nautilus, therefore, is one of those types of animal organization
that have survived all the physical revolutions to which the surface of
the earth was subjected during the innumerable ages that preceded the
creation of the human race.[H] This remarkable fact is portrayed with
much force and beauty by Mrs. Howitt, in the following stanzas:
[H] Note IV. _Fossil Nautili._
TO THE NAUTILUS.
Thou didst laugh at sun and breeze
In the new created seas;
Thou wast with the reptile broods
In the old sea solitudes,
Sailing in the new-made light,
With the curled-up Ammonite.
Thou surviv'dst the awful shock,
Which turn'd the ocean-bed to rock;
And chang'd its myriad living swarms
To the marble's veined forms.
Thou wert there, thy little boat,
Airy voyager! kept afloat,
O'er the waters wild and dismal,
O'er the yawning gulfs abysmal;
Amid wreck and overturning,
Rock-imbedding, heaving, burning,
Mid the tumult and the stir,
Thou, most ancient mariner!
In that pearly boat of thine,
Sail'dst upon the troubled brine.
[Sidenote: THE SEA-SHORE.]
We have thus acquired satisfactory proof that the flint of which our
pebble is composed, was once fluid in an ocean teeming with beings, of
genera and species unknown in a living state, and that it consolidated
and became imbedded in the chalk, which was then being deposited at
the bottom of the sea; hence the shells, corals, and other organic
remains, which we now find attached to its surface, and enclosed in
its substance. Thus much for the origin of the pebble; let us next
inquire by what means it was dislodged from its rocky sepulchre, cast
up from the depths of the ocean, and transported to the summit of the
hill whence it was dislodged by yonder torrent. If we stroll along the
sea-shore, and observe the changes which are there going on, we shall
obtain an answer to these questions; for
There is a _language_ by the lonely shore--
There is society where none intrudes,
By the deep Sea, and music in its roar!
Byron.
The incessant dashing of the waves against the base of the
chalk-cliffs, undermines the strata, and huge masses of rock are
constantly giving way and falling into the waters. The chalk then
becomes softened and disintegrated, and is quickly reduced to the state
of mud, and transported to the tranquil depths of the ocean, where it
subsides and forms new deposits; but the flints thus detached, are
broken and rolled by attrition into the state of boulders, pebbles, and
gravel, and ultimately of sand.
[Illustration: Lign. 9:--View of Brighton Cliffs; looking
eastward from Kemp Town.[I]
_a. Cliff's composed of chalk rubble._
_b. Ancient elevated sea-beach._
_c. Chalk forming the base of the Cliffs._
]
[I] Note V. _Brighton Cliffs._
[Sidenote: BRIGHTON CLIFFS.]
Now we must bear in mind, that had the chalk remained at the bottom of
the deep sea in which it was originally deposited, it would not have
been exposed to these destructive operations. It is therefore manifest,
that at some very distant period of the earth's physical history, the
bed of the Chalk-ocean was broken up, extensive areas were protruded
above the waters, lines of sea-cliffs were formed, and boulders, sand,
and shingle accumulated at their base. Subsequent elevations of the
land took place, and finally, the sea-beach was raised to its present
situation, which is several hundred feet above the level of the sea!
Every part of the earth's surface presents unequivocal proofs that the
elevation of the bed of the ocean in some places, and the subsidence
of the dry land in others, have been, and are still, going on; and
that, in truth, the continual changes in the relative position of the
land and water, are the effects of laws which the Divine Author of
the Universe has impressed on matter, and thus rendered it capable of
perpetual renovation:--
Art, Empire, Earth itself, to change are doomed;
Earthquakes have raised to heaven the humble vale,
And gulfs the mountain's mighty mass entombed,
And where the Atlantic rolls wide continents have bloomed.
Beattie.
[Sidenote: IMMUTABILITY OF THE SEA.]
Our noble poet, Lord Byron, in his sublime apostrophe to the Sea,
has most eloquently enunciated the startling fact revealed by modern
geological researches,--namely, that if the character of immutability
be attributable to anything on the surface of our planet, it is to the
ocean and not to the land!--
Roll on, thou deep and dark blue ocean--roll!
