THOUGHTS
ON A
PEBBLE

REEVE, BENHAM, AND REEVE,
PRINTERS AND PUBLISHERS OF SCIENTIFIC WORKS,
KING WILLIAM STREET, STRAND.

Painted by J. J. Masquerier.

Engraved by Samuel Stepney.

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."

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.

LIGNOGRAPHS.

LITHOGRAPHS.

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.

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].

FOSSIL ECHINUS WITH SPINES.

Lign. 2:—Fossil Turban Echinus, with its spines; in limestone.
(See 'Medals of Creation', p. 340.)

FOSSIL SHELLS IN CHALK.

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.

Lign. 4:—Fossil teeth of Fishes of the Shark family, in Chalk; from Lewes.
(See 'Medals of Creation.' p. 625.)

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])!

Lign. 5:—A few grains of Chalk-dust highly magnified, and shown to consist of shells, &c.

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.

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.

Lign. 6:—Minute fossil shells from Flint and Chalk, very highly magnified, and seen by transmitted light.

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.

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.

WHITBY SNAKE-STONES.

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.

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.

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.

Lign. 9:—View of Brighton Cliffs; looking eastward from Kemp Town.[I]

[I] [Note V.] Brighton Cliffs.

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.

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.

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.

[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.

FOSSIL ANIMALCULES.

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. .

XANTHIDIA IN FLINT.

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.

ROTALIA IN FLINT.

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.

Lign. 13:—Scales of Fishes in flint.

Plate II.

Longitudinal section of the Pebble.

Page 41.

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.

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.

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.

Lign. 14:—Choanites Konigi: from the Chalk.

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!

CORALS IN CHALK.

Lign. 15:—Branch of Coral on the Pebble.

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.

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:—

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.

Lign. 17:—Minute Corals from the Chalk;[R] highly magnified.

[R] [Note IX.] Minute corals from the Chalk.

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.

Lign. 18:—Animalcules from the Richmond earth: very highly magnified

[U] [Note X.] Richmond Infusorial earth.

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.

[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.