Ten thousand fleets sweep over thee in vain;
Man marks the earth with ruin--his controul
Stops with the shore:--upon the watery plain
The wrecks are all thy deed, nor doth remain
A shadow of man's ravage, save his own.
When, for a moment, like a drop of rain.
He sinks into thy depths with bubbling groan,
Without a grave, unknell'd, uncoffin'd, and unknown!
Thy shores are empires, changed in all save thee,--
Assyria, Greece, Rome, Carthage, what are they?
Thy waters wasted them while they were free,
And many a tyrant since; their shores obey
The stranger, slave, or savage,--their decay
Has dried up realms to deserts:--not so thou,
Unchangeable, save to thy wild waves' play--
_Time writes no wrinkle on thine azure brow:_
_Such as Creation's dawn beheld, thou rollest now!_
Thou glorious mirror, where the Almighty's form
Glasses itself in tempests; in all time,
Calm or convulsed--in breeze, or gale, or storm,
Icing the Pole, or in the torrid clime
Dark-heaving, boundless, endless, and sublime--
The image of Eternity--the throne
Of the Invisible; even from out thy slime
The monsters of the deep are made; each zone
Obeys thee: thou goest forth, dread, fathomless, alone!
Childe Harold. _Canto IV._
[Sidenote: APOSTROPHE TO THE OCEAN.]
I will conclude this "first lesson" with the following beautiful
remark of an eminent living philosopher:[J]--"To discover order and
intelligence, in scenes of apparent wildness and confusion, is the
pleasing task of the geological inquirer; who recognises, in the
changes which are continually taking place on the surface of the globe,
a series of necessary operations, by which the harmony, beauty, and
integrity of the Universe are maintained and perpetuated; and which
must be regarded, not as symptoms of frailty or decay, but as wise
provisions of the Supreme Cause, to ensure that circle of changes, so
essential to animal and vegetable existence."
[J] Dr. Paris.
[Illustration]
MORE THOUGHTS
ON A
PEBBLE.
"Not a mote in the beam, not an herb on the mountain, not a pebble
on the shore, not a seed far-blown into the wilderness, but contributes
to the lore that seeks in all the true principle of life--the
beautiful--the joyous--the immortal."
Sir E. Bulwer Lytton's _Zanoni_.
PART II.
More thoughts on a pebble!--is not the subject exhausted? have not
all the hieroglyphics impressed on the flint been interpreted?--can
Science, like the fabled wand of the magician, call forth from the
stone and from the rock their hidden lore, and reveal the secrets they
have so long enshrined?--Gentle Reader! but one page of the eventful
history of the pebble has been deciphered; I proceed to transcribe this
natural record of the past, explain its mysterious characters, and
present to thy notice the marvels they disclose.
Our previous examination of the specimen showed that the flint had
once been in a fluid state, and had consolidated in a sea inhabited by
shells, echini, fishes, corals, sponges, and other zoophytes; and the
appearance of the fractured end (_Plate I, c_), indicated that some
organic body had formed the nucleus of the pebble, and that traces of
the structure of the original still remained. To ascertain if this
inference is correct, it will be necessary to divide the stone in a
longitudinal direction--but I will first strike off a small fragment,
and examine it by the aid of a microscope.
[Sidenote: FOSSIL ANIMALCULES.]
[Illustration: Lign. 10:--Fossil animalcules (_Xanthidia_) in
Flint.]
By a sharp blow of a hammer, a very thin and minute portion of the
flint has been detached (see _Lign. 10, fig. 1_); it is translucent,
and when held between the eye and a strong light, appears like a slice
of horn; and a few extremely minute specks may with difficulty be
detected. Under the microscope, five of these almost invisible points
are well defined, and present a radiated appearance (see _fig. 3_); but
I will substitute a higher power, and lo! they are seen to be distinct
globular or spherical bodies beset with spines (_fig. 3_); and with a
still more powerful lens, one which magnifies many hundred times, their
nature is completely displayed. The whole five possess this general
character--a central globular case or shell, from which radiate tubes
or hollow spines, that terminate in fringed or divided extremities
(_figs. 4, 5, 6_); but these bodies differ from each other in the
relative proportions of the shell and spines, and in the number,
shape, and length of the tubular appendages. The group, in short, is
separable into three distinct species, of the same kind of fossil
remains; and several other varieties occur in the chalk and flint. .
[Sidenote: XANTHIDIA IN FLINT.]
[Illustration: Lign. 11:--_Xanthidium palmatum_ in flint:
highly magnified.]
But what are these bodies?--They are the durable cases of animalcules,
many species of which swarm in our seas, and are so minute, that
thousands may be contained in a drop of water! In a living state,
the case is flexible and filled with a granular jelly, which is the
soft body of the animalcule, and the tubes and the outer surface are
invested with a similar substance. After death the soft parts dissolve;
but the case and its spines often remain unchanged.
In another magnified portion of the pebble, a specimen of the
microscopic discoidal shells which we have already seen compose the
greater part of the white chalk (_Lign. 5_, p. 14), is beautifully
displayed when viewed by transmitted light, under a highly magnifying
power (_Lign. 12_).[K] Our investigation has thus shown, that a great
part of the pebble is actually composed of the aggregated fossil
remains of animalcules, so minute as to elude our unassisted vision,
but which the magic power of the microscope reveals to us, preserved,
like flies in amber, in all their original sharpness of outline and
delicacy of structure.
[K] Note VI. _Rotaliæ in chalk and flint._
[Sidenote: ROTALIA IN FLINT.]
[Illustration: Lign. 12:--Rotalia in flint: highly magnified.]
On another fragment of this stone two glittering specks, not larger
than a pin's head, are discernible (_Lign. 9_): these with a magnifier
of moderate power, are seen at a glance to be scales of fishes. But
they differ from each other; both have the surface smooth, and without
enamel: in the one the margin or edge is simple (_fig. 3_); in the
other, it is divided like the teeth of a comb (_fig. 2_);--trifling as
this difference may appear, it is sufficient to enable the naturalist
to determine that the fishes which furnished these scales belonged to
two distinct orders, of which the Salmon and the Mullet are living
examples.
[Illustration: Lign. 13:--Scales of Fishes in flint.
Fig. 1.--A fragment of the pebble with the scales of the natural size.
2.--One of the Scales (of a species of _Beryx_) highly magnified.
3.--The other Scale (of a species of _Salmo_).
]
[Illustration: _Plate II._
_Longitudinal section of the Pebble._
_Page 41._]
[Sidenote: SECTION OF THE PEBBLE.]
SECTION OF THE PEBBLE.
_Plate II._
We will now avail ourselves of the assistance of the lapidary, and
divide the pebble in a longitudinal direction;--what a beautiful and
interesting section is thus obtained! The markings observable on the
fractured portion of the stone (see Plate I, c), are thus
shown to have originated, as we surmised, from some organic body,
which the flint, when fluid, had penetrated and enveloped. The enclosed
fossil was obviously one of those soft marine zoophytes, allied to the
_Actiniæ_ or _Sea-Anemones_, which are of a globular, spherical, or
inversely conical shape, and consist of a tough, jelly-like substance,
permeated with tubes, disposed in a radiated manner around a central
cavity, or digestive sac; a structure admitting of that constant supply
and circulation of sea-water, which the economy of these curious forms
of animal existence requires.
[Sidenote: ISLE OF WIGHT PEBBLES.]
The surface exposed by the division of the pebble, is an oblique
vertical section of the petrified zoophyte. It shows a central canal
filled with bluish-grey flint (_Plate II, c_), in a mass traversed by
tubes or channels, which possess considerable beauty and variety of
colour from an impregnation of iron.[L] A transverse section (see
_Lign. 14._ fig. 1) would, of course, have a central spot, with rays
proceeding thence to the circumference, as in the oblique fracture
(_Plate I, c_).[M]
[L] Specimens of this kind form beautiful objects when polished, and
are mounted as brooches by the lapidaries of Brighton, Bognor, and
the Isle of Wight, who term them petrified sea-animal flowers. Mr. G.
Fowlstone (4, Victoria Arcade) of Ryde, has many splendid examples, and
also agates and jaspers, the genuine productions of the Island.
[M] Note VII. _Isle of Wight Pebbles._
[Sidenote: CHOANITES KONIGI.]
The form of the original zoophyte when living, must have been that of
an inverted cone or funnel, (hence the scientific name _Choanite_ or
funnel-like,) with a long cylindrical digestive cavity in the centre,
from which tubes ramified through every part of the mass. It was
attached to a rock, stone, or shell, by root-like fibres which spread
out from its base; and its soft body was strengthened, as is the case
in many sponges and animals of a similar nature, by numerous siliceous
spines or spicula, which are often found in the flint and chalk (see
_Lign. 10._ fig. 5).[N]
[N] Note VIII. _Zoophytes of the Chalk._
[Illustration: Lign. 14:--Choanites _Konigi_: from
the Chalk.
Fig. 1.--A transverse section.
2.--Upper portion of the body.
3.--Vertical section, like the pebble, Pl. II. p. 41.
4.--A flint, enclosing a Choanite, which is exposed on the
upper surface.
5.--Various forms of siliceous spines of Choanites and other
analogous bodies; magnified slightly.
(See '_Medals of Creation_,' p. 264.)
]
The _Choanites_ must have swarmed in the Chalk ocean, for in some of
the strata almost every flint exhibits traces of these zoophytes.[O]
[O] The shingle at Brighton and Bognor in Sussex, and in various
localities in the Isle of Wight, abounds in specimens more or less
perfect. I would inform my fair readers who may visit these places, and
be inclined to purchase a brooch, in illustration of these "_Thoughts
on a Pebble_," that by far the greater number of the so-called
Brighton and Isle of Wight moss-agates, jaspers, &c., sold by the
lapidaries and jewellers, are of German or Scotch origin; and that the
_false-emeralds_, and _aquamarines_, are water-worn fragments of common
green glass bottles!
[Sidenote: CORALS IN CHALK.]
[Illustration: Lign. 15:--Branch of Coral on the
Pebble.
Fig. 1.--A portion magnified.
2.--A fragment represented as when alive.
_a, a_, Two polypes collapsed.
_b, b_, Two polypes with their tentacula extended.
]
One more character inscribed on the pebble remains to be interpreted;
it is the minute branch of coral partially imbedded in the flint.[P]
The surface of this coral, when seen with a powerful lens, is found to
be studded with small pores or cells. In a recent state, each cell was
inhabited by a living polype or animalcule, which, though permanently
united at its base to the general mass, had an independent existence,
and possessed sensation and voluntary motion; expanding its thread-like
feelers or tentacula to catch its prey, and withdrawing, at will, into
its little cell.[Q]
[P] Plate I. immediately below the shell and spine of Echinus.
[Q] For a popular account of recent and fossil corals, see 'Wonders of
Geology,' 6th Edit., vol. ii. Lecture VI. p. 589.
[Illustration: Lign. 16:--A Coral-polype preserved in flint:
magnified 500 diameters.]
From these investigations, we learn that the Pebble, which has formed
the subject of our contemplation, had its origin in a living zoophyte
that was growing on a rock, in a sea whose boundaries have long since
been swept away; that corals, shells, and echini inhabited the bottom
of the deep; and that fishes related to existing families, sported in
the waters of that ancient ocean. In fine, we have presented to us the
scene so exquisitely described by the American poet:--
[Sidenote: THE CORAL GROVE.]
THE CORAL GROVE.
Deep in the waves is a coral grove.
Where the purple mullet and gold fish rove,
Where the sea-flower spreads its leaves of blue,
That never are wet with the falling dew.
But in bright and changeful beauty shine,
Far down in the green and glassy brine.
The floor is of sand, like the mountain drift.
And the pearl-shells spangle the flinty snow;
From coral rocks the sea-plants lift
Their boughs, where the tides and billows flow;
The water is calm and still below.
For the winds and the waves are absent there,
And the sands are bright as the stars that glow
In the motionless fields of upper air:
There with its waving blade of green,
The sea-flag waves through the silent water,
And the crimson leaf of the dulse is seen.
To blush like a banner bathed in slaughter.
There with a light and easy motion
The fan-coral sweeps through the clear deep sea;
And the yellow and scarlet tufts of ocean,
Are bending like corn on the upland lea;
And life in rare and beautiful forms,
Is sporting amidst those bowers of stone.
Percival.
[Illustration: Lign. 17:--Minute Corals from the Chalk;[R]
_highly magnified_.]
[R] Note IX. _Minute corals from the Chalk._
[Sidenote: MICROSCOPIC CORALS.]
Our previous examination of the pebble had prepared us for these
results; but the microscope, that mighty talisman of wisdom, has shown
us, that even those infinitesimal creatures to whom a drop of water
is an unbounded ocean--those living atoms of that world of being which
is for ever concealed from the uninstructed mind--the inhabitants of
that universe beneath us, which the eye of science can alone penetrate,
existed in ages incalculably remote, and were, like their gigantic
contemporaries, the living instruments by which a large proportion
of the solid materials of the surface of our planet was elaborated;
their imperishable siliceous and calcareous skeletons, constituting no
inconsiderable amount of the crust of the earth.[S]
[S] See _"Thoughts on Animalcules, or a Glimpse of the Invisible World
revealed by the Microscope_," by the Author. Published by Mr. Murray,
London, 1846.
Fossil animalcules and corals similar to those we have discovered in
the pebble and in the chalk, and hundreds of other genera and species
equally minute, occur in such prodigious numbers, as to warrant the
conclusion, that this class of animal existence has contributed more
largely than any other, to the formation of the sedimentary strata.
Not only the Chalk hills, but whole mountain-ranges formed of other
deposits of great thickness and extent, are found to consist almost
entirely of similar remains. In the state of rock, of sand, of clay,
of marl--in the coarsest limestone, and in the purest crystal, the
petrified skeletons of animalcules alike abound. The town of Richmond,
in Virginia, is built on a bed of stone twenty feet thick, which is
wholly composed of the fossil skeletons of different kinds of marine
animalcules. The polishing slate of Bilin, in Germany, is wholly made
up of the siliceous shields of similar beings, disposed in layers
without any connecting medium; and these belong to species so minute,
and are so closely compressed together, that in a cubic inch of the
stone, weighing but two hundred and twenty grains, there are the
remains of _forty-one thousand millions_ of animalcules![T]
[T] See '_Medals of Creation_,' p. 221.
[Illustration: Lign. 18:--Animalcules from the Richmond earth:
very highly magnified[U]]
[U] Note X. _Richmond Infusorial earth._
* * * * *
[Sidenote: REFLECTIONS.]
Here we must bring our "_Thoughts on a Pebble_" to a close; but not
without adverting to the pure and elevating gratification which
investigations of this nature afford, and the beneficial influence
they exert upon the mind and character. In circumstances where the
uninstructed and incurious eye can perceive neither novelty nor beauty,
he who is imbued with a taste for natural science will everywhere
discover an inexhaustible mine of pleasure and instruction, and new
and stupendous proofs of the power and goodness of the Eternal! For
every rock in the desert, every boulder on the plain, every pebble by
the brook-side, every grain of sand on the sea-shore, is fraught with
lessons of wisdom to the mind which is fitted to receive and comprehend
their sublime import.
"From millions take thy choice,
In all that lives a guide to God is given;
Ever thou hear'st some guardian angel's voice,
When nature speaks of heaven!"
Amidst the turmoil of the world and the dreary intercourse of common
life, we possess in these pursuits a never-failing source of delight,
of which nothing can deprive us--an oasis in the desert, to which
we may escape, and find a home "wherever the intellect can pierce,
and the spirit can breathe the air."[V] For like the plant which the
Prophet threw into the waters of Marah,[W] that changed the bitterness
of the wave into sweetness, a branch from the tree of knowledge thrown
into the turbid stream of life, purifies its waters, and imparts to
them a healing virtue, which sheds a hallowing and refreshing influence
over the soul!
[V] Sir E. Bulwer Lytton.
[W] Exod. XV. 23.
THE
NAUTILUS and the AMMONITE.
(_See Page 22._)
FROM SKETCHES IN PROSE AND VERSE,
By the late G. F. Richardson, Esq.
The Nautilus and the Ammonite
Were launch'd in storm and strife;
Each sent to float, in its tiny boat,
On the wide, wild sea of life.
And each could swim on the ocean's brim,
And anon, its sails could furl;
And sink to sleep in the great sea deep,
In a palace all of pearl.
And their's was a bliss, more fair than this,
That we feel in our colder time;
For they were rife in a tropic life,
In a brighter, happier clime.
They swam 'mid isles, whose summer smiles
No wintry winds annoy;
Whose groves were palm, whose air was balm.
Where life was only joy.
They roam'd all day, through creek and bay,
And travers'd the ocean deep;
And at night they sank on a coral bank,
In its fairy bowers to sleep.
And the monsters vast, of ages past.
They beheld in their ocean caves;
And saw them ride, in their power and pride,
And sink in their billowy graves.
Thus hand in hand, from strand to strand,
They sail'd in mirth and glee;
Those fairy shells, with their crystal cells,
Twin creatures of the sea.
But they came at last, to a sea long past,
And as they reach'd its shore,
The Almighty's breath spake out in death,
And the Ammonite liv'd no more.
And the Nautilus now, in its shelly prow,
As o'er the deep it strays,
Still seems to seek, in bay and creek,
Its companion of other days.
And thus do we, in life's stormy sea,
As we roam from shore to shore;
While tempest-tost, seek the lov'd--the lost--
But find them on earth no more!
Geology, in the magnitude and sublimity of the objects of which it
treats, ranks next to Astronomy in the scale of the sciences.
Sir J. F. W. Herschel.
[Illustration]
SUPPLEMENTARY NOTES.
Note I. Page 13. _Shells in Chalk._
The shells of mollusca, in consequence of their durability, are the
most abundant fossils in the sedimentary strata;[X] entire layers
of marble and other limestone, of great thickness and extent, are
wholly composed of an aggregation of a few species or genera: in some
instances of fresh-water snails--as, for example, the Sussex and
Purbeck marbles;[Y] in others, of marine bivalves and univalves, as the
oyster-conglomerate of Bromley, and the shelly limestones of Portland,
Dorsetshire, &c.
[X] For an account of the geological value of fossil shells, see
'_Medals of Creation_,' vol. i. p. 363.
[Y] See '_Wonders of Geology_,' 6th Edition, p. 402.
The cretaceous strata contain many hundred species of bivalves and
univalves, by far the greater part of which belong to extinct genera;
and the species, with but four or five exceptions, are unknown in more
recent deposits. In loose sandy strata, fossil shells are oftentimes
beautifully preserved, and may be obtained in as perfect a condition
as if gathered from the sands on the sea-shores: such is the state of
the specimens which abound in the sandy clays near Barton in Hampshire,
and in the "_Crag_" of Essex and Suffolk. In certain beds of clay,
shells are also found entire; sometimes retaining the epidermis, and
the cartilaginous ligament of the hinge. The bivalves in the white
chalk are generally perfect; but the univalves, probably from the more
delicate structure of the originals, seldom retain any vestiges of the
shell, excepting portions of the internal nacreous coat adhering to the
chalk casts, which have been moulded in the interior of the shells.
[Illustration: Lign. 19:--Bivalve shells (_Terebratulæ_) from
Chalk (_natural size_).
1, 2. Plicated species. 1. _T. octoplicata._ 2. _T. subplicata._
3, 4. Smooth species. 3. _T. semiglobosa._ 4. _T. subrotunda._
]
[Sidenote: TEREBRATULÆ FROM CHALK.]
In some of the cretaceous strata several extinct species of _Oyster_,
_Scallop_, _Arca_, _Tellina_, and other well-known marine bivalves
abound; and with them are associated many genera of which no living
species have been observed. Among the bivalves that prevail in the
English chalk, are three or four kinds of _Terebratulæ_: which are
small, elegant, subglobular shells, belonging to a family of which
nearly 500 species, referable to several genera, have been obtained
from the British strata.[Z] Certain genera are restricted to the most
ancient sedimentary rocks, in which they occur in almost incredible
numbers; others have a wider range and are met with in the later
secondary deposits; while a few are found in the newest beds, and
have living representative species in the seas of warm climates. From
the immense antiquity of their lineage, these _Terebratulæ_ have been
humourously termed the "_fossil aristocracy_." Some of the most common
chalk species are figured of the natural size in _Lign. 19_. When
living the animal was attached to a rock or other body by means of a
_byssus_ or peduncle, exserted through the aperture in the beak or
curved extremity of the largest valve.[AA] The shells of the smooth
_Terebratulæ_ are full of minute holes or perforations, which may
readily be distinguished with a lens of moderate power.
[Z] See '_Wonders of Geology_,' 6th Edit. p. 329.
[AA] In the Conchological Gallery of the British Museum there is a
group of thirty or forty recent _Terebratulæ_ attached to a stone by
their peduncles; from Australia.
[Sidenote: PETRIFIED OYSTER.]
[Illustration: Lign. 20:--Oyster from the Chalk, near Brighton
(natural size).]
Occasionally the soft body of the mollusk completely silicified--that
is, transmuted into flint--is found in its natural position in the
shell. A beautiful example of this kind is represented in _Lign. 20_.
It is an extinct species of oyster: both valves were entire when I
removed the chalk and cleared the specimen; part of one valve has
been broken away to expose the petrified body of the animal. I have
seen a _Trigonia_[AB] from the oolite of Tisbury in Wiltshire, in
which the entire body of the mollusk was transformed into flint, and
the _branchiæ_ or lamellated gills were beautifully defined, though
converted into semi-transparent chalcedony.
[AB] _Trigonia:_ a genus of bivalves, of which there are many extinct
species in the chalk and oolite; some bands of Portland stone are an
aggregation of _Trigoniæ:_ a few very small species, inhabitants of the
seas of Australia and New Zealand, are the only known living forms of
this once prevailing type of mollusca. See '_Medals of Creation_,' p.
407.
Note II. Page 17. _Wood in Flint._
[Sidenote: WOOD IN FLINT.]
I would remind the reader that the white chalk, together with the
various strata of sand, clay, and limestone, comprising the cretaceous
formation of England, must be regarded as an ancient ocean-bed; in
other words, an accumulation of earthy sediments, formed in the
profound depths of the sea, in periods of long duration and of
incalculable antiquity, and more or less consolidated by subsequent
chemical and mechanical agency. These deposits are made up of organic
and inorganic materials: the former consist of the debris of the cliffs
and shores which encompassed the ancient ocean, of the spoils of the
land brought into the waters by floods and rivers, and of mineral
matter thrown down from chemical solutions. The organic substances
are the durable remains of the animals and plants which lived and
died in the sea, and of terrestrial and fluviatile species that were
transported from islands or continents by rivers and their tributaries.
The whole constitutes such an assemblage of strata as would probably be
presented to observation, if a mass of the bed of the Atlantic 2,000
feet in thickness, were elevated above the waters, and became dry land;
the only essential difference would be in the generic and specific
characters of the imbedded animal and vegetable remains.
The vestiges of terrestrial and fluviatile animals and plants found in
the chalk are comparatively but few: I have collected from Kent and
Sussex, bones of gigantic land lizards, (the _Iguanodon_), of flying
reptiles, (_Pterodactyles_), and of fresh-water Turtles, and water-worn
fragments of stems of coniferous trees allied to the _Araucaria_ or
Norfolk Island Pine; fruits or aments of coniferse; and stems and
foliage of plants related to the _Cycas_ and _Zamia_.
[Illustration: Lign. 21:--Fragment of coniferous wood in flint.